Probiotic and Muscadine Grape Extract Interventions Shift the Gut Microbiome and Improve Metabolic Parameters in Female C57BL/6 Mice

Obesity and Western-like diet consumption leads to gut microbiome dysbiosis, which is associated with the development of cardio-metabolic diseases and poor health outcomes. The objective of this study was to reduce Western diet-mediated gut microbial dysbiosis, metabolic dysfunction, and systemic inflammation through the administration of a novel combined intervention strategy (oral probiotic bacteria supplements and muscadine grape extract (MGE)). To do so, adult female C57BL/6 mice were fed a low-fat control or Western-style diet and sub-grouped into diet alone, probiotic intervention, antibiotic treatments, MGE supplementation, a combination of MGE and probiotics, or MGE and antibiotics for 13 weeks. Mouse body weight, visceral adipose tissue (VAT), liver, and mammary glands (MG) were weighed at the end of the study. Fecal 16S rRNA sequencing was performed to determine gut bacterial microbiome populations. Collagen, macrophage, and monocyte chemoattractant protein-1 (MCP-1) in the VAT and MG tissue were examined by immunohistochemistry. Adipocyte diameter was measured in VAT. Immunohistochemistry of intestinal segments was used to examine villi length, muscularis thickness, and goblet cell numbers. We show that dietary interventions in Western diet-fed mice modulated % body weight gain, visceral adiposity, MG weight, gut microbial populations, and inflammation. Intervention strategies in both diets effectively reduced VAT and MG fibrosis, VAT and MG macrophages, adipocyte diameter, and VAT and MG MCP-1. Interventions also improved intestinal health parameters. In conclusion, dietary intervention with MGE and probiotics modulates several microbial, inflammatory, and metabolic factors reducing poor health outcomes associated with Western diet intake.

Study design and methods for the pilot study of muscadine grape extract supplement to improve fatigue among older adult cancer survivors (FOCUS) trial

INTRODUCTION

Fatigue is a prevalent symptom among both cancer survivors and older adults. Negative consequences of fatigue include increased sedentary behavior, decreased physical activity and function, and lower quality of life. Few pharmacologic interventions improve fatigue. Our preclinical and clinical data show promising effects of a muscadine grape extract supplement (MGES) on oxidative stress, mitochondrial bioenergetics, the microbiome, and the symptom of fatigue. This pilot study seeks to translate these observations to cancer survivorship by testing the preliminary effect of MGE supplementation on older adult cancer survivors with self-reported fatigue.

MATERIALS AND METHODS

We designed a double-blinded placebo-controlled pilot study to evaluate preliminary efficacy of MGE supplementation versus placebo on fatigue among older adult cancer survivors (aged ≥65 years) who report baseline fatigue. Sixty-four participants will be enrolled and randomized 1:1 to twice daily MGES (four tablets twice daily) versus placebo for 12 weeks. The primary outcome is change in Patient-Reported Outcomes Measurement Information System (PROMIS) Fatigue score from baseline to 12 weeks. Secondary outcomes are change in self-reported physical function, physical fitness (6-min walk test), self-reported physical activity, global quality of life (QOL), and the Fried frailty index. Correlative biomarker assays will assess changes in 8-hydroxy-2 deoxyguanosine, peripheral blood mitochondrial function, inflammatory markers, and the gut microbiome.

DISCUSSION

This pilot study builds on preclinical and clinical observations to estimate effects of MGE supplementation on fatigue, physical function, QOL, and biologic correlates in older adult cancer survivors. Trial registration #: CT.govNCT04495751; IND 152908.

A Polyphenol-Rich Extract from Muscadine Grapes Prevents Hypertension-Induced Diastolic Dysfunction and Oxidative Stress

Muscadine grapes are abundant in dietary polyphenols, but their effect on hypertension-induced cardiac damage is limited. This study assessed whether a muscadine grape skin/seed extract supplement (MGES) prevents hypertension-induced cardiac damage and oxidative stress. Male Sprague Dawley rats were treated for four weeks with drinking water, angiotensin II (Ang II) to induce hypertension, MGES, or both Ang II and MGES. Cardiac function assessed by echocardiography showed that Ang II increased systolic blood pressure while MGES alone or in combination with Ang II had no effect. Ang II increased E/e′, an indicator of left ventricular filling pressure and diastolic dysfunction, by 41% compared to Control and co-treatment with MGES prevented the Ang II-mediated increase, suggesting that the extract attenuated hypertension-induced diastolic function. Ang II infusion increased urinary 8-hydroxy-2′-deoxyguanosine and cardiac 4-hydroxynonenal and malondialdehyde, which were prevented by the extract. The antioxidant enzymes catalase and superoxide dismutase 1 activity and mRNA were increased significantly in animals treated with MGES alone or in combination with Ang II, suggesting that the extract upregulates oxidative stress defense mechanisms in cardiac tissue. Thus, MGES may serve as a medical food to protect the heart from hypertension-induced diastolic dysfunction caused in part by excessive reactive oxygen species production.

Angiotensin-(1-7) reduces doxorubicin-induced aortic arch dysfunction in male and female juvenile Sprague Dawley rats through pleiotropic mechanisms

Doxorubicin (Dox), an effective chemotherapeutic, can cause cumulative dose-dependent cardiovascular toxicity, which may manifest as vascular dysfunction leading to long-term end-organ damage. Currently, there are no effective treatments to mitigate Dox-induced vascular damage in cancer patients, particularly pediatric patients. We showed that angiotensin-(1-7) [Ang-(1-7)], an endogenous peptide hormone, mitigated cardiac damage in Dox-treated juvenile rats. In this study assessing aortic stiffness, juvenile male and female rats were administered a clinically equivalent dose of Dox (21-24 mg/kg) over 6 weeks, in the presence and absence of Ang-(1-7) [24 µg/kg/h]. Aortic function was measured using echocardiography. Ang-(1-7) reduced the Dox-mediated increase in pulse wave velocity, a measure of arterial stiffness (males: p < 0.05; females: p < 0.001) as compared in control animals. Dox decreased aortic lumen diameter (p < 0.0001) and increased wall thickness (p < 0.01) in males, which was attenuated by Ang-(1-7). In male but not female aortic arches, Dox increased media hypertrophy (p < 0.05) and reduced elastin content (p < 0.001), which were prevented by Ang-(1-7). Conversely, Dox increased fibrosis (p < 0.0001) in juvenile female rats, which was reduced by Ang-(1-7). Adjunct Ang-(1-7) prevented the Dox-induced increase in total cell and nuclear pERK1/2 in the aortic intima and media of male rats and nuclear pSMAD2 in the intimal and medial regions of the aortic arches of both sexes. These results demonstrate that Ang-(1-7) attenuated Dox-induced aortic dysfunction in both sexes of juvenile rats, albeit through different mechanisms, suggesting that Ang-(1-7) may serve as an effective adjuvant to ameliorate cardiovascular and long-term end-organ damage in pediatric patients produced by anthracyclines.

Kristine M. Alpi, AHIP, FMLA, Medical Library Association President, 2021-2022

In this profile, Kristine M. Alpi, AHIP, FMLA, Medical Library Association (MLA) president, 2021-2022, is described as committed to public health, professional development, and the growth and evolution of MLA. She teaches and speaks on the shared health impact from interactions among animals, humans, and the environment, and she mentors graduate students and fellows in librarianship and informatics. Alpi earned her PhD in educational research and policy analysis in 2018 and directs the Oregon Health & Science University Library.

A Polyphenol-Rich Extract From Muscadine Grapes Inhibits Triple-Negative Breast Tumor Growth

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer that tends to affect young women and has a high propensity to metastasize. No targeted treatments are available for this type of breast cancer due to a lack of estrogen or progesterone receptors or overexpression of human epidermal growth factor receptor type 2 overexpression. Currently, patients have no therapeutic options once standard of care is complete, indicating a need for safe and effective therapies to slow or prevent the progression of TNBC to metastatic disease. Studies showed that isolated polyphenols or polyphenol-rich muscadine grape extracts polyphenols inhibit the proliferation of various cancer cells including breast cancer. A proprietary muscadine grape extract (MGE) was administered to nude mice with human MDA-MB-231 TNBC atumors for 4 weeks to determine the effect of the extract on tumor growth. MGE decreased tumor volume in association with a reduction in the proliferative markers Ki67 and cyclin D1. To determine the molecular mechanisms for the MGE-induced reduction in tumor growth, mouse 4T1, MDA-MB-231, or human BT-549 TNBC cells were treated with MGE, and various signaling pathways were investigated. MGE reduced c-Met, differentially abrogated ERK/MAPK and AKT signaling, and decreased a downstream targets of ERK/MAPK and AKT pathways, cyclin D1. Cyclin D1 reduction was associated with retinoblastoma activation and cell cycle arrest in MDA-MB-231 TNBC cells. MGE-regulated molecular signaling pathways were functionally associated with a dose-dependent reduction in cell proliferation. The pluripotency of MGE and high index of safety and tolerability suggest that the extract may serve as a therapeutic to reduce TNBC progression to metastatic disease.

Phase I Study of Muscadine Grape Extract for Patients With Advanced Cancer

OBJECTIVE

Preclinical studies with muscadine grape extract (MGE) show antitumor activity and decreased systemic inflammation. This phase I study (NCT02583269) assessed safety and tolerability of a proprietary MGE preparation in patients with advanced solid tumors.

METHODS

Patients with metastatic or unresectable cancers who were progressing on standard therapies were assigned to MGE in a standard 3+3 design. Five dose levels were tested (320 to 1600 mg total phenolics/d). Safety and maximum-tolerated dose were assessed after 4 weeks. Patients were evaluated for response at 8 weeks and continued on MGE if clinically stable. Secondary outcomes were response, survival, adherence, fatigue, and quality of life (QOL).

RESULTS

In total, 23 patients (lung, n=7; gastrointestinal, n=7; genitourinary, n=6; other, n=3) received MGE capsules by mouth twice daily. The cohort [median age 72 years, 48% Eastern Cooperative Oncology Group (ECOG) 2] was heavily pretreated. After 4 weeks on MGE, possibly attributable adverse events grade 2 or higher were fatigue (n=1), decreased lymphocyte count (n=1), and constipation (n=2), including 1 dose-limiting toxicity for grade 3 constipation. Maximum-tolerated dose was not reached. No partial responses were observed. Median time on therapy was 8 weeks, with 29% of patients treated beyond 16 weeks and a median overall survival of 7.2 months. QOL and fatigue levels were stable from baseline to 8 weeks. Higher MGE dose was correlated with improvement in self-reported physical well-being QOL at 8 weeks (r=0.6; P=0.04).

CONCLUSIONS

MGE is safe and well-tolerated in heavily pretreated and older cancer patients.  The potential anticancer properties and the effects of MGE on physical well-being and QOL metrics will be evaluated in future studies.

Abstract P053: Enhanced Exercise Capacity By Muscadine Grape Extract Treatment Is Only Evident In Older Hypertensive Female Rats And Is Independent Of Blood Pressure

Physical performance and systolic blood pressure (SBP) during aging in normotensive female Sprague-Dawley (SD) and hypertensive (mRen2)27 transgenic rats were assessed following long-term treatment with a Muscadine Grape Extract (MGE, Piedmont Research and Development Corp). MGE was administered at a dose of 0.2 mg/mL in the drinking water starting at 14 weeks (wks) of age with an endpoint at 70 wks of age (total time of treatment of 56 wks). At 20-, 40- and 70-wks of age, physical performance (exercise capacity in seconds and workload in grams - meters) was determined using a treadmill at a velocity of 17 cm/second with a 5% incline. SBP was determined by tail-cuff plethysmography in trained rats. There were no significant differences in physical performance between SD and (mRen2)27 female rats at any age despite the higher SBP in the (mRen2)27 rats at all ages. Long-term treatment with MGE had no significant effect on physical performance or SBP in SD rats at any age. In contrast, MGE treatment markedly increased exercise capacity (40 wks: 1615 ± 166 vs 4943 ± 442 seconds, p<0.01, n = 4-9; 70 wks: 2520 ± 374 vs 4117 ± 245 seconds, p<0.01, n = 4-8) and workload (40 wks: 4579 ± 490 vs 14730 ± 1353 grams - meters, p<0.01, n = 4-9; 70 wks: 8338 ± 1340 vs 13659 ± 933 grams - meters, p<0.01, n = 4-8) at the later ages in female (mRen2)27 rats, while there was no effect on SBP (20 wks: 167 ± 4 vs 173 ± 4 mm Hg, n = 4-6; 40 wks: 177 ± 8 vs 170 ± 7 mm Hg, n = 6-7; 70 wks:154 ± 6 vs 172 ± 6 mm Hg, n = 5) at any age. These data suggest that MGE treatment is effective in improving physical performance only in hypertensive female rats and may be independent of changes in blood pressure. The benefit of MGE in the older hypertensive female may reflect reductions in vascular stiffness and oxidative stress. Support: Chronic Disease Research Fund, Hypertension & Vascular Research Center

Abstract P045: Sex And Age Specific Circulating Aldosterone Changes In Transgenic Hypertensive (mRen2)27 Rats And Hannover Sprague Dawley (SD) Rats And Its Association With Blood Pressure And Cardiac Function

Aldosterone plays a significant role in hypertension and target organ damage. Aldosterone antagonists are used in the management of heart failure. However, neither the influence of age nor sex on aldosterone pathophysiology is well understood. We investigated the changes in circulating aldosterone with age and its association with cardiovascular function, using male and female hypertensive renin transgenic (mRen2)27 rats and SD rats at 20 and 50 weeks of age. Both male (22 ± 3 vs. 12 ± 2 ng/dL, n = 9 - 12, p < 0.05) and female (59 ± 10 vs. 23 ± 8 ng/dL, n = 6 - 10, p < 0.05) hypertensive rats had higher serum aldosterone compared with SD rats at 20 weeks of age. At 50 weeks of age, the difference persisted in the hypertensive female rats (63 ± 8 vs. SD: 33 ± 7 ng/dL, n = 6 - 7, p < 0.05), but not in the males. SD male rats have higher systolic blood pressure (SBP) as they age, and consequently develop cardiac diastolic dysfunction associated with higher aldosterone at 50 weeks compared to 20 weeks (28 ± 3 vs. 12 ± 2 ng/dL, n = 7 - 9, p < 0.05). This aging effect on aldosterone was not significant in the other groups. We showed previously that SD males treated with polyphenol rich muscadine grape extract (MGE) have lower aldosterone, less aortic stiffness and better cardiac diastolic function (E/e’) than controls at the older age; the MGE effect was not seen in (mRen2)27 males. Sex differences in aldosterone were not significant in the SD rats at either time point. However, (mRen2)27 female rats had higher aldosterone than (mRen2)27 males at both 20 weeks (59 ± 10 vs. 22 ± 3 ng/dL, n = 10 - 12, p < 0.05) and 50 weeks (63 ± 8 vs. 31 ± 7 ng/dL, n = 6 - 7, p < 0.05), despite the lack of significant differences in SBP. (mRen2)27 female rats preserve cardiac function better than males throughout their life span, while males develop indices of heart failure. Our data suggest that lower aldosterone levels in hypertensive males compared with females do not protect against the higher lifetime burden of elevated SBP and also may reflect different mechanisms controlling circulating aldosterone between sexes. In addition, data suggest a potential therapeutic effect of MGE in the management of age-associated moderate hypertension.

Angiotensin-(1–7) reduces doxorubicin-induced cardiac dysfunction in male and female Sprague-Dawley rats through antioxidant mechanisms

Doxorubicin (Dox) is an effective chemotherapeutic for a variety of pediatric malignancies. Unfortunately, Dox administration often results in a cumulative dose-dependent cardiotoxicity that manifests with marked oxidative stress, leading to heart failure. Adjunct therapies are needed to mitigate Dox cardiotoxicity and enhance quality of life in pediatric patients with cancer. Angiotensin-(1–7) [Ang-(1–7)] is an endogenous hormone with cardioprotective properties. This study investigated whether adjunct Ang-(1–7) attenuates cardiotoxicity resulting from exposure to Dox in male and female juvenile rats. Dox significantly reduced body mass, and the addition of Ang-(1–7) had no effect. However, adjunct Ang-(1–7) prevented Dox-mediated diastolic dysfunction, including markers of decreased passive filling as measured by reduced early diastole mitral valve flow velocity peak ( E) ( P < 0.05) and early diastole mitral valve annulus peak velocity ( e′; P < 0.001) and increased E/e′ ( P < 0.001), an echocardiographic measure of diastolic dysfunction. Since Dox treatment increases reactive oxygen species (ROS), the effect of Ang-(1–7) on oxidative by-products and enzymes that generate or reduce ROS was investigated. In hearts of male and female juvenile rats, Dox increased NADPH oxidase 4 ( P < 0.05), a major cardiovascular NADPH oxidase isozyme that generates ROS, as well as 4-hydroxynonenal ( P < 0.001) and malondialdehyde ( P < 0.001), markers of lipid peroxidation; Ang-(1–7) prevented these effects of Dox. Cotreatment with Dox and Ang-(1–7) increased the antioxidant enzymes SOD1 (male: P < 0.05; female: P < 0.01) and catalase ( P < 0.05), which likely contributed to reduced ROS. These results demonstrate that Ang-(1–7) prevents diastolic dysfunction in association with a reduction in ROS, suggesting that the heptapeptide hormone may serve as an effective adjuvant to improve Dox-induced cardiotoxicity.

NEW & NOTEWORTHY Ang-(1–7) is a clinically safe peptide hormone with cardioprotective and antineoplastic properties that could be used as an adjuvant therapy to improve cancer treatment and mitigate the long-term cardiotoxicity associated with doxorubicin in pediatric patients with cancer.

Library resource sharing and the Medical Library Center of New York

The creation of the Medical Library Center of New York (MLCNY) was a significant contribution to the history of health sciences librarianship as a model for cooperative, democratic, and practical solutions to the issues of storage and resource sharing. The MLCNY's founding director, Erich Meyerhoff, was a key figure in the successful start-up and ongoing operations of the center, which operated from 1960-2003 and served the greater New York area and beyond. This essay traces the evolution of the center including the creation of the Union Catalog of Medical Periodicals and the demise of the center occasioned by changes in scholarly publishing, technology, and constituent needs.

Abstract P2007: Muscadine Grape Extract Prevents Cardiac Cell Cytotoxicity Due to Oxidative Stress by Enhancing Mitochondrial Function

Mitochondrial health is critical for the physiological function of tissues and responses to stress. During oxidative stress, failure to maintain mitochondrial respiration can ultimately lead to cell death and thus cardiac dysfunction. Agents that preserve mitochondrial integrity and maintain or increase mitochondrial respiratory capacity may prevent cardiac tissue damage due to oxidative stress. Muscadine grapes are rich in polyphenols, which are natural antioxidants, and are known to reduce cardiac damage. We treated cardiac cells with a proprietary muscadine grape extract (MGE), to prevent cardiac myoblast death due to reactive oxygen species (ROS) in the presence of the redox cycling agent 2,3 dimethoxynaphthoquinone (DMNQ), which generates both superoxide and hydrogen peroxide intracellularly, thus mimicking pathologies of elevated ROS. DMNQ increased cardiac cell cytotoxicity, as measured by LDH release, which was prevented by doses of MGE equivalent to 60 μg/mL of total phenolics (1.3 ± 0.023 DMNQ vs. 0.90 ± 0.030, n=3, *p<0.01). Moreover, cell respirometry measurements indicated that, while DMNQ reduced the oxygen consumption rate (OCR) by 50% (*p<0.05, n=3), treatment with MGE prevented this reduction, suggesting that the protective effect may be mediated by preservation of mitochondrial function. Furthermore, MGE treatment prevented the decrease in ATP-linked respiration (18.8 ±. 2.6 DMNQ vs. 34.0±.4.7 DMNQ + MGE, n=3, *p<0.01) and maximal respiratory capacity (31.6 ± 8.2 DMNQ vs. 48.91 ± 6.54 DMNQ + MGE, n=3, *p<0.01) observed with DMNQ treatment. Furthermore, the basal extracellular acidification rate (ECAR) was increased 2-fold with MGE pretreatment when compared to DMNQ alone (13.6 ± 2.3 DMNQ + MGE vs. 6.8 ±.0.88 DMNQ, n=3, *p<0.01), suggesting that MGE treatment may also increase glycolysis as a response to stress. These data suggest that MGE enhances mitochondrial function and cellular bioenergetics in cardiomyoblast cells during stress and thus may be used as a strategy to prevent tissue damage from oxidative stress observed in acute and chronic cardiac pathologies.

Abstract P3006: Angiotensin-(1-7) Prevents Doxorubicin-Induced Aortic Dysfunction Through Anti-Fibrotic Mechanisms in Juvenile Male and Female Sprague Dawley Rats

Doxorubicin (Dox) is an effective, anthracycline chemotherapeutic administered for a variety of malignancies, but clinical use of the drug is limited by a cumulative, dose-dependent cardiotoxicity. Thus, adjuvant therapies are needed to mitigate Dox-induced cardiovascular damage in cancer patients, especially in pediatric patients with decades of life ahead. Our group showed that angiotensin-(1-7) [Ang-(1-7)], an endogenous peptide hormone with anti-cancer properties, improved vascular dysfunction in coronary vessels and cremaster muscle microvessels in Ang II-infused rats. In this study, juvenile male and female Sprague Dawley rats (n = 8-10) were administered a clinically equivalent dose of Dox (21-24 mg/kg) over 6 weeks, in the presence or absence of Ang-(1-7) [24 μg/kg/h]. Aortic function was measured using echocardiography. In both sexes, Ang-(1-7) blocked the Dox-mediated increase in pulse wave velocity (PWV), a measure of arterial stiffness (75% in males and 179% in females, p<0.05 and p<0.001). Dox decreased aortic lumen diameter (by 18%, p<0.01) and increased wall thickness at systole (p<0.01) in males, which was attenuated by Ang-(1-7). In male but not female aortas, Dox increased media hypertrophy by 16% (p<0.01) and reduced elastin content by 17% compared to control rats (p<0.001), changes prevented by Ang-(1-7). Conversely, collagen deposition was increased 2.5-fold in the aortic arches of female rats treated with Dox (p<0.001), which was blocked by Ang-(1-7). Dox increased nuclear ERK1/2 by 2-fold in the aortic media of male rats (p<0.01) and Ang-(1-7) significantly attenuated nuclear ERK1/2 localization. In contrast, neither Dox nor Ang-(1-7) changed total or nuclear ERK1/2 in the aortic arches of female rats. Dox increased nuclear pSMAD2 4-fold in males (p<0.05) and 3-fold in females (p<0.05); prophylactic treatment with Ang-(1-7) reduced the Dox-induced increases in nuclear pSMAD2 while the heptapeptide hormone had no effect alone. These results demonstrate that Ang-(1-7) prevented Dox-induced aortic dysfunction in both sexes, albeit through different mechanisms, suggesting that treatment with Ang-(1-7) may serve as an effective adjuvant to improve Dox-induced vascular dysfunction in pediatric patients.

Abstract P3052: A Muscadine Grape Extract Improves Hypertension-Induced Aortic Damage in Conjunction With a Reduction in Fibrosis, Oxidative Stress, and Inflammation

Hypertension-induced arterial stiffness contributes to both reduced vascular and cardiac function. While the pathophysiology of aortic stiffness is not completely understood, significant vascular remodeling occurs in response to stimuli such as vascular stress and Ang II. The goal of this study was to determine whether a polyphenol-enriched muscadine grape skin and seed extract (MGE) improves Ang II-induced aortic remodeling. Sprague-Dawley rats (male, 8 weeks old) received normal drinking water (Control), 0.2 mg total phenolics/mL in their drinking water (MGE), 24 μg/kg/h of Ang II via osmotic minipump (Ang II), or both Ang II and MGE (Ang II/MGE, pre-treated with MGE for 1 week prior to Ang II treatment). MGE had no effect on systolic blood pressure, measured by tail cuff plethysmography, in normotensive or Ang II-treated rats. Aortic stiffness, determined by echocardiographic pulse wave velocity, was increased 2.5-fold in Ang II-treated animals but was significantly improved by co-administration of MGE. MGE prevented the Ang II-induced increase in aortic media thickness (Control: 95.8 ± 2.1 μm, Ang II: 135.1 ± 3.7 μm, and Ang II/MGE: 118.2 ± 2.9 μm) and lumen diameter (Control: 2.7 ± 0.2, Ang II: 2.1 ± 0.1 mm, and Ang II/MGE: 2.6 ± 0.1 mm). Nuclear phosphorylated ERK (pERK) in aortic medial cells was increased by 131% in Ang II-treated rats compared to Controls (p < 0.05); MGE co-administration prevented this by 83% (p < 0.001). Ang II-induced aortic fibrosis, measured by total collagen and collagen III, was significantly attenuated in hypertensive animals treated with MGE, in association with reduced pSMAD2 and CTGF. 4-HNE, a marker of lipid peroxidation, and subunits of NADPH oxidases--Nox1, Nox2, p-p47phox--were significantly upregulated by Ang II and normalized with MGE. The inflammatory markers IL-6 and NF-κB were also increased in Ang II-treated aortas (8.9- and 12.7-fold, respectively) and attenuated by MGE. This study is the first to demonstrate that Ang II-induced vascular remodeling is prevented by co-administration of MGE. MGE reduced aortic stiffness, in association with a decrease in fibrotic, oxidative stress, and inflammatory signaling, suggesting that MGE supplementation may improve vascular function in hypertensive patients.

Abstract P155: Chronic Muscadine Grape Extract Intake Improves Diastolic Function Associated With Lower Circulating Aldosterone in Hannover Sprague Dawley Male Rats

Muscadine grapes are rich sources of polyphenols, which are natural anti-oxidants linked to cardiovascular health. Circulating aldosterone may contribute to cardiac diastolic dysfunction via pro-oxidant and pro-fibrotic effects. We investigated the effect of chronic treatment with a muscadine grape extract (MGE) on circulating aldosterone and cardiac function in Hannover Sprague Dawley (SD) rats, since we previously showed that male rats develop diastolic dysfunction by 60 weeks of age. MGE (Piedmont Research & Development Corp.) was administered in the drinking water (0.2 mg polyphenolics /mL) starting at 15 weeks of age. Control animals were given regular water. Animals were assessed after 15 and 30 weeks of treatment. At 30 weeks of age, male SD rats have higher systolic blood pressure (SBP, measured by tail-cuff plethysmography: 139 ± 5 vs. 124 ± 2, n = 7-8, p < 0.05), higher E/e’ (measured by Vevo LAZR ultrasound: 12.9 ± 0.7 vs. 10.9 ± 0.2, n = 5-8, p < 0.05), and lower ejection fraction (77 ± 2 vs. 82 ± 1, n = 5-8, p < 0.05) than females at 30 weeks of age. SBP was lower in MGE treated males (126 ± 2 vs. 139 ± 5, n=7-8, p < 0.05) but not in females at 30 weeks of age. At 45 weeks of age, MGE treated male rats had improved (lower) E/e’ ratio than control male rats (E/e’: 10.7 ± 0.6 vs. 13.4 ± 0.4, n = 7, p < 0.05). This effect was accompanied by lower serum aldosterone (15 ± 3 vs. 28 ± 3 ng/dL, n = 7, p < 0.05) at 45 weeks of age. The MGE effects were independent of differences in SBP, ejection fraction, cardiac output or LV mass at this time point in male rats. For the female SD rats, there were no differences in SBP, cardiac systolic or diastolic function comparing values at 30 and 45 weeks of age, and no effect of MGE treatment at either time point. Serum aldosterone was not lower in the female rats at 45 weeks of age relative to control females. Our data demonstrate sex differences in cardiac function in response to chronic MGE consumption in aging rats. The MGE-induced improvement in diastolic cardiac function in males is consistent with lower circulating aldosterone. Our results suggest a protective role for MGE in age-related cardiac dysfunction in males.

Abstract 129: The Microbiome Product Urolithin a Abrogates the Tgf-β Egfr Pai-1 Pathway by Inhibiting Egfr Activation and Expression

Introduction: Ellagitanins are highly abundant in various foods including fruits, nuts and wines, and particularly high in commercial muscadine grape-derived supplements. The microbiome metabolizes ellagitanins to urolithins. Urolithin A (UA), the final product of the microbiome processing pathway may contribute to the cardioprotective effects of ellagitanins; however, the cellular signaling mechanisms of UA are unclear. Since the TGFβ-PAI-1 pathway contributes to fibrosis, cellular senescence and progressive kidney injury, we evaluated the effects of UA on TGFβ-induced stimulation of PAI-1 in rat renal proximal tubule cells (rPTCs - NRK52E). We hypothesize that UA may be an endogenous anti-fibrotic compound that attenuates the TGFβ-PAI-1 response.

Results: TGFβ (5 ng/ml) treatment markedly increased PAI-1 levels 10-fold [43.9 ± 0.7 vs 3.5 ± 0.3 ng/ml; P<0.001, n=3] in the rPTCs at 24 hrs. The TGFβ receptor (TGFβR) kinase (ALK5) inhibitor SB525334 or UA abolished the increase in PAI-1 to TGFβ [SB: 1.3 ± 0.3; UA: 2.0 ± 0.4 ng/ml; P<0.001, n=3]; UA exhibits an IC50 of 3.1 μM to abrogate the TGFβ-PAI-1 response. Since the TGFβ pathway may transactivate the EGFR, treatment with the EGFR kinase inhibitors AG1478 (AG, 1 μM) and Lapatinib (LAP, 1 μM) also abrogated the PAI-1 response to TGFβ [AG: 3.3 ± 0.4; LAP: 6.2 ± 1.4 ng/ml; P<0.001, n=3]. Addition of EGF alone increased PAI-1 to a similar extent as TGFβ [46.6 ± 2.7 ng/ml; P<0.001, n=3], and treatment with UA or AG abolished the EGF-PAI-1 response [2.4 ± 0.1 and 1.3 ± 0.1 ng/ml, respectively; P<0.001, n=3]. Given the dependence on EGFR signaling for PAI-1, we determined whether UA directly attenuates EGFR stimulation. Indeed, UA treatment inhibited peak EGFR phosphorylation to EGF at 5 mins [10 μM: 67 ± 4%; 50 μM: 71 ± 5%; P<0.05, n=3], and reduced total EGFR expression at 24 hrs [10 μM: 27 ± 11%; 50 μM: 66 ± 7%; P<0.05, n=6]. UA was devoid of cytotoxic effects (LDH release).

Conclusion: The present study is the first to establish that UA abrogates the TGFβ-EGFR-PAI-1 pathway via the inhibition of EGFR stimulation and expression. Moreover, the potency of UA to attenuate PAI-1 is comparable to its physiological levels. The microbiome product UA may convey anti-fibrotic actions within the kidney by targeting the EGFR system.

Abstract 1860: Muscadine grape extract prevents proliferation of trastuzumab-sensitive and -resistant HER2 positive breast cancer cells and has synergistic effects when combined with trastuzumab

Human epidermal growth factor receptor 2 (HER2) positive breast cancer, characterized by overexpression of the HER2 protein, is an aggressive type of breast cancer comprising ~20% of diagnosed cases. Although targeted HER2 drugs, such as trastuzumab (TRZ), have reduced mortality by about one third, many patients still experience primary or acquired resistance. Grape seed/skin extracts are popular dietary supplements due to their potent antioxidant and anti-inflammatory properties. However, extracts from muscadine grapes are not extensively studied, and information regarding their therapeutic effects on cancer is limited. The objective of this study was to determine whether a muscadine grape skin and seed extract (MGE) inhibits the proliferation of TRZ-sensitive and -resistant HER2 positive breast cancer cells, and determine if combination treatment with MGE and TRZ has synergistic effects. Treatment with increasing concentrations of MGE for 48h significantly inhibited proliferation of TRZ-sensitive SKBR3 and -resistant HCC1954 human HER2 overexpressing breast cancer cells in a time and dose-dependent manner. HER2 heterodimerization and phosphorylation results in activation of the protein kinase B (AKT) pathway, which regulates breast cancer proliferation and cell survival. Treatment with 20 μg/mL MGE for 24h reduced HER2 protein expression by 52% (p≤0.01) in SKBR3 and 60% (p≤0.01) in HCC1954 cells. AKT activation was also reduced by 63% (p≤0.001) and 65% (p≤0.0001) in SKBR3 and HCC1954 cell lines, respectively. Active AKT stabilizes s-phase kinase-associated protein 2 (SKP2), ultimately leading to increased ubiquitination and degradation of cell-cycle inhibitor cyclin-dependent kinase inhibitor 1B (p27) and its transcription factor forkhead box protein 1 (FOXO1). Treatment with 20 μg/mL MGE for 24h increased total FOXO1 and p27 levels by 4-fold (p≤0.01) and 2.5-fold (p≤0.05), respectively, in SKBR3 cells. In addition, FOXO1 was increased 5-fold (p≤0.0001) and p27 4-fold (p≤0.05) in HCC1954 cells. Furthermore, SKP2 protein expression was reduced by 66% (p≤0.01) in SKBR3 and 73% (p≤0.01) in HCC1954 cells. MGE, in combination with TRZ, was synergistic at five different dose combinations (determined using Chou and Talalay method of synergy), and significantly inhibited proliferation to a greater extent than either agent alone in TRZ-sensitive SKBR3 cells. In summary, treatment with MGE reduced proliferation, inhibited components of the AKT pro-proliferation/survival pathway, and had synergistic effects when combined with TRZ in HER2 positive breast cancer cells. Thus, MGE may serve as an effective therapeutic either administered singly or in combination with targeted therapies for the treatment of HER2 positive breast cancer.

Citation Format: Jessica Mackert, Patricia E. Gallagher, E. Ann Tallant. Muscadine grape extract prevents proliferation of trastuzumab-sensitive and -resistant HER2 positive breast cancer cells and has synergistic effects when combined with trastuzumab [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1860.

Abstract 2885: Angiotensin-(1-7) prevents doxorubicin-induced cardiotoxicity by reducing oxidative stress and fibrosis

Doxorubicin (Dox) is an effective chemotherapeutic agent for various malignancies including childhood leukemias and lymphomas. Unfortunately, Dox administration often results in a cumulative dose-dependent cardiotoxicity that manifests as cardiomyopathy with marked oxidative stress and fibrosis leading to a long-term reduction in cardiovascular function and heart failure. Adjunct therapies to mitigate Dox-induced cardiotoxicity and enhance long-term quality-of-life in cancer patients are needed, particularly for pediatric patients. Angiotensin-(1-7) [Ang-(1-7)] is an endogenous heptapeptide hormone of the renin-angiotensin system with cardioprotective properties. We investigated whether adjunct Ang-(1-7) attenuates cardiotoxicity resulting from acute (6 week) exposure to Dox (21-24 mg/kg) in male and female juvenile rats (n = 7-10). Dox treatment reduced body/heart mass in male and female rats and co-administration of Ang-(1-7) had no effect on these morphological changes. However, co-administration of the heptapeptide hormone prevented Dox-mediated diastolic dysfunction, including decreased passive filling (E; 16%, p&lt;0.05) and mitral annulus tissue movement (e'; 45% in males and 31% in females, p&lt;0.001) and the subsequent increased filling pressure (E/e'; 47% in males and 43% in females, p&lt;0.001). In both male and female rat hearts, Dox administration increased NADPH oxidase 4 (Nox4; 2-fold in males and females, p&lt;0.05), the major Nox isozyme that generates ROS in the heart, as well as 4-hydroxynonenal (4-HNE; 7.5-fold in males and 3.5-fold in females, p&lt;0.001) and malondialdehyde (MDA; 20-fold in males and 15-fold in females, p&lt;0.001), markers of lipid peroxidation. Co-administration of Ang-(1-7) prevented these effects of Dox while Ang-(1-7) alone had no effect. Treatment of rats with Dox and Ang-(1-7) also increased cardiac superoxide dismutase 1 (SOD1; 4-fold in males and 5-fold in females, p&lt;0.05 and p&lt;0.01 respectively) and catalase (10-fold in males and 4-fold in females, p&lt;0.05), further contributing to reduced oxidative stress. Oxidative stress is associated with an increase in cardiac fibrosis, a maladaptive change that exacerbates cardiac dysfunction. Treatment of male and female rats with Dox increased collagen deposition in the heart which was associated with an increase in the fibrogenic cytokine TGF-β1 and TGF-β1-activated phospho-SMAD2; co-administration of Ang-(1-7) mitigated the Dox-induced increase in fibrosis while the heptapeptide hormone alone had no effect. The anti-oxidant and anti-fibrotic effects of Ang-(1-7) may account for the improvement in diastolic function by the heptapeptide hormone, suggesting that treatment with Ang-(1-7) may serve as an effective adjuvant to improve Dox-induced cardiac dysfunction.

Citation Format: Patricia E. Gallagher, Omeed Rahimi, Brian Westwood, Jay Kirby, Jasmina Varagic, Elisabeth Ann Tallant. Angiotensin-(1-7) prevents doxorubicin-induced cardiotoxicity by reducing oxidative stress and fibrosis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2885.

Abstract P193: Anti-fibrotic and Anti-oxidant Actions of a Muscadine Grape Extract Supplement on Hypertension-induced Cardiac Damage

Approximately 75 million U.S. adults suffer from hypertension, an independent risk factor for pathological cardiac hypertrophy. The current study examines the effects of a muscadine grape extract formulation (MGE; Piedmont Research & Development Corp.) with anti-oxidant, anti-inflammatory, and anti-proliferative properties on hypertension-induced cardiac damage in Sprague-Dawley rats receiving a 4-week Ang II infusion (24 μg/kg/h). We previously showed that MGE in the drinking water had no effect on blood pressure or systolic function in normotensive or hypertensive rats; however, MGE ameliorated the Ang II-induced decrease in diastolic function and increase in cardiomyocyte cross-sectional area. In the current study, MGE supplementation of Ang II-treated rats decreased interstitial cardiac fibrosis, reducing collagen III staining in the myocardium (0.9 ± 0.2% control, 6.8 ± 1.0% Ang II, and 2.8 ± 0.4% Ang II/MGE; p<0.01). MGE alone had no effect on any parameters assessed. The positive correlation between collagen and diastolic function with Ang II compared to control (p<0.01) was significantly abrogated by co-administration of MGE. TGFβ is a critical cytokine that stimulates cardiac fibrosis. The Ang II-mediated increase in cardiac TGFβ mRNA was attenuated by MGE (relative gene expression: 1.0 ± 0.1 control, 2.0 ± 0.4 Ang II, 1.1 ± 0.2 Ang II/MGE; p<0.05) as was downstream pSmad2 protein in cardiomyocytes (% nuclei: 26.1 ± 6 control, 53.8 ± 9.6 Ang II, 27.6 ± 5.5 Ang II/MGE; p<0.05) and cardiac fibroblasts (2.3 ± 1.1 control, 11.7 ± 4.9 Ang II, 2.2 ± 0.5 Ang II/MGE; p<0.05). NADPH oxidase is a primary contributor to cardiac oxidative stress and excess ROS production can lead to activation of pro-fibrotic pathways. MGE significantly reduced the Ang II-induced increase in p22phox mRNA (relative gene expression: 1.0 ± 0.1 control, 1.9 ± 0.1 Ang II, 1.0 ± 0.1 Ang II/MGE; p<0.0001) and protein (relative density: 1.0 ± 0.2 control, 5.4 ± 1.6 Ang II, 2.9 ± 1.0 Ang II/MGE; p<0.05), a subunit required for NADPH oxidase activity. These results indicate that MGE ameliorates cardiac fibrosis by targeting NADPH oxidase and the TGFβ pro-fibrotic pathway, suggesting that MGE supplementation may be an effective, natural therapeutic for hypertension-induced cardiac damage.

Abstract P190: Long-term Intake of Muscadine Grape Extract Markedly Improves Exercise Capacity in Older Female (mRen2)27 Hypertensive Rats

Muscadine grapes ( Vitis rotundifolia ) contain significant levels of polyphenols and their antioxidant capacity may have cardiovascular benefit. We determined the cardiovascular effects of a water soluble muscadine grape extract (MGE) from Piedmont Research & Development Corporation (PRDC, Winston-Salem, NC) that we confirmed has a high content of epicatechin, gallic acid, ellagic acid and procyanidin B2. We hypothesize that this soluble MGE with a potentially high phenolic bioavailability exhibits cardioprotective actions. The effect of long-term MGE intake on blood pressure, cardiac function and exercise tolerance was established in female and male hemizygous (mRen2)27 [mRen2] transgenic rats, an Ang II-AT 1 R-dependent model of hypertension. The mRen2 were administered MGE (8 mg of total phenolics/mL) in the drinking water for 26 weeks (7 female; 7 male); control rats (9 female; 11 male) were given water only. At 40 weeks of age, exercise tolerance was assessed by treadmill (10.2 m x min -1 , 5% inclination). The MGE-treated female mRen2 exhibited a >300% improvement in workload ( W: g X m ) as compared to the untreated group [14551 ± 1313 vs. 4498 ± 481; p<0.01]. MGE intake also extended the time to fatigue (TTF) by 300% in females (4943 ± 443 vs.1615 ± 166 sec; p<0.01). In contrast, chronic intake of MGE had no effect on either exercise workload or TTF in the male mRen2. MGE intake did not alter systolic blood pressure in females (162 ± 3 vs. 166 ± 6 mm Hg, p>0.05) and males (165 ± 5 vs. 160 ± 3 mm Hg) nor alter body weight in either group [females: 334 ± 7 g vs. 339 ± 8 g; males: 613 ± 12 g vs. 590 ± 6 g). Echocardiographic analyses revealed that although the female mRen2 exhibited a higher ejection fraction [73.4±5.1 vs. 42.3±4.5%, n=4-5, p<0.05] and a higher fractional shortening [44.2±4.2 vs. 22.1±2.7%, n=4-5, p<0.05] as compared to males, MGE treatment did not improve these indices in either group. We conclude that the marked improvement in exercise capacity in older adult hypertensive females by chronic MGE intake is not accompanied by augmented cardiac performance, perhaps reflecting the lack of an effect on blood pressure. Thus, it is possible that MGE may directly impact the skeletal muscle to improve exercise in the hypertensive mRen2 females, but not the males.

Abstract 1227: Angiotensin-(1-7) reduces triple negative breast cancer brain metastatic growth in association with decreased c-Met signaling

Patients with triple negative breast cancer often develop metastatic brain disease and have limited treatment options due to the lack of targeted therapeutics that efficiently cross the blood brain barrier. In the current study, we investigated the effect of angiotensin-(1-7) [Ang-(1-7)], a heptapeptide hormone with anti-proliferative and anti-metastatic activities, on the growth of murine brain tumors using brain trophic BR.5-4T1 cells in a model of metastatic triple negative breast tumor growth. BR.5-4T1 cells (1.25 x 104) were injected into the internal carotid artery of female BALB/c mice; after two days, mice were implanted with osmotic mini-pumps to deliver 24 µg/kg/h Ang-(1-7) and all mice were sacrificed after 20 days of treatment. Ang-(1-7) treatment significantly reduced metastatic tumor number in the brain; an average of 20 metastatic lesions per mouse was observed in the brains of an untreated control cohort while an average of 3 metastatic tumors per mouse was observed in the Ang-(1-7)-treated cohort. Tumor size was also reduced 17-fold by treatment with Ang-(1-7). Ki67, a marker of proliferation, was decreased from 29.1±6.7% to 6.4±2.2% in tumors from mice treated with Ang-(1-7), indicating that the heptapeptide hormone decreased metastatic tumor burden in the brain. Aberrant activation of the c-Met receptor tyrosine kinase signaling pathway facilitates tumor cell invasion and metastasis. Treatment with Ang-(1-7) significantly reduced the percentage of metastatic tumor cells exhibiting phospho-c-Met immunoreactivity, from 20.8±3.4% in tumors from untreated mice to 6.7±2.6% in mice treated with Ang-(1-7). Protein phosphatase 1b (PTB1b), which dephosphorylates and negatively regulates phospho-c-Met, was increased in the tumor cells of mice treated with Ang-(1-7) compared to tumor cells from untreated animals, from 4.1±1.4% in sections of tumors from control mice compared to 8.8±0.9% in sections of tumors from mice treated with Ang-(1-7). These results suggest that Ang-(1-7) increases PTP1b to antagonize c-Met signaling and decrease triple negative breast cancer brain metastasis. In support of a role for c-Met signaling in the regulation of metastatic brain disease in breast cancer patients, analysis of publicly available breast cancer cohort databases demonstrated a significant correlation between low c-Met/high PTP1b expression and improved survival outcome, including an increase in brain metastasis-free survival and distant-metastasis free survival. This is the first report to demonstrate that Ang-(1-7) reduces metastatic triple negative breast cancer localized to the brain in association with increased protein phosphatase PTP1b and decreased phospho-c-Met, suggesting that the heptapeptide hormone may serve as a novel targeted therapy to reduce metastatic brain tumor burden in triple negative breast cancer patients.

Citation Format: E. Ann Tallant, Guorui Deng, Wenhong Chen, Linda J. Metheny-Barlow, Patricia E. Gallagher. Angiotensin-(1-7) reduces triple negative breast cancer brain metastatic growth in association with decreased c-Met signaling [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1227. doi:10.1158/1538-7445.AM2017-1227

Abstract P166: The Effect of a Muscadine Grape Extract on Angiotensin II-Induced Hypertension and Cardiac Damage

Muscadine grapes, indigenous to the southeastern United States, are a dietary source of polyphenols, such as ellagic acid, quercetin, and resveratrol, which have both anti-inflammatory and antioxidant properties. Preclinical studies show that ground muscadine grape skins and seeds have anti-cancer effects, suggesting that supplementation with a muscadine grape extract (MGE) may serve as a chemotherapeutic or chemopreventive agent. As cancer patients often present with hypertension, diabetes, and other vascular pathologies, it is imperative to determine the effect of a muscadine grape supplement on these underlying comorbidities. The goal of this study was to determine whether MGE administered in the drinking water will exacerbate or improve hypertension and cardiac damage. Sprague-Dawley rats receiving a 4-week infusion of Ang II via subcutaneous osmotic mini-pump (24 μg/kg/h) had a significant increase in systolic blood pressure (123.1 ± 2.3 mm Hg in control vs. 213.1 ± 6.8 mm Hg in Ang II-treated; n=8; p < 0.0001). MGE supplementation had no effect on blood pressure or gross cardiac hypertrophy in either normotensive or hypertensive rats. Additionally, MGE did not alter stroke volume or cardiac output, measured by VEVO ultrasound. However, MGE ameliorated the Ang-II induced decrease in diastolic function, as measured by the E/E’ ratio (19.9 ± 0.8 in control, 28.1 ± 1.1 in Ang II-treated rats, 22.3 ± 2.0 in Ang II/MGE-treated rats; p < 0.05). Co-treatment with MGE also significantly reduced the Ang II-mediated increase in cardiomyocyte cross-sectional area (340.5 ± 12.0 μm 2 in control, 423.2 ± 17.1 μm 2 in Ang II-treated rats, and 342.6 ± 13.2 μm 2 in Ang II/MGE-treated rats, p < 0.01). MGE supplementation of Ang II-treated rats decreased interstitial cardiac fibrosis, measured by Picrosirius red staining (1.0 ± 0.1% in control, 2.0 ± 0.2% in Ang II-treated rats and 1.4 ± 0.1% in Ang II/MGE-treated rats, p < 0.05). These results demonstrate that treatment with MGE does not exacerbate hypertension or hypertension-induced cardiac damage but ameliorates cardiac hypertrophy, suggesting that MGE supplementation has an acceptable safety profile for use as an anti-cancer agent in hypertensive patients and may be used to treat cardiac hypertrophy and damage.

Abstract 023: Angiotensin-(1-7) Reduces Doxorubicin-Induced Cardiac Fibrosis

Doxorubicin (Dox) is a commonly used and effective chemotherapeutic agent for childhood leukemias and sarcomas. However, Dox administration often results in cumulative dose-dependent cardiotoxicity that manifests as cardiomyopathy with marked fibrosis that leads to reduced cardiovascular function and heart failure. Consequently, there is a need for adjunct therapies to reduce Dox-induced cardiotoxicity and enhance long-term quality-of-life in cancer patients, especially in pediatric patients. Angiotensin-(1-7) [Ang-(1-7)] is an endogenous peptide hormone of the renin-angiotensin system with cardioprotective properties; studies by us and others showed that Ang-(1-7) reduces cardiac fibrosis and improves cardiac function in various animal models. In this study, we investigated whether adjunct Ang-(1-7) attenuates cardiotoxicity resulting from an acute (6 week) exposure of juvenile Sprague-Dawley rats (male, n = 8-10) to Dox (22 mg/kg). Dox treatment reduced body mass, cardiac weight and cardiomyocyte size, while Ang-(1-7) co-administration had no effect on these changes. However, co-administration of Ang-(1-7) prevented Dox-mediated increases in cardiac fibrosis (interstitial fibrosis: 1.4 ± 0.1% to 2.5 ± 0.3%; perivascular fibrosis: 15.8 ± 1.4% to 23.2 ± 1.6%; p < 0.01) and coronary vessel hypertrophy (media-to-lumen ratio: 2.4 ± 0.2 to 3.3 ± 0.3; p < 0.05). Administration of Dox significantly increased E/E’ by 47%, a marker of diastolic dysfunction, and pulse wave velocity by 74%, as a measure of arterial stiffness, quantified using a Vevo 2100 small animal ultrasound system; co-administration of Ang-(1-7) prevented the Dox-induced increases in diastolic dysfunction and arterial stiffness. In contrast, Ang-(1-7) had no effect on the Dox-mediated reductions in ventricular diameter, parasternal wall thickness, stroke volume and cardiac output. The anti-fibrotic and anti-hypertrophic effects of Ang-(1-7) may account for the improvement in diastolic and arterial function. Collectively, these results suggest that adjuvant Ang-(1-7) may attenuate cardiac fibrosis and toxicity induced by Dox administration.

Abstract P638: Muscadine Grape Seed Extract Improves Glucose Handling in Female but not Male Hypertensive (mRen2)27 Rats

Muscadine grapes ( Vitis rotundifolia ) are enriched in polyphenols and other flavan-3-ols that may potentially convey cardiovascular benefit through the antioxidant properties of these compounds. In the current study, we established the effects of a muscadine grape extract (MGE, Piedmont Research and Development Corp.) on blood pressure and metabolic function in 20 week-old female and male hemizygous (mRen2)27 transgenic rats, an Ang II-AT 1 R-dependent model of hypertension. Littermates were treated with MGE (0.2 mg/mL) in the drinking water for 6 weeks (n = 7; male and n=5; female); controls were given water only (n = 7; male and n = 6; female). Intraperitoneal glucose tolerance test (IPGTT) assessed glucose metabolism and serum levels of glucose and insulin were also determined. There were no significant differences between the control and MGE-treated groups for either sex in systolic blood pressure (males: 168 ± 5 vs. 179 ± 4 mmHg; females: 183 ± 5 vs. 162 ± 11 mmHg) or body weight (males: 513 ± 12 vs. 508 ± 22 g; females: 297 ± 4 vs. 294 ± 89 g). The glucose response (area under the curve - AUC) in the female MGE-treated group was markedly lower compared to the untreated controls; however, MGE elicited no effect on the glucose AUC in males (see figure). Although MGE did not influence serum insulin AUC in males or females, the MGE-treated females exhibited a trend for a lower glucose-insulin index. We conclude that MGE intake improves glucose utilization in adult female hypertensive rats independent of changes in blood pressure or body weight. The mechanism(s) underlying the differential response to MGE between the female and male (mRen2)27 transgenic remain to be established

Abstract 1237: Anti-cancer activity of a stable, orally active angiotensin-(1-7) analog

Angiotensin-(1-7) [Ang-(1-7)] is an endogenous, peptide hormone that reduces tumor growth through effects on proliferation, inflammation, angiogenesis, fibrosis and metastasis. Ang-(1-7) mediates biological responses by activating mas, a unique G protein-coupled receptor, thereby providing specific targeted actions when used as a therapeutic agent. Unfortunately, Ang-(1-7) has unfavorable pharmacokinetic properties, resulting in a plasma half-life of about 30 min. In this study, TCAng05, a modified cyclic analog of Ang-(1-7), was compared to the parent compound Ang-(1-7) for efficacy, stability, and oral bioavailability. Ang-(1-7) or TCAng05 was incubated with human A549 lung or MDA-MB-231 breast cancer cells for 6 to 10 days, to assess the effect on tumor cell growth. A single dose of TCAng05 significantly reduced the growth of both MDA-MB-231 and A549 cells, while daily doses of Ang-(1-7) were required due to rapid degradation. Growth inhibition by either compound was blocked by the Ang-(1-7) receptor antagonist D-Ala7-Ang-(1-7) [Dala], showing a receptor-mediated response. Ang-(1-7) was rapidly degraded following incubation in rat plasma with a half-life of about 30 min, while TCAng05 was stable under the same conditions for approximately 50 h. The oral efficacy of TCAng05 to inhibit tumor growth in vivo was assessed by injecting 4T1 cells into the mammary fat pad of BALB/C mice. Once the tumors reached 100 mm3, the mice received daily gavage of TCAng05 at 12 μg/kg/day (low), 60 μg/kg/day (medium) or 300 μg/kg/day (high). Tumors in mice with no treatment continued to grow until sacrifice at day 19, reaching a size of 671.2 ± 127.2 mm3. Oral treatment with TCAng05 at the medium or high dose reduced tumor volume, by 56.8% and 43.6%, respectively, to final tumor volumes of 289.7 ± 64.2 mm3 and 378.3 ± 151.2 mm3. Tumor weight was also reduced by treatment with the medium or high dose of oral TCAng05. TCAng05 had no effect on mouse weight, heart or kidney weight, indicating that oral administration of the Ang-(1-7) analog was well-tolerated. TCAng05 caused a dose-dependent decrease in Ki67 immunoreactivity in tumor tissue sections from mice treated with the analog, suggesting reduced tumor cell proliferation. TCAng05 administration to mice with breast tumors also caused a significant decrease in tumor blood vessel density, as measured by CD34 labeling, suggesting that the analog inhibits angiogenesis to decrease tumor size. Collagen staining with Picrosirius red was markedly decreased in human breast tumor xenografts by oral administration of TCAng05, demonstrating that the analog reduces tumor associated fibrosis. These results indicate that oral administration of TCAng05 to mice with breast tumors reduced tumor size, by decreasing tumor cell proliferation, angiogenesis and fibrosis, as previously observed with the native Ang-(1-7), and suggest that the modified analog may serve as an effective, orally active, targeted chemotherapeutic.

Citation Format: Patricia E. Gallagher, Kenneth A. Gruber, Michael Callahan, E. Ann Tallant. Anti-cancer activity of a stable, orally active angiotensin-(1-7) analog. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1237.

Medullary Endocannabinoids Contribute to the Differential Resting Baroreflex Sensitivity in Rats with Altered Brain Renin-Angiotensin System Expression

CB₁ cannabinoid receptors are expressed on vagal afferent fibers and neurons within the solitary tract nucleus (NTS), providing anatomical evidence for their role in arterial baroreflex modulation. To better understand the relationship between the brain renin-angiotensin system (RAS) and endocannabinoid expression within the NTS, we measured dorsal medullary endocannabinoid tissue content and the effects of CB₁ receptor blockade at this brain site on cardiac baroreflex sensitivity (BRS) in ASrAOGEN rats with low glial angiotensinogen, normal Sprague-Dawley rats and (mRen2)27 rats with upregulated brain RAS expression. Mass spectrometry revealed higher levels of the endocannabinoid 2-arachidonoylglycerol in (mRen2)27 compared to ASrAOGEN rats (2.70 ± 0.28 vs. 1.17 ± 0.09 ng/mg tissue; P < 0.01), while Sprague-Dawley rats had intermediate content (1.85 ± 0.27 ng/mg tissue). Microinjection of the CB₁receptor antagonist SR141716A (36 pmol) into the NTS did not change cardiac BRS in anesthetized Sprague-Dawley rats (1.04 ± 0.05 ms/mmHg baseline vs. 1.17 ± 0.11 ms/mmHg after 10 min). However, SR141716A in (mRen2)27 rats dose-dependently improved BRS in this strain: 0.36 pmol of SR141716A increased BRS from 0.43 ± 0.03 to 0.71 ± 0.04 ms/mmHg (P < 0.001), and 36 pmol of SR141716A increased BRS from 0.47 ± 0.02 to 0.94 ± 0.10 ms/mmHg (P < 0.01). In contrast, 0.36 pmol (1.50 ± 0.12 vs. 0.86 ± 0.08 ms/mmHg; P < 0.05) and 36 pmol (1.38 ± 0.16 vs. 0.46 ± 0.003 ms/mmHg; P < 0.01) of SR141716A significantly reduced BRS in ASrAOGEN rats. These observations reveal differential dose-related effects of the brain endocannabinoid system that influence cardiovagal BRS in animals with genetic alterations in the brain RAS.

Angiotensin-(1-7) Attenuates Skeletal Muscle Fibrosis and Stiffening in a Mouse Model of Extremity Sarcoma Radiation Therapy

BACKGROUND

Radiation-induced fibrosis (RIF) of musculoskeletal tissue is a common complication of radiation therapy for extremity soft-tissue sarcoma, with no standardized strategy for prevention and treatment. Angiotensin-(1-7) (Ang-[1-7]), a well-tolerated endogenous heptapeptide hormone with antitumor and antifibrotic properties, was tested as a radioprotectant for RIF and stiffening of irradiated muscles.

METHODS

Male CD-1 mice were randomized to one of three treatment groups: control, simulated sarcoma radiation therapy to the gastrocnemius and soleus muscles, or radiation therapy along with continuous Ang-(1-7) delivery initiated three days before radiation therapy. The biologically equivalent dose of radiation (∼100.3 Gy) absorbed by normal musculature during the course of radiation therapy for extremity sarcoma was delivered by means of four dose fractions of 7.3 Gy over two weeks. Fibrosis (n = 5 per group) and mechanical properties (n = 4 to 6 per group) of the muscles were measured at six weeks and four months after radiation therapy, and the intramuscular concentration of the profibrotic cytokines transforming growth factor-beta (TGF-β) and connective tissue growth factor (CTGF) (n = 8 to 10 per group) were measured at six weeks.

RESULTS

Interstitial (p < 0.01) and perivascular (p < 0.05) fibrosis increased significantly in the muscles treated with radiation therapy alone versus the nonirradiated controls at both six weeks (interstitial, +89%; perivascular, +112%) and four months (interstitial, +154%; perivascular, +88%). The muscles treated with radiation alone also exhibited increased tension (p < 0.01) versus nonirradiated controls at both six weeks (+779%) and four months (+1761%) when placed under 5% strain, and at four months (+1390%; p < 0.001) under 10% strain. At four months, muscle stiffness had increased in the mice treated with radiation therapy alone (+90%; p = 0.002) compared with nonirradiated controls. TGF-β production was also greater in this group at six weeks (+37%; p = 0.06) versus control. Ang-(1-7) administration prevented RIF and stiffening, with no differences observed for any other outcome between those receiving radiation therapy with Ang-(1-7) and the nonirradiated controls. Likewise, Ang-(1-7) mitigated the increase in TGF-β and CTGF concentration from radiation therapy.

CONCLUSIONS

Ang-(1-7) attenuated RIF, stiffening, and production of profibrotic cytokines that were elevated in mouse skeletal muscles after simulated radiation therapy for extremity sarcoma.

CLINICAL RELEVANCE

Ang-(1-7) may serve as a potential therapy for the prevention of RIF in patients who require radiation therapy as adjuvant treatment for soft-tissue sarcoma.

Downregulation of apelin in the human placental chorionic villi from preeclamptic pregnancies

The role of the endogenous apelin system in pregnancy is not well understood. Apelin's actions in pregnancy are further complicated by the expression of multiple forms of the peptide. Using radioimmunoassay (RIA) alone, we established the expression of apelin content in the chorionic villi of preeclamptic (PRE) and normal pregnant women (NORM) at 36-38 wk of gestation. Total apelin content was lower in PRE compared with NORM chorionic villi (49.7±3.4 vs. 72.3±9.8 fmol/mg protein; n=20-22) and was associated with a trend for lower preproapelin mRNA in the PRE. Further characterization of apelin isoforms by HPLC-RIA was conducted in pooled samples from each group. The expression patterns of apelin peptides in NORM and PRE villi revealed little or no apelin-36 or apelin-17. Pyroglutamate apelin-13 [(Pyr1)-apelin-13] was the predominant form of the peptide in NORM and PRE villi. Angiotensin-converting enzyme 2 (ACE2) activity was higher in PRE villi (572.0±23.0 vs. 485.3±24.8 pmol·mg(-1)·min(-1); n=18-22). A low dose of ANG II (1 nM; 2 h) decreased apelin release in NORM villous explants that was blocked by the ANG II receptor 1 (AT1) antagonist losartan. Moreover, losartan enhanced apelin release above the 2-h baseline levels in both NORM and PRE villi (P<0.05). In summary, these studies are the first to demonstrate the lower apelin content in human placental chorionic villi of PRE subjects using quantitative RIA. (Pyr1)-apelin-13 is the predominant form of endogenous apelin in the chorionic villi of NORM and PRE. The potential mechanism of lower apelin expression in the PRE villi may involve a negative regulation of apelin by ANG II.

Angiotensin-(1-7) prevents angiotensin II-induced fibrosis in cremaster microvessels

OBJECTIVE

The effect of the heptapeptide hormone Ang-(1-7) on microvascular fibrosis in rats with Ang II-induced hypertension was investigated, since vascular fibrosis/remodeling plays a prominent role in hypertension-induced end-organ damage and Ang-(1-7) inhibits vascular growth and fibrosis.

METHODS

Fibrosis of cremaster microvessels was studied in male Lewis rats infused with Ang II and/or Ang-(1-7).

RESULTS

Ang II elevated systolic blood pressure by approximately 40 mmHg, while blood pressure was not changed by Ang-(1-7). Ang II increased perivascular fibrosis surrounding 20-50 μm arterioles as well as interstitial fibrosis; coadministration of Ang-(1-7) prevented the increases in fibrosis. The fibrotic factor CTGF and phospho-Smad 2/3, which upregulates CTGF, were increased by Ang II; this effect was prevented by coadministration of Ang-(1-7). Although TGF-β phosphorylates Smad 2/3, TGF-β was no different among treatment groups. In contrast, Ang II increased the MAP kinase phospho-ERK1/2, which also phosphorylates Smad; p-ERK was reduced by Ang-(1-7). Ang-(1-7), in the presence or absence of Ang II, upregulated the MAP kinase phosphatase DUSP1.

CONCLUSIONS

These results suggest that Ang-(1-7) increases DUSP1 to reduce MAP kinase/Smad/CTGF signaling and decrease fibrosis in resistance arterioles, to attenuate end-organ damage associated with chronic hypertension.

Abstract 4981: Angiotensin-(1-7) targets c-Met signaling by up-regulating the phosphatase PTP1b to reduce triple negative breast cancer

Triple negative breast cancer (TNBC) is an aggressive form of breast cancer with no known targeted therapies, since the tumors cells lack expression of the estrogen receptor and do not overexpress the HER2/Neu oncoprotein. Our laboratory showed that angiotensin-(1-7) [Ang-(1-7)], an endogenous seven amino acid peptide hormone, specifically activates the G protein-coupled receptor mas to inhibit the growth of lung, breast and prostate cancer cells and tumors. Using the 4T1 syngeneic mouse TNBC model, we examined the molecular signaling involved in the anti-tumor effects of Ang-(1-7). Ang-(1-7) significantly reduced tumor volume when compared to the control group (a 46% reduction by day 18, n = 6-7, p&lt;0.05), with a concomitant decrease in tumor weight (2.0±0.3 g in untreated mice vs. 1.3±0.1 g in treated mice, p&lt;0.05). A significant reduction in the proliferation marker Ki67 was observed in tumors from Ang-(1-7)-treated mice compared to tumors from untreated mice (18.1±3.7 Ki67(+) cells vs 103.9±17.2, p&lt;0.005). Hepatocyte growth factor/scatter factor (HGF/SF) is a potent inducer of cell proliferation and cancer cell invasion by activating the receptor tyrosine kinase (RTK) c-Met and HGF/SF/c-Met signaling is elevated in TNBC. Ang-(1-7) attenuates c-Met RTK activation by HGF [phospho-c-Met(Y1234/1235)] in human MDA-MB-231 and mouse 4T1 TNBC cells by 30.3% (p&lt;0.001) and 32.1% (p&lt;0.005), respectively. The phosphatase PTP1b, a negative regulator of c-Met RTK activation, was significantly up-regulated by 75% in response to Ang-(1-7) treatment in the 4T1 cells (from 0.8±0.1 to 1.4±0.1, p&lt;0.05), suggesting that the heptapeptide hormone increases PTP1b to negatively regulate c-Met signaling. A significant decrease in immunoreactive phospho-c-Met(Y1234/1235) was also observed in 4T1 tumors treated with Ang-(1-7) as compared to untreated tumors (from 47.0 to 19.7% of field, n = 5, p&lt;0.05). The Ang-(1-7)-mediated suppression of HGF/SF-mediated c-Met activation was abrogated by D-alanine7-Ang-(1-7) [D-Ala], a mas receptor antagonist. In agreement with the Ang-(1-7)-mediated reduction of the tumor volume of 4T1 tumors, HGF-induced activation of the MAPKs ERK1 and ERK2 was reduced by the heptapeptide hormone in vitro (by 59.7 and 74.8%, respectively, n = 5). Further, Ang-(1-7) treatment significantly attenuated HGF/SF-stimulated cell invasion through Matrigel (by 53±2, n = 8, p&lt;0.05 compared to HGF/SF stimulation); this effect was abrogated by the mas receptor antagonist D-Ala. Collectively, our data suggest that Ang-(1-7) in part suppresses the progression of triple negative breast tumors by activating the mas receptor to upregulate the phosphatase PTP1b and attenuate HGF/SF-induced c-Met activation, resulting in decreased ERK1/2 signaling, reduced tumor growth and diminished cell invasion, providing support for the use of Ang-(1-7) as a novel therapeutic agent for patients with TNBC.

Citation Format: Guorui Deng, Linda Metheny-Barlow, Patricia E. Gallagher, E. Ann Tallant. Angiotensin-(1-7) targets c-Met signaling by up-regulating the phosphatase PTP1b to reduce triple negative breast cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4981. doi:10.1158/1538-7445.AM2015-4981

Abstract 4489: Angiotensin-(1-7) prevents fibrosis in doxorubicin-treated rats

Anthracyclines such as doxorubicin (Dox) are effective chemotherapeutic agents for multiple malignancies, including childhood leukemias and sarcomas. Despite the efficacy of these agents, anthracyclines can result in cumulative dose-dependent cardiac toxicity that manifests as cardiomyopathy with marked myocardial hypertrophy and fibrosis. This cardiotoxicity culminates in reduced ejection fraction, fractional shortening, and cardiac output, leading to congestive heart failure. Consequently, there is an unmet need for adjunct therapies to temper anthracycline-induced cardiotoxicity and enhance long-term quality of life in patients treated with anthracyclines, especially pediatric cancer patients. Angiotensin-(1-7) [Ang-(1-7)] is an endogenous seven amino acid peptide hormone of the renin-angiotensin system with cardioprotective properties. Studies by us and others showed that Ang-(1-7) improved cardiac function as well as reduced cardiac hypertrophy and fibrosis in various animal models. In this study, we assessed whether adjunct Ang-(1-7) (24 μg/kg/hr) attenuates cardiotoxicity that results from acute (6 week) exposure of 5 week-old Sprague-Dawley rats to Dox, administered weekly at a cumulative dose of 15 mg/kg. Body weight was reduced in rats treated with Dox, in the presence or absence of Ang-(1-7); however, the heart weight/body weight ratio was increased in Dox-treated rats while co-administration with Ang-(1-7) prevented the Dox-mediated increase. Myocyte cross-sectional area was not changed by administration of Dox or Ang-(1-7). Dox administration caused significant increases in cardiac fibrosis (an increase in interstitial fibrosis from 0.9±0.1% to 1.5±0.2%, p&lt;0.001 compared to sham, and perivascular fibrosis from 16.0±1.1% to 23.6±3.0%, p&lt;0.05; n = 3-8), which was prevented by co-administration of Ang-(1-7). Interstitial and perivascular fibrosis in rats treated with Ang-(1-7) or with Dox/Ang-(1-7) was no different than in sham animals. The Dox-mediated increase in cardiac fibrosis and the anti-fibrotic effects of Ang-(1-7) co-administration may account for the changes in heart weight/body weight, since doxorubicin did not alter the size of cardiac myocytes. Cardiac function was assessed using a Vevo 2100 small animal ultrasound system, at baseline and following treatment. Doxorubicin reduced ejection fraction, fractional shortening and cardiac output compared to sham or Ang-(1-7) alone; co-administration of Ang-(1-7) with Dox tended to prevent the Dox-mediated reductions in cardiac contractility. The Dox-mediated increase in fibrosis may contribute to the reduced cardiac contractility and the Ang-(1-7)-mediated reduction in Dox-induced fibrosis may account for the improvement in contractility in rats co-administered Dox and Ang-(1-7). These results suggest that Ang-(1-7) may be effective in preventing Dox-induced cardiac fibrosis and may attenuate acute cardiac toxicity induced by Dox administration.

Citation Format: Omeed A. Rahimi, Sharon M. Castellino, Cheryl E. Cammock, E Ann Tallant, Patricia E. Gallagher. Angiotensin-(1-7) prevents fibrosis in doxorubicin-treated rats. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4489. doi:10.1158/1538-7445.AM2015-4489

Abstract 4563: Muscadine grape extract reduces lung carcinogenesis in female mice exposed to 3-methylcholanthrene in utero

The developing fetus is highly sensitive to the carcinogenic effects of dietary and environmental carcinogens in cigarette smoke, charbroiled foods and air pollution following transplacental exposure. Oxidative metabolism of toxicants by both maternal and fetal tissue causes DNA damage which can ultimately result in the initiation of childhood cancers. Due to the latency of cancer formation, in utero exposure to carcinogens may even predispose the individual to cancers developing later in life. The goal of this study is to determine whether a proprietary muscadine grape extract (MGE) effectively reduces lung tumor formation in the fetus following transplacental exposure to a polycyclic hydrocarbon. The muscadine grape (Vitis rotundifolia) has a distinct phytochemical composition compared to other grape varieties and limited reports indicate that the extract has potential anti-tumor activity. BALB/c male mice were mated to C57BL/6 female mice to serve as a model for in utero exposure to environmental toxicants. The pregnant mice were treated on the 17th day of gestation by intraperitoneal injection with a 45 mg/kg dose of 3-methylcholanthrene dissolved in olive oil, to induce lung tumors in the fetus. An injection of the olive oil vehicle (0.5 mL/0.35 kg) served as the control. Day 0 was considered as the first day when the vaginal plug was detected. After weaning, cohorts of mice received drinking water alone or water with MGE (approximately 1.0 mg phenolics/25 g mouse) and were sacrificed at 12 months of age. Although all of the mice developed lung tumors, MGE significantly reduced tumor burden in female mice by approximately 48% as compared to the tumor tissue found in control mice drinking regular water (12.4 ± 1.9 g versus 6.5 ± 1.2 g, n = 26-32, p = 0.014). In addition, tumor multiplicity was higher in control mice as compared to MGE-treated animals (6.8 ± 0.4 observed tumors versus 4.2 ± 0.5 observed tumors, n = 26-32, p = 0.0001). Tumor tissue sections from mice administered MGE had a significant decrease in proliferating cell nuclear antigen as compared to tumors from control animals (22.4 ± 1.8 versus 14.2 ± 1.3, p = 0.0009), suggesting that in part MGE reduces tumor burden by decreasing tumor cell proliferation. Lung tumor sections from female mice drinking regular water or MGE were incubated with an antibody to the endothelial cell marker, CD34, and vessels were identified by a combination of morphology and positive CD34 immunoreactivity. MGE significantly reduced blood vessel density in lung tumor tissue as compared to female mice drinking regular water (20.5 ± 2.2 versus 11.3 ± 1.3, p = 0.0012), suggesting that the grape extract inhibits angiogenesis. These results indicate that MGE reduces both tumor proliferation and angiogenesis, leading to a decrease in tumor burden and multiplicity. Thus, MGE may represent a novel nutraceutical for the prevention of lung tumors induced by in utero exposure to environmental toxicants.

Citation Format: Brooke E. Porter, Joseph E. Moore, Mark S. Miller, E. Ann Tallant, Patricia E. Gallagher. Muscadine grape extract reduces lung carcinogenesis in female mice exposed to 3-methylcholanthrene in utero. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4563. doi:10.1158/1538-7445.AM2015-4563

Abstract 2825: Prevention of breast tumor growth by an extract from the muscadine grape

Grape extracts have garnered attention as chemopreventive agents due their anti-proliferative, anti-inflammatory and anti-oxidant properties. The muscadine grape (Vitis rotundifolia) has a distinct phytochemical composition compared to other grape varieties. The current study examines the preventive effects of a proprietary muscadine grape extract (MGE) on breast cancer formation. The proliferation of actively growing human ER+ or triple negative breast cancer cells was significantly reduced by MGE from grape seeds or skins with an associated decrease in phospho-ERK, suggesting that MGE inhibits breast cancer cell proliferation through a reduction in activation of growth-promoting kinases. Female FVB-Tg(MMTV)NKAMul/J transgenic mice with an activated rat Erbb2 oncogene expressed specifically in the mammary gland (c-neu mice) form mammary tumors by 6-8 months of age. c-Neu mice were treated with MGE in the drinking water (approximately 1.0 mg phenolics/25 g mouse) beginning at weaning and were sacrificed at 7½ months of age. No changes were observed in eating or drinking habits or in gross body, heart or kidney weight, suggesting that the MGE was well tolerated. Although all of the mice developed breast tumors, MGE significantly reduce tumor burden compared to the tumor tissue in mice drinking regular water (9.2±1.2 g versus 3.6±1.4 g, p = 0.001, n = 8-10). A group of c-Neu mice were also sacrificed at 4 months of age, once tumors were palpable, to assess tumor multiplicity. Both tumor burden (1.4±.3 g versus 0.3±0.1 g, p = 0.007) and tumor multiplicity (11.8±2.1 versus 5.1±0.9, p = 0.013, n = 6-11) were reduced in mice treated with MGE. Tumor tissue sections from mice administered MGE had a significant decrease in the proliferation marker Ki67 compared to tumors from control animals [310±92 versus 166±70 immunoreactive cells/field, p = 0.002], in agreement with the reduction in proliferation observed in vitro. Tumor sections from c-neu mice were incubated with an antibody to the endothelial cell marker, CD34, and vessels were identified by a combination of morphology and positive CD34 immunoreactivity; MGE significantly reduced blood vessel density in breast tumor tissue compared to tumors from mice drinking regular water [5.7±0.6 versus 3.6±0.9, p = 0.022], suggesting that the grape extract attenuates tumor angiogenesis. Interstitial tumoral fibrosis was quantified in breast tumor tissue sections using picrosirius red, a nonspecific collagen stain. MGE treatment markedly decreased interstitial fibrosis as compared to the tumors from control animals [2.79±0.70% versus 0.14±0.04%, p = 0.0005], indicating that the extract reduces cancer-associated fibrosis in breast tumors. Taken together, these studies suggest that MGE reduces both breast tumor burden and multiplicity, through decreasing proliferation, angiogenesis and fibrosis, suggesting that extracts from muscadine grapes may represent a novel nutraceutical for the prevention of breast cancer.

Citation Format: Patricia E. Gallagher, E. Ann Tallant. Prevention of breast tumor growth by an extract from the muscadine grape. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2825. doi:10.1158/1538-7445.AM2015-2825

Local uterine Ang-(1-7) infusion augments the expression of cannabinoid receptors and differentially alters endocannabinoid metabolizing enzymes in the decidualized uterus of pseudopregnant rats

BACKGROUND

Endocannabinoids (ECs) are important contributors to implantation and decidualization and are suppressed in early pregnancy. Elevated levels of anandamide (AEA), the endogenous ligand for the CB1 and CB2 receptors (R), interfere with receptivity of the blastocyst. Ang-(1-7) is down-regulated in the implantation site (IS) in normal pregnancy at day 7 of gestation. We determined the effects of intra-uterine angiotensin-(1-7) [Ang-(1-7)] (24 microg/kg/h) or vehicle given into the left uterine horn on the ECs in the decidualized uterus.

METHODS

Ovariectomized rats were sensitized for the decidual cell reaction by steroid treatment and decidualization was induced by a bolus of oil injected into the left horn; the right horn served as a control.

RESULTS

Decidualization increased endometrial permeability (3.1+/-0.2 vs. 7.1+/-0.5 uterus/muscle of cpm of (125)I-BSA, p < 0.0001). VEGF mRNA was increased by the decidualization (1.4-fold, p < 0.05) and by Ang-(1-7) (2.0-fold, p < 0.001). CB1R mRNA was reduced by decidualization (2.7-fold, p < 0.001), but increased by Ang-(1-7) (1.9-fold, p < 0.05). CB2R mRNA was increased by decidualization (4-fold, p < 0.05) and by Ang-(1-7) (2.4-fold, p < 0.001). The enzyme metabolizing AEA, fatty acid amide hydrolase (FAAH), was reduced by decidualization (7.8 fold, p < 0.001) and unchanged by Ang-(1-7) (p > 0.05), whereas the enzyme metabolizing 2-arachidonoylglycerol, monoacyl glycerol lipase (MAGL), was unchanged by decidualization (p > 0.05) and increased by Ang-(1-7) (1.7 fold, p < 0.001).

CONCLUSIONS

These findings report for the first time that Ang-(1-7) augments the expression of CB1R, CB2R and MAGL in the decidualized uterus and thus may interfere with the early events of decidualization.

Abstract 542: Blockade of Angiotensin-(1-7)-mediated Vascular Remodeling by a CB2 Cannabinoid Receptor Antagonist

Angiotensin-(1-7) [Ang-(1-7)] inhibits vascular smooth muscle cell (VSMC) growth and reduces cardiac hypertrophy and vascular remodeling in Ang II-infused hypertensive rats. We previously showed that Ang-(1-7) increased the endocannabinoid 2-AG in VSMCs and that inhibition of VSMC growth by Ang-(1-7) was prevented by blockade of CB2 cannabinoid receptors. VSMCs isolated from mice with ablated CB2 receptors were treated with platelet-derived growth factor to stimulate growth; neither Ang-(1-7) nor the CB2 receptor agonist HU308 reduced VSMC growth (98.7±9.9% and 105.4±13.0% of stimulated growth, respectively, n = 3-6), suggesting that growth inhibition by Ang-(1-7) is mediated through activation of the CB2 receptor. Ang II-infused Sprague-Dawley rats were treated for 28 days with Ang-(1-7), in the presence or absence of the CB2 receptor antagonist SR144528, to determine whether CB2 receptor blockade prevents the Ang-(1-7)-mediated reductions in Ang II-stimulated cardiac hypertrophy and vascular remodeling. Systolic blood pressure was similar in both groups, before or after treatment (115±4.6 mmHg with SR144528 and 115.7±10.2 mmHg with Ang-(1-7)/SR144528 before treatment and 186.7±6.2 mmHg and 182.0±2.1 mmHg after Ang II treatment, respectively, n=4). Ang II increased the mean cross-sectional area of cardiac myocytes which was reduced 55% by Ang-(1-7); CB2 receptor blockade prevented the Ang-(1-7)-mediated reduction in myocyte size. Fibrosis (interstitial and perivascular) and vessel size (M/L) were unchanged by Ang-(1-7) in the presence of SR144528 compared to a 79%, 85% and 90% reduction of the Ang II-mediated increase in interstitial fibrosis, perivascular fibrosis and M/L, respectively, by Ang-(1-7) alone. Brain natriuretic peptide and atrial natriuretic peptide also were unchanged by Ang-(1-7) in the hearts of rats treated with Ang II and SR144528 compared to a 91% and 99% reduction by Ang-(1-7) in Ang II-treated rats. Thus, treatment with a CB2R antagonist blunts the anti-hypertrophic and anti-fibrotic responses to Ang-(1-7) in hypertensive Ang II-treated rats, independent of blood pressure, suggesting that the growth inhibitory properties of Ang-(1-7) involve a novel pathway which includes activation of the CB2 receptor.

Angiotensin-(1-7) prevents radiation-induced inflammation in rat primary astrocytes through regulation of MAP kinase signaling

About 500,000 new cancer patients will develop brain metastases in 2013. The primary treatment modality for these patients is partial or whole brain irradiation which leads to a progressive, irreversible cognitive impairment. Although the exact mechanisms behind this radiation-induced brain injury are unknown, neuroinflammation in glial populations is hypothesized to play a role. Blockers of the renin-angiotensin system (RAS) prevent radiation-induced cognitive impairment and modulate radiation-induced neuroinflammation. Recent studies suggest that RAS blockers may reduce inflammation by increasing endogenous concentrations of the anti-inflammatory heptapeptide angiotensin-(1-7) [Ang-(1-7)]. Ang-(1-7) binds to the AT(1-7) receptor and inhibits MAP kinase activity to prevent inflammation. This study describes the inflammatory response to radiation in astrocytes characterized by radiation-induced increases in (i) IL-1β and IL-6 gene expression; (ii) COX-2 and GFAP immunoreactivity; (iii) activation of AP-1 and NF-κB transcription factors; and (iv) PKCα, MEK, and ERK (MAP kinase) activation. Treatment with U-0126, a MEK inhibitor, demonstrates that this radiation-induced inflammation in astrocytes is mediated through the MAP kinase pathway. Ang-(1-7) inhibits radiation-induced inflammation, increases in PKCα, and MAP kinase pathway activation (phosphorylation of MEK and ERK). Additionally Ang-(1-7) treatment leads to an increase in dual specificity phosphatase 1 (DUSP1). Furthermore, treatment with sodium vanadate (Na3VO4), a phosphatase inhibitor, blocks Ang-(1-7) inhibition of radiation-induced inflammation and MAP kinase activation, suggesting that Ang-(1-7) alters phosphatase activity to inhibit radiation-induced inflammation. These data suggest that RAS blockers inhibit radiation-induced inflammation and prevent radiation-induced cognitive impairment not only by reducing Ang II but also by increasing Ang-(1-7) levels.

Abstract 499: Renal Endocannabinoids in Salt-Sensitive Hypertension of SHR

Recent evidence suggests that endocannabinoids (ECs) acting on two major cannabinoid receptors (CB 1 and CB 2 ) regulate blood pressure and cardiovascular and renal function in health and disease. However, there is no evidence of the role of ECs in the salt-induced renal damage in hypertensive subjects. In the present study we investigated changes in the content of two major ECs, 2-arachidonoylglycerol (2-AG) and anandamide ( N -arachidonoylethanolamine), and related functional changes in the kidneys of spontaneously hypertensive rats (SHR) in response to increased dietary salt intake. Male SHRs were given an 8% salt diet (HS; n=7), while their age-matched controls (C; n=7) received standard chow for 5 weeks. ECs were measured by UPLC/MS-MS methods on Applied Biosystems Mass Spectrometry Systems. After 5 weeks on a high salt diet, renal 2-AG (4.29 ± 0.40 vs. 3.32 ± 0.17 ng/mg; p<0.05) but not anandamide (2.12 ± 0.17 vs. 2.27 ± 0.07 pg/mg) increased in the salt-loaded SHR. Dietary salt excess increased mean arterial pressure (203 ± 5 vs. 171 ± 7 mmHg; p<0.05), urinary protein excretion (159 ± 37 vs. 22 ± 2 mg/day), and significantly decreased renal blood flow measured by flow probe (2.93 ± 0.55 vs. 6.67 ± 0.56 ml/min/mg; p<0.05) and glomerular filtration rate assessed by creatinine clearance (1.15 ± 0.14 vs. 1.77 ± 0.08 ml/min; p<0.05). Our previous study showed a reduction in CB 1 receptor mRNA while CB 2 receptor gene expression was increased in the kidney of salt-loaded SHR. Together these results suggest that alterations in renal ECs may play a significant role in the development of renal injury due to high dietary salt intake.

Abstract 465: The CB2 Cannabinoid Receptor Mediates the Anti-Proliferative Actions of Angiotensin-(1-7) in Vascular Smooth Muscle Cells

Therapeutic interventions to reduce vascular proliferation are critical for the effective treatment of hypertension-induced end-organ damage, restenosis and atherosclerosis. We showed that angiotensin-(1-7) [Ang-(1-7)] reduces neointimal formation following vascular injury and inhibits vascular growth, through activation of the AT7 receptor mas and production of arachidonic acid derivatives. Endocannaboids (ECs) derived from membrane phospholipids also inhibit vascular proliferation and reduce growth following vascular injury, by stimulation of the CB2 receptor. The impact of CB2 receptor blockade on the anti-proliferative actions of Ang-(1-7) was investigated to assess a potential interaction between the EC and Ang-(1-7)/mas receptor systems. Rat thoracic aortic vascular smooth muscle cells (VSMCs) were treated with platelet-derived growth factor (PDGF) to stimulate growth and incubated with Ang-(1-7), the AT7 receptor antagonist [D-alanine7]-angiotensin-(1-7) [Dala], the CB2 receptor agonist HU308 and/or the CB2 receptor antagonist AM630. PDGF-stimulated VSMC growth was markedly reduced by Ang-(1-7) (74 ± 6% of control, n = 10, p<0.0001) and this effect was blocked by Dala (116 ± 14% of control, n = 4; n.s.). The Ang-(1-7)-mediated reduction in growth was abolished by the CB2 receptor antagonist AM630 (136 ± 16% of control, n = 4; n.s.); AM630 alone had no effect. In contrast, the CB1 receptor antagonist AM281 did not prevent the inhibitory actions of Ang-(1-7) on VSMC growth. CB2 receptor activation by the agonist HU308 also reduced PDGF-stimulated VSMC proliferation to a similar extent as Ang-(1-7) (67 ± 4% of control, n = 5, p<0.001); Dala did not influence the response to HU308 (50 ± 10% of control, n = 5, p<0.005). Ang-(1-7) significantly increased the endogenous cannabinoid 2-arachidonoylglycerol (2-AG) by 48% in VSMC by 24 h (p<0.05, n = 4). We conclude that the growth inhibitory properties of Ang-(1-7) involve a novel pathway culminating in the downstream formation of 2-AG and subsequent activation of the CB2 receptor in VSMC. Thus, Ang-(1-7) and/or CB2 receptor activation may constitute a new and beneficial therapeutic strategy for the prevention of vascular proliferation that is prevalent in cardiovascular disease.

Abstract 543: Local Uterine Ang-(1-7) Infusion Augments Expression of Cannabinoid Receptors and Differentially Alters Endocannabinoid Metabolizing Enzymes in the Decidualized Uterus of Pseudopregnant Rats

Endocannabinoids (ECs) are important contributors to implantation and decidualization and are suppressed in early pregnancy. Elevated levels of anandamine (AEA), the endogenous ligand for the CB 1 and CB 2 receptor (R), interfere with receptivity of the blastocyst. Ang-(1-7) is present in the decidualized zones of the implantation site (IS) at early pregnancy and is down-regulated in the IS in normal pregnancy. We determined the effects of intra-uterine Ang-(1-7) on the EC system in the decidualized uterus. Ovariectomized rats were sensitized for the decidual cell reaction by steroid treatment. Decidualization was induced by infusion of phosphate buffered saline into the left horn (infused); the right horn was non-infused. Ang-(1-7) (24 μg/kg/hr) or vehicle was given into one of the two uterine horns. CB 1 R mRNA was reduced by decidualization but increased in the presence of Ang-(1-7) . CB 2 R mRNA was increased by decidualization and by Ang-(1-7) ( Figure). The enzyme metabolizing AEA, fatty acid amide hydrolase (FAAH), was reduced by decidualization (1.0 ± 0.07 vs. 0.13 ± 0.03 U, p<0.01) and remained reduced by Ang-(1-7), whereas the enzyme metabolizing 2-arachidonylglycerol, monoacyl glycerol lipase (MAGL), was unchanged by decidualization (1.06 ± 0.11 vs. 1.34 ± 0.13 U, ns) and increased by Ang-(1-7) (1.32 ± 0.19 vs. 2.27 ± 0.23 U, p<0.01). These findings report for the first time that Ang-(1-7) augments the expression of CB 1 R, CB 2 R and MAGL in the decidualized uterus. The effects of Ang-(1-7) to disrupt regulation of the EC system may interfere with the early events of decidualization, including alterations in angiogenesis, apoptosis, permeability, and receptivity.

Abstract C66: Angiotensin-(1-7) attenuates triple-negative breast cancer growth and progression through regulation of protein phosphatases

Triple-negative breast cancer is a highly aggressive and invasive tumor type which accounts for 15% of all breast cancers and disproportionately affects pre-menopausal women as well as African-American and Hispanic populations. Triple negative breast tumors show an increased risk for metastasis, due to over-activation of tumor-promoting signaling pathways, including the mitogen-activated protein kinase (MAPK) and PI3 kinase (PI3K)-Akt pathways. The limited available targeted therapies for triple negative breast cancer due to the lack of estrogen and progesterone receptor expression and unamplified human epidermal growth factor receptor 2 (HER2) levels indicate a clear need for novel targeted therapies for patients. Angiotensin-(1-7) [Ang-(1-7)] is an endogenous, seven amino acid peptide hormone of the renin-angiotensin system that activates the G protein-coupled receptor mas. Ang-(1-7) inhibited the growth of MDA-MB-231 human triple negative breast tumors growing in the mammary fat pads of athymic mice. The mean tumor volumes of saline- or Ang-(1-7)-treated mice were similar prior to the initiation of treatment (saline, 113.3±7.0 mm3; Ang-(1-7), 107.6±6.8 mm3). The tumor volume of mice treated with saline increased 4.4-fold over the 28 day treatment period; in contrast, the volume of tumors from mice administered Ang-(1-7) did not increase over the 28-day treatment period compared to tumor volume at the initiation of treatment. Cells in tumors from mice treated with saline showed abundant Ki67 immunoreactivity, while Ki67 immunoreactivity was reduced 51% in tumor cells from mice injected with Ang-(1-7). Ang-(1-7) significantly reduced the phosphorylation of ERK1 and ERK2 in triple negative breast tumors as compared to the phospho-modification of the enzymes in tumors from saline-treated mice, by 95.2% and 81.3%, respectively; no change in non-phosphorylated ERK1 and ERK2 was observed. The dual-specificity phosphatase DUSP1, or MKP-1, is a key phosphatase that regulates the activity of ERK1/ERK2. Ang-(1-7) significantly increased DUSP1 protein and mRNA in tumors of mice injected with Ang-(1-7) as compared to tumors from saline-treated mice. Incubation of human MDA-MB-231 triple negative breast cancer cells with an siRNA to DUSP1 prevented the reduction in ERK activation, demonstrating that the heptapeptide hormone up-regulates DUSP1 to reduce MAP kinase activities. Ang-(1-7) also attenuated PI3 kinase-Akt signaling in human triple negative breast tumors by up-regulating the Akt phosphatase PP2A (protein phosphatase 2A) 5-fold (n=4-5, p&lt;0.05). Incubation of MDA-MB-231 human triple negative breast cancer cells with Ang-(1-7) increased PP2A subunits--both the scaffolding A subunit (a 4-fold increase, n=3-4, p&lt;0.05) and the catalytic C subunit (a 2-fold increase, n=3-4, p&lt;0.05). The heptapeptide hormone also significantly inhibited the growth of 4T1 murine triple negative breast cancer cells (n=3, p&lt;0.05). The reduction in 4T1 cell growth was similarly associated with a 5-fold increase in PP2A-A and a 2-fold increase in PP2A-C (n=3-4, p&lt;0.05 and p&lt;0.01, respectively), with a concomitant 80 to 90% reduction in phospho-Akt at both the serine and threonine residues (n=3-4, p&lt;0.001 and p&lt;0.0001, respectively). Taken together, these results suggest that Ang-(1-7) may serve as a novel, targeted therapy for triple negative breast cancer by regulating protein phosphatases to reduce activation of protein kinase-mediated proliferative signaling cascades.

Citation Format: Patricia E. Gallagher, Alison L. Arter, David R. Soto-Pantoja, E. Ann Tallant. Angiotensin-(1-7) attenuates triple-negative breast cancer growth and progression through regulation of protein phosphatases. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Invasion and Metastasis; Jan 20-23, 2013; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2013;73(3 Suppl):Abstract nr C66.

Abstract B34: Angiotensin-(1-7) attenuates the proliferation of cancer-associated fibroblasts in triple negative breast cancer

The interaction between cancer cells and the surrounding microenvironment transforms the stroma into an abnormal phenotype, altering normal function, tissue architecture, cellular morphology, and extracellular matrix-cell interactions that directly contribute to formation of neoplasia. About 80% of reactive stroma associated with breast carcinoma is comprised of activated myofibroblasts or cancer-associated fibroblasts which secrete extracellular matrix proteins resulting in the desmoplasia that is associated with advanced breast tumor progression. Cancer-associated fibroblasts, transformed by cytokines such as transforming growth factor-β (TGF-β), secrete tumor promoting growth factors and extracellular matrix components, to promote tumor initiation, growth, and metastases. Inhibition of cancer-associated fibroblast proliferation and function may be an effective therapeutic strategy, since these cells play a vital role in carcinogenesis. Angiotensin-(1-7) [Ang-(1-7)] is an endogenous, seven amino acid peptide hormone of the renin-angiotensin system with anti-proliferative and anti-fibrotic properties. We showed that Ang-(1-7) inhibited the growth of MDA-MB-231 human triple negative breast tumors growing in the mammary fat pads of athymic mice with a concomitant 3-fold decrease in interstitial tumor fibrosis (n=9-11, p&lt;0.0001). Cancer-associated fibroblasts were isolated from orthotopic breast tumors, to assess the effect of Ang-(1-7) on fibroblast proliferation. The isolated tumoral fibroblasts stained positive for fibronectin, vimentin, collagen I, and β-smooth muscle actin, confirming that the isolated cells were activated myofibroblasts. Ang-(1-7) significantly reduced the growth of cancer-associated fibroblasts isolated from orthotopic triple negative breast tumors (n=4-5, p&lt;0.05). The decrease in cancer-associated fibroblast proliferation was accompanied by attenuation of the activation of the growth-promoting mitogen-activated protein kinases (MAPK) ERK1 and ERK2 (n=3, p&lt;0.001) as quantified by Western blot hybridization. In contrast, incubation of the heptapeptide hormone resulted in a 2.5-fold increase in the MAPK phosphatase DUSP1 (dual specificity phosphatase 1) in cancer-associated fibroblasts (n=3, p&lt;0.05). These studies suggest that Ang-(1-7) promotes the dephosphorylation of MAPK by up-regulating DUSP1 to reduce this proliferative signaling pathway in cancer-associated fibroblasts and prevent tumor growth. TGF-β is a potent stimulator of fibroblast activation and plays an important role in promoting fibrosis, including activation of the MAP kinase pathway to stimulate fibroblast proliferation. TGF-β activates tumor-promoting cancer-associated fibroblasts by phosphorylation of Smad2/3 which translocates to the nucleus to induce pro-fibrotic gene expression. Stimulation of the Smad signaling pathway by TGF-β results in extracellular matrix protein synthesis and deposition as well as its own production, creating an autocrine cycle of fibroblast activation and extracellular matrix deposition. TGF-β was quantified by Western blot hybridization in protein homogenates from myofibroblasts isolated from orthotopic breast tumors. TGF-β stimulation of cancer-associated fibroblasts significantly increased phospho-Smad2/3 which was reduced approximately 60% by treatment with Ang-(1-7) (n=3, p&lt;0.001), indicating that the heptapeptide inhibits both the growth of stromal fibroblasts as well as the signaling pathways that participate in extracellular matrix protein production. These findings suggest that Ang-(1-7) may serve as a first-in-class chemotherapeutic agent for triple negative breast cancer in part through a reduction in the proliferation and function of cancer-associated fibroblasts in the tumor microenvironment.

Citation Format: Alison L. Arter, Patricia E. Gallagher, E. Ann Tallant. Angiotensin-(1-7) attenuates the proliferation of cancer-associated fibroblasts in triple negative breast cancer. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Invasion and Metastasis; Jan 20-23, 2013; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2013;73(3 Suppl):Abstract nr B34.

Angiotensin-(1-7) attenuates metastatic prostate cancer and reduces osteoclastogenesis

BACKGROUND

Angiotensin-(1-7) [Ang-(1-7)] is an endogenous, heptapeptide hormone with anti-proliferative and anti-angiogenic properties. The primary objective of this study was to determine whether Ang-(1-7) effectively reduces prostate cancer metastasis in mice.

METHODS

Human PC3 prostate cancer cells were injected into the aortic arch via the carotid artery of SCID mice pre-treated with Ang-(1-7) or injected into the tibia of athymic mice, administered Ang-(1-7) for 5 weeks beginning 2 weeks post-injection. Tumor growth and volume were determined by bioluminescent and magnetic resonance imaging. The presence of tumors was confirmed by hematoxylin and eosin staining; TRAP histochemistry was used to identify osteolytic lesions. The effect of Ang-(1-7) on osteoclastogenesis was assessed in differentiated bone marrow cells.

RESULTS

Pre-treatment with Ang-(1-7) prevented metastatic tumor formation following intra-aortic injection of PC3 cells, while 83% of untreated mice developed tumors in metastatic sites. Circulating VEGF was significantly higher in control mice compared to mice administered Ang-(1-7). A 5-week regimen of the heptapeptide hormone attenuated intra-tibial tumor growth; Ang-(1-7) was significantly higher in the tibia of treated mice than in control animals. Osteoclastogenesis was reduced by 50% in bone marrow cells differentiated in the presence of Ang-(1-7), suggesting that the heptapeptide hormone prevents the formation of osteolytic lesions to reduce tumor survival in the bone microenvironment.

CONCLUSIONS

These findings suggest that Ang-(1-7) may serve as an anti-angiogenic and anti-metastatic agent for advanced prostate cancer. By extension, the heptapeptide hormone may provide effective therapy for bone metastasis produced from primary tumors of the lung and breast.

Angiotensin-(1-7) reduces proliferation and angiogenesis of human prostate cancer xenografts with a decrease in angiogenic factors and an increase in sFlt-1

BACKGROUND

Prostate cancer is the most frequently diagnosed malignancy and the second-leading cause of cancer death in men. The purpose of this study was to determine the anti-proliferative and anti-angiogenic efficacy of angiotensin-(1-7) [Ang-(1-7)], an endogenous peptide hormone, in human prostate cancer xenografts.

METHODS

Human LNCaP prostate cancer cells were injected into the flank of athymic mice and tumors were treated with Ang-(1-7) for 54 days. Tumor growth and angiogenesis were determined by immunohistochemistry and western blot hybridization.

RESULTS

Ang-(1-7) markedly reduced the volume and wet weight of LNCaP xenograft tumors. Histological analysis of tumor sections from saline-treated mice showed increased Ki67 immunoreactivity and enhanced phosphorylation of the MAP kinases ERK1/2 compared to tumors from Ang-(1-7)-treated mice, suggesting that the heptapeptide reduces cell proliferation. Intratumoral vessel density was decreased in Ang-(1-7)-treated mice with an associated reduction in vascular endothelial growth factor (VEGF) and placental growth factor (PlGF), suggesting that the heptapeptide attenuates vascularization by reducing angiogenic factors. Ang-(1-7) administration markedly increased the soluble fraction of VEGF receptor 1 (sFlt-1), with a concomitant reduction in VEGF receptors 1 and 2. sFlt-1 serves as a decoy receptor that traps VEGF and PlGF, making the ligands unavailable to membrane-bound VEGF receptors and preventing activation of pro-angiogenic signaling.

CONCLUSIONS

The decrease in PlGF and VEGF coupled with the increase in sFlt-1 suggests that Ang-(1-7) may serve as a novel anti-angiogenic therapy for prostate cancer. Further, the pleiotropic mechanisms of action by Ang-(1-7) may limit angiogenic resistance that occurs with VEGF inhibitors or receptor blockers.

Abstract 512: Angiotensin-(1-7) Attenuates PDGF-dependent Migration of Vascular Smooth Muscle Cells

Over one million percutaneous coronary intervention (PCI) procedures are performed each year and restenosis, the narrowing of the vessel lumen due to vascular damage, occurs in more than 40% of these patients. Previous studies by our laboratory demonstrated that infusion of angiotensin-(1-7) [Ang-(1-7)], an anti-proliferative peptide hormone of the renin-angiotensin system, attenuated neointimal formation after vascular injury which was associated with reduced vascular smooth muscle cell (VSMC) proliferation. However, prevention of restenosis after PCI requires inhibition of both VSMC proliferation and migration. In this study, the effect of Ang-(1-7) on VSMC migration was investigated to determine whether a decrease in VSMC migration also represents a component of the heptapeptide-induced reduction in neointimal formation. Platelet-derived growth factor (PDGF), a potent stimulus for VSMC migration, increased chemotaxis in a modified Boyden’s chamber; PDGF stimulated chemotaxis 228% over random migration and pre-treatment with Ang-(1-7) reduced the PDGF-mediated migration to 132% over random movement, a reduction of 42.1% (n=6, p<0.05). PDGF also stimulated directional migration in a wounding assay, by 600% over random migration; pre-treatment with Ang-(1-7) reduced directional migration in response to PDGF to 317% of random migration, a 40.4% decrease (n=5, p>0.01). The reduction in PDGF-mediated migration by Ang-(1-7) was associated with a significant decrease in the phosphorylation of tyrosine 1009 on the PDGF beta receptor as well as the src homology 2 phosphatase-2 (SHP-2) and the tyrosine kinase Src, two enzymes which are positive mediators of PDGF-induced migration. Pre-treatment with Ang-(1-7) attenuated the PDGF-dependent increase in the phosphoY1009-PDGF receptor by 60%, phosphoY580-SHP-2 by 56% and phosphoY416-Src by 45% (n=5, p<0.05). These data demonstrate that Ang-(1-7) inhibits VSMC migration to attenuate neointimal formation, which may result from a reduction in the phosphorylation of the PDGF receptor or attenuation of the cellular events resulting from receptor activation. Further, these results suggest that Ang-(1-7) may be administered as a targeted therapeutic to prevent vascular restenosis.

Abstract 530: Vascular Remodeling by Angiotensin Peptide Hormones Alters Reactivity of the Microcirculation

Endothelial dysfunction associated with hypertension leads to end-organ damage through impairment in tissue perfusion. Angiotensin II (Ang II) causes vascular remodeling and fibrotic stiffening and attenuates endothelial-dependent vasorelaxation. However, the heptapeptide hormone angiotensin-(1-7) [Ang-(1-7)] reduces the structural effects of Ang II and acutely vasodilates vessels ex vivo . Lewis rats were chronically treated with either Ang II, Ang-(1-7), or both angiotensin peptides to examine the effect of the peptide hormones on microvascular remodeling and reactivity of cremaster muscle arterioles in vivo . Cremaster arterioles (50 microns in diameter) were visualized by intravital microscopy to measure vascular reactivity. Ang II elevated systolic blood pressure by 43 mmHg, an effect that was not changed by co-administration of Ang-(1-7); Ang-(1-7) alone had no effect. Ang II increased the media to lumen ratio (by 82% compared to Sham, n=7, p<0.01) and perivascular fibrosis (by 133% compared to Sham, n=7, p<0.001), while co-treatment with Ang-(1-7) attenuated the Ang II-enhanced remodeling and fibrosis to values no different than Sham or Ang-(1-7) alone. Phenylephrine (PE) elicited vasoconstriction in Sham rats, reducing vessel diameter by 21%, and this effect was not altered in rats treated with Ang II. Although PE-constricted arterioles from Sham rats vasodilated in response to acetylcholine (Ach, a 31.4% increase in diameter), vessels from Ang II-treated rats had a blunted response to Ach (a 9% increase). These results suggest that the Ang II-mediated microvascular remodeling altered microvascular vasodilation. In contrast, arterioles from rats treated with Ang-(1-7) or the combination of Ang-(1-7) and Ang II did not constrict in response to PE or endothelin. However, acute administration of the nitric oxide synthase inhibitor L-NAME to Ang-(1-7)-treated rats restored the vasoconstrictive response to PE, indicating that Ang-(1-7) increases endogenous nitric oxide to maximally dilate microvascular arterioles and prevent constriction. These results suggest Ang-(1-7) may serve as an effective adjuvant therapy to attenuate end-organ damage by increasing blood flow and tissue perfusion caused by hypertension.

Differences in oxidative stress status and expression of MKP-1 in dorsal medulla of transgenic rats with altered brain renin-angiotensin system

ANG II-stimulated production of reactive oxygen species (ROS) through NADPH oxidase is suggested to activate MAPK pathways, which are implicated in neurally mediated pressor effects of ANG II. Emerging evidence suggests that ANG-(1-7) up regulates MAPK phosphatases to reduce MAPK signaling and attenuate actions of ANG II. Whether angiotensin peptides participate in long-term regulation of these systems in the brain is not known. Therefore, we determined tissue and mitochondrial ROS, as well as expression and activity of MAPK phosphatase-1 (MKP-1) in brain dorsal medullary tissue of hypertensive transgenic (mRen2)27 rats exhibiting higher ANG II/ANG-(1-7) tone or hypotensive transgenic rats with targeted decreased glial expression of angiotensinogen, ASrAOGEN (AS) exhibiting lower ANG II/ANG-(1-7) tone compared with normotensive Sprague-Dawley (SD) rats that serve as the control strain. Transgenic (mRen2)27 rats showed higher medullary tissue NADPH oxidase activity and dihydroethidium fluorescence in isolated mitochondria vs. SD or AS rats. Mitochondrial uncoupling protein 2 was lower in AS and unchanged in (mRen2)27 compared with SD rats. MKP-1 mRNA and protein expression were higher in AS and unchanged in (mRen2)27 compared with SD rats. AS rats also had lower phosphorylated ERK1/2 and JNK consistent with higher MKP-1 activity. Thus, an altered brain renin-angiotensin system influences oxidative stress status and regulates MKP-1 expression. However, there is a dissociation between these effects and the hemodynamic profiles. Higher ROS was associated with hypertension in (mRen2)27 and normal MKP-1, whereas the higher MKP-1 was associated with hypotension in AS, where ROS was normal relative to SD rats.