Oxidative damage of cardiomyocytes is limited by extracellular regulated kinases 1/2-mediated induction of cyclooxygenase-2

Mechanisms of doxorubicin-induced cardiac inflammation and fibrosis; therapeutic targets and approaches

Doxorubicin plays a pivotal role in the treatment of various malignancies. Despite its efficacy, the cardiotoxicity associated with doxorubicin limits its clinical utility. The cardiotoxic nature of doxorubicin is attributed to several mechanisms, including its interference with mitochondrial function, the generation of reactive oxygen species (ROS), and the subsequent damage to cardiomyocyte DNA, proteins, and lipids. Furthermore, doxorubicin disrupts the homeostasis of cardiac-specific transcription factors and signaling pathways, exacerbating cardiac dysfunction. Oxidative stress, cell death, and other severe changes, such as mitochondrial dysfunction, activation of pro-oxidant enzymes, the renin-angiotensin system (RAS), endoplasmic reticulum (ER) stress, and infiltration of immune cells in the heart after treatment with doxorubicin, may cause inflammatory and fibrotic responses. Fibrosis and inflammation can lead to a range of disorders in the heart, resulting in potential cardiac dysfunction and disease. Various adjuvants have shown potential in preclinical studies to mitigate these challenges associated with cardiac inflammation and fibrosis. Antioxidants, plant-based products, specific inhibitors, and cardioprotective drugs may be recommended to alleviate cardiotoxicity. This review explores the complex mechanisms of doxorubicin-induced heart inflammation and fibrosis, identifies possible cellular and molecular targets, and investigates potential substances that could help reduce these harmful effects.

Increased Myocardial MAO-A, Atrogin-1, and IL-1β Expression in Transgenic Mice with Pancreatic Carcinoma-Benefit of MAO-A Inhibition for Cardiac Cachexia

Cancer cachexia (CC) continues to challenge clinicians by massively impairing patients' prognosis, mobility, and quality of life through skeletal muscle wasting. CC also includes cardiac cachexia as characterized by atrophy, compromised metabolism, innervation and function of the myocardium through factors awaiting clarification for therapeutic targeting. Because monoamine oxidase-A (MAO-A) is a myocardial source of H2O2 and implicated in myofibrillar protein catabolism and heart failure, we presently studied myocardial MAO-A expression, inflammatory cells, and capillarization together with transcripts of pro-inflammatory, -angiogenic, -apoptotic, and -proteolytic signals (by qRT-PCR) in a 3x-transgenic (LSL-KrasG12D/+; LSL-TrP53R172H/+; Pdx1-Cre) mouse model of orthotopic pancreatic ductal adenoarcinoma (PDAC) compared to wild-type (WT) mice. Moreover, we evaluated the effect of MAO-A inhibition by application of harmine hydrochloride (HH, 8 weeks, i.p., no sham control) on PDAC-related myocardial alterations. Myocardial MAO-A protein content was significantly increased (1.69-fold) in PDAC compared to WT mice. PDAC was associated with an increased percentage of atrogin-1+ (p < 0.001), IL-1β+ (p < 0.01), COX2+ (p < 0.001), and CD68+ (p > 0.05) cells and enhanced transcripts of pro-inflammatory IL-1β (2.47-fold), COX2 (1.53-fold), TNF (1.87-fold), and SOCS3 (1.64-fold). Moreover, PDAC was associated with a reduction in capillary density (-17%, p < 0.05) and transcripts of KDR (0.46-fold) but not of VEGFA, Notch1, or Notch3. Importantly, HH treatment largely reversed the PDAC-related increases in atrogin-1+, IL-1β+, and TNF+ cell fraction as well as in COX2, IL-1β, TNF, and SOCS3 transcripts, whereas capillary density and KDR transcripts failed to improve. In mice with PDAC, increased myocardial pro-atrophic/-inflammatory signals are attributable to increased expression of MAO-A, because they are significantly improved with MAO-A inhibition as a potential novel therapeutic option. The PDAC-related loss in myocardial capillary density may be due to other mechanisms awaiting evaluation with consideration of cardiomyocyte size, cardiac function and physical activity.

Angiotensin-(1-7) Treatment Early in Life Prevents Cardiac Hypertrophy in Adult Hypertensive Rats

ABSTRACT

Angiotensin (Ang)-(1-7) is a cardioprotective peptide of the renin-angiotensin system. Prepuberty has been considered as a later susceptible window of development, and stressful factors in this life phase can induce chronic diseases in adulthood. We aimed to investigate whether the treatment with Ang-(1-7) during the prepuberty could attenuate the development of hypertension and cardiac injury in adult spontaneously hypertensive rats (SHRs). SHRs were treated with Ang-(1-7) (24 μg/kg/h) from age 4 to 7 weeks. Systolic blood pressure was measured by tail-cuff plethysmography up to 17th week. Thereafter, echocardiography was performed, and the rats were euthanized for the collection of tissues and blood. Ang-(1-7) did not change the systolic blood pressure but reduced the septal and posterior wall thickness, and cardiomyocyte hypertrophy and fibrosis in SHR. In addition, Ang-(1-7) reduced the gene expression of atrial natriuretic peptide and brain natriuretic peptide, increased the metalloproteinase 9 expression, and reduced the extracellular signal-regulated kinases 1/2 phosphorylation. Ang-(1-7) also prevented the reduction of Mas receptor but did not change the protein expression of angiotensin-converting enzyme, angiotensin-converting enzyme 2, AT1, and AT2. The treatment with Ang-(1-7) decreased the malondialdehyde (MDA) levels and increased superoxide dismutase-1 and catalase activities and protein expression of catalase. Our findings demonstrate that the treatment of SHR with Ang-(1-7) for 3 weeks early in life promotes beneficial effects in the heart later in life, even without altering blood pressure, through mechanisms involving the reduction of oxidative stress and ERK1/2 phosphorylation. In addition, this study supports the prepuberty as an important programming window.

Chlorogenic acid attenuates deoxynivalenol-induced apoptosis and pyroptosis in human keratinocytes via activating Nrf2/HO-1 and inhibiting MAPK/NF-κB/NLRP3 pathways

Deoxynivalenol (DON) is a common mycotoxic contaminant, frequently found in food and feed, causing a severe threat to human and animal health. Because of the widespread contamination of DON, humans involved in agricultural practices may be directly exposed to DON through the skin route. Chlorogenic acid (CGA) is a phenolic acid, which has anti-inflammatory and antioxidant properties. However, it is still unclear whether CGA can protect against DON-induced skin damage. Here, the effect of CGA on mitigating damage to human keratinocytes (HaCaT) triggered by DON, as well as its underlying mechanisms were investigated. Results demonstrated that DON exposure significantly decreased cell viability, and induced excessive mitochondrial reactive oxygen species (mtROS) generation, mitochondrial damage, oxidative stress, cell apoptosis and pyroptosis. However, CGA pretreatment for 2 h significantly increased cell viability and reversed DON-induced oxidative stress by improving antioxidant enzyme activities such as superoxide dismutase (SOD), glutathione (GSH), catalase (CAT), reducing mtROS generation and enhancing mitochondrial function through activating Nrf2/HO-1 pathway. Moreover, CGA significantly increased the Bcl-2 protein expression, decreased the protein expressions of Bax and cleaved Caspase-3, and suppressed the phosphorylated of ERK, JNK, NF-κB. Further experiments revealed that CGA could also inhibit the pyroptosis-related protein expressions including NLRP3, cleaved Caspase-1, GSDMD-N, cleaved IL-1β and IL-18. In conclusion, our results suggest that CGA could attenuate DON-induced oxidative stress, inflammation, and apoptosis by activating the Nrf2/HO-1 pathway and inhibiting MAPK/NF-κB/NLRP3 pathway. CGA might be a novel promising therapeutic agent for alleviating the dermal damage triggered by DON.

Role of adipocytokines in endometrial cancer progression

Endometrial cancer is considered a significant barrier to increasing life expectancy and remains one of the most common malignant cancers among women in many countries worldwide. The increasing mortality rates are potentially proportional to the increasing obesity incidence. Adipose tissue secretes numerous adipocytokines, which may play important roles in endometrial cancer progression. In this scenario, we describe the role of adipocytokines in cell proliferation, cell invasion, cell adhesion, inflammation, angiogenesis, and anti-apoptotic action. A better understanding of the mechanisms of these adipocytokines may open up new therapeutic avenues for women with endometrial cancer. In the future, larger prospective studies focusing on adipocytokines and specific inhibitors should be directed at preventing the rapidly increasing prevalence of gynecological malignancies.

LncRNA MALAT1 functions as a biomarker of no-reflow phenomenon in ST-segment elevation myocardial infarction patients receiving primary percutaneous coronary intervention

MALAT1 was reported to sponge miR-30e, miR-126 and miR-155 in the pathogenesis of many diseases. Plasma miR-30e can indicate the risk of no-reflow during primary percutaneous coronary intervention (pPCI), while miR-126 can be used as a predictor of coronary slow flow phenomenon. In this study, we compared the diagnostic value of above genes in the prediction of no-reflow phenomenon in ST-segment elevation myocardial infarction (STEMI) subjects receiving pPCI. Quantitative real-time PCR, ELISA, Western blot and luciferase assays were performed to explore the regulatory relationship of MALAT1/miR-30e, MALAT1/miR-126, MALAT1/miR-155, miR-126/HPSE, and miR-155/EDN1. ROC analysis was carried out to evaluate the potential value of MALAT1, miRNAs and target genes in differentiating normal reflow and no-reflow in STEMI patients receiving pPCI. Elevated MALAT1, CRP, HPSE, and EDN1 expression and suppressed miR-30e, miR-155 and miR-126 expression was found in the plasma of STEMI patients receiving pPCI who were diagnosed with no-reflow phenomenon. ROC analysis showed that the expression of MALAT1, miR-30e, miR-126 and CRP could be used as predictive biomarkers to differentiate normal reflow and no-reflow in STEMI patients receiving pPCI. MALAT1 was found to suppress the expression of miR-30e, miR-126 and miR-155, and HPSE and EDN1 were respectively targeted by miR-126 and miR-155. This study demonstrated that MALAT1 could respectively sponge the expression of miR-30e, miR-126 and miR-155. And miR-30e, miR-126 and miR-155 respectively targeted CRP, HPSE and EDN1 negatively. Moreover, MALAT1 could function as an effective biomarker of no-reflow phenomenon in STEMI patients receiving pPCI.

New horizons in the roles and associations of COX-2 and novel natural inhibitors in cardiovascular diseases

Age-related cardiovascular disease is the leading cause of death in elderly populations. Coxibs, including celecoxib, valdecoxib, etoricoxib, parecoxib, lumiracoxib, and rofecoxib, are selective cyclooxygenase-2 (COX-2) inhibitors used to treat osteoarthritis and rheumatoid arthritis. However, many coxibs have been discontinued due to adverse cardiovascular events. COX-2 contains cyclooxygenase (COX) and peroxidase (POX) sites. COX-2 inhibitors block COX activity without affecting POX activity. Recently, quercetin-like flavonoid compounds with OH groups in their B-rings have been found to serve as activators of COX-2 by binding the POX site. Galangin-like flavonol compounds serve as inhibitors of COX-2. Interestingly, nabumetone, flurbiprofen axetil, piketoprofen-amide, and nepafenac are ester prodrugs that inhibit COX-2. The combination of galangin-like flavonol compounds with these prodrug metabolites may lead to the development of novel COX-2 inhibitors. This review focuses on the most compelling evidence regarding the role and mechanism of COX-2 in cardiovascular diseases and demonstrates that quercetin-like compounds exert potential cardioprotective effects by serving as cofactors of COX-2.

New insights into molecular mechanisms of "Cold or Hot" nature of food: When East meets West

Traditional Chinese medicines are largely adopted in China and have a key importance in the world medical system. Cold-hot nature is the important characteristics of food and Chinese Materia Medica in the traditional Chinese medicine, relating to food functions in the organism. As compared to the studies on the cold and hot nature in Chinese medicine, the research studies carried out to establish the association between cold-hot nature and food are insufficient. Intending to investigate the criteria to discriminate the cold-hot nature of food and Chinese medicine scientifically, this review collected the cold-hot nature-related literature in recent 20 years in several popular databases such as PubMed, Google Scholar, and Science Direct. This review explored that the cold and hot natures are not only linked to the chemical components such as water, carbohydrates, lipids, and amino acids, but also correlated to the biological effects, comprising of energy metabolism, inflammation response, oxidation reaction, immune response, and cell growth and proliferation. Besides, this review further put forward the possibility that cold-hot nature of food and Chinese medicine exert different biological effects on the inflammatory response via regulating the signaling pathways viz. NF-κB and MAPK. More extensive studies are needed to consider the overall connections between both the biological effects and chemical components and how food processing affects the cold-hot nature of the food.

Nidogen-1 Mitigates Ischemia and Promotes Tissue Survival and Regeneration

Ischemia impacts multiple organ systems and is the major cause of morbidity and mortality in the developed world. Ischemia disrupts tissue homeostasis, driving cell death, and damages tissue structure integrity. Strategies to heal organs, like the infarcted heart, or to replace cells, as done in pancreatic islet β-cell transplantations, are often hindered by ischemic conditions. Here, it is discovered that the basement membrane glycoprotein nidogen-1 attenuates the apoptotic effect of hypoxia in cardiomyocytes and pancreatic β-cells via the αvβ3 integrin and beneficially modulates immune responses in vitro. It is shown that nidogen-1 significantly increases heart function and angiogenesis, while reducing fibrosis, in a mouse postmyocardial infarction model. These results demonstrate the protective and regenerative potential of nidogen-1 in ischemic conditions.

Mesoporous Polydopamine Nanoparticles Attenuate Morphine Tolerance in Neuropathic Pain Rats by Inhibition of Oxidative Stress and Restoration of the Endogenous Antioxidant System

Oxidative stress resulting from reactive oxygen species (ROS) is known to play a key role in numerous neurological disorders, including neuropathic pain. Morphine is one of the commonly used opioids for pain management. However, long-term administration of morphine results in morphine antinociceptive tolerance (MAT) through elevation of ROS and suppression of natural antioxidant defense mechanisms. Recently, mesoporous polydopamine (MPDA) nanoparticles (NPS) have been known to possess strong antioxidant properties. We speculated that morphine delivery through an antioxidant nanocarrier might be a reasonable strategy to alleviate MAT. MPDAs showed a high drug loading efficiency of ∼50%, which was much higher than conventional NPS. Spectral and in vitro studies suggest a superior ROS scavenging ability of NPS. Results from a rat neuropathic pain model demonstrate that MPDA-loaded morphine (MPDA@Mor) is efficient in minimizing MAT with prolonged analgesic effect and suppression of pro-inflammatory cytokines. Additionally, serum levels of liver enzymes and levels of endogenous antioxidants were measured in the liver. Treatment with free morphine resulted in elevated levels of liver enzymes and significantly lowered the activities of endogenous antioxidant enzymes in comparison with the control and MPDA@Mor-treated group. Histopathological examination of the liver revealed that MPDA@Mor can significantly reduce the hepatotoxic effects of morphine. Taken together, our current work will provide an important insight into the development of safe and effective nano-antioxidant platforms for neuropathic pain management.

Mechanisms of the Cardiac Myocyte-Damaging Effects of Dasatinib

The anticancer drug dasatinib (Sprycel) is a BCR-ABL1-targeted tyrosine kinase inhibitor used in treating chronic myelogenous leukemia that has been shown in clinical trials to display cardiovascular toxicities. While dasatinib potently inhibits BCR-ABL1, it is not a highly selective kinase inhibitor and may have off-target effects. A neonatal rat cardiac myocyte model was used to investigate potential mechanisms by which dasatinib damaged myocytes. The anthracycline cardioprotective drug dexrazoxane was shown to be ineffective in preventing dasatinib-induced myocyte damage. Dasatinib treatment increased doxorubicin accumulation in myocytes and doxorubicin-induced myocyte damage, likely through its ability to bind to one or more ABC-type efflux transporters. Dasatinib induced myocyte damage either after a brief treatment that mimicked the clinical situation, or more potently after continuous treatment. Dasatinib slightly induced apoptosis in myocytes as evidenced by increases in caspase-3/7 activity. Dasatinib treatment reduced pERK levels in myocytes most likely through inhibition of RAF, which dasatinib strongly inhibits. Thus, inhibition of the RAF/MEK/ERK pro-survival pathway in the heart may be, in part, a mechanism by which dasatinib induces cardiovascular toxicity.

Effect of p53 activation on experimental right ventricular hypertrophy

The leading cause of death in Pulmonary Arterial Hypertension (PAH) is right ventricular (RV) failure. The tumor suppressor p53 has been associated with left ventricular hypertrophy (LVH) and remodeling but its role in RV hypertrophy (RVH) is unclear. The purpose of this study was to determine whether pharmacological activation of p53 by Quinacrine affects RV remodeling and function in the pulmonary artery banding (PAB) model of compensated RVH in mice. The effects of p53 activation on cellular functions were studied in isolated cardiomyocytes, cardiac fibroblasts and endothelial cells (ECs). The expression of p53 was examined both on human RV tissues from patients with compensated and decompensated RVH and in mouse RV tissues early and late after the PAB. As compared to control human RVs, there was no change in p53 expression in compensated RVH, while a marked upregulation was found in decompensated RVH. Similarly, in comparison to SHAM-operated mice, unaltered RV p53 expression 7 days after PAB, was markedly induced 21 days after the PAB. Quinacrine induced p53 accumulation did not further deteriorate RV function at day 7 after PAB. Quinacrine administration did not increase EC death, neither diminished EC number and capillary density in RV tissues. No major impact on the expression of markers of sarcomere organization, fatty acid and mitochondrial metabolism and respiration was noted in Quinacrine-treated PAB mice. p53 accumulation modulated the expression of Heme Oxygenase 1 (HO-1) and Glucose Transporter (Glut1) in mouse RVs and in adult cardiomyocytes. We conclude that early p53 activation in PAB-induced RVH does not cause substantial detrimental effects on right ventricular remodeling and function.

Zinc protects against cadmium-induced toxicity in neonatal murine engineered cardiac tissues via metallothionein-dependent and independent mechanisms

Cadmium (Cd) is a nonessential heavy metal and a prevalent environmental toxin that has been shown to induce significant cardiomyocyte apoptosis in neonatal murine engineered cardiac tissues (ECTs). In contrast, zinc (Zn) is a potent metallothionein (MT) inducer, which plays an important role in protection against Cd toxicity. In this study, we investigated the protective effects of Zn against Cd toxicity in ECTs and explore the underlying mechanisms. ECTs were constructed from neonatal ventricular cells of wild-type (WT) mice and mice with global MT gene deletion (MT-KO). In WT-ECTs, Cd (5-20 μM) caused a dose-dependent toxicity that was detected within 8 h evidenced by suppressed beating, apoptosis, and LDH release; Zn (50-200 μM) dose-dependently induced MT expression in ECTs without causing ECT toxicity; co-treatment of ECT with Zn (50 µM) prevented Cd-induced toxicity. In MT-KO ECTs, Cd toxicity was enhanced; but unexpectedly, cotreatment with Zn provided partial protection against Cd toxicity. Furthermore, Cd, but not Zn, significantly activated Nrf2 and its downstream targets, including HO-1; inhibition of HO-1 by a specific HO-1 inhibitor, ZnPP (10 µM), significantly increased Cd-induced toxicity, but did not inhibit Zn protection against Cd injury, suggesting that Nrf2-mediated HO-1 activation was not required for Zn protective effect. Finally, the ability of Zn to reduce Cd uptake provided an additional MT-independent mechanism for reducing Cd toxicity. Thus, Zn exerts protective effects against Cd toxicity for murine ECTs that are partially MT-mediated. Further studies are required to translate these findings towards clinical trials.

Manganese Oxide Nanozymes Ameliorate Mechanical Allodynia in a Rat Model of Partial Sciatic Nerve-Transection Induced Neuropathic Pain

BACKGROUND

Reactive oxygen species (ROS) induced oxidative stress is linked to numerous neurological diseases, including neuropathic pain. Natural ROS scavenging enzymes like superoxide dismutase (SOD) and catalase have been found to be efficient in alleviating neuropathic pain. However, their sensitivity towards extreme pH and a short half-life limit their efficacy in vivo. Manganese oxide nanoparticles (MONPs) are recently known to possess ROS scavenging properties. In this study, MONPs were examined for their therapeutic effect on neuropathic pain.

METHODS

The MONPs were synthesized by a hydrothermal method. The synthesized MONPs were characterized by UV/Vis, TEM, SEM, FTIR, NTA and XRD. The biocompatibility of the nanoparticles is evaluated in neural cells using LDH assay. MONPs were evaluated for their antioxidant activity by DPPH assay. In addition, in vitro ROS scavenging properties were examined in bone marrow-derived macrophage (BMDM) cells using 2',7'-dichlorofluorescin diacetate (DCFDA) assay. To evaluate the in vivo efficacy of nanoparticles, neuropathic pain was induced in Wistar rats by partial sciatic nerve transection (PSNT). On post-transection days 14 to 18, rats were intrathecally injected with MONPs and paw withdrawal threshold was measured. The spinal cords were collected and processed for Western blotting and histological analysis.

RESULTS

The synthesized MONPs were biocompatible and showed effective antioxidant activity against DPPH free radical scavenging. Further, the nanoparticles scavenged ROS efficiently in vitro in BMDM and their intrathecal administration significantly reduced mechanical allodynia as well as the expression of cyclooxygenase-2 (COX-2), an important mediator of chronic and inflammatory pain in the spinal dorsal horns of PSNT rats.

CONCLUSION

As ROS play a significant role in neuropathic pain, we expect that MONPs could be a promising tool for the treatment of various inflammatory diseases and might also serve as a potential nanocarrier for the delivery of analgesics.

Doxorubicin-associated takotsubo cardiomyopathy in a patient with adult T-cell leukemia/lymphoma

This case highlights the first reported association of doxorubicin with takotsubo cardiomyopathy (TC) presenting as cardiogenic shock during the first continuous infusion in a patient with adult T-cell leukemia/lymphoma. We aim to raise awareness to recognize and distinguish between irreversible doxorubicin-associated cardiomyopathy and reversible doxorubicin-associated TC in patients with cancer.

Neonatal murine engineered cardiac tissue toxicology model: Impact of dexrazoxane on doxorubicin induced injury

Doxorubicin (DOX) induced cardiotoxicity is a life-threatening side effect of chemotherapy and decreased cardiac function can present years after treatment. Despite the investigation of a broad range of pharmacologic interventions, to date the only drug shown to reduce DOX-related cardiotoxicity in preclinical studies and limited clinical trials is the iron chelating agent, dexrazoxane (DRZ), although the mechanisms responsible for DRZ mediated protection from DOX related cardiotoxicity remain unclear. Engineered cardiac tissues (ECTs) can be used for tissue repair strategies and as in vitro surrogate models to test cardiac toxicities and preventative countermeasures. Neonatal murine ECTs display cardiotoxicity in response to the environmental toxin, cadmium, and reduced cadmium toxicity with Zinc co-treatment, in part via the induction of the anti-oxidant Metallothionein (MT). We adapted our in vitro ECT model to determine the feasibility of using the ECT approach to investigate DOX-related cardiac injury and DRZ prevention. We found: (1) DOX induced dose and time dependent cell death in ECTs; (2) Zinc did not show protection from DOX cardiotoxicity; (3) MT overexpression induced by Zinc, low dose Cd pretreatment, or MT-overexpression (MT-TG) did not reduce ECT DOX cardiotoxicity; (4) DRZ reduced ECT DOX induced cell death; and (5) The mechanism of DRZ ECT protection from DOX cardiotoxicity was topoisomerase 2B (TOP2B) inhibition rather than reduced reactive oxygen species. Our data support the feasibility of ECTs as an in vitro platform technology for the investigation of drug induced cardiotoxicities including the role of TOP2B in DOX toxicity and DRZ mediated DOX toxicity prevention.

Association of COX2 -765G>C promoter polymorphism and coronary artery disease in Korean population

BACKGROUND

Cyclooxygenase-2 (COX2) plays a role in the formation of prostaglandins, which contribute to the inflammation involved in atherosclerosis. However, the role of the COX2 -765G>C polymorphism in susceptibility to coronary artery disease (CAD) is controversial.

OBJECTIVE

To identify the association between COX2 -765G>C polymorphism with CAD risk in Korean patients. We recruited 622 patients who were diagnosed to have coronary artery disease and 202 controls who did not have history and vascular disease risk factors.

METHODS

Using polymerase chain reaction-restriction fragment length polymorphism, the COX2 -765G>C polymorphism was analyzed in 622 Korean patients who received percutaneous coronary intervention and in 202 healthy control subjects.

RESULTS

The GC+CC genotype frequencies of the -765G>C polymorphism were significantly different between the CAD and control groups. The COX2 -765G>C polymorphism showed peculiar associations with CAD according to the presence of hyperlipidemia and plasma folate levels. However, there were no associations between the -765G>C polymorphism and the rates of hypertension, diabetes mellitus, or homocysteine levels.

CONCLUSION

This study suggests that the COX2 -765G>C polymorphism is a possible genetic determinant for the risk of CAD, and an individual risk factor in Koreans. Thus, further association studies between the COX2 polymorphism and atherosclerotic-related diseases such as cerebrovascular or cardiovascular diseases in other races or ethnicities will be needed.

Risk of cardiotoxicity induced by adjuvant anthracycline-based chemotherapy and radiotherapy in young and old Asian women with breast cancer

PURPOSE

The risk of cardiotoxicity induced by adjuvant anthracycline-based chemotherapy (CT) and radiotherapy (RT) is yet to be investigated in a large-scale randomized controlled trial with an adequate sample size of young and old women with breast cancer.

PATIENTS AND METHODS

To compare the occurrence of major heart events (heart failure and coronary artery disease) in patients with breast cancer, 3489 women who underwent surgical resection of the breast tumor were retrospectively selected from the Taiwan National Health Insurance Research Database. The patients were categorized into the following groups based on their treatment modalities: group 1 (n = 1113), no treatment; group 2 (n = 646), adjuvant RT alone; group 3 (n = 705), adjuvant anthracycline-based CT alone; and group 4 (n = 1025), combined adjuvant RT and anthracycline-based CT.

RESULTS

The mean patient age was 50.35 years. Subsequent coronary artery disease and heart failure were identified in 244 (7.0%) and 206 (5.9%) patients, respectively. All three adjuvant therapies were significant independent prognostic factors of major heart events (adjusted hazard ratio [95% confidence interval]: 1.47 [1.24-1.73]; 1.48 [1.25-1.75], and 1.92 [1.65-2.23] in groups 2, 3, and 4, respectively). In patients aged ≥50 years with breast cancer who underwent surgery, the log-rank p values of groups 2 and 3 after adjustment were 0.537 and 0.001, respectively.

CONCLUSION

Adjuvant RT can increase cardiotoxicity in patients with breast cancer, particularly when used in combination with anthracycline-based CT. Therefore, it should be offered with optimal heart-sparing techniques, particularly in younger patients with good prognosis and long life expectancy.

Diethyl Blechnic, a Novel Natural Product Isolated from Salvia miltiorrhiza Bunge, Inhibits Doxorubicin-Induced Apoptosis by Inhibiting ROS and Activating JNK1/2

Doxorubicin (DOX) is a widely used antineoplastic agent in clinics. However, its clinical application is largely limited by its cardiotoxicity. Diethyl blechnic (DB) is a novel compound isolated from Salvia miltiorrhiza Bunge. Here, we study the effect of DB on DOX-induced cardiotoxicity and its underlying mechanisms. Cellular viability was tested by 3-[-4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) and protein level was evaluated by Western blotting. 5,5’,6,6’-tetrachloro-1,1’,3,3’-tetraethylbenzimidazolylcarbocyanine iodide (JC-1) staining was performed to determine the mitochondrial membrane potential (MMP). Hoechst 33342 staining and TUNEL staining was performed to test the apoptosis. Reactive oxygen species (ROS) generation was investigated by using flow cytometry. DB significantly inhibited DOX-induced apoptosis in H9c2 cells and primary cultured cardiomyocytes. Moreover, DB decreased cell apoptotic morphological changes and reversed the mitochondrial membrane potential induced by DOX. Meanwhile, pre-treatment with DB increased the expression levels of B-cell lymphoma 2 (Bcl-2), B-cell lymphoma-extra-large (Bcl-xl), and survivin and reduced the expression levels of Bcl-2-associated X protein (Bax), p-p53, cytochrome c (cyt c), and cleaved-caspase 3, 7, 8, 9 in the protein levels in DOX-treated H9c2 cells. Furthermore, DB suppressed ROS generation. The DB-mediated protective effects were accompanied by increased c-Jun N-terminal kinase1/2 (JNK1/2) expression. In addition, SP600125, the inhibitor of JNK1/2, abolished the protective effect of DB. We concluded that DB protected cardiomyocytes against DOX-induced cytotoxicity by inhibiting ROS and activating the JNK1/2 pathway. Therefore, DB is a promising candidate as a cardioprotective agent against DOX-induced cardiotoxicity.

The Myocyte-Damaging Effects of the BCR-ABL1-Targeted Tyrosine Kinase Inhibitors Increase with Potency and Decrease with Specificity

Five clinically approved BCR-ABL1-targeted tyrosine kinase inhibitors (bosutinib, dasatinib, imatinib, nilotinib, and ponatinib) used for treating chronic myelogenous leukemia have been studied in a neonatal rat myocyte model for their relative ability to induce myocyte damage. This was done in order to determine if kinase inhibitor-induced myocyte damage was a consequence of inhibiting ABL1 (on-target effects), or due to a lack of kinase selectivity (off-target effects) since previous studies have come up with conflicting conclusions about whether imatinib-induced cardiotoxicity results directly from inhibition of ABL1. The most specific and least potent inhibitors, imatinib and nilotinib, induced the least myocyte damage, while the least specific and most potent inhibitors, ponatinib and dasatinib, induced the most damage. Inhibitor-induced myocyte damage also correlated with clinically observed cardiovascular toxicity. Growth inhibition of the erythroleukemic K562 human cell line with a constitutively active BCR-ABL1 kinase was negatively correlated with inhibitor-induced myocyte damage, which suggests that inhibition of ABL1 causes myocyte damage. Myocyte damage was also negatively correlated with inhibitor dissociation binding constants and with inhibition of enzymatic ABL1 kinase activity. Myocyte damage was also positively correlated with two measures of inhibitor selectivity, which suggests that a lack of inhibitor selectivity is responsible for myocyte damage. In conclusion, myocyte damage, and thus the cardiovascular toxicity of the BCR-ABL1-targeted tyrosine kinase inhibitors, is due to direct inhibition of ABL1 and/or their lack of inhibitor selectivity.

Protective effects of curcumin against doxorubicin-induced toxicity and resistance: A review

Doxorubicin (DOX)-induced toxicity and resistance are major obstacles in chemotherapeutic approaches. Despite effective in the treatment of numerous malignancies, some clinicians have voiced concern that DOX has the potential to cause debilitating consequences in organ tissues, especially the heart. The mechanisms of toxicity and resistance are respectively related to induction of reactive oxygen species (ROS) and up-regulation of ATP-binding cassette (ABC) transporter. Curcumin (CUR) with several biological and pharmacological properties is expected to restore DOX-mediated impairments to tissues. This review is intended to address the current knowledge on DOX adverse effects and CUR protective actions in the heart, kidneys, liver, brain, and reproductive organs. Coadministration of CUR and DOX is capable of ameliorating DOX toxicity pertained to antioxidant, apoptosis, autophagy, and mitochondrial permeability.

Targeting nano drug delivery to cancer cells using tunable, multi-layer, silver-decorated gold nanorods

Multifunctional nanoparticles have high potential as targeting delivery vehicles for cancer chemotherapy. In this study, silver-decorated gold nanorods (AuNR\Ag) have been successfully used to deliver specific, targeted chemotherapy against breast cancer (MCF7) and prostate carcinoma (PC3) cell lines. Doxorubicin, a commonly used chemotherapy, and anti-Epithelial cell adhesion molecule (anti-EpCAM) antibodies were covalently bonded to thiolated polyethylene glycol-coated AuNR\Ag, and the resultant system was used to deliver the drugs to cancer cells in vitro. Furthermore, these nanoparticles have a unique spectral signature by surface enhanced Raman spectroscopy (SERS), which enables reliable detection and monitoring of the distribution of these chemotherapy constructs inside cells. The development of interest in a plasmonic nano drugs system with unique spectroscopic signatures could result in a clinical approach to the precise targeting and visualization of cells and solid tumors while delivering molecules for the enhanced treatment of cancerous tumors.

Hsp90 inhibitor geldanamycin attenuates the cytotoxicity of sunitinib in cardiomyocytes via inhibition of the autophagy pathway

Sunitinib malate (sunitinib) is an orally available, multitargeted tyrosine kinase inhibitor with antitumor and antiangiogenic activities. Although sunitinib is effective for the treatment of patients with gastrointestinal stromal tumor, advanced renal cell carcinoma, or pancreatic neuroendocrine tumor, adverse cardiac events associated with sunitinib administration have been reported. Here, we examined the effect of geldanamycin, an inhibitor of heat shock protein (Hsp) 90, on sunitinib-induced cytotoxicity in cardiomyocytes. First, we found that treatment with geldanamycin or other Hsp90 inhibitors (tanespimycin, ganetespib, or BIIB021) significantly attenuated sunitinib-induced cytotoxicity in rat H9c2 cardiomyocytes, suggesting a drug-class effect of Hsp90 inhibitors. We then examined the mechanisms underlying sunitinib-induced cytotoxicity and found that sunitinib induced autophagy in H9c2 cells and that pretreatment with geldanamycin inhibited the induction of autophagy by promoting degradation of the autophagy-related proteins Atg7, Beclin-1, and ULK1. Pharmacological assessment with autophagy inhibitors confirmed that geldanamycin attenuated the cytotoxicity of sunitinib by interfering with autophagy. In addition, we found that the molecular chaperone Hsp70, which is induced by geldanamycin, was not involved in the attenuation of sunitinib-induced cytotoxicity. Finally, to provide more clinically relevant data, we confirmed that geldanamycin attenuated sunitinib-induced cytotoxicity in human induced pluripotent stem cell-derived cardiomyocytes. Together, these data suggest that geldanamycin attenuates sunitinib-induced cytotoxicity in cardiomyocytes by inhibiting the autophagy pathway. Thus, the further investigation of combination or sequential treatment with an Hsp90 inhibitor and sunitinib is warranted as a potential strategy of attenuating the cardiotoxicity associated with sunitinib administration in the clinical setting.

Chlorogenic acid analogues from Gynura nepalensis protect H9c2 cardiomyoblasts against H2O2-induced apoptosis

AIM

Chlorogenic acid has shown protective effect on cardiomyocytes against oxidative stress-induced damage. Herein, we evaluated nine caffeoylquinic acid analogues (1-9) isolated from the leaves of Gynura nepalensis for their protective effect against H₂O₂-induced H9c2 cardiomyoblast damage and explored the underlying mechanisms.

METHODS

H9c2 cardiomyoblasts were exposed to H₂O₂ (0.3 mmol/L) for 3 h, and cell viability was detected with MTT assay. Hoechst 33342 staining was performed to evaluate cell apoptosis. MMPs (mitochondrial membrane potentials) were measured using a JC-1 assay kit, and ROS (reactive oxygen species) generation was measured using CM-H₂ DCFDA. The expression levels of relevant proteins were detected using Western blot analysis.

RESULTS

Exposure to H₂O₂ markedly decreased the viability of H9c2 cells and catalase activity, and increased LDH release and intracellular ROS production; accompanied by a loss of MMP and increased apoptotic rate. Among the 9 chlorogenic acid analogues as well as the positive control drug epigallocatechin gallate (EGCG) tested, compound 6 (3,5-dicaffeoylquinic acid ethyl ester) was the most effective in protecting H9c2 cells from H₂O₂-induced cell death. Pretreatment with compound 6 (1.56-100 μmol/L) dose-dependently alleviated all the H₂O₂-induced detrimental effects. Moreover, exposure to H₂O₂ significantly increased the levels of Bax, p53, cleaved caspase-8, and cleaved caspase-9, and decreased the level of Bcl-2, resulting in cell apoptosis. Exposure to H₂O₂ also significantly increased the phosphorylation of p38, JNK and ERK in the H9c2 cells. Pretreatment with compound 6 (12.5 and 25 μmol/L) dose-dependently inhibited the H₂O₂-induced increase in the level of cleaved caspase-9 but not of cleaved caspase-8. It also dose-dependently suppressed the H₂O₂-induced phosphorylation of JNK and ERK but not that of p38.

CONCLUSION

Compound 6 isolated from the leaves of Gynura nepalensis potently protects H9c2 cardiomyoblasts against H₂O₂-induced apoptosis, possibly by inhibiting intrinsic apoptosis and the ERK/JNK pathway.

Anthracycline-Induced Cardiomyopathy in Adults

Anthracyclines are one of the most commonly used antineoplastic agent classes, and a core part of the treatment in breast cancers, hematological malignancies, and sarcomas. Their benefit is decreased by their well-recognized cardiotoxicity. The purpose of this review is to outline the presentation, mechanisms, diagnosis, and treatment of anthracyclines-induced cardiotoxicity. Symptomatic heart failure occurs in 2% to 5% of patients treated with anthrayclines and may be higher in older patients or patients with cardiovascular risk factors. The mechanisms involved in anthracycline-induced cardiotoxicity involve myocyte loss by apoptosis in the presence of a limited regenerative capacity. Once symptomatic, anthracycline-induced cardiotoxicity is associated with markedly decreased survival. Left ventricular ejection fraction (LVEF), mostly determined using echocardiography, is used to monitor patients treated with anthracyclines. As more than 1/3 of patients treated with anthracyclines do not recover their baseline LVEF once it is decreased, more sensitive echocardiographic indices of LV function such as myocardial deformation or biomarkers have been studied in patients monitoring. Cardioprotective treatments such as angiotensin-converting enzyme inhibitors, beta-blockers, iron chelators, statins, and metformin are also the topic of research efforts.

Involvement of BDNF/ERK signaling in spontaneous recovery from trimethyltin-induced hippocampal neurotoxicity in mice

Trimethyltin (TMT) toxicity causes histopathological damage in the hippocampus and induces seizure behaviors in mice. The lesions and symptoms recover spontaneously over time; however, little is known about the precise mechanisms underlying this recovery from TMT toxicity. We investigated changes in the brain-derived neurotrophic factor/extracellular signal-regulated kinases (BDNF/ERK) signaling pathways in the mouse hippocampus following TMT toxicity. Mice (7 weeks old, C57BL/6) administered TMT (2.6 mg/kg intraperitoneally) showed acute and severe neurodegeneration with increased TUNEL-positive cells in the dentate gyrus (DG) of the hippocampus. The mRNA and protein levels of BDNF in the hippocampus were elevated by TMT treatment. Immunohistochemical analysis showed that TMT treatment markedly increased phosphorylated ERK1/2 expression in the mouse hippocampus 1-4 days after TMT treatment, although the intensity of ERK immunoreactivity in mossy fiber decreased at 1-8 days post-treatment. In addition, ERK-immunopositive cells were localized predominantly in doublecortin-positive immature progenitor neurons in the DG. In primary cultured immature hippocampal neurons (4 days in vitro), BDNF treatment alleviated TMT-induced neurotoxicity, via activation of the ERK signaling pathway. Thus, we suggest that BDNF/ERK signaling pathways may be associated with cell differentiation and survival of immature progenitor neurons, and will eventually lead to spontaneous recovery in TMT-induced hippocampal neurodegeneration.

All-trans retinoic acid protects against doxorubicin-induced cardiotoxicity by activating the ERK2 signalling pathway

BACKGROUND AND PURPOSE

Doxorubicin is a powerful antineoplastic agent for treating a wide range of cancers. However, doxorubicin cardiotoxicity of the heart has largely limited its clinical use. All-trans retinoic acid (ATRA) plays an important role in many cardiac biological processes, but its protective effects on doxorubicin-induced cardiotoxicity remain unknown. Here, we studied the effect of ATRA on doxorubicin cardiotoxicity and the underlying mechanisms.

EXPERIMENTAL APPROACHES

Cellular viability assays, Western blotting and mitochondrial respiration analyses were employed to evaluate the cellular response to ATRA in H9c2 cells and primary cardiomyocytes. Quantitative PCR and gene knockdown were performed to investigate the underlying molecular mechanisms of ATRA's effects on doxorubicin cardiotoxicity.

KEY RESULTS

ATRA significantly inhibited doxorubicin-induced apoptosis in H9c2 cells and primary cardiomyocytes. ATRA was more effective against doxorubicin cardiotoxicity than resveratrol and dexrazoxane. ATRA also suppressed reactive oxygen species generation and restored expression levels of mRNA and proteins in the phase II detoxifying enzyme system: nuclear factor-E2-related factor 2, manganese superoxide dismutase, haem oxygenase-1, and mitochondrial function (mitochondrial membrane integrity, mitochondrial DNA copy numbers and mitochondrial respiration capacity, biogenesis and dynamics). Both a ERK1/2 inhibitor (U0126) and ERK2 siRNA, but not ERK1 siRNA, abolished the protective effect of ATRA against doxorubicin-induced toxicity in H9c2 cells. Remarkably, ATRA did not compromise the anticancer efficacy of doxorubicin in gastric carcinoma cells.

CONCLUSIONS AND IMPLICATIONS

ATRA protected cardiomyocytes against doxorubicin-induced toxicity, by activating the ERK2 pathway, without compromising its anticancer efficacy. Therefore, ATRA is a promising candidate as a cardioprotective agent against doxorubicin cardiotoxicity.

Mechanisms of Action and Reduced Cardiotoxicity of Pixantrone; a Topoisomerase II Targeting Agent with Cellular Selectivity for the Topoisomerase IIα Isoform

Pixantrone is a new noncardiotoxic aza-anthracenedione anticancer drug structurally related to anthracyclines and anthracenediones, such as doxorubicin and mitoxantrone. Pixantrone is approved in the European Union for the treatment of relapsed or refractory aggressive B cell non-Hodgkin lymphoma. This study was undertaken to investigate both the mechanism(s) of its anticancer activity and its relative lack of cardiotoxicity. Pixantrone targeted DNA topoisomerase IIα as evidenced by its ability to inhibit kinetoplast DNA decatenation; to produce linear double-strand DNA in a pBR322 DNA cleavage assay; to produce DNA double-strand breaks in a cellular phospho-histone γH2AX assay; to form covalent topoisomerase II-DNA complexes in a cellular immunodetection of complex of enzyme-to-DNA assay; and to display cross-resistance in etoposide-resistant K562 cells. Pixantrone produced semiquinone free radicals in an enzymatic reducing system, although not in a cellular system, most likely due to low cellular uptake. Pixantrone was 10- to 12-fold less damaging to neonatal rat myocytes than doxorubicin or mitoxantrone, as measured by lactate dehydrogenase release. Three factors potentially contribute to the reduced cardiotoxicity of pixantrone. First, its lack of binding to iron(III) makes it unable to induce iron-based oxidative stress. Second, its low cellular uptake may limit its ability to produce semiquinone free radicals and redox cycle. Finally, because the β isoform of topoisomerase II predominates in postmitotic cardiomyocytes, and pixantrone is demonstrated in this study to be selective for topoisomerase IIα in stabilizing enzyme-DNA covalent complexes, the attenuated cardiotoxicity of this agent may also be due to its selectivity for targeting topoisomerase IIα over topoisomerase IIβ.

Effect of inflammatory factor-induced cyclo-oxygenase expression on the development of reperfusion-related no-reflow phenomenon in acute myocardial infarction

No reflow after reperfusion therapy for myocardial infarction is a strong predictor of clinical outcome. Increased levels of inflammatory factors, including C-reactive protein (CRP), in patients with acute myocardial infarction (AMI) undergoing primary percutaneous coronary intervention (PCI) may affect myocardial perfusion. However, why the no-reflow phenomenon increases in inflammation stress after PCI is not clear. The aim of the present study was to determine the effects and molecular mechanisms underlying the effects of CRP on the expression of cyclo-oxygenase (COX) on the development of the no-reflow phenomenon. There was a significant increase in plasma levels of CRP and interleukin (IL)-6 in no-reflow patients, suggesting that inflammatory factors play an important role in the development of the no-reflow phenomenon. The mechanisms involved were further evaluated after reperfusion in a rat model mimicking the no-reflow phenomenon. Compared with normal reflow rats, there were significant increases in both COX-1 and COX-2 in cardiac tissue from no-reflow rats. The COX inhibitor indomethacin (5 mg/kg, i.p.) significantly reduced the no-reflow area. In another series of experiments, human coronary artery endothelial cells (HCAEC) were treated with CRP at clinically relevant concentrations (5-25 μg/mL). C-Reactive protein significantly increased COX-1 and COX-2 levels in a time- and concentration-dependent manner. In addition, extracellular signal-regulated kinase (ERK) and Jun N-terminal kinase (JNK) were activated in CRP (5, 10, 25 μg/mL)-treated HCAEC cultures. Furthermore, the ERK inhibitor pd98059 (30 μmol/L) and the JNK inhibitor sp600125 (10 μmol/L) blocked CRP-induced COX-1 and COX-2 expression for 12 h. Together, the findings of the present study suggest that CRP can promote the development of the no-reflow phenomenon by increasing COX-1 and COX-2 expression, which is regulated, in part, via ERK and JNK activity.

Prostacyclin protects vascular integrity via PPAR/14-3-3 pathway

Vascular integrity is protected by the lining endothelial cells (ECs) through structural and molecular protective mechanisms. In response to external stresses, ECs are dynamic in producing protective molecules such as prostacyclin (PGI2). PGI2 is known to inhibit platelet aggregation and controls smooth muscle cell contraction via IP receptors. Recent studies indicate that PGI2 defends endothelial survival and protects vascular smooth muscle cell from apoptosis via peroxisome-proliferator activated receptors (PPAR). PPAR activation results in 14-3-3 upregulation. Increase in cytosolic 14-3-3ɛ or 14-3-3β enhances binding and sequestration of Akt-mediated phosphorylated Bad and reduces Bad-mediated apoptosis via the mitochondrial pathway. Experimental data indicate that administration of PGI2 analogs or augmentation of PGI2 production by gene transfer attenuates endothelial damage and organ infarction caused by ischemia-reperfusion injury. The protective effect of PGI2 is attributed in part to preserving endothelial integrity.

Angiotensin II increases the expression of (pro)renin receptor during low-salt conditions

BACKGROUND

Evidence indicates that chronic angiotensin II (AngII) infusion increases (pro)renin receptor ((P)RR) expression in renal inner medullary collecting duct (IMCD) cells. Recently, it has been shown that renal (P)RR expression is augmented during a low-salt (LS) diet. However, the role of AngII in mediating the stimulation of (P)RR during LS conditions is unknown. We hypothesized that AngII mediates the increased expression of (P)RR during low-salt conditions in IMCDs.

METHODS

(P)RR expression and AngII levels were evaluated in Sprague-Dawley rats fed a LS diet (0.03% NaCl) and normal salt (NS; 0.4% NaCl) for 7 days. We examined the effects of sodium reduction (130 mM NaCl) and AngII on (P)RR expression in IMCDs isolated in hypertonic conditions (640 mOsmol/L with 280 mM NaCl).

RESULTS

Plasma renin activity in LS rats was significantly higher than rats fed with NS (28.1 ± 2.2 versus 6.7 ± 1.1 ng AngI·mL⁻¹·hr⁻¹; P < 0.05), as well as renin content in renal cortex and medulla. The (P)RR mRNA and protein levels were higher in medullary tissues from LS rats but did not change in the cortex. Intrarenal AngII was augmented in LS compared with NS rats (cortex: 710 ± 113 versus 277 ± 86 fmol/g, P < 0.05; medulla: 2093 ± 125 versus 1426 ± 126 fmol/g, P < 0.05). In cultured IMCDs, (P)RR expression was increased in response to LS or AngII treatment and potentiated by both treatments (both at 640 mOsmol/L).

CONCLUSIONS

These data indicate that (P)RR is augmented in medullary collecting ducts in response to LS and that this effect is further enhanced by the increased intrarenal AngII content.

Functional interaction between cyclooxygenase-2 and p53 in response to an endogenous electrophile

Cyclooxygenase-2 (Cox-2) is rapidly expressed by various stimuli and plays a key role in conversion of free arachidonic acid to prostaglandins. We have previously identified 4-hydroxy-2-nonenal (HNE), a lipid peroxidation-derived electrophile, as the potent Cox-2 inducer in rat epithelial RL34 cells and revealed that the HNE-induced Cox-2 expression resulted from the stabilization of Cox-2 mRNA that is mediated by the p38 mitogen-activated protein kinase signaling pathway. In the present study, we investigated an alternative regulatory mechanism of Cox-2 expression mediated by a transcription factor p53. In addition, to characterize the causal role for Cox-2, we examined the effects of Cox-2 overexpression in RL34 cells. To examine whether the HNE-induced Cox-2 expression was mechanistically linked to the p53 expression, we analyzed changes in Cox-2 and p53 expression levels in response to HNE and observed that the Cox-2 levels were inversely correlated with the p53 levels. Down-regulation of p53 followed by the activation of a transcription factor Sp1 was suggested to be involved in the HNE-induced Cox-2 gene expression. To characterize the effect of Cox-2 expression in the cells, we established the Cox-2-overexpressing derivatives of RL34 cells by stable transfection with Cox-2 cDNA. An oligonucleotide microarray analysis revealed a dramatic down-regulation of the proteasome subunit RC1 in the Cox-2 overexpressed cells compared to the empty-vector transfected control cells. Consistent with the Cox-2-mediated down-regulation of proteasome, a moderate reduction of the proteasome activities was observed. This proteasome dysfunction mediated by the Cox-2 overproduction was associated with the enhanced accumulation of p53 and ubiquitinated proteins, leading to the enhanced sensitivity toward electrophiles. These results suggest the existence of a causal link between Cox-2 and p53, which may represent a toxic mechanism of electrophilic lipid peroxidation products.

Mechanisms of exercise-induced cardioprotection

Myocardial ischemia-reperfusion (IR) injury can cause ventricular cell death and is a major pathological event leading to morbidity and mortality in those with coronary artery disease. Interestingly, as few as five bouts of exercise on consecutive days can rapidly produce a cardiac phenotype that resists IR-induced myocardial injury. This review summarizes the development of exercise-induced cardioprotection and the mechanisms responsible for this important adaptive response.

Non-invasive assessment of animal exercise stress: real-time PCR of GLUT4, COX2, SOD1 and HSP70 in avalanche military dog saliva

Exercise has been shown to increase mRNA expression of a growing number of genes. The aim of this study was to assess if mRNA expression of the metabolism- and oxidative stress-related genes GLUT4 (glucose transporter 4), COX2 (cyclooxygenase 2), SOD1 (superoxide dismutase 1) and HSP70 (heat shock protein 70) in saliva changes following acute exercise stress in dogs. For this purpose, 12 avalanche dogs of the Italian Military Force Guardia di Finanza were monitored during simulation of a search for a buried person in an artificial avalanche area. Rectal temperature (RT) and saliva samples were collected the day before the trial (T0), immediately after the descent from a helicopter at the onset of a simulated avalanche search and rescue operation (T1), after the discovery of the buried person (T2) and 2 h later (T3). Expressions of GLUT4, SOD1, COX2 and HSP70 were measured by real-time PCR. The simulated avalanche search and rescue operation was shown to exert a significant effect on RT, as well as on the expression of all metabolism- and oxidative stress-related genes investigated, which peaked at T2. The observed expression patterns indicate an acute exercise stress-induced upregulation, as confirmed by the reductions in expression at T3. Moreover, our findings indicate that saliva is useful for assessing metabolism- and oxidative stress-related genes without the need for restraint, which could affect working dog performance.

d-limonene suppresses doxorubicin-induced oxidative stress and inflammation via repression of COX-2, iNOS, and NFκB in kidneys of Wistar rats

d-limonene is a naturally occurring monoterpene and has been found to posses numerous therapeutic properties. In this study, we used d-limonene as a protective agent against the nephrotoxic effects of anticancer drug doxorubicin (Dox). Rats were given d-limonene at doses of 5% and 10% mixed with diet for 20 consecutive days. Dox was give at the dose of 20 mg/kg body weight intraperitoneally. The protective effects of d-limonene on Dox-induced oxidative stress and inflammation were investigated by assaying oxidative stress biomarkers, lipid peroxidation, serum toxicity markers, proinflammatory cytokines, and expression of nuclear factor kappa B (NFκB), cyclo-oxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS) and Nitrite levels. Administration of Dox (20 mg/kg body weight) in rats enhanced renal lipid peroxidation; depleted glutathione content and anti-oxidant enzymes; elevated levels of kidney toxicity markers viz. kidney injury molecule-1 (KIM-1), blood urea nitrogen (BUN), and creatinine; enhanced expression of NFκB, COX-2, and iNOS and nitric oxide. Treatment with d-limonene prevented oxidative stress by restoring the levels of antioxidant enzymes, further both doses of 5% and 10% showed significant decrease in inflammatory response. Both the doses of d-limonene significantly decreased the levels of kidney toxicity markers KIM-1, BUN, and creatinine. d-limonene also effectively decreased the Dox induced overexpression of NF-κB, COX-2, and iNOS and nitric oxide. Data from the present study indicate the protective role of d-limonene against Dox-induced renal damage.

Knockdown of TRPM8 suppresses cancer malignancy and enhances epirubicin-induced apoptosis in human osteosarcoma cells

As the function of transient receptor potential melastatin member 8 (TRPM8) in osteosarcoma is still unknown, we aim to investigate the possible effects and potential mechanisms of TRPM8 on cell proliferation, metastasis and chemosensitivity in osteosarcoma cells. We find that TRPM8 is aberrantly over-expressed in human osteosarcoma tissues and cell lines. Knockdown of TRPM8 by siRNA in osteosarcoma cells leads to the impaired regulation of intracellular Ca(2+) concentration and then the Akt-GSK-3β pathway and the phosphorylation of p44/p42 and FAK are suppressed. Knockdown of TRPM8 not only negatively influences the cell proliferation and metastasis but also enhances epirubicin-induced cell apoptosis. Such results reveal that TRPM8 is worthy further investigation for its potential as a clinical biomarker and therapeutic target in osteosarcoma.

Protective induction of Hsp70 in heat-stressed primary myoblasts: Involvement of MAPKs

The involvement of extracellular signal-regulated kinases 1 and 2 (ERK1,2), stress kinase p38 and c-Jun NH2 -terminal kinases 1 and 2 (JNK1,2) on Hsp70-upregulation following mild heat shock, and resulting cell protection, was studied on rabbit primary myoblasts. Cells subjected to heat stress (42°C; 60 min) showed a significantly enhanced amount of heat-shock-induced protein 70 (Hsp70), correlating with sustained phosphorylation of MAP kinases ERK1,2, inhibition of p38 and JNK1,2 activation. Induced Hsp70 did not autocrinally suppress activation of transcription factor c-Jun, suggesting involvement of the latter in the protection of myoblasts following heat shock. The inhibition of stress kinases p38, JNK1,2, and MEK1,2 by SP600125, SB203580, and UO126, respectively, established the involvement of JNK1,2 and p38 as upstream, and ERK1,2 as downstream targets of Hsp70 induction. Moreover, the effect of the MEK1,2 inhibitor UO126 revealed a new pathway of c-Jun activation by ERK1,2 in myogenic heat-stressed stem cells. The presented data show that transient activation of JNK1, JNK2, and p38 is necessary for Hsp70 induction and ensuing cell protection. In conclusion, affecting myogenic stem cell protective mechanisms might be a useful strategy in improving stem cell survival and their expanded application in therapy.

BNC Protects H9c2 Cardiomyoblasts from H 2 O 2 -Induced Oxidative Injury through ERK1/2 Signaling Pathway

Buchang naoxintong capsule (BNC) is a traditional Chinese medicine approved for the treatment of cerebrovascular and cardiovascular diseases. However, little is known about the specific protective function or mechanism by which BNC protects against myocardial injury. This research was designed to investigate the cardioprotective effects of BNC in vitro model of hydrogen peroxide (H₂O₂)-induced H9c2 rat cardiomyoblasts. BNC intestinal absorption liquid was used in this study instead of drug-containing serum or extracting solution. Our study revealed that BNC preconditioning enhanced antioxidant function by increasing the activities of total-antioxygen capacity, total-superoxide dismutase, and catalase and by decreasing the production of reactive oxygen species and malondialdehyde. BNC preconditioning also activated extracellular signal-regulated kinases (ERK1/2) and inhibited apoptosis-related proteins such as poly ADP-ribose polymerase (PARP) and caspase-3. Additionally, preincubation with BNC reduced intracellular Ca²⁺ concentration, improved mitochondrial membrane potential, and decreased the apoptosis rate of H9c2 cells in a dose-dependent manner. These data demonstrated that BNC protects H9c2 cardiomyoblasts from H₂O₂-induced oxidative injury by increasing antioxidant abilities, activating ERK1/2, and blocking Ca²⁺-dependent and mitochondria-mediated apoptosis. Based on our results, the potency of BNC for protecting H9c2 cells from oxidative damage is comparable to that of trimetazidine.

Eicosanoid modulation by the short-chain fatty acid n-butyrate in human monocytes

n-Butyrate deriving from bacterial fermentation in the mammalian intestine is a key determinant in gastrointestinal homeostasis. We examined the effects of this short-chain fatty acid and Toll-like receptor 2 (TLR) and TLR4 engagement on inflammatory/immunity-associated genes, cyclo-oxygenases (COXs), prostaglandins (PGs) and leukotrienes (LTs) in human monocytes. Before RNA isolation, freshly isolated human monocytes were co-incubated for different time-points with 1 mm n-butyrate alone or in combination with bacterial stimuli. Based on a knowledge-driven approach, a signature of 180 immunity/inflammation-associated genes was picked and real-time PCR analysis was performed. Pathway analysis was carried out using a web-based database analysing program. Based on these gene expression studies the findings were evaluated at the protein/mediator level by Western blot analysis, FACS and ELISA. Following co-incubation with n-butyrate and lipopolysaccharide, key enzymes of the eicosanoid pathway, like PTGS2 (COX-2), TXS, ALOX5, LTA4H and LTC4S, were significantly up-regulated compared with stimulation with lipopolysaccharide alone. Furthermore, release of the lipid mediators PGE(2), 15d-PGJ(2), LTB(4) and thromboxane B(2) was increased by n-butyrate. Regarding signalling, n-butyrate had no additional effect on mitogen-activated protein kinase and interfered differently with early and late phases of nuclear factor-κB signalling. Our results suggest that among many other mediators of eicosanoid signalling n-butyrate massively induces PGE(2) production by increasing the expression of PTGS2 (COX-2) in monocytes following TLR4 and TLR2 activation and induces secretion of LTB(4) and thromboxane B(2). This underscores the role of n-butyrate as a crucial mediator of gut-specific immunity.

Prostacyclin and PPARα agonists control vascular smooth muscle cell apoptosis and phenotypic switch through distinct 14-3-3 isoforms

We hypothesized that prostacyclin (PGI₂) protects vascular smooth muscle cell (VSMC) against apoptosis and phenotypic switch through peroxisome proliferator-activated receptor-α (PPARα) activation and 14-3-3 upregulation. Here we showed that transfection of rat aortic VSMC, A-10, with PGI₂-producing vectors, Ad-COPI, resulted in attenuated H₂O₂-induced apoptosis accompanied by a selective increase in 14-3-3β and 14-3-3θ expression. Carbaprostacyclin (cPGI₂) and Wy14,643 exerted a similar effect. The effects of PGI₂ were abrogated by MK886, a PPARα antagonist, but not GSK3787, a PPARδ antagonist. PPARα transfection upregulated 14-3-3β and θ expression and attenuated H₂O₂-induced apoptosis. H₂O₂-induced 14-3-3β but not 14-3-3θ degradation was blocked by a caspase 3 inhibitor. Furthermore, 14-3-3β but not 14-3-3θ overexpression reduced, while 14-3-3β siRNA aggravated apoptosis. VSMC contractile proteins and serum response factor (SRF) were reduced in H₂O₂-treated A-10 cells which were concurrently prevented by caspase 3 inhibitor. By contrast, PGI₂ prevented H₂O₂-induced SM22α and Calponin-1 degradation without influencing SRF. cPGI₂ and Wy14,643 also effectively blocked VSMC phenotypic switch induced by growth factors (GFs). GFs suppressed 14-3-3β, θ, ε and η isoforms and cPGI₂ prevented the decline of β, θ and η, but not ε. 14-3-3θ siRNA abrogated the protective effect of cPGI₂ on SM22α and Calponin-1 while 14-3-3 θ or 14-3-3β overexpression partially restored SM22α. These results indicated that PGI₂ protects VSMCs via PPARα by upregulating 14-3-3β and 14-3-3θ. 14-3-3β upregulation confers resistance to apoptosis whereas 14-3-3θ and β upregulation protects SM22α and Calponin-1 from degradation.

Connective tissue growth factor/CCN2 attenuates β-adrenergic receptor responsiveness and cardiotoxicity by induction of G protein-coupled receptor kinase-5 in cardiomyocytes

Myocardial connective tissue growth factor (CTGF/CCN2) is induced in heart failure, a condition associated with diminution of β-adrenergic receptor (β-AR) responsiveness. Accordingly, we aimed to investigate whether CTGF could play a mechanistic role in regulation of β-AR responsiveness. Concentration-response curves of isoproterenol-stimulated cAMP generation in cardiomyocytes from transgenic mice with cardiac-restricted overexpression of CTGF (Tg-CTGF) or cardiomyocytes pretreated with recombinant human CTGF (rec-hCTGF) revealed marked reduction of both β₁-AR and β₂-AR responsiveness. Consistently, ventricular muscle strips from Tg-CTGF mice stimulated with isoproterenol displayed attenuation of maximal inotropic responses. However, no differences of maximal inotropic responses of myocardial fibers from Tg-CTGF mice and nontransgenic littermate control (NLC) mice were discerned when stimulated with supramaximal concentrations of dibutyryl-cAMP, indicating preserved downstream responsiveness to cAMP. Congruent with a mechanism of desensitization of β-ARs, mRNA and protein levels of G protein-coupled receptor kinase 5 (GRK5) were found isoform-selective upregulated in both cardiomyocytes from Tg-CTGF mice and cardiomyocytes exposed to rec-hCTGF. Corroborating a mechanism of GRK5 in CTGF-mediated control of β-AR sensitivity, Chinese hamster ovary cells pretreated with rec-hCTGF displayed increased agonist- and biased ligand-stimulated β-arrestin binding to β-ARs. Despite increased sensitivity of cardiomyocytes from GRK5-knockout (KO) mice to β-adrenergic agonists, pretreatment of GRK5-KO cardiomyocytes with rec-hCTGF, as opposed to cardiomyocytes from wild-type mice, did not alter β-AR responsiveness. Finally, Tg-CTGF mice subjected to chronic exposure (14 days) to isoproterenol revealed blunted myocardial hypertrophy and preserved cardiac function versus NLC mice. In conclusion, this study uncovers a novel mechanism controlling β-AR responsiveness in cardiomyocytes involving CTGF-mediated regulation of GRK5.