Effect of aerobic exercise on tumor physiology in an animal model of human breast cancer

Exercise as Adjunct Therapy in Cancer

Data from observational studies indicate that both physical activity as well as exercise (ie, structured physical activity) is associated with reductions in the risk of recurrence and cancer mortality after a diagnosis of certain forms of cancer. Emerging evidence from preclinical studies indicates that physical activity/exercise paradigms regulate intratumoral vascular maturity and perfusion, hypoxia, and metabolism and augments the antitumor immune response. Such responses may, in turn, enhance response to standard anticancer treatments. For instance, exercise improves efficacy of chemotherapeutic agents, and there is rationale to believe that it will also improve radiotherapy response. This review overviews the current preclinical as well as clinical evidence supporting exercise modulation of therapeutic response and postulated biological mechanisms underpinning such effects. We also examine the implications for tumor response to radiation, chemotherapy, and immunotherapy.

How to Modulate Tumor Hypoxia for Preclinical In Vivo Imaging Research

Tumor hypoxia is related with tumor aggressiveness, chemo- and radiotherapy resistance, and thus a poor clinical outcome. Therefore, over the past decades, every effort has been made to develop strategies to battle the negative prognostic influence of tumor hypoxia. For appropriate patient selection and follow-up, noninvasive imaging biomarkers such as positron emission tomography (PET) radiolabeled ligands are unprecedentedly needed. Importantly, before being able to implement these new therapies and potential biomarkers into the clinical setting, preclinical in vivo validation in adequate animal models is indispensable. In this review, we provide an overview of the different attempts that have been made to create differential hypoxic in vivo cancer models with a particular focus on their applicability in PET imaging studies.

Chemokine Receptors and Exercise to Tackle the Inadequacy of T Cell Homing to the Tumor Site

While cancer immune therapy has revolutionized the treatment of metastatic disease across a wide range of cancer diagnoses, a major limiting factor remains with regard to relying on adequate homing of anti-tumor effector cells to the tumor site both prior to and after therapy. Adoptive cell transfer (ACT) of autologous T cells have improved the outlook of patients with metastatic melanoma. Prior to the approval of checkpoint inhibitors, this strategy was the most promising. However, while response rates of up to 50% have been reported, this strategy is still rather crude. Thus, improvements are needed and within reach. A hallmark of the developing tumor is the evasion of immune destruction. Achieved through the recruitment of immune suppressive cell subsets, upregulation of inhibitory receptors and the development of physical and chemical barriers (such as poor vascularization and hypoxia) leaves the microenvironment a hostile destination for anti-tumor T cells. In this paper, we review the emerging strategies of improving the homing of effector T cells (TILs, CARs, TCR engineered T cells, etc.) through genetic engineering with chemokine receptors matching the chemokines of the tumor microenvironment. While this strategy has proven successful in several preclinical models of cancer and the strategy has moved into the first phase I/II clinical trial in humans, most of these studies show a modest (doubling) increase in tumor infiltration of effector cells, which raises the question of whether road blocks must be tackled for efficient homing. We propose a role for physical exercise in modulating the tumor microenvironment and preparing the platform for infiltration of anti-tumor immune cells. In a time of personalized medicine and genetic engineering, this "old tool" may be a way to augment efficacy and the depth of response to immune therapy.

Dual antiplatelet therapy with clopidogrel and aspirin increases mortality in 4T1 metastatic breast cancer-bearing mice by inducing vascular mimicry in primary tumour

Platelet inhibition has been considered an effective strategy for combating cancer metastasis and compromising disease malignancy although recent clinical data provided evidence that long-term platelet inhibition might increase incidence of cancer deaths in initially cancer-free patients. In the present study we demonstrated that dual anti-platelet therapy based on aspirin and clopidogrel (ASA+Cl), a routine regiment in cardiovascular patients, when given to cancer-bearing mice injected orthotopically with 4T1 breast cancer cells, promoted progression of the disease and reduced mice survival in association with induction of vascular mimicry (VM) in primary tumour. In contrast, treatment with ASA+Cl or platelet depletion did reduce pulmonary metastasis in mice, if 4T1 cells were injected intravenously. In conclusion, distinct platelet-dependent mechanisms inhibited by ASA+Cl treatment promoted cancer malignancy and VM in the presence of primary tumour and afforded protection against pulmonary metastasis in the absence of primary tumour. In view of our data, long-term inhibition of platelet function by dual anti-platelet therapy (ASA+Cl) might pose a hazard when applied to a patient with undiagnosed and untreated malignant cancer prone to undergo VM.

Exercise and the Tumor Microenvironment: Potential Therapeutic Implications

An imbalance in oxygen delivery to demand in solid tumors results in local areas of hypoxia leading to poor prognosis for the patient. We hypothesize that aerobic exercise increases tumor blood flow, recruits previously nonperfused tumor blood vessels, and thereby augments blood-tumor O2 transport and diminishes tumor hypoxia. When combined with conventional anticancer treatments, aerobic exercise can significantly improve the outcomes for several types of cancers.

Voluntary exercise slows breast tumor establishment and reduces tumor hypoxia in ApoE-/- mice

Exercise reduces the risk of breast cancer development and improves survival in breast cancer patients. However, the underlying mechanisms of this protective effect remain to be fully elucidated, and it is unclear whether exercise can attenuate the protumor effects of obesity and related hyperlipidemia on breast cancer growth and development. We hypothesized that exercise attenuates the negative effect of hyperlipidemia through normalization of the tumor microenvironment and improved T cell infiltrate. Hyperlipidemic ApoE^-/- mice with orthotopic EO771 breast tumors were randomly assigned to one of two voluntary running groups or sedentary controls, and muscular cytochrome c oxidase subunit IV (COX-IV) expression was used as a biomarker for the level of exercise. Tumors from mice with high muscular COX-IV expression took significantly longer to reach 100 mm³ ( P = 0.008), but showed no difference in growth rate once the tumor was established. Wheel running appeared to reduce internal metastases, but did not affect T cell infiltrate or the proportion of regulatory and cytotoxic T cells within the tumor. Serum levels of monocyte chemoattractant protein-1 (MCP-1) were significantly increased by tumor burden ( P = 0.02) and correlated with spleen weight ( P < 0.0001, R = 0.65). Furthermore, tumor hypoxia was significantly decreased in mice with high muscular COX-IV expression ( P = 0.01). Taken together, these results indicate that wheel running can slow the establishment of primary and secondary EO771 breast tumors and induce beneficial changes in the breast tumor microenvironment in ApoE^-/- mice. NEW & NOTEWORTHY In this first study to investigate the effect of exercise on tumor behavior in a hyperlipidemic model, we hypothesized that wheel running would counteract the protumorigenic environment generated by hyperlipidemia. Wheel running slowed establishment of primary and secondary tumors and reduced tumor hypoxia but did not affect exponential tumor growth in ApoE^-/- mice. Overall, voluntary wheel running induced favorable microenvironmental changes in breast tumors.

Transport of drugs from blood vessels to tumour tissue

The effectiveness of anticancer drugs in treating a solid tumour is dependent on delivery of the drug to virtually all cancer cells in the tumour. The distribution of drug in tumour tissue depends on the plasma pharmacokinetics, the structure and function of the tumour vasculature and the transport properties of the drug as it moves through microvessel walls and in the extravascular tissue. The aim of this Review is to provide a broad, balanced perspective on the current understanding of drug transport to tumour cells and on the progress in developing methods to enhance drug delivery. First, the fundamental processes of solute transport in blood and tissue by convection and diffusion are reviewed, including the dependence of penetration distance from vessels into tissue on solute binding or uptake in tissue. The effects of the abnormal characteristics of tumour vasculature and extravascular tissue on these transport properties are then discussed. Finally, methods for overcoming limitations in drug transport and thereby achieving improved therapeutic results are surveyed.

The Linkage between Breast Cancer, Hypoxia, and Adipose Tissue

OBJECTIVE

The development of breast cancer cells is linked to hypoxia. The hypoxia-induced factor HIF-1α influences metastasis through neovascularization. Hypoxia seems to decrease the responsiveness to hormonal treatment due to loss of estrogen receptors (ERs). Obesity is discussed to increase hypoxia in adipocytes, which promotes a favorable environment for tumor cells in mammary fat tissue, whereas, tumor cells profit from good oxygen supply and are influenced by its deprivation as target regions within tumors show. This review gives an overview of the current state on research of hypoxia and breast cancer in human adipose tissue.

METHODS

A systematic literature search was conducted on PubMed (2000-2016) by applying hypoxia and/or adipocytes and breast cancer as keywords. Review articles were excluded as well as languages other than English or German. There was no restriction regarding the study design or type of breast cancer. A total of 35 papers were found. Eight studies were excluded due to missing at least two of the three keywords. One paper was removed due to Russian language, and one was dismissed due to lack of adherence. Seven papers were identified as reviews. After applying exclusion criteria, 18 articles were eligible for inclusion.

RESULTS

Two articles describe the impairment of mammary epithelial cell polarization through hypoxic preconditioning. A high amount of adipocytes enhances cancer progression due to the increased expression of HIF-1α which causes the loss of ER α protein as stated in four articles. Four articles analyzed that increased activation of HIF's induces a series of transcriptions resulting in tumor angiogenesis. HIF inhibition, especially when combined with cytotoxic chemotherapy, holds strong potential for tumor suppression as stated in further four articles. In two articles there is evidence of a strong connection between hypoxia, oxidative stress and a poor prognosis for breast cancer via HIF regulated pathways. Acute hypoxia seems to normalize the microenvironment in breast cancer tissue and has proven to affect tumor growth positively as covered in two articles.

CONCLUSION

This review indicates that the development of breast cancer is influenced by hypoxia. A high amount of adipocytes enhances cancer progression due to the increased expression of HIF-1α.

Exercise-dependent regulation of the tumour microenvironment

The integrity and composition of the tumour microenvironment (TME) is highly plastic, undergoing constant remodelling in response to instructive signals derived from alterations in the availability and nature of systemic host factors. This 'systemic milieu' is directly modulated by host exposure to modifiable lifestyle factors such as exercise. Host exposure to regular exercise markedly reduces the risk of the primary development of several cancers and might improve clinical outcomes following a diagnosis of a primary disease. However, the molecular mechanisms that underpin the apparent antitumour effects of exercise are poorly understood. In this Opinion article, we explore the putative effects of exercise in reprogramming the interaction between the host and the TME. Specifically, we speculate on the possible effects of exercise on reprogramming 'distant' tissue microenvironments (those not directly involved in the exercise response) by analysing how alterations in the systemic milieu might modulate key TME components to influence cancer hallmarks.

CCL28 promotes breast cancer growth and metastasis through MAPK-mediated cellular anti-apoptosis and pro-metastasis

Breast cancer is one of the most commonly diagnosed cancers worldwide and the second leading cause of cancer-related deaths among females. CCL28 (mucosa-associated epithelial chemokine, MEC), a CC subfamily chemokine, has been well studied in the process of inflammation, and recently increasing evidence indicates that CCL28 is related to tumor progression. However, little is known concerning its function in breast cancer. In the present study, we generated a CCL28-overexpressing breast cancer cell line MDA-MB-231HM/CCL28 from parental MDA-MB-231HM cells. We found that overexpression of CCL28 promoted cell proliferation and tumor formation, and also enhanced migration, invasion and metastasis both in vitro and in vivo. Mechanistic studies revealed that CCL28 mediated intracellular activation of the mitogen-activated protein kinase (MAPK) signaling pathway to promote breast cancer cell proliferation and metastasis by upregulating anti-apoptotic protein Bcl-2 and suppressing cell adhesion protein β-catenin. However, overexpression of CCL28 did not influence the expression of metastasis-related protein matrix metalloproteinase MMP2 and MMP9 and VEGF. Tissue sample analysis from animal models also indicated that overexpression of CCL28 was associated with enhanced pERK expression and reduced β-catenin expression in breast carcinomas. Thus, our results show for the first time that CCL28 contributes to breast cancer progression through the ERK/MAPK-mediated anti-apoptotic and metastatic signaling pathway. Antagonists of CCL28 and the MAPK signaling pathway may be used synergistically to treat breast cancer patients.

The role of the chemokine receptor XCR1 in breast cancer cells

Considerable attention has recently been paid to the application of chemokines to cancer immunotherapy due to their complex role in cell proliferation, invasion, metastasis, and tumorigenesis, which extends beyond the regulation of lymphocyte migration during immune responses. The expression and the function of the chemokine receptor XCR1 on breast cancer have remained elusive to date. In this study, the expressions of XCR1 mRNA were tested by quantitative real-time polymerase chain reaction in one breast epithelial cell line (MCF-10A) and nine breast cancer cell lines (MDA-MB-231, 231HM, 231BO, MDA-MB-468, MCF-7, T47D, Bcap-37, ZR-75-30, and SK-BR-3). We established XCR1-overexpressing breast cancer cell line MDA-MB-231 (231/XCR1) in XCR1 low expression cell line MDA-MB-231 (231). The ability of proliferation, invasion, and metastasis was measured by CCK8, plate cloning formation, and transwell analysis, respectively, in XCR1-overexpressing breast cancer cell lines (231/XCR1) and their parental cell line MDA-MB-231/Vector (simplified as “231/Vector”); 5×10⁶/100 μL cells were inoculated in mammary fat pad of BALB/c nude mice. There were six BALB/c nude mice in the experimental group and control group. Protein expression was analyzed by cell immunofluorescence and Western blot. The growth of XCR1-overexpressing human breast cancer cell line MDA-MB-231 in vitro was restrained and tumorigenesis in vivo was also extenuated, its mechanism may involve in the inhibition of MAPK and PI3K/AKT/mTOR signaling pathway, but increase in LC3 expression. However, the overexpression of XCR1 in human breast cancer cell line MDA-MB-231 in vitro can promote the migration and invasion partially due to decreasing the protein level of β-catenin. Therefore, XCR1 can affect the biological characteristics of some special breast cancer cells through complex signal transduction pathway.

Tumor vessel normalization after aerobic exercise enhances chemotherapeutic efficacy

Targeted therapies aimed at tumor vasculature are utilized in combination with chemotherapy to improve drug delivery and efficacy after tumor vascular normalization. Tumor vessels are highly disorganized with disrupted blood flow impeding drug delivery to cancer cells. Although pharmacologic anti-angiogenic therapy can remodel and normalize tumor vessels, there is a limited window of efficacy and these drugs are associated with severe side effects necessitating alternatives for vascular normalization. Recently, moderate aerobic exercise has been shown to induce vascular normalization in mouse models. Here, we provide a mechanistic explanation for the tumor vascular normalization induced by exercise. Shear stress, the mechanical stimuli exerted on endothelial cells by blood flow, modulates vascular integrity. Increasing vascular shear stress through aerobic exercise can alter and remodel blood vessels in normal tissues. Our data in mouse models indicate that activation of calcineurin-NFAT-TSP1 signaling in endothelial cells plays a critical role in exercise-induced shear stress mediated tumor vessel remodeling. We show that moderate aerobic exercise with chemotherapy caused a significantly greater decrease in tumor growth than chemotherapy alone through improved chemotherapy delivery after tumor vascular normalization. Our work suggests that the vascular normalizing effects of aerobic exercise can be an effective chemotherapy adjuvant.

Efficacy and Mechanisms of Aerobic Exercise on Cancer Initiation, Progression, and Metastasis: A Critical Systematic Review of In Vivo Preclinical Data

A major objective of the emerging field of exercise-oncology research is to determine the efficacy of, and biological mechanisms by which, aerobic exercise affects cancer incidence, progression, and/or metastasis. There is a strong inverse association between self-reported exercise and the primary incidence of several forms of cancer; similarly, emerging data suggest that exercise exposure after a cancer diagnosis may improve outcomes for early-stage breast, colorectal, or prostate cancer. Arguably, critical next steps in the development of exercise as a candidate treatment in cancer control require preclinical studies to validate the biological efficacy of exercise, identify the optimal "dose", and pinpoint mechanisms of action. To evaluate the current evidence base, we conducted a critical systematic review of in vivo studies investigating the effects of exercise in cancer prevention and progression. Studies were evaluated on the basis of tumor outcomes (e.g., incidence, growth, latency, metastasis), dose-response, and mechanisms of action, when available. A total of 53 studies were identified and evaluated on tumor incidence (n = 24), tumor growth (n = 33), or metastasis (n = 10). We report that the current evidence base is plagued by considerable methodologic heterogeneity in all aspects of study design, endpoints, and efficacy. Such heterogeneity precludes meaningful comparisons and conclusions at present. To this end, we provide a framework of methodologic and data reporting standards to strengthen the field to guide the conduct of high-quality studies required to inform translational, mechanism-driven clinical trials. Cancer Res; 76(14); 4032-50. ©2016 AACR.

Long-term exercise training as a modulator of mammary cancer vascularization

BACKGROUND

Breast cancer remains a leading cause of death by cancer worldwide. It is commonly accepted that angiogenesis and the expression of angiogenic factors such as vascular endothelial growth factor-A (VEGF-A) is associated with the increased risk of metastasis and poor patient outcome.

OBJECTIVE

This work aimed to evaluate the effects of long-term exercise training on the growth and vascularization of mammary tumors in a rat model.

MATERIALS AND METHODS

Fifty female Sprague-Dawley rats were divided into four groups: two N-methyl-N-nitrosourea (MNU)-exposed groups (exercised and sedentary) and two control groups (exercised and sedentary). MNU was administered once, intraperitoneally at 7 weeks-old. Animals were then exercised on a treadmill for 35 weeks. Mammary tumors were evaluated using thermography, ultrasonography [Power Doppler (PDI), B Flow and contrast-enhanced ultrasound (CEUS)], and immunohistochemistry (VEGF-A).

RESULTS

Both, MNU sedentary and exercised groups showed 100% of tumor incidence, but exercised animals showed less tumors with an increased latency period. Exercise training also enhanced VEGF-A immunoexpression and vascularization (microvessel density, MVD) (p<0.05), and reduced histological aggressiveness. Ultrasound and thermal imaging analysis confirmed the enhanced vascularization of tumors on exercised animals.

CONCLUSION

Long-term exercise training increased VEGF-A expression, leading to enhanced tumor vascularization and reduced tumor burden, multiplicity and histological aggressiveness.

MicroRNA-206, let-7a and microRNA-21 pathways involved in the anti-angiogenesis effects of the interval exercise training and hormone therapy in breast cancer

AIMS

MicroRNAs (miRNAs) are the targeting signal-transduction pathways that can mediate tumorigenesis via their down and/or up-regulation. For example, miR-21 and miR-206 can effect on the tumor angiogenesis as an oncomir and a tumor suppressor, respectively.

MATERIALS AND METHODS

The present study is aimed to investigate the effects of the interval exercise training in combination with tamoxifen and/or letrozole on miR-21, miR-206 and let-7 as well as their underlying pathways in regard to tumor angiogenesis in sixty four mice with breast tumor. ELISA, immunohistochemistry, qRT-PCR assays were performed accomplish the study.

KEY FINDINGS

The results showed that the tumor size was significantly declined in the exercise training, tamoxifen and letrozole groups compared to tumor group. Mir-206 and let-7 were up-regulated, and mir-21 expression was down-regulated in the exercise training compared to tumor group. Exercise training decreased the expression of ER-α, HIF-α, VEGF, CD31 and Ki67 in tumor tissue. The combination tamoxifen and/or letrozole with the exercise training could down-regulate the expression of ERα, miR-21, HIF-1α, TNF-α, CD31, Ki67 and VEGF, and up-regulate the expression of miR-206, PDCD-4, let-7 and IL-10 that led to reducing the angiogenesis and tumor growth.

SIGNIFICANCE

Our results showed that miR-21, miR-206 and let-7a pathways may involve in the anti-angiogenesis effects of the interval exercise training with hormone therapy in mice model of breast tumor.

Fortifying the Treatment of Prostate Cancer with Physical Activity

Over the past decade, significant data have shown that obese men experience a survival detriment after treatment for prostate cancer. While methods to combat obesity are of utmost importance for the prostate cancer patient, newer data reveal the overall metabolic improvements that accompany increased activity levels and intense exercise beyond weight loss. Along these lines, a plethora of data have shown improvement in prostate cancer-specific outcomes after treatment accompanied with these activity levels. This review discusses the metabolic mechanisms in which increased activity levels and exercise can help improve both outcomes for men treated for prostate cancer while lowering the side effects of treatment.

Dysregulated metabolism contributes to oncogenesis

Cancer is a disease characterized by unrestrained cellular proliferation. In order to sustain growth, cancer cells undergo a complex metabolic rearrangement characterized by changes in metabolic pathways involved in energy production and biosynthetic processes. The relevance of the metabolic transformation of cancer cells has been recently included in the updated version of the review "Hallmarks of Cancer", where dysregulation of cellular metabolism was included as an emerging hallmark. While several lines of evidence suggest that metabolic rewiring is orchestrated by the concerted action of oncogenes and tumor suppressor genes, in some circumstances altered metabolism can play a primary role in oncogenesis. Recently, mutations of cytosolic and mitochondrial enzymes involved in key metabolic pathways have been associated with hereditary and sporadic forms of cancer. Together, these results demonstrate that aberrant metabolism, once seen just as an epiphenomenon of oncogenic reprogramming, plays a key role in oncogenesis with the power to control both genetic and epigenetic events in cells. In this review, we discuss the relationship between metabolism and cancer, as part of a larger effort to identify a broad-spectrum of therapeutic approaches. We focus on major alterations in nutrient metabolism and the emerging link between metabolism and epigenetics. Finally, we discuss potential strategies to manipulate metabolism in cancer and tradeoffs that should be considered. More research on the suite of metabolic alterations in cancer holds the potential to discover novel approaches to treat it.

Physical Activity and Prostate Tumor Vessel Morphology: Data from the Health Professionals Follow-up Study

Vigorous activity is associated with lower risk of prostate cancer progression, but the biologic mechanisms are unknown. Exercise affects vascularization of tumors in animal models, and small, irregularly shaped vessels in prostate tumors are associated with fatal prostate cancer. We hypothesized that men who engaged in vigorous activity or brisk walking would have larger, more regularly shaped vessels in their prostate tumors. We prospectively examined whether physical activity was associated with prostate tumor microvessel morphology among 571 men in the Health Professionals Follow-up Study using ordinal logistic regression. Vessel size (μm(2)), vessel lumen regularity (perimeter(2)/4 · Π · area), and microvessel density (number/high-powered field) were ascertained in tumor sections stained for endothelial cell marker CD34. Vigorous activity [metabolic equivalent task (MET) ≥ 6], nonvigorous activity (MET < 6), and walking pace were assessed a median of 14 months before diagnosis. Prostate tumors from men who reported a brisk walking pace (3+ mph) had larger, more regularly shaped blood vessels compared with those of men who walked at a less than brisk pace [vessel regularity OR, 1.59; 95% confidence interval (CI), 1.11-2.27; P value, 0.01; vessel size OR, 1.48; 95% CI, 1.04-2.12; P value, 0.03]. Brisk walking was not associated with microvessel density; total vigorous and nonvigorous activities were not associated with vessel size, shape, or number. Brisk walking may be associated with larger, more regularly shaped vessels in prostate tumors. Additional research elucidating the effect of physical activity on prostate tumor biology is needed.

Exercise-induced changes in tumour LDH-B and MCT1 expression are modulated by oestrogen-related receptor alpha in breast cancer-bearing BALB/c mice

KEY POINTS

Monocarboxylate transporters (MCTs) and lactate dehydrogenase A (LDH-A) play important roles in sustaining the glycolytic phenotype seen in cancer. Endurance training improves aerobic capacity; however, whether endurance training alters the metabolic phenotype of a solid tumour, from the perspective of lactate metabolism, is yet to be proven. This study showed that endurance training decreases expression of the MCT1 basigin (CD147) and LDH-A , and also increases LDH-B expression in solid tumours and attenuates tumour lactate metabolism. Similar results for MCT1 and LDH-B were found with inhibition of the oestrogen-related receptor alpha (ERRα). The training effects were not additive to the ERRα effects on MCT1 and LDH-B expression in the tumour, which indicated that exercise-induced alterations in MCT1 and LDH-B expression were modulated by ERRα. These results suggest that endurance training could be a useful tool in cancer therapy, especially in basal-like and luminal-like breast carcinomas.

ABSTRACT

Several factors, including overexpression of lactate dehydrogenase (LDH) and monocarboxylate transporters (MCTs), promote an aerobic lactate production that allows some cancer cells to sustain higher proliferation rates in hostile environments outside the cell. To elucidate the effect of endurance training on the metabolic phenotype of solid tumours, we focused on the tumour expression of LDH-A, LDH-B, MCT1, MCT4, oestrogen-related receptor alpha (ERRα) and LDH isozymes in control (C), trained (T), control+XCT790 (CX) and trained+XCT790 (TX) mice. First, we found that the metabolically altered tumours from the trained animals exhibited lower values for lactate concentration than the control group. The decreased lactate concentration was associated with a shift in the tumour LDH isozyme profile towards LDH-1. These exercise-induced changes were also associated with decreases in the expression of the tumour MCT1, ERRα and CD147 in the trained animals. Secondly, the inhibition of ERRα by treatment of MC4-L2 human breast cancer cells with XCT790 (inverse agonist ligand of ERRα) before injection into the animals not only increased LDH-B expression in the tumour, but also decreased MCT1 expression in the CX group in comparison to the C group. The effects of ERRα inhibition were not additive to the training effects on the expressions of MCT1 and LDH-B in the solid tumours. In conclusion, our results suggest that exercise-induced suppression of ERRα expression modulates alterations in solid tumour expression of LDH-B and MCT1 and contributes towards the prevention of tumour development.

Modulation of murine breast tumor vascularity, hypoxia and chemotherapeutic response by exercise

Exercise has been shown to improve postischemia perfusion of normal tissues; we investigated whether these effects extend to solid tumors. Estrogen receptor-negative (ER-, 4T1) and ER+ (E0771) tumor cells were implanted orthotopically into syngeneic mice (BALB/c, N = 11-12 per group) randomly assigned to exercise or sedentary control. Tumor growth, perfusion, hypoxia, and components of the angiogenic and apoptotic cascades were assessed by MRI, immunohistochemistry, western blotting, and quantitative polymerase chain reaction and analyzed with one-way and repeated measures analysis of variance and linear regression. All statistical tests were two-sided. Exercise statistically significantly reduced tumor growth and was associated with a 1.4-fold increase in apoptosis (sedentary vs exercise: 1544 cells/mm(2), 95% CI = 1223 to 1865 vs 2168 cells/mm(2), 95% CI = 1620 to 2717; P = .048), increased microvessel density (P = .004), vessel maturity (P = .006) and perfusion, and reduced intratumoral hypoxia (P = .012), compared with sedentary controls. We also tested whether exercise could improve chemotherapy (cyclophosphamide) efficacy. Exercise plus chemotherapy prolonged growth delay compared with chemotherapy alone (P < .001) in the orthotopic 4T1 model (n = 17 per group). Exercise is a potential novel adjuvant treatment of breast cancer.

Voluntary exercise prevents cisplatin-induced muscle wasting during chemotherapy in mice

Loss of muscle mass related to anti-cancer therapy is a major concern in cancer patients, being associated with important clinical endpoints including survival, treatment toxicity and patient-related outcomes. We investigated effects of voluntary exercise during cisplatin treatment on body weight, food intake as well as muscle mass, strength and signalling. Mice were treated weekly with 4 mg/kg cisplatin or saline for 6 weeks, and randomized to voluntary wheel running or not. Cisplatin treatment induced loss of body weight (29.8%, P < 0.001), lean body mass (20.6%, P = 0.001), as well as anorexia, impaired muscle strength (22.5% decrease, P < 0.001) and decreased glucose tolerance. In addition, cisplatin impaired Akt-signalling, induced genes related to protein degradation and inflammation, and reduced muscle glycogen content. Voluntary wheel running during treatment attenuated body weight loss by 50% (P < 0.001), maintained lean body mass (P < 0.001) and muscle strength (P < 0.001), reversed anorexia and impairments in Akt and protein degradation signalling. Cisplatin-induced muscular inflammation was not prevented by voluntary wheel running, nor was glucose tolerance improved. Exercise training may preserve muscle mass in cancer patients receiving cisplatin treatment, potentially improving physical capacity, quality of life and overall survival.

Concomitant low-dose doxorubicin treatment and exercise

Cardiotoxicity is a side effect for cancer patients treated with doxorubicin (DOX). We tested the hypothesis that low-intensity aerobic exercise concomitant with DOX treatment would offset DOX-induced cardiotoxicity while also improving the therapeutic efficacy of DOX on tumor progression. B16F10 melanoma cells (3 × 10(5)) were injected subcutaneously into the scruff of 6- to 8-wk-old male C57BL/6 mice (n = 48). A 4 mg/kg cumulative dose of DOX was administered over 2 wk, and exercise (EX) consisted of treadmill walking (10 m/min, 45 min/day, 5 days/wk, 2 wk). Four experimental groups were tested: 1) sedentary (SED) + vehicle, 2) SED + DOX, 3) EX + vehicle, and 4) EX + DOX. Tumor volume was attenuated in DOX and lowest in EX + DOX. DOX-treated animals had less gain in body weight, reduced heart weights (HW), smaller HW-to-body weight ratios, and shorter tibial lengths by the end of the protocol; and exercise did not reverse the cardiotoxic effects of DOX. Despite decreased left ventricular (LV) mass with DOX, cardiomyocyte cross-sectional area, β-myosin heavy chain gene expression, and whole heart systolic (fractional shortening) and diastolic (E/A ratio) function were similar among groups. DOX also resulted in increased LV fibrosis with lower LV end diastolic volume and stroke volume. Myocardial protein kinase B activity was increased with both DOX and EX treatments, and tuberous sclerosis 2 (TSC2) abundance was reduced with EX. Downstream phosphorylation of TSC2 and mammalian target of rapamycin were similar across groups. We conclude that exercise increases the efficacy of DOX in inhibiting tumor growth without mitigating subclinical DOX-induced cardiotoxicity in a murine model of melanoma.

The effect of exercise training on the level of tissue IL-6 and vascular endothelial growth factor in breast cancer bearing mice

OBJECTIVES

The goal of this study was assessing the prophylactic effect of exercise and its role as an adjuvant therapy on level of cytokines involved in angiogenesis in estrogen-dependent breast cancer.

MATERIALS AND METHODS

Forty female BALB/c mice were randomly assigned to exercise-tumor-exercise (ETE), exercise-tumor-rest (ETR), rest-tumor-exercise (RTE) and rest-tumor-rest (RTR) groups. After orientation in the environment, two groups of mice performed continuous endurance exercise for 8 weeks, and thereafter estrogen-dependent MC4L2 cancer cells were injected to them. Then, one group of each of trained and non-trained mice performed endurance exercise 5 days per week for 6 weeks. Tumor volume was measured by a digital caliper weekly. Finally, the mice were sacrificed; tumor tissue was removed, immediately frozen and kept in -70°C. Tumor sample was homogenized; levels of cytokines were measured and quantified using ELISA.

RESULTS

There was significant reduction in the level of interlukin-6 (IL-6) (P=0.001), Vascular endothelial growth factor (VEGF) (P=0.0001) and tumor volume (P=0.0001) among the groups performing endurance exercise after malignancy (RTE and ETE) in comparison with groups not performing endurance exercise (ETR and RTR), and these results were in agreement with tumor growth rate.

CONCLUSION

Exercise can cause reduction in levels of pro-inflammatory cytokines in tumor tissue. Decreased IL-6 production could reduce the generation of VEGF, resulting in reduced intra-tumor angiogenesis. Due to reduction of the level of these cytokines in groups doing exercise before and after malignancy, exercise is presumed to be an adjuvant therapy in estrogen-receptor dependent tumors in addition to its effective prophylactic role.

Modulation of blood flow, hypoxia, and vascular function in orthotopic prostate tumors during exercise

BACKGROUND

Previous studies have hypothesized that tumor blood flow may be elevated or reduced during exercise, which could impact the tumor microenvironment. However, to date technical limitations have precluded the measurement of tumor blood flow during exercise. Using an orthotopic preclinical model of prostate cancer, we tested the hypotheses that during exercise tumors would experience 1) diminished vascular resistance, 2) augmented blood flow, 3) increased numbers of perfused vessels, and 4) decreased tissue hypoxia and, furthermore, that the increased perfusion would be associated with diminished vasoconstriction in prostate tumor arterioles.

METHODS

Dunning R-3327 MatLyLu tumor cells were injected into the ventral prostate of male Copenhagen rats aged 4 to 6 months randomly assigned to tumor-bearing (n = 42) or vehicle control (n = 14) groups. Prostate tumor blood flow, vascular resistance, patent vessel number, and hypoxia were measured in vivo in conscious rats at rest and during treadmill exercise, and vasoconstrictor responsiveness of resistance arterioles was investigated in vitro.

RESULTS

During exercise there was a statistically significant increase in tumor blood flow (approximately 200%) and number of patent vessels (rest mean ± standard deviation [SD] = 12.7±1.3; exercise mean ± SD = 14.3±0.6 vessels/field; Student t test two-sided P = .02) and decreased hypoxia compared with measurements made at rest. In tumor arterioles, the maximal constriction elicited by norepinephrine was blunted by approximately 95% vs control prostate vessels.

CONCLUSIONS

During exercise there is enhanced tumor perfusion and diminished tumor hypoxia due, in part, to a diminished vasoconstriction. The clinical relevance of these findings are that exercise may enhance the delivery of tumor-targeting drugs as well as attenuate the hypoxic microenvironment within a tumor and lead to a less aggressive phenotype.

Effects of aerobic exercise on cancer-related fatigue in breast cancer patients receiving chemotherapy: a meta-analysis

Increasing scientific evidences suggest that aerobic exercise may improve cancer-related fatigue in breast cancer patients, but many existing studies have yielded inconclusive results. This meta-analysis aimed to derive a more precise estimation of the effects of aerobic exercise on cancer-related fatigue in breast cancer patients receiving chemotherapy. The PubMed, CISCOM, CINAHL, Web of Science, Google Scholar, EBSCO, Cochrane Library, and CBM databases were searched from inception through July 1, 2013 without language restrictions. Crude standardized mean difference (SMD) with 95 % confidence interval (CI) was calculated. Twelve comparative studies were assessed with a total of 1,014 breast cancer patients receiving chemotherapy, including 522 patients in the aerobic exercise group (intervention group) and 492 patients in the usual care group (control group). The meta-analysis results revealed that the Revised Piper Fatigue Scale (RPFS) scores of breast cancer patients in the intervention group were significantly lower than those in the control group (SMD=-0.82, 95% CI=-1.04 ∼ -0.60, P<0.001). However, there was no significant difference in the Functional Assessment of Chronic Illness Treatment-Fatigue scale (FACIT-F) scores between the intervention and control groups (SMD=0.09, 95% CI=-0.07 ∼ 0.25, P=0.224). Subgroup analysis by ethnicity indicated that there were significant differences in RPFS and FACIT-F scores between the intervention and control groups among Asian populations (RPFS: SMD=-1.08, 95% CI=-1.35 ∼ -0.82, P<0.001; FACIT-F: SMD=1.20, 95 % CI=0.70 ∼1.71, P<0.001), but not among Caucasian populations (all P>0.05). The current meta-analysis indicates that aerobic exercise may improve cancer-related fatigue in breast cancer patients receiving chemotherapy, especially among Asian populations.

Exercise training in transgenic mice is associated with attenuation of early breast cancer growth in a dose-dependent manner

Epidemiological research suggests that regular physical activity confers beneficial effects that mediate an anti-tumor response and may reduce cancer recurrence. It is unclear what amount of physical activity is necessary to exert such a protective effect and what mechanisms are involved. We investigated the effects of voluntary wheel running on tumor progression and cytokine gene expression in the transgenic polyoma middle T oncoprotein (PyMT) mouse model of invasive breast cancer. Runners showed significantly reduced tumor sizes compared with non-runners after 3 weeks of running (p ≤ 0.01), and the greater the running distance the smaller the tumor size (Pearson's r = -0.61, p ≤ 0.04, R(2) = 0.38). Mice running greater than 150 km per week had a significantly attenuated tumor size compared with non-runners (p ≤ 0.05). Adipose tissue mass was inversely correlated with tumor size in runners (Pearson's r = -0.77, p = 0.014) but not non-runners. Gene expression of CCL22, a cytokine associated with recruitment of immunosuppressive T regulatory cells, was decreased in tumors of runners compared to non-runners (p ≤ 0.005). No differences in tumor burden or metastatic burden were observed between runners and non-runners after ten weeks of running when the study was completed. We conclude that voluntary wheel running in PyMT mice correlates with an attenuation in tumor progression early during the course of invasive breast cancer. This effect is absent in the later stages of overwhelming tumor burden even though cytokine signaling for immunosuppressive regulatory T cells was down regulated. These observations suggest that the initiation of moderate exercise training for adjunctive therapeutic benefit early in the course of invasive breast cancer should be considered for further investigation.

Association of prediagnostic physical activity with survival following breast cancer diagnosis: influence of TP53 mutation status

PURPOSE

Physical activity both before and after breast cancer diagnosis has been associated with improved survival. However, it is not clear whether this association differs by molecular features of the tumor or by recency of the physical activity to the time of diagnosis.

METHODS

We examined the association of prediagnostic physical activity with survival in a cohort of 1,170 women with primary, incident, and histologically confirmed breast cancer, examining tumor molecular subtypes. Cox regression models were used to estimate hazard ratios (HR) and 95 % confidence intervals (95 % CI).

RESULTS

Mean follow-up time was 87.4 months after breast cancer diagnosis; there were 170 deaths identified. Compared with inactive patients (<3 h/week), women with higher average lifetime physical activity (>6 h/week) had reduced risk of all-cause mortality (adjusted HR = 0.61, 95 % CI 0.40-0.95; p trend =0.04). There were no clear differences in the associations for lifetime and more recent physical activity. Lifetime physical activity was also weakly associated with decreased risk of breast cancer-specific mortality. Higher lifetime physical activity was associated with reduced risk of all-cause mortality among women with ER-positive tumors (HR = 0.52, 95 % CI 0.29-0.93) and mutant TP53 tumors (HR = 0.22, 95 % CI 0.06-0.72); however, no statistically significant interactions were observed for ER or TP53 status.

CONCLUSIONS

Our study further supports that prediagnostic physical activity improves overall survival following breast cancer and suggests that the associations of prediagnostic physical activity with survival following breast cancer may vary by molecular features of the tumor, particularly ER and TP53 status.

Exercise does not counteract the effects of a "westernized" diet on prostate cancer xenografts

BACKGROUND

The relationships between diet, exercise, and prostate cancer (PCa) remain unclear. We have previously reported that a "Western" diet promotes PCa tumor growth in vivo. Presently, we report the effects of sustained aerobic exercise on PCa progression in animals fed a high-fat diet versus a standard diet.

METHODS

Athymic mice (n = 43) were inoculated subcutaneously with human PCa (LNCaP) cells, fed ad libitum with either a high-fat or a standard diet, and randomized into forced exercising and non-exercising groups. Body weight, tumor volume, and food consumption were recorded tri-weekly. Terminal serum samples and tumor biopsies were obtained for analysis.

RESULTS

Body weight differences were not observed between the groups over time. The high-fat diet with exercise (HF-Ex) group showed significantly increased tumor growth rate compared to all other groups (P < 0.0007). Tumor growth rate of the standard diet with exercise (Std-Ex) group was reduced significantly compared to the high-fat diet without exercise (HF-No Ex) group (P = 0.0008). Significant differences (P ≤ 0.012) were observed in energy consumption (kcal) between the groups over time. Exercising mice consumed significantly more kcal than non-exercising mice, and the HF-Ex group consumed significantly more than each of the other three groups (P < 0.0007). The expression levels of p27 and p21 were increased in exercising animals, while AR expression was elevated in the HF-Ex group versus the Std-Ex and HF-No Ex groups.

CONCLUSIONS

Sustained aerobic exercise did not counteract the tumor-promotional effect of increased consumption of a high-fat diet, suggesting that diet is more influential in PCa progression than exercise. Combining exercise with a healthy diet reduced the rate of PCa progression in this model. This study may have implications for PCa risk reduction in humans.

Modulation of circulating angiogenic factors and tumor biology by aerobic training in breast cancer patients receiving neoadjuvant chemotherapy

Aerobic exercise training (AET) is an effective adjunct therapy to attenuate the adverse side-effects of adjuvant chemotherapy in women with early breast cancer. Whether AET interacts with the antitumor efficacy of chemotherapy has received scant attention. We carried out a pilot study to explore the effects of AET in combination with neoadjuvant doxorubicin-cyclophosphamide (AC+AET), relative to AC alone, on: (i) host physiology [exercise capacity (VO2 peak), brachial artery flow-mediated dilation (BA-FMD)], (ii) host-related circulating factors [circulating endothelial progenitor cells (CEP) cytokines and angiogenic factors (CAF)], and (iii) tumor phenotype [tumor blood flow ((15)O-water PET), tissue markers (hypoxia and proliferation), and gene expression] in 20 women with operable breast cancer. AET consisted of three supervised cycle ergometry sessions/week at 60% to 100% of VO2 peak, 30 to 45 min/session, for 12 weeks. There was significant time × group interactions for VO2 peak and BA-FMD, favoring the AC+AET group (P < 0.001 and P = 0.07, respectively). These changes were accompanied by significant time × group interactions in CEPs and select CAFs [placenta growth factor, interleukin (IL)-1β, and IL-2], also favoring the AC+AET group (P < 0.05). (15)O-water positron emission tomography (PET) imaging revealed a 38% decrease in tumor blood flow in the AC+AET group. There were no differences in any tumor tissue markers (P > 0.05). Whole-genome microarray tumor analysis revealed significant differential modulation of 57 pathways (P < 0.01), including many that converge on NF-κB. Data from this exploratory study provide initial evidence that AET can modulate several host- and tumor-related pathways during standard chemotherapy. The biologic and clinical implications remain to be determined.

Targeting the therapeutic effects of exercise on redox-sensitive mechanisms in the vascular endothelium during tumor progression

The American Cancer Society estimated 1.5 million new cancer cases in the United States in 2012. Although the exact number is not known, it is estimated that brain metastases occur in 20-40% of cancer patients (39). Owing to the complexity of development and the variation in tumor etiology, therapy options have been limited for a number of cancers, whereas progressive treatments have been successful for some malignancies. Combining treatment strategies has shown potential to increase positive outcomes; however, cancer remains a formidable diagnosis with no true cure. Many researchers have focused on alternative forms of cancer prevention or treatment to slow cancer progression. Studies have shown that with moderate, regular exercise signaling pathways associated with increased antioxidant activity and cellular repair are upregulated in vascular tissue; however, the physiological mechanisms are poorly understood. The purpose of this review is to examine the current literature to better understand the impact of exercise on cancer progression and tumor metastasis and discuss potential redox-related signaling in the vasculature that may be involved.

Exercise in the prevention and rehabilitation of breast cancer

Breast cancer is the most common type of cancer among women worldwide. Several epidemiological studies have shown an inverse relationship between the risk of breast cancer and physical activity levels, whereas exercise training has been recognized as a significant means in the rehabilitation process of breast cancer survivors. The relative risk reduction of breast cancer for women who engaged in moderate to vigorous physical activity for 3-5 days peek week ranged between 20-40 %. Furthermore, several studies demonstrated a 24-67 % reduction in the risk of total deaths and 50-53 % reduction in the risk of breast cancer deaths in women who are physically active after breast cancer diagnosis compared with sedentary women. Breast cancer survivors should be encouraged to participate in rehabilitation programs in order to obtain numerous physiological and psychological benefits. These include reductions in fatigue and improvements in immune function, physical functioning, body composition, and quality of life. Based on recent scientific evidence, a complete rehabilitation program for patients with breast cancer should combine both strength and aerobic exercise in order to maximize the expected benefits.

Effects and potential mechanisms of exercise training on cancer progression: a translational perspective

Over the past decade there has been increasing research and clinical interest in the role of exercise therapy/rehabilitation as an adjunct therapy to improve symptom control and management following a cancer diagnosis. More recently, the field of 'exercise - oncology' has broadened in scope to investigate whether the benefits extend beyond symptom control to modulate cancer-specific outcomes (i.e., cancer progression and metastasis). Here we review the extant epidemiological evidence examining the association between exercise behavior, functional capacity/exercise capacity, and cancer-specific recurrence and mortality as well as all-cause mortality individuals following a cancer diagnosis. We also evaluate evidence from clinical studies investigating the effects of structured exercise on blood-based biomarkers associated with cancer progression/metastasis as well findings from preclinical investigations examining the effects and molecular mechanisms of exercise in mouse models of cancer. Current gaps in knowledge are also discussed.

Expression of CXCL14 and its anticancer role in breast cancer

CXCL14, also known as breast and kidney-expressed chemokine, was initially identified as a chemokine highly expressed in the kidney and breast. The exact function of CXCL14 in human breast cancer is still unclear, although it has been testified to play an anti-tumor role in other tumors, including head and neck squamous cell carcinoma, lung cancer, prostate cancer, and so on. In this study, we tried to demonstrate the relationship between CXCL14 and breast cancer. CXCL14 expressions were detected by reverse transcription-PCR and western blot in 2 normal breast epithelial cell lines and 6 breast cancer cell lines. The effects of CXCL14 on the proliferation and invasion in vitro were tested using the CXCL14-overexpressing cells (MDA-MB-231HM-CXCL14) which were established by stable transfection. We established an orthotropic xenograft tumor model in SCID mice using the MDA-MB-231HM-CXCL14 cells and explored the influence of CXCL14 overexpression on tumor growth and metastasis in vivo. Furthermore, we detected the protein level of CXCL14 in 208 breast cancer patients by immunohistochemistry and discussed the correlation between CXCL14 and the prognosis of breast cancer. CXCL14 mRNA expression is lower in breast cancer cell lines, and MDA-MB-231HM express the lowest levels of CXCL14 mRNA. Overexpression of CXCL14 inhibited cell proliferation and invasion in vitro and attenuated xenograft tumor growth and lung metastasis in vivo. CXCL14 protein level is positively correlated to the overall survival of all patients as well as the patients with lymph node metastasis, and it has a negative correlation with the lymph node metastasis. Our study showed for the first time that CXCL14 is a negative regulator of growth and metastasis in breast cancer. The re-expression or up-regulation of this gene may provide a novel strategy in breast cancer therapy in the future.

Muscle-to-organ cross talk mediated by myokines

Cytokines and other peptides are secreted from skeletal muscles in response to exercise and function as hormones either locally within the muscle or by targeting distant organs. Such proteins are recognized as myokines, with the prototype myokine being IL-6. Several studies have established a role of these muscle-derived factors as important contributors of the beneficial effects of exercise, and the myokines are central to our understanding of the cross talk during and after exercise between skeletal muscles and other organs. In a study into the mechanisms of a newly defined myokine, CXCL-1, we found that CXCL-1 overexpression increases muscular fatty acid oxidation with concomitant attenuation of diet-induced fat accumulation in the adipose tissue. Clearly this study adds to the concept of myokines playing an important role in mediating the whole-body adaptive effects of exercise through the regulation of skeletal muscle metabolism. Yet, myokines also contribute to whole-body metabolism by directly signaling to distant organs, regulating metabolic processes in liver and adipose tissue. Thus accumulating data shows that myokines play an important role in restoring a healthy cellular environment, reducing low-grade inflammation and thereby preventing metabolic related diseases like insulin resistance and cancer.

Exercise modulation of the host-tumor interaction in an orthotopic model of murine prostate cancer

The purpose of this study is to investigate the effects of exercise on cancer progression, metastasis, and underlying mechanisms in an orthotopic model of murine prostate cancer. C57BL/6 male mice (6-8 wk of age) were orthotopically injected with transgenic adenocarcinoma of mouse prostate C-1 cells (5 × 10(5)) and randomly assigned to exercise (n = 28) or a non-intervention control (n = 31) groups. The exercise group was given voluntary access to a wheel 24 h/day for the duration of the study. Four mice per group were serially killed on days 14, 31, and 36; the remaining 38 mice (exercise, n = 18; control, n = 20) were killed on day 53. Before death, MRI was performed to assess tumor blood perfusion. Primary tumor growth rate was comparable between groups, but expression of prometastatic genes was significantly modulated in exercising animals with a shift toward reduced metastasis. Exercise was associated with increased activity of protein kinases within the MEK/MAPK and PI3K/mTOR signaling cascades with subsequent increased intratumoral protein levels of HIF-1α and VEGF. This was associated with improved tumor vascularization. Multiplex ELISAs revealed distinct reductions in plasma concentrations of several angiogenic cytokines in the exercise group, which was associated with increased expression of angiogenic and metabolic genes in the skeletal muscle. Exercise-induced stabilization of HIF-1α and subsequent upregulation of VEGF was associated with "productive" tumor vascularization with a shift toward suppressed metastasis in an orthotopic model of prostate cancer.

Calorie restriction and rapamycin inhibit MMTV-Wnt-1 mammary tumor growth in a mouse model of postmenopausal obesity

Obesity is an established risk and progression factor for postmenopausal breast cancer. Interventions to decrease caloric intake and/or increase energy expenditure beneficially impact tumor progression in normoweight humans and animal models. However, despite the increasingly high global prevalence of obesity, the effects and underlying mechanisms of these energy balance modulating interventions are poorly characterized in obese individuals. The goal of this study was to better characterize the mechanism(s) responsible for the link between energy balance and breast cancer progression in the postmenopausal obesity context. We compared the effects of calorie restriction (CR), treadmill exercise (EX), and mammalian target of rapamycin (mTOR inhibitor) treatment on body composition, serum biomarkers, cellular signaling, and mammary tumor growth in obese mice. Ovariectomized C57BL/6 mice were administered a diet-induced obesity regimen for 8 weeks, then randomized into three treatment groups: control (semipurified diet fed ad libitum, maintained the obese state); 30% CR (isonutrient relative to control except 30% reduction in carbohydrate calories); and EX (control diet fed ad libitum plus treadmill exercise). Mice were implanted with syngeneic MMTV-Wnt-1 mammary tumor cells at week 12. Rapamycin treatment (5  mg/kg every 48  h) started at week 14. Tumors were excised at week 18. CR and rapamycin (but not EX) significantly reduced final tumor weight compared to control. In follow-up analysis, constitutive activation of mTOR ablated the inhibitory effects of CR on Wnt-1 mammary tumor growth. We conclude that mTOR inhibition may be a pharmacologic strategy to mimic the anticancer effects of CR and break the obesity-breast cancer progression link.

Peak oxygen consumption and long-term all-cause mortality in nonsmall cell lung cancer

BACKGROUND

Identifying strong markers of prognosis is critical to optimize treatment and survival outcomes in patients with nonsmall cell lung cancer (NSCLC). The authors investigated the prognostic significance of preoperative cardiorespiratory fitness (peak oxygen consumption [VO(2peak)]) among operable candidates with NSCLC.

METHODS

By using a prospective design, 398 patients with potentially resectable NSCLC enrolled in Cancer and Leukemia Group B 9238 were recruited between 1993 and 1998. Participants performed a cardiopulmonary exercise test to assess VO(2peak) and were observed until death or June 2008. Cox proportional models were used to estimate the risk of all-cause mortality according to cardiorespiratory fitness category defined by VO(2peak) tertiles (<0.96 of 0.96-1.29/>1.29 L/min⁻¹) with adjustment for age, sex, and performance status.

RESULTS

Median follow-up was 30.8 months; 294 deaths were reported during this period. Compared with patients achieving a VO(2peak) <0.96 L/min⁻¹, the adjusted hazard ratio (HR) for all-cause mortality was 0.64 (95% confidence interval [CI], 0.46-0.88) for a VO(2peak) of 0.96 to 1.29 L/min⁻¹, and 0.56 (95% CI, 0.39-0.80) for a VO(2peak) of >1.29 L/min⁻¹) (P(trend) = .0037). The corresponding HRs for resected patients were 0.66 (95% CI, 0.46-0.95) and 0.59 (95% CI, 0.40-0.89) relative to the lowest VO(2peak) category (P(trend) = .0247), respectively. For nonresected patients, the HRs were 0.78 (95% CI, 0.34-1.79) and 0.39 (95% CI, 0.16-0.94) relative to the lowest category (P(trend) = .0278).

CONCLUSIONS

VO(2peak) is a strong independent predictor of survival in NSCLC that may complement traditional markers of prognosis to improve risk stratification and prognostication.