Translating energy balance research from the bench to the clinic to the community: Parallel animal-human studies in cancer.

Advances in energy balance and cancer research to date have largely occurred in siloed work in rodents or patients. However, substantial benefit can be derived from parallel studies in which animal models inform the design of clinical and population studies or in which clinical observations become the basis for animal studies. The conference Translating Energy Balance from Bench to Communities: Application of Parallel Animal-Human Studies in Cancer, held in July 2021, convened investigators from basic, translational/clinical, and population science research to share knowledge, examples of successful parallel studies, and strong research to move the field of energy balance and cancer toward practice changes. This review summarizes key topics discussed to advance research on the role of energy balance, including physical activity, body composition, and dietary intake, on cancer development, cancer outcomes, and healthy survivorship.

An ERK5-NRF2 Axis Mediates Senescence-Associated Stemness and Atherosclerosis.

BACKGROUND: ERK5 (extracellular signal-regulated kinase 5) is a dual kinase transcription factor containing an N-terminal kinase domain and a C-terminal transcriptional activation domain. Many ERK5 kinase inhibitors have been developed and tested to treat cancer and inflammatory diseases. However, recent data have raised questions about the role of the catalytic activity of ERK5 in proliferation and inflammation. We aimed to investigate how ERK5 reprograms myeloid cells to the proinflammatory senescent phenotype, subsequently leading to atherosclerosis. METHODS: A ERK5 S496A (dephosphorylation mimic) knock in (KI) mouse model was generated using CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats/clustered regularly interspaced short palindromic repeat-associated 9), and atherosclerosis was characterized by hypercholesterolemia induction. The plaque phenotyping in homozygous ERK5 S496A KI and wild type (WT) mice was studied using imaging mass cytometry. Bone marrow-derived macrophages were isolated from hypercholesterolemic mice and characterized using RNA sequencing and functional in vitro approaches, including senescence, mitochondria reactive oxygen species, and inflammation assays, as well as by metabolic extracellular flux analysis. RESULTS: We show that atherosclerosis was inhibited in ERK5 S496A KI mice. Furthermore, ERK5 S496 phosphorylation mediates both senescence-associated secretory phenotype and senescence-associated stemness by upregulating AHR (aryl hydrocarbon receptor) in plaque and bone marrow-derived macrophages isolated from hypercholesterolemic mice. We also discovered that ERK5 S496 phosphorylation could induce NRF2 (NFE2-related factor 2) SUMOylation at a novel K518 site to inhibit NRF2 transcriptional activity without altering ERK5 catalytic activity and mediates oxidized LDL (low-density lipoprotein)-induced senescence-associated secretory phenotype. Specific ERK5 kinase inhibitors (AX15836 and XMD8-92) also inhibited ERK5 S496 phosphorylation, suggesting the involvement of ERK5 S496 phosphorylation in the anti-inflammatory effects of these ERK5 kinase inhibitors. CONCLUSIONS: We discovered a novel mechanism by which the macrophage ERK5-NRF2 axis develops a unique senescence-associated secretory phenotype/stemness phenotype by upregulating AHR to engender atherogenesis. The finding of senescence-associated stemness phenotype provides a molecular explanation to resolve the paradox of senescence in proliferative plaque by permitting myeloid cells to escape the senescence-induced cell cycle arrest during atherosclerosis formation.

Effects of a Pragmatic Home-based Exercise Program Concurrent With Neoadjuvant Therapy on Physical Function of Patients With Pancreatic Cancer: The PancFit Randomized Clinical Trial.

OBJECTIVE: To determine the effects of a preoperative, home-based exercise program on fitness and physical function in patients with pancreatic cancer. BACKGROUND: We previously established a well-tolerated preoperative exercise program after finding a high frequency of sarcopenia and frailty in patients with pancreatic cancer. METHODS: In this randomized, controlled trial (NCT03187951), patients with pancreatic cancer were randomized to Arm A: enhanced usual care or Arm B: prescribed aerobic and resistance exercise during neoadjuvant therapy. Patients received nutrition counseling and activity trackers. The primary endpoint was a 6-minute walk distance (6MWD; ≥14 meters improvement was clinically meaningful). Secondary endpoints included additional physical function tests, health-related quality of life, and clinical outcomes. RESULTS: One hundred fifty-one patients were randomized. Objectively measured weekly activity (153.2±135.6 and 159.8±122.8 min in Arm A and B, respectively, P =0.62) and self-reported weekly moderate-to-strenuous physical activity (107.4±160.4 and 129.6±161.6 min in Arm A and Arm B, respectively, P =0.49) were similar, but weekly strength training sessions increased more in Arm B (by 1.8±1.8 vs 0.1±2.4 sessions, P <0.001). 6MWD improved in both Arm A (mean change 18.6±56.8 m, P =0.01) and Arm B (27.3±68.1 m, P =0.002). Quality of life and clinical outcomes did not significantly differ between arms. Pooling patients in both study groups, exercise, and physical activity was favorably associated with physical performance and clinical outcomes. CONCLUSIONS: In this randomized trial of prescribed exercise versus enhanced usual care during neoadjuvant therapy for pancreatic cancer, a high volume of physical activity and increased exercise capacity were observed in both arms, highlighting the importance of activity among patients preparing for surgery.

SIRT1 inhibition-induced senescence as a strategy to prevent prostate cancer progression.

Emerging evidence suggests an important role for SIRT1, a nicotinamide adenine dinucleotide (NAD)-dependent deacetylase in cancer development, progression and therapeutic resistance; making it a viable therapeutic target. Here, we examined the impact of resveratrol-mediated pharmacological activation of SIRT1 on the progression of HGPIN lesions (using the Pten-/- mouse model) and on prostate tumor development (using an orthotopic model of prostate cancer cells stably silenced for SIRT1). We show that precise SIRT1 modulation could benefit both cancer prevention and treatment. Positive effect of SIRT1 activation can prevent Pten deletion-driven development of HGPIN lesions in mice if resveratrol is administered early (pre-cancer stage) with little to no benefit after the establishment of HGPIN lesions or tumor cell implantation. Mechanistically, our results show that under androgen deprivation conditions, SIRT1 inhibition induces senescence as evidenced by decreased gene signature associated with negative regulators of senescence and increased senescence-associated ß-galactosidase activity. Furthermore, pharmacological inhibition of SIRT1 potentiated growth inhibitory effects of clinical androgen receptor blockade agents and radiation. Taken together, our findings provide an explanation for the discrepancy regarding the role of SIRT1 in prostate tumorigenesis. Our results reveal that the bifurcated roles for SIRT1 may occur in stage and context-dependent fashion by functioning in an antitumor role in prevention of early-stage prostate lesion development while promoting tumor development and disease progression post-lesion development. Clinically, these data highlight the importance of precise SIRT1 modulation to provide benefits for cancer prevention and treatment including sensitization to conventional therapeutic approaches.

A review of physical activity in pancreatic ductal adenocarcinoma: Epidemiology, intervention, animal models, and clinical trials.

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest types of cancer, and the increasing incidence of PDAC may be related to the prevalence of obesity. Physical activity (PA), a method known to mitigate obesity by increasing total energy expenditure, also modifies multiple cellular pathways associated with cancer hallmarks. Epidemiologic evidence has shown that PA can lower the risk of developing a variety of cancers, reduce some of the detrimental side effects of treatments, and improve patient's quality of life during cancer treatment. However, little is known about the pathways underlying the correlations observed between PA interventions and PDAC. Moreover, there is no standard dose of PA intervention that is ideal for PDAC prevention or as an adjuvant of cancer treatments. In this review, we summarize relevant literature showing how PDAC patients can benefit from PA, the potential of PA as an adjuvant treatment for PDAC, the studies using preclinical models of PDAC to study PA, and the clinical trials to date assessing the effects of PA in PDAC.

Effect of exercise on pancreatic cancer patients during treatment: a scoping review of the literature.

INTRODUCTION: Exercise can lower the risk of developing pancreatic cancer and has the potential to improve physical fitness and quality of life in patients with the disease. Yet, the effects of exercise training during pancreatic cancer treatment remain poorly characterized. This hampers the development of evidence-based disease-specific exercise recommendations. PURPOSE: The purpose of this review was to describe and interpret the effect of exercise on physiological, QoL, and cancer-specific outcomes reported in clinical trials among pancreatic cancer patients during treatment. METHODS: We conducted a scoping review of the literature according to the framework proposed by Arksey and O'Malley. Articles published prior to December 2021 were retrieved from PubMed, EMBASE, and Scopus. We only included studies that prescribed structured cardiorespiratory and/or resistance exercise in pancreatic cancer patients undergoing treatment. RESULTS: A total of 662 references were retrieved, of which 24 are included in the review. Twelve articles were randomized controlled trials and 12 were single-arm trials. Overlap in the trials from which data were reported occurred in 16 articles. Moderate intensity exercise was most commonly prescribed, reported feasible for most patients, with potential to enhance physical fitness and QoL. However, exercise adherence and beneficial effects may diminish with disease progression. Limited evidence suggests exercise may benefit cancer-specific outcomes. CONCLUSION: The results of this review indicate that exercise is feasible during pancreatic cancer treatment. Exercise can also improve physical fitness and QoL. However, its beneficial effects may fall with advanced disease and more rigorous research is needed to develop precise exercise protocols for this population.

Modulating sphingosine-1-phosphate receptors to improve chemotherapy efficacy against Ewing sarcoma.

Tumor vasculature is innately dysfunctional. Poorly functional tumor vessels inefficiently deliver chemotherapy to tumor cells; vessel hyper-permeability promotes chemotherapy delivery primarily to a tumor's periphery. Here, we identify a method for enhancing chemotherapy efficacy in Ewing sarcoma (ES) in mice by modulating tumor vessel permeability. Vessel permeability is partially controlled by the G protein-coupled Sphinosine-1-phosphate receptors 1 and 2 (S1PR1 and S1PR2) on endothelial cells. S1PR1 promotes endothelial cell junction integrity while S1PR2 destabilizes it. We hypothesize that an imbalance of S1PR1:S1PR2 is partially responsible for the dysfunctional vascular phenotype characteristic of ES and that by altering the balance in favor of S1PR1, ES vessel hyper-permeability can be reversed. In our study, we demonstrate that pharmacologic activation of S1PR1 by SEW2871 or inhibition of S1PR2 by JTE-013 caused more organized, mature and functional tumor vessels. Importantly, S1PR1 activation or S1PR2 inhibition improved antitumor efficacy. Our data suggests that pharmacologic targeting of S1PR1 and S1PR2 may be a useful adjuvant to standard chemotherapy for ES patients.

Exercise and Physical Activity in Patients with Osteosarcoma and Survivors.

Exercise has the potential to positively affect patients with osteosarcoma by improvement of function, mitigation of disability, and maintenance of independence and quality of life. Exercise may also directly impact cancer treatment efficacy. This chapter examines the feasibility and use of exercise or physical activity as therapy in the treatment of osteosarcoma and its survivors. It additionally presents the benefits of physical activity as treatment and rehabilitation both preoperatively (prehabilitation) and postoperatively. This chapter will also discuss barriers to exercise and physical activity for patients with osteosarcoma and its survivors, emphasizing the need for a comprehensive and cohesive support system to promote its incorporation into patient treatment plans and ensure compliance.

Vascular modulation through exercise improves chemotherapy efficacy in Ewing sarcoma.

Recent studies in mouse models of cancer have shown that exercise improves tumor vascular function, thereby improving chemotherapy delivery and efficacy. However, the mechanisms underlying this improvement remain unclear and the effect of exercise on Ewing sarcoma (ES), a pediatric bone and soft tissue cancer, is unknown. The effect of exercise on tumor vascular hyperpermeability, which inversely correlates with drug delivery to the tumor, has also not been evaluated. We hypothesized that exercise improves chemotherapy efficacy by enhancing its delivery through improving tumor vascular permeability. We treated ES-bearing mice with doxorubicin with or without moderate treadmill exercise. Exercise did not significantly alter ES tumor vessel morphology. However, compared to control mice, tumors of exercised mice had significantly reduced hyperpermeability, significantly decreased hypoxia, and higher doxorubicin penetration. Compared to doxorubicin alone, doxorubicin plus exercise inhibited tumor growth more efficiently. We evaluated endothelial cell sphingosine-1-phosphate receptors 1 and 2 (S1PR1 and S1PR2) as potential mediators of the improved vascular permeability and increased function afforded by exercise. Relative to tumors from control mice, vessels in tumors from exercised mice had increased S1PR1 and decreased S1PR2 expression. Our results support a model in which exercise remodels ES vasculature to reduce vessel hyperpermeability, potentially via modulation of S1PR1 and S1PR2, thereby improving doxorubicin delivery and inhibiting tumor growth more than doxorubicin alone does. Our data suggest moderate aerobic exercise should be tested in clinical trials as a potentially useful adjuvant to standard chemotherapy for patients with ES.

Physical activity and exercise during preoperative pancreatic cancer treatment.

PURPOSE: Guidelines recommend exercise to cancer survivors, but limited data exists regarding exercise among patients undergoing preoperative cancer treatment. We examined differences in weekly self-reported exercise and accelerometer-measured physical activity among participants in a home-based exercise program administered during preoperative treatment for pancreatic cancer. METHODS: Participants were encouraged to perform at least 60 min/week of moderate-intensity aerobic exercise and at least 60 min/week of full-body strengthening exercises concurrent with chemotherapy, chemoradiation therapy or both sequentially and received resistance equipment, program instruction, and biweekly follow-up calls to encourage adherence. Self-reported aerobic and strengthening exercise minutes were measured using daily logs, and physical activity was measured objectively using accelerometers. RESULTS: Fifty participants (48% female, mean age 66 ± 8 years) participated for an average of 16 ± 9 preoperative weeks. Participants reported overall means of 126 ± 83 weekly minutes of aerobic exercise and 39 ± 33 weekly minutes of strengthening exercise in daily logs. Participants performed 158.7 ± 146.7 weekly minutes of accelerometer-measured moderate-to-vigorous physical activity. There were no significant differences in exercise or physical activity between treatment phases. CONCLUSIONS: These findings suggest that it is feasible to target the entire preoperative course for exercise prescription. Although participants exceeded aerobic exercise recommendations on average, we observed low strengthening exercise adherence and wide variability in self-reported exercise and accelerometer physical activity variables. These findings suggest that additional support, including program adaptations, may be necessary to overcome barriers to exercise or improve motivation when prescribing exercise in this clinical scenario.

Diet and exercise interventions for pediatric cancer patients during therapy: tipping the scales for better outcomes.

Obesity at diagnosis is a negative prognostic indicator for several pediatric cancers including acute leukemia and bone tumors. Incidence of obesity in children has increased three-fold over the past 2 decades, and causes for this include poor diet, excessive caloric intake, and lack of physical activity, which are collectively referred to as energy balance-related behaviors. Few energy balance interventions have been implemented in pediatric cancer patients during treatment, and here we will probe the rationale for pursuing such studies. The need to modify composition of calories consumed and to identify specific beneficial exercise regimens will be discussed, relative to weight reduction or management.

Aerobic Exercise During Early Murine Doxorubicin Exposure Mitigates Cardiac Toxicity.

We report the cardioprotective effects of moderate aerobic exercise from parallel pediatric murine models of doxorubicin (Doxo) exposure in non-tumor-bearing immune competent (NTB-IC) mice and tumor-bearing nude mice (TB-NM). In both models, animals at 4 weeks of age underwent Doxo treatment with or without 2 weeks of simultaneous exercise. In sedentary NTB-IC or TB-NM mice, Doxo treatment resulted in a statistically significant decrease in ejection fraction and fractional shortening compared with control animals. Interestingly, moderate aerobic exercise during Doxo treatment significantly mitigated decreases in ejection fraction and fractional shortening. In contrast, these protective effects of exercise were not observed when exercise was started after completion of Doxo treatments. Moreover, in the TB-NM model, Doxo caused a decrease in heart mass: tibia length and in body weight that was prevented by exercise, whereas NTB-IC mice exhibited no change in these measurements. Doxo delivery to the hearts of TB-NM was decreased by consistent moderate aerobic exercise before Doxo injection. These findings demonstrate the important but subtle differences in cardiotoxicity observed in different mouse models. Collectively, these results also strongly suggest that aerobic exercise during early-life Doxo exposure mitigates cardiotoxicity, possibly through altered delivery of Doxo to myocardial tissue.

Hes4: A potential prognostic biomarker for newly diagnosed patients with high-grade osteosarcoma.

BACKGROUND: Prognostic biomarkers for osteosarcoma (OS) at the time of diagnosis are lacking. Necrotic response of OS to preoperative chemotherapy correlates with survival and is determined 3-4 months after diagnosis. The purpose of this study is to identify biomarkers that will stratify patients into good or poor responders to chemotherapy at diagnosis and determine the role of potential biomarkers in OS pathogenesis. PROCEDURE: Because OS may be caused by disruptions of osteogenic differentiation, and the Notch pathway is one regulator of bone development, we examined the link between Notch effectors, OS differentiation, and OS outcome. We probed the R2: Genomics Analysis and Visualization Platform for RNA expression levels of Notch targets in mixed high-grade OS pretreatment biopsies. We used human OS cell lines in vitro and in mice to determine the role of the Notch target hairy/enhancer of split 4 (Hes4) in OS. RESULTS: We found that in OS patients, high expression of Hes4 is correlated with decreased metastasis-free and overall survival. Human OS cells that overexpress Hes4 are more immature and have an increased invasive capacity in vitro. This was not universal to all Notch effectors, as Hes1 overexpression induced opposing effects. When injected into NSG mice, Hes4-overexpressing OS cells produced significantly larger, more lytic tumors and significantly more metastases than did control cells. CONCLUSIONS: Hes4 overexpression promotes a more aggressive tumor phenotype by preventing osteoblastic differentiation of OS cells. Hes4 expression may allow for the stratification of patients into good or poor responders to chemotherapy at diagnosis.

Home-based exercise during preoperative therapy for pancreatic cancer.

PURPOSE: Exercise concurrent with neoadjuvant chemotherapy and/or chemoradiation for pancreatic adenocarcinoma (PDAC) may mitigate the decline in function that may occur as a result of the disease or its treatment in the preoperative period. The primary objective of this single-arm prospective trial was to determine adherence to a home-based exercise program administered during preoperative therapy. METHODS: Twenty patients from a quaternary cancer center with potentially resectable PDAC were enrolled. Patients were prescribed a minimum of 120 min of moderate-intensity exercise weekly: at least 60 min of aerobic exercise and 60 min of resistance exercise. Self-reported exercise was recorded in daily logs. Functional and survey measures were collected upon enrollment, following preoperative therapy, and 1 month after surgery. RESULTS: Fifteen out of 20 patients participated in the program. They reported a mean (standard deviation (SD)) of 98.6 (69.8) min of aerobic exercise weekly and 57.4 (36.0) min of strengthening exercise weekly over a median of 17 weeks (range, 5-35 weeks) of preoperative therapy, for a mean (SD) of 156.0 (64.5) min of total exercise weekly. Eighty percent reported a mean of least 120 min of total exercise weekly during preoperative therapy. Patients with low baseline physical activity based on the International Physical Activity Questionnaire significantly increased their preoperative physical activity (p = .01). There were no adverse events associated with the exercise program. CONCLUSIONS: Patients with PDAC will participate in a home-based exercise program of aerobic and strengthening exercise and will increase physical activity, concurrent with preoperative chemotherapy and/or chemoradiation.

Genome-wide approaches reveal functional vascular endothelial growth factor (VEGF)-inducible nuclear factor of activated T cells (NFAT) c1 binding to angiogenesis-related genes in the endothelium.

VEGF is a key regulator of endothelial cell migration, proliferation, and inflammation, which leads to activation of several signaling cascades, including the calcineurin-nuclear factor of activated T cells (NFAT) pathway. NFAT is not only important for immune responses but also for cardiovascular development and the pathogenesis of Down syndrome. By using Down syndrome model mice and clinical patient samples, we showed recently that the VEGF-calcineurin-NFAT signaling axis regulates tumor angiogenesis and tumor metastasis. However, the connection between genome-wide views of NFAT-mediated gene regulation and downstream gene function in the endothelium has not been studied extensively. Here we performed comprehensive mapping of genome-wide NFATc1 binding in VEGF-stimulated primary cultured endothelial cells and elucidated the functional consequences of VEGF-NFATc1-mediated phenotypic changes. A comparison of the NFATc1 ChIP sequence profile and epigenetic histone marks revealed that predominant NFATc1-occupied peaks overlapped with promoter-associated histone marks. Moreover, we identified two novel NFATc1 regulated genes, CXCR7 and RND1. CXCR7 knockdown abrogated SDF-1- and VEGF-mediated cell migration and tube formation. siRNA treatment of RND1 impaired vascular barrier function, caused RhoA hyperactivation, and further stimulated VEGF-mediated vascular outgrowth from aortic rings. Taken together, these findings suggest that dynamic NFATc1 binding to target genes is critical for VEGF-mediated endothelial cell activation. CXCR7 and RND1 are NFATc1 target genes with multiple functions, including regulation of cell migration, tube formation, and barrier formation in endothelial cells.

The calcineurin-NFAT pathway negatively regulates megakaryopoiesis.

The calcium regulated calcineurin-nuclear factor of activated T cells (NFAT) pathway modulates the physiology of numerous cell types, including hematopoietic. Upon activation, calcineurin dephosphorylates NFAT family transcription factors, triggering their nuclear entry and activation or repression of target genes. NFATc1 and c2 isoforms are expressed in megakaryocytes. Moreover, human chromosome 21 (Hsa21) encodes several negative regulators of calcineurin-NFAT, candidates in the pathogenesis of Down syndrome (trisomy 21)-associated transient myeloproliferative disorder and acute megakaryoblastic leukemia. To investigate the role of calcineurin-NFAT in megakaryopoiesis, we examined wild-type mice treated with the calcineurin inhibitor cyclosporin A and transgenic mice expressing a targeted single extra copy of Dscr1, an Hsa21-encoded calcineurin inhibitor. Both murine models exhibited thrombocytosis with increased megakaryocytes and megakaryocyte progenitors. Pharmacological or genetic inhibition of calcineurin in mice caused accumulation of megakaryocytes exhibiting enhanced 5-bromo-2'-deoxyuridine uptake and increased expression of messenger RNAs encoding CDK4 and G1 cyclins, which promote cell division. Additionally, human megakaryocytes with trisomy 21 show increased proliferation and decreased NFAT activation compared with euploid controls. Our data indicate that inhibition of calcineurin-NFAT drives proliferation of megakaryocyte precursors by de-repressing genes that drive cell division, providing insights into mechanisms of normal megakaryopoiesis and megakaryocytic abnormalities that accompany Down syndrome.

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, ß-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.

Aerobic Exercise Alters the Melanoma Microenvironment and Modulates ERK5 S496 Phosphorylation.

Exercise changes the tumor microenvironment by remodeling blood vessels and increasing infiltration by cytotoxic immune cells. The mechanisms driving these changes remain unclear. Herein, we demonstrate that exercise normalizes tumor vasculature and upregulates endothelial expression of VCAM1 in YUMMER 1.7 and B16F10 murine models of melanoma but differentially regulates tumor growth, hypoxia, and the immune response. We found that exercise suppressed tumor growth and increased CD8+ T-cell infiltration in YUMMER but not in B16F10 tumors. Single-cell RNA sequencing and flow cytometry revealed exercise modulated the number and phenotype of tumor-infiltrating CD8+ T cells and myeloid cells. Specifically, exercise caused a phenotypic shift in the tumor-associated macrophage population and increased the expression of MHC class II transcripts. We further demonstrated that ERK5 S496A knock-in mice, which are phosphorylation deficient at the S496 residue, "mimicked" the exercise effect when unexercised, yet when exercised, these mice displayed a reversal in the effect of exercise on tumor growth and macrophage polarization compared with wild-type mice. Taken together, our results reveal tumor-specific differences in the immune response to exercise and show that ERK5 signaling via the S496 residue plays a crucial role in exercise-induced tumor microenvironment changes. See related Spotlight by Betof Warner, p. 1158.

Comparison of three exercise interventions with and without gemcitabine treatment on pancreatic tumor growth in mice: No impact on tumor infiltrating lymphocytes.

Exercise has been shown to slow pancreatic tumor growth, but whether exercise interventions of differing volume or intensity yield differential effects on tumor outcomes is unknown. In this study, we compared three exercise training interventions implemented with and without chemotherapy on pancreatic tumor growth in mice. Methods: Male C57BL/6 mice (6-8 weeks old) were subcutaneously inoculated with pancreatic ductal adenocarcinoma tumor cells (PDAC 4662). Upon tumor detection, mice received gemcitabine 15 mg/kg intraperitoneally 3 days/week and were assigned to exercise: high volume continuous exercise (HVCE), low volume continuous exercise (LVCE), high intensity interval training (HIIT), or sedentary (SED). HVCE ran at 12 m/min for 45 min and LVCE for 15 min, 5 days/week. HIIT ran 1-min at 20 m/min, followed by 1-min walking at 8 m/min for 20 total intervals, 3 days/week. SED did not run. Additional sets of inoculated mice were assigned to the exercise interventions but did not receive gemcitabine. Tumor volume was measured every other day for 2 weeks; tumor-infiltrating lymphocytes were assessed by flow cytometry 3-week post-inoculation. Results: Tumor growth did not differ between groups that received gemcitabine (F(3, 34) = 1.487; p = 0.235; η2 = 0.116). In contrast, tumor growth differed between groups not provided gemcitabine (F(3,14) = 3.364; p = 0.049, η2 = 0.419), with trends for slower growth in LVCE than SED (p = 0.088) and HIIT (p = 0.084). Groups did not differ in tumor infiltrating lymphocytes. Conclusion: Contrary to our hypotheses, the exercise interventions compared here did not further reduce pancreatic tumor growth beyond that provided by gemcitabine. However, in mice not receiving gemcitabine, there was a trend for reduced tumor growth in LVCE.

Exercise Promotes Pro-Apoptotic Ceramide Signaling in a Mouse Melanoma Model.

Ceramides are essential sphingolipids that mediate cell death and survival. Low ceramide content in melanoma is one mechanism of drug resistance. Thus, increasing the ceramide content in tumor cells is likely to increase their sensitivity to cytotoxic therapy. Aerobic exercise has been shown to modulate ceramide metabolism in healthy tissue, but the relationship between exercise and ceramide in tumors has not been evaluated. Here, we demonstrate that aerobic exercise causes tumor cell apoptosis and accumulation of pro-apoptotic ceramides in B16F10 but not BP melanoma models using mice. B16F10 tumor-bearing mice were treated with two weeks of moderate treadmill exercise, or were control, unexercised mice. A reverse-phase protein array was used to identify canonical p53 apoptotic signaling as a key pathway upregulated by exercise, and we demonstrate increased apoptosis in tumors from exercised mice. Consistent with this finding, pro-apoptotic C16-ceramide, and the ceramide generating enzyme ceramide synthase 6 (CerS6), were higher in B16F10 tumors from exercised mice, while pro-survival sphingosine kinase 1 (Sphk1) was lower. These data suggest that exercise contributes to B16F10 tumor cell death, possibly by modulating ceramide metabolism toward a pro-apoptotic ceramide/sphingosine-1-phosphate balance. However, these results are not consistent in BP tumors, demonstrating that exercise can have different effects on tumors of different patient or mouse origin with the same diagnosis. This work indicates that exercise might be most effective as a therapeutic adjuvant with therapies that kill tumor cells in a ceramide-dependent manner.