Aerobic Exercise Training Attenuates Tumor Growth and Reduces Insulin Secretion in Walker 256 Tumor-Bearing Rats

Moderate-intensity continuous training reduces triglyceridemia and improves oxygen consumption in dyslipidemic apoCIII transgenic mice

This study aimed to investigate metabolism modulation and dyslipidemia in genetic dyslipidemic mice through physical exercise. Thirty-four male C57Bl/6 mice aged 15 months were divided into non-transgenic (NTG) and transgenic overexpressing apoCIII (CIII) groups. After treadmill adaptation, the trained groups (NTG Ex and CIII Ex) underwent an effort test to determine running performance and assess oxygen consumption (V̇O2), before and after the training protocol. The exercised groups went through an 8-week moderate-intensity continuous training (MICT) program, consisting of 40 min of treadmill running at 60% of the peak velocity achieved in the test, three times per week. At the end of the training, animals were euthanized, and tissue samples were collected for ex vivo analysis. ApoCIII overexpression led to hypertriglyceridemia (P<0.0001) and higher concentrations of total plasma cholesterol (P<0.05), low-density lipoprotein (LDL) cholesterol (P<0.01), and very low-density lipoprotein (VLDL) cholesterol (P<0.0001) in the animals. Furthermore, the transgenic mice exhibited increased adipose mass (P<0.05) and higher V̇O2peak compared to their NTG controls (P<0.0001). Following the exercise protocol, MICT decreased triglyceridemia and cholesterol levels in dyslipidemic animals (P<0.05), and reduced adipocyte size (P<0.05), increased muscular glycogen (P<0.001), and improved V̇O2 in all trained animals (P<0.0001). These findings contribute to our understanding of the effects of moderate and continuous exercise training, a feasible non-pharmacological intervention, on the metabolic profile of genetically dyslipidemic subjects.

Cancer Cachexia: Underlying Mechanisms and Potential Therapeutic Interventions

Cancer cachexia, a multifactorial metabolic syndrome developed during malignant tumor growth, is characterized by an accelerated loss of body weight accompanied by the depletion of skeletal muscle mass. This debilitating condition is associated with muscle degradation, impaired immune function, reduced functional capacity, compromised quality of life, and diminished survival in cancer patients. Despite the lack of the known capability of fully reversing or ameliorating this condition, ongoing research is shedding light on promising preclinical approaches that target the disrupted mechanisms in the pathophysiology of cancer cachexia. This comprehensive review delves into critical aspects of cancer cachexia, including its underlying pathophysiological mechanisms, preclinical models for studying the progression of cancer cachexia, methods for clinical assessment, relevant biomarkers, and potential therapeutic strategies. These discussions collectively aim to contribute to the evolving foundation for effective, multifaceted counteractive strategies against this challenging condition.

Exercise Is Medicine: How Do We Implement It?

Exercise is well known to have beneficial effects on various disease states. In this paper, we broadly describe the fundamental concepts that are shared among various disease states, including obesity, type 2 diabetes (T2D), cardiovascular disease (CVD), heart failure (HF), cancer, and psychological well-being, and the beneficial effects of exercise training within these concepts. We highlight issues involved in implementing exercise recommendations and describe the potential impacts and challenges to medical professionals and patients. Problems are identified and discussed with respect to the future roles of professionals in the current built environment with its limited infrastructure to support current physical activity recommendations.

Targeting cancer cachexia: Molecular mechanisms and clinical study

Cancer cachexia is a complex systemic catabolism syndrome characterized by muscle wasting. It affects multiple distant organs and their crosstalk with cancer constitute cancer cachexia environment. During the occurrence and progression of cancer cachexia, interactions of aberrant organs with cancer cells or other organs in a cancer cachexia environment initiate a cascade of stress reactions and destroy multiple organs including the liver, heart, pancreas, intestine, brain, bone, and spleen in metabolism, neural, and immune homeostasis. The role of involved organs turned from inhibiting tumor growth into promoting cancer cachexia in cancer progression. In this review, we depicted the complicated relationship of cancer cachexia with the metabolism, neural, and immune homeostasis imbalance in multiple organs in a cancer cachexia environment and summarized the treatment progress in recent years. And we discussed the molecular mechanism and clinical study of cancer cachexia from the perspective of multiple organs metabolic, neurological, and immunological abnormalities. Updated understanding of cancer cachexia might facilitate the exploration of biomarkers and novel therapeutic targets of cancer cachexia.

Molecular Mechanisms and Current Treatment Options for Cancer Cachexia

Simple Summary

The primary characteristics of cancer cachexia are weakness, weight loss, atrophy, fat reduction, and systemic inflammation. Cachexia is strongly associated with cancers involving the lungs, pancreas, esophagus, stomach, and liver, which account for half of all cancer deaths. TGF-β, MSTN, activin, IGF-1/PI3K/AKT, and JAK-STAT signaling pathways are known to underlie muscle atrophy and cachexia. Anamorelin (appetite stimulation), megestrol acetate, eicosapentaenoic acid, phytocannabinoids, targeting MSTN/activin, and molecules targeting proinflammatory cytokines, such as TNF-α and IL-6, are being tested as treatment options for cancer cachexia.

Abstract

Cancer cachexia is a condition marked by functional, metabolic, and immunological dysfunctions associated with skeletal muscle (SM) atrophy, adipose tissue loss, fat reduction, systemic inflammation, and anorexia. Generally, the condition is caused by a variety of mediators produced by cancer cells and cells in tumor microenvironments. Myostatin and activin signaling, IGF-1/PI3K/AKT signaling, and JAK-STAT signaling are known to play roles in cachexia, and thus, these pathways are considered potential therapeutic targets. This review discusses the current state of knowledge of the molecular mechanisms underlying cachexia and the available therapeutic options and was undertaken to increase understanding of the various factors/pathways/mediators involved and to identify potential treatment options.

Nutritional and Exercise Interventions in Cancer-Related Cachexia: An Extensive Narrative Review

One of the common traits found in cancer patients is malnutrition and cachexia, which affects between 25% to 60% of the patients, depending on the type of cancer, diagnosis, and treatment. Given the lack of current effective pharmacological solutions for low muscle mass and sarcopenia, holistic interventions are essential to patient care, as well as exercise and nutrition. Thus, the present narrative review aimed to analyze the nutritional, pharmacological, ergonutritional, and physical exercise strategies in cancer-related cachexia. The integration of multidisciplinary interventions could help to improve the final intervention in patients, improving their prognosis, quality of life, and life expectancy. To reach these aims, an extensive narrative review was conducted. The databases used were MedLine (PubMed), Cochrane (Wiley), Embase, PsychINFO, and CinAhl. Cancer-related cachexia is a complex multifactorial phenomenon in which systemic inflammation plays a key role in the development and maintenance of the symptomatology. Pharmacological interventions seem to produce a positive effect on inflammatory state and cachexia. Nutritional interventions are focused on a high-energy diet with high-density foods and the supplementation with antioxidants, while physical activity is focused on strength-based training. The implementation of multidisciplinary non-pharmacological interventions in cancer-related cachexia could be an important tool to improve traditional treatments and improve patients' quality of life.

Exercise in People With Cancer: A Spotlight on Energy Regulation and Cachexia

Exercise is increasingly becoming a standard of cancer care, with well-documented benefits for patients including improved mental wellbeing and reduced treatment-related side effects. However, important gaps in knowledge remain about how to optimise exercise prescription for people with cancer. Importantly, it remains unclear how exercise affects the progression of cancer cachexia (a wasting disease stemming from energy imbalance, and a common manifestation of advanced malignant disease), particularly once the condition has already developed. It was recently suggested that the anti-tumour effect of exercise might come from improved energetic capacity. Here, we highlight the possible effect of exercise on energetic capacity and energy regulation in the context of cancer, and how this might affect the progression of cancer cachexia. We suggest that due to the additional energy demand caused by the tumour and associated systemic inflammation, overreaching may occur more easily in people with cancer. Importantly, this could result in impaired anti-tumour immunity and/or the exacerbation of cancer cachexia. This highlights the importance of individualised exercise programs for people with cancer, with special consideration for the regulation of energy balance, ongoing monitoring and possible nutritional supplementation to support the increased energy demand caused by exercise.

Multiple Applications of Different Exercise Modalities with Rodents

A large proportion of chronic diseases can be derived from a sedentary lifestyle. Raising physical activity awareness is indispensable, as lack of exercise is the fourth most common cause of death worldwide. Animal models in different research fields serve as important tools in the study of acute or chronic noncommunicable disorders. With the help of animal-based exercise research, exercise-mediated complex antioxidant and inflammatory pathways can be explored, which knowledge can be transferred to human studies. Whereas sustained physical activity has an enormous number of beneficial effects on many organ systems, these animal models are easily applicable in several research areas. This review is aimed at providing an overall picture of scientific research studies using animal models with a focus on different training modalities. Without wishing to be exhaustive, the most commonly used forms of exercise are presented.

Moderate endurance training reduced hepatic tumourigenesis associated with lower lactate overload compared to high-intensity interval training

The anti-tumour effects of exercise are still poorly understood. In recent years, high-intensity interval exercise has been recognised as one of the best choices for better health. However, high-intensity interval exercise induces lactate production in muscles and elevates blood lactic acid levels, and the resulting acidic microenvironment may promote tumour progression. Therefore, it is important to compare the anti-tumour effects of different types of exercise.

OBJECTIVE

In this study, we aimed to compare the anti-tumour effects of moderate endurance training and high-intensity interval training on diethylnitrosamine (DEN)-induced liver tumours and to explore the underlying mechanisms.

METHODS

Three-week-old male C57BL/6 mice were injected intraperitoneally with DEN for 10 weeks to induce hepatocellular carcinoma. DEN-treated mice were grouped and subjected to moderate endurance training (MET) or high-intensity interval training (HIIT) for 18 weeks. We performed real-time PCR to evaluate the mRNA expressions of key enzymes involved in lactate metabolism pathway and western blotting to examine the protein expressions of LDHA, AMPK/P-AMPK, PCK1, and G6Pase in the paracancerous liver tissue. We performed high-performance liquid mass spectrometry (HPLC) to detect lactate in liver.

RESULTS

Our results revealed that compared with HIIT, MET decreased hepatic tumour incidence, as HIIT increased blood lactate concentration at rest. Moreover, MET reduced the transcript-level expression of LDH subunit and significantly increased the mRNA levels of COX1 and ND1 in liver. However, no significant changes were observed in liver lactate levels and the expression of LDHA among the groups. In addition, no significant differences in the mRNA levels of critical enzymes involved in the gluconeogenesis pathway in liver were observed among the groups. Additionally, no significant differences were observed in the mRNA levels of MPC2, pdha2, and pdk4 among the groups.

CONCLUSIONS

Our findings suggest that MET may be more efficient than HIIT at reducing hepatic tumourigenesis, and that it is associated with improved mitochondrial function in liver and lower lactate load in the circulation at rest.

Can Exercise Counteract Cancer Cachexia? A Systematic Literature Review and Meta-Analysis

Background:

Cancer-cachexia is associated with chronic inflammation, impaired muscle metabolism and body mass loss, all of which are classical targets of physical exercise.

Objectives:

This systematic review and meta-analysis aimed to determine the effects of exercise on body and muscle mass in cachectic cancer hosts.

Data Sources:

PubMed/Medline, EMBASE, CINHAL, ISI Web of Science, and Cochrane Library were searched until July 2019.

Study Selection:

Trials had to be randomized controlled trials or controlled trials including cancer patients or animal models with cachexia-inducing tumors. Only sole exercise interventions over at least 7 days performed in a controlled environment were included.

Data Extraction:

Risk of bias was assessed and a random-effects model was used to pool effect sizes by standardized mean differences (SMD).

Results:

All eligible 20 studies were performed in rodents. Studies prescribed aerobic (n = 15), strength (n = 3) or combined training (n = 2). No statistical differences were observed for body mass and muscle weight of the gastrocnemius, soleus, and tibialis muscles between the exercise and control conditions (SMD = ‒0.05, 95%CI-0.64-0.55, P = 0.87). Exercise duration prior to tumor inoculation was a statistical moderator for changes in body mass under tumor presence (P = 0.04).

Limitations:

No human trials were identified. A large study heterogeneity was present, probably due to different exercise modalities and outcome reporting.

Conclusion:

Exercise does not seem to affect cancer-cachexia in rodents. However, the linear regression revealed that exercise duration prior to tumor inoculation led to reduced cachexia-severity, possibly strengthening the rationale for the use of exercise in cancer patients at cachexia risk.

Early postnatal overnutrition impairs VO2max gains with moderate exercise and increase post-exercise muscle damage in adult male rats

Exercise counteracts obesity effects, but information on how early-life obesity may affect long-term adaptation to exercise is lacking. This study investigates the impact of early-life postnatal overfeeding (PO) on animals' adaptation to exercise. Only male Wistar rats were used. On postnatal day (PN) 30, rats from control (NL-9 pups) or PO (SL-3 pups) litters were separated into four groups: NL-sedentary (NL-Se), NL-exercised (NL-Ex), SL-sedentary (SL-Se), and SL-exercised (SL-Ex). Exercised groups performed moderate-intensity exercise, running on a treadmill, from PN30 to PN90. Further experiments were carried out between PN90 and PN92. PO promoted obesity in SL versus NL rats (P < 0.05). Exercise reduced body weight (P < 0.001), body fat (P < 0.01), and improved glucose homeostasis in SL-Ex versus SL-Se. SL-Ex presented lower VO2max (P < 0.01) and higher post-exercise LDH (P < 0.05) compared to NL-Ex rats. Although moderate exercise counteracted obesity in SL rats, early-life overnutrition restricts fitness gains in adulthood, indicating that early obesity may impair animals' adaptation to exercise.

Suppressing breast cancer by exercise: consideration to animal models and exercise protocols

PURPOSE

Exercise is thought to have a significant effect on chemotherapy, and previous studies have reported that exercise can increase patient survival. Thus, in this review, we aimed to summarize various animal models to analyze the effects of exercise on breast cancer.

METHODS

We summarized types of breast cancer animal models from various reports and analyzed the effects of exercise on anti-cancer factors in breast cancer animal models.

RESULTS

This review aimed to systematically investigate if exercise could aid in suppressing breast cancer. Our study includes (a) increase in survival rate through exercise; (b) the intensity of exercise should be consistent and increased; (c) a mechanism for inhibiting carcinogenesis through exercise; (d) effects of exercise on anti-cancer function.

CONCLUSION

This review suggested the necessity of a variety of animal models for preclinical studies prior to breast cancer clinical trials. It also provides evidence to support the view that exercise plays an important role in the prevention or treatment of breast cancer by influencing anticancer factors.

Endurance training but not high-intensity interval training reduces liver carcinogenesis in mice with hepatocellular carcinogen diethylnitrosamine

Physical activity may reduce cancer initiation. High-intensity interval training (HIT) has been reported to be superior to moderate continuous endurance training (ET) for maximizing health outcomes in cardiovascular disease, obesity and type 2 diabetes. However, the role of HIT vs. ET in the prevention of liver cancer is poorly understood. This study aimed to determine how HIT vs. ET affects cancer initiation in mice with the hepatocellular carcinogen diethylnitrosamine (DEN). C57BL/6 mice were treated with DEN at 3-12 weeks of age and, from 8 to 26 weeks of age, treated with either of exercise modes on treadmill: HIT (85-90% VO2max with intervals) and ET (65-75% VO2max without intervals). We found that mice treated with ET had lower cancer initiation but higher fat mass compared to control DEN-injected mice. In contrast, HIT could not significantly reduce cancer initiation and tumor volumes. Metabolomic analysis in the liver indicated marked differences in cholesterol, palmitic acid, stearic acid, uracil, hydroxypyridine and maltose between HIT- and ET-treated mice, and demonstrated good and obvious separation between ET and DEN control group. Furthermore, mice treated with ET had lower expression of pro-inflammatory cytokines and pro-proliferation genes in liver compared to DEN control group. ET protocol reduced the accumulation of toxic metabolite carbamate, increased the protein level of caspase-1, and reduced JNK phosphorylation in liver. These data indicates that moderate-intensity endurance training may be superior to high-intensity interval training for reducing liver cancer initiation in mice.

Effects of Exercise on the Tumour Microenvironment

Epidemiological evidence suggests that exercise improves survival in cancer patients. However, much is still unknown regarding the mechanisms of this positive survival effect and there are indications that exercise may not be universally beneficial for cancer patients. The key to understanding in which situations exercise is beneficial may lie in understanding its influence on the tumour microenvironment (TME)-and conversely, the influence of the tumour on physical functioning. The TME consists of a vast multitude of different cell types, mechanical and chemical stressors and humoral factors. The interplay of these different components greatly influences tumour cell characteristics and, subsequently, tumour growth rate and aggression. Exercise exerts whole-body physiological effects and can directly and indirectly affect the TME. In this chapter, we first discuss the possible role of exercise capacity ('fitness') and exercise adaptability on tumour responsiveness to exercise. We summarise how exercise affects aspects of the TME such as tumour perfusion, vascularity, hypoxia (reduced oxygenation) and immunity. Additionally, we discuss the role of myokines and other circulating factors in eliciting these changes in the TME. Finally, we highlight unanswered questions and key areas for future research in exercise oncology and the TME.

Moderate exercise training since adolescence reduces Walker 256 tumour growth in adult rats

KEY POINTS

Cancer growth, cell proliferation and cachexia index can be attenuated by the beneficial programming effect of moderate exercise training, especially if it begins in adolescence. Walker 256 tumour-bearing rats who started exercise training during adolescence did not revert the basal low glycaemia and insulinaemia observed before tumour cell inoculation. The moderate exercise training improved glucose tolerance and peripheral insulin sensitivity only in rats exercised early in adolescence. The chronic effects of our exercise protocol are be beneficial to prevent cancer cachexia and hold clear potential as a nonpharmacological therapy of insulin sensitization.

ABSTRACT

We tested the hypothesis that moderate exercise training, performed early, starting during adolescence or later in life during adulthood, can inhibit tumour cell growth as a result of changes in biometric and metabolic markers. Male rats that were 30 and 70 days old performed a treadmill running protocol over 8 weeks for 3 days week^-1 , 44 min day^-1 and at 55-65% V ̇ O 2 max . After the end of training, a batch of rats was inoculated with Walker 256 carcinoma cells. At 15 days after carcinoma cell inoculation, the tumour was weighed and certain metabolic parameters were evaluated. The data demonstrated that physical performance was better in rats that started exercise training during adolescence according to the final workload and V ̇ O 2 max . Early or later moderate exercise training decreased the cachexia index, cell proliferation and tumour growth; however, the effects were more pronounced in rats that exercised during adolescence. Low glycaemia, insulinaemia and tissue insulin sensitivity was not reverted in Walker 256 tumour-bearing rats who trained during adolescence. Cancer growth can be attenuated by the beneficial programming effect of moderate exercise training, especially if it begins during adolescence. In addition, improvement in glucose-insulin homeostasis might be involved in this process.