Chemotherapy-Induced Molecular Changes in Skeletal Muscle

Cancer-associated muscle weakness - From triggers to molecular mechanisms

Skeletal muscle weakness is a debilitating consequence of many malignancies. Muscle weakness has a negative impact on both patient wellbeing and outcome in a range of cancer types and can be the result of loss of muscle mass (i.e. muscle atrophy, cachexia) and occur independently of muscle atrophy or cachexia. There are multiple cancer specific triggers that can initiate the progression of muscle weakness, including the malignancy itself and the tumour environment, as well as chemotherapy, radiotherapy and malnutrition. This can induce weakness via different routes: 1) impaired intrinsic capacity (i.e., contractile dysfunction and intramuscular impairments in excitation-contraction coupling or crossbridge cycling), 2) neuromuscular disconnection and/or 3) muscle atrophy. The mechanisms that underlie these pathways are a complex interplay of inflammation, autophagy, disrupted protein synthesis/degradation, and mitochondrial dysfunction. The current lack of therapies to treat cancer-associated muscle weakness highlight the critical need for novel interventions (both pharmacological and non-pharmacological) and mechanistic insight. Moreover, most research in the field has placed emphasis on directly improving muscle mass to improve muscle strength. However, accumulating evidence suggests that loss of muscle function precedes atrophy. This review primarily focuses on cancer-associated muscle weakness, independent of cachexia, and provides a solid background on the underlying mechanisms, methodology, current interventions, gaps in knowledge, and limitations of research in the field. Moreover, we have performed a mini-systematic review of recent research into the mechanisms behind muscle weakness in specific cancer types, along with the main pathways implicated.

Prevalence and clinical outcomes of sarcopenia in patients with esophageal, gastric or colorectal cancers receiving preoperative neoadjuvant therapy: A meta-analysis

Objective

To investigate the prevalence of sarcopenia and its impact on clinical outcomes in patients with esophageal, gastric, or colorectal cancer (EC, GC, and CRC) receiving neoadjuvant therapy through Meta-analysis.

Methods

We searched the PubMed, Embase databases, and Cochrane Library for the prevalence of sarcopenia and its impact on clinical outcomes in EC, GC, or CRC patients treated with neoadjuvant therapy (NAT) from inception to November 2022. The primary endpoints were the prevalence of sarcopenia and overall survival in patients with EC, GC, or CRC treated with NAT. Secondary outcomes included recurrence-free survival, total postoperative complications, grade 3-4 chemotherapy toxicity, and 30-day mortality after surgery.

Results

Thirty-one retrospective studies with 3651 subjects were included. In a fixed-effects model, the prevalence of muscle loss was higher in patients with EC, GC, or CRC at 50% (95% CI ​= ​42% to 58%). The results of the multivariate analysis showed that preoperative patients with sarcopenia had a 1.91 times shorter overall survival (95% CI ​= ​1.61-2.27) and a 1.77 times shorter recurrence-free survival time (95% CI ​= ​1.33-2.35) than patients without sarcopenia, and that patients with sarcopenia had a higher risk of total postoperative complications than patients without sarcopenia OR ​= ​1.27 (95% CI ​= ​1.03-1.57). However, the two groups had no statistical difference in grade 3-4 chemotherapy toxicity (P ​= ​0.84) or 30-d postoperative mortality (P ​= ​0.88).

Conclusions

The prevalence of sarcopenia in patients with EC, GC, or CRC during NAT is high, and it is associated with poorer clinical outcomes. Clinicians should closely monitor the changes in patients' body composition and guide patients to carry out a reasonable diet and appropriate exercise to improve their poor prognosis and quality of life.

Systematic review registration

CRD42023387817.

Effects of chemotherapy treatment on muscle strength indicators, functional capacity and biopsychosocial aspects of women with breast cancer

Evidences on the effects of chemotherapy treatment cycles on measures of muscle, mental state, social and cognitive performance are scarce. The objective of this study was to analyze the effects of chemotherapy cycles on muscle strength and activation, functional capacity, quality of life, fatigue and anxiety of women with breast cancer. Therefore, twenty-two women divided into a treatment group (n = 10; 46.6 ± 9.6 years) and control group (n = 12; 51.6 ± 7.0 years) participated in the study. Analysis of muscle performance, quality of life, fatigue and anxiety after the 2nd and 4th cycle of chemotherapy with anthracyclines were performed in women with breast cancer (TRA) and compared to healthy women (CTR). Two-way ANOVA was used to compare the variance of the means and the significance level was set as P≤0.05. The results showed Differences in the muscular activation of the vastus mediallis between the groups at post time (P = 0.038), as well as in the sit and stand test in the baseline (P<0.001) and post moment (P<0.001). Functional capacity performance was different between baseline (P<0.001) and post-time (P<0.001) groups. Additionally, the TRA group worsened the quality of life in the domains of functional capacity (P<0.001) and limitation of physical aspects (P = 0.002), besides presenting negative changes in fatigue. Thus, anthracycline chemotherapy cycles reduce muscular performance and affect biopsychosocial variables in women with breast cancer.

A Mixture of Morus alba and Angelica keiskei Leaf Extracts Improves Muscle Atrophy by Activating the PI3K/Akt/mTOR Signaling Pathway and Inhibiting FoxO3a In Vitro and In Vivo

Muscle atrophy, which is defined as a decrease in muscle mass and strength, is caused by an imbalance between the anabolism and catabolism of muscle proteins. Thus, modulating the homeostasis between muscle protein synthesis and degradation represents an efficient treatment approach for this condition. In the present study, the protective effects against muscle atrophy of ethanol extracts of Morus alba L. (MA) and Angelica keiskei Koidz. (AK) leaves and their mixtures (MIX) were evaluated in vitro and in vivo. Our results showed that MIX increased 5-aminoimidazole-4-carboxamide ribonucleotide-induced C2C12 myotube thinning, and enhanced soleus and gastrocnemius muscle thickness compared to each extract alone in dexamethasone-induced muscle atrophy Sprague Dawley rats. In addition, although MA and AK substantially improved grip strength and histological changes for dexamethasone-induced muscle atrophy in vivo, the efficacy was superior in the MIX-treated group. Moreover, MIX further increased the expression levels of myogenic factors (MyoD and myogenin) and decreased the expression levels of E3 ubiquitin ligases (atrogin-1 and muscle-specific RING finger protein-1) in vitro and in vivo compared to the MA- and AK-alone treatment groups. Furthermore, MIX increased the levels of phosphorylated phosphoinositide 3-kinase (PI3K), protein kinase B (Akt), and mammalian target of rapamycin (mTOR) that were reduced by dexamethasone, and downregulated the expression of forkhead box O3 (FoxO3a) induced by dexamethasone. These results suggest that MIX has a protective effect against muscle atrophy by enhancing muscle protein anabolism through the activation of the PI3K/Akt/mTOR signaling pathway and attenuating catabolism through the inhibition of FoxO3a.

Hallmarks of ageing in human skeletal muscle and implications for understanding the pathophysiology of sarcopenia in women and men

Ageing is a complex biological process associated with increased morbidity and mortality. Nine classic, interdependent hallmarks of ageing have been proposed involving genetic and biochemical pathways that collectively influence ageing trajectories and susceptibility to pathology in humans. Ageing skeletal muscle undergoes profound morphological and physiological changes associated with loss of strength, mass, and function, a condition known as sarcopenia. The aetiology of sarcopenia is complex and whilst research in this area is growing rapidly, there is a relative paucity of human studies, particularly in older women. Here, we evaluate how the nine classic hallmarks of ageing: genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, deregulated nutrient sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, and altered intercellular communication contribute to skeletal muscle ageing and the pathophysiology of sarcopenia. We also highlight five novel hallmarks of particular significance to skeletal muscle ageing: inflammation, neural dysfunction, extracellular matrix dysfunction, reduced vascular perfusion, and ionic dyshomeostasis, and discuss how the classic and novel hallmarks are interconnected. Their clinical relevance and translational potential are also considered.

The role of pharmacists in multimodal cancer cachexia care

Cancer cachexia is a complex syndrome, and multidisciplinary management has the potential to improve patient outcomes and efficiency of care. Multidisciplinary management consists primarily of exercise, nutrition, and pharmacotherapy. The pharmacist's role in cancer cachexia is to contribute to appropriate pharmacotherapy practices. For example, anamorelin is an oral drug with ghrelin-like effects that may improve the pathogenesis of cancer cachexia by stimulating appetite and increasing food intake and body weight. Many patients with cancer cachexia are under treatment with anticancer agents, and pharmacists need to determine whether symptoms such as anorexia and nausea are due to cancer cachexia or anticancer agents. Based on that determination, they are then expected to suggest supportive care to the physician. Provision of multidisciplinary care for cancer cachexia requires communication with not only physicians but also with nurses, dietitians, and other professionals so that nutritional therapy can be provided at the time cachexia is detected. However, the role of pharmacists in the management of cancer cachexia is not well established, and there is no evidence that pharmacist interventions are of benefit to patients. In this article, to contribute to the treatment of cancer cachexia by multidisciplinary care, we describe the role of pharmacists in cancer cachexia as currently practiced at our hospital. We also consider future challenges to this type of multidisciplinary care. Evidence concerning multidisciplinary treatment of cancer cachexia is scarce, including therapeutic agents, and there is a current lack of collaboration among medical professionals and education in cancer cachexia. Solving these problems will require efforts in the practice and evaluation of treatment for cancer cachexia.