5-Fluorouracil disrupts skeletal muscle immune cells and impairs skeletal muscle repair and remodeling

Age-related and cancer-related sarcopenia: is there a difference?

PURPOSE

The aim of this review is the attempt to differentiating the pathophysiologic and clinical features of the aging-related sarcopenia from cancer-related sarcopenia. In fact, there is some controversy among the experts mainly regarding two points: is always sarcopenia, even that aging-related one, the expression of a generalized disease or may exist independently and without major alteration of the muscle function? Are always aging-related and cancer-related sarcopenia completely separated entities?

RECENT FINDINGS

Literature shows that sarcopenia, defined as simple skeletal muscle mass loss, may range from a mainly focal problem which is common in many healthy elderly people, to a component of a complex multiorgan syndrome as cancer cachexia. Disuse, malnutrition and (neuro)degenerative processes can account for most of the aging-related sarcopenias while systemic inflammation and secretion of cancer-and immune-related molecules play an additional major role in cachexia.

SUMMARY

A multimodal approach including physical exercise and optimized nutritional support are the key measures to offset sarcopenia with some contribution by the anti-inflammatory drugs in cancer patients. Results are more promising in elderly patients and are still pending for cancer patients where a more specific approach will only rely on the identification and contrast of the key mediators of the cachectic process.

Obesity worsens mitochondrial quality control and does not protect against skeletal muscle wasting in murine cancer cachexia

BACKGROUND

More than 650 million people are obese (BMI > 30) worldwide, which increases their risk for several metabolic diseases and cancer. While cachexia and obesity are at opposite ends of the weight spectrum, leading many to suggest a protective effect of obesity against cachexia, mechanistic support for obesity's benefit is lacking. Given that obesity and cachexia are both accompanied by metabolic dysregulation, we sought to investigate the impact of obesity on skeletal muscle mass loss and mitochondrial dysfunction in murine cancer cachexia.

METHODS

Male C57BL/6 mice were given a purified high fat or standard diet for 16 weeks before being implanted with 106 Lewis lung carcinoma (LLC) cells. Mice were monitored for 25 days, and hindlimb muscles were collected for cachexia indices and mitochondrial assessment via western blotting, high-resolution respirometry and transmission electron microscopy (TEM).

RESULTS

Obese LLC mice experienced significant tumour-free body weight loss similar to lean (-12.8% vs. -11.8%, P = 0.0001) but had reduced survival (33.3% vs. 6.67%, χ2  = 10.04, P = 0.0182). Obese LLC mice had reduced muscle weights (-24%, P < 0.0354) and mCSA (-16%, P = 0.0004) with similar activation of muscle p65 (P = 0.0337), and p38 (P = 0.0008). ADP-dependent coupled respiration was reduced in both Obese and Obese LLC muscle (-30%, P = 0.0072) consistent with reductions in volitional cage activity (-39%, P < 0.0001) and grip strength (-41%, P < 0.0001). TEM revealed stepwise reductions in intermyofibrillar and subsarcolemmal mitochondrial size with Obese (IMF: -37%, P = 0.0009; SS: -21%, P = 0.0101) and LLC (IMF: -40%, P = 0.0019; SS: -27%, P = 0.0383) mice. Obese LLC mice had increased pAMPK (T172; P = 0.0103) and reduced FIS1 (P = 0.0029) and DRP1 (P < 0.0001) mitochondrial fission proteins, which were each unchanged in Lean LLC. Further, mitochondrial TEM analysis revealed that Obese LLC mice had an accumulation of damaged and dysfunctional mitochondria (IMF: 357%, P = 0.0395; SS: 138%, P = 0.0174) in concert with an accumulation of p62 (P = 0.0328) suggesting impaired autophagy and clearance of damaged mitochondria. Moreover, we observed increases in electron lucent vacuoles only in Obese LLC muscle (IMF: 421%, P = 0.0260; SS: 392%, P = 0.0192), further supporting an accumulation of damaged materials that cannot be properly cleared in the obese cachectic muscle.

CONCLUSIONS

Taken together, these results demonstrate that obesity is not protective against cachexia and suggest exacerbated impairments to mitochondrial function and quality control with a particular disruption in the removal of damaged mitochondria. Our findings highlight the need for consideration of the severity of obesity and pre-existing metabolic conditions when determining the impact of weight status on cancer-induced cachexia and functional mitochondrial deficits.

The complex heterogeneity of immune cell signatures across wasting tissues with C26 and 5-fluorouracil-induced cachexia

Immune cell-driven pathways are linked to cancer cachexia. Tumor presence is associated with immune cell infiltration whereas cytotoxic chemotherapies reduce immune cell counts. Despite these paradoxical effects, both cancer and chemotherapy can cause cachexia; however, our understanding of immune responses in the cachexia condition with cancer and chemotherapy is largely unknown. We sought to advance our understanding of the immunology underlying cancer and cancer with chemotherapy-induced cachexia. CD2F1 mice were given 106 C26 cells, followed by five doses of 5-fluorouracil (5FU; 30 mg/kg LM, ip) or PBS. Indices of cachexia and tumor (TUM), skeletal muscle (SKM), and adipose tissue (AT) immune cell populations were examined using high-parameter flow cytometry. Although 5FU was able to stunt tumor growth, % body weight loss and muscle mass were not different between C26 and C26 + 5FU. C26 increased CD11b+Ly6g+ and CD11b+Ly6cInt inflammatory myeloid cells in SKM and AT; however, both populations were reduced with C26 + 5FU. tSNE analysis revealed 24 SKM macrophage subsets wherein 8 were changed with C26 or C26 + 5FU. C26 + 5FU increased SKM CD11b-CD11c+ dendritic cells, CD11b-NK1.1+ NK-cells, and CD11b-B220+ B-cells, and reduced Ly6cHiCX3CR1+CD206+CD163IntCD11c-MHCII- infiltrated macrophages and other CD11b+Ly6cHi myeloid cells compared with C26. Both C26 and C26 + 5FU had elevated CD11b+F480+CD206+MHCII- or more specifically Ly6cLoCX3CR1+CD206+CD163IntCD11c-MHCII- profibrotic macrophages. 5FU suppressed tumor growth and decreased SKM and AT inflammatory immune cells without protecting against cachexia suggesting that these cells are not required for wasting. However, profibrotic cells and muscle inflammatory/atrophic signaling appear consistent with cancer- and cancer with chemotherapy-induced wasting and remain potential therapeutic targets.NEW & NOTEWORTHY Despite being an immune-driven condition, our understanding of skeletal muscle and adipose tissue immune cells with cachexia is limited. Here, we identified immune cell populations in tumors, skeletal muscle, and adipose tissue in C26 tumor-bearing mice with/without 5-fluorouracil (5FU). C26 and C26 + 5FU had increased skeletal muscle profibrotic macrophages, but 5FU reduced inflammatory myeloid cells without sparing mass. Tumor presence and chemotherapy have contrasting effects on certain immune cells, which appeared not necessary for wasting.

Modified pectin with anticancer activity in breast cancer: A systematic review

Breast cancer is the most commonly diagnosed cancer among women worldwide. The current pharmacological treatments for breast cancer have numerous adverse effects and are not always effective. Recently, the anticancer activity of modified pectins (MPs) against various types of cancers, including breast cancer, has been investigated. This systematic review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) model, including scientific articles from the last 22 years that measured the anticancer activity of MPs on breast cancer. The articles were searched in four databases with the terms: "modified pectin" and "breast cancer". Nine articles were included, five in vitro and four mixed (in vitro and in vivo). Different models and methods by which anticancer activity was measured were analyzed. All the studies reported positive results in both cell lines and in vivo murine models of breast cancer. The extracted data suggest a positive effect and provide mechanistic evidence of MPs in the treatment of breast cancer. However, as limited number of studies were included, further in vivo studies are required to obtain more conclusive preclinical evidence.

Gastric Cancer with Sarcopenia: an Area Worth Focusing On

OPINION STATEMENT

Gastric cancer (GC) is the fifth most common cancer and the third leading cause of cancer death worldwide, which seriously endangers human health. A number of studies have shown that sarcopenia occurs more frequently in patients with gastric cancer than in the general population and can significantly affect the disease status and survival of patients, which is of great significance in predicting the prognosis of gastric cancer. Patients with gastric cancer may suffer sarcopenia no matter before or after surgery, and the pathogenesis is complex. Abnormal nutrient metabolism and reduced exercise are the leading causes. In addition, surgical treatment and chemotherapy for gastric cancer might participate in the physiological and pathological mechanism of sarcopenia. Generally speaking, exercise and nutritional therapy are the main prevention and treatment methods for sarcopenia. But more prospective evidence is needed to establish reasonable interventions, and other drug treatments are in their infancy. For the diagnostic criteria of sarcopenia, the cut-off values of the skeletal muscle mass index obtained from CT images vary widely and need to be standardized and unified. We also need to explore simple predictors to facilitate sarcopenia risk assessment. More research is needed to formulate more appropriate treatments for gastric cancer patients with sarcopenia.

Muscle and Adipose Wasting despite Disease Control: Unaddressed Side Effects of Palliative Chemotherapy for Pancreatic Cancer

Muscle and adipose wasting during chemotherapy for advanced pancreatic cancer (aPC) are associated with poor outcomes. We aimed to quantify the contributions of chemotherapy regimen and tumour progression to muscle and adipose wasting and evaluate the prognostic value of each tissue loss. Of all patients treated for aPC from 2013-2019 in Alberta, Canada (n = 504), computed-tomography (CT)-defined muscle and adipose tissue index changes (∆SMI, ∆ATI, cm2/m2) were measured for patients with CT images available both prior to and 12 ± 4 weeks after chemotherapy initiation (n = 210). Contributions of regimen and tumour response to tissue change were assessed with multivariable linear regression. Survival impacts were assessed with multivariable Cox's proportional hazards models. Tissue changes varied widely (∆SMI: -17.8 to +7.3 cm2/m2, ∆ATI: -106.1 to +37.7 cm2/m2) over 116 (27) days. Tumour progression contributed to both muscle and adipose loss (-3.2 cm2/m2, p < 0.001; -12.4 cm2/m2, p = 0.001). FOLFIRINOX was associated with greater muscle loss (-1.6 cm2/m2, p = 0.013) and GEM/NAB with greater adipose loss (-11.2 cm2/m2, p = 0.002). The greatest muscle and adipose losses were independently associated with reduced survival (muscle: HR 1.72, p = 0.007; adipose: HR 1.73, p = 0.012; tertile 1 versus tertile 3). Muscle and adipose losses are adverse effects of chemotherapy and may require regimen-specific management strategies.

Low Muscle Mass and Radiodensity Associate with Impaired Pulmonary Function and Respiratory Complications in Patients with Esophageal Cancer

BACKGROUND

Sixty percent of patients with esophageal cancer display signs of cachexia at diagnosis. Changes in body composition are common, and muscle mass and quality are measurable through imaging studies. Cachexia leads to functional impairments that complicate treatments, including surgery. We hypothesize that low muscle mass and quality associate with pulmonary function testing parameters, highlighting ventilatory deficits, and postoperative complications in patients receiving esophagectomy.

STUDY DESIGN

We performed a retrospective review of patients receiving esophagectomy between 2012 and 2021 at our facility. PET/CT scans were used to quantify skeletal muscle at the L3 and T4 levels. Patient characteristics were recorded, including pulmonary function testing parameters. Regression models were created to characterize predictive associations.

RESULTS

One hundred eight patients were identified. All were included in the final analysis. In linear regression adjusted for sex, age, and COPD status, low L3 muscle mass independently associated with low forced vital capacity (p < 0.005, β 0.354) and forced expiratory volume in 1 second (p < 0.001, β 0.392). Similarly, T4 muscle mass independently predicted forced vital capacity (p < 0.005, β 0.524) and forced expiratory volume in 1 second (p < 0.01, β 0.480). L3 muscle quality correlated with total lung capacity ( R 0.2463, p < 0.05). Twenty-six patients had pleural effusions postoperatively, associated with low muscle quality on L3 images (p < 0.05). Similarly, patients with hospitalization more than 2 weeks presented with lower muscle quality (p < 0.005).

CONCLUSIONS

Cachexia and low muscle mass are common. Reduced muscle mass and quality independently associate with impaired forced vital capacity, forced expiratory volume in 1 second, and total lung capacity. We propose that respiratory muscle atrophy occurs with weight loss. Body composition analyses may aid in stratifying patients. Pulmonary function testing may also serve as a functional endpoint for clinical trials. These findings highlight the need to study mechanisms that lead to respiratory muscle pathology and dysfunction in tumor-bearing hosts.

Adverse effects of systemic cancer therapy on skeletal muscle: myotoxicity comes out of the closet

PURPOSE OF REVIEW

Systemic cancer therapy-associated skeletal muscle wasting is emerging as a powerful impetus to the overall loss of skeletal muscle experienced by patients with cancer. This review explores the clinical magnitude and biological mechanisms of muscle wasting during systemic cancer therapy to illuminate this adverse effect. Emerging strategies for mitigation are also discussed.

RECENT FINDINGS

Clinical findings include precise, specific measures of muscle loss over the course of chemotherapy, targeted therapy and immunotherapy. All these therapeutic classes associate with quantitatively important muscle loss, independent of tumor response. Parallel experimental studies provide understanding of the specific molecular basis of wasting, which can include inhibition of protein synthesis, proliferation and differentiation, and activation of inflammation, reactive oxygen species, autophagy, mitophagy, apoptosis, protein catabolism, fibrosis and steatosis in muscle. Strategies to mitigate these muscle-specific adverse effects of cancer therapy remain in the earliest stages of development.

SUMMARY

The adverse side effect of cancer therapy on skeletal muscle has been largely ignored in the development of cancer therapeutics. Given the extent to which loss of muscle mass and function can bear on patients' function and quality of life, protection/mitigation of these side effects is a research priority.

Quercetin Improved Muscle Mass and Mitochondrial Content in a Murine Model of Cancer and Chemotherapy-Induced Cachexia

A cachexia diagnosis is associated with a doubling in hospital stay and increased healthcare cost for cancer patients and most cachectic patients do not survive treatment. Unfortunately, complexity in treating cachexia is amplified by both the underlying malignancy and the anti-cancer therapy which can independently promote cachexia. Quercetin, an organic polyphenolic flavonoid, has demonstrated anti-inflammatory and antioxidant properties with promise in protecting against cancer and chemotherapy-induced dysfunction; however, whether quercetin is efficacious in maintaining muscle mass in tumor-bearing animals receiving chemotherapy has not been investigated. C26 tumor-bearing mice were given 5-fluorouracil (5FU; 30 mg/kg of lean mass i.p.) concomitant with quercetin (Quer; 50 mg/kg of body weight via oral gavage) or vehicle. Both C26 + 5FU and C26 + 5FU + Quer had similar body weight loss; however, muscle mass and cross-sectional area was greater in C26 + 5FU + Quer compared to C26 + 5FU. Additionally, C26 + 5FU + Quer had a greater number and larger intermyofibrillar mitochondria with increased relative protein expression of mitochondrial complexes V, III, and II as well as cytochrome c expression. C26 + 5FU + Quer also had increased MFN1 and reduced FIS1 relative protein expression without apparent benefits to muscle inflammatory signaling. Our data suggest that quercetin protected against cancer and chemotherapy-induced muscle mass loss through improving mitochondrial homeostatic balance.