Obesity reduced survival with 5-fluorouracil and did not protect against chemotherapy-induced cachexia or immune cell cytotoxicity in mice

Metabolic underpinnings of cancer-related fatigue

Cancer-related fatigue (CRF) is one of the most prevalent and detrimental complications of cancer. Emerging evidence suggests that obesity and insulin resistance are associated with CRF occurrence and severity in cancer patients and survivors. In this narrative review, we analyzed recent studies including both preclinical and clinical research on the relationship between obesity and/or insulin resistance and CRF. We also describe potential mechanisms for these relationships, though with the caveat that because the mechanisms underlying CRF are incompletely understood, the mechanisms mediating the association between obesity/insulin resistance and CRF are similarly incompletely delineated. The data suggest that, in addition to their effects to worsen CRF by directly promoting tumor growth and metastasis, obesity and insulin resistance may also contribute to CRF by inducing chronic inflammation, neuroendocrinological disturbance, and metabolic alterations. Furthermore, studies suggest that patients with obesity and insulin resistance experience more cancer-induced pain and are at more risk of emotional and behavioral disruptions correlated with CRF. However, other studies implied a potentially paradoxical impact of obesity and insulin resistance to reduce CRF symptoms. Despite the need for further investigation utilizing interventions to directly elucidate the mechanisms of cancer-related fatigue, current evidence demonstrates a correlation between obesity and/or insulin resistance and CRF, and suggests potential therapeutics for CRF by targeting obesity and/or obesity-related mediators.

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.

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.

Body Composition as a Predictor of the Survival in Anal Cancer

Background and aim: Sarcopenia and body composition parameters such as visceral and subcutaneous adipose tissue and visceral-to-subcutaneous adipose tissue ratio have been shown to be relevant biomarkers for prognosis in patients with different types of cancer. However, these findings have not been well studied in anal cancer to date. Therefore, the aim of this study was to evaluate the prognostic value of different body composition parameters in patients undergoing radiation therapy for the treatment of anal cancer with curative intent. Material and Methods: After approval by the institutional ethical committee, we retrospectively identified 81 patients in our local registry, who received radical intensity-modulated radiotherapy for the management of anal squamous cell cancer (ASCC). Clinical information, including body mass index (BMI), survival, and toxicities outcome, were retrieved from the local hospital registry. Based on the pre-therapeutic computer tomography (CT), we measured the total psoas muscle area, visceral adipose tissue area (VAT), subcutaneous adipose tissue area (SAT), and visceral-to-subcutaneous adipose tissue area ratio (VSR). In addition to the classical prognostic factors as T-stage, N-stage, gender, and treatment duration, we analyzed the impact of body composition on the prognosis in univariate and multivariate analyses. Results: Sarcopenia was not associated with increased mortality in anal cancer patients, whereas increased BMI (≥27 kg/m²) and VSR (≥0.45) were significantly associated with worsened overall survival and cancer-specific survival in both univariate and multivariate analyses. VSR-not BMI-was statistically higher in males. Sarcopenia and VSR ≥ 0.45 were associated with advanced T-stages. None of the body composition parameters resulted in a significant increase in treatment-related toxicities. Conclusion: BMI and visceral adiposity are independent prognostic factors for the survival of patients with anal cancer. Measurements to treat adiposity at the time of diagnosis may be needed to improve the survival outcomes for the affected patients.