Development of metabolic and contractile alterations in development of cancer cachexia in female tumor-bearing mice

Abstract

Cancer cachexia (CC) results in impaired muscle function and quality of life and is the primary cause of death for ~20-30% of cancer patients. We demonstrated mitochondrial degeneration as a precursor to CC in male mice, however, if such alterations occur in females is currently unknown. The purpose of this study was to elucidate muscle alterations in CC development in female tumor-bearing mice. 60 female C57BL/6J mice were injected with PBS or Lewis Lung Carcinoma at 8-week age, and tumors developed for 1, 2, 3, or 4 weeks to assess the time course of cachectic development. In vivo muscle contractile function, protein fractional synthetic rate (FSR), protein turnover, and mitochondrial health were assessed. 3- and 4-week tumor-bearing mice displayed a dichotomy in tumor growth and were reassigned to High Tumor (HT) and Low Tumor (LT) groups. HT mice exhibited lower soleus, TA, and fat weights compared to PBS. HT mice showed lower peak isometric torque and slower one-half relaxation time compared to PBS. HT mice had lower FSR compared to PBS while E3 ubiquitin ligases were greater in HT compared to other groups. Bnip3 (mitophagy) and pMitoTimer red puncta (mitochondrial degeneration) were greater in HT while Pgc1α1 and Tfam (mitochondrial biogenesis) were lower in HT compared to PBS. We demonstrate alterations in female tumor-bearing mice where HT exhibited greater protein degradation, impaired muscle contractility, and mitochondrial degeneration compared to other groups. Our data provide novel evidence for a distinct cachectic development in tumor-bearing female mice compared to previous male studies.

PGC-1α overexpression is not sufficient to mitigate cancer cachexia in either male or female mice

“…Male mice seem to display more prominent changes in reduction of mitophagy markers, and this could be the result of lesser mitochondrial efficiency or "basal protection" of mitochondria in males compared with females. Recent studies from our group and others support this hypothesis, whereby female mice seem to display blunted oxidative stress through induction of autophagy and mitophagy compared with male mice submitted to hindlimb unloading (Brown et al 2017b;Rosa-Caldwell et al 2020Lim et al 2022). We hypothesize that although mitochondrial biogenesis is elevated, it is not sufficient to improve mitochondrial quality and prevent muscle loss induced by cancer, thus, does not protect from muscle wasting and reduce mRNA content of important mitophagy promoters such as Bnip3 and Beclin possibly reducing clearance of damaged mitochondria noted by increased red puncta.…”

“…Impaired energy metabolism in response to tumor-derived factors and an associated inflammatory response seems to largely influence muscle wasting in CC (Ballarò et al 2021). Studies from our laboratory and others (Asp et al 2010;Brown et al 2017b;Ballarò et al 2021;Lim et al 2022) associate metabolic crisis due to mitochondrial impairments prior to the onset of CC and suggest a connection between mitochondrial aberrations and muscle atrophy preceding CC development. Therefore, promoting mitochondrial health and dynamics represents an interesting target for the development of therapies to prevent or mitigate CC outcomes.…”

“…Wang et al utilized 4month-old female mice only, with cachexia assessment accelerated and assessed at 2 weeks of tumor development, representing an earlier timepoint for cachexia compared with other LLC studies from the literature which commonly utilize endpoints around 4 weeks tumor development (Puppa et al 2014;Brown et al 2017b;H. Lee et al 2017;Lim et al 2022). Age of tumor inoculation, biological sexes, and duration of tumor development represent important scientific significance for cachexia phenotype.…”

“…Likewise, most preclinical studies in CC are focused on males, not accounting for phenotypical disparities between biological sexes reported in multiple human cancer types, such as lung cancer (Cosper and Leinwand 2011). Previous studies from our laboratory indicate differences in biological sex in several distinct muscle atrophy models (Brown et al 2017b(Brown et al , 2018Lim et al 2020Lim et al , 2022Rosa-Caldwell et al 2021). In fact, males appear to be more so affected by inflammation-induced muscle atrophy models than females, such as cancer-induced atrophy, whereby females concomitantly display lower ubiquitinproteasome activity when compared with males during CC Appl.…”

Reducing White Adipose Tissue Browning Using p38α MAPK Inhibitors Ameliorates Cancer-Associated Cachexia as Assessed by Magnetic Resonance Imaging

“…The use of experimental animals followed the 3 R (reduction, replacement, refinement) principles. Because previous studies reported that female animals exhibit estrogen-driven protective responses to the metabolic perturbations and CAC development [ 27 , 28 ], we only used male C57BL/6J mice in this preliminary study to exclude this potential interfering factor. Animals were housed at a room temperature of 22 ± 0.5 °C on a 12 h light and 12 h dark cycle with pair-feeding and free access to water.…”