Metabolic Characteristics And Molecular Mechanisms Of Muscle Atrophy Of Cancer Cachexia Based On Metabolomic Analysis

Cachexia is a complex metabolic derangement syndrome characterized by depletion of skeletal muscle mass(with or without loss of fat mass)and severe body function impairment.It has a dramatic impact on quality and length of life for 80%of cancer patients.However,the metabolic characteristics and molecular mechanisms of cancer cachexia are still unclear.In the present study,we focus on investigating the cachexia symptoms of glioma and gastric cancer on the established animal models.The comprehensive understanding of muscle wasting of cancer cachexia is accomplished by a combination of signaling pathway analysis and NMR-based metabolomic analysis.The characteristic metabolites and key metabolic pathways closely related to the glioma cachexia and gastric cancer cachexia are revealed,respectively.These works provide hints for the early diagnosis and developments of new therapeutics for glioma cachexia and gastric cancer cachexia.In this study,sera,brains,gastrocnemius muscles,mesenteric adipose,hearts,livers,spleens and kidneys were collected in BALB/c nude mice orthotopicly implanted with human glioma(WHO II CHG5 and WHO IV U87)cells.According to the WHO standards and histologic results,the model mice were divided into three groups:control group,Low malignant grade CHG5 group and high malignant grade U87 group.Cachexia symptoms of mice were depicted by phenotypic,histopathologic,physiological and biochemical analyses.U87 mice developed cachexia much earlier and more severe than CHG5 mice.In U87,glioma growth significantly shortened the survival of mice,decreased adipose and lean body mass,reduced food consumption,induced multi-organ atrophy,and increased systemic inflammation.It also causes significantly decreased skeletal muscle mass and strength,which are associated with down-regulated AKT,and up-regulated AMPK,FOXO and Atroginl.Interestingly,expressions of MuRF1,MyoDl and eIF3f are not significantly changed.Metabolic differences in sera and gastrocnemius muscles were identified by NMR-based metabolomic analysis.Multivariate analysis including PCA and PLS-DA exhibited that the metabolic profiles of glioma cachexia mice were clearly distinguished from those of control mice.The differential metabolites were identified by using the one-way ANOVA and the involved metabolic pathways were elucidated.The significantly perturbed metabolic pathways in sera included glycolysis and lipolysis,phenylalanine and tyrosine metabolism.The significantly perturbed metabolic pathways in gastrocnemius muscles included glucose and lipid metabolism,protein catabolism,amino acid metabolism and TCA cycle anaplerotic flux.Overall,the metabolic alterations in serum were much more sensitive and complicated than gastrocnemius muscles.The metabolic changes identified here might potentially provide potential blood biomarkers for glioma cachexia.On the other hand,sera,gastrocnemius muscles,and gastric tissues were collected in BALB/c nude mice orthotopicly implanted with human gastric cancer cell BGC823.The BGC823 model with typical cachexia symptoms,confirmed by significant weight loss and muscle atrophy,showed distinctly distinguished metabolic profiles of tumors,sera and gastrocnemius from sham mice.The OPLS-DA loading plots and univariate analysis were used to identify differential metabolites that were significantly responsible for the metabolic separations between the two groups of mice.The significantly perturbed metabolic pathways in gastric tissues included glucose and nucleic acid metabolism.The significantly perturbed metabolic alterations in sera were closely related to hyperlipidemia and hypoglycemia.Furthermore,gastrocnemius transcriptomic and metabolomic data revealed that gastric cancer cachexia(GCC)induced perturbed pathways mainly concentrated on carbohydrate and amino acid metabolism.Specifically,cachectic gastrocnemius exhibited increased a-ketoglutarate(AKG)and decreased glucose.In vitro study indicated that a-ketoglutarate could reduce glucose deficiency-induced myoblasts slow proliferation and myotubes atrophy.Overall,this work provides a global metabolic overview to understand the metabolic alterations associated with GCC-induced muscle atrophy.Results highlighted the role of AKG in skeletal muscle protein turnover.These AKG-relevant results might be beneficial to explore potential clinical implications of AKG supplements in prevention and therapy of cancer cachexia.In conclusion,we established orthotopic preclinical models of glioma cachexia and gastric cancer cachexia.The cachexia symptoms of glioma,and the signal pathways and metabolic pathways related to muscle atrophy were revealed.The systematic metabolic alterations associated with muscle atrophy induced by gastric cancer cachexia were conducted.This work laid the foundation for elucidating the metabolic characteristics and molecular mechanisms of glioma cachexia and gastric cancer cachexia.It would be also benefit to the early diagnosis of glioma cachexia and provides hints for the developments of new therapeutics for gastric cancer cachexia.