title: Chemotherapy inhibits skeletal muscle ubiquitin-proteasome-dependent proteolysis.
abstract: Chemotherapy has cachectic effects, but it is unknown whether cytostatic agents alter skeletal muscle proteolysis. We hypothesized that chemotherapy-induced alterations in protein synthesis should result in the increased incidence of abnormal proteins, which in turn should stimulate ubiquitin-proteasome-dependent proteolysis. The effects of the nitrosourea cystemustine were investigated in skeletal muscles from both healthy and colon 26 adenocarcinoma-bearing mice, an appropriate model for testing the impact of cytostatic agents. Muscle wasting was seen in both groups of mice 4 days after a single cystemustine injection, and the drug further increased the loss of muscle proteins already apparent in tumor-bearing animals. Cystemustine cured the tumor-bearing mice with 100% efficacy. Surprisingly, within 11 days of treatment, rates of muscle proteolysis progressively decreased below basal levels observed in healthy control mice and contributed to the cessation of muscle wasting. Proteasome-dependent proteolysis was inhibited by mechanisms that include reduced mRNA levels for 20S and 26S proteasome subunits, decreased protein levels of 20S proteasome subunits and the S14 non-ATPase subunit of the 26S proteasome, and impaired chymotrypsin- and trypsin-like activities of the enzyme. A combination of cisplatin and ifosfamide, two drugs that are widely used in the treatment of cancer patients, also depressed the expression of proteasomal subunits in muscles from rats bearing the MatB adenocarcinoma below basal levels. Thus, a down-regulation of ubiquitin-proteasome-dependent proteolysis is observed with various cytostatic agents and contributes to reverse the chemotherapy-induced muscle wasting.
authors.affiliation: Human Nutrition Research Center, Nutrition and Protein Metabolism Unit, Institut National de la Recherche Agronomique de Theix, 63122 Ceyrat, France.
authors.forename: Thomas
authors.initials: T
authors.lastname: Tilignac
authors.forename: Sandrine
authors.initials: S
authors.lastname: Temparis
authors.forename: Lydie
authors.initials: L
authors.lastname: Combaret
authors.forename: Daniel
authors.initials: D
authors.lastname: Taillandier
authors.forename: Marie-Noëlle
authors.initials: MN
authors.lastname: Pouch
authors.forename: Matjaz
authors.initials: M
authors.lastname: Cervek
authors.forename: Diana M
authors.initials: DM
authors.lastname: Cardenas
authors.forename: Thierry
authors.initials: T
authors.lastname: Le Bricon
authors.forename: Eric
authors.initials: E
authors.lastname: Debiton
authors.forename: Susan E
authors.initials: SE
authors.lastname: Samuels
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Madelmont
authors.forename: Didier
authors.initials: D
authors.lastname: Attaix
mesh_terms: D000230:Adenocarcinoma / Q000188:drug therapy / Q000378:metabolism; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology* / Q000633:toxicity; D002100:Cachexia / Q000139:chemically induced / Q000201:enzymology / Q000378:metabolism; D002945:Cisplatin / Q000008:administration & dosage; D003110:Colonic Neoplasms / Q000188:drug therapy / Q000378:metabolism; D003546:Cysteine Endopeptidases / Q000378:metabolism; D005260:Female; D007069:Ifosfamide / Q000008:administration & dosage; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009097:Multienzyme Complexes / Q000037:antagonists & inhibitors* / Q000378:metabolism; D009124:Muscle Proteins / Q000096:biosynthesis / Q000378:metabolism*; D018908:Muscle Weakness / Q000139:chemically induced / Q000201:enzymology / Q000378:metabolism; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism*; D009607:Nitrosourea Compounds / Q000494:pharmacology* / Q000633:toxicity; D046988:Proteasome Endopeptidase Complex; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011916:Rats, Inbred F344; D025801:Ubiquitin / Q000037:antagonists & inhibitors* / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; D009097:Multienzyme Complexes; D009124:Muscle Proteins; D009607:Nitrosourea Compounds; D012333:RNA, Messenger; D025801:Ubiquitin; C051263:N'-(2-chloroethyl)-N-(2-(methylsulfonyl)ethyl)-N'-nitrosourea; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex; D002945:Cisplatin; D007069:Ifosfamide