Increased muscle proteasome activity correlates with disease severity in gastric cancer patients.
OBJECTIVE
To investigate the state of activation of the ATP-ubiquitin-dependent proteolytic system in the skeletal muscle of gastric cancer patients.


BACKGROUND
Muscle wasting in experimental cancer cachexia is frequently associated with hyperactivation of the ATP-dependent ubiquitin-proteasome proteolytic system. Increased muscle ubiquitin mRNA levels have been previously shown in gastric cancer patients, suggesting that this proteolytic system might be modulated also in human cancer.


METHODS
Biopsies of the rectus abdominis muscle were obtained intraoperatively from 23 gastric cancer patients and 14 subjects undergoing surgery for benign abdominal diseases, and muscle ubiquitin mRNA expression and proteasome proteolytic activities were assessed.


RESULTS
Muscle ubiquitin mRNA was hyperexpressed in gastric cancer patients compared to controls. In parallel, three proteasome proteolytic activities (CTL, chymotrypsin-like; TL, trypsin-like; PGP, peptidyl-glutamyl-peptidase) significantly increased in gastric cancer patients with respect to controls. Advanced tumor stage, poor nutritional status, and age more than 50 years were associated with significantly higher CTL activity but had no influence on TL and PGP activity.


CONCLUSIONS
These results confirm the involvement of the ubiquitin-proteasome proteolytic system in the pathogenesis of muscle protein hypercatabolism in cancer cachexia. The observation that perturbations of this pathway in gastric cancer patients occur even before clinical evidence of body wasting supports the thinking that specific pharmacologic and metabolic approaches aimed at counteracting the upregulation of this pathway should be undertaken as early as cancer is diagnosed.
Bossola
Maurizio
M
Istituto di Clinica Chirurgica, Università Cattolica del Sacro Cuore, Roma, Italy. maubosso@tin.it
Muscaritoli
Maurizio
M
Costelli
Paola
P
Grieco
Gabriella
G
Bonelli
Gabriella
G
Pacelli
Fabio
F
Rossi Fanelli
Filippo
F
Doglietto
Giovanni Battista
GB
Baccino
Francesco Maria
FM
D001706:Biopsy; D002918:Chymotrypsin / Q000378:metabolism; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D010450:Endopeptidases / Q000378:metabolism; D005260:Female; D015870:Gene Expression; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D008875:Middle Aged; D009097:Multienzyme Complexes / Q000378:metabolism*; D009752:Nutritional Status; D046988:Proteasome Endopeptidase Complex; D012333:RNA, Messenger / Q000378:metabolism; D017568:Rectus Abdominis / Q000378:metabolism*; D013274:Stomach Neoplasms / Q000378:metabolism* / Q000473:pathology; D014357:Trypsin / Q000378:metabolism; D025801:Ubiquitin / Q000235:genetics / Q000378:metabolism*; D015431:Weight Loss
D009097:Multienzyme Complexes; D012333:RNA, Messenger; D025801:Ubiquitin; D010450:Endopeptidases; D002918:Chymotrypsin; D014357:Trypsin; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex; C114177:peptidylglutamylpeptide hydrolase