Response of skeletal muscle RNA polymerases I and II to tumour growth.
The muscle wasting which occurs in animals bearing a transplantable tumour is accompanied by a decrease in the level of protein synthesis and a loss in RNA. This paper examines the behaviour of RNA polymerases I and II (EC 2.7.7.6) in nuclei isolated from skeletal muscle of rats bearing a Walker 256 carcinoma. Marked decreases were observed in template-engaged RNA polymerase I and II activities and in free RNA polymerase I activity. Free RNA polymerase II activity was unaltered. When assays were carried out at high (NH4)2SO4 concentration or in the presence of heparin the diminished RNA polymerase I activity was still apparent, but heparin and high ionic strength overcame the inhibition of RNA polymerase II. Loss of RNA polymerase I activity was associated with a decrease in the number of template-engaged enzyme molecules and in the polynucleotide elongation rate. The number of template-engaged RNA polymerase II molecules was unaltered by tumour growth, but the polynucleotide elongation rate was significantly reduced. No evidence was obtained for any alteration in ribonuclease activity in nuclei or whole muscles of tumour-bearing rats. These results demonstrate an effect of the tumor on transcription in skeletal muscle of its host.
Goodlad
G A
GA
Department of Biochemistry and Microbiology, University of St. Andrews, U.K.
Clark
C M
CM
D000546:Amanitins / Q000494:pharmacology; D000818:Animals; D002279:Carcinoma 256, Walker / Q000201:enzymology* / Q000473:pathology; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D003609:Dactinomycin / Q000494:pharmacology; D005260:Female; D009132:Muscles / Q000201:enzymology*; D012318:RNA Polymerase I / Q000378:metabolism*; D012319:RNA Polymerase II / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012016:Reference Values; D012260:Ribonucleases / Q000378:metabolism; D014158:Transcription, Genetic
D000546:Amanitins; D003609:Dactinomycin; D012319:RNA Polymerase II; D012318:RNA Polymerase I; D012260:Ribonucleases