Increased steady-state levels of several mitochondrial and nuclear gene transcripts in rat hepatoma with a low content of mitochondria.
Cells from a rapidly growing rat Zajdela hepatoma were shown to contain (on a protein basis) five-times less mitochondria than hepatocytes from resting or regenerating rat liver. Transcripts of four nuclear genes for representative mitochondrial membrane proteins (beta-F1 subunit and N,N'-dicyclohexyl-carbodiimide-binding protein of ATP synthase, subunit IV of cytochrome oxidase and ADP/ATP translocase) were present in 2-4 times higher amounts in the poly(A)-rich RNA of the hepatoma than in the corresponding RNA fraction from resting or regenerating rat liver. The liver and hepatoma transcripts for the beta-F1 subunit were translated in an in-vitro system with equal efficiency. Pulse-chase labeling of isolated Zajdela hepatoma cells and hepatocytes from resting and regenerating liver revealed a relative excess of the newly synthesized beta-F1 subunit in the tumor cells. The half-life of the beta-F1 subunit was significantly shorter in the hepatoma cells than in hepatocytes from resting and regenerating liver. The contents of transcripts of three mitochondrial genes examined (cytochrome oxidase subunits I and II and NADH-ubiquinone reductase subunit 2) in Zajdela hepatoma mitochondria were about five-times higher than in the mitochondria of the resting cells and 3-4 times higher than in the organelles of the regenerating organ. The results indicate that events other than transcription (most likely post-translational) may be responsible for the reduced content of mitochondria in tumor cells.
Luciaková
K
K
Cancer Research Institute, Slovak Academy of Sciences, Bratislavia, Czechoslovakia.
Kuzela
S
S
D000818:Animals; D015152:Blotting, Northern; D002467:Cell Nucleus / Q000378:metabolism*; D015342:DNA Probes; D004272:DNA, Mitochondrial / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field; D008099:Liver / Q000166:cytology / Q000201:enzymology / Q000502:physiology; D008114:Liver Neoplasms, Experimental / Q000201:enzymology / Q000378:metabolism*; D008115:Liver Regeneration; D008297:Male; D008930:Mitochondria, Liver / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics*; D011061:Poly A / Q000235:genetics; D014176:Protein Biosynthesis; D006180:Proton-Translocating ATPases / Q000096:biosynthesis; D012313:RNA / Q000235:genetics; D012333:RNA, Messenger; D051381:Rats; D011919:Rats, Inbred Strains; D014158:Transcription, Genetic
D015342:DNA Probes; D004272:DNA, Mitochondrial; D009687:Nuclear Proteins; D012333:RNA, Messenger; D011061:Poly A; D012313:RNA; D006180:Proton-Translocating ATPases