Regulation of growth in a neoplastic B cell line by transfected subunits of 3',5'-cyclic adenosine monophosphate-dependent protein kinase.
cAMP inhibits the proliferation of both normal peripheral blood B and T lymphocytes as well as the proliferation of a human neoplastic B precursor cell line (Reh). To positively show that this is mediated via the the catalytic subunit, C alpha, of cAMP-dependent protein kinase, stably transfected Reh cell lines overexpressing C alpha were established. This was achieved by transfection with a construct confering hygromycin resistance together with a zinc-inducible expression of C alpha from the human metallothionine promoter. C alpha transfected clones were shown to confer a 2- to 2.5-fold zinc-dependent increase in C alpha messenger RNA, immunoreactive C, and phosphotransferase activity. The growth rate of clones transfected with C alpha was retarded, and a zinc-dependent inhibition of cell proliferation was demonstrated in the presence of a small trigger dose of forskolin. In contrast, overexpression of the regulatory subunit I alpha had no effect on cAMP-dependent inhibition of cell proliferation. Furthermore, expression of mutant regulatory subunit I alpha AB, which renders cAMP-dependent protein kinase unresponsive to cAMP, clearly protected against that inhibitory effect of cAMP. These data provides evidence that activation of the C subunit (C alpha) of cAMP-dependent protein kinase mediates the inhibitory action of cAMP on cell proliferation in Reh cells.
Institute of Medical Biochemistry, University of Oslo, Norway.
K
K
Taskén
K B
KB
Andersson
B K
BK
Erikstein
V
V
Hansson
T
T
Jahnsen
H K
HK
Blomhoff
D001402:B-Lymphocytes / Q000187:drug effects / Q000473:pathology*; D015152:Blotting, Northern; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000502:physiology*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000235:genetics* / Q000494:pharmacology*; D004273:DNA, Neoplasm / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D006801:Humans; D009154:Mutation; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000235:genetics / Q000473:pathology*; D012334:RNA, Neoplasm / Q000032:analysis / Q000235:genetics; D013936:Thymidine / Q000378:metabolism; D014162:Transfection; D014407:Tumor Cells, Cultured; D015032:Zinc / Q000494:pharmacology
D004273:DNA, Neoplasm; D012334:RNA, Neoplasm; D005576:Colforsin; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D015032:Zinc; D013936:Thymidine