An immortalized human cell line bearing a PRKAR1A-inactivating mutation: effects of overexpression of the wild-type Allele and other protein kinase A subunits.
BACKGROUND
Inactivating mutations of PRKAR1A, the regulatory subunit type 1A (RIalpha) of protein kinase A (PKA), are associated with tumor formation.


OBJECTIVE
Our objective was to evaluate the role of PKA isozymes on proliferation and cell cycle.


METHODS
A cell line with RIalpha haploinsufficiency due to an inactivating PRKAR1A mutation (IVS2+1 G-->A) was transfected with constructs encoding PKA subunits. Genetics, PKA subunit mRNA and protein expression and proliferation, aneuploidy, and cell cycle status were assessed. To identify factors that mediate PKA-associated cell cycle changes, we studied E2F and cyclins expression in transfected cells and E2F's role by small interfering RNA; we also assessed cAMP levels and baseline and stimulated cAMP signaling in transfected cells.


RESULTS
Introduction of PKA subunits led to changes in proliferation and cell cycle: a decrease in aneuploidy and G(2)/M for the PRKAR1A-transfected cells and an increase in S phase and aneuploidy for cells transfected with PRKAR2B, a known PRKAR1A mutant (RIalphaP), and the PKA catalytic subunit. There were alterations in cAMP levels, PKA subunit expression, cyclins, and E2F factors; E2F1 was shown to possibly mediate PKA effects on cell cycle by small interfering RNA studies. cAMP levels and constitutive and stimulated cAMP signaling were altered in transfected cells.


CONCLUSIONS
This is the first immortalized cell line with a naturally occurring PRKAR1A-inactivating mutation that is associated in vivo with tumor formation. PKA isozyme balance is critical for the control of cAMP signaling and related cell cycle and proliferation changes. Finally, E2F1 may be a factor that mediates dysregulated PKA's effects on the cell cycle.
Nesterova
Maria
M
Section on Endocrinology and Genetics, Developmental Endocrinology Branch, National Institute of Child Health and Human Development, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA. nesterom@mail.nih.gov
Bossis
Ioannis
I
Wen
Feng
F
Horvath
Anelia
A
Matyakhina
Ludmila
L
Stratakis
Constantine A
CA
D000303:Adrenal Cortex Diseases / Q000201:enzymology* / Q000235:genetics; D000306:Adrenal Cortex Neoplasms / Q000201:enzymology / Q000235:genetics; D017209:Apoptosis / Q000502:physiology; D015153:Blotting, Western; D002453:Cell Cycle / Q000502:physiology; D048708:Cell Growth Processes / Q000502:physiology; D002460:Cell Line; D000242:Cyclic AMP / Q000378:metabolism; D054756:Cyclic AMP-Dependent Protein Kinase RIalpha Subunit / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D016213:Cyclins / Q000378:metabolism; D004247:DNA / Q000737:chemistry / Q000235:genetics; D050684:E2F Transcription Factors / Q000378:metabolism; D005260:Female; D006801:Humans; D007527:Isoenzymes; D011003:Ploidies; D017354:Point Mutation; D017422:Sequence Analysis, DNA; D014162:Transfection
D054756:Cyclic AMP-Dependent Protein Kinase RIalpha Subunit; D016213:Cyclins; D050684:E2F Transcription Factors; D007527:Isoenzymes; C517834:PRKAR1A protein, human; D004247:DNA; D000242:Cyclic AMP