Ala99ser mutation in RI alpha regulatory subunit of protein kinase A causes reduced kinase activation by cAMP and arrest of hormone-dependent breast cancer cell growth.
Expression of the RIalpha regulatory subunit of protein kinase A type I is increased in human cancer cell lines, in primary tumors, in cells after transformation, and in cells upon stimulation of growth. Ala99 (the pseudophosphorylation site) of human RIalpha was replaced with Ser (RIalpha-p) for the structure-function analysis of RIalpha. MCF-7 hormone-dependent breast cancer cells were transfected with an expression vector for the wild-type RIalpha or mutant RIalpha-p. Overexpression of RIalpha-P resulted in suppression of protein kinase A type II, the isozyme of type I kinase, production of kinase exhibiting reduced cAMP activation, and inhibition of cell growth showing an increase in G0/G1 phase of the cell cycle and apoptosis. The wild-type RIalpha overexpression had no effect on protein kinase A isozyme distribution or cell growth. Overexpression of protein kinase A type II regulatory subunit, RIIbeta, suppressed RIalpha and protein kinase A type I and inhibited cell growth. These results show that the growth of hormone-dependent breast cancer cells is dependent on the functional protein kinase A type I.
Cellular Biochemistry Section, Laboratory of Tumor Immunology and Biology, National Cancer Institute, Bethesda, MD 20892-1750, USA.
G R
GR
Lee
S N
SN
Kim
K
K
Noguchi
S D
SD
Park
S H
SH
Hong
Y S
YS
Cho-Chung
D000409:Alanine / Q000235:genetics*; D019943:Amino Acid Substitution / Q000235:genetics; D017209:Apoptosis / Q000235:genetics; D001943:Breast Neoplasms / Q000235:genetics* / Q000473:pathology*; D002455:Cell Division / Q000235:genetics; D000242:Cyclic AMP / Q000378:metabolism / Q000502:physiology*; D054756:Cyclic AMP-Dependent Protein Kinase RIalpha Subunit; D054746:Cyclic AMP-Dependent Protein Kinase Type II; D017868:Cyclic AMP-Dependent Protein Kinases / Q000235:genetics*; D004789:Enzyme Activation / Q000235:genetics; D006801:Humans; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D016297:Mutagenesis, Site-Directed / Q000502:physiology; D009376:Neoplasms, Hormone-Dependent / Q000235:genetics* / Q000473:pathology*; D012694:Serine / Q000235:genetics*; D014162:Transfection; D014407:Tumor Cells, Cultured
D054756:Cyclic AMP-Dependent Protein Kinase RIalpha Subunit; D007527:Isoenzymes; C517834:PRKAR1A protein, human; D012694:Serine; D000242:Cyclic AMP; D054746:Cyclic AMP-Dependent Protein Kinase Type II; D017868:Cyclic AMP-Dependent Protein Kinases; D000409:Alanine