Comparison of soluble protein kinases from normal rat prostates and prostatic Dunning tumors

The photoaffinity labeling of the regulatory subunits of adenosine cyclic 3':5'-monophosphate-dependent soluble protein kinases with an adenosine cyclic 3':5' monophosphate analogue, 8-azidoadenosine cyclic 3':5'-monophosphate (8-N3-cAMP) was compared in normal prostates and prostatic (Dunning) tumors. Marked differences in the proportions of photoincorporation of 8-N3-[32P]cAMP into the regulatory subunit of type I (RI) and type II (RII) protein kinases and the proteolytic fragment of these regulatory subunits (Rpf) were observed in normal prostate (ventral prostate versus dorsolateral prostate) and Dunning prostatic tumors [hormone-dependent (R-3327-H) versus hormone-independent (R-3327-HI) or anaplastic (R-3327-AT) tumors]. The proportion of 8-N3-[32P]cAMP photoincorporation into RII versus RI was 2-fold higher in the dorsolateral prostate than that observed in the ventral prostate, whereas the ratio of photoincorporation into RI or Rpf was comparable between these two tissues. Comparison between tumor tissues revealed that the proportion of photoincorporation of 8-N3-[32P]cAMP into RII versus RI was 4.2-fold higher in hormone-dependent than in hormone-independent or anaplastic tumors, whereas the ratio of photoincorporation into RI versus Rpf in the former was only 6 to 7% that found in the latter. Since Dunning hormone-dependent and hormone-independent tumors have similar morphology, the present photoaffinity labeling of these regulatory subunits of soluble protein kinases provides a sensitive method (4 mg tissue per assay) to distinguish these prostatic tumors of different hormonal dependency.