NUCLEAR CASEIN KINASE-2 (CK-2) ACTIVITY IN HUMAN NORMAL, BENIGN HYPERPLASTIC, AND CANCEROUS PROSTATE

In previous work, we had observed that chromatin-associated nonhistone protein phosphorylation, catalyzed by intrinsic protein kinase reacti on in chromatin preparations from human benign prostatic hyperplasia ( BPH) prostate samples was markedly elevated, compared with the normal prostate chromatin samples [Rayan et al: Cancer Res 45:2277-2282, 1985 ]. The properties of this protein kinase reaction were suggestive of t he involvement of casein kinase(s). By employing the specific syntheti c substrate for casein kinase 2 (CK-2) for assays in cellular fraction s, we have shown that this protein kinase is present in human prostate chromatin. Its activity is increased in BPH chromatin by about 25-fol d, as compared with its activity in the normal prostate chromatin. Thi s suggests that CK-2 is a possible mediator of the enhanced phosphoryl ation of chromosomal proteins in BPH chromatin. By comparison, CK-2 ac tivity in chromatin preparations from prostatic carcinoma samples was markedly less elevated than that of the BPH chromatin. Immunohistochem ical analysis of the enzyme in human frozen sections of prostate tissu e samples showed that the enzyme immunostaining was diffuse in the cyt oplasm, but more intense in the nucleus, especially in the nucleoli. I n general, the staining corresponded with the enzymic data. However, s ections from prostatic carcinoma samples appeared to show differential staining, depending on the Gleason's grade of the sample. The samples with higher Gleason's grade showed less intense immunostain in the nu cleus, compared with samples of lower Gleason's grade. Further, region s of sections in samples with higher Gleason's grade did not show any immunostaining. These differences in the characteristics of CK-2 expre ssion in prostatic carcinoma samples may be potentially significant, b ut need to be evaluated further for their significance to the pathobio logy of prostatic neoplasia. (C) 1994 Wiley-Liss, Inc.