Androgen dependent regulation of protein kinase A subunits in prostate cancer cells

Neuroendocrine (NE) cells may play a role in prostate cancer progression. Both androgen deprivation and cAMP are well known inducers of NE differentiation (NED) in the prostate. Gene-expression profiling of LNCaP cells, incubated in androgen stripped medium, showed that the Cβ isoform of PKA is up-regulated during NE differentiation. Furthermore, by using semi-quantitative RT-PCR and immunoblotting analysis, we observed that the Cβ splice variants are differentially regulated during this process. Whereas the Cβ2 splice variant is down-regulated in growth arrested LNCaP cells, the Cβ1, Cβ3 and Cβ4 variants, as well as the RIIβ subunit of PKA, are induced in NE-like LNCaP cells. The opposite effect of Cβ expression could be mimicked by androgen stimulation, implying the Cβ gene of PKA as a putative new target gene for the androgen receptor in prostate cancer. Moreover, to investigate expression of PKA subunits during prostate cancer progression, we did immunoblotting of several prostatic cell lines and normal and tumor tissue from prostate cancer patients. Interestingly, multiple Cβ subunits were also observed in human prostate specimens, and the Cβ2 variant was up-regulated in tumor cells. In conclusion, it seems that the Cβ isoforms play different roles in proliferation and differentiation and could therefore be potential markers for prostate cancer progression.