Transfected with a Human Androgen Receptor Complementary Androgen-insensitive Prostate Cancer Cell Line (PC-3) Androgen-induced Inhibition of Cell Proliferation in an

A full length human androgen receptor complementary DNA was in troduced into androgen receptor-negative PC-3 cells to determine if an drogen sensitivity could be established in this cell line and to assess what influence, if any, androgen exposure would have on the growth of these cells. The androgen receptor complementary DNA was inserted into pSG5 in the region controlled by the SV40 promoter. This construct was cotransfected with pSRineo into PC-3 cells and stably transfected cells were selected and screened for the expression of the androgen receptor. Active expression of the receptor was demonstrated by Western blotting using a rabbit anti-androgen receptor antiserum and by pH]methyltrienolone binding to cytosol extracts. Saturation ligand-binding analysis revealed the presence of a single class, high affinity l Aci = 0.122 MM)androgenbinding site in cytosol extracts of transfected cells but not in extracts from mock-transfected cells. In cells expressing the transfected androgen re ceptor, androgen decreased the proliferation rate and cloning efficiency and induced a more differentiated phenotype. These results demonstrate that PC-3 cells have retained the mechanisms required to respond to the activated androgen receptor and that the loss of androgen sensitivity in these cells is due to the lack of functional androgen receptor. This also provides a technique for determining whether androgen-resistant tumor cells contain functional androgen receptors or whether androgen sensitiv ity is due to abnormalities in downstream signaling pathways. The appar ent androgen-induced decreased malignant state of these transfected cells suggests new directions for the treatment of prostate cancer.