Immortalization of human prostate epithelial cells by HPV 16 E6/E7 open reading frames

BACKGROUND. The exact pathogenesis for prostate cancer is not known. Progre ss made in prostate cancer research has been slow, largely due to the lack of suitable in vitro models. Here, we report our work on the immortalizatio n of a human prostate epithelial cell line and show that it can be used as a model to study prostate tumorigenesis. METHODS. Replication-defective retrovirus harboring the human papillomaviru s (HPV) type 16 E6 and E7 open reading frames was used to infect primary hu man prostate epithelial cells. Polymerase chain reaction, followed by South ern hybridization for the HPV 16 E6/E7, Western blot for prostatic acid pho sphatase, telomeric repeat amplification protocol assay for telomerase acti vity, two-dimensional gels for cytokeratins, and cytogenetic analysis were undertaken to characterized the infected cells. RESULTS. The retrovirus-infected cell line, HPr-1, continued to grow in cul ture for more than 80 successive passages. Normal primary cells failed to p roliferate after passage 6. HPr-1 cells bore close resemblance to normal pr imary prostate epithelial cells, both morphologically and biochemically. Ho wever, they possessed telomerase activity and proliferated indefinitely. Cy togenetic analysis of HPr-1 cells revealed a human male karyotype with clon al abnormalities and the appearance of multiple double minutes. CONCLUSIONS. The HPr-1 cells expressed prostatic acid phosphatase and cytok eratins K8 and K18, proving that they were prostate epithelial cells. They were benign in nude mice tumor formation and soft agar colony formation ass ay. The HPr-1 cell line is an in vitro representation of early prostate neo plastic progression. (C) 1999 Wiley-Liss, Inc.