Immortalization of human prostate epithelial cells by HPV 16 E6/E7 open reading frames.
BACKGROUND
The exact pathogenesis for prostate cancer is not known. Progress 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 immortalization 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 papillomavirus (HPV) type 16 E6 and E7 open reading frames was used to infect primary human prostate epithelial cells. Polymerase chain reaction, followed by Southern hybridization for the HPV 16 E6/E7, Western blot for prostatic acid phosphatase, telomeric repeat amplification protocol assay for telomerase activity, 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 culture for more than 80 successive passages. Normal primary cells failed to proliferate after passage 6. HPr-1 cells bore close resemblance to normal primary prostate epithelial cells, both morphologically and biochemically. However, they possessed telomerase activity and proliferated indefinitely. Cytogenetic analysis of HPr-1 cells revealed a human male karyotype with clonal abnormalities and the appearance of multiple double minutes.


CONCLUSIONS
The HPr-1 cells expressed prostatic acid phosphatase and cytokeratins K8 and K18, proving that they were prostate epithelial cells. They were benign in nude mice tumor formation and soft agar colony formation assay. The HPr-1 cell line is an in vitro representation of early prostate neoplastic progression.
Choo
C K
CK
Department of Pathology, University of Hong Kong, Hong Kong, China. ckchoo@hkucc.hku.hk
Ling
M T
MT
Chan
K W
KW
Tsao
S W
SW
Zheng
Z
Z
Zhang
D
D
Chan
L C
LC
Wong
Y C
YC
D000135:Acid Phosphatase / Q000032:analysis; D000293:Adolescent; D000818:Animals; D002455:Cell Division; D002461:Cell Line, Transformed; D002471:Cell Transformation, Neoplastic; D002869:Chromosome Aberrations; D004847:Epithelial Cells / Q000166:cytology*; D005822:Genetic Vectors; D006801:Humans; D007621:Karyotyping; D007633:Keratins / Q000378:metabolism; D008297:Male; D051379:Mice; D008819:Mice, Nude; D009856:Oncogene Proteins, Viral / Q000235:genetics*; D016366:Open Reading Frames; D027383:Papillomaviridae / Q000235:genetics*; D050725:Papillomavirus E7 Proteins; D011467:Prostate / Q000166:cytology*; D012097:Repressor Proteins; D012190:Retroviridae; D019098:Telomerase / Q000235:genetics; D014183:Transplantation, Heterologous; D014960:X Chromosome; D014998:Y Chromosome
C068651:E6 protein, Human papillomavirus type 16; D009856:Oncogene Proteins, Viral; D050725:Papillomavirus E7 Proteins; D012097:Repressor Proteins; C059731:oncogene protein E7, Human papillomavirus type 16; D007633:Keratins; D019098:Telomerase; D000135:Acid Phosphatase