Molecular correlates of bcl-2-enhanced growth following androgen-ablation in prostate carcinoma cells in vivo.
Androgen-independent growth of prostate cancer is correlated with expression of bcl-2. The impact of bcl-2 expression on the growth of prostate cancer cells following androgen ablation, was examined in the androgen-sensitive prostatic carcinoma cell line, LNCaP. Vector control and bcl-2 expressing LNCaP cells were grown subcutaneously in male nude mice. Tumor volume, apoptosis, and proliferation were assessed following castration. The levels of c-myc, p53, p21, bax, and bcl-2 protein were assessed by Western blotting. Bcl-2 expressing tumors exhibited a significant augmentation in growth compared to controls (p 0.01). No difference in the spontaneous rate of proliferation was observed between bcl-2 and control tumors, however, bcl-2 expressing tumors exhibited lower rates of apoptosis. Following orchiectomy the apoptotic index remained significantly lower in bcl-2 expressing tumors (p 0.002 at day 3). The proliferative index was maintained in bcl-2 expressing, but not control tumors following castration. This resulted in a significant growth advantage in bcl-2 tumors subsequent to androgen ablation (p 0.001). These changes were accompanied by alterations in the levels of gene products known to regulate the cell cycle and/or apoptosis. These results emphasize the significance of bcl-2 expression during prostate cancer progression and suggest possible mechanisms for the acquisition of androgen-independent tumor growth.
Beham
A W
AW
Department of Molecular Pathology, The University of Texas M.D. Anderson Cancer Center, Houston, TX 77030, USA.
Sarkiss
M
M
Brisbay
S
S
Tu
S M
SM
von Eschenbach
A C
AC
McDonnell
T J
TJ
D000728:Androgens / Q000502:physiology*; D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western; D002369:Castration; D002455:Cell Division; D004274:DNA, Recombinant / Q000235:genetics; D005822:Genetic Vectors; D006801:Humans; D008297:Male; D051379:Mice; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D011471:Prostatic Neoplasms / Q000378:metabolism / Q000473:pathology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism*; D016271:Proto-Oncogene Proteins c-myc / Q000378:metabolism; D014183:Transplantation, Heterologous; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
D000728:Androgens; D004274:DNA, Recombinant; D019253:Proto-Oncogene Proteins c-bcl-2; D016271:Proto-Oncogene Proteins c-myc; D016159:Tumor Suppressor Protein p53