Molecular genetic analyses of the TMPRSS2-ERG and TMPRSS2-ETV1 gene fusions in 50 cases of prostate cancer.

Recently, gene fusions between the androgen responsive gene TMPRSS2 and members of the ETS-family of DNA-binding transcription factor genes were found in prostate cancer. Recurrent fusions were identified between the 5'-noncoding region of TMPRSS2 and ERG, or less frequently ETV1 or ETV4, resulting in overexpression of normal or truncated ETS-proteins. Herein, we have analyzed a series of 50 prostate cancer samples for expression of TPRSS2-ERG and TMPRSS2-ETV1 fusion transcripts. RT-PCR analysis revealed TMPRSS2-ERG fusion transcripts in 18 of the 50 tumors (36%). None of the tumors expressed a TMPRSS2-ETV1 fusion. Our findings show that the TMPRSS2-ERG fusion is common in prostate cancer and that the related TMPRSS2-ETV1 fusion is very rare. However, the frequency of ERG-fusions in the present study is somewhat lower than previously observed, indicating heterogeneity with regard to expression of ETS-gene fusions in subsets of prostate cancers. Moreover, clinical follow-up studies showed a clear tendency that fusion-positive tumors were associated with lower Gleason grade and better survival than fusion-negative tumors. Our findings suggest that ERG gene fusions might be of prognostic significance in prostate cancer.

Neutralizing VEGF bioactivity with a soluble chimeric VEGF-receptor protein flt(1-3)IgG inhibits testosterone-stimulated prostate growth in castrated mice.

BACKGROUND: Recent studies show that testosterone-stimulated growth of the glandular tissue in the ventral prostate in adult castrated rats is preceded by increased epithelial VEGF synthesis, endothelial cell proliferation, vascular growth, and increased blood flow. These observations suggest that testosterone-stimulated prostate growth could be angiogenesis dependent, and that VEGF could play a central role in this process. METHODS: Adult male mice were castrated and after 1 week treated with testosterone and vehicle, or with testosterone and a soluble chimeric VEGF-receptor flt(1-3)IgG protein. RESULTS: Treatment with testosterone markedly increased endothelial cell proliferation, vascular volume, and organ weight in the ventral prostate lobe in the vehicle groups, but these responses were inhibited but not fully prevented by anti-VEGF treatment. The testosterone-stimulated increase in epithelial cell proliferation was unaffected by flt(1-3)IgG, but endothelial and epithelial cell apoptosis were increased in the anti-VEGF compared to the vehicle-treated groups. CONCLUSIONS: This study suggests that testosterone stimulates vascular growth in the ventral prostate lobe indirectly by increasing epithelial VEGF synthesis and that this is a necessary component in testosterone-stimulated prostate growth.

Endothelial cell proliferation in male reproductive organs of adult rat is high and regulated by testicular factors.

Endothelial cells in the intact adult are, apart from those in the female reproductive organs, believed to be quiescent. Systematic examination of endothelial cell proliferation in male reproductive organs has not been performed and was therefore the aim of the present study. Intact adult rats were either pulse labeled or long-term labeled with bromodeoxyuridine to label proliferating cells. The roles of Leydig cells and testosterone were examined after castration or treatment with the Leydig cell toxin ethane dimethane sulfonate (EDS) and testosterone substitution. After perfusion fixation, all blood vessels remained open and were easily identified. In all male reproductive organs studied, particularly in the testis and epididymis, endothelial cell proliferation was considerably higher than in other tissues such as the liver, brain, and muscle. Proliferating endothelial cells were observed in all types of blood vessels in male reproductive organs, but other characteristics of new blood vessel formation were not seen. High endothelial cell proliferation may reflect a continuous high turnover of endothelial cells rather than classical angiogenesis. In the epididymis, the ventral and dorsolateral prostate lobes, and the seminal vesicles, endothelial cell proliferation decreased after testosterone withdrawal and increased following testosterone treatment. In the testis, endothelial cell proliferation was decreased after Leydig cell depletion but remained low after testosterone substitution. High, hormonally regulated endothelial cell proliferation is not unique to the female but is also seen in the male reproductive organs.