Effects of WNT/β-catenin pathway activation on signaling through T-cell factor and androgen receptor in prostate cancer cell lines
- M. V. Cronauer
- W. A. Schulz
- R. Ackermann
- M. Burchardt
- Corresponding author:
Published online on: Friday, April 1, 2005
Dysregulation of the WNT/β-catenin pathway is thought to contribute to prostate cancer progression. Mutations of β-catenin occurring in 5-7% of advanced prostate cancers may act by stimulating TCF-dependent and/or androgen receptor (AR)-dependent transcription. Using a reporter gene approach we found overexpressed mutated β-catenin to enhance AR-regulated probasin-promoter activity in the AR-positive prostate cancer cell line 22Rv1, particularly at low androgen levels. In 22Rv1 cells mutated β-catenin was able to stimulate TCF-dependent transcription but was unable to do so in LNCaP cells where it activates the AR. Since β-catenin mutations are rare in vivo, we studied further possible routes of WNT-pathway modulation. Higher concentrations of LiCl, a GSK3β-inhibitor, were required to activate TCF-dependent rather than AR-dependent reporter constructs. In 22Rv1 overexpression of E-cadherin repressed androgen-dependent transcription, but did not inhibit transcription of TCF-dependent reporter genes as in bladder cancer cell lines. Interestingly, Wnt-3a stimulated proliferation selectively in the AR-positive prostate cancer cell lines 22Rv1 and LNCaP, even though TCF-dependent reporter gene transcription was not induced in LNCaP cells. In summary, the data from our study support the idea that activation of WNT/β-catenin signaling in AR-positive prostate cancer cells may predominantly act through AR-dependent mechanisms rather than classical TCF-dependent mechanisms.