Objective: To investigate the effect of dihydrotestosterone (DHT) on the gene transcriptions and expressions of Smad3 and Smad4 in androgen dependent prostate cancer cell line LNCaP, and whether this effect can be suppressed by the androgen receptor inhibitor flutamide.
Methods: The androgen dependent prostate cancer cell line LNCaP was cultured in RPMI 1640 medium and treated with different concentrations of DHT(2, 10, 50 nmol/L) and flutamide (100 nmol/L). Quantitative reverse transcription PCR (RT-PCR) was used to detect the mRNAs of Smad3 and Smad4. The expressions of Smad3 and Smad4 protein were detected by Western blot assay.
Results: Compared with the control group without any DHT or flutamide, higher concentration(10, 50 nmol/L) of DHT enhanced the transcription of Smad3 mRNA (P <0.05). Serial concentrations of DHT increased the expression of Smad3 protein(P < 0.05). Flutamide inhibited the up-regulation of both Smad3 mRNA transcription and expression significantly (P <0.05). 10 nmol/L DHT significantly suppressed the transcription of Smad4 (P <0.05). There was considerable suppressions of Smad4 expression at the presence of DHT in different concentrations (P < 0.05). And the degree of this suppression was more significant than that of DHT on Smad4 mRNA transcription. Flutamide inhibited the suppressive effects of DHT on both Smad4 mRNA transcription and expression.
Conclusion: DHT can enhance the transcription and expression of Smad3, while it decreases the transcription and expression of Smad4 in LNCaP cell line. There is a possible crosstalk between the AR signal and TGF-beta signal passways at the level of Smads.