The impact of graphene oxide on androgen receptor signalling in prostate cancer cells

Androgen receptor (AR) signalling is triggered by androgens that have lipophilic nature. Since it was indicated that graphene oxide (GO) might facilitate passive diffusion of lipophilic compounds probably via Trojan horse-like mechanism, we tested the hypothesis if this suggestion would apply for androgens as well. Thus, we investigated if GO affects dihydrotestosterone (DHT)-triggered signalling of AR in two prostate cancer-derived cell lines, 22Rv1 and LNCaP. These cell lines differ in number of AR variants, i.e. there are two variants in 22Rv1 cells (full length and truncated) but only one in LNCaP cells (full length). Graphene oxide had no effect on basal luciferase activity but significantly decreased DHT-inducible AR-dependent luciferase activity in stably transfected cells. In 22Rv1 cells, it induced concentration-dependent decrease of DHT-inducible KLK3 mRNA and PSA protein after 24 h. While there was no effect on UBE2C mRNA (regulated by truncated variant), there was synergistic effect of DHT and GO on UBE2C protein level. Translocation of full-length AR (AR-FL) was potentiated by GO in the presence of DHT in 22Rv1 cells but it was suppressed in LNCaP cells. DHT-stimulated enrichment of AR-FL on KLK3 promoter was not significantly affected by GO in any tested cell line neither was KLK3 mRNA at 4 h of incubation. In conclusion, GO affects DHT-triggered signalling in both types of cells in similar manner, but ligand-triggered redistribution of AR-FL is affected differently. One of the reasons may be the presence of truncated variant of androgen receptor.