Real-time imaging analysis of androgen receptor function in hormone refractory Prostate cancer

雄激素通过雄激素受体(AIR)这一核受体超家族成员的作用来促进前列腺癌的细胞增殖。在前列腺癌LNCaP细胞系中发现AR基因的一个点突变(T877A)，该突变可能与低浓度雄激素过敏有关。本研究通过将绿色荧光蛋白(GFP)标记到受体上，检测了不同浓度的AR和AR(T877A)在活体前列腺癌和非前列腺癌细胞系中的转运。在一个非前列腺癌细胞系中，COS-1、野生型AR和突变型AR在缺乏配体的情况下存在差异定位，AR完全定位于胞浆，而AR(T877A)定位于胞浆和胞核。而在LNCaP中，AR和AR(T877A)均定位于胞浆和胞核。加入配基后，定位于细胞质的两种受体均移位到细胞核中。此外，在低浓度雄激素存在下，LNCaP细胞中观察到易位，而COS-1细胞中未观察到易位，野生型AR和突变型AR的易位模式没有显著差异。这些结果表明，AR的过敏性可能受到细胞内因素的影响，如辅因子和与另一条信号通路的串扰，而不是AR基因的突变。绿色荧光蛋白实时成像技术是研究激素难治性前列腺癌分子机制的有效工具。

Androgen has been shown to promote cell proliferation of prostate cancer through the action of androgen receptor (AIR) that is a number of the nuclear receptor superfamily. In a prostate cancer cell line, LNCaP, a point mutation (T877A) is found in AR gene, and it has been supposed that this mutation would be involved in hypersensitivity for low concentration of androgen. In the present study, trafficking of AR and AR(T877A) in living prostate and non-prostate cancer cell lines under various concentration of the ligands was examined by tagging green fluorescent protein (GFP) to the receptors. In a non-prostate cancer cell line, COS-1,wild type AR and mutant AR were differentially localized in the absence of ligand ; AR was completely localized in cytoplasm, but AR(T877A) was localized in cytoplasm and nucleus. In contrast, both AR and AR(T877A) were localized in cytoplasm and nucleus in LNCaP. Upon the addition of the ligand, both type of the receptors that localized in the cytoplasm were translocated into the nucleus in the both cell lines. Moreover, in the presence of low concentration of androgen, the translocation was observed in LNCaP cells, but not in COS-1 cells, and there was no significant difference in the translocation pattern between wild type AR and mutant AR. These results suggest that hypersensitivity of AR may be affected by intracellular factors, such as co-factors and crosstalk with another signal pathway, more than the mutation of AR gene. Real-time imaging with GFP was a promising tool for the investigation of molecular mechanism of hormone refractory appearance prostate cancer.