雄激素受体在膀胱癌进展中对GATA3的调控机制研究

Bladder cancer is the most common genitourinary malignancy in China, and is also costly cancer to treat in the US Medicare population, mounting evidence supports that Androgen Receptor (AR) plays an important role in promoting bladder cancer development and progression. However, the underlying mechanisms of androgen receptor signals regulating bladder cancer progression are still far from fully characterized. Transcription factor GATA binding protein 3 (GATA3) has recently been recognized as one of urothelial markers. In our preliminary work, we are the first to demonstrate that androgen treatments in SVHUC-AR decreased GATA3 expression, which was restored by anti-androgens. Further study in bladder cancer cell lines indicated loss of GATA3 correlated with promotion of cell migration and invasion. In addition, we also found there were significant correlations of GATA3 expression with the expression of AR in human bladder cancer tissues. Thus, it appeared that the stimulatory effect of AR in bladder cancer may be related to GATA3. In this research project, by using gene transfection、RNA interference and mouse models, we will investigate the mechanism of androgen receptor regulating GATA3 in bladder cancer cell lines, further proof whether stimulatory effect of AR in bladder cancer is GATA3-dependent or not in vitro and in vivo. In summary, this research project may enhance the understanding of the mechanism of AR promoting bladder cancer progression, provide not only a new target for prevention and treatment of bladder cancer, but also the foundation for bladder cancer therapy with anti-androgens.

膀胱癌是我国最常见的泌尿系恶性肿瘤，大量研究已证实雄激素受体（Androgen Receptor，AR）在膀胱癌发生发展中发挥重要作用，然而，其中的分子机制尚未完全阐明。GATA3是近年来发现的尿路上皮标记物之一，申请者前期研究首先发现在AR阳性的良性尿路上皮细胞中雄激素可下调GATA3的表达，进一步研究表明GATA3能抑制膀胱癌细胞迁移、浸润。因此，推测AR在膀胱癌中的作用可能与GATA3相关。本项目拟应用RNA干扰、基因转染及裸鼠模型等技术，研究AR在膀胱癌进展中对GATA3的表达转录调控机制，同时明确AR是否通过靶基因GATA3促进膀胱癌的进展。本项目有望为筛选对抗雄激素治疗敏感的膀胱癌患者和开辟新的靶向治疗药物提供理论依据。

大量的研究证明雄激素受体（AR）在膀胱癌发生发展中发挥重要作用，其调控过程涉及复杂的分子机制。GATA3也被证实与多种恶性肿瘤分级及预后密切相关，是目前研究的热点，但其与AR的相关性尚未阐明。课题组成员首次发现在AR表达阳性的良性尿路上皮细胞中，雄激素可以明显下调GATA3的表达水平。进一步研究表明GATA3可抑制尿路上皮细胞SVHUC的恶性转化，有利于抑制膀胱癌的发生，还可抑制多种膀胱尿路上皮癌细胞株的侵袭和转移。.本课题组通过挖掘TCGA数据库上膀胱癌组织中GATA3的RNA测序及蛋白芯片数据，发现GATA3表达的高低与病人预后、肿瘤分期分级、侵袭转移以及化疗预后均有显著性相关，且与上皮间质化（EMT）以及侵袭转移的诸多基因呈负相关。进一步研究表明GATA3可通过调控miRNA-29b-3p的转录水平抑制膀胱癌细胞侵袭转移及EMT。本研究亦证实GATA3能够抑制膀胱癌细胞对化疗药多柔比星和顺铂的耐药性。随后课题组采用RNA干扰技术下调EMT过程中的关键转录因子Twist的表达后，发现EMT相关蛋白E-Cadherin表达上调，N-Cadherin、Twist以及Vimentin的表达均下调，同时膀胱癌细胞对化疗药物的敏感性增加。由此说明GATA3是由miRNA-29b-3p介导抑制EMT，从而降低膀胱癌细胞化疗耐药性。.综上所述，本课题结合当今肿瘤机制研究热点，证实AR及GATA3在膀胱癌发生发展中发挥重要作用，揭示了膀胱癌化疗耐药性的新机制，为临床寻求膀胱癌新的治疗方法提供了实验基础和理论依据。