LncRNA CCAT1通过结合AR共激活因子p68参与前列腺癌细胞激素非依赖转化及其机制研究

The morbidity and mortality of prostate cancer in China are increasing. Castration resistant prostate cancer (CRPC) is not only a clinical treatment difficulty but also a hotspot in the field of research. Our previous studies showed that the CCAT1 expression was higher in androgen independent cells than androgen dependent cells in prostate cancer. In vitro, CCAT1 not only promoted androgen dependent prostate cancer cells progression but also reduced their sensitivities to androgen deprivation therapy. We also found that CCAT1 interacted with p68 protein which is a co-activator of the androgen receptor (AR) through RNA pulldown. Furthermore, overexpressing CCAT1 increased the expression of the AR downstream genes. Therefore, we hypothesized that CCAT1 was involved in the androgen independence transformation by interacting with AR co-stimulator p68. In this study, the hypothesis will be proven by the following: Evaluate the roles of CCAT1 and its interacting proteins in the diagnosis and prognosis of prostate cancer; Observe the effects of CCAT1 on prostate cancer cells and the efficacy of androgen deprivation therapy; Evaluate the effects of CCAT1 on growth, differentiation and development of human prostate cancer organions; Evaluate the influence of CCAT1 on p68, AR and its signal pathway. If this study can be achieved, it will provides a theoretical basis for the development of effective drugs for CRPC.

去势抵抗性前列腺癌（CRPC）是临床治疗难点也是研究领域的热点。我们前期研究发现非编码RNA CCAT1在前列腺癌激素非依赖组织和细胞中表达升高。体外实验证实CCAT1一方面促进激素依赖前列腺癌细胞恶性进展，另一方面降低其对抗雄激素治疗的敏感性。通过RNA-pulldown实验，我们发现CCAT1可以与雄激素受体AR共激活因子p68结合。并且，过表达CCAT1上调AR下游基因的表达。由此，我们推测CCAT1通过与AR共刺激因子p68结合促进前列腺癌激素非依赖转化。本课题拟从以下方面进行研究：①CCAT1及其相关蛋白对前列腺癌诊断和预后判断的临床价值；②CCAT1对前列腺癌细胞恶性生物学行为和对抗雄激素治疗敏感性的影响；③CCAT1对人前列腺类器官形成、分化以及对抗雄激素治疗的敏感性的影响；④CCAT1对p68、AR及其信号通路的影响。本研究为CRPC有效药物的开发提供理论依据。

前列腺癌的恶性进展是一个连续渐进的多因素、多步骤动态过程，共激活因子、染色质修饰酶以及AR剪切变异体等众多调控分子相互作用，共同促进肿瘤细胞激素依赖状态的转变。深入研究前列腺癌激素依赖状态改变的机制，寻找高效的治疗措施，对于延缓肿瘤恶性进展以及提高患者生存率意义重大。本课题组通过结合激素依赖性前列腺癌（ADPC）患者组织标本、去势抵抗性前列腺癌（CRPC）患者组织标本、远处淋巴结转移患者转移性淋巴结组织标本以及前列腺癌生物学信息数据库发现LncRNA CCAT1在CRPC以及远处淋巴转移组织中显著高表达，并且在CRPC细胞系（PC3、Du145）中表达量显著增加，由此提示CCAT1可能与CRPC的进展密切相关。体内外功能实验研究结果表明CCAT1的高表达能够促进前列腺癌细胞增殖、细胞周期进展，并抑制细胞凋亡。相反，CCAT1表达受到干扰后，前列腺癌细胞的增殖、细胞周期进展受到明显的抑制，凋亡细胞比例增高。结合CCAT1表达下降后相关信号通路的改变，可以得出结论，CCAT1在前列腺癌中发挥了促癌基因的作用。CCAT1可与miR-28-5p直接结合，逆转miR-28-5p的肿瘤抑制作用，从而发挥促进前列腺癌细胞增殖的生物学功能。进一步的研究表明在前列腺癌细胞核中，CCAT1可以招募p68与AR定位于AR通路靶基因PSA的不同片段上，提高AR信号通路基因PSA、hNKX3.1以及AR调控的去势抵抗基因UBE2C的表达水平，异常激活AR信号通路，促进前列腺癌的恶性进展与CRPC的转化，为去势抵抗性前列腺癌的诊治提供理论依据。