GABARAPL1抑制前列腺癌侵袭、转移的分子机制研究

The lethality of prostate cancer (PCa) is attributable to metastasis. There is incontrovertible evidence that PI3K/AKT and Androgen receptor (AR) signal pathway plays a critical role in PCa progression and metastasis. However, the molecular mechanisms for the contribution of PI3K/AKT and AR in PCa metastasis remain elusive. Employing Decode lentiviruses encoding the entire human genomic shRNA library and subsequent in vivo studies, we have recently identified GABA(A) receptor-associated protein like 1 (Gabarapl1) as a potential PCa metastasis suppressor. Knockdown of Gabarapl1 promoted metastatic potential of PCa LNCaP cells in vitro. Further, RNA microarray analysis revealed that Gabarapl1 was significantly down-regulated in PCa tissues compared with normal prostate tissue samples and Kaplan-Meier curves analysis of metastatic tissue samples from PCa patients showed correlation of low Gabarapl1 expression with more rapid development of metastases, indicating an important role of Gabarapl1 in PCa metastasis. AKT activation resulted in the downregulation of Gabarapl1. In addition, we found that Gabarapl1 also directly binds to AR. Thus, we hypothesize that negative regulation of Gabarapl1 signaling by PI3K/AKT or AR is a major contributor for PCa progression and metastasis. The goals of our research are to elucidate the molecular mechanisms of Gabarapl1 in regulating PCa progression and metastasis, and to explore the diagnostic and therapeutic applications of Gabarapl1 in PCa metastasis. Results from the proposed studies will provide novel insights into the role of Gabarapl1 in regulating PCa metastasis and the prognostic and diagnostic value of Gabarapl1 in PCa metastasis. Furthermore, our research will facilitate the development of novel strategies to prevent, diagnose, or treat the deadly metastatic PCa.

目前，转移仍是前列腺癌死亡的首要原因。PI3K/AKT与雄激素受体（AR）通路的相互作用在前列腺癌进展、转移中起关键作用。因此，加深理解这些信号通路的分子机制对提高病人生存率至关重要。我们利用针对人类全基因组的shRNA库转染的前列腺癌细胞原位前列腺癌裸鼠模型，从体内筛选与转移有关的基因，发现Gabarapl1是一个新的前列腺癌转移抑制基因。AKT的激活导致Gabarapl1表达降低，且Gabarapl1能通过直接与AR结合来抑制其活性。因此，我们推断Gabarapl1可能通过抑制PI3K/AKT和AR信号途径来发挥作用。本项目拟在前期研究基础上，进一步探讨Gabarapl1在AR与PI3K/AKT信号通路起的作用，明确Gabarapl1抑制前列腺癌癌转移的分子机制。本项目旨在揭示Gabarapl1在前列腺癌进展、转移中的作用机制，并发现新的肿瘤治疗途径。

尽管雄激素阻断疗法早期疗效明显，但大部分前列腺癌病人仍不可避免地发展成去势抵抗性前列腺癌，最终死于转移。研究显示大部分去势抵抗性前列腺癌不仅通过蛋白激酶B（AKT）这些新通路，且仍依赖雄性激素受体（AR）信号通路，二者之间的相互作用共同促进去势抵抗性前列腺癌进展、转移。因此，加深理解这些信号通路的相互作用分子机制对提高病人生存率至关重要。本项目拟探讨γ氨基丁酸A受体相关类蛋白1 （gamma-aminobutyric acid (GABA) A receptor-associated protein-like 1 (GABARAP1)）在AR与AKT信号通路中所起作用，旨在揭示GABARAPL1在前列腺癌进展、转移中的作用机制，并发现新的肿瘤治疗途径。我们发现siRNA敲减前列腺癌细胞内的GABARAPL1后，导致细胞侵袭性增强。反之，过表达GABARAPL1抑制前列腺细胞的侵袭。我们还发现siRNA敲减前列腺癌细胞内的FOXO蛋白后，导致细胞侵袭性增强和GABARAPL1表达降低；与此相反，前列腺癌细胞转染持续激活的AKT后，导致FOXO蛋白活性减弱，GABARAPL1表达降低和前列腺癌细胞侵袭性增强。这些研究表明AKT可能通过抑制FOXO蛋白及其调控的下游基因GABARAPL1来促进前列腺癌的转移。进一步我们发现GABARAPL1 通过蛋白之间的相互作用调控全长和突变体AR的转录活性以及AR核转位。我们的研究表明GABARAPL1是AKT和AR相互作用网络中的一个关键调控因子，是前列腺癌去激素抵抗治疗的一个潜在靶向分子。总之，通过这些研究我们将揭示前列腺癌转移的分子机制并研发新的前列腺癌精准治疗途径。