去势抵抗性前列腺癌干细胞的鉴定及其干性调控的分子机制研究

The morbidity and mortality rate of prostate cancer (PCa) has been increasing in China. Most patients with advanced PCa eventually fail to respond to androgen-deprivation therapy due to the development of castration-resistant prostate cancer (CRPC) that is lethal and incurable. So far, the cellular and molecular mechanisms underlying CRPC are not completely understood. In our earlier study, we found that PCa cells bearing an ALDH+CD44+α2β1+ (Triple Marker+, TM+) phenotype in LAPC9 CRPC xenografts have both tumor-regenerating and colony-initiating abilities. Subsequent investigations have suggested that SOX9 is highly expressed in TM+ PCa cells, and knocking down SOX9 expression in TM+ PCa cells inhibits their colony formation. Thus, based on our preliminary data, our central hypothesis is that TM+ PCa cells are a population of cancer stem cells in CRPC, and SOX9 acts as the key regulator in manipulating CSC capacities and castration resistant propensity of TM+ PCa cells. To test our hypothesis, we aim to achieve the following goals: 1) To correlate TM+ PCa cell abundance with PCa malignant progression; 2) To systematically examine the CSC activities of TM+ PCa cells in androgen-deprived conditions; 3) To test the hypothesis that SOX9 represents a ‘master’ regulator in the regulation of the CSC properties of TM+ PCa cells in CRPC emergence. Completing the current project herein will greatly impact our understanding of PCa biology, and lay a solid foundation for the development of novel therapeutics to specifically target CSCs in CRPC.

去势抵抗性前列腺癌 (CRPC)是导致前列腺癌(PCa)患者去势(雄性激素剥夺)治疗失败，并引发死亡的主要原因。CRPC是临床治疗的难点和研究热点，其细胞来源和分子机制目前尚不清楚。申请人前期研究发现，以ALDH+CD44+α2β1+(Triple Marker+, TM+)为表型的PCa细胞，在去势环境下成瘤性及球体形成能力增强；进一步筛选发现TM+细胞高表达SOX9，且下调SOX9会降低TM+细胞的球体形成能力。本课题将在前期工作基础上，鉴定TM+细胞是否为CRPC的一类癌干细胞，并阐明其干细胞特性(干性)的调控机制。具体包括：研究TM+细胞的表达量与PCa恶性进展的关联性；评估体内、外去势条件下TM+细胞的癌干细胞特性；阐明SOX9是否是调控TM+细胞在CRPC中发挥干性的关键因子。本课题拟通过鉴定CRPC的癌干细胞并阐明其相关调控机制，为诊断和靶向治疗CRPC提供新思路。

去势抵抗性前列腺癌(CRPC)临床难以治愈，是晚期前列腺癌(PCa)患者死亡的主要原因，其细胞来源及分子发病机制目前尚不清楚。项目研究发现：1）部分临床未经激素治疗的PCa样本中包含以ALDH+CD44+α2β1+(Triple Marker+, TM+)为表型的PCa细胞，且TM+细胞的表达量与PCa恶性进展呈正相关趋势；2）在LAPC9 CRPC移植瘤模型中，体外和体内实验证实LAPC9 CRPC TM+细胞在去势条件下具有癌干细胞特性；3）在CRPC细胞系PC3及Du145模型中，我们验证了以ALDH+CD44+ (DP)为表型的PCa细胞在去势环境下具有癌干细胞特点；4）我们发现敲减SOX9会降低LAPC9 CRPC TM+细胞体外球体形成能力及体内成瘤能力；全基因组第二代测序(RNA-Sequencing)及详细的生物信息学分析显示: LAPC9 CRPC细胞中富集癌干细胞相关通路及因子，如‘Nanog相关通路’、‘Wnt/β-catenin通路’、‘BCL-2’等。结合前期文献报道，我们结果提示Nanog可能是SOX9潜在的下游因子，但Nanog如何在SOX9/β-catenin信号通路下游其重要作用尚需深入研究；5）在PC3及Du145模型中，第二代测序、生物信息学分析及功能学验证均提示SOX2是CRPC细胞发挥癌干细胞特性的重要因子。本研究鉴定了CRPC的癌干细胞群体并发现SOX家族因子参与相关调控机制，为诊断和靶向治疗CRPC提供新策略。