对引发前列腺癌转移的起源细胞的鉴定及HOXB9调控其转移活性的分子机制

Prostate cancer (PCa) is a leading male malignancy in urogenital system, with an increasingly higher incidence in China. The worst outcome for PCa patients, whether treated or not, is development of metastasis. So far, little is known about the molecular mechanism underlying metastasis and cells-of-origin for PCa metastasis. PCa patients can be grouped into two types: one group harboring indolent tumors that rarely or only slowly progress whereas the other having aggressive primary tumors that quickly progress and disseminate. It remains to be elucidated how the primary tumor microenvironment affects the metastatic propensity of PCa cells. The current NSFC application attempts to address the aforementioned questions. To start understanding how a "pro-metastasis" microenvironment may facilitate PCa metastasis, we took advantage of the long-observed phenomenon that human cancer cells, when orthotopically implanted in immunodeficient mice, show more extensive and widespread metastasis than when ectopically implanted. To this end, we implanted multiple GFP or RFP tagged PCa cells either ectopically in the subcutis (s.c) or orthotopically in the dorsal prostate (DP) of NOD/SCID mice. We then uncovered the DP and s.c prostate tumors and performed comparative genome-wide transcriptome analysis, which revealed an upregulation of 602 genes in the DP (i.e., metastasis-prone) tumors that fall into distinct, very informative functional classes. One class of genes, about 50 (around 8% of total), is well-known stem cell/cancer stem cell (CSC) regulators and/or markers. Preliminary functional studies on some of the genes implicate their importance in regulating PCa metastasis and in conferring properties of metastatic prostate CSCs (mPCSCs). Meta-analysis of the upregulated genes identified the " mPCSCs' gene signature " that correlates with the propensity of recurrence in patients. Based on the preliminary data, the current NSFC grant application aims to go further to achieve the following 3 goals: 1) To perform further functional studies on the genes upregulated in the DP human prostate tumors; 2) To test the hypothesis that the DP human PCa cells overexpressing CSC markers possess mPCSC properties; and 3) To test the hypothesis that HOXB9 represents a 'master' regulator of mPCSCs and PCa metastasis. By unveiling the gene signature, identification features and regulating mechanisms of mPCSCs, we finally aim to verify our central hypothesis that mPCSCs are cells-of-origin for PCa metastasis and HOXB9 acts as a key regulator in manipulating metastatic propensity of mPCSCs. The current project should greatly impact our understanding of PCa biology by identifying mPCSCs and elucidating their gene expression profiles and functional requirements. The outcome should also impact PCa patients by identifying novel therapeutic targets for PCa metastasis, the ultimate killer of patients.

前列腺癌(prostate cancer,PCa)是男性泌尿生殖系统常见的恶性肿瘤，在中国的发病率逐年升高，患者多死于癌转移。目前，对于PCa转移的分子机制及引发转移的细胞起源不甚了解。本研究所通过预实验发现在PCa中存在具有高转移活性的PCa干细胞(metastatic prostate cancer stem cells,mPCSCs)，并通过微阵列分析发现了与转移相关的分子。基于此，拟进行以下研究：1)论证不同部位种植瘤转移活性的差异并微阵列分析相应转录谱，鉴定与转移活性相关的特征性基因；2)论证过表达癌干细胞标志物的人类癌细胞具有mPCSCs的行为特性；3)论证HOXB9是调控mPCSCs转移活性的关键因子。通过阐释mPCSCs的基因特征、身份鉴定及受控机制，进而论证mPCSCs是引发PCa转移的起源细胞及其受HOXB9调控的机制，从而为设计针对mPCSCs的靶向疗法奠定理论基础。

肿瘤内复杂的微环境，以及无时不刻不在发生的遗传学变异、表观遗传学与非遗传学类的生化反应，导致研究者对于前列腺癌转移行为认知的不足。肿瘤转移过程起初被认为是一种符合达尔文进化论的行为，肿瘤细胞“物竞天择”地筛选出“最具适应性、活性最强”的癌细胞来进行转移。这一观点近来被推翻。本项目研究证实，癌肿的扩散与转移过程是由癌肿内一些“前体细胞”来介导，该过程在癌肿发生的早期阶段即已被启动。从癌肿中扩散出来的“前体细胞”或者是具有一定成熟度的转移癌细胞均具有癌干细胞的特性。同时，本项目对该亚群具有转移活性的癌干细胞进行了确切的鉴定，论证了原发性癌肿组织内的高转移活性干细胞亚群是引发前列腺癌扩散和转移的细胞源头。另一方面，本项目探讨了HOXB9在调控高转移活性癌干细胞的生物特性及前列腺癌肿转移过程中的重要作用。综上，本项目探究了可引发前列腺癌转移的细胞源头及重要调控分子，基于此来研发靶向制剂、提升常规抗肿瘤治疗的效果，是本项目提出的创新性理念。本项目研究的实施将显著推进人们对于前列腺癌转移这一生物学行为的认知和理解，从而为研发针对高转移活性前列腺癌干细胞亚群的靶向疗法提供数据支持与转化医学研究平台，以期为临床患者的抗癌治疗提供新颖的理念和手段。