Patrawala L, Calhoun T, Schneider-Broussard R, Li H, Bhatia B, Tang S, Reilly J G, Chandra D, Zhou J, Claypool K, Coghlan L, Tang D G
Department of Carcinogenesis, The University of Texas MD Anderson Cancer Center, Science Park-Research Division, Smithville, 78957, USA.
Oncogene. 2006 Mar 16;25(12):1696-708. doi: 10.1038/sj.onc.1209327.
CD44 is a multifunctional protein involved in cell adhesion and signaling. The role of CD44 in prostate cancer (PCa) development and progression is controversial with studies showing both tumor-promoting and tumor-inhibiting effects. Most of these studies have used bulk-cultured PCa cells or PCa tissues to carry out correlative or overexpression experiments. The key experiment using prospectively purified cells has not been carried out. Here we use FACS to obtain homogeneous CD44(+) and CD44(-) tumor cell populations from multiple PCa cell cultures as well as four xenograft tumors to compare their in vitro and in vivo tumor-associated properties. Our results reveal that the CD44(+) PCa cells are more proliferative, clonogenic, tumorigenic, and metastatic than the isogenic CD44(-) PCa cells. Subsequent molecular studies demonstrate that the CD44(+) PCa cells possess certain intrinsic properties of progenitor cells. First, BrdU pulse-chase experiments reveal that CD44(+) cells colocalize with a population of intermediate label-retaining cells. Second, CD44(+) PCa cells express higher mRNA levels of several 'stemness' genes including Oct-3/4, Bmi, beta-catenin, and SMO. Third, CD44(+) PCa cells can generate CD44(-) cells in vitro and in vivo. Fourth, CD44(+) PCa cells, which are AR(-), can differentiate into AR(+) tumor cells. Finally, a very small percentage of CD44(+) PCa cells appear to undergo asymmetric cell division in clonal analyses. Altogether, our results suggest that the CD44(+) PCa cell population is enriched in tumorigenic and metastatic progenitor cells.
CD44是一种参与细胞黏附和信号传导的多功能蛋白质。CD44在前列腺癌（PCa）发生和发展中的作用存在争议，一些研究显示其具有促肿瘤和抑肿瘤作用。这些研究大多使用批量培养的PCa细胞或PCa组织进行相关性或过表达实验。尚未进行使用前瞻性纯化细胞的关键实验。在此，我们使用荧光激活细胞分选术（FACS）从多种PCa细胞培养物以及四个异种移植肿瘤中获得均一的CD44(+)和CD44(-)肿瘤细胞群体，以比较它们的体外和体内肿瘤相关特性。我们的结果显示，与同基因的CD44(-) PCa细胞相比，CD44(+) PCa细胞具有更强的增殖、克隆形成、致瘤和转移能力。随后的分子研究表明，CD44(+) PCa细胞具有祖细胞的某些内在特性。首先，BrdU脉冲追踪实验显示CD44(+)细胞与一群中等程度保留标记的细胞共定位。其次，CD44(+) PCa细胞表达几种“干性”基因（包括Oct-3/4、Bmi、β-连环蛋白和SMO）的mRNA水平更高。第三，CD44(+) PCa细胞在体外和体内均可产生CD44(-)细胞。第四，AR(-)的CD44(+) PCa细胞可分化为AR(+)肿瘤细胞。最后，在克隆分析中，极小比例的CD44(+) PCa细胞似乎经历不对称细胞分裂。总之，我们的结果表明，CD44(+) PCa细胞群体富含致瘤和转移祖细胞。
