目的：在原位移植瘤模型上验证CD44+胃癌细胞的肿瘤干细胞特性。方法：选取MKN-45胃癌细胞株，通过流式细胞仪分选为CD44+和CD44-两组，以未分选的MKN-45胃癌细胞为对照。体外部分，通过MTT法和克隆形成实验验证CD44+胃癌细胞体外增殖能力，通过Transwell实验验证其侵袭力。体内部分，将上述细胞通过原位移植法接种至裸鼠，同等条件下饲养8周后处死裸鼠，检验其成瘤率；分离肝脏，检测肝转移瘤数目；H-E染色观察胃肿瘤和肝转移瘤形态；通过免疫荧光法检测两处肿瘤CD44+细胞数量。结果：CD44+胃癌细胞相比CD44-胃癌细胞具有明显增强的细胞增殖力（P<0.01）和侵袭力（P<001），更容易成瘤且更容易发生转移（P<0.05），但和MKN-45未分选组相比差异无统计学意义（P>0.05）。不论是在原发肿瘤还是转移瘤中，CD44+胃癌细胞均能产生CD44-细胞，但后者不能产生CD44+细胞。结论： CD44+MKN-45胃癌细胞相比CD44-胃癌细胞具备更强的增殖力和侵袭力、更容易成瘤和发生转移，符合肿瘤干细胞部分特征，值得进一步研究。

Objective:To confirm cancer stem cell characteristics of CD44+ gastric cancer cell in orthotopic carcinoma xenograft model. Methods: MKN-45 gastric cancer line cells were separated into two cell groups, CD44+ and CD44-, with flow cytometry assay, as well as non-separated MKN-45 gastric cancer cell as control. Proliferation in vitro of CD44+ gastric cancer cell was detected by MTT and colony formation assays and its invasion ability in vitro tested by Transwell assay. The above gastric cancer cells were injected into nude mice by orthotopic tansplantation method. The transplanted nude mice were killed and detected for their rates of tumor formation after breeding for 8 weeks under the same conditions. Their livers were taken out and counted the number of hepatic metastasis. Shapes of gastric tumor and metastatic tumor in liver were observed with H-E staining. Numbers of the CD44+ cell in both the tumors were counted by immunofluorescence assay. Results: Compared with CD44- gastric cancer cell, proliferation and invasion abilities of CD44+ gastric cancer cell obviously enhanced ( all P<0.01), formation of tumor and metastasis more frequently occurred (P<005), but compared with non-separated MKN-45 gastric cancer cell there not were any statistic differences (P>0.05). Whether in primary tumor or in metastatic one, CD44+ gastric cancer cells could all produce CD44- gastric cancer cells, but the latter could not produce the CD44+ cells. Conclusion: Compared with CD44- gastric cancer cells, CD44+ MKN-45 gastric cancer cells could have more stronger proliferation and invasion abilities, and be more likely to become tumor and metastasis, which meet partial characteristics of cancer stem cell. It might be valuable to further investige.

上海市科委实验动物项目资助（No. 13140901803），上海市科委中医引导科技项目资助（No. 13401907500），国家自然科学基金支持项目（No. 81503391）