c-Kit+细胞对CD44v6+结肠癌干细胞的支持及消痰散结方的干预作用

The cancer stem cell niche played an important role in the maintenance of the cancer stem cells (CSCs), it also contributed to the cancer cell invasion and metastasis and was regarded as a potential anti-cancer target. Our previous studies indicated that c-Kit+ cells are likely to be one of the most important cells which fabricate the niche for colorectal cancer stem cells (CCSCs), it would maintain the survival of CCSCs via manipulating the Notch signaling pathway, but it was still largely unknown if these cells changed from the “normal cells→cancer cells” on the process of colorectal tumor malignant transformation. Traditional Chinese medicine established an important role in the treatment of cancers, in previous study, we observed that Xiaotan Sanjie decoction could inhibit cell proliferation of CD44+ gastric CSCs by regulating Notch, it can also down-regulate CD44v6, which was demonstrated to be a key marker for CCSCs recently. In this study, we aimed to isolate the CD44v6+ CCSCs, c-Kit+ cells by FACS, observe the biological characteristics’ variation of c-Kit+ cells with CD44v6+ CCSCs in different condition and the activation of Notch. We are also trying to explore the role of Xiaotan Sanjie decoction to colorectal cancer stem cell niche and its potential mechanisms; at last, we would estimate the predictive value of the existence of niche and the activation of Notch in patients of colorectal adenoma and carcinoma. The results of our study would shed light to the therapy of colorectal cancer by traditional Chinese medicine in future.

肿瘤干细胞巢对维持肿瘤干细胞生存、促进其侵袭和转移等均具有重要意义，是潜在的抗肿瘤靶点。课题组前期研究提示，c-Kit+细胞有可能是结肠肿瘤干细胞巢构成组份，其可通过Notch信号通路维持结肠癌干细胞生存，但其在结肠肿瘤恶性演变过程中是否经历了“正常细胞→癌细胞”的转变尚十分不清楚。中医药在抗肿瘤中具有重要作用，我们前期研究发现消痰散结方能通过调控Notch通路抑制CD44+胃癌干细胞增殖，下调CD44v6，后者近期更是被证明为结肠癌干细胞的重要标记。本课题拟通过流氏细胞术分选CD44v6+结肠癌干细胞、c-Kit+细胞，观察不同条件下c-Kit+细胞对结肠癌干细胞生物学特性的影响及Notch通路的作用；探索消痰散方对结肠癌干细胞巢的作用及其潜在机制；分析人结肠腺瘤和腺癌标本中干细胞巢的存在及Notch激活状态对患者预后判断的价值，本研究结果可为未来中医药治疗结肠癌提供一定依据。

结肠肿瘤干细胞及其所在的微环境（干细胞巢）是近年来肿瘤研究的热点，以CD44为代表的分子标记被广泛用于筛选胃肠道肿瘤干细胞，但由于肿瘤干细胞生物学特性的复杂，对使用CD44标记结肠肿瘤干细胞是否准确存在一定争议。本研究在既往基础上，选择以CD44家族异构体CD44v6作为潜在干细胞标记，通过体内外实验研究CD44v6+结肠癌细胞的干性，并试图分析以c-Kit+细胞为标记的干细胞巢成分对该细胞的作用；论证Notch信号通路对CD44v6+细胞生物学特性的影响；分析基于中医肿瘤“痰”学说的复方制剂-消痰散结方的作用及潜在机制。研究结果表明CD44v6+结肠癌细胞具备肿瘤干细胞特性，在体外研究中，其在细胞增殖、成球、侵袭等方面均优于CD44v6-细胞，而在体内研究中，其成瘤能力显著强于CD44v6-细胞；c-Kit+细胞对CD44v6+结肠癌干细胞是否存在支持作用尚需进一步研究。CD44v6+结肠癌干细胞的部分生物学特性可能和其高表达Notch-1信号通路有关。消痰散结方对CD44v6+细胞移植瘤具有一定抑制作用，这可能是其抗肿瘤潜在机制之一。CD44、CD44v3和CD44v6在结直肠癌患者中存在表达，这些分子标记物对结直肠癌患者的预后存在重要判断价值。研究结果表明CD44v6可能是更合适的结肠癌干细胞标记，Notch信号通路参与调控其部分生物学功能，消痰散结方对结肠癌具有一定治疗价值，其潜在机制可能和其作用于CD44v6+细胞并调控Notch信号通路有关。