间质细胞诱导结直肠癌腺上皮细胞去分化在化疗耐药中的作用及机制研究

Recent studies have shown that cancer stem cells(CSCs) mediate drug resistance in human colorectal cancers (CRCs), and their proportion substantially increases in clinically chemotherapy-refractory tumor specimens, however, the cell-of-origin of CSCs in the recurrent CRCs remains largely unkown.Tumor-associated myofibroblasts(TAF) were shown to induce committed differentiated epithelial cells into CSCs in CRC, and also involve in drug resistance. Our preliminary data has demonstrated that,upon administration of oxaliplatin, a commonly used chemotherapeutic agent for advanced CRC, committed differentiated epithelial cells with co-injection of TAF in vivo aquire tumorigenic capability,and form more spheres in conditioned medium derived from TAF in vitro. Based on our preliminary data, we hypothesize that TAF induce drug resistance via de-differentiating of committed differentiated epithelial cells into CSCs in CRCs. We proposed four main aims: 1)To find out which cytokine(s) derived from TAF induce differentiated epithelial cells to be chemotherapeutic resistance in CRCs; 2)To explore whether differentiated cells de-differentiate into CSCs so as to be drug resistant; 3) To demonstrate whether it is the general principle, which is also applied to other chemotherapeutic agents for CRC, such as 5-FU,irinotecan; 4) To explore whether wnt signaling pathway involves in regulating the de-differentiation of differentiated cells to be drug resistant via paracrine signal in CRC. If the proposed aims are well accomplished, the findings will provide great benefit for the patients suffering cancer, especially CRC.

研究表明结直肠癌干细胞与化疗耐药密切相关，化疗药物治疗后的复发临床肿瘤标本中肿瘤干细胞显著增加，但其细胞来源不太清楚。有研究发现，肿瘤相关成肌纤维细胞（TAF）能诱导结直肠癌分化细胞去分化为癌干细胞，而TAF已被证实在化疗耐药中起重要作用。我们的研究表明，在奥沙利铂的处理下，TAF共接种可诱导结直肠癌分化细胞（ALDH-CD133-）成瘤，而奥沙利铂处理TAF后获得的条件培养基可增强癌分化细胞的细胞球体形成能力。本课题将在我们的前期工作基础上，探讨条件培养基能否诱导癌分化细胞抵抗奥沙利铂而成瘤，寻找其中关键的细胞因子，并分析该过程中癌分化细胞是否去分化为癌干细胞；并探讨该现象是否同样存在于其他常用的化疗药物；此外，探讨如何调控WNT信号通路实现癌分化细胞去分化，揭示TAF通过旁分泌诱导结直肠癌分化细胞去分化在化疗抵抗中的作用，并初步阐明其分子机制，为治疗结直肠癌提供新思路。

研究表明结直肠癌干细胞与化疗耐药密切相关，化疗药物治疗后的复发临床肿瘤标本中肿瘤干细胞显著增加，但其细胞来源不太清楚。有研究发现，肿瘤相关成肌纤维细胞（TAF或CAF）能诱导结直肠癌分化细胞去分化为癌干细胞，而CAF已被证实在化疗耐药中起重要作用。我们在该项国家自然科学基金（81272660）的资助下探讨在化疗过程中CAF能否诱导结直肠癌分化细胞去分化为癌干细胞以及分子机制。我们研究发现：（1）化疗药物处理时，成纤维细胞（18Co和CAF）旁分泌促进结直肠癌细胞（细胞系和移植瘤细胞）的细胞成球能力和成瘤能力；（2）化疗药物处理时，成纤维细胞（18Co和CAF）旁分泌促进结直肠癌分化细胞（细胞系和移植瘤CD133-细胞）的细胞成球能力和成瘤能力；（3）成纤维细胞（18Co和CAF）旁分泌胞外体（exosome）促进结直肠癌分化细胞的细胞成球能力和成瘤能力；（4）胞外体wnt蛋白介导癌分化细胞去分化从而增强其细胞成球能力和成瘤能力。我们的研究表明在治疗结直肠癌时，除了靶向癌干细胞，还需靶向癌分化细胞和CAF，而胞外体wnt蛋白是潜在的靶点。