肿瘤间充质干细胞通过CCL22影响非小细胞肺癌化疗敏感性的机制研究

The chemotherapy response rate in non-small cell lung caner (NSCLC) patients is relatively low, however, the involved mechanisms remain largely unknown. Our preliminary study demonstrated that mesenchymal stem cell (MSCs) reduced chemosensitivity to cisplatin in mouse bearing lung cancer xenografts and CCL22 expression in MSCs was remarkably up-regulated by cisplatin treatment; but the regulating mechanism of CCL22 and its contribution to lower chemosensitivity to cisplatin are obscure and need to be further elucidated. CCL22 is a key chemokine for recruiting Treg to tumor microenvironment; the damage signals induced by chemotherapy could activate Toll-like receptors (TLRs), which subsequently promote the release of chemokines and cytokines. Thus we speculate the damage signals induced by cisplatin treatment would activate TLRs in MSCs and increase the expression of CCL22, which results in accumulation of Treg into tumor microenvironment and reduced sensitivity to cisplatin. In the present project, we intend to systematically investigate the role of MSCs in chemosensitivity to cisplatin and explore the possible mechanisms involved in this process, especially via recruitment of Treg by CCL22 through TLRs activation. Besides, we will analyze the correlation between Treg infiltration, plasma CCL22 level and cisplatin efficacy in advanced NSCLC patients. Our study may help to further reveal the role of tumor microenvironment, especially MSCs, and underlying mechanisms in modulating chemosensitivity to cisplatin, which will provide clues for the prediction and improvement of chemosensitivity.

晚期非小细胞肺癌化疗的有效率较低，影响化疗药物敏感性的因素和机制尚不明确。前期研究发现给予肺癌荷瘤小鼠注射间充质干细胞（MSCs）可导致肿瘤对顺铂敏感性下降，进一步分析发现顺铂可显著上调CCL22在MSCs的表达，但其机制及与化疗敏感性的关系尚不清楚。CCL22是趋化Treg至肿瘤局部的关键因子，而化疗引发的损伤信号可激活Toll样受体（TLRs），后者参与多种趋化/细胞因子的调控；因此我们推测顺铂化疗引发损伤信号的释放，激活MSCs表面的TLRs、促进其CCL22表达，继而介导Treg向肿瘤局部募集，从而降低顺铂敏感性。本课题拟系统研究MSCs对顺铂敏感性的影响，探讨TLRs-CCL22-Treg在其中的作用和参与机制，并分析NSCLC患者Treg浸润、CCL22表达与化疗疗效的相关性；研究将有助于明确肿瘤微环境特别是MSCs在顺铂化疗敏感性中的作用，为化疗敏感性预测和提高提供理论依据。

以铂类药物为基础的联合化疗是晚期非小细胞肺癌的主要治疗手段之一，但其有效率较低，影响铂类药物敏感性的因素和机制尚不明确。本课题主要研究了肿瘤间充质干细胞（mesenchymal stem cells, MSCs）对非小细胞肺癌（non-small cell lung cancer，NSCLC）顺铂化疗敏感性的影响，并通过体内外试验及晚期NSCLC患者标本检测分析、验证其中的参与机制。体外研究部分，首先检测了不同浓度、作用时间的顺铂对MSCs细胞活力的影响，确定试验条件。顺铂体外处理MSCs后，PCR Array、ELISA等检测MSCs趋化因子、细胞因子以及其他免疫相关分子的表达改变。结果发现，除CCL22表达上调外，IL-6、CCL2、Glycodelin的表达也发生了显著上调。进一步对IL-6等在顺铂处理后MSCs的表达改变的调控通路进行了研究和验证。体内研究部分，荷瘤小鼠模型研究发现，MSCs可导致肺癌对顺铂的抑瘤作用下调，这些结果证实MSCs在体内也参与了顺铂敏感性的调控，参与的具体机制可能包括IL-6、CCL22等因子和T细胞等免疫细胞。临床研究部分，我们检测了晚期NSCLC患者病理组织中间质细胞、T细胞浸润的表达，并分析了其与铂类药物化疗疗效、生存期之间的关系。结果表明，间质细胞浸润高患者对铂类为基础的化疗应答率低，而CD8+/CD4+比例高者对化疗敏感、具有更长的无进展生存期。这从临床角度对实验室研究的发现进行了间接验证。本课题研究的结果将有助于明确肿瘤微环境特别是MSCs在顺铂化疗敏感性中的作用，为化疗敏感性预测和提高提供理论依据。