CMTM6基因促进结肠癌转移及其机制研究

Tumor metastasis is the main cause of poor prognosis in colon cancer patients. We found the expression of CMTM6 in tumors is closely related to tumor metastasis. The prognosis of patients with high expression of CMTM6 was poor; the expression of CMTM6 in tumor metastasis group was significantly higher than that in non-metastasis group; the expression of CMTM6 could predict the occurrence of postoperative metastasis.We found CMTM6 can promote the migration of colon cancer cells in vitro by wound healing and transwell test. Furthermore, we found that the expression of CMTM6 is positively correlated with CD14 and regulate the expression of CD14 protein at the post-transcriptional level. Studies have shown that LPS can promote cancer metastasis by regulating the TLR4 pathway, and CD14 is a key protein in upstream of the TLR4 pathway. After knocking down CMTM6, the expression of key protein in TRL4 downstream signaling pathway is significantly changed. Therefore, we supposed that CMTM6 is likely to promote the metastasis of colon cancer by regulating the expression of CD14 protein and participating in the LPS-TLR4 signaling pathway. CMTM6 is expected to be an effective marker for finding early and potential metastases.

肿瘤转移是导致肠癌患者预后不良的主要原因，课题组前期发现肿瘤内CMTM6的表达量与肠癌转移密切相关。CMTM6高表达患者预后较差；术后肿瘤转移组患者CMTM6表达量显著高于未转移组；CMTM6的表达量能够很好的预测术后转移的发生。我们通过细胞划痕、Transwell等体外试验证实了CMTM6能够促进肠癌细胞的迁移。此外，我们发现CMTM6的表达与CD14的表达正相关，且在转录后水平调控CD14蛋白的表达。已有研究提示LPS能够通过调控TLR4通路促进肠癌转移，而CD14恰好是TLR4通路上游的重要蛋白，我们敲降CMTM6后，TRL4下游信号通路关键蛋白表达明显改变。因此，我们提出假说“肠癌细胞表达的CMTM6很可能通过调控CD14蛋白的表达，参与LPS-TLR4信号通路来促进肠癌的转移“。CMTM6有望成为发现早期转移、寻找潜在转移灶的有效标志物。

本研究主要通过体内、体外实验，证实了cmtm6基因促进肠癌转移的潜在机制。cmtm6一方面能够通过促进肠癌细胞的迁移作用，促进肿瘤转移的发生；另一方面，通过研究肿瘤组织内cmtm6与CD14的表达相关性，我们挖掘了cmtm6对肿瘤微环境的免疫调控作用。建立在团队现有研究基础之上，我们认为cmtm6可以通过调控PD-L1的稳定性，抑制CD14+DC细胞分泌趋化因子CXCL9/CXCL10，从而抑制肿瘤内免疫细胞CD45RO+T细胞的组织浸润，促进转移的发生。借助小鼠原位癌、肝转移瘤、肺转移瘤模型，我们证实了以上PD-L1对CD45RO+T细胞的浸润抑制作用。后经过反复实验，我们证实了小鼠mc38细胞中cmtm6的表达情况，解决了构建非免疫缺陷小鼠模型的问题，构建了CMTM6基因敲除工具细胞，期望进一步验证cmtm6对免疫浸润的潜在影响。.通过对临床标本的检测，我们发现肠癌患者肿瘤表达的cmtm6能够很好的预测术后肿瘤转移的发生，有望成为预测患者生存的重要生物标志物。借助单细胞测序技术，我们证实了CD45RO+T细胞亚群在不同病变程度的组织中的浸润差异，这有利于通过检测肠镜活检组织中的免疫浸润情况来判断病变的性质，提高早期肠癌的诊断效率。

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