PRL-3上调CCL-26诱导TAM浸润促进结肠癌肝转移的作用机制研究

Phosphatase of regenerating liver-3(PRL-3) is a key phosphotase which induces epithelial-mesenchymal transitions (EMT) of cacer cells and the EMT is the major mechanism by which PRL-3 promotes the liver metastasis of colon cancer. Our research firstly confirm that PRL-3 can induce the infiltration of tumor-associated macrophages (TAM) to secrete cytokines IL-6 and IL-8 leading to the EMT of colon cancer cells in tumor microenvironment. However, the mechanism is still unknown. Our preliminary study has revealed PRL-3 induces the CCL-26 expression of colon cells and the surface of TAM can also express CCL-26 sepecific receptor CCR3. Thus, we firstly propose a new hypothesis that PRL-3 induces the colon cancer cells liver metastasis through the infiltration of TAM in a CCL-26-dependent manner. In this research, we will futher explore the mechanism by which PRL-3 induces the CCL-26 expression through CHIP-PCR and Dual-Luciferase Reporter Assay System methods. Cell co-cultured method and animal experiments are also used to find the key signal pathways which are response for the infiltration of TAM and secretion of TAM-derived IL-6 and IL-8. The study is expected to clarify the novel mechanism by which the PRL-3 promote the colon cancer liver metastasis and find new targets for the treatment of colon cancer liver metastasis.

PRL-3是诱导结肠癌上皮间质化（EMT）的磷酸酶，EMT则是结肠癌发生肝转移的重要分子作用机制。前期研究证实PRL-3可趋化肿瘤相关性巨噬细胞（TAM）浸润从而使其分泌IL-6和IL-8进而诱导结肠癌EMT的发生，但具体作用机制尚不清楚。预实验证实PRL-3可上调结肠癌细胞CCL-26的表达，TAM细胞可表达CCL-26受体CCR3，提示CCL-26可能参与了PRL-3诱导TAM的浸润过程，由此我们提出假说:PRL-3上调结肠癌细胞CCL-26的表达从而趋化TAM浸润进而诱导结肠癌发生肝转移。本研究拟通过CHIP-PCR、构建荧光素酶载体等技术进一步探讨PRL-3上调CCL-26表达的分子机制，通过细胞共培养、动物实验等探讨CCL-26趋化以及诱导TAM分泌IL-6和IL-8促进结肠癌肝转移的分子信号通路。本研究旨在完善PRL-3促进结肠癌肝转移的作用机制，为结肠癌肝转移治疗提供新靶点。

结直肠癌是我国常见的消化道恶性肿瘤，目前结直肠癌患者的死亡率在恶性肿瘤中排第 5 位，多数病人发生肝转移而死亡。 一期手术切除的患者 5 年生存率有 90%，而结直肠癌肝转移患者 5 年生存率仅有 12%，因此阐明结直肠癌肝转移的分子机制显得尤为重要。PRL-3 蛋白属于非典型性酪氨酸磷酸酶，在结肠癌组织中高表达，在良性结直肠肿瘤以及正常粘膜中低表达，提示其与肿瘤的转移和侵袭相关。在本研究中我们主要研究了PRL-3能否上调CCL-26诱导TAMs浸润，进而促进结直肠癌侵袭和转移。我们研究结果表明：1）PRL-3促进结肠癌细胞LoVo分泌趋化因子CCL-26。2）CCL-26通过受体CCR3结合诱导肿瘤相关性巨噬细胞浸润；3）在模拟肿瘤微环境下，TAMs促进高表达PRL-3结肠癌细胞的侵袭性。同时CCL-26通过CCR3受体动员细胞内钙离子激活TAMs的KCNN4和GSK-3β表达，进而分泌IL-6和IL-8促进结肠癌的侵袭。4）在病理标本中发现CCL-26、CCR3受体和TAMs随着TNM分期升高，表达逐渐升高。PRL-3、CCL-26和TAMs表达影响结肠癌患者预后。其科学意义在于探讨了PRL-3对促进结肠癌侵袭和转移的机制，为肿瘤的治疗提供理论支持；发现PRL-3可以上调趋化因子CCL-26的表达，从而诱导TAMs浸润，为肿瘤微环境的研究提供进一步理论支持；在结肠癌患者的病例标本中分析了PRL-3，CCL-26和TAMs在结直肠癌组织中与肿瘤分期之间的关系，发现CCL-26的表达可作为判断结肠癌患者预后的独立危险因素。