趋化因子受体CXCR4及其配体CXCL12在肝癌侵袭 转移中的作用及机制

目的 探讨趋化因子受体 CXCR4 及其配体 CXCL12（CXCL12/CXCR4）在原发性肝癌侵袭转移中的作用 及机制。方法 分别采用 Western blot、免疫组化和 Real-time PCR 等方法检测 60 例肝癌及对应癌旁组织标本中 CXCL12/CXCR4 蛋白及 mRNA 表达水平。常规培养 4 种肝癌细胞（Huh7、MHCC97h、HepG2、Hep3B）和正常肝细胞 （7702），Real-time PCR 检测上述细胞中 CXCL12、CXCR4 mRNA 的表达，筛选合适的实验细胞。将 CXCR4 干扰质 粒（sh-CXCR4）和对应空载体（sh-control）分别转染至 MHCC97h 构建稳转细胞系。Transwell 侵袭实验、细胞划痕实 验、MTT 实验分别检测 2 组细胞的侵袭、迁移和增殖能力。取稳定表达的 sh-control 和 sh-CXCR4 MHCC97h 细胞， 接种至 6 只裸鼠皮下，观察瘤体生长情况。Western blot 检测 sh-control 和 sh-CXCR4 MHCC97h 细胞及对应裸鼠移 植瘤中血管内皮生长因子-C（VEGF-C）的表达，同时对转染 CXCR 过表达质粒的 MHCC97h 中 VEGF-C 的表达水平 进行检测。结果 （1）Western blot、免疫组化和 Real-time PCR 的结果均证实肝癌组织中 CXCL12/CXCR4 蛋白及 mRNA 表达水平均高于癌旁组织。（2）Huh7、MHCC97h、HepG2、Hep3B 细胞中 CXCL12/CXCR4 mRNA 表达水平均高 于 7702 细胞，选取 MHCC97h 为实验细胞。转染 sh-CXCR4 的 MHCC97h 细胞的侵袭、迁移和增殖能力均明显低于 sh-control 组，同时接种含 sh-CXCR4 的 MHCC97h 细胞的裸鼠移植瘤的生长速度也明显小于 sh-control 组。（3）体外 和体内实验均证实 sh-CXCR4 组的 VEGF-C 表达水平均低于 sh-control 组，而过表达 CXCR4 后，VEGF-C 的蛋白表 达明显上调。结论 CXCL12/CXCR4 在原发性癌组织和肝癌细胞中呈现高表达，CXCL12/CXCR4 可能通过调控 VEGF-C 蛋白表达从而抑制肝癌细胞的增殖、侵袭和转移。

The mechanism and biological function of chemokine receptor CXCR4 and its ligand CXCL12 in hepatocellular carcinoma

Objective To investigate the mechanism and function of chemokine receptor CXCR4 and its ligand CXCL12 (CXCL12 / CXCR4) in primary hepatocellular carcinoma (PHC). Methods Western blot assay, immunohistochemistry and Real-time PCR were used to detect the protein and mRNA expressions of CXCL12/CXCR4 in 60 PHC and corresponding paracancerous tissue samples. Four kinds of hepatoma cells (Huh7, MHCC97h, HepG2 and Hep3B) and normal hepatocytes (7702) were routinely cultured, and then real-time PCR was performed to detect the mRNA expressions of CXCL12 / CXCR4 in these cells to screen suitable experimental cells. CXCR4 interference plasmid (shCXCR4) and corresponding empty vector (sh-control) were transfected into MHCC97h to construct stable transfected cell lines. The ability of invasion, migration, and proliferation of the 2 groups of cells were detected by Tanswell invasion experiment, cell scratch test and MTT test. The stably expressed sh-control and sh-CXCR4 MHCC97h cells were taken into the subcutaneous of six nude mice, and the growth of the tumor was observed. Western blot assay was used to detect the expressions of vascular endothelial growth factor-C (VEGF-C) in sh-control and sh-CXCR4 MHCC97h cell lines and corresponding xenografts in nude mice, as the same in MHCC97h, which was transfected with CXCR overexpressed plasmid. Results (1) The results of Western blot assay, immunohistochemistry and Real-time PCR showed that the expressions of CXCL12/CXCR4 protein and mRNA were significantly higher in liver cancer tissues than those of paracancerous tissues. (2) The expression levels of CXCL12/CXCR4 mRNA were higher in Huh7, MHCC97h, HepG2 and Hep3B cells than those of 7702 cells. MHCC97h was selected as the experimental cells. The ability of invasion, migration and proliferation of MHCC97h cells transfected with sh-CXCR4 were significantly lower than those of sh-control group. Meanwhile, the growth rate of nude mice transplanted with sh-CXCR4 MHCC97h cells was also significantly lower than that of sh-control group. (3) Both in vitro and in vivo experiments showed that the expression of VEGF-C was lower in sh-CXCR4 group than that in shcontrol group, and the expression of VEGF-C was obviously up-regulated after overexpression of CXCR4. Conclusion High expressions of CXCL12/CXCR4 are found in primary cancer tissues and hepatoma cells. CXCL12/CXCR4 may inhibit the proliferation and invasion of hepatoma cells by regulating the expression of VEGF-C protein.