CXCR4在肺癌转移中的作用及其机制研究

目的 探讨CXCR4在肺癌转移中的作用及其机制。方法 将CXCR4不同表达水平的肺癌细胞(95C、95C-pc、95C-X4、95D、95D-pC、95D-ASX4)接种于裸鼠皮下并分析其转移能力。分别通过趋化侵袭实验、明胶酶谱法、黏附实验、RT-PCR法检测CXCR4／SDF-1对肺癌细胞迁移、基质金属蛋白酶(MMP-2)活性、黏附能力、生长相关癌基因-α(GRO-α)表达的调控;通过流式细胞术和共聚焦显微镜观察肺癌细胞内纤维肌动蛋白的合成和聚合情况;Western印迹分析CXCR4／SDF-1对ERK1／2磷酸化的影响。结果 CXCR4不同表达水平的肺癌细胞在裸鼠体内具有不同的转移能力,95D-ASX4组有2／5的小鼠发生了转移,其肺转移结节的数目明显少于95D、95D-pC组(P=0．044)。CXCR4特异配体SDF-1α可以诱导肺癌细胞的迁移和细胞骨架蛋白纤维肌动蛋白的合成和聚合;SDF-1α促进肺癌细胞MMP-2活性、黏附能力和GRO-α表达的增加;CXCR4中和抗体可以在一定程度上抑制这些作用。SDF-1α可以诱导ERK1／2的磷酸化。结论 肺癌转移在一定程度上依赖于CXCR4／SDF-1的相互作用,他们通过调控肺癌细胞的运动性、MMP活性、黏附能力及GRO-α的表达参与肺癌的转移。

The role of CXCR4 in lung cancer metastasis and its possible mechanism

Objective To investigate the role of CXCR4 in the metastasis of human lung cancer and its possible mechanism. Methods Lung cancer cells of the lines 95C and 95D with high or low metastatic potential were transfeted with CXCR4 antisense plasmid pcDNA-ASX4, whole length eukaryotic expression plasmid pcDNA-CXCR4 (95D-ASX4 and 95C-X4 cell lines), and corresponding plasmid pcDNA3 (95C-pC and 95D-pC cell lines). 95C, 95C-pC, 95C-X4, 95D, and 95D-pC cells were injected subcutaneously into Balb/c nu/nu mice, 4~5 mice in a group. The mice were observed twice a week. Ten weeks later the mice were killed and the tumor in situ and the lungs were taken out to undergo histological examination. The effect of CXCR4 expression on the cell migration, MMP-2 activity, adhesion and GRO-a expression of lung cancer cells were detected by chemotaxis and chemoinvasion assay, zymography, adhesion assay and RT-PCR respectively. The polymerization of F-actin was measured by FACS and confocal microcopy. Western blotting was used to detect the phospharylation of ERK1/2 in 85D cells Results Metastasis was not found in the mice injected with 95C and 95C-pC cells, and was seen in 2/5 of the mice injected with 95C-X4 cells, 3/4 of the mice injected with 95D and 95D-pC cells, 2/5 of the mice injected with 95D-ASX4 cells, however, the number of metastatic nodes in the lungs of 95D-ASX4 group was significantly less than those in the 95D and 95D-pC groups (P=0.044). SDF-1a, a CXCR4 specific ligand, induced the migratory response and F-actin polymerization in the lung cancer cells; SDF-1a promoted the MMP-2 activity, the adhesion to vascular endothelial cells and GRO-a expression; and neutralizing CXCR4 antibody inhibited these effects to some degree. Moreover, SDF-1a induced the phosphorylation of ERK1/2 in human lung cancer cells. Conclusion~Metastasis of human lung cancer depends on, to some degree, the interaction of CXCR4 and SDF-1 that are involved in this process by regulating the active locomotion, MMP-2 activity, adhesion ability or GRO-a expression.