CXC趋化因子受体4通过S期激酶相关蛋白2调控乳腺癌细胞周期的机制

目的：探讨CXC趋化因子受体4（CXCR4）通过PI3K/Akt和ERK信号通路调控S期激酶相关蛋白2（Skp2）的表达，进而影响乳腺癌细胞周期的机制。方法：利用干扰及过表达技术下调或上调CXCR4的表达后，通过实时定量PCR和蛋白质印迹法检测CXCR4与Skp2调控的关联性；蛋白质印迹法检测CXCR4干扰及过表达后对信号蛋白及Skp2下游相关基因表达的影响；通过碘化丙啶（PI）染色法检测CXCR4、PI3K/Akt通路抑制剂LY294002及ERK通路抑制剂U0126对乳腺癌细胞周期的影响。结果：干扰CXCR4后，Skp2表达下调；过表达CXCR4后，Skp2表达上调。CXCR4可通过对信号蛋白的调控影响Skp2及Skp2下游相关基因的表达。干扰CXCR4后，G0/G1期细胞比例增加，S期细胞比例相应减少，CXCR4与LY294002及U0126联合作用对细胞周期的阻断更加明显。结论：CXCR4能够通过对信号蛋白PI3K/Akt及ERK的调控，影响Skp2及Skp2下游相关基因的表达，阻断CXCR4/Akt/Skp2或CXCR4/ERK/Skp2信号通路后可有效诱导细胞周期阻滞，从而抑制乳腺癌细胞的增殖。
Abstract: Objective:To investigate the effect of CXC chemokine receptor 4 (CXCR4) on cell cycle of breast cancer and its molecular mechanisms. Methods:The expression of CXCR4 and S phase kinase associated protein 2 (Skp2) was detected by real-time fluorescence quantitative PCR (fqRT-PCR) and Western blot in breast cancer cells. The expression of signal proteins and the downstream genes of Skp2 was detected by Western blot. The effect of CXCR4, PI3K/Akt pathway inhibitor LY294002 and ERK pathway inhibitor U0126 on cell cycle of breast cancer was detected by propidium iodide staining. Results:Skp2 was significantly down-regulated in CXCR4-downregulated cells and up-regulated in CXCR4-upregulated cells. CXCR4 also regulated the expression of Skp2 and other downstream genes by signaling protein. The proportion of cells in G0/G1 phase increased and that in S phase declined in CXCR4-downregulated cell, and the effect was more significant when combined with the use of LY294002 or U0126. Conclusion:CXCR4 can affect cell cycle and inhibit the proliferation of breast cancer cells by regulating Skp2 gene expression through PI3K/Akt and ERK signaling pathway. Key words: Breast neoplasms/physiopathology Receptors, CXCR4/biosynthesis Receptors, CXCR4/genetics S-phase kinase-associated proteins/metabolism Cell line, tumor/metabolism Cell proliferation Cell cycle