IQGAP1在人骨髓瘤细胞中过表达且与ERK相互作用

 目的：探讨含IQ模序的GTP酶活化蛋白1(IQ motif-containing GTPase-activating protein 1，IQGAP1)在骨髓瘤细胞中的过表达及其机制。方法：RT-PCR和Western blotting 检测RPMI8226和U266细胞IQGAP1表达；使用不同的寡核苷酸序列构建沉默人IQGAP1的shRNA质粒（clone 1、clone 2、clone 3和clone 4）、转染RPMI8226细胞，RT-PCR和Western blotting检测其IQGAP1表达；Western blotting检测RPMI8226-shIQGAP1组 (clone 1)、RPMI8226-shRNA阴性对照组和RPMI8226未转染组细胞p-ERK1/2、ERK1/2、Akt、p-AKT、STAT3和p-STAT3水平，免疫共沉淀确定IQGAP1和ERK的关系。结果：IQGAP1在RPMI8226和U266骨髓瘤细胞株中过表达，使用shRNA表达质粒沉默RPMI8226细胞IQGAP1 后，IQGAP1表达减少，在有或无血管内皮生长因子（VEGF）/白细胞介素6（IL-6）作用下检测RPMI8226-shIQGAP1组 (clone 1) 细胞增殖明显下降。进一步检测3组细胞p-ERK1/2、ERK1/2、AKT、p-AKT、STAT3和p-STAT3蛋白水平，与RPMI8226-shRNA阴性对照组和RPMI8226未转染组相比，RPMI8226-shIQGAP1组ERK1/2磷酸化水平下降70.2%，免疫共沉淀法明确在RPMI8226细胞中IQGAP1和ERK存在相互作用。结论：IQGAP1在骨髓瘤细胞中的过表达可能与MAPK途径的ERK相互作用有关。

IQGAP1 is overexpressed and interacts with ERK in human myeloma cells

AIM:To explore the role of IQ motif-containing GTPase-activating protein 1 (IQGAP1) in the cell proliferation of multiple myeloma and its mechanism. METHODS:RT-PCR and Western blotting were performed to detect the expression of IQGAP1 in human myeloma cell lines RPMI8226 and U266. shRNA-expressing plasmids were used to transfect into RPMI8226 cells to knock down the expression of IQGAP1. MTT assay was used to examine the proliferation of RPMI8226-shIQGAP1 (clone 1) cells, RPMI8226-shRNA negative control cells and un-transfected RPMI8226 cells with or without VEGF/IL-6 treatment. The protein levels of p-ERK1/2, ERK1/2, AKT, p-AKT, STAT3 and p-STAT3 in RPMI8226-shIQGAP1 (clone 1) cells, RPMI8226-shRNA negative control cells and un-transfected RPMI8226 cells were measured by Western blotting. The interaction between IQGAP1 and ERK was determined by the method of co-immunoprecipitation. RESULTS:IQGAP1 was overexpressed in human myeloma cell lines RPMI8226 and U266 as compared with normal lymphocytes. Transfection with shRNA targeting to IQGAP1 decreased the expression levels of IQGAP1 in RPMI8226 cells. The proliferation of RPMI8226 cells decreased when IQGAP1 was knocked down by shRNA with or without VEGF/IL-6 treatment. IQGAP1 affected the proliferation of RPMI8226 cells by regulation of MAP kinase (ERK1/2) pathway. The level of p-ERK1/2 in RPMI8226-shIQGAP1 (clone 1) cells decreased by 70.2% as compared with RPMI8226-shRNA negative control cells and un-transfected RPMI8226 cells. The interaction between IQGAP1 and ERK in RPMI8226 cells was observed. CONCLUSION: IQGAP1 plays an important role in the cell proliferation of multiple myeloma via MAP kinase (ERK) pathway.