目的:观察T淋巴瘤侵袭转移诱导因子1(Tiam 1)对乳腺癌细胞增殖和迁移的影响并探讨其作用机制。方法:采用反转录-聚合酶链反应(RT-PCR)检测MCF-10A、MCF-7、BS524和MDA-MB-453细胞中Tiam 1的mRNA表达水平；构建对照短发卡RNA(shRNA)和Tiam 1 shRNA慢病毒稳定细胞系(对照组和实验组)，采用细胞计数试剂盒(CCK-8)法检测对照组和实验组细胞的增殖活力；采用Transwell检测对照组和实验组细胞的迁移能力；采用蛋白质印迹法(Western blot)检测细胞中血管内皮生长因子(VEGF)、E-钙黏蛋白(E-cadherin)和波形蛋白(Vimentin)的表达，组间比较采用n t检验。n 结果:与MCF-10A细胞(0.42±0.03)比较，MCF-7(1.71±0.13)、BS524(1.53±0.12)、MDA-MB-453(1.55±0.14)细胞中Tiam 1的mRNA相对表达水平增加，差异有统计学意义(n t＝6.953、5.811、6.105，n P<0.05)。与对照组细胞(1.80±0.15)比较，实验组细胞(0.61±0.04)的增殖活力下降，差异有统计学意义(n t＝4.829，n P<0.05)。与对照组细胞[(77.20±6.08)个]比较，实验组细胞[(31.15±2.82)个]的迁移能力降低，差异有统计学意义(n t＝4.036，n P<0.05)。对照组和实验组细胞中VEGF蛋白的相对表达水平分别为2.01±0.17和0.47±0.04；E-cadherin蛋白的相对表达水平分别为0.37±0.03和1.14±0.09；Vimentin蛋白的相对表达水平分别为1.49±0.12和0.51±0.04。与对照组细胞比较，实验组细胞中VEGF和Vimentin的蛋白表达下降，E-cadherin的表达增加(n t＝8.254、5.962、5.510，n P<0.05)。n 结论:Tiam 1在乳腺癌细胞中呈高表达，下调Tiam 1的表达可抑制乳腺癌细胞的增殖和迁移。“,”Objective:To observe effect of T lymphoma invasion and metastasis inducing factor 1 (Tiam 1) on breast cancer cell proliferation and migration and its molecular mechanism.Methods:Reverse transcriptase-polymerase chain reaction (RT-PCR) was used to detect the expression of Tiam 1 in MCF-10A, MCF-7, BS524 and MDA-MB-453 cells. Control short hairpin RNA (shRNA) and Tiam 1 shRNA lentivirus stable cell lines were constructed (control group and experience group). Cell counting kit-8 (CCK-8) was used to detect the proliferation activity in control group and experience group. Transwell was used to detect the migration ability in control group and experience group. The expression of vascular endothelial growth factor (VEGF), E-cadherin and Vimentin was detected by Western blotting.Results:Compared with MCF-10A cells (0.42±0.03), the relative mRNA expression of Tiam 1 in MCF-7 (1.71±0.13), BS524 (1.53±0.12) and MDA-MB-453 cells (1.55±0.14) significantly increased (n t=6.953, 5.811, 6.105, n P<0.05). Compared with control group (1.80±0.15), the proliferation activity in experience group (0.61±0.04) significantly decreased (n t=4.829, n P<0.05). Compared with control group (77.20±6.08), the migration ability in experience group (31.15±2.82) was significantly reduced (n t=4.036, n P<0.05). The relative expression of VEGF protein in control group and experience group were 2.01±0.17 and 0.47±0.04, respectively. The E-cadherin were 0.37±0.03 and 1.14±0.09, respectively. And the expression of Vimentin were 1.49±0.12 and 0.51±0.04, respectively. Compared with control group, the protein expression of Tiam 1 and Vimentin decreased, and the expression of E-cadherin increased (n t=8.254, 5.962, 5.510, n P<0.05).n Conclusion:Tiam 1 is highly expressed in breast cancer cells. Down-regulation of Tiam 1 expression can inhibit tumor proliferation and metastasis of breast cancer cells.