ABSTRACT
<p><b>OBJECTIVE</b>To explore the inhibitory effect of KAI1 gene on breast cancer cell growth in vitro.</p><p><b>METHODS</b>Highly metastatic human breast cancer cell line MDA-MB-231 was transfected with pCMV-KAI1 or mock transfected plasmid pCMV with lipofectamine. Western blot was used to determine the expression of target protein of KAI1. The proliferative ability of cells was tested by MTT assay and colony-forming test. The cell cycle pattern was assayed by flow cytometry. The metastatic ability was investigated by cell adhesion and invasion assays.</p><p><b>RESULTS</b>A stable cell clone transfected with KAI1 gene was obtained and over-expression of KAI1 protein was observed. There was a significant decline in cell proliferative ability of pCMV-KAI1 transfected MDA-MB-231 cells in comparison with the mock-transfected ones and non-transfected ones, revealed by MTT assay and colony-forming test (P < 0.05). The ability of adherence and invasion of pCMV-KAI1 transfected cells was significantly reduced in comparison with the other two groups (P < 0.05). Also, flow cytometry analysis revealed that in KAI1 transfected cell group the number of cells in G0/G1 phase increased markedly from 36.78% +/- 0.61% to 64.00% +/- 7.56%, while the number of cells in G2/M phase decreased from 17.88% +/- 0.76% to 7.63% +/- 0.60%, comparing with the non-transfected ones.</p><p><b>CONCLUSION</b>KAI1 gene suppresses the invasive ability of human breast cancer cells in vitro and may inhibit the proliferative ability by changing the cell cycle pattern.</p>