Effect of expressional alteration of KAI1 on breast cancer cell growth, adhesion, migration and invasion.

KAI1, also known as CD82, is a candidate metastasis suppressor gene and has been indicated in the disease progression of certain solid tumours, including those of breast cancer. The present study aimed to investigate the importance of KAI1 as a potential metastasis suppressor in breast cancer cells. MDA-MB-231 and MCF-7 sublines with different patterns of KAI1 expression were created by way of anti-KAI1 transgene or transfection of KAI1 expression construct. Cell adhesion was markedly increased in cancer cells showing increased expression of KAI1 (MCF-7(KAI1EXP), p=0.021 vs. control cells), while it was significantly reduced in the KAI1 knockout subline, MDA-MB-231(KAI1KO) (p=0.002 and 0.0004, respectively). Significant increase of cell migration of MCF-7(KAI1EXP) cells (p=0.024 vs. control) and restricted motility of MDA-MB-231(KAI1KO) cells (p=0.003) were observed. Furthermore, MCF-7(KAI1EXP) cells also showed reduced cell invasion (p=0.022), while MDA-MB-231(KAI1KO) cell line showed a significant increase in invasion (p=0.0063 and p=0.007, respectively). KAI1 did not affect cell growth. It is concluded therefore that KAI1 plays an important role in cell adhesion, invasion and migration of breast cancer cells, in vitro, and is a potential metastasis suppressor gene in breast cancer.