Objective: To investigate the relationship between LKB1 gene and invasion of breast cancer cells.
Methods: Human breast cancer cells of the line MDA-MB-435 were cultured and transfected with plasmids with or without LKB1 gene. The clone of the transfected MDA-MB-435 cells with high expression of LKB1 was called MDA-MB-435/LKB1 (H), and that with low expression of LKB1 was called MDA-MB-435/LKB1 (L). The MDA-MB-435 cells transfected with blank vector was called MDA-MB-435/vec. MDA-MB-435 cells without transfection were used as controls. RT-PCR was used to detect the mRNA expression of the invasion-related factors of breast cancer: matrix metalloproteinase (MMP)-2, MMP-9, vascular endothelial growth factor (VEGF), and basic fibroblast growth factor (bFGF), and Western blotting was used to detect the protein expression of these factors. Gelatin zymography was used to expression of the secretive MMP-2 and MMP-9. Transwell test was used to examine the membrane penetration of the different MDA-MB-435 cells.
Results: The invasion rate was (47.6 +/- 1.3)% in the MDA-MB-435 cells, (45.6 +/- 1.2)% in the MDA-MB-435/vec cells, both significantly higher than those of the MDA-MB-435/LKB1 (H) and MDA-MB-435/LKB1 (L) cells [(18.1 +/- 1.0)% and (22.4 +/- 1.8)% respectively, all P < 0.01], with significant difference between the latter 2 groups (P < 0.05). The mRNA expression and protein expression of MMP-2, MMP-9, VEGF, and b-FGF were all significantly lower in the MDA-MB-435/LKB1 cells. Gelatin zymography showed that the secretive MMP-2 and MMP-9 were expressed at the protein level significantly lower in the MDA-MB-435/LKB1 cells.
Conclusion: LKB1 gene inhibits the invasion of breast cancer cells.