Abstract:

Objective To explore the influence of murine double minute 2 （MDM2） on epithelial mesenchymal transition （EMT） of human breast cancer cells and its molecular mechanism. Methods Western blotting method was performed to examine the protein expressions of MDM2 and EMT-related proteins （Ecadherin， N-cadherin and Vimentin） in human breast cancer cell lines MCF7， MDA-MB-231 and MDA-MB-435. The optical microscope was used to observe the morphological changes at 36th hour after transiently transfection of MCF-7 cells with empty plasmid （pcmv） or MDM2 overexpression plasmid （pcmv-MDM2） and MDA-MB-231 cells with three different interference plasmids. Meanwhile， the expressions of MDM2 and EMT related molecular markers were measured by Western blotting and immunofluorescence assays， respectively. The Western blotting and realtime quantitative PCR were used to evaluate the protein and mRNA level changes of Snail1 and Twist in MCF-7， MDA-MB-231 cells after overexpression of MDM2.
Results MCF-7 cells displayed decreased protein levels of E-cadherin and its morphology changed from tightly packed colonies to spindleshaped growth after overexpression of MDM2. MDA-MB-231 cells exhibited reduced levels of Vimentin and N-cadherin and its morphology changed from fibroblast-like growth to cobblestonelike colonies after the knockdown of MDM2. Both the protein and mRNA levels of Snail1 and Twist increased after overexpression of MDM2 in MCF-7 and MDA-MB-231 cells. Conclusion MDM2 can promote the EMT in human breast cancer cells with the possible meachism of up-regulating the expressions of Snail1 and Twist.