Er¦Á And Her-2 Receptor In The Experimental Study Of The Pathway Of Human Breast Cancer Cell Lines And Matrix Metalloproteinase Protease Significance In The Prognosis Of Node Negative Breast Cancer

Part I: The signal transduction pathway of ER a mediated inductionof HER2 in MDA-MB-435 human breast cancer cells Objective To explore the interaction between ERa and HER2 in the pathogenesis of breast cancer.Methods Human ERα cDNA was reintroduced into MDA-MB-435 cells by stable transfection. In the in vitro study RT-PCR and western blotting analysis were performed to assess ERα mediated HER2 by E2 and the role of AP-1 in the interaction between HER2 and ERα was also studied. To confirm the role of AP-1 antisense blockage experiment was conducted with antisense DNA oligonucleotides(AODs) to c-jun. The effects of E2 and/or growth factor (heregulin) on the cell proloiferation was detected with standard MTT. Human breast cancer was implanted orthotopically as intact tissue into nude mice to further test the results from in vitro study.Results With 4-hours treatment of E2(10nM) the HER2 mRNA or protein expression was significantly higher in the MDA-MB-435/ERα compared with the parental cells or mock transfected cells (P<0.05 ) . Estradiol(10nM) can increase the expression of HER2/neu in ER α transfectants time dependently at both mRNA and protein level. The HER2 mRNA expression increased after 2-hour treatment and at its higheat at 5 hours of treatment(2.5 folds of mock transfected cells). The HER2 protein expression increased after 3-hour treatment and at its higheat at 8 hours of treatment(2.2 folds of mock transfected cells). It was also investigated in this study the relationship between c-jun and c-fos activation and up-regulation of HER2 under the treatment of E2 in the transfectants. RT-PCR and Western blotting analyses revealed that E2(10nM) upregulated c-jun and p-c-jun expression timedependently but exerted no effect on c-fos expression. Moreover, levels of c-jun and p-c-jun expression were enhanced by E2 ahead of the increase of HER2 in the transfected cells. The c-jun mRNA expression increased after 30-min treatment and at its higheat at 3 hours of treatment(3.5 folds of mock transfected cells). There is no change with regard to the total protein of c-jun, while p-c-jun were enhanced by E2 after 10-min treatment and at its higheat at 30 min of treatment(2.1 folds of mock transfected cells) Furthermore, c-jun antisense oligodeoxynucleotides also partially prevented E2-stimulated enhancement of HER2 at both mRNA and protein level,In the in vitro study growth factor can prevent the inhibitory effect of E2 in the transfectants andthis effect was also demonstrated in the in vivo study.Conclusions There might be complicated interaction between ERa and HER2pathway, the present results show that ERa mediate the induction of HER2 gene inERa transfected cells through AP-1 pathway.