A novel highly metastatic MDA-MB-231HM cells, derived from MDA-MB-231, was established in our institute. RT-PCR, real-time PCR and Western blot showed that AF1Q gene was differentially expressed between highly metastatic MDA-MB-231HM cells and its parental MDA-MB-231 cells. However, its molecular mechanisms in
breast cancer metastasis remain to be characterized. To investigate the effects of AF1Q on the progression of human
breast cancer cells, in the present study, recombinant expression plasmid vectors of the human AF1Q gene was transfected into MDA-MB-231 cells. We demonstrated that AF1Q overexpression enhanced the in vitro proliferation and invasive potential of
breast cancer cells. Focused microarray analyses showed that 22 genes were differentially expressed between AF1Q transfected cells and its parental counterparts.
Integrin alpha3, accompanied by up-regulation of Ets-1 and MMP-2, significantly enhanced the in vitro invasive potential of human
breast cancer cells mediated by AF1Q.
Estrogen-responsive ring finger
protein gene (EFP), also played a role in the enhancement of in vitro proliferation of human
breast cancer cells mediated by AF1Q, accompanied by down-regulation of 14-3-3delta. The association was
ERalpha independent. These results were further demonstrated by RNA interference (RNAi) experiment in vitro. In in vivo study, we also demonstrated that AF1Q transfected
breast cancer cells grew much faster and had more pulmonary
metastases than vector-transfected or its parental counterparts. On the contrary, AF1Q knockdown cells grew slower and had less pulmonary
metastasis. Similar effects of AF1Q on
integrin alpha3, Ets-1, MMP-2, EFP, and 14-3-3delta expression observed in vitro studies were also found in the in vivo study. Taken together, these results provide functional evidences that overexpression of AF1Q leads to a more progression in human
breast cancer, at least in part, through regulating the
integrin alpha3, Ets-1, MMP-2, EFP, and 14-3-3delta expression.