Effect of hyperthermia on invasion ability and TGF-β1 expression of breast carcinoma MCF-7 cells

The present study aimed to investigate heating-induced alterations of breast cancer cell invasion abilities and the potential mechanisms associated with TGF-β1 expression. MCF-7 cells were heated at 43, 45, 47 and 37 °C for 30 min. In vitro cell invasion ability was evaluated by matrigel invasion assay. The activity of matrix metalloproteinase (MMP)-2/9 was investigated by gelatin zymographic assays. Expression of vascular endothelial growth factor (VEGF) and transforming growth factor-β1 (TGF-β1) was investigated by immunocytochemistry and RT-PCR. Apoptosis was analysed by flow-cytometry. The invasive potential of MCF-7 cells was reduced by heating, and MMP-2/9 secretion and enzymatic activity were suppressed. Furthermore, VEGF and TGF-β1 mRNA and proteins were suppressed by hyperthermia. These results suggest that down-regulation of the expression of TGF-β1, EGF and MMPs by hyperthermia probably accounts for the inhibition of the invasive abilities of MCF-7 cells.