Background: In a previous study, we reported that keratinocyte growth factor (KGF) produced a rapid increase in the motility of ER-positive breast cancer cells. Others have demonstrated that KGF treatment in rodent species produces rapid mammary ductal hyperplasia. Epithelial cells do not produce KGF; thus, in the present study, MCF-7 cells were stably transfected with a KGF-expressing vector and the motility and morphology of the transfected, non-transfected and empty vector cell lines compared.
Materials and methods: A mammalian expression vector containing a KGF cDNA was transfected into MCF-7/beta cells, and two stable clones (MCF-7/beta/KGF-T8 and MCF-7/beta/KGF-T9) were identified. Western blotting of conditioned medium from these clones was used to confirm the expression of KGF. The motility of wild-type and KGF-transfected MCF-7 cells was compared using time-lapse videomicroscopy and a cell culture wounding model which examined cell migration over a period of 1-3 days.
Results: The Western blots demonstrated that the expression of KGF in both the MCF-7/beta/KGF-T8 and MCF-7/beta/KGF-T9 cell lines was higher than the wild-type and MCF-7/beta cell lines. The cell proliferation and migration distance was significantly greater for both KGF-transfected MCF-7 cell lines than the wild-type and MCF-7/beta cell lines under the same experimental conditions. Further, changes in motile morphology were observed in both the MCF-7/beta/KGF-T8 and MCF-7/beta/KGF-T9 cell lines. In addition, the MCF-7/beta/KGF-T8 clone was found to produce much larger tumors than both the MCF-7/beta/KGF-T9 and EV clones in mouse xenografts. These results indicated that autocrine production of KGF in the KGF-transfected MCF-7 cell lines enhanced cell migration, migration-related morphology and xenograft tumor growth.
Conclusion: KGF-transfected MCF-7 cells displayed a much greater motility than non-transfected cells, confirming the KGF motility enhancement effect which we previously reported. The use of KGF-transfected breast cancer cells in the xenograft model may help to study the mechanism of KGF-mediated cell motility and to identify specific KGF antagonists that may be used to prevent or impede KGF-mediated metastatic progression.