Abstract
Polypeptide growth factors not only stimulate growth and regulate differentiation of various cell types, but some of them also exert cell-protecting activity through multiple signaling pathways. Utilization of such growth factors thus maybe helpful for preventing cellular damage induced by irradiation. Here we assessed the potential of fibroblast growth factor-1 (FGF1) and FGF7 (also known as keratinocyte growth factor: KGF) for preventing ultraviolet (UV) irradiation-induced apoptosis of HaCaT cells, human immortalized keratinocytes. HaCaT cells were exposed to UV-B (10 mJ/cm2) and 24 h later the resulting apoptotic effect was evaluated by the reactivity of the cell surface with annexin V using a flowcytometer. Compared to control HaCaT cells, the cells pretreated with FGF1 or FGF7 in the presence of heparin showed significant reduction in the number of the annexin V positive cells in the FGF-dose dependent manner. The anti-apoptotic activity of FGF1, that has wider receptor specificity than FGF7, was larger than that of FGF7. Similarly, whereas expression levels of apoptosis-related genes, c-jun and IL-6, kept increasing in the control HaCaT cells until 24 h after irradiation by UV-B, those in the cells pre-treated with FGF1 or FGF7 were suppressed; revealing FGF1 as more effective than FGF7. The results indicate that both FGF1 and FGF7 are capable of suppressing UV-induced apoptosis of HaCaT cells, and suggest that FGF1 protects various cell types from UV-induced apoptosis. The signaling mechanism underlying this activity is being investigated.
