KGF facilitates repair of radiation-induced DNA damage in alveolar epithelial cells

Abstract

Administration of exogenous keratinocyte growth factor (KGF) prevents or attenuates several forms of oxidant-mediated lung injury. Because DNA damage in epithelial cells is a component of radiation pneumotoxicity, we determined whether KGF ameliorated DNA strand breaks in irradiated A549 cells. Cells were exposed to 137Cs gamma rays, and DNA damage was measured by alkaline unwinding and ethidium bromide fluorescence after a 30-min recovery period. Radiation induced a dose-dependent increase in DNA strand breaks. The percentage of double-stranded DNA after exposure to 30 Gy increased from 44.6 +/- 3.5% in untreated control cells to 61.6 +/- 5.0% in cells cultured with 100 ng/ml KGF for 24 h (P < 0.05). No reduction in DNA damage occurred when the cells were cultured with KGF but maintained at 0 degree C during and after irradiation. The sparing effect of KGF on radiation-induced DNA damage was blocked by aphidicolin, an inhibitor of DNA polymerases-alpha, -delta, and -epsilon and by butylphenyl dGTP, which blocks DNA polymerase-alpha strongly and polymerases-delta and -epsilon less effectively. However, dideoxythymidine triphosphate, a specific inhibitor of DNA polymerase-beta, did not abrogate the KGF effect. Thus KGF increases DNA repair capacity in irradiated pulmonary epithelial cells, an effect mediated at least in part by DNA polymerases-alpha, -delta, and -epsilon. Enhancement of DNA repair capability after cell damage may be one mechanism by which KGF is able to ameliorate oxidant-mediated alveolar epithelial injury.

Biomimetic Delivery of Keratinocyte Growth Factor upon Cellular Demand for Accelerated Wound Healing in Vitro and in Vivo

“…In contrast, the number of cells in control samples decreased throughout time likely due to cell death. In agreement with previous studies, [15][16][17][18][19][20][21] these results suggest that in addition to promoting proliferation, KGF, P-KGF, and PL-P-KGF may also promote cell survival.…”

Keratinocyte growth factor supports pulmonary innate immune defense through maintenance of alveolar antimicrobial protein levels and macrophage function

“…KGF is a potent epithelial mitogen and differentiation factor, produced almost exclusively by cells of mesenchymal origin, that acts predominantly on epithelial cells through ligation of an alternatively spliced tyrosine kinase receptor, FGF receptor 2 (FGFR2) type IIIb (7,12,30). Exogenously administered KGF has been reported to protect the lungs of animals from a variety of subsequent insults, including acid instillation (44), hyperoxia (25), bleomycin (9), radiation exposure (36,46), LPS instillation (14), bacterial challenge (39), and ventilatorinduced injury (40). The protective effects of KGF have been linked to stimulation of alveolar type II epithelial cell (AECII) proliferation and differentiation, inhibition of apoptosis, attenuation of DNA damage, and induction of factors that reduce oxidative stress (11).…”

Role of the pulmonary epithelium and inflammatory signals in acute lung injury

“…The role of IL-1β in epithelial repair also appears to be mediated by EGF and TGF-α, as blockade of this pathway abrogates epithelial cell migration in vitro [96]. KGF has been shown to induce alveolar type II proliferation in vitro and in vivo, and it reduces disease severity and mortality of murine models of ALI [100][101][102][103][104][105][106][107]. It also appears to function through a common pathway via EGFR [97].…”