Thermal injuries induce gene expression of endogenous c-fos, c-myc and bFGF in burned tissues

Objective To investigate the expression sequence and distribution characteristics of the protooncogenes c-fos, c-myc and endogenous basic fibroblast growth factor (bFGF) genes in burned tissues, and to explore the possible effects of changes in these genes' functions on wound healing. Methods Partial-thickness burns of 30% TBSA were established on backs of Wistar rats. In situ hybridization and histological methods were used to detect expression of c-fos, c-myc and bFGF genes in normal and burned tissue at 3 h, 6 h, 1 d, 3 d, 7 d and 14 d postburn. Results Although expression of c-fos and c-myc genes and bFGF gene could be found in normal skin, the expression of all three were markedly induced by burn wounds and the expression models in sequence and distribution were quite different. Expression of c-fos gene increased and peaked at 6 h. Signals were mainly localized in both nuclei of dermal fibroblasts and monocytes. The expression of bFGF gene increased at 6 h and peaked at 1 d postburn, and was distributed in the cytoplasm of fibroblasts. C-myc gene peaked 3 d postburn and was also distributed in the cytoplasm of fibroblasts. Conclusions These results indicated that thermal injury could induce the expression of c-fos, c-myc and bFGF at gene level, showing phasic control and regional distribution. The phasic expression of these genes suggests that there is an interaction between protooncogenes and bFGF, which may play an important role in wound healing. The different expressions of c-fos and c-myc play an inducing role in regulating bFGF, and in turn affect wound healing.