Increased production of human fibroblast growth factor 17 in Escherichia coli and proliferative activity in NIH3T3 cells.

Fibroblast growth factor 17 (FGF17) is a novel member of the FGFs family, which is essential for cell development, tissue repair, tumor growth and invasion. The aim of the current study was to obtain a high expression level of recombinant human FGF17 (rhFGF17), including soluble proteins and inclusion bodies. An optimized rhFGF17 cDNA sequence was cloned into a pET3a vector, then the pET3a‑hFGF17 vector was transformed into BL21(DE3)pLysS Escherichia coli cells. Expression was induced by optimizing the conditions using isopropyl β‑D‑1‑thiogalactopyranoside (IPTG) and it was confirmed that a 24‑h exposure to 0.8 mM IPTG at 16˚C provided the optimal condition for soluble hFGF17. Furthermore, for the inclusion bodies, the optimal condition was a 4‑h exposure to 0.4 mM IPTG at 37˚C. Two forms of rhFGF17 protein were purified by heparin affinity and SP Sepharose Fast Flow chromatography. MTT assays demonstrated that the purified rhFGF17 exerted an important effect on the proliferative activity of NIH3T3 cells, although there was no significant difference when compared with standard rhFGF17. Thus, an optimal and economic expression system was created in the present study for rhFGF17 in E. coli. This expression strategy enables the preparation of sufficient and highly bioactive rhFGF17 for further investigation of underlying mechanisms.