Intratracheal Administration of Recombinant Human Keratinocyte Growth Factor Promotes Alveolar Epithelial Cell Proliferation during Compensatory Lung Growth in Rat

AhR‑E2F1‑KGFR signaling is involved in KGF‑induced intestinal epithelial cell proliferation

Keratinocyte growth factor (KGF) stimulates intestinal epithelial cell proliferation upon binding to the KGF receptor (KGFR). The activated aryl hydrocarbon receptor (AhR) serves an important role in the development of tissues by promoting the expression of AhR receptors, which can regulate cell proliferation. In the present study, the signaling pathway between AhR and KGFR in investigated with regards to KGF-induced intestinal epithelial cell proliferation. Male C57BL/6J wild type and AhR^−/− mice, were randomized into four groups: Control, KGF, AhR^−/− + KGF and AhR^−/− (n=6 per group). The small bowel was harvested on day 5 post-treatment. LoVo cells were used to study signaling pathways in vitro and were divided into the following four treatment groups: DMSO, KGF, KGF + small-interfering (si)AhR and siAhR. In vivo, knockdown of AhR mRNA transcripts may abolish KGF-induced intestinal epithelial cell proliferation. Furthermore, KGFR expression was downregulated following knockdown or silencing of AhR expression in vivo and in vitro. The present study identified that the transcription factor E2F1 could regulate KGFR expression, and that siAhR treatment led to reduced expression of E2F1 in the nucleus and inhibited KGF-induced cell proliferation. In conclusion, the current results demonstrated that the AhR-E2F1-KGFR pathway is involved in KGF-induced intestinal epithelial cell proliferation.

Keratinocyte Growth Factor Gene Electroporation into Skeletal Muscle as a Novel Gene Therapeutic Approach for Elastase-Induced Pulmonary Emphysema in Mice

Pulmonary emphysema is a progressive disease with airspace destruction and an effective therapy is needed. Keratinocyte growth factor (KGF) promotes pulmonary epithelial proliferation and has the potential to induce lung regeneration. The aim of this study was to determine the possibility of using KGF gene therapy for treatment of a mouse emphysema model induced by porcine pancreatic elastase (PPE). Eight-week-old BALB/c male mice treated with intra-tracheal PPE administration were transfected with 80 μg of a recombinant human KGF (rhKGF)-expressing FLAG-CMV14 plasmid (pKGF-FLAG gene), or with the pFLAG gene expressing plasmid as a control, into the quadriceps muscle by electroporation. In the lung, the expression of proliferating cell nuclear antigen (PCNA) was augmented, and surfactant protein A (SP-A) and KGF receptor (KGFR) were co-expressed in PCNA-positive cells. Moreover, endogenous KGF and KGFR gene expression increased significantly by pKGF-FLAG gene transfection. Arterial blood gas analysis revealed that the PaO₂ level was not significantly reduced on day 14 after PPE instillation with pKGF-FLAG gene transfection compared to that of normal mice. These results indicated that KGF gene therapy with electroporation stimulated lung epithelial proliferation and protected depression of pulmonary function in a mouse emphysema model, suggesting a possible method of treating pulmonary emphysema.