Topical Sunitinib ointment alleviates Psoriasis-like inflammation by inhibiting the proliferation and apoptosis of keratinocytes

Psoriasis is a chronic auto-immune inflammation disease with skin lesions and abnormal keratinocyte proliferation. Sunitinib, a multi-targeted tyrosine kinase inhibitor, is known to selectively inhibit several growth factor receptors, including vascular endothelial growth factor receptor, platelet-derived growth factor receptor and stem cell factor. It was reported that a patient with renal cell carcinoma (RCC) whose psoriatic lesion was resolved dramatically during treatment with Sunitinib, however, the mechanism is still unclear. We applied Sunitinib ointment to treat imiquimod-induced mouse model of psoriasis and found that Sunitinib ointment could alleviate imiquimod-induced psoriasis-like inflammation and reduce the Ki67 expression, while Sunitinib ointment couldn't reduce imiquimod-induced splenomegaly of the mouse model, then we concentrated on studying the effect of Sunitinib on the proliferation and apoptosis of keratinocytes, we cultivated HaCaT cells with epidermal growth factor (HaCaT/E cells) to represent as a state of highly proliferative psoriatic keratinocytes. We found that Sunitinib could inhibit the proliferation of Hacat/E cell in a time and concentration dependent manner by influencing the expression level of cell cycle protein D1, cycle protein E1, in addition, Sunitinib could induce the apoptosis of Hacat/E cell and up-regulate the expression of poly ADP-ribose polymerase (PARP). Sunitinib down-regulated the expression of phosphorylated signal transduction and activator of transcription 3 (p-Stat3) of Hacat/E cells significantly. We conclude that Sunitinib alleviates imiquimod-induced psoriasis-like inflammation by regulating the proliferation and apoptosis of HaCaT cells through inhibiting the expression of p-Stat3.