Ruxolitinib attenuates intimal hyperplasia via inhibiting JAK2/STAT3 signaling pathway activation induced by PDGF-BB in vascular smooth muscle cells

Cardiovascular diseases are associated with proliferation and phenotypic switch. Platelet-derived growth factor-BB (PDGF-BB) is a major initiating factor for proliferative vascular diseases, such as neointimal lesion formation, restenosis after angioplasty, and atherosclerosis. Ruxolitinib, a potent Janus kinase (JAK) 1 and 2 inhibitor, has been reported to significantly block the proliferation-related signaling pathway of JAK2/signal transducers and activators of transcription 3 (STAT3) and harbor a broad spectrum of anti-cancer activities, including proliferation inhibition, apoptosis induction, and anti-inflammation. However, the role of ruxolitinib in regulating PDGF-BB-induced VSMC proliferation remains to be elucidated. Thus, this study investigates the role of ruxolitinib in regulating PDGF-BB-induced VSMC proliferation and its underlying mechanisms.

Our findings suggest that ruxolitinib inhibits VSMC proliferation in vivo and in vitro by suppressing the activation of the JAK2/STAT3 signaling pathway. Therefore, ruxolitinib has a therapeutic potential for proliferative vascular diseases.

In vivo, the medial thickness of the carotid artery was evaluated using a mouse carotid ligation model, ruxolitinib was administered orally to the mice every other day, and the mice were euthanized on day 28 to evaluate the therapeutic effects of ruxolitinib. Cell proliferation markers were measured using real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) and western blotting. In vitro, VSMCs were treated with ruxolitinib with or without PDGF-BB at an indicated time and concentration. Cell proliferation and apoptosis were measured using Cell Counting Kit-8 assay, MTS assays and flow cytometry. The JAK2/STAT3 signaling pathway involved in the effects of ruxolitinib on VSMCs was detected by western blotting with the specific pathway inhibitor AG490.

In vivo, ruxolitinib significantly decreased the ratio-of-intima ratio (I/M ratio) by inhibiting the expression of PCNA and cyclinD1 (p <0.05). In vitro, ruxolitinib inhibited PDGF-BB-induced VSMC proliferation compared with the PDGF-BB treatment group (p <0.05). In addition, ruxolitinib inhibited the PDGF-BB-induced activation of the JAK2/STAT3 signaling pathway and decreased the expression of proliferation related-proteins cyclinD1 and PCNA in VSMCs (p <0.05).