Interleukin-6 Regulates Proliferation Of Human Umbilical Vascular Smooth Muscle Cells Via STAT3/Oct-1/ATM

Vascular smooth muscle cells(VSMCs)are located in the middle layer of the blood vessel wall.The main function is contraction,and their proliferation rate is extremely low.The abnormal proliferation and migration of VSMCs are the pathological basis of many cardiovascular diseases,so exploring the molecular mechanisms that affect the proliferation and migration of VSMCs is contributed to reveal the pathogenesis of cardiovascular diseases.At present,many studies have found that cardiovascular diseases are often accompanied by up-regulation of inflammatory factors,and the increased inflammatory factors can regulate cardiovascular diseases by changing cell functions.Recent studies have shown that interleukin 6(IL-6)is up-regulated in patients with various cardiovascular diseases,and it plays an important role in regulating vascular cell function,but the molecular mechanism is still unclear.In this study,we explored the effect of IL-6 on the proliferation and migration of human umbilical vascular smooth muscle cells(HUVSMCs)and explored its molecular mechanism.Firstly,to explore the effect of IL-6 on the proliferation of HUVSMCs,HUVSMCs were treated with IL-6,and three IL-6 concentrations were set at5 ng/m L,10 ng/m L,20 ng/m L,and three acting periods were set as 24 h,48 h,and 72 h,respectively.Then bromodeoxyuridine(Brd U)kit,cell count kit 8(CCK8)and 5-ethynyl-2-deoxyuracil riboside(Ed U)imaging were used to detect the effect of IL-6 on the proliferation of HUVSMCs.To explore the effect of IL-6 on the migration of HUVSMCs,scratch healing was used to detect the effect of IL-6 on the migration ability of HUVSMCs.Secondly,to explore the mechanism of IL-6 mediated proliferation of HUVSMCs,western blot was used to detect the expression of signal transducer and activator of transcription 3(STAT3)phosphorylation at Ser727,Octamer transcription factor-1(Oct-1)and ataxia telangiectasia mutated(ATM).Thirdly,the position of Oct-1 in cells was detected by immunofluorescence cytochemistry.Fourthly,specific small interference RNA(siRNA)technology was used to inhibit the expression of Oct-1,and then the effects of Oct-1 on the proliferation of HUVSMCs were detected by CCK8 and Ed U imaging technology.Finally,to verify that IL-6 regulated HUVSMC proliferation via Oct-1,IL-6 was added after inhibiting the expression of Oct-1,and the proliferation of HUVSMCs was detected again using CCK8 and Ed U imaging technology.The results showed that:(1)IL-6 significantly promoted the proliferation and survival of HUVSMCs,and the effect was most obvious when the concentration was 20 ng/m L at 48 h,but IL-6 had no significant effect on the migration capacity of HUVSMCs;(2)IL-6(20 ng/m L)activated STAT3 phosphorylation at Ser727 at 15 and 30 min,increased Oct-1 at 6,12,24 h,and enhanced ATM expression at 24 h.(3)The results of immunofluorescence cytochemistry analysis showed that Oct-1 was localized in the nuclei of HUVSMCs when treated by IL-6 for 6 h and 24 h,and a part of Oct-1translocated in cytoplasm treated for 12 h by IL-6.(4)The results of siRNA revealed that inhibition of Oct-1 expression can significantly inhibit IL-6 and ATM expression.(5)Cell proliferation and viability were decreased under the inhibition of Oct-1 expression,and IL-6 reversed the suppression of cell proliferation.In conclusion,we classified that IL-6 induced the proliferation of HUVSMCs through the following pathway.IL-6 activated STAT3 phosphorylation at Ser727,enhanced Oct-1 and ATM expression,and subsequently induced the HUVSMC proliferation.This study provides a new clue for the mechanical treatment of cardiovascular disease.