Study On The Expression Of IL-6/STAT3/Cyclin D1, VEGF Signaling Pathway In Uterine Leiomyomas

Background:Uterine leiomyoma(UL) is the most common benign tumor in women.Recently, with the wide application of ultrasound diagnostic techniques,the incidence of UL is up to 77%,but the underlying pathogenesis remain unclear.At present,it is believed generally that UL is estrogen and progesterone-dependent tumor,and in recent years, studies have shown that roles steroid hormone played in cell proliferation and differentiation were regulated by growth factors.The JAK/STAT3 pathway was involved in the signaling transduction of growth factors,if the pathway was impaired or activated abnormally,it may make a marked effect on the development and prognosis of many diseases.The STAT3 is an important member of the signal transducers and activators of transcription families and activated by tyrosine phosphorylation,then formed dimer and transfered into intranuclear under the stimulus of cytokines and growth factors.The activated STAT3 binds to specific DNA site to regulate gene transcription,playing an important role in controlling apoptosis and angiopoiesis. CyclinD1 is a downstream regulatory gene of STAT3 involved in the regulation of cell cycle,its abnormal expression will accelerate cell cycles and result in lasting cell proliferation.VEGF is one of the most important angiogenesis factors.It has been reported that STAT3 can bind to the sites existing in the promoter region of VEGF and regulate the expression of VEGF directly resulting in the tumor neovascularization. IL-6 is a multipotent cytokine involved in the regulation of immune reactions, hematopoiesis,cell proliferation and differentiation.The multipotency of IL-6 is mediated by binding to cell surface IL-6 receptor.In this process,IL-6 can activate specific signaling molecules and regulate the expression of induced genes such as Jak1,Jak2 and Tyk2 of Jaks families;STAT3 and STAT1 of STATS families as well as a variety of signaling molecules of Ras pathway participating in the signal transduction of IL-6 in target cells,which forming the two signaling pathway of IL-6: Ras/MAPK and JAK/STAT pathway.In JAK/STAT pathway,IL-6 activated STAT3 mainly,furthermore,it is well known that abnormal activation of STAT3 has a direct correlation with the expression of CyclinD1 in some tumors such as head and neck cancer.Although UL is a benign tumor,it has some characteristics of malignant tumor such as the high expression of VEGF,survivin and bcl-2,but there is little information obtained about IL-6/STAT3/CyclinD1,VEGF pathway in UL.The study was performed to investigate the expression of IL-6/STAT3/CyclinD1,VEGF signaling molecules in UL in order to give evidence for studying the pathogenesis of uterine leiomyomas further.Objective:1) To investigate the expression of IL-6/IL-6R and STAT3/CyclinD1,VEGF in uterine leiomyomas and homologous normal myometriums.2) To investigate the serum level of IL-6 in patients with uterine leiomyoma.3) To explore the role IL-6/STAT3/CyclinD1,VEGF signaling molecules played in the pathogenesis of uterine leiomyomas.Methods:1) To investigate the expression of STAT3 and phosphorylation STAT3 in uterine leiomyomas and homologous normal myometriums,the RT-PCR and IHC were used. 2) RT-PCR was used to examine the expression of CyclinD1 and VEGF in uterine leiomyomas and homologous normal myometriums.3) Western blot,IHC and RT-QPCR were used to examine the expression of IL-6 in uterine leiomyomas and homologous normal myometriums.4) Western blot and RT-PCR were used to examine the expression of IL-6R in uterine leiomyomas and homologous normal myometriums.5) To detected the serum level of IL-6 in patients with leiomyomas and healthy reproductive age women,ELISA was used.Results:1) The expression of STAT3 and phosphorylation STAT3 in uterine leiomyomas is higher than that in homologous normal myometriums,P＜0.05.2) The expression of CyclinD1 and VEGF is elevated in uterine leiomyomas when compared with homologous normal myometriums,P＜0.05.3) At both gene and protein levels,the expression of IL-6 in homologous normal myometriums is higher than that in uterine leiomyomas,P＜0.05.4) There is no significant difference in the expression of IL-6R between uterine leiomyomas and homologous normal myometriums,P＞0.05.5) There is no significant difference in the serum level of IL-6 between patients with leiomyomas and healthy reproductive age women,P＞0.05.Conclusion:The expression of STAT3 and its downstream genes such as CyclinD1,VEGF in uterine leiomyomas were significantly higher than that in normal myometriums. STAT3 can activate downstream genes Cyclin D1 and VEGF,which involved in the pathogenesis of leiomyomas by regulating the cell cycle,inhibiting cell apoptosis and promoting local angiogenesis.Although IL-6 is a cytokine having a close relationship with many tumors,and may exert its biological effects by activating STAT3,the study has found that low expression of IL-6 in leiomyomas was inconsistent with high expression of STAT3,STAT3 was activated by other growth factor pathway probably in uterine leiomyomas.