Study Of Regulation Of Pituitary Adenomas Invasiveness By HIF-1α Under Hypoxic Microenvironment

Objective:To investigate the expression of hypoxia inducing factor-1αin pituitaryadenomas,and its relationship with the tumor invasiveness.The expression ofHIF-1αwas suppressed by RNA interference recombinant lentivirus,to observe theinvasive behavior of primary cultured pituitary adenoma cells (PACs) in the hypoxicmicroenviorment.Methods:The expression of HIF-1α,MMP-9 and VEGF were detected byimmunostaining.And the mRNA levels of HIF-1α,MMP-9 and VEGF were detectedby RT-PCR.The relationships between the above indexes and the tumor invasivenesswere analysed.The growth and immigration of the primary cultured and purifiedPACs were observed in vitro.Cell cycles were detected by flow cytometry.Theexpression of hormone receptor was detected by immunofluorescence.The sequenceof HIF-1αShRNA was designed to synthesize pRNAT-U6.2 lentivirus for stabletransfection of PACs.The interference efficiency was checked by RT-PCR andWestern-blot.The hypoxic model and invasice model in vitro (Boyden chamber) werebuilt to observe the change of HIF-1αexpression level regulated by RNAi,and theinvasiveness of PACs.Results:The positive staining of HIF-1αwas mainly distributed in the cytoplasm ofPACs and some surrouding vascular endothelial cells.HIF-1αprotein and mRNAlevel were closely correlated with the tumor invasiveness,and had no correlation withVEGF and MMP-9.Highly purified PACs were obtained in vitro.The PACs from theinvasive pituitary adenomas had strong proliferation,immigration and invasiveness.HIF-1αexpression was significantly upregulated under hypoxic condition for 24hours.PACs transfected with high titer lentivirus (5~*10~5 TU/well) were checked byWestern-blot,which showed obvious suppression of HIF-1αprotein and mRNA level.And the invasiveness of PACs was downregulated by RNAi,which had been provedby invasion test in vitro.Conclusion:Over expression of HIF-1αinduced by hypoxic stress is an essentialevent in the activation of PAC motility through alteration of invasion-relatedmolecules.Targeting the HIF-1α.Molecule may be a noval therapeutic strategy for invasive pituitary adenomas...