Abstract: Objective To investigate the key mechanisms of HIF-1α on the Angiogenesis in malignant meningioma. Methods The mRNA and protein expression levels of HIF-1α and IGF1R in normal placenta tissues, benign meningioma tissues (WHO grade Ⅰ) and recurrent meningioma tissues (WHO grade Ⅱ-Ⅲ) were determined by qPCR and immunohistochemistry. Dual-luciferase gene reporter assay and ChIP assay were used to verify the direct interaction between HIF-1α and IGF1 gene regulatory region. Knockdown of HIF-1α expression in anaplastic meningioma CRL3370 cells were performed by using HIF-1α shRNA. ELISA was used to determine the secretion of IGF1 and VEGF in the CRL-3370 cells after HIF-1α knock-down. Western blotting was used to determine the expression levels of p-IGF1Rβ, IGF1Rβ and VEGFR2 in CRL-3370 cells. A co-cultured system of CRL-3370 cells and HUVEC2 was established, and the expression of HIF-1α in CRL-3370 cells was induced by hypoxia condition and followed by the shRNA knocking-down. CCK8 assay was used to determine the cell proliferation ability of HUVEC2. qPCR assay was used to determine the VEGF, ANGP1 and MMP2 mRNA expression levels in HUVEC2 cells. Wound-healin assay and transwell assay were used to determine the migration and invasion ability of HUVEC2 cells. Results The mRNA and protein expression levels of HIF-1α and IGF1R in meningioma tissues increased as the meningioma progressed from benign (WHO grade Ⅰ) to reccurrent (WHO grade Ⅱ-Ⅲ) (P < 0. 01). The luciferase activity in the IGF1 group was significantly up-regulated when compared with that in the Control group. The luciferase activity in the deletion site-4 group was significantly inhibited when compared with that in the IGF1 group (P < 0. 05). ChIP experiment showed that the DNA content of site-4 in the HIF-1α group was significantly higher than that in the corresponding IgG group (P< 0. 05). The levels of secreted IGF1 and VEGF in the HIF-1α shRNA group were significantly reduced when compared with those in the shRNA NT group. The intracellular expression levels of p-IGF1Rβ, IGF1Rβ and VEGFR2 were down regulated. The cell proliferation ability of HUVEC2 in the co-cultured system was reduced and the mRNA expression levels of VEGF, ANGP1 and MMP2 were decreased. Cell migration and invasion abilities were reduced (P< 0. 05). Conclusion HIF-1α is up-regulated and directly enhances the IGF1 / IGF1R signaling to promote the angiogenesis in HUVEC2 and metastasis of recurrent meningioma. 

Key words: meningiomas, HIF-1α, IGF1 / IGF1R axis, angiogenesis