Expression Of HIF-1α And VEGF In Cerebellar Hemangioblastoma

Hemangioblastoma (HB) is a sort of central nervous system (CNS) tumor, which is traceable from mesoblast remnant tissue. Hemangioblastoma is benign tumor, which generally has no character of invasion. They account for 0.9% to 2.1% of all intracranial tumors, and the cerebellum, spinal cord, and brainstem are the most frequently affected sites. Hemangioblastoma may occur sporadically or in association with von Hippel-Lindau (VHL) disease. Now, the main therapeutic measure is exairesis. Cerebellar hemangioblastoma is composed of blood vessel, and its blood supply is extremely abundant. All of these increase difficulty and death rate of the operation. And, when the affected site adjoins brainstem and fourth ventricle of cerebrum. Especially when the tumor position located operation-restricted zone, we have to give up the operation. We hope find a new therapy. Most distinguished characteristic of cerebellar hemangioblastoma, which is compared to other brain tumors, is that cerebellar hemangioblastoma was highly vascularized. So, the therapy, which aim directly at tumor angiogenesis during the process of generation and development of cerebellar hemangioblastoma may be an ideal therapy.Recently, Hypoxia-inducible factor-1α(HIF-1α) was discovered as a major transcription factor, which has regulatory function in hypoxia in vivo. Vascular Endothelial Growth Factor (VEGF) is the most important factor in vivo, which can promote angiogenesis. It can directly stimulate the division growth of endothelial cell. And VEGF is most specific mitogen of vascular endothelial cell, which participate in many of physiology and pathology process. It cannot only promotes the proliferation and migration of vascular endothelial cell, but also increases vasopermeability. For the past few years, the effect of HIF-1αand VEGF become a hot topic in the occurrence and development of tumor, and the research demonstrate that HIF-1αcan promote the expression of such as VEGF gene etc, then tumor vessel appear the change of hyperplasia. HIF-1αis the central regulator of tumor angiogenesis.Objective: In this topic, we use immunohistochemical stain and RT-PCR to detect the expression of HIF-1αgene in cerebellar hemangioblastoma both in protein level and mRNA level. We want to search for the expression of HIF-1αand VEGF and their associativity in cerebellar hemangioblastoma. We hope to provide experimental data for the research of molecular mechanism of the occurrence and development of cerebellar hemangioblastoma.Methods:1 The 30 paraffin-embedded specimen of cerebellar Hemangioblastoma were collected from the department of neurosurgery at the second hospital of Hebei Medcial University from 2001 to 2006, and all of patient's clinical data are complete. All of patients had not suffered from radiotherapy and chemotherapy before they operated. And we obtain normal cerebellar tissues from 10 patients, on who was performed posterior fossa decompression (PFD) at our institution from 2005 to 2006. The 10 normal cerebellar tissues were served as controls. We obtain 5 cases freezed fresh specimens during the operative process from the department of neurosurgery at the second hospital of Hebei Medcial University from 2005 to 2006, when we obtain specimens; we immerge specimens into liquid nitrogen at once, then, preserve it in -80oC refrigerator. We obtain normal cerebellar tissues from 1 patient, on who was performed posterior fossa decompression (PFD) at our institution. The 1 normal cerebellar tissues was frozen and served as controls.2 We use immunohistochemistry technique to detect the expresseion of protein level of HIF-1αand VEGF. We execute the procedure according to illustration of kit. HIF-1αprotein and VEGF protein were classified as follows: we observe proportion of positive cell in the field of vision of 10 of high power lens (10×40) by optical microscope, then we calculate the positive cell ratio. No positive cell or positive cell less than 1% classified negative (-), 1～10% positive cell classified positive (+), 11%～50% positive cell classified middle positive (++), more than 50% positive cell classified strong positive (+++).3 We use RT-PCR technique to detect the expressed of HIF-1αmRNA and VEGF mRNA. Total RNA was isolated from harvested cells by Trizol. The obtained target gene fragment of HIF-1αand VEGF were amplified through RT-PCR reaction. The products were analyzed by 1.5% agarose gel electrophoresis followed by staining with ethidium bromide (EB). Then we observe and take photos in the viltalight lamp. We adopt LabWork system to scan each band and carry out semiquantitative analysis. Fisher exact propability and Spearman rank correlation were used for statistics.Results:1 Expression of HIF-1αprotein in cerebellar hemangioblastoma tissues: 1 sample of normal cerebellar tissues has HIF-1αto express. 28 samples of cerebellar Hemangioblastoma tissues have HIF-1αto express. The positive rate of HIF-1αwas 93.3% in cerebellar Hemangioblastoma, 10% in normal cerebellar (p<0.01).2 Expression of VEGF protein in cerebellar hemangioblastoma tissues: 1 sample of normal cerebellar tissues has VEGF to express. 29 samples of cerebellar hemangioblastoma tissues have VEGF to express. The positive rate of VEGF was 96.6% in hemangioblastoma, 10% in normal cerebellum (P < 0.01).3 Expression of HIF-1αmRNA in cerebellar hemangioblastoma tissues: none of samples of normal cerebellar tissues have HIF-1αmRNA to express. 5 samples of cerebellar hemangioblastoma tissues have HIF-1αmRNA to express. The positive rate of HIF-1αwas 100% in cerebellar Hemangioblastoma, 0% in normal cerebellar.4 Expression of VEGF mRNA in cerebellar hemangioblastoma: none of samples of normal cerebellar tissues have VEGF mRNA to express. 5 samples of cerebellar hemangioblastoma tissues have VEGF mRNA to express. The positive rate of VEGF mRNA was 100% in cerebellar hemangioblastoma, 0% in normal cerebellar tissues.5 The correlation of HIF-1αand VEGF in protein level in cerebellar hemangioblastoma is positive correlation (r=0.903).Conclusions:1 Expression of HIF-1αprotein and HIF-1αmRNA in cerebellar hemangioblastoma increase obviously.2 Expression of VEGF protein and VEGF mRNA in cerebellar hemangioblastoma increase obviously.3 Expression of HIF-1αand VEGF in cerebellar hemangioblastoma are correlative. HIF-1αmay act as an important role during the process of generation and development of cerebellar Hemangioblastoma through promoting the expression of VEGF.4 HIF-1αand VEGF may become a therapeutic target or prognostic indicator in cerebellar hemangioblastoma.