1型胰岛素样生长因子受体在髓母细胞瘤细胞增殖中的作用

The role of insulin-like growth factor 1 receptor in the cell proliferation of human medulloblastma

目的研究1型胰岛素样生长因子受体（IGF-1R）在髓母细胞瘤中的表达及其对细胞增殖的作用。方法荧光定量PCR检测髓母细胞瘤肿瘤标本IGF-1R表达，CCK-8法测定IGF-1R特异性阻断剂NVP—ADW742对髓母细胞瘤Doay细胞增殖抑制作用，并检测其对细胞凋亡的影响，Western blot免疫印迹法检测了AKT磷酸化蛋白表达变化。结果髓母细胞瘤肿瘤标本中的IGF-1RmRNA的相对含量明显高于低级别星形胶质瘤；NVP-ADW742能通过诱导细胞凋亡抑制Doay细胞的增殖，NVP-ADW742主要是通过下调AKT磷酸化蛋白表达而起作用。结论IGF-1R在髓母细胞瘤的细胞增殖中起着重要作用。

Objective Insulin - like growth factors and their receptor （ IGF - 1 R） have been implicated in cancer pathophysiology. The purpose of this study was to investigate the IGF - 1R expression in medulloblastoma, and determine the mechanism of action of IGF - 1R in the cell proliferation. Method The brain tumor sample of 13 medulloblastoma and 8 low grade astrocytoma were freshly collected from surgical specimen. Total cell RNA was isolated with Trizol. The IGF - IR mRNA was determined by real- time quantitative RT - PCR using SYBR Green. Doay cell line was cultured in Eagle＇s MEM supplemented with 10% fetal bovine serum. Fluorescence intensity of IGF- 1R staining was determined using flow eytometer in Doay cell line. Doay cells were treated with the indicated concentration of specific IGF - IR kinase inhibitor, NVP - ADW742, in 96 - well culture plates for 48 hours. Then cell Counting CCK - 8 was used to each well for 2 hours. Absorbanee readings at a wavelength of 450 nm and reference wavelength of 650 nm were taken on a spectrophotometer. Doay cells were incubated in the presence of different concentration of NVP - ADW742 and apoptotic rate was determined by flow cytometry using annexin V. The phospho- AKT protein was detected by Western blot in Doay cells exposed with NVP- ADW742. Results The relative level of IGF - 1R mRNA expression was significantly higher than that in low grade astrocytoma. Flow cytometer showed that the cell surface protein IGF - 1R expressed in medulloblastoma cell line Doay. Exposure of Doay cells to NVP - ADW742 in different concentration resulted in significant growth inhibition of Doay cells. And the results showed that a dose - dependent proliferation inhibitation was demonstrated in Doay cells. Western blotting detection showed that phospho -AKT protein decreased in Doay cells upon NVP - ADW742 treatment. Conclusions The expression of IGF - 1R plays an important role in development of medulloblastoma by promoting abnormal tumor cellular proliferation. NVP - ADW742 inhibits IGF - 1 - mediated receptor activation and the induction of apoptosJs by NVP - ADW742 in Doay cells might due to the downregulation of phospho - AKT protein.