Department of Neurosurgery, Second Hospital of Hebei Medical College, Shijiazhuang, Hebei 050000, China.
Chin Med J (Engl). 2012 Jun;125(11):2025-31.
The level of c-Myc is closely associated with high pathological grade and the poor prognosis of gliomas. Vascular endothelial growth factor (VEGF) is the most important angiogenic factor that potently stimulates the proliferation and migration of vascular endothelial cells. This study aimed to address the biological importance of c-Myc in the development of gliomas, we downregulated the expression of c-Myc in the human glioblastoma cell line IN500 and studied the in vitro effect on cellular growth, proliferation, and apoptosis and the expression of VEGF and the in vivo effect on tumor formation in a xenograft mouse model.
IN500Δ cells were stably transfected with shRNA-expressing plasmids for either c-Myc (pCMYC-shRNA) or as a control (pCtrl-shRNA). Following establishment of stable cells, the mRNA expressions of c-Myc and VEGF were examined by reverse transcription (RT)-PCR, and c-Myc and VEGF proteins by Western blotting and immunohistochemistry. Cell-cycle progression and apoptosis were determined by flow cytometry. The in vivo effect of targeting c-Myc was determined by subcutaneous injection of stable cells into immunodeficient nude mice.
The stable transfection of pCMYC-shRNA successfully knocked down the steady-state mRNA and protein levels of c-Myc in IN500, which positively correlated with the downregulation of VEGF. Downregulating c-Myc in vitro also led to G1-S arrest and enhanced apoptosis. In vivo, targeting c-Myc reduced xenograft tumor formation and resulted in significantly smaller tumors.
c-Myc has multiple functions in glioblastoma development that include regulating cell-cycle, apoptosis, and VEGF expression. Targeting c-Myc expression may be a promising therapy for malignant glioma.
c-Myc 水平与高级别病理和胶质瘤预后不良密切相关。血管内皮生长因子（VEGF）是最重要的血管生成因子，能强烈刺激血管内皮细胞的增殖和迁移。本研究旨在探讨 c-Myc 在胶质瘤发生发展中的生物学意义，我们下调了人胶质母细胞瘤细胞系 IN500 中 c-Myc 的表达，并研究了其对细胞生长、增殖和凋亡的体外影响以及在异种移植小鼠模型中对肿瘤形成的体内影响。
IN500Δ细胞用表达 shRNA 的质粒稳定转染 c-Myc（pCMYC-shRNA）或作为对照（pCtrl-shRNA）。建立稳定细胞后，通过逆转录（RT）-PCR 检测 c-Myc 和 VEGF 的 mRNA 表达，通过 Western blot 和免疫组化检测 c-Myc 和 VEGF 蛋白。通过流式细胞术测定细胞周期进程和细胞凋亡。通过将稳定细胞皮下注射入免疫缺陷裸鼠来确定靶向 c-Myc 的体内作用。
pCMYC-shRNA 的稳定转染成功敲低了 IN500 中 c-Myc 的稳定态 mRNA 和蛋白水平，与 VEGF 的下调呈正相关。体外下调 c-Myc 也导致 G1-S 期阻滞和增强的细胞凋亡。在体内，靶向 c-Myc 减少了异种移植肿瘤的形成，并导致肿瘤明显缩小。
c-Myc 在胶质母细胞瘤的发展中有多种功能，包括调节细胞周期、凋亡和 VEGF 表达。靶向 c-Myc 表达可能是治疗恶性神经胶质瘤的一种有前途的治疗方法。
