周期蛋白依赖性激酶1在胶质瘤组织中的表达及其沉默对胶质瘤细胞恶性表型的影响

目的探讨周期蛋白依赖性激酶1(CDK1)在胶质瘤组织中的表达及其沉默对胶质瘤细胞恶性表型的影响。方法利用自建的人脑胶质瘤体外细胞系SHG44及其移植瘤组织、脑肿瘤干细胞、神经干细胞、不同恶性程度的胶质瘤手术标本构建组织芯片,免疫组化染色检测其CDK1蛋白表达;应用RNA干扰技术使CDK1在SHG44细胞及其移植瘤组织中沉默,观察其随后发生的表型变化。结果CDK1在临床标本中随胶质瘤恶性程度升高表达强度增加,Ⅰ-Ⅳ级的阳性表达率分别为22.2%、40.0%、69.6%和78.6%(P=0.01)。体外培养的人脑胶质瘤SHG44细胞球体和裸小鼠皮下移植瘤CDK1表达强度均较高,而神经干细胞和脑肿瘤干细胞球体表达强度低,在细胞增殖活性高的人胚胎脑组织和裸小鼠骨髓中CDK1亦高表达,但在正常成人脑组织低表达。C1和C3体外转染SHG44细胞后,将细胞周期阻滞在G2/M期,而且诱导了凋亡,细胞凋亡率分别上升至27.8%和36.5%。CDK1沉默的裸鼠皮下移植瘤瘤重明显降低,细胞凋亡率为57.1%,明显高于对照组(8.5%)。结论CDK1的高表达呵促进胶质瘤的发生和发展,CDK1沉默后的肿瘤细胞恶性表型可得到控制,CDK1可作为胶质瘤病因分子行进一步研究。

CDK1 expression and effects of CDK1 silencing on the malignant phenotype of glioma cells

OBJECTIVE: Our previous cDNA array data have shown that expression level of CDK1 increased along with the malignant progression of ganglioglioma, and decreased with the differentiation process of neural stem cells. The purpose of this study was to investigate the CDK1 expression levels in gliomas and the effects of CDK1 knockdown on phenotype of glioma cells. METHODS: Glioma tissue array was constructed, which was composed of surgical specimens of gliomas with different malignancy grades, glioma xenografts in nude mice, cellular spheroids of brain tumor stem cells, normal neural stem cells and glioma cell line. CDK1 expression was detected in glioma tissue array with immunohistochemical techniques. CDK1 expression in human brain glioma cell line and relevant xenogeneic graft tumor was inhibited by retroviral vectors expressing short hairpin RNAs (shRNAs). Both in vitro and in vivo changes of biological characteristics were further observed. RESULTS: The expression level of CDK1 increased along with the malignancy progression of glioma in clinical specimens. The positive expression rates of CDK1 in human brain glioma tissues were 22.2% (grade I), 40.0% (grade II), 69.6% (grade III) and 78.6% (grade IV), P = 0.01, respectively. The positive expression rate of CDK1 in glioma cell line and implanted xenografts was similar as the clinical tumors with high malignancy, and higher than those in neural stem cells and brain tumor stem cells (P = 0.0014). Expression of CDK1 was high in human fetal brain tissues and bone marrows of nude mice, but low in normal adult human brain tissues. Downregulation of CDK1 inhibited the proliferation activities notably both in SHG-44 cells in vitro and relevant xenogeneic graft tumors, and induced apoptosis of tumor cells prominantly as well. CONCLUSION: Overexpression of CDK1 may promote oncogenesis and progression of human gliomas. Downregulation of CDK1 expression can inhibit the proliferation activities of human malignant gliomas.