| 1: Background and objectiveGliomas are the most frequent tumors in central nervous system, and their formation and development are multiple-factor and multiple-stage processes, which are related to the changes of many genes including the activation of oncogenes and deactivation of anti-oncogenes. Presently dozens of genes related to the formation and development of gliomas have been investigated, but they all locate upstream and the key genes are still unknown. CDC2 genes is found to be related to the tumorigenesis and malignant progression of gliomas by gene microarray in the studies of differentiation and dedifferentiation of glioma, and CyclinB1 is the key moderator to CDC2. The objective of this research is to prove whether CDC2 could be regarded as an etio-molecular of gliomas at the level of protein expression.2:MethodsTo design tissue microarrays containing 118 specimens, including clinical glioma tissues, cell lines spheres cultivated in vitro and their implanted xenograft tumor tissues of nude mice, brain tumor stem cells, neural stem cells and corresponding tissues for control. A tissue microarray instrument was used to prepare these tissue microarray paraffin blocks, which were made into slices and stained by immunohistochemistry for CDC2 and CyclinB1subsequently.3: ResultsTwo identical tissue microarray pareffin blocks containing 118 specimens with 1.5mm pore diameters were successfully made. Five points shifted, but none dropped. The results of HE staining showed concordance with the original pathologic diagnosis. And CDC2/CyclinB1 are located in cell nucleus. The positive expression rate of CDC2 in 71 cases of human brain glioma tissues was 54.9%, and the difference was significant statistically (P<0.05) when compared with normal adult brain tissues (18.2%). The positive expression rates of CDC2 in all grades of human brain glioma tissues were 22.2% (gradeâ… ), 40.0% (gradeâ…¡), 69.6% (gradeâ…¢) and 78.6% (gradeâ…£), respectively. And the differences between the contiguous grades were statistically significant (P < 0.01). Furthermore, the positive expression rates of CDC2 were positively correlated with the pathologic grades (rs=0.982,t=7.426,P<0.05). The positive expression rate of CDC2 in SHG44 cells and GBM cells was higher than that in neural stem cells and brain tumor stem cells (P=0.0014). The positive expression rate of Cyclin B1 in 71 cases of human brain glioma tissues was 52.1%; However, the positive expression rate of Cyclin B1 in 11 normal adult brain tissues was 9.0%; and there were statistically significant differences between cases and controls (P<0.05). And the differences between all grades were also significant (P<0.05); Furthermore, the pathological grades were positively correlated with the positive expression rates of Cyclin B1 (r=0.959, P=0.041). The high expressions were observed in glioma cellular spheroids cultured in vitro, subcutaneous implanted xenografts of nude mice, human fetal brain tissues and bone marrows of nude mice; but non-expressions in spheroids of brain tumor stem cells and neural stem cells. The co-expression rate of CDC2 and Cyclin B1 was 89.7%.The expressions of CDC2 and Cyclin B1 were positively correlated (r=0.90,P<0.01).4:ConclusionThe co-expression of CDC2 and Cyclin B1 increased with the malignant progression in brain gliomas, and they can promote glioma development. Their low-expression in nueral stem cells and brain stem cells, both of which basically stay in G0 stage, but high-expression in these actively proliferative cells such as SHG-44 cell line and GBM cellular spheres, indicate their roles in inhibiting the differentiation in tumor cells. CDC2 is worthy of the further studies for the molecular etiology of gliomas no matter at the level of mRNA or protein. |
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