[Relationship of bcl-2 gene expression with cell proliferation and apoptosis in human gliomas]

To investigate the relationship of bcl-2 gene expression level in human gliomas with the malignant degree, cell proliferative activity and apoptosis of the tumors.

The expression of bcl-2 mRNA, bcl-2 protein and proliferating cell antigen, and the apoptosis in sixty-nine human glioma specimens with different malignant grades were studied using in situ hybridization, in situ cell death detection (TUNEL method) and immunohistochemistry.

Of the 69 gliomas, 64 (92.8%) and 60 (87.0%) expressed bcl-2 mRNA and bcl-2 protein, respectively. The expression levels of bcl-2 mRNA and bcl-2 protein were correlated positively with each other (r(s) = 0.999, P < 0.01). The expression levels of bcl-2 mRNA and bcl-2 protein were both higher in WHO grade IV gliomas than in grade III gliomas, and the expression was lowest in grade I-II gliomas (P < 0.02 approximately 0.001). With the increase in the expression of bcl-2 protein, the cell proliferating activity increased and apoptosis decreased in the tumor cells. There was significant difference of cell proliferation and apoptosis between + + + group and + + group of bcl-2 protein expression (P < 0.05) as well as between both the former groups, and the negative and + group (P < 0.01) respectively.

Over-expression of bcl-2 gene inhibits apoptosis of glioma cells, and the inhibitory intensity increases with the ascending of bcl-2 gene expression level in glioma cells. Both the decrease in apoptosis caused by bcl-2 gene over-expression and the excessive cell proliferation promoted by other gene abnormalities may result in unlimited cell accumulation, which may play an important role in the development and malignant progression of gliomas.