Objective: To elucidate the relationship between bcl-2 gene expression and the frequency of apoptosis of tumor cells, and study the expression of p16 tumor suppressor gene in neuroblastoma.
Methods: In situ hybridization and immunohistochemistry methods were used to study the frequencies of expression of bcl-2 and p16 genes in 20 cases of neuroblastoma. Meanwhile, an in situ apoptotic cell detection method was adopted to detect the apoptotic cells in these tumors, and the number of apoptotic cells was compared with the bcl-2 gene expression in each case.
Results: In situ hybridization revealed that the positive frequencies of both bcl-2 and p16 gene expression in 20 neuroblastoma specimens were 95%, and the expression rates at the protein level of these 2 gene products as detected by immunohistochemistry were both 100%. There was no significant difference between the positive rates obtained by these 2 methods. Comparing the bcl-2 expression and apoptotic cell number in these specimens, we found that the apoptotic cell number increased as the level of bcl-2 expression decreased.
Conclusions: The bcl-2 gene was expressed in most of human neuroblastomas. The reverse correlation of bcl-2 expression and tumor cell apoptosis further confirms that bcl-2 as an important gene inhibiting cell apoptosis may indirectly promote the carcinogenesis of neuroblastoma. It seems that there was no significant loss of p16 gene expression in these cases.