[Gene regulation during NGF--induced differentiation of neuroblastoma cells]

Neuroblastoma may arise from the blockage of differentiation of neuroblast along the neuronal pathway. In previous studies, we were able to induce differentiation of certain neuroblastoma cell lines with NGF. In order to study the gene regulation during differentiation, we hybridized several cDNA probes with RNA extracted from different cell lines before and after NGF treatment, and found that c-myc oncogene was down-regulated in NGF-induced differentiated cells in comparison with the control samples. The time course of c-myc down-regulation was concordant with the appearance of morphological changes of differentiation. No significant change was found in the expression of other oncogenes like K-ras and N-ras in the neuroblastoma cell lines before and after NGF treatment. The results indicate that down-regulation of c-myc oncogene may be one of the important events during NGF-induced differentiation and over expression of c-myc oncogene may, at least partly, be responsible for the development of neuroblastoma.