Cell cycle-dependent transcriptional regulation of calmodulin-binding transcription activator 1 in neuroblastoma cells.

A deletion of the short arm on human chromosome 1 is a common genetic abnormality in neuroblastoma, which is a highly malignant tumor in young childhood. Recently, calmodulin-binding transcription activator 1 (CAMTA1) gene was identified at 1p36 and considered as a candidate tumor suppressor of neuroblastoma. In the present study, we demonstrate that the expression levels of CAMTA1 mRNA were high in N-type neuroblastoma cell lines but low in S-type neuroblastoma cell lines. This result suggested that CAMTA1 could associate with the differentiation of neuroblastoma cells. Moreover, we examined the relationship between the expression of CAMTA1 and cell cycle progression in N-type neuroblastoma SK-N-SH cells. During cell cycle synchronization, cell cycle phases were checked by flow cytometry and Western blot analysis of cell cycle-related proteins. Then, the expression of CAMTA1 mRNA was determined by RT-PCR in each phase of the cell cycle. CAMTA1 mRNA showed a cell cycle-dependent expression, resulting in high levels of expression in S and M phases. Moreover, microscopic analysis revealed that the cell cycle-dependent expression of CAMTA1 protein is in agreement with mRNA expression. Taken together, CAMTA1 is expressed in S and M phases and decreased in post-mitosis. These results suggest that CAMTA1 may participate in induction of cell differentiation and cell cycle regulation.