Mutations and aberrant DNA methylation of the <i>PROX1</i> gene in hematologic malignancies

Abstract

The homeobox gene PROX1 is related to the Drosophila prospero gene, which is expressed in the developing central nervous system and lens-secreting cone cells. We found that the PROX1 gene had missense and nonsense mutations in 4 of 29 hematologic cell lines analyzed. Decreased mRNA expression was also observed in half of these cell lines by RT-PCR. The restoration of PROX1 gene expression after treatment with the demethylating agent 5-aza-2'-deoxycytidine, as well as bisulfite sequencing analysis, indicated that gene silencing is caused by DNA hypermethylation at intron 1. Such hypermethylation was also seen in primary lymphomas (56.3%, 18/32) in a tumor-specific manner. These findings indicate that the profile of the PROX1 gene corresponds to that of a candidate tumor-suppressor gene.