Dopachrome tautomerase is a retinoblastoma-specific gene, and its proximal promoter is preferentially active in human retinoblastoma cells

Abstract

Purpose: Retinoblastoma (RB) is a malignant childhood intraocular tumor. Current treatment options for RB have undesirable side effects. A comprehensive understanding of gene expression in human RB is essential for the development of safe and effective new therapies. Methods: We reviewed published microarray and RNA sequencing studies in which gene expression profiles were compared between human RB and normal retina tissues. We investigated the expression of genes of interest using quantitative reverse transcription PCR. We examined the activities of cloned promoter DNA fragments with luciferase assay. Results: Dopachrome tautomerase (DCT) was among the most overexpressed genes in RB in published studies. We found that DCT was highly expressed in six of 13 samples microdissected from Thai RB tissues. Expression of DCT was absent or barely detected in retina tissues, various human ocular cells, and major organs. We also demonstrated that the −657 to +411 DCT promoter fragment efficiently directs RB cell–specific transcription of the luciferase reporter gene in cell lines. Conclusions: The present work highlights that DCT is one of the most RB-specific genes. The regulatory elements required for this cell-specific gene expression are likely located within its proximal promoter.