Background:
Neuronal synaptic junction protein delta-catenin (CTNND2) is often overexpressed in prostatic adenocarcinomas but the mechanisms of its activation are unknown. To address this question, we studied the hypothesis that Hes1, human homolog of Drosophila Hairy and enhancer of split (Hes) 1, is a transcriptional repressor of delta-catenin expression and plays an important role in molecular carcinogenesis.
Results:
We identified that, using a delta-catenin promoter reporter assay, Hes1, but not its inactive mutant, significantly repressed the upregulation of delta-catenin-luciferase activities induced by E2F1. Hes1 binds directly to the E-boxes on delta-catenin promoter and can reduce the expression of delta-catenin in prostate cancer cells. In prostate cancer CWR22-Rv1 and PC3 cell lines, which showed distinct delta-catenin overexpression, E2F1 and Hes1 expression pattern was altered. The suppression of Hes1 expression, either by gamma-secretase inhibitors or by siRNA against Hes1, increased delta-catenin expression. Gamma-secretase inhibition delayed S/G2-phase transition during cell cycle progression and induced cell shape changes to extend cellular processes in prostate cancer cells. In neuroendocrine prostate cancer mouse model derived allograft NE-10 tumors, delta-catenin showed an increased expression while Hes1 expression was diminished. Furthermore, E2F1 transcription was very high in subgroup of NE-10 tumors in which Hes1 still displayed residual expression, while its expression was only moderately increased in NE-10 tumors where Hes1 expression was completely suppressed.
Conclusion:
These studies support coordinated regulation of delta-catenin expression by both the activating transcription factor E2F1 and repressive transcription factor Hes1 in prostate cancer progression.

Read the original article at Molecular Cancer.