ART1 induces aberrant methylation of uPA promoter: a preliminary study

Colorectal carcinoma remains one of the most prevalent cancers with high morbidity and mortality. Arginine ADP-ribosyltransferase 1 (ART1) is one of the major mono-ADP-ribose transferases and has been shown to be involved importantly in many biological processes. DNA methylation is an important epigenetic mechanism in tumorgenesis. However, the influence of ART1 on DNA methylation contributing to this function in colorectal carcinoma cells remains unclear. The expression and activity of DNA methyltransferase 1 (DNMT1) was detected by western blotting. The binding between ART1 and DNMT1 was assessed by co-immunoprecipitation. The methylation status of uPA gene was determined by bisulfite sequencing PCR. DNMT1 expression and activity were increased as ART1 was silenced, and decreased as ART1 was over-expressed in CT26 colorectal carcinoma cells. The expression of DNMT1 decreased and uPA increased, respectively, following the treatment with 5-aza-2'deoxycytidine in GFP-shART1 group. Invasion and metastasis were enhanced in GFP-shART1 group treated with 5-aza-dC. Similar regulation of expression of DNMT1 and uPA were confirmed in Balb/c mice. This study revealed that silencing of ART1 induced hypermethylation of uPA gene and over-expression causes hypomethylation. It probably relates to the feedback mechanism of NF-kappa B to PARP1 thus mediating the expression and activity of DNMT1. The relationship between ART1 and DNA methylation might offer a new therapeutic target for the improved treatment of this major cancer.