Sirt1 antisense transcript is down-regulated in human tumors.

Natural antisense transcripts (NATs) have recently been associated with the development of human cancers. Recent studies have shown that a natural antisense transcript (NAT) is present in Sirt1 gene which encodes a NAD-dependent deacetylase. Interestingly, expression of Sirt1 mRNA changes during development and progression of human cancers. However, it remains unclear to what extent Sirt1 antisense transcript (AS) may contribute to changes in the expression of Sirt1 mRNA. To determine this, we used quantitative measurement of RNA to reveal relationship between Sirt1 mRNA and Sirt1-AS across human cancer tissues, cell lines and stem cells. While Sirt1 mRNA level was increased in cancer cell lines and cancer tissues, the expression level of Sirt1-AS was lower in cancers compared to controls. This inverse correlation was observed in the expression of Sirt1 sense and antisense transcripts in normal and cancer tissues suggesting a functional role for Sirt1-AS in regulation of Sirt1 mRNA.