Abstract 2104: Frequent inactivation of A20 and its prognostic significance in Middle Eastern colorectal carcinoma

Proceedings: AACR 102nd Annual Meeting 2011‐‐ Apr 2‐6, 2011; Orlando, FL A20, also known as TNF alpha induced protein3 (TNFAIP3), is a tumor suppressor gene and a well-known negative regulator of the NF-kB pathway in hematolymphoid neoplasms. In colorectal carcinoma (CRC), aberrant NF-kB regulation has been associated with poor prognosis and resistance to therapy. However, role of A20 gene in CRC is unknown. Therefore, we sought to elucidate the biological role of A20, mechanism of its inactivation and its prognostic role in colorectal carcinoma. We investigated the genetic and epigenetic abnormalities of A20 gene in CRC. In a tissue microarray cohort of 434 CRC, we studied loss of A20 protein expression by immunohistochemistry and A20 deletions by FISH. We also screened 116 random CRC and 14 CRC cell lines for mutations in A20 gene and A20 promoter methylation. Of the 116 CRC samples, A20 deletions were seen in 15.3% and incidence of A20 mutation was 2.5%; most of the mutations (4/5) were missense mutations. A20 promoter hyper-methylation was seen in 50.8% and was correlated with loss of protein expression (p=0.0079). A20 inactivation, defined as loss or reduced expression of protein was observed in 63% of CRC and A20 inactivation was an independent prognostic marker for poor survival in all CRC. In addition A20 expression retained its prognostic value in the following subgroups: Stage III; Stage II and III; and Stage III and IV. A20 was inactivated in majority of the CRC due to promoter methylation and can be targeted to modulate NF-κb expression. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2104. doi:10.1158/1538-7445.AM2011-2104