Physical and transcript map of the minimally deleted region III on 17p implicated in the early development of Barrett's oesophageal adenocarcinoma

Abstract

Allelic imbalance (AI) studies on chromosome 17 (C17) in Barrett's oesophageal adenocarcinoma (BOA) tumours strongly suggest that a minimally deleted region on C17p harbours a BOA-associated gene with tumour suppressor function. This deleted region, designated minimal region III (MRIII), lies between the two microsatellite markers D17S1852 and D17S954. Computational sequence analysis techniques, BLAST and NIX, were used to assemble a physical map of MRIII, consisting of three overlapping bacterial artificial chromosome (BAC) clones, 297N7, 963H4 and 795F17, from the RPCI-11 library. The 270 kb genomic sequence of MRIII was analysed using the computational gene prediction methods NIX and TAP to identify putative BOA genes. A transcript map of MRIII has been generated and contains 25 candidate BOA genes, four of which are the named genes MYH3, SCO1, x006 and MAGOH-LIKE. The other candidates consist of seven genes predicted by TAP with associated ESTs identified by NIX, two genes predicted by TAP alone and 12 genes/ESTs (or pairs of ESTs) identified by NIX alone. No disease-specific mutations were identified in x006 or MAGOH-LIKE, although expression analysis of these genes suggests that they may show alternative splicing or be altered epigenetically or in regulatory regions in oesophageal cancer.

Methylation of SOCS-3 and SOCS-1 in the carcinogenesis of Barrett's adenocarcinoma

“…1 2 To date, the exact cellular and molecular mechanisms leading to neoplastic progression in Barrett's epithelium are still not fully understood. [3][4][5] However, the initial step in the carcinogenic process is thought to be an intermediate step in the progression from reflux oesophagitis to oesophageal adenocarcinoma.…”

Mutations of BRAF and KRAS2 in the development of Barrett's adenocarcinoma

“…To date, the exact cellular and molecular mechanisms leading to neoplastic progression in Barrett's epithelium are still not fully understood (Barrett et al, 1999;Dunn et al, 2003). Increasing evidence exists that carcinogenesis must be understood in terms of an accumulation of mutations in regulatory genes, including activation of oncogenes and inactivation or loss of the tumoursuppressor genes (Morales et al, 2002).…”

Molecular Findings in Barrett’s Epithelium

“…LOH of 17p (chromosomal location of p53) identifies a patient subset at increased risk for neoplastic progression [33,38]. On the other hand, LOH on chromosomes 9p and 17p have been found frequently in Barrett's metaplasia not associated with dysplasia or adenocarcinoma [39,40].…”