ING1 and p53 tumor suppressor gene alterations in adenocarcinomas of the esophagogastric junction Yasuo Hara a , Zuoyu Zheng b,c , Susan C. Evans c , Dickran Malatjalian c , D. Christie Riddell c , Duane L. Guernsey c , Li Dong Wang b , Karl Riabowol a , Alan G. Casson c,d, * a Departments of Biochemistry, Molecular Biology and Oncology, University of Calgary, Calgary, Alberta T2N 1N2, Canada b Laboratory for Cancer Research, Henan Medical University, Zhengzhou, Henan 450052, China c Department of Pathology, Dalhousie University, Halifax, NS B3H 2Y9, Canada d Department of Surgery, Dalhousie University, Halifax, NS B3H 2Y9, Canada Received 26 June 2002; received in revised form 30 October 2002; accepted 5 November 2002 Abstract The aim of this study was to characterize molecular alterations of the recently reported candidate tumor suppressor gene, ING1, and to explore the relationship between ING1 and p53 in a well-defined series of adenocarcinomas of the esophagogastric junction (AdEGJ). Polymerase chain reaction (PCR)-based assays were used to characterize ING1 and p53 alterations, relative to histologically normal esophageal mucosa. Two tumors were found to have ING1 mutations: one novel missense mutation (AGC Ser ! ATC Ile ) at codon 147, and one silent mutation (TCG Ser ! TCA Ser ) at codon 173. Reduced expression of the two major alternatively spliced ING1 messenger RNA variants, p47 ING1a and p33 ING1b was variable, but was reduced (1.2 – 10-fold) in 12 of 19 AdEGJs compared to normal esophageal epithelium. No association between p53 and ING1 alterations was apparent. We conclude that reduced ING1 expression is frequently associated with AdEGJ tumorigenesis, further supporting its role as a tumor suppressor gene, and that ING1 expression is independent of p53 status. q 2002 Elsevier Science Ireland Ltd. All rights reserved. Keywords: Adenocarcinoma; Esopgagogastric junction; ING1; p53; Tumor suppressor gene 1. Introduction Tumor suppressor genes play important roles in the regulation of cell growth and differentiation. The candidate tumor suppressor gene ING1 was recently cloned using a method that combined PCR-mediated subtractive hybridization of complementary DNAs (cDNAs) from normal and cancer cells, followed by an in vivo selection assay [1]. ING1 was localized to chromosome 13q34 [2,3], with a predicted 33 kD protein (p33 ING1b ). The gene was subsequently shown to be comprised of four exons (1a, 1b, 1c and 2), encoding four messenger RNA (mRNA) variants from three different promoter regions: p33 ING1b , p47 ING1a , p24 ING1c , and p27 ING1d [3,4]. Blocking ING1 expression promotes focus formation and cell pro- liferation in vitro [1], promotes tumor formation in vivo, and the p33 ING1b isoform cooperates with p53 in growth regulation, by modulating the activity of p53 0304-3835/02/$ - see front matter q 2002 Elsevier Science Ireland Ltd. All rights reserved. doi:10.1016/ S0304-3835(02)00635-3 Cancer Letters 192 (2003) 109–116 www.elsevier.com/locate/canlet * Corresponding author. Division of Thoracic Surgery, QEII Health Sciences Centre, Victoria Building 7S-013, 1278 Tower Road, Halifax, NS B3H 2Y9, Canada. Tel.: þ 1-902-473-2281; fax: þ 1-902-473-4426. E-mail address: alan.casson@dal.ca (A.G. Casson).