Inactivation of LLC1 gene in nonsmall cell lung cancer

✍ Scribed by Kyeong-Man Hong; Sei-Hoon Yang; Sinchita Roy Chowdhuri; Audrey Player; Megan Hames; Junya Fukuoka; Daoud Meerzaman; Tatiana Dracheva; Zhifu Sun; Ping Yang; Jin Jen

• Publisher: John Wiley and Sons
• Year: 2007
• Tongue: French
• Weight: 448 KB
• Volume: 120
• Category: Article
• ISSN: 0020-7136
• DOI: 10.1002/ijc.22577

✦ Synopsis

Abstract

Serial analysis of gene expression studies led us to identify a previously unknown gene, c20orf85, that is present in the normal lung epithelium but absent or downregulated in most primary nonsmall cell lung cancers and lung cancer cell lines. We named this gene LLC1 for __L__ow in __L__ung __C__ancer 1. LLC1 is located on chromosome 20q13.3 and has a 70% GC content in the promoter region. It has 4 exons and encodes a protein containing 137 amino acids. By in situ hybridization, we observed that LLC1 message is localized in normal lung bronchial epithelial cells but absent in 13 of 14 lung adenocarcinoma and 9 out of 10 lung squamous carcinoma samples. Methylation at CpG sites of the LLC1 promoter was frequently observed in lung cancer cell lines and in a fraction of primary lung cancer tissues. Treatment with 5‐aza deoxycytidine resulted in a reduced methylation of the LLC1 promoter concomitant with the increase of LLC1 expression. These results suggest that inactivation of LLC1 by means of promoter methylation is a frequent event in nonsmall cell lung cancer and may play a role in lung tumorigenesis. © 2007 Wiley‐Liss, Inc.