PT - JOURNAL ARTICLE AU - Lo, Kwok-Wai AU - Kwong, Joseph AU - Hui, Angela Bik-Yu AU - Chan, Sylvia Yat-Yee AU - To, Ka-Fai AU - Chan, Andrew Siu-Chung AU - Chow, Lillian Shuk-Nga AU - Teo, Peter M. L. AU - Johnson, Philip J. AU - Huang, Dolly Poon TI - High Frequency of Promoter Hypermethylation of <strong><em>RASSF1A</em></strong> in Nasopharyngeal Carcinoma DP - 2001 May 15 TA - Cancer Research PG - 3877--3881 VI - 61 IP - 10 4099 - http://cancerres.aacrjournals.org/content/61/10/3877.short 4100 - http://cancerres.aacrjournals.org/content/61/10/3877.full SO - Cancer Res2001 May 15; 61 AB - We have investigated the genetic and epigenetic changes of a newly isolated tumor suppressor gene on 3p21.3, RASSF1A, in nasopharyngeal carcinoma (NPC). Four xenografts, four cell lines and 21 primary tumors were examined. Promoter hypermethylation of the 5′CpG island of RASSF1A was detected in 4 of 4 (100%) xenografts, in 3 of 4 (75%) cell lines, and in 14 of 21 (66.7%) primary tumors but not in the normal nasopharyngeal epithelia. Mutations were found in 2 of 21 (9.5%) primary tumors. In the cell lines and xenografts with extensive methylation, no RASSF1A gene expression was found. After treatment with 5′-aza-2′deoxycytidine, reexpression and demethylation of the RASSF1A gene were detected in a NPC cell line. These findings suggest that promoter hypermethylation may participate in the transcriptional inactivation of the RASSF1A gene in NPC. The high incidence of RASSF1A alterations suggest that it is the critical target gene on chromosome 3p21.3 involved in the development of NPC. ©2001 American Association for Cancer Research.