Genome Wide Loss of Heterozygosity in Primary Nasopharyngeal Carcinoma

Objectives: To analyze the genome wide loss of heterozygosity (LOH) and to localize the high frequent LOH regions in nasopharyngeal carcinoma (NPC), in order to provide molecular genetic evidence for localizing NPC related tumor genes. Methods: The PCR based microsatellite polymorphism analysis technique was performed on 98 cases of sporadic primary NPC by using a large panel of 335 polymorphism markers. Results: In the 22 chromosomes, at least one locus showed LOH frequency more than 30% on 19 chromosomes, and there was no locus showed LOH frequency more than 30% on three chromosomes (chromosomes 15, 20 and 22). Of the 335 informative markers, 4 loci showed LOH frequency ≥60%, 3 of them are located on chromosome 3 and 1 is located on chromosome 9; 5 loci showed LOH frequency from 50% to 59%, three of them are located on chromosome 3, and 1 on chromosome 5 and 11; 22 loci showed LOH frequency from 40% to 49%, and 52 loci showed LOH frequency from 30% to 39%; the other 252 loci showed LOH frequency less than 30% indicated that of background losses in NPC. The high frequent LOH loci (more than 30%) were clustered to 12 chromosomal arms which distributed to 1p36 34, 3p24 26, 3p14 21, 3q25 27, 4q35 31, 5q15 21 and 5q32 33, 8p22 23, 9p21 23 and 9q33 34, 11p12 14, 11q13 23, 13q13 14 and 13q31 32, 14q11 13, 14q23 24, 14q32. Moreover, the authors also firstly reported high frequent LOH on chromosome 1p, 5q and 19q, and the LOH deletion map indicated that there may be NPC related tumor suppressor genes located at these deleted regions. Conclusions: Our results indicate that high frequent LOH occurred on multiple chromosomal arms in NPC were common genetic events, and there may exist TSGs which play an important role in the development and progression of NPC in the deleted chromosomal regions.