GENOMIC ALTERATIONS IN NASOPHARYNGEAL CARCINOMA - LOSS OF HETEROZYGOSITY AND EPSTEIN-BARR-VIRUS INFECTION

Nasopharyngeal carcinoma is a subset of head and neck squamous cell ca ncers with unique endemic distribution and aetiological co-factors. Ep stein-Barr virus has been revealed to be an important aetiological fac tor for most nasopharyngeal carcinomas. Nevertheless, additional genet ic alterations may be involved in their development and progression. T he aim of this study was to determine the likely chromosomal locations of tumour-suppressor genes related to Epstein-Barr virus-associated n asopharyngeal carcinoma. Fifty-six microsatellite polymorphic markers located on every autosomal arm were used to estimate the incidence of loss of heterozygosity in 27 Epstein-Barr virus-associated nasopharyng eal carcinomas. High frequencies of allelic loss were observed on chro mosome 3p (75.0%) and 9p (87.0%). Chromosome 9q, 11q, 13q and 14q disp layed loss in over 50%, while chromosome 3q, 6p, 16q, 19q and 22q exhi bited loss in 35-50%. Furthermore, several other chromosomal arms demo nstrated allelic loss in 20-35% Additionally, 1 of the 27 cases showed microsatellite instability at multiple loci. These findings provide e vidence of multiple genetic alterations during cancer development and clues for further studies of tumour-suppressor genes in Epstein-Barr v irus-associated nasopharyngeal carcinoma.