[Fine mapping of the loss of heterozygosity for chromosome 1pter-p36.11 in nasopharyngeal carcinoma].

OBJECTIVE: To construct a detailed mapping of the Chromosome 1pter-p36.11 deleted region (63.4 cM) in nasopharyngeal carcinoma (NPC) by polymerase chain reaction-loss of heterozygosity (PCR-LOH) analysis for the further research of NPC-related gene(s). METHODS: Biopsies from 47 cases of NPC patients were studied. DNA extracted from separated cancer cells and their corresponding non-cancer lymphocytes were amplified with PCR, followed by the analysis of LOH and microsatellite instability (MI) for 20 loci spanning Chromosome 1pter-p36.11 region with an average interval of 3.0 cM. RESULTS: 82.2% of NPC cases (37/47) showed at least one loci of LOH. The highest frequency of LOH was found at loci D1S234 on 1p36.13 (50.0%), with the LOH at loci D1S2644 on 1p36.22 slightly less (37.5%). The occurrence of LOH at D1S234 showed no significant difference for the cases at early stage and at advanced stage [60% (9/15) vs 50.0% (8/16) respectively, P > 0.05]. High frequencies of MI were detected at D1S243 on 1p36.33 (37.5%) and D1S199 on 1p36.21 (30.2%). CONCLUSIONS: There are two common deletion regions: one localized at 1p36.13 (D1S234, 2.0 cM) and the other at 1p36.22 (D1S436-D1S2644, 6.3 cM), with a MI loci at D1S199 between them. This suggests that one or more putative tumor suppressor gene(s) related to the early stage of NPC tumorigenesis may be encompassed in this zone.