Objective: To isolate and clone the tumor suppressor gene on chromosomal region 7q32 correlated with the carcinogenesis of human nasopharyngeal carcinoma (NPC).
Methods: The genotypes of polymorphic microsatellite markers on 7q32 in DNA from 24 biopsies of nasopharyngeal carcinoma and matched normal blood cells were identified. The expression levels of 20 expressed sequence tags (ESTs) on 7q32 between human nasopharyngeal carcinoma epithelial 1 (HNE1) and primary cultures of normal nasopharyngeal epithelial (PNNE) cells were compared using differential RT-PCR and Northern hybridization. The quantity of AA070437 DNA and mRNA was detected by differential PCR and differential RT-PCR, respectively.
Results: Loss of heterozygosity (LOH) was found in 25%-46% of NPC biopsies. AA070437 EST expression was down-regulated in HNE1 cell compared to PNNE cells. The down-regulation of AA070437 was found in 30.7% of NPC biopsies and allelic loss of AA070437 was observed in 29.1% of NPC biopsies.
Conclusion: Our results show that AA070437 EST is negatively related with the occurrence of human NPC and may represent a candidate tumor suppressor gene of NPC on 7q32.