Mapping of nasopharyngeal carcinoma tumor-suppressive activity to a 1.8-megabase region of chromosome band 11q13.

Nasopharyngeal carcinoma (NPC) is a malignancy that is particularly prevalent among populations from Southern China and Southeast Asian countries. Evidence for a genetic contribution to the disease has been documented, although the genetic basis for NPC development is not yet fully understood. Previous functional evidence of tumor-suppressive activity on chromosome band 11q13 in NPC was obtained using a microcell-mediated chromosome-transfer approach with HONE1 NPC cells. In the present study, this region was subjected to a detailed investigation of microcell hybrids and their tumor segregants using microsatellite analysis to narrow down the region of tumor-suppressive activity. Fluorescence in situ hybridization was also performed with BAC and cosmid probes to confirm the microsatellite data. The critical region responsible for tumor suppression was narrowed down to a 1.8-Mb interval, which does not tolerate an additional normal allele by chromosome transfer. One or two alleles from either endogenous or exogenous chromosomes at 11q13 were consistently eliminated during tumor growth. Results of this study suggest that a candidate tumor-suppressor gene, not the MEN1 gene, maps between D11S4907 and GSTP1 in NPC.