We previously demonstrated that loss of 13q occurred in greater than 50% of primary head and neck squamous cell carcinomas. Although the minimal region of loss at 13q14.1-14.3 included the Rb1 gene, Rb1 inactivation was found to be rare. To further investigate possible targets of 13q loss in head and neck cancer, 32 primary tumors were fine mapped by microsatellite analysis with the use of 10 new markers spanning the minimal region. Twenty- one (66%) of 32 tumors displayed loss of heterozygosity and once again the minimal region of loss was confirmed to be 13q14.1-14.3. In addition to 6 monosomies, 11 tumors had regions of loss that either selectively deleted (one tumor) or stretched into the BRCA2 region 13q12-13 (10 tumors). Therefore we pursued investigation of the BRCA2 gene by a coupled transcription and translation assay of its largest exon (exon 11; 4932 base pairs) to detect functional truncations indicative of mutation in 37 primary head and neck tumors with 13q loss. These tumors included 17 of the 32 tumors recently analyzed and 20 other tumors with 13q loss from a previous study. Additionally, we performed the transcription and translation assay on five head and neck cancer cell lines. We found no alterations in exon 11 of the BRCA2 gene in any of the tumors or cell lines suggesting that perhaps another tumor suppressor gene on 13q is involved in head and neck cancer.
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