Frequent Allelic Loss and Reduced mRNA Expression of ING4, A Novel Candidate Tumor Suppressor Gene, in Head and Neck Cancer

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We previously showed two members of the ING family, ING1 and ING3 as a tumor suppressor gene in head and neck cancer. A novel member of ING family, ING4 localized to chromosome 12p13.31 region was cloned. ING4 harbors the PHD domain highly homologous among ING family proteins. Loss of heterozygosity analysis was performed at 12p12-13 region in 50 head and neck squamous cell carcinomas by using six highly polymorphic microsatellite markers and 33 out of the 50 cases (66%) showed allelic loss. Although somatic mutation of the ING4 gene was not found in head and neck cancers, quantitative real-time RT-PCR analysis demonstrated decreased expression of ING4 mRNA in 76% of primary tumors as compared with that of matched normal samples. Frequent deletion and decreased mRNA expression of ING4 suggested it as a class II tumor suppressor gene and may play an important role in head and neck cancer.