ABSTRACT
BACKGROUND AND OBJECTIVES: Decreased expression and growth suppression of Tazarotene-Induced Gene 1 (TIG1) were reported in prostate cancer. In this study, we examined the possibility of TIG1 transcriptional silencing by hypermethylation in head and neck cancer. SUBJECTS AND METHOD: We extracted DNA and total RNA from five head and neck cell lines (O11, O12, O19, O22 and O28), and three prostate cell lines (PC3, LNCap and DU145). We checked the methylation status of TIG1 by methylation-specific PCR (MSP) and RT-PCR. We also examined primary cancer tissues of 32 head and neck cancer, 31 prostate cancer and 10 normal samples. RESULTS: We found that all of five head and neck (100%) cell lines and two of three prostate (66.7%) cell lines were methylated. RT-PCR analysis confirmed the absence of TIG1 expression in six cell lines with methylation. We checked primary cancer by MSP and found TIG1 methylation in 16 of 32 (50%) head and neck cancers, and 17 of 31 (54.8%) prostate cancers. Normal head and neck and prostate tissues were free of methylation. CONCLUSION: Our results support the notion that methylation might be an important mechanism of TIG1 inactivation and a target event in head and neck cancer.