RESUMEN
The strong associations between oral squamous cell carcinoma (OSCC) and dietary habits such as alcohol consumption (A), betel quid chewing (B) and cigarette smoking (C) and its predominance in men have been well documented; however, systemic analysis of OSCC is limited. Our study applied high-throughput screening methods to identify causative epigenetic targets in a cohort of men with ABC-associated OSCC. We identified BEX1 and LDOC1 as two epigenetically silenced X-linked tumour suppressors and demonstrated a functional link between the transcription of BEX1 and LDOC1 and promoter hypermethylation. Methylation of the BEX1 and LDOC1 promoters was associated significantly (p < 0.0001) with OSCC and were detected in 75% (42/56) and 89% (50/56) of the samples, respectively. We observed concordant increases in the methylation of both genes in 71% (40/56) of the tumours, and potent in vitro and in vivo growth inhibitory effects in OSCC cells ectopically expressing BEX1 and/or LDOC1. Restored expression of BEX1 and LDOC1 suppressed the nuclear factor-κB (NF-κB) signalling pathway, which is the most frequently hyperactivated signalling pathway in OSCC. This suppression might result from decreased p50 and p65 expression. These findings suggest that silencing of BEX1 and LDOC1 by promoter hypermethylation might represent a critical event in the molecular pathogenesis of OSCC and account for the oncogenic effects of ABC exposure and the male predominance of OSCC occurrence. Microarray data are available in the Gene Expression Omnibus (GEO; http://www.ncbi.nlm.nih.gov/geo/)
Asunto(s)
Biomarcadores de Tumor/genética , Carcinoma de Células Escamosas/genética , Regulación Neoplásica de la Expresión Génica , Neoplasias de la Boca/genética , Proteínas del Tejido Nervioso/genética , Proteínas Nucleares/genética , Proteínas Supresoras de Tumor/genética , Animales , Biomarcadores de Tumor/metabolismo , Carcinoma de Células Escamosas/metabolismo , Carcinoma de Células Escamosas/patología , Línea Celular , Estudios de Cohortes , Metilación de ADN , Regulación hacia Abajo , Epigénesis Genética , Silenciador del Gen , Genes Ligados a X , Ensayos Analíticos de Alto Rendimiento , Humanos , Masculino , Ratones , Ratones SCID , Neoplasias de la Boca/metabolismo , Neoplasias de la Boca/patología , FN-kappa B/genética , FN-kappa B/metabolismo , Proteínas del Tejido Nervioso/metabolismo , Proteínas Nucleares/metabolismo , Análisis de Secuencia por Matrices de Oligonucleótidos , Regiones Promotoras Genéticas/genética , Distribución Aleatoria , Factores Sexuales , Transducción de Señal , Proteínas Supresoras de Tumor/metabolismoRESUMEN
BACKGROUND: The root of Boehmeria spp (ramie) is a hepatoprotective Chinese herbal medicine. Medicinal properties vary between Boehmeria nivea var. nivea and Boehmeria nivea var. tenacissima, which are local species found in Taiwan. As commercial preparations may use either species, there is a need for a rapid and simple assay to identify variants for quality control. METHODS: Four methods were developed and tested for their applicability in differentiating the two species. These methods were random amplified polymorphic DNA (RAPD); sequence characterized amplified regions (SCAR); single nucleotide polymorphisms (SNP) and cleaved amplified polymorphic sequences (CAPS). RESULTS: Three RAPD markers were developed that produced unique bands in B. nivea var. tenacissima and B. nivea var. nivea. Based on sequenced RAPD bands, one SCAR marker was developed that produced a single DNA band in B. nivea var. nivea. Two SNP markers differentiated between B. nivea var. nivea and B. nivea var. tenacissima based on single nucleotide substitutions. A pair of CAPS oligonucleotides was developed by amplifying a 0.55-kb DNA fragment that exhibited species-specific digestion patterns with restriction enzymes Alf III and Nde I. Consistent results were obtained with all the four markers on all tested Boehmeria lines. CONCLUSION: The present study demonstrates the use of the RAPD, SCAR, SNP and CAPS markers for rapid identification of two closely related Boehmeria species.