Mutation, Expression And DNA Methylation Of BUB1B Gene In Human Laryngeal Squamous Cell Carcinoma

ObjectiveTo explore the association of mutation, expression and DNA methylation ofBUB1B gene with tumorigenesis and progression of laryngeal squamous cellcarcinoma(LSCC).Material and MethodsLSCC tissues and paired normal tissues were taken during operation from 40patients without previous chemotherapy or radiotherapy. BUB1B gene mRNAexpression was evaluated by RT-PCR with (?)-actin as internal control. BUBR1 proteinexpression was evaluated by western blot with (?)-actin protein as internalcontrol.PCR-SSCP(PCR-single strand conformation polymorphism, PCR-SSCP) andDNA sequencing were used to detect mutation of BUB1B gene in 40 LSCC specimensand adjacent normal tissues. BUB1B gene promoter DNA methylation was detected bymethylation sensitive restriction endonuclease.Results40% (16/40 ) BUB1B mRNA expression level was lower than that of the pairednormal tissues (t=2．92, P<0．05) . The BUB1B to (?)-actin ratio of average density valuewas 0．863(?)0．178 in the cancer tissues, and 1．124(?)0．382 in the normal tissues. 35% (14/40) BUBR1 protein expression level was lower than that of the paired normal tissues(t=2．35, P<0．05) . In 16 low mRNA expression samples, 11 samples were accompaniedwith low protein expression(x=10．99, P <0．01) . However, PCR-SSCP analysis did notdetect any BUB1B gene mutation in 40 human LSCC and their adjacent normal tissues. BUB1B gene promoter DNA methylation was found in 12 out of 40 tumor samples(x =7．01, P <0．01) . The promoter DNA methylation of 9 samples was detected in 16 lowmRNA expression samples (x=14．34, P<0．01) . The promoter DNA methylation of 6samples was detected in 14 low BUBR1 expression samples (x=9．96, P <0．01) .ConclusionThese data suggested that mutation of BUB1B gene was rare in LSCC.Furthermore, there was a positive correlation between low gene expression and itspromoter region DNA methylation. This paper may implicate that BUB1B genepromoter region DNA methylation is responsible for the low gene expression and playsa role in tumorigenesis and progression of LSCC.