Promoter hypermethylation-mediated down-regulation of RUNX3 gene in human brain tumors.

BACKGROUND: The Runx family proteins, including RUNX3, are tissue-restricted transcription factors and play role in neuronal development and tumorigenesis. RUNX3 has an important role in glioblastoma (GBM) tumorigenesis because of its promoter hypermethylation. AIM: We aimed to evaluate the methylation-mediated expression regulation of RUNX3 gene in brain tumors. PATIENTS AND METHODS: Cases of meningiomas WHO grade III (3), anaplastic astrocytomas (3), diffuse astrocytoma (3), and GBM (12) were recruited into this study. Real-time quantitative PCR was performed for analyses of DNA promoter methylation and analyses of methylation-mediated expression status of RUNX3 gene was performed by real-time quantitative RT-PCR. RESULTS: There was no significant difference between methylated and unmethylated quantitative ratio of RUNX3 gene promoter region and also no significant difference in relative ratio of RUNX3 gene expression in brain tumor groups. Methylated and unmethylated ratio in anaplastic astrocytoma, diffuse astrocytoma, GBM, meningioma (WHO grade III) and in all groups were; 1.44, 1.09, 1.51, 1.52 and 1.43, respectively. One allele was found methylated necessarily. No methylation was detected in one case of GBM group and one case of anaplastic astrocytoma group. There was no unmethylated promoter in one of the GBM cases. There were significant differences between relative ratio of RUNX3 gene expression and methylated/unmethylated ratio rates for all cases (p = 0.001) and GBM groups (p = 0.041). CONCLUSION: This study overemphasized the RUNX3 gene importance in brain tumors, due to the existence of at least one methylated allele.

Incidence of fibroblast growth factor receptor 3 gene (FGFR3) A248C, S249C, G372C, and T375C mutations in bladder cancer.

Bladder cancer is the most frequent cancer of the urinary system. Fibroblast growth factor receptors (FGFR) belong to the tyrosine kinase family and have important roles in cell differentiation and proliferation and embryogenesis. FGFR3 is located on chromosome 4p16.3, and missense mutations of FGFR3 are associated with autosomal dominant human skeletal disorders and have some oncogenic effects. We examined the incidence of FGFR3 thanatophoric dysplasia mutations located in exon 7, A248C and S249C, and in exon 10, G372C and T375C, and their correlation with clinical-pathological parameters in bladder carcinoma patients. Fifty-six paraffin-embedded specimens of transitional cell carcinoma of the urinary bladder were included in this study. Analysis of FGFR3 thanatophoric dysplasia mutations located in exon 7, A248C and S249C, and in exon 10, G372C and T375C, was performed by PCR-restriction fragment length polymorphism (RFLP) analysis and DNA sequencing. FGFR3 thanatophoric dysplasia mutations located in exon 7, A248C and S249C, and in exon 10, G372C and T375C, were detected in 33 of the 56 patients (heterozygous mutant). Among the 56 transitional cell carcinomas, missense point mutations were detected in seven of them at codon A248C, 28 of them at codon S249C, and three of them at codon T375C, similar to data from previous reports. When the results of the FGFR3 thanatophoric dysplasia mutations located in exon 7, A248C and S249C and in exon 10, G372C and T375C, were analyzed one by one or as a group, despite the findings of previous research reports, our data suggest that these mutations are detected homogenously regardless of the tumor classification and tumor grade.

RNA interference-mediated URG4 gene silencing diminishes cyclin D1 mRNA expression in HepG2 cells.

Up-regulated gene 4 (URG4), stimulated by HBxAg, is a novel gene located on chromosome 7 (7p13). The full-length URG4 clone is 3.607 kb and encodes a polypeptide of 922 amino acids, with a molecular weight of 104 kDa (GeneID: 55665). It promotes cell growth, growth factor-independent survival, and anchorage-independent growth in HepG2 cells, and it accelerates tumor formation in nude mice. Hence, URG4 may be a natural effector of HBxAg and a putative oncogene that contributes to multi-step hepatocarcinogenesis. Cyclin D1 is frequently over-expressed in hepatocellular carcinoma, exhibiting a number of malignant phenotypes. We found that down-regulation of URG4 through RNA interference-mediated silencing suppressed cell proliferation in HepG2 cells. Over-expression of URG4 up-regulated cyclin D1 mRNA expression, whereas RNA interference-mediated URG4 silencing diminished cyclin D1 mRNA expression in HepG2 cells. The data suggest that URG4 may play an important role in the development of hepatocellular carcinoma by partially regulating the expression of cyclin D1 and has potential for use as a therapeutic target for hepatocellular carcinoma.