Aberrant hypermethylation of the FGFR2 gene in human gastric cancer cell lines.

Department of Biochemistry and BK21 Center for Advanced Medical Education, Inha University School of Medicine, Incheon 400-712, Republic of Korea.
Biochemical and Biophysical Research Communications (Impact Factor: 2.41). 07/2007; 357(4):1011-5. DOI:10.1016/j.bbrc.2007.04.051
Source: PubMed

ABSTRACT We have previously shown that fibroblast growth factor receptor 2 (FGFR2) plays an important role in gastric carcinogenesis. In this study, we assessed DNA methylation status in the promoter region of FGFR2 gene in gastric cancer cell lines, and indicated that this region was highly methylated, compared with FGFR2-expressing gastric cancer cell lines. Moreover, the restoration of FGFR2 expression by treating methylated cells with the DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine strongly suggests that the loss of FGFR2 expression may be due to the aberrant hypermethylation in the promoter region of the FGFR2 gene. Thus, our results suggest that the epigenetic silencing of FGFR2 through DNA methylation in gastric cancer may contribute to tumor progression.

0 0
  • [show abstract] [hide abstract]
    ABSTRACT: Homeobox C6 (HOXC6) genes belong to the homeoprotein family of transcription factors, which play an important role in morphogenesis and cellular differentiation during embryonic development. The aim of this study was to explore the role of HOXC6 in the regulation of Bcl-2 in human head and neck squamous cell carcinoma (HNSCC). The HOXC6 and Bcl-2 gene were identified as being overexpressed in HNSCC tissue and cell lines. Transfection assays demonstrated that HOXC6 increased the levels of Bcl-2 mRNA and protein. A luciferase reporter assay suggested that HOXC6 induced activity of the Bcl-2 promoter. A series of Bcl-2 promoter deletion mutants were examined and the minimal HOXC6-responsive region was identified to be in the TAAT motif (-420 bp) of the Bcl-2 promoter. Interestingly, the inhibition of HOXC6 using siRNA led to the repression of Bcl-2 expression and induced caspase-3-dependent apoptosis; overexpression of HOXC6 in HNSCC cells increased the resistance to paclitaxel-induced apoptosis. Together, our findings suggest that HOXC6 is an important mechanism of the anti-apoptotic pathway via regulation of Bcl-2 expression.
    Journal of Biological Chemistry 08/2012; 287(42):35678-88. · 4.65 Impact Factor
  • Source
    [show abstract] [hide abstract]
    ABSTRACT: To identify potential tumor suppressor genes, genome-wide data from exome and transcriptome sequencing were combined to search for genes with loss of heterozygosity and allele-specific expression. The analysis was conducted on the breast cancer cell line HCC1954, and a lymphoblast cell line from the same individual, HCC1954BL. By comparing exome sequences from the two cell lines, we identified loss of heterozygosity events at 403 genes in HCC1954 and at one gene in HCC1954BL. The combination of exome and transcriptome sequence data also revealed 86 and 50 genes with allele specific expression events in HCC1954 and HCC1954BL, which comprise 5.4% and 2.6% of genes surveyed, respectively. Many of these genes identified by loss of heterozygosity and allele-specific expression are known or putative tumor suppressor genes, such as BRCA1, MSH3 and SETX, which participate in DNA repair pathways. Our results demonstrate that the combined application of high throughput sequencing to exome and allele-specific transcriptome analysis can reveal genes with known tumor suppressor characteristics, and a shortlist of novel candidates for the study of tumor suppressor activities.
    Genome biology 11/2010; 11(11):R114. · 10.30 Impact Factor
  • Source
    [show abstract] [hide abstract]
    ABSTRACT: Fibroblast growth factor receptor 2 isoform b (FGFR2-IIIb) is highly expressed in hepatocytes and plays an important role in liver homeostasis and regeneration. Here, we analyzed the expression and function of FGFR2-IIIb in hepatocellular carcinoma (HCC). FGFR2-IIIb expression in HCC tissues and cell lines was lower than in primary human hepatocytes and nontumorous tissue. FGFR2-IIIb-negative HCCs showed a significantly higher Ki-67 labeling index, and loss of FGFR2-IIIb expression correlated significantly with vascular invasion and more advanced tumor stages. A decrease in FGFR-2IIIb expression in HCC cell lines was not related to promoter hypermethylation. However, PCR analysis indicated that chromosomal deletion at 10q accounted for the loss of FGFR2 expression in a subset of HCC cells. FGFR2-IIIb re-expression in stable transfected HCC cell lines induced a higher basal apoptosis rate and a significantly reduced proliferation and migratory potential in vitro. In nude mice, FGFR2-IIIb re-expressing HCC cells grew significantly slower, and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay revealed higher apoptosis rates. The antitumorigenic effects of FGFR2-IIIb expression in HCC cells were not affected by keratinocyte growth factor or an inhibitor of FGFR-phosphorylation, indicating that they are independent of tyrosine kinase activation. In conclusion, our data indicate that FGFR2-IIIb inhibits tumorigenicity of HCC cells. Identification of the molecular mechanisms promoting regeneration in normal tissue while suppressing malignancy may lead to novel therapeutic targets of this highly aggressive tumor.
    American Journal Of Pathology 03/2010; 176(3):1433-42. · 4.52 Impact Factor