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Aberrant methylation and silencing of ARHI,an imprinted tumor suppressor gene in which the function is lost in breast cancers 总被引:6,自引:0,他引:6
Yuan J Luo RZ Fujii S Wang L Hu W Andreeff M Pan Y Kadota M Oshimura M Sahin AA Issa JP Bast RC Yu Y 《Cancer research》2003,63(14):4174-4180
ARHI is a maternally imprinted tumor suppressor gene that maps to a site on chromosome 1p31 where loss of heterozygosity has been observed in 40% of human breast and ovarian cancers. ARHI is expressed in normal ovarian and breast epithelial cells, but ARHI expression is lost in a majority of ovarian and breast cancers. Expression of ARHI from the paternal allele can be down-regulated by multiple mechanisms in addition to loss of heterozygosity. This article explores the role of DNA methylation in silencing ARHI expression. There are three CpG islands in the ARHI gene. CpG islands I and II are located in the promoter region, whereas CpG island III is located in the coding region. Consistent with imprinting, we have found that all three CpG islands were partially methylated in normal human breast epithelial cells. Additional confirmation of imprinting has been obtained by studying DNA methylation and ARHI expression in murine A9 cells that carry either the maternal or the paternal copy of human chromosome 1. All three CpG islands were methylated, and ARHI was not expressed in A9 cells that contained the maternal allele. Conversely, CpG islands were not methylated and ARHI was expressed in A9 cells that contained the paternal allele of human chromosome 1. Aberrant methylation was found in several breast cancer cell lines that exhibited decreased ARHI expression. Hypermethylation was detected in 67% (6 of 9) of breast cancer cell lines at CpG island I, 33% (3 of 9) at CpG island II, and 56% (5 of 9) at CpG island III. Hypomethylation was observed in 44% (4 of 9) of breast cancer cell lines at CpG island II. When methylation of CpG islands was studied in 20 surgical specimens, hypermethylation was not observed in CpG island I, but 3 of 20 cases exhibited hypermethylation in CpG island II (15%), and 4 of 20 cases had hypermethylation in CpG island III (20%). Treatment with 5-aza-2'-deoxycytidine, a methyltransferase inhibitor, could reverse aberrant hypermethylation of CpG island I, II and III and partially restore ARHI expression in some, but not all of the cell lines. Treatment with 5-aza-2'-deoxycytidine partially reactivated ARHI expression in cell lines with hypermethylation of CpG islands I and II but not in cell lines with partial methylation or hypomethylation of these CpG islands. To test the impact of CpG island methylation on ARHI promoter activity more directly, constructs were prepared with the ARHI promoter linked to a luciferase reporter and transfected into SKBr3 and human embryo kidney 293 cells. Methylation of the entire construct destroyed promoter activity. Selective methylation of CpG island II alone or in combination with CpG island I also abolished ARHI promoter activity. Methylation of CpG I alone partially inhibited promoter activity of ARHI. Thus, hypermethylation of CpG island II in the promoter region of ARHI is associated with the complete loss of ARHI expression in breast cancer cells. Other epigenetic modifications such as hypermethylation in CpG island III may also contribute to the loss of ARHI expression. 相似文献
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Hypermethylation and silencing of the putative tumor suppressor Tazarotene-induced gene 1 in human cancers 总被引:7,自引:0,他引:7
Youssef EM Chen XQ Higuchi E Kondo Y Garcia-Manero G Lotan R Issa JP 《Cancer research》2004,64(7):2411-2417
A variety of tumor suppressor genes are down-regulated by hypermethylation during carcinogenesis. Using methylated CpG amplification-representation difference analysis, we identified a DNA fragment corresponding to the Tazarotene-induced gene 1 (TIG1) promoter-associated CpG island as one of the genes hypermethylated in the leukemia cell line K562. Because TIG1 has been proposed to act as a tumor suppressor, we tested the hypothesis that cytosine methylation of the TIG1 promoter suppresses its expression and causes a loss of responsiveness to retinoic acid in some neoplastic cells. We examined TIG1 methylation and expression status in 53 human cancer cell lines and 74 primary tumors, including leukemia and head and neck, breast, colon, skin, brain, lung, and prostate cancer. Loss of TIG1 expression was strongly associated with TIG1 promoter hypermethylation (P < 0.001). There was no correlation between TIG1 promoter methylation and that of retinoid acid receptor beta2 (RARbeta2), another retinoic-induced putative tumor suppressor gene (P = 0.78). Treatment with the DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine for 5 days restored TIG1 expression in all eight silenced cell lines tested. TIG1 expression was also inducible by treatment with 1 micro M all-trans-retinoic acid for 3 days except in densely methylated cell lines. Treatment of the K562 leukemia cells with demethylating agent combined with all-trans-retinoic acid induced apoptosis. These findings indicate that silencing of TIG1 promoter by hypermethylation is common in human cancers and may contribute to the loss of retinoic acid responsiveness in some neoplastic cells. 相似文献
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Spreading of methylation within RUNX3 CpG island in gastric cancer 总被引:11,自引:0,他引:11
Homma N Tamura G Honda T Matsumoto Y Nishizuka S Kawata S Motoyama T 《Cancer science》2006,97(1):51-56
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Differential distribution of DNA methylation within the RASSF1A CpG island in breast cancer 总被引:12,自引:0,他引:12
Yan PS Shi H Rahmatpanah F Hsiau TH Hsiau AH Leu YW Liu JC Huang TH 《Cancer research》2003,63(19):6178-6186
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Hypermethylation of the TSLC1 gene promoter in primary gastric cancers and gastric cancer cell lines. 总被引:7,自引:0,他引:7
Teiichiro Honda Gen Tamura Takayoshi Waki Zhe Jin Kiyoshi Sato Teiichi Motoyama Sumio Kawata Wataru Kimura Satoshi Nishizuka Yoshinori Murakami 《Japanese journal of cancer research》2002,93(8):857-860
The TSLC1 (tumor suppressor in lung cancer-1) gene is a novel tumor suppressor gene on chromosomal region 11q23.2, and is frequently inactivated by concordant promoter hypermethylation and loss of heterozygosity (LOH) in non-small cell lung cancer (NSCLC). Because LOH on 11q has also been observed frequently in other human neoplasms including gastric cancer, we investigated the promoter methylation status of TSLC1 in 10 gastric cancer cell lines and 97 primary gastric cancers, as well as the corresponding non-cancerous gastric tissues, by bisulfite-SSCP analysis followed by direct sequencing. Allelic status of the TSLC1 gene was also investigated in these cell lines and primary gastric cancers. The TSLC1 promoter was methylated in two gastric cancer cell lines, KATO-III and ECC10, and in 15 out of 97 (16%) primary gastric cancers. It was not methylated in non-cancerous gastric tissues, suggesting that this hypermethylation is a cancer-specific alteration. KATO-III and ECC10 cells retained two alleles of TSLC1, both of which showed hypermethylation, associated with complete loss of gene expression. Most of the primary gastric cancers with promoter methylation also retained heterozygosity at the TSLC1 locus on 11q23.2. These data indicate that bi-allelic hypermethylation of the TSLC1 promoter and resulting gene silencing occur in a subset of primary gastric cancers. 相似文献
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Gene silencing via CpG island methylation in the promoter region is one of the mechanisms by which tumor suppressor genes are inactivated in human cancers. Previous studies have shown that the tissue inhibitors of metalloproteinases (TIMP)-2 gene, which is an endogenous inhibitor of matrix metalloproteinases involved in cell invasion and tumorigenesis, is downregulated or silenced in a variety of human cancer cell lines. Here, we investigated the mechanism underlying TIMP-2 expression in prostate cancer cell lines and primary prostate tumor samples. We observed a strong correlation between promoter hypermethylation and lost expression of TIMP-2 gene, which was supported by other results demonstrating that promoter demethylation by 5-aza-2'-deoxycytidine and trichostatin A reactivated TIMP-2 and restored its expression in TIMP-2-silenced metastatic prostate cell lines. These results were further substantiated by a chromatin immunoprecipitation assay, showing the preferential binding of MeCP2 to methylated CpG island in TIMP-2-silenced metastatic prostate cell lines. In vitro Matrigel invasion assays showed that re-expression of TIMP-2 after a combined treatment with 5-aza and trichostatin-A in metastatic prostate cells resulted in a significant reduction of tumor cell invasion. Furthermore, CpG methylation of TIMP-2 promoter was also shown in primary prostate tumors that expressed decreased TIMP-2 protein levels. These results suggest that the downregulation of the TIMP-2 gene is associated with promoter methylation and that this may play an important role in prostate cancer progression during the invasive and metastatic stages of the disease. 相似文献
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Hypermethylation of the TSLC1 Gene Promoter in Primary Gastric Cancers and Gastric Cancer Cell Lines 总被引:1,自引:0,他引:1
Teiichiro Honda Gen Tamura Takayoshi Waki Zhe Jin Kiyoshi Sato Teiichi Motoyama Sumio Kawata Wataru Kimura Satoshi Nishizuka Yoshinori Murakami 《Cancer science》2002,93(8):857-860
The TSLC1 (tumor suppressor in lung cancer–1) gene is a novel tumor suppressor gene on chromosomal region 11q23.2, and is frequently inactivated by concordant promoter hypermethylation and loss of heterozygosity (LOH) in non-small cell lung cancer (NSCLC). Because LOH on 11q has also been observed frequently in other human neoplasms including gastric cancer, we investigated the promoter methylation status of TSLC1 in 10 gastric cancer cell lines and 97 primary gastric cancers, as well as the corresponding non-cancerous gastric tissues, by bisulfite-SSCP analysis followed by direct sequencing. Allelic status of the TSLC1 gene was also investigated in these cell lines and primary gastric cancers. The TSLC1 promoter was methylated in two gastric cancer cell lines, KATO-III and ECC10, and in 15 out of 97 (16%) primary gastric cancers. It was not methylated in non-cancerous gastric tissues, suggesting that this hypermethylation is a cancer-specific alteration. KATO-III and ECC10 cells retained two alleles of TSLC1 , both of which showed hypermethylation, associated with complete loss of gene expression. Most of the primary gastric cancers with promoter methylation also retained heterozygosity at the TSLC1 locus on 11q23.2. These data indicate that bi-allelic hypermethylation of the TSLC1 promoter and resulting gene silencing occur in a subset of primary gastric cancers. 相似文献
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Sun W Iijima T Kano J Kobayashi H Li D Morishita Y Okubo C Anami Y Noguchi M 《Cancer science》2008,99(11):2177-2184
Aberrant methylation of promoter CpG islands is known to be a major inactivation mechanism of tumor-suppressor and tumor-related genes. In order to identify novel hypermethylated genes in early stage lung adenocarcinoma, we carried out methylated CpG island amplification, modified suppression subtractive hybridization, and methylation-specific polymerase chain reaction to identify aberrant methylation of CpG islands in the A/J mouse lung adenoma model, which histologically mimics the early stage of human pulmonary adenocarcinoma. Through methylated CpG island amplification, suppression subtractive hybridization, and differential screening, we detected five genes, three of which have human homologs. Two of them showed downregulation of their expression in human lung adenocarcinoma. Of these two genes, we selected sterile alpha motif domain 14 (SAMD14) and further analyzed its methylation status and expression level by methylation-specific polymerase chain reaction and quantitative real-time polymerase chain reaction. Most of the lung adenocarcinoma cell lines showed suppressed expression of SAMD14 together with hypermethylation at the promoter region, although an immortalized bronchial epithelium cell line (PL16B) did not show hypermethylation and did express SAMD14. The expression of SAMD14 in A549 was rescued by treatment with the demethylation agent 5-aza-2'-deoxycytidine. These data indicate that hypermethylation of the SAMD14 gene promoter region is associated with silencing of its expression. Hypermethylation at the CpG site of the SAMD14 promoter region was detected frequently in early invasive adenocarcinoma (8/24, 33.3%) but not in in situ adenocarcinoma (0/7, 0%) or normal lung tissue (0/31, 0%). Hypermethylation of the SAMD14 gene is a specific event in pulmonary adenocarcinogenesis and malignant progression. 相似文献
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Dickinson RE Dallol A Bieche I Krex D Morton D Maher ER Latif F 《British journal of cancer》2004,91(12):2071-2078