Browsing by Author "Tang, Moying"

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    Frequent epigenetic inactivation of chromosome 3p candidate tumor suppressor genes in gallbladder carcinoma
    (ELSEVIER IRELAND LTD, 2007) Riquelme, Erick; Tang, Moying; Baez, Sergio; Diaz, Alfonso; Pruyas, Martha; Wistuba, Ignacio I.; Corvalan, Alejandro
    Gallbladder carcinoma (GBC) is a highly malignant neoplasm that represents the leading cause of death for cancer in Chilean females. There is limited information about the molecular abnormalities involved in its pathogenesis. We have identified a number of molecular changes in GBC, including frequent allelic losses at chromosome 3p regions. Four distinct 3p sites (3p12, 3p14.2, 3p21.3 and 3p22-24) with frequent and early allelic losses in the sequential pathogenesis of this neoplasm have been detected. We investigated epigenetic and genetic abnormalities in GBC affecting 6 candidate tumor suppressor genes (TSG) located in chromosome 3p, including DUTT1 (3p12), FHIT(3p14.2), BLU, RASSF1A, SEMA3B and hMLH1 (3p21.3). DNA extracted from frozen tissue obtained from 50 surgical resected GBCs was examined for gene promoter methylation using MSP (methylation-specific PCR) technique after bisulfite treatment in all 6 genes. In addition, we performed PCR-based mutation examination using SSCP in FHIT and RASSF1A genes and loss of heterozygosity (LOH) analysis using microdissected tissue in a subset of tumors for the 3p21.3 region with 8 microsatellite markers. A very high frequency of GBC methylation was detected in SEMA3B (46/50, 92%) and FHIT (33/50, 66%), inter-mediate incidences in BLU (13/50, 26%) and DUTT1 (11/50, 22%) and very low frequencies in RASSF1A (4/50, 8%) and hMLH1 (2/50, 4%). Allelic loss at 3p21.3 was found in nearly half of the GBCs examined. We conclude that epigenetic inactivation by abnormal promoter methylation is a frequent event in chromosome 3p candidate TSGs in GBC pathogenesis, especially affecting genes SEMA3B (3p21.3) and FHIT (3p 14.2). (c) 2006 Elsevier Ireland Ltd. All rights reserved.
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    Mitochondrial DNA mutation at the D310 (displacement loop) mononucleotide sequence in the pathogenesis of gallbladder carcinoma
    (2004) Tang, Moying; Baez, S; Pruyas Arieda, Martha; Diaz, A; Calvo, A; Riquelme Sánchez, Erick Marcelo; Wistuba, Oyarzún Ignacio
    Purpose: Mutations in the mitochondrial DNA (mtDNA) have been observed frequently in human neoplasia, in both coding and noncoding regions. A mononucleotide repeat (poly-C) between 303 and 315 nucleotides (D310) within the regulatory displacement loop has been identified recently as a frequent hot spot of deletion/insertion mutations in tumors. We investigated the frequency and pattern of D310 abnormalities in the pathogenesis of gallbladder carcinoma (GBC). Experimental Design: DNA extracted from neoplastic and nonneoplastic archival gallbladder tissue including 123 tumors, 53 dysplastic areas, and 90 histologically normal epithelia adjacent to GBC, chronic cholecystitis, and 15 normal gallbladders were examined by PCR-based assay for D310 mutations, followed by sequencing in a subset of cases. Results: D310 mutation was a relatively frequent (47 of 123; 38%) abnormality in GBC. A very high frequency of mutations were detected in dysplastic (8 of 14; 57%) and normal-appearing gallbladder epithelia (10 of 22; 46%) accompanying GBC, showing a clonal relationship compared with the corresponding tumors. D310 mutations were also detected in dysplastic (8 of 39; 21%) and normal (17 of 68; 25%) epithelia obtained from chronic cholecystitis. A single case of 15 normal gallbladders showed a D310 abnormality. Overall, deletions (67 of 91; 74%) at D310 were more frequent than insertions. Conclusions: D310 mutation at the mtDNA displacement loop is a relatively frequent and early event in the sequential pathogenesis of GBC, being detected in normalappearing epithelium from chronic cholecystitis. Our findReceived 4/28/03; revised 11/3/03; accepted 11/4/03. Grant support: Grant FONDECYT (Fondo Nacional de Desarrollo Cientifico y Tecnologico) #1020960. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. Requests for reprints: Ignacio I. Wistuba, Department of Pathology, M.D. Anderson Cancer Center, 1515 Holcombe Boulevard, Unit 85, Houston, TX 77030-4009. Phone: (713) 563-1659; Fax: (713) 7923184; E-mail: iiwistuba@mdanderson.org. ings suggest that mtDNA mutations should be additionally investigated in GBC pathogenesis, and D310 mononucleotide abnormalities could be included in a panel of molecular biomarkers for GBC early detection strategy.