title: Identification of an invasion and tumor-suppressing gene, Endoglin (ENG), silenced by both epigenetic inactivation and allelic loss in esophageal squamous cell carcinoma.
abstract: Endoglin (ENG) has been identified as a candidate tumor-suppressor gene in esophageal squamous cell carcinoma (ESCC). Earlier microcell-mediated chromosome transfer (MMCT) studies of chromosome 9 in ESCC narrowed down a tumor-suppressive critical region to 9q33-34. ENG maps to 9q34-qter and encodes a transformation growth factor beta (TGFbeta) superfamily auxiliary receptor. This study aims to identify the potential role for ENG in ESCC development. Significant downregulation of ENG was detected at frequencies of 87.5% in 16 ESCC cell lines, 39.1% directly in 23 ESCC tumor specimens from Hong Kong, and 33.4% in 18 ESCC tumor specimens from the high-risk ESCC region of Henan, China. By methylation-specific PCR, methylated sequences were detected in an ESCC cell line panel and in clinical specimens. Following demethylation treatment in 9 ESCC cell lines, ENG expression was obviously restored. Loss of heterozygosity (LOH) in a 4.7 Mb region on 9q32-q34, where ENG maps, was observed directly in ESCC tumor tissues. Both epigenetic methylation and allelic loss appear to contribute to ENG downregulation in tumor cells. In vitro and in vivo functional studies such as colony formation, Matrigel culture, invasion and tumorigenicity assays were performed. Colony formation efficiency was significantly reduced by overexpression of ENG. In addition, significantly smaller colonies of ENG stable transfectants were formed in Matrigel culture. Significant suppression of invasion efficiency and tumorigenicity were also observed, when comparing the ENG stable transfectants with the vector-alone transfectants. This study provides evidence supporting ENG, as a cell invasion and tumor-suppressing gene in ESCC.
authors.affiliation: Department of Biology and Center for Cancer Research, Hong Kong University of Science and Technology, Hong Kong (SAR), PR China.
authors.forename: Victor Chun Lam
authors.initials: VC
authors.lastname: Wong
authors.forename: Pui Ling
authors.initials: PL
authors.lastname: Chan
authors.forename: Carmelo
authors.initials: C
authors.lastname: Bernabeu
authors.forename: Simon
authors.initials: S
authors.lastname: Law
authors.forename: Li Dong
authors.initials: LD
authors.lastname: Wang
authors.forename: Ji-Lin
authors.initials: JL
authors.lastname: Li
authors.forename: Sai Wah
authors.initials: SW
authors.lastname: Tsao
authors.forename: Gopesh
authors.initials: G
authors.lastname: Srivastava
authors.forename: Maria Li
authors.initials: ML
authors.lastname: Lung
mesh_terms: D000368:Aged; D015703:Antigens, CD / Q000032:analysis* / Q000235:genetics*; D015153:Blotting, Western; D002294:Carcinoma, Squamous Cell / Q000737:chemistry* / Q000235:genetics* / Q000276:immunology / Q000556:secondary; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D002681:China; D003094:Collagen; D019175:DNA Methylation; D015536:Down-Regulation; D004338:Drug Combinations; D000071063:Endoglin; D004938:Esophageal Neoplasms / Q000737:chemistry* / Q000235:genetics* / Q000473:pathology; D005260:Female; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing; D006723:Hong Kong; D006801:Humans; D007797:Laminin; D019656:Loss of Heterozygosity; D008207:Lymphatic Metastasis; D008297:Male; D018895:Microsatellite Repeats; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009367:Neoplasm Staging; D010957:Plasmids; D011401:Promoter Regions, Genetic; D011509:Proteoglycans; D011956:Receptors, Cell Surface / Q000032:analysis* / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016019:Survival Analysis; D014162:Transfection; D014410:Tumor Stem Cell Assay; D025521:Tumor Suppressor Proteins / Q000032:analysis / Q000235:genetics
chemical_list: D015703:Antigens, CD; D004338:Drug Combinations; C064206:ENG protein, human; D000071063:Endoglin; D007797:Laminin; D011509:Proteoglycans; D011956:Receptors, Cell Surface; D025521:Tumor Suppressor Proteins; C059485:matrigel; D003094:Collagen