E-cadherin mutation and Snail overexpression as alternative mechanisms of E-cadherin inactivation in synovial sarcoma

• Published in: Oncogene Vol. 23; no. 53; pp. 8629 - 8638
• Main Authors: SAITO, Tsuyoshi, ODA, Yoshinao, TSUNEYOSHI, Masazumi, KAWAGUCHI, Ken-Ichi, SUGIMACHI, Keishi, YAMAMOTO, Hidetaka, TATEISHI, Naomi, TANAKA, Kazuhiro, MATSUDA, Shuichi, IWAMOTO, Yukihide, LADANYI, Marc
• Format: Journal Article
• Language: English
• Published: Basingstoke Nature Publishing 11.11.2004; Nature Publishing Group
• Subjects: Biological and medical sciences; Cadherins - genetics; Cadherins - metabolism; Cancer; Cell morphology; Cell physiology; Cell transformation and carcinogenesis. Action of oncogenes and antioncogenes; Conformation; CpG Islands - genetics; Cytology; Diseases of the osteoarticular system; DNA Methylation; DNA microarrays; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; E-cadherin; Epigenetics; Fundamental and applied biological sciences. Psychology; Gene expression; Gene Expression Regulation, Neoplastic; Histology; Humans; Immunohistochemistry; Medical sciences; Missense mutation; Molecular and cellular biology; Morphology; Mutation; Mutation - genetics; Oncogene Proteins, Fusion - genetics; Oncogene Proteins, Fusion - metabolism; Pathology; Polymerase chain reaction; Promoter Regions, Genetic - genetics; Proto-Oncogene Proteins - genetics; Proto-Oncogene Proteins c-ets; RNA, Messenger - genetics; RNA, Messenger - metabolism; Sarcoma; Sarcoma, Synovial - genetics; Sarcoma, Synovial - metabolism; Sarcoma, Synovial - pathology; Snail Family Transcription Factors; Snail protein; Synovial sarcoma; Transcription Factors - genetics; Transcription Factors - metabolism; Tumors; Tumors of striated muscle and skeleton; New York; United States > US; Japan; Synovial sarcoma; Diseases of the osteoarticular system; Gene overexpression; Epithelium; Inactivation; Snail; Carcinogenesis; E-cadherin; Mechanism; CpG methylation; ELF3; epithelial-mesenchymal transition; Mutation; Methylation; E Cadherin
• ISSN: 0950-9232; 1476-5594
• DOI: 10.1038/sj.onc.1207960

We have recently reported frequent E-cadherin gene mutations in synovial sarcoma (SS), suggesting mutational inactivation of E-cadherin as a potential mechanism of spindle cell morphology in SS, a spindle cell sarcoma that shows areas of glandular epithelial differentiaton in some cases (biphasic SS) and only pure spindle cell morphology in most cases (monophasic SS). However, the mechanism of downregulation of E-cadherin in SS remains unknown. To further address this issue, we analysed the mechanisms of E-cadherin silencing in 40 SS. Genetic and epigenetic changes in the E-cadherin gene, and the expression level of its transcriptional repressor Snail were examined by polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP), methylation-specific PCR, and real-time quantitative PCR, respectively. Expression of E-cadherin was examined by RT-PCR and immunohistochemistry. We also examined ELF3, a transcription factor associated with epithelial differentiation in SS in a previous cDNA microarray, by RT-PCR. E-cadherin and ELF3 transcripts were detected, respectively, in 27/40 (67.5%) and in 25/40 (62.5%) of SS, and these epithelial-related genes were almost always coexpressed. Hypermethylation of the promoter of the E-cadherin gene was detected in five cases (12.5%) in SS; however, E-cadherin was silenced at mRNA level in only one of the five cases. E-cadherin missense mutations were observed in five cases (12.5%) of SS. In SS, all five cases with E-cadherin missense mutations had the SYT-SSX1 fusion and were monophasic tumors, suggesting a relationship between the SYT-SSX fusion type and E-cadherin missense mutation (P=0.07). E-cadherin mRNA expression in SS was associated with reduced Snail expression level (P=0.03). E-cadherin membranous expression was observed in 14/40 (35.0%) of SS, and was also correlated with SYT-SSX1 fusion type and biphasic histology. ELF3 was confirmed to be more highly expressed in biphasic than monophasic SS by real-time quantitative PCR. These results suggest that in SS the loss of E-cadherin expression occurs either by Snail trans-repression or by inactivating mutations. Thus, E-cadherin downregulation is associated with the loss or absence of glandular epithelial differentiation in certain SS.