The E‐cadherin gene is silenced by CpG methylation in human oral squamous cell carcinomas

• Published in: International journal of cancer Vol. 93; no. 5; pp. 667 - 673
• Main Authors: Nakayama, Shuko, Sasaki, Akira, Mese, Hiroshi, Alcalde, Rafael E., Tsuji, Takanori, Matsumura, Tomohiro
• Format: Journal Article
• Language: English
• Published: New York John Wiley & Sons, Inc 01-09-2001; Wiley-Liss
• Subjects: Antimetabolites, Antineoplastic - pharmacology; Azacitidine - pharmacology; Biological and medical sciences; Cadherins - biosynthesis; Cadherins - drug effects; Cadherins - genetics; Carcinoma, Squamous Cell - genetics; Carcinoma, Squamous Cell - metabolism; CpG Islands - genetics; DNA Methylation; E-cadherin; Esophagus; Gastroenterology. Liver. Pancreas. Abdomen; Gene Expression Regulation, Neoplastic - drug effects; Gene Silencing; human tongue SCC; Humans; invasion and metastasis; Medical sciences; methylation; Mouth Neoplasms - genetics; Mouth Neoplasms - metabolism; Promoter Regions, Genetic - drug effects; Promoter Regions, Genetic - genetics; Tumor Cells, Cultured - drug effects; Tumors; Human; Squamous cell carcinoma; Nucleotide sequence; Esophageal disease; Cell adhesion molecule; Malignant tumor; Metastasis; Esophagus; Gene silencing; Gene; GC rich sequence; Digestive diseases; Genetics; Methylation; E Cadherin
• ISSN: 0020-7136; 1097-0215
• DOI: 10.1002/ijc.1386

Reduction of E‐cadherin strongly relates to invasiveness and metastasis in vitro. To clarify CpG methylation around the promoter region of the E‐cadherin gene in oral squamous cell carcinoma (SCC), we examined the DNA samples of various human SCC cell lines and primary oral SCC tissues by methylation‐specific polymerase chain reaction (MSP). CpG methylation of the E‐cadherin gene markedly correlated to the reduction of E‐cadherin expression in human oral SCC cell lines. In primary oral SCC tissues, only 1 of 5 preserved E‐cadherin‐expressing tissues was methylated, whereas methylation was found in 17 (94.4%) of 18 E‐cadherin‐reduced tissues. Our results suggest that reduction of E‐cadherin expression is associated with CpG methylation of the E‐cadherin gene promoter. We recently established two cell lines with high and low metastatic potential, UM1 and UM2, from SCC primary tongue tissue of a patient. E‐cadherin expression of high‐metastatic UM1 was clearly lower than that of low‐metastatic UM2, and MSP results showed CpG methylation in the UM1 but not the UM2 cell line. To investigate whether demethylation of CpG methylation of the E‐cadherin gene could restore expression and function of E‐cadherin, we treated UM1 with the demethylating agent 5‐azacytidine (5‐aza) and found that E‐cadherin expression was indeed restored by demethylation. Moreover, in the demethylated UM1, invasion of the collagen gel was clearly suppressed compared with the untreated UM1. These results suggested that inactivation of E‐cadherin expression resulted from CpG methylation of the gene promoter; a correlation between CpG methylation of the E‐cadherin gene promoter and invasive potential was also suggested. © 2001 Wiley‐Liss, Inc.