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

Abstract

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. Key words: E-cadherin; methylation; invasion and metastasis; human tongue SCCThe results of treatment for oral squamous cell carcinomas (SCCs) have been gradually improving due to advances in cancer therapies. However, this tumor is characterized by a high degree of local invasiveness to surrounding tissues as well as a high incidence of metastasis to cervical lymph nodes 1 and consequently causes local recurrence or distant organ metastases. Therefore, the prevention and control of such invasion and metastasis are important aspects of cancer therapies for oral SCCs.The pathogenesis of cancer metastasis consists of multiple sequential steps. [2][3][4][5][6] To accomplish the process of metastasis to other organs, cancer cells first detach from the primary tumor and invade the extracellular matrix. In this step, it has been widely accepted that the reduction of E-cadherin frequently causes cell release from the primary tumor. 7,8 E-cadherin, a 120 kD cell surface glycoprotein involved in calcium-dependent epithelial cell specific cell adhesion, is well known to mediate cell-cell communication and cell-cell adhesion between epithelial cells. 9,10 The reduction in E-cadherin, which acts as an invasion suppressor in human cancer, strongly relates to invasiveness and metastasis in vitro. 8,[11][12][13] In the clin...

DNA methylation of multiple genes in gastric carcinoma: Association with histological type and CpG island methylator phenotype

“…In fact, DNA hypermethylation in the examined regions showed a good correlation with reduced expression of the respective target genes. 7,11,22,23,[33][34][35][36] In conclusion, our present results suggest that in some intestinal-and diffuse-adherent-type gastric carcinomas, DNA hypermethylation affects non-specific genes concordantly, at least in part, whereas in diffuse-scattered-type gastric carcinomas, DNA hypermethylation affects specific genes such as CDH1 and RAR-β.…”

Human FAT1 cadherin controls cell migration and invasion of oral squamous cell carcinoma through the localization of β-catenin

“…This result suggested that the deletion of FAT1 contributes to the 'cancerous' disorganized morphology of OSCCs. Therefore, limited cell to cell adhesion could result in tumors that can be easily disseminated and metastasize, as observed with the deletion of E-cadherin (21)(22)(23)(24).…”

The Epstein–Barr virus oncogene product, latent membrane protein 1, induces the downregulation of E-cadherin gene expression via activation of DNA methyltransferases

“…The proximal E-cadherin promoter (Ϫ164 to Ϫ74) that is hypermethylated in LMP1-expressing cells is seldom methylated in normal cells or early stages of cancers. In contrast, significant methylation is noted in neoplastic cells of various cancers, such as oral squamous cell carcinomas (33), prostate cancer (34), breast carcinoma (32,35), gastric carcinoma (36), and lung cancer (37). Hypermethylation of the promoter is additionally critical for reducing E-cadherin expression during the metastasis of carcinoma (23) and enhancement of the cell migration ability of epithelial tumor cell lines.…”