Epigenetic silencing of JAM3 promotes esophageal cancer development by activating Wnt signaling.

BACKGROUND: The role of JAM3 in different tumors is controversial. The epigenetic regulation and the mechanism of JAM3 remain to be elucidated in human esophageal cancer (EC). METHODS: Eleven EC cell lines, 49 cases of esophageal intraepithelial neoplasia (EIN) and 760 cases of primary EC samples were employed. Methylation-specific polymerase chain reaction, immunohistochemistry, MTT, western blot and xenograft mouse models were applied in this study. RESULTS: The inverse association between RNA expression and promoter region methylation of JAM3 was found by analyzing 185 cases of EC samples extracted from the TCGA database (p < 0.05). JAM3 was highly expressed in KYSE450, KYSE520, TE1 and YES2 cells, low level expressed in KYSE70 cells and unexpressed in KYSE30, KYSE150, KYSE410, KYSE510, TE13 and BIC1 cells. JAM3 was unmethylated in KYSE450, KYSE520, TE1 and YES2 cells, partial methylated in KYSE70 cells and completely methylated in KYSE30, KYSE150, KYSE410, KYSE510, TE13 and BIC1 cells. The expression of JAM3 is correlated with methylation status. The levels of JAM3 were unchanged in KYSE450, KYSE520, TE1 and YES2 cells, increased in KYSE70 cells and restored expression in KYSE30, KYSE150, KYSE410, KYSE510, TE13 and BIC1 cells after 5-aza-2'-deoxycytidine treatment, suggesting that the expression of JAM3 is regulated by promoter region methylation. JAM3 was methylated in 26.5% (13/49) of EIN and 51.1% (388/760) of primary EC, and methylation of JAM3 was associated significantly with tumor differentiation and family history (all p < 0.05). Methylation of JAM3 is an independent prognostic factor of poor 5-year overall survival (p < 0.05). JAM3 suppresses cell proliferation, colony formation, migration and invasion and induces G1/S arrest and apoptosis in EC. Further study demonstrated that JAM3 suppressed EC cells and xenograft tumor growth by inhibiting Wnt/ß-catenin signaling. CONCLUSION: JAM3 is frequently methylated in human EC, and the expression of JAM3 is regulated by promoter region methylation. JAM3 methylation is an early detection and prognostic marker of EC. JAM3 suppresses EC growth both in vitro and in vivo by inhibiting Wnt signaling.

SOX17 methylation inhibits its antagonism of Wnt signaling pathway in lung cancer.

The purpose of this study was to explore epigenetic changes and functions of SOX17 in human lung cancer. Five lung cancer cell lines and 88 primary lung cancer samples were examined in this study. Methylation-specific polymerase chain reaction (MSP), semi-quantitative reverse-transcription PCR, immunohistochemistry, luciferase reporter assays, colony-formation assays, and western blotting were used to analyze methylation changes and functions of SOX17 in lung cancer. SOX17 methylation was found in 60.2% of primary human lung cancer samples, and promoter region methylation of SOX17 silenced its expression. SOX17 methylation was associated with female patients and lung cancer differentiation. Colony-formation assays revealed that SOX17 suppressed lung cancer cell proliferation. Re-expression of SOX17 inhibited Wnt signaling in H23 lung cancer cell line. SOX17 acts as a Wnt signaling inhibitor.