Wenji Yan

Epigenetic silencing of DACH1 induces loss of transforming growth factor‐β1 antiproliferative response in human hepatocellular carcinoma

Human dachshund homolog 1 (DACH1) is a major component of the Retinal Determination Gene Network (RDGN) and functions as a tumor suppressor. However, the regulation of DACH1 expression and its function in hepatocellular carcinoma (HCC) remain unclear. In this study, epigenetic changes of DACH1 were analyzed in HCC cell lines and primary cancers. We found that promoter region hypermethylation was correlated with loss or reduction of DACH1 expression, and restoration of DACH1 expression was induced by 5‐aza‐2′‐deoxycytidine (5‐AZA) in HCC cell lines. Promoter region methylation was found in 42% of primary HCC. Reduced expression of DACH1 was associated with poor differentiation of HCC nodules and higher serum aspartate aminotransferase/alanine aminotransferase ratio. DACH1 suppressed cellular growth by reactivating transforming growth factor beta (TGF‐β) signaling. Ectopic expression of DACH1 enhanced chemosensitivity to 5‐fluorouracil (5‐FU) by inducing p21 expression in HCC cells. Conclusion: DACH1 is frequently methylated in HCC and DACH1 expression is regulated by promoter hypermethylation. Down‐regulation of DACH1 is a novel mechanism for gaining resistance to the antiproliferative signaling of TGF‐β1 and 5‐FU resistance. (Hepatology 2013; 58:2012–2022)

Epigenome-based personalized medicine in human cancer

Cancer genome sequencing has created an opportunity for precision medicine. Thus far, genetic alterations can only be used to guide treatment for small subsets of certain cancer types with these key alterations. Similar to mutations, epigenetic events are equally suitable for personalized medicine. DNA methylation alterations have been used to identify tumor-specific drug responsive markers. Methylation of MGMT sensitizes gliomas to alkylating agents is an example of epigenetic personalized medicine. Recent studies have revealed that 5-azacytidine and decitabine show activity in myelodysplasia, lung and other cancers. There are currently at least 20 kinds of histone deacetylase inhibitors in clinical testing. Inhibitors targeting other epigenetic regulators are being clinically tested, such as EZH2 inhibitor EPZ-6438.

Silencing DACH1 Promotes Esophageal Cancer Growth by Inhibiting TGF-β Signaling

Human Dachshund homologue 1 (DACH1) is a major component of the Retinal Determination Gene Network. Loss of DACH1 expression was found in breast, prostate, lung, endometrial, colorectal and hepatocellular carcinoma. To explore the expression, regulation and function of DACH1 in human esophageal cancer, 11 esophageal cancer cell lines, 10 cases of normal esophageal mucosa, 51 cases of different grades of dysplasia and 104 cases of primary esophageal squamous cancer were employed. Methylation specific PCR, immunohistochemistry, western blot, flow cytometry, small interfering RNAs, colony formation techniques and xenograft mice model were used. We found that DACH1 expression was regulated by promoter region hypermethylation in esophageal cancer cell lines. 18.8% (6 of 32) of grade 1, 42.1% (8 of 19) of grade 2 and grade 3 dysplasia (ED2,3), and 61.5% (64 of 104) of esophageal cancer were methylated, but no methylation was found in 10 cases of normal esophageal mucosa. The methylation was increased in progression tendency during esophageal carcinogenesis (P<0.01). DACH1 methylation was associated with poor differentiation (P<0.05) and late tumor stage (P<0.05). Restoration of DACH1 expression inhibited cell growth and activated TGF-β signaling in KYSE150 and KYSE510 cells. DACH1 suppressed human esophageal cancer cell tumor growth in xenograft mice. In conclusion, DACH1 is frequently methylated in human esophageal cancer and methylation of DACH1 is involved in the early stage of esophageal carcinogenesis. DACH1 expression is regulated by promoter region hypermethylation. DACH1 suppresses esophageal cancer growth by activating TGF-β signaling.

Retinoic acid-induced 2 (RAI2) is a novel tumor suppressor, and promoter region methylation of RAI2 is a poor prognostic marker in colorectal cancer

BackgroundReduced expression of retinoic acid-induced 2 (RAI2) was found in breast cancer. The regulation and function of RAI2 in human colorectal cancer (CRC) remain unclear.MethodsEight CRC cell lines and 237 cases of primary CRC were analyzed. Methylation-specific PCR (MSP), flow cytometry, xenograft mouse model, and shRNA technique were employed.ResultsRAI2 was completely methylated in RKO, LOVO, and HCT116 cells; partially methylated in HT29 cells; and unmethylated in SW480, SW620, DLD1, and DKO cells. RAI2 was methylated in 53.6% (127/237) of primary colorectal cancer. Methylation of RAI2 was significantly associated with gender (P < 0.001), TNM stage (P < 0.001), and lymph node metastasis (P < 0.001). Analyzing by the Kaplan-Meier method, methylation of RAI2 was significantly associated with poor 5-year overall survival (OS) (P = 0.0035) and 5-year relapse-free survival (RFS) (P = 0.0062). According to Cox proportional hazards model analysis, RAI2 methylation was an independent poor prognostic marker for 5-year OS (P = 0.002) and poor 5-year RFS (P = 0.022). RAI2 suppressed cell proliferation, migration, and invasion and induced cell apoptosis in CRC. In addition, RAI2 inhibited AKT signaling in CRC cells and suppressed human CRC cell xenograft growth in mice.ConclusionRAI2 is frequently methylated in human CRC, and the expression of RAI2 is regulated by promoter region methylation. Methylation of RAI2 is an independent poor prognostic marker of CRC. RAI2 suppresses CRC cell growth both in vitro and in vivo. RAI2 suppresses CRC by inhibiting AKT signaling.

Abstract 2974: Epigenetic silencing DACH1 activated both TGF-β and Wnt signaling in colorectal cancer.

Background Colorectal cancer (CRC) is the second leading cause of cancer-related deaths in the Western countries. The incidence of CRC is increasing very fast with the changing of diet and life style in China. Both Wnt and TGF-β signaling pathways were regarded to play important roles in the development of colorectal cancer. Recent studies have found that the TGF-β and Wnt signaling pathways are crosstalking during breast cancer carcinogenesis and other situations. DACH1 was found inhibiting TGF-β signaling in breast and ovarian cancer. The epigenetic regulation and the function of DACH1 in colorectal cancer remain unclear. Objective To evaluate the possibility of DACH1 methylation serving as CRC detection marker and the regulation of DACH1 expression in colorectal cancer, the role of DACH1 in TGF-β W 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2974. doi:10.1158/1538-7445.AM2013-2974

Molecular Biology Character of Esophageal Cancer

Esophageal cancer (EC) is the eighth most common cancer and the sixth most common cause of cancer death worldwide. Esophageal squamous cell carcinoma (ESCC) and adenocarcinoma (EAC) are two major histopathological type of esophageal cancer. The incidence of EC was increased in the past 3 decades. Five-year survival of advanced cancer is still very poor, even though improved surgical techniques and adjuvant chemoradiation therapy. It is very important to understand esophageal cancer biology.