Trichosanthin inhibits DNA methyltransferase and restores methylation-silenced gene expression in human cervical cancer cells.

Abstract

Epigenetic silencing of tumor suppressor genes is a well-established oncogenic process and the reactivation of tumor suppressor genes that have been silenced by promoter methylation is an attractive molecular target for cancer therapy. In this study, we investigated the demethylation activity of trichosanthin (TCS, the main bioactive component isolated from a Chinese medicinal herb) and its possible mechanism of action in cervical cancer cell lines. HeLa human cervical adenocarcinoma and CaSki human cervical squamous carcinoma cells were treated with various concentrations (0, 20, 40 and 80 µg/ml) of TCS for 48 h and the mRNA and protein expression levels of the tumor suppressor genes adenomatous polyposis coli (APC) and tumor suppressor in lung cancer 1 (TSLC1) were detected using reverse transcription (RT)-PCR and western blotting, respectively. We analyzed the methylation status of APC and TSLC1 using methylation-specific PCR (MSP). The expression levels and enzyme activity of DNA methyltransferase 1 (DNMT1) were also examined. The mRNA and protein expression levels of APC and TSLC1 were increased following treatment with various concentrations (0, 20, 40 and 80 µg/ml) of TCS for 48 h. The expression of the APC gene increased 2.55±0.29-, 3.44±0.31- and 4.36±0.14-fold, respectively. The expression of the TSLC1 gene increased 2.28±0.15-, 4.23±0.88- and 6.09±0.23-fold, respectively. MSP detection showed that TCS induced demethylation in HeLa and CaSki cells and that this demethylation activity was accompanied by the decreased expression of DNMT1 and reduced DNMT1 enzyme activity. Our experimental results demonstrate for the first time that TCS is capable of restoring the expression of methylation-silenced tumor suppressor genes and is potentially useful as a demethylation agent for the clinical treatment of human cervical cancer.

• Authors: Yiling Huang, Huamei Song, Huojun Hu, Lei Cui, Chengcheng You, Liming Huang
• Journal: Molecular medicine reports (Mol Med Rep) Vol. 6 Issue 4 Pg. 872-8 (Oct 2012) ISSN: 1791-3004 [Electronic] Greece
• PMID: 22825485 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Adenomatous Polyposis Coli Protein
• Antineoplastic Agents, Phytogenic
• CADM1 protein, human
• Cell Adhesion Molecule-1
• Cell Adhesion Molecules
• Immunoglobulins
• Trichosanthin
• DNA (Cytosine-5-)-Methyltransferases

Topics

• Adenomatous Polyposis Coli Protein (genetics, metabolism)
• Antineoplastic Agents, Phytogenic (pharmacology)
• Cell Adhesion Molecule-1
• Cell Adhesion Molecules (genetics, metabolism)
• Cell Line, Tumor
• DNA (Cytosine-5-)-Methyltransferases (antagonists & inhibitors, metabolism)
• DNA Methylation (drug effects)
• Female
• HeLa Cells
• Humans
• Immunoglobulins (genetics, metabolism)
• Trichosanthin (pharmacology)
• Uterine Cervical Neoplasms (metabolism, pathology)