title: 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: Department of Oncology, Zhongnan Hospital, Wuhan University, Wuhan 430070, PR China.
authors: Yiling
authors: Y
authors: Huang
authors: Huamei
authors: H
authors: Song
authors: Huojun
authors: H
authors: Hu
authors: Lei
authors: L
authors: Cui
authors: Chengcheng
authors: C
authors: You
authors: Liming
authors: L
authors: Huang
mesh_terms: D025601:Adenomatous Polyposis Coli Protein / Q000235:genetics / Q000378:metabolism; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D000075982:Cell Adhesion Molecule-1; D015815:Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D019175:DNA Methylation / Q000187:drug effects*; D005260:Female; D006367:HeLa Cells; D006801:Humans; D007136:Immunoglobulins / Q000235:genetics / Q000378:metabolism; D015978:Trichosanthin / Q000494:pharmacology*; D002583:Uterine Cervical Neoplasms / Q000378:metabolism / Q000473:pathology
chemical_list: D025601:Adenomatous Polyposis Coli Protein; D000972:Antineoplastic Agents, Phytogenic; C403514:CADM1 protein, human; D000075982:Cell Adhesion Molecule-1; D015815:Cell Adhesion Molecules; D007136:Immunoglobulins; D015978:Trichosanthin; D004248:DNA (Cytosine-5-)-Methyltransferases