title: Emodin, aloe-emodin and rhein induced DNA damage and inhibited DNA repair gene expression in SCC-4 human tongue cancer cells.
abstract: In our primary studies, we have shown that emodin, aloe-emodin and rhein induced cytotoxic effects, including cell cycle arrest and apoptosis in SCC-4 human tongue cancer cells. However, details regarding their effects on DNA damage and repair gene expression in SCC-4 cells are not clear. We investigated whether or not emodin, aloe-emodin and rhein induced DNA damage and inhibited DNA repair gene expression in SCC-4 cells. Comet assay (single cell electrophoresis) indicated that incubation of SCC-4 cells with 0, 20, 30 and 40 microM of emodin, 0, 25, 50 and 100 microM of aloe-emodin or rhein led to a longer DNA migration smear (comet tail). This means that all examined agents induced DNA damage in SCC-4 cells and these effects are dose-dependent but emodin is stronger than that of aloe-emodin or rhein. The results from real-time PCR assay demonstrated that 30 microM of emodin or aloe-emodin used for 24 and 48 h treatment in SCC-4 cells significantly inhibited expression of genes associated with DNA damage and repair [ataxia telangiectasia mutated (ATM); ataxia-telangiectasia and Rad3-related (ATR); 14-3-3sigma (14-3-3sigma); breast cancer 1, early onset (BRCA1); and DNA-dependent serine/threonine protein kinase (DNA-PK)]; only rhein suppressed the expression of O(6)-methylguanine-DNA methyltransferase (MGMT) mRNA with 48 h treatment, but had no effect on ATM expression. On 24 h treatment, only aloe-emodin significantly affected ATM expression. These effects may be the vital factors for emodin, aloe-emodin and rhein induction of DNA damage in vitro. In conclusion, these agents induced DNA damage followed by the inhibition of DNA repair-associated gene expressions, including ATM, ATR, 14-3-3sigma, BRCA1, DNA-PK and MGMT in SCC-4 human tongue cancer cells.
authors.affiliation: China Medical University, No 91, Hsueh-Shih Road, Taichung 404, Taiwan.
authors.forename: Ya-Yin
authors.initials: YY
authors.lastname: Chen
authors.forename: Su-Yin
authors.initials: SY
authors.lastname: Chiang
authors.forename: Jaung-Geng
authors.initials: JG
authors.lastname: Lin
authors.forename: Jai-Sing
authors.initials: JS
authors.lastname: Yang
authors.forename: Yi-Shih
authors.initials: YS
authors.lastname: Ma
authors.forename: Ching-Lung
authors.initials: CL
authors.lastname: Liao
authors.forename: Tung-Yuan
authors.initials: TY
authors.lastname: Lai
authors.forename: Nou-Ying
authors.initials: NY
authors.lastname: Tang
authors.forename: Jing-Gung
authors.initials: JG
authors.lastname: Chung
mesh_terms: D048948:14-3-3 Proteins; D000880:Anthraquinones / Q000494:pharmacology*; D064007:Ataxia Telangiectasia Mutated Proteins; D019313:BRCA1 Protein / Q000096:biosynthesis / Q000235:genetics; D014408:Biomarkers, Tumor / Q000096:biosynthesis / Q000235:genetics; D018797:Cell Cycle Proteins / Q000096:biosynthesis / Q000235:genetics; D045744:Cell Line, Tumor; D020552:Comet Assay; D004249:DNA Damage; D015254:DNA Modification Methylases / Q000096:biosynthesis / Q000235:genetics; D004260:DNA Repair / Q000187:drug effects / Q000235:genetics; D045643:DNA Repair Enzymes / Q000037:antagonists & inhibitors* / Q000096:biosynthesis / Q000235:genetics; D051747:DNA-Activated Protein Kinase / Q000096:biosynthesis / Q000235:genetics; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics; D004642:Emodin / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005092:Exonucleases / Q000096:biosynthesis / Q000235:genetics; D005095:Exoribonucleases; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D009363:Neoplasm Proteins / Q000096:biosynthesis / Q000235:genetics; D016133:Polymerase Chain Reaction; D017346:Protein Serine-Threonine Kinases / Q000096:biosynthesis / Q000235:genetics; D014062:Tongue Neoplasms / Q000188:drug therapy* / Q000235:genetics* / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000037:antagonists & inhibitors* / Q000096:biosynthesis / Q000235:genetics
chemical_list: D048948:14-3-3 Proteins; D000880:Anthraquinones; D019313:BRCA1 Protein; D014408:Biomarkers, Tumor; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D009363:Neoplasm Proteins; D025521:Tumor Suppressor Proteins; C518327:aloe emodin; D015254:DNA Modification Methylases; C515491:MGMT protein, human; C576324:ATM protein, human; C576597:ATR protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D051747:DNA-Activated Protein Kinase; D017346:Protein Serine-Threonine Kinases; D005092:Exonucleases; D005095:Exoribonucleases; C413442:SFN protein, human; D045643:DNA Repair Enzymes; D004642:Emodin; C020491:rhein