title: SC-III3, a novel scopoletin derivative, induces cytotoxicity in hepatocellular cancer cells through oxidative DNA damage and ataxia telangiectasia-mutated nuclear protein kinase activation.
abstract: BACKGROUND
  Natural products from plants have been proven to be important resources of antitumor agents. In this study, we exploited the antitumor activity of (E)-3-(4-chlorophenyl)-N-(7-hydroxy-6-methoxy-2-oxo-2H-chromen-3-yl) acrylamide (SC-III3), a newly synthesized derivative of scopoletin, by in vitro and in vivo experiments.
  
  
  METHODS
  Human hepatocellular carcinoma cell line HepG2 cells and xenograft of HepG2 cells in BALB/c nude mice were used to investigate the effects of SC-III3 on hepatocellular cancers. Cell cycle arrest and apoptosis were analyzed by flow cytometry. Cell cycle arrest, apoptosis and ATM-Chk pathway-related proteins were characterized by western blot.
  
  
  RESULTS
  SC-III3 selectively inhibited the viability of HepG2 cells without significant cytotoxicity against human normal liver cells LO2. In mouse xenograft model of HepG2 cells, SC-III3 showed a marked inhibition of tumor growth in a dose-dependent manner. Cell cycle analysis revealed that SC-III3 induced cells to accumulate in S phase, which was accompanied by a marked decrease of the expressions of cyclin A, cyclin B, cyclin E and Cdk2 proteins, the crucial regulators of S phase cell cycle. SC-III3 treatment resulted in DNA breaks in HepG2 cells, which might contribute to its S phase arrest. The S arrest and the activation of ATM-Chk1/Chk2-Cdc25A-Cdk2 pathways induced by SC-III3 in HepG2 cells could be efficiently abrogated by pretreatments of either Ku55933 (an inhibitor of ATM) or UCN-01 (an inhibitor of Chk1/Chk2). The activation of p53-p21 pathway by SC-III3 was also reversed by Ku55933 treatment. SC-III3 led to significant accumulation of intracellular reactive oxygen species (ROS), a breaker of DNA strand, in HepG2 cells but not LO2 cells. Pretreatment with N-acetyl-l-cysteine (NAC), a ROS scavenger, could reverse SC-III3-caused ROS accumulation, DNA damage, activation of signal pathways relevant to DNA damage, S phase arrest and cell viability decrease in HepG2 cells.
  
  
  CONCLUSIONS
  SC-III3 is able to efficiently inhibit the growth of hepatocellular carcinoma through inducing the generation of intracellular ROS, DNA damage and consequent S phase arrest, but lack of significant cytotoxicity against normal liver cells. This compound deserves further studies as a candidate of anticancer drugs.
authors.forename: Peng
authors.initials: P
authors.lastname: Zhao
authors.forename: Li
authors.initials: L
authors.lastname: Chen
authors.forename: Lin-Hu
authors.initials: LH
authors.lastname: Li
authors.forename: Zhi-Feng
authors.initials: ZF
authors.lastname: Wei
authors.forename: Bei
authors.initials: B
authors.lastname: Tong
authors.forename: Yu-Gai
authors.initials: YG
authors.lastname: Jia
authors.forename: Ling-Yi
authors.initials: LY
authors.lastname: Kong
authors.affiliation: Department of Pharmacology of Chinese Materia Medica, China Pharmaceutical University, 24 Tong Jia Xiang, Nanjing 210009, China. yfxiacpu@126.com.
authors.forename: Yu-Feng
authors.initials: YF
authors.lastname: Xia
authors.forename: Yue
authors.initials: Y
authors.lastname: Dai
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000138:chemical synthesis / Q000494:pharmacology*; D064007:Ataxia Telangiectasia Mutated Proteins / Q000235:genetics; D006528:Carcinoma, Hepatocellular / Q000188:drug therapy* / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects; D045744:Cell Line, Tumor; D002934:Cinnamates / Q000138:chemical synthesis / Q000494:pharmacology*; D004249:DNA Damage / Q000187:drug effects; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D056945:Hep G2 Cells; D006801:Humans; D008113:Liver Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D051379:Mice; D008819:Mice, Nude; D009025:Morpholines / Q000494:pharmacology; D011753:Pyrones / Q000494:pharmacology; D012603:Scopoletin / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects; D023041:Xenograft Model Antitumor Assays
chemical_list: C495818:2-morpholin-4-yl-6-thianthren-1-yl-pyran-4-one; C000600170:3-(4-chlorophenyl)-N-(7-hydroxy-6-methoxy-2-oxo-2H-chromen-3-yl)acrylamide; D000970:Antineoplastic Agents; D002934:Cinnamates; D009025:Morpholines; D011753:Pyrones; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D012603:Scopoletin