title: Emodin regulating excision repair cross-complementation group 1 through fibroblast growth factor receptor 2 signaling.
abstract: OBJECTIVE
  To investigate the molecular mechanisms underlying the reversal effect of emodin on platinum resistance in hepatocellular carcinoma.
  
  
  METHODS
  After the addition of 10 μmol/L emodin to HepG2/oxaliplatin (OXA) cells, the inhibition rate (IR), 50% inhibitory concentration (IC₅₀) and reversal index (IC₅₀ in experimental group/IC₅₀ in control group) were calculated. For HepG2, HepG2/OXA, HepG2/OXA/T, each cell line was divided into a control group, OXA group, OXA + fibroblast growth factor 7 (FGF7) group and OXA + emodin group, and the final concentrations of FGF7, emodin and OXA in each group were 5 ng/mL, 10 μg/mL and 10 μmol/L, respectively. Single-cell gel electrophoresis was conducted to detect DNA damage, and the fibroblast growth factor receptor 2 (FGFR2), phosphorylated extracellular signal-regulated kinase 1/2 (p-ERK1/2) and excision repair cross-complementing gene 1 (ERCC1) protein expression levels in each group were examined by Western blotting.
  
  
  RESULTS
  Compared with the IC₅₀ of 120.78 μmol/L in HepG2/OXA cells, the IC₅₀ decreased to 39.65 μmol/L after treatment with 10 μmol/L emodin; thus, the reversal index was 3.05. Compared with the control group, the tail length and Olive tail length in the OXA group, OXA + FGF7 group and OXA + emodin group were significantly increased, and the differences were statistically significant (P < 0.01). The tail length and Olive tail length were lower in the OXA + FGF7 group than in the OXA group, and this difference was also statistically significant. Compared with the OXA + FGF7 group, the tail extent, the Olive tail moment and the percentage of tail DNA were significantly increased in the OXA + emodin group, and these differences were statistically significant (P < 0.01). In comparison with its parental cell line HepG2, the HepG2/OXA cells demonstrated significantly increased FGFR2, p-ERK1/2 and ERCC1 expression levels, whereas the expression of all three molecules was significantly inhibited in HepG2/OXA/T cells, in which FGFR2 was silenced by FGFR2 shRNA. In the examined HepG2 cells, the FGFR2, p-ERK1/2 and ERCC1 expression levels demonstrated increasing trends in the OXA group and OXA + FGF7 group. Compared with the OXA group and OXA + FGF7 group, the FGFR2, p-ERK1/2, and ERCC1 expression levels were significantly lower in the OXA + emodin group, and these differences were statistically significant. In the HepG2/OXA/T cell line that was transfected with FGFR2 shRNA, the FGFR2, p-ERK1/2 and ERCC1 expression levels were significantly inhibited, but there were no significant differences in these expression levels among the OXA, OXA + FGF7 and OXA + emodin groups.
  
  
  CONCLUSIONS
  Emodin markedly reversed OXA resistance by enhancing OXA DNA damage in HepG2/OXA cells, and the molecular mechanism was related to the inhibitory effect on ERCC1 expression being mediated by the FGFR2/ERK1/2 signaling pathway.
authors.affiliation: Integration Traditional Chinese Medicine and Western Medicine Department, TongJi Hospital, Huazhong University of Science and Technology, Wuhan 430030, Hubei Province, China.
authors.forename: Gang
authors.initials: G
authors.lastname: Chen
authors.forename: Hong
authors.initials: H
authors.lastname: Qiu
authors.forename: Shan-Dong
authors.initials: SD
authors.lastname: Ke
authors.forename: Shao-Ming
authors.initials: SM
authors.lastname: Hu
authors.forename: Shi-Ying
authors.initials: SY
authors.lastname: Yu
authors.forename: Sheng-Quan
authors.initials: SQ
authors.lastname: Zou
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D006528:Carcinoma, Hepatocellular / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D049109:Cell Proliferation / Q000187:drug effects; D004249:DNA Damage; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D019008:Drug Resistance, Neoplasm / Q000187:drug effects*; D004642:Emodin / Q000494:pharmacology*; D004720:Endonucleases / Q000378:metabolism*; D051523:Fibroblast Growth Factor 7 / Q000378:metabolism; D056945:Hep G2 Cells; D006801:Humans; D020128:Inhibitory Concentration 50; D008113:Liver Neoplasms / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D009944:Organoplatinum Compounds / Q000494:pharmacology*; D000077150:Oxaliplatin; D010766:Phosphorylation; D034622:RNA Interference; D051497:Receptor, Fibroblast Growth Factor, Type 2 / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D014162:Transfection
chemical_list: D000970:Antineoplastic Agents; D004268:DNA-Binding Proteins; D009944:Organoplatinum Compounds; D000077150:Oxaliplatin; D051523:Fibroblast Growth Factor 7; C496353:FGFR2 protein, human; D051497:Receptor, Fibroblast Growth Factor, Type 2; C535150:MAPK1 protein, human; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; C071447:ERCC1 protein, human; D004720:Endonucleases; D004642:Emodin
keywords: Emodin; Excision repair cross-complementation group 1; Extracellular signal-regulated kinase; Fibroblast growth factor receptor 2; Hepatocellular carcinoma; Platinum resistance