title: Zinc protoporphyrin IX enhances chemotherapeutic response of hepatoma cells to cisplatin.
abstract: OBJECTIVE
  To investigate the effect of zinc protoporphyrin IX on the response of hepatoma cells to cisplatin and the possible mechanism involved.
  
  
  METHODS
  Cytotoxicity was determined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Apoptosis was determined by a flow cytometric assay. Western blotting was used to measure protein expression. Heme oxygenase (HO)-1 activity was measured by determining the level of bilirubin generated in isolated microsomes. Reactive oxygen species (ROS) production was monitored by flow cytometry. Caspase-3 activity was measured with a colorimetric assay kit. Mice were inoculated with 1 × 10(7) tumor cells subcutaneously into the right flanks. All mice were sacrificed 6 wk after the first treatment and tumors were weighed and measured.
  
  
  RESULTS
  Overexpression of HO-1 in HepG2 cell line was associated with increased chemoresistance to cis-diaminedichloroplatinum (cisplatin; CDDP) compared to other cell lines in vitro. Inhibition of HO-1 expression or activity by zinc protoporphyrin IX (ZnPP IX) markedly augmented CDDP-mediated cytotoxicity towards all liver cancer cell lines in vitro and in vivo. In contrast, induction of HO-1 with hemin increased resistance of tumor cells to CDDP-mediated cytotoxicity in vitro and in vivo. Furthermore, cells treated with ZnPP IX plus CDDP exhibited marked production of intracellular ROS and caspase-3 activity, which paralleled the incidence of cell apoptosis, whereas hemin decreased cellular ROS and caspase-3 activity induced by CDDP.
  
  
  CONCLUSIONS
  ZnPP IX increases cellular sensitivity and susceptibility of liver cancer cell lines to CDDP and this may represent a mechanism of increasing ROS.
authors.affiliation: Yang-Sui Liu, Huan-Song Li, Dun-Feng Qi, Jun Zhang, Xin-Chun Jiang, Kui Shi, Xiao-Jun Zhang, Xin-Hui Zhang, The Central Hospital of Xuzhou City, Xuzhou Hospital Affiliated to Medical College of Southeast University, Xuzhou 221009, Jiangsu Province, China.
authors.forename: Yang-Sui
authors.initials: YS
authors.lastname: Liu
authors.affiliation: Yang-Sui Liu, Huan-Song Li, Dun-Feng Qi, Jun Zhang, Xin-Chun Jiang, Kui Shi, Xiao-Jun Zhang, Xin-Hui Zhang, The Central Hospital of Xuzhou City, Xuzhou Hospital Affiliated to Medical College of Southeast University, Xuzhou 221009, Jiangsu Province, China.
authors.forename: Huan-Song
authors.initials: HS
authors.lastname: Li
authors.affiliation: Yang-Sui Liu, Huan-Song Li, Dun-Feng Qi, Jun Zhang, Xin-Chun Jiang, Kui Shi, Xiao-Jun Zhang, Xin-Hui Zhang, The Central Hospital of Xuzhou City, Xuzhou Hospital Affiliated to Medical College of Southeast University, Xuzhou 221009, Jiangsu Province, China.
authors.forename: Dun-Feng
authors.initials: DF
authors.lastname: Qi
authors.affiliation: Yang-Sui Liu, Huan-Song Li, Dun-Feng Qi, Jun Zhang, Xin-Chun Jiang, Kui Shi, Xiao-Jun Zhang, Xin-Hui Zhang, The Central Hospital of Xuzhou City, Xuzhou Hospital Affiliated to Medical College of Southeast University, Xuzhou 221009, Jiangsu Province, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Yang-Sui Liu, Huan-Song Li, Dun-Feng Qi, Jun Zhang, Xin-Chun Jiang, Kui Shi, Xiao-Jun Zhang, Xin-Hui Zhang, The Central Hospital of Xuzhou City, Xuzhou Hospital Affiliated to Medical College of Southeast University, Xuzhou 221009, Jiangsu Province, China.
authors.forename: Xin-Chun
authors.initials: XC
authors.lastname: Jiang
authors.affiliation: Yang-Sui Liu, Huan-Song Li, Dun-Feng Qi, Jun Zhang, Xin-Chun Jiang, Kui Shi, Xiao-Jun Zhang, Xin-Hui Zhang, The Central Hospital of Xuzhou City, Xuzhou Hospital Affiliated to Medical College of Southeast University, Xuzhou 221009, Jiangsu Province, China.
authors.forename: Kui
authors.initials: K
authors.lastname: Shi
authors.affiliation: Yang-Sui Liu, Huan-Song Li, Dun-Feng Qi, Jun Zhang, Xin-Chun Jiang, Kui Shi, Xiao-Jun Zhang, Xin-Hui Zhang, The Central Hospital of Xuzhou City, Xuzhou Hospital Affiliated to Medical College of Southeast University, Xuzhou 221009, Jiangsu Province, China.
authors.forename: Xiao-Jun
authors.initials: XJ
authors.lastname: Zhang
authors.affiliation: Yang-Sui Liu, Huan-Song Li, Dun-Feng Qi, Jun Zhang, Xin-Chun Jiang, Kui Shi, Xiao-Jun Zhang, Xin-Hui Zhang, The Central Hospital of Xuzhou City, Xuzhou Hospital Affiliated to Medical College of Southeast University, Xuzhou 221009, Jiangsu Province, China.
authors.forename: Xin-Hui
authors.initials: XH
authors.lastname: Zhang
mesh_terms: D000818:Animals; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D006528:Carcinoma, Hepatocellular / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D053148:Caspase 3 / Q000378:metabolism; D002945:Cisplatin / Q000008:administration & dosage; D004305:Dose-Response Relationship, Drug; D019008:Drug Resistance, Neoplasm; D005260:Female; D051547:Heme Oxygenase-1 / Q000378:metabolism; D006427:Hemin / Q000494:pharmacology; D056945:Hep G2 Cells; D006801:Humans; D008113:Liver Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D008819:Mice, Nude; D018384:Oxidative Stress / Q000187:drug effects; D011524:Protoporphyrins / Q000008:administration & dosage; D017382:Reactive Oxygen Species / Q000378:metabolism; D013997:Time Factors; D047368:Tumor Burden / Q000187:drug effects; D023041:Xenograft Model Antitumor Assays
chemical_list: D011524:Protoporphyrins; D017382:Reactive Oxygen Species; C017803:zinc protoporphyrin; D006427:Hemin; C496541:HMOX1 protein, human; D051547:Heme Oxygenase-1; C505407:CASP3 protein, human; D053148:Caspase 3; D002945:Cisplatin
keywords: Chemotherapy; Cisplatin; Heme oxygenase-1; Liver cancer cell lines; Zinc protoporphyrin IX