title: NCX-4040, a nitric oxide-releasing aspirin, sensitizes drug-resistant human ovarian xenograft tumors to cisplatin by depletion of cellular thiols.
abstract: BACKGROUND
  Ovarian carcinoma is the leading cause of mortality among gynecological cancers in the world. The high mortality rate is associated with lack of early diagnosis and development of drug resistance. The antitumor efficacy and mechanism of NCX-4040, a nitric oxide-releasing aspirin derivative, against ovarian cancer is studied.
  
  
  METHODS
  NCX-4040, alone or in combination with cisplatin (cis-diamminedichloroplatinum, cDDP), was studied in cisplatin-sensitive (A2780 WT) and cisplatin-resistant (A2780 cDDP) cell lines as well as xenograft tumors grown in nude mice. Electron paramagnetic resonance (EPR) was used for measurements of nitric oxide and redox state. Immunoblotting analysis of A2780 cDDP tumor xenografts from mice was used for mechanistic studies.
  
  
  RESULTS
  Cells treated with NCX-4040 (25 microM) showed a significant reduction of cell viability (A2780 WT, 34.9 +/- 8.7%; A2780 cDDP, 41.7 +/- 7.6%; p < 0.05). Further, NCX-4040 significantly enhanced the sensitivity of A2780 cDDP cells (cisplatin alone, 80.6 +/- 11.8% versus NCX-4040+cisplatin, 26.4 +/- 7.6%; p < 0.01) and xenograft tumors (cisplatin alone, 74.0 +/- 4.4% versus NCX-4040+cisplatin, 56.4 +/- 7.8%; p < 0.05), to cisplatin treatment. EPR imaging of tissue redox and thiol measurements showed a 5.5-fold reduction (p < 0.01) of glutathione in NCX-4040-treated A2780 cDDP tumors when compared to untreated controls. Immunoblotting analysis of A2780 cDDP tumor xenografts from mice treated with NCX-4040 and cisplatin revealed significant downregulation of pEGFR (Tyr845 and Tyr992) and pSTAT3 (Tyr705 and Ser727) expression.
  
  
  CONCLUSIONS
  The results suggested that NCX-4040 could resensitize drug-resistant ovarian cancer cells to cisplatin possibly by depletion of cellular thiols. Thus NCX-4040 appears to be a potential therapeutic agent for the treatment of human ovarian carcinoma and cisplatin-resistant malignancies.
authors.affiliation: Center for Biomedical EPR Spectroscopy and Imaging, Davis Heart and Lung Research Institute, Department of Internal Medicine, The Ohio State University, Columbus, OH 43210, USA. kuppusamy.1@osu.edu
authors.forename: Anna
authors.initials: A
authors.lastname: Bratasz
authors.forename: Karuppaiyah
authors.initials: K
authors.lastname: Selvendiran
authors.forename: Tomasz
authors.initials: T
authors.lastname: Wasowicz
authors.forename: Andrey
authors.initials: A
authors.lastname: Bobko
authors.forename: Valery V
authors.initials: VV
authors.lastname: Khramtsov
authors.forename: Louis J
authors.initials: LJ
authors.lastname: Ignarro
authors.forename: Periannan
authors.initials: P
authors.lastname: Kuppusamy
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology* / Q000627:therapeutic use; D001241:Aspirin / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology / Q000627:therapeutic use; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D002945:Cisplatin / Q000494:pharmacology* / Q000627:therapeutic use; D004305:Dose-Response Relationship, Drug; D019008:Drug Resistance, Neoplasm / Q000187:drug effects / Q000502:physiology; D004357:Drug Synergism; D005260:Female; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D015394:Molecular Structure; D009574:Nitro Compounds / Q000737:chemistry / Q000494:pharmacology* / Q000627:therapeutic use; D010051:Ovarian Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D012680:Sensitivity and Specificity; D013223:Statistics as Topic; D013438:Sulfhydryl Compounds / Q000032:analysis / Q000378:metabolism*; D023041:Xenograft Model Antitumor Assays
chemical_list: D000970:Antineoplastic Agents; C498045:NCX 4040; D009574:Nitro Compounds; D013438:Sulfhydryl Compounds; C102148:nitroaspirin; D002945:Cisplatin; D001241:Aspirin