title: KSP inhibitor ARRY-520 as a substitute for Paclitaxel in Type I ovarian cancer cells.
abstract: BACKGROUND
  We previously described a sub-population of epithelial ovarian cancer (EOC) cells with a functional TLR-4/MyD88/NF-kappaB pathway (Type I EOC cells), which confers the capacity to respond to Paclitaxel, a known TLR-4 ligand, by enhancing NF-kappaB activity and upregulating cytokine secretion - events that are known to promote tumor progression. It is therefore important to distinguish those patients that should not receive Paclitaxel; it is also important to identify alternative chemotherapy options that would benefit this sub-group of patients. The objective of this study is to determine if the KSP inhibitor, ARRY-520, can be a substitute for Paclitaxel in patients with Type I EOC.
  
  
  METHODS
  EOC cells isolated from either ascites or tumor tissue were treated with increasing concentrations of ARRY-520 or Paclitaxel and cell viability determined. Activation of the apoptotic pathway was determined using Western blot analysis. Mitochondrial integrity was quantified using JC1 dye. Cytokine profiling was performed from supernatants using xMAP technology. NF-kappaB activity was measured using a Luciferase reporter system. In vivo activity was determined using a subcutaneous xenograft mouse model.
  
  
  RESULTS
  ARRY-520 and Paclitaxel exhibited the same cytotoxic effect on Type I and II cells. The GI50 at 48 h for Type II EOC cells was 0.0015 microM and 0.2 microM for ARRY-520 and Paclitaxel, respectively. For Type I EOC cells, the GI50 at 48 h was > 3 microM and >20 microM for ARRY-520 and Paclitaxel, respectively. Decrease in the number of viable cells was accompanied by mitochondrial depolarization and caspase activation. Unlike Paclitaxel, ARRY-520 did not induce NF-kappaB activation, did not enhance cytokine secretion, nor induce ERK phosphorylation in Type I EOC cells.
  
  
  CONCLUSIONS
  Administration of Paclitaxel to patients with high percentage Type I cancer cells could have detrimental effects due to Paclitaxel-induced enhancement of NF-kappaB and ERK activities, and cytokine production (e.g. IL-6), which promote chemoresistance and tumor progression. ARRY-520 has similar anti-tumor activity in EOC cells as that of Paclitaxel. However, unlike Paclitaxel, it does not induce these pro-tumor effects in Type I cells. Therefore, the KSP inhibitor ARRY-520 may represent an alternative to Paclitaxel in this subgroup of EOC patients.
authors.affiliation: Department of Obstetrics, Gynecology and Reproductive Sciences, Yale University School of Medicine, New Haven, CT, USA. ghkim@pusan.ac.kr
authors.forename: Ki Hyung
authors.initials: KH
authors.lastname: Kim
authors.forename: Yanhua
authors.initials: Y
authors.lastname: Xie
authors.forename: Ewan M
authors.initials: EM
authors.lastname: Tytler
authors.forename: Richard
authors.initials: R
authors.lastname: Woessner
authors.forename: Gil
authors.initials: G
authors.lastname: Mor
authors.forename: Ayesha B
authors.initials: AB
authors.lastname: Alvero
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000627:therapeutic use*; D017209:Apoptosis / Q000187:drug effects; D001201:Ascites / Q000473:pathology; D053148:Caspase 3 / Q000032:analysis / Q000378:metabolism; D053179:Caspase 7 / Q000032:analysis / Q000378:metabolism; D053453:Caspase 9 / Q000032:analysis / Q000378:metabolism; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D017930:Genes, Reporter; D006801:Humans; D020128:Inhibitory Concentration 50; D016547:Kinesins / Q000037:antagonists & inhibitors*; D008156:Luciferases / Q000378:metabolism; D009924:Organ Culture Techniques; D010051:Ovarian Neoplasms / Q000188:drug therapy* / Q000473:pathology*; D017239:Paclitaxel / Q000627:therapeutic use*; D013830:Thiadiazoles / Q000037:antagonists & inhibitors; D013997:Time Factors; D014162:Transfection
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D004791:Enzyme Inhibitors; C470243:KIF11 protein, human; D013830:Thiadiazoles; C544550:filanesib; D008156:Luciferases; D053148:Caspase 3; D053179:Caspase 7; D053453:Caspase 9; D016547:Kinesins; D017239:Paclitaxel