title: Synergistic action of doxorubicin and sulindac in human cervix carcinoma cells - studies on possible mechanisms.
abstract: BACKGROUND
  Epidemiologic and experimental studies have shown that cyclooxygenase-2 (COX-2) inhibitors as non-steroidal anti-inflammatory drugs (NSAIDs) are effective chemopreventive agents. The mechanisms underlying the antitumor activity of COX-2 inhibitors are thought to involve inhibition of COX-2 enzyme activity and induction of apoptosis. The aim of the current work was to study the mechanisms of synergistic action noted in HeLa cervical carcinoma cells under doxorubicin (DOX) and sulindac (SUL) co-treatment.
  
  
  METHODS
  Cytotoxic activity of the drugs was defined with MTT test, apoptosis was detected with TUNEL test, DOX transmembrane efflux was measured fluorometrically, expression of MDR-1 and MRP-1 was determined with quantitative real time - PCR (QRT-PCR).
  
  
  RESULTS
  It was shown that SUL at non-toxic concentrations, 10 and 50 microM, is an effective enhancer of cytotoxic action for DOX in 0.5 and 1 microM, respectively; however, only for SUL concentration equal to 50 microM potentiated apoptosis induced by 1 microM of DOX. Moreover, blocking DOX efflux outside the cells was observed. The QRT - PCR analysis has shown that, when used simultaneously, DOX 1 microM and SUL 50 microM results in decreased mRNA level for MDR-1 and MRP-1.
  
  
  CONCLUSIONS
  It is concluded that cytotoxic action of DOX against HeLa cells is enhanced by non-toxic concentrations of SUL. The observed effect is due to quenching of MDR-1 and MRP-1 genes expression, which results in blocking of efflux of DOX outside the cells, which in turn correlates with enhanced apoptotic effects. According to obtained results the mechanisms of potentiating of DOX action by SUL are dose specific.
authors.affiliation: Department of Biochemistry and Biopharmaceuticals, National Medicines Institute, Warsaw, Poland. b-gruber@il.waw.pl
authors.forename: Beata Maria
authors.initials: BM
authors.lastname: Gruber
authors.forename: Irena
authors.initials: I
authors.lastname: Bubko
authors.forename: Jolanta
authors.initials: J
authors.lastname: Krzyszton-Russjan
authors.forename: Elzbieta Lidia
authors.initials: EL
authors.lastname: Anuszewska
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology* / Q000627:therapeutic use; D017931:DNA Primers / Q000235:genetics; D004305:Dose-Response Relationship, Drug; D004317:Doxorubicin / Q000494:pharmacology* / Q000627:therapeutic use; D004357:Drug Synergism; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D006367:HeLa Cells; D006801:Humans; D020287:In Situ Nick-End Labeling; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013467:Sulindac / Q000494:pharmacology* / Q000627:therapeutic use; D013778:Tetrazolium Salts; D013844:Thiazoles; D002583:Uterine Cervical Neoplasms / Q000188:drug therapy*
chemical_list: D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D016861:Cyclooxygenase Inhibitors; D017931:DNA Primers; D004317:Doxorubicin; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D013467:Sulindac; D013778:Tetrazolium Salts; D013844:Thiazoles; C513055:ABCB1 protein, human; C022616:thiazolyl blue; C421109:multidrug resistance-associated protein 1