title: Purine analogs sensitize the multidrug resistant cell line (NCI-H460/R) to doxorubicin and stimulate the cell growth inhibitory effect of verapamil.
abstract: The resistant cell line NCI-H460/R and its counterpart NCI-H460 were used to investigate the ability of purine analogs to overcome multidrug resistance (MDR) that seriously limit the efficacy of lung cancer regimens with chemotherapeutic agents. Two purine analogs, sulfinosine (SF) and 8-Cl-cAMP, exerted dose-dependent effects on cell growth in both parental and resistant cell lines. They significantly decreased mdr1 expression in NCI-H460/R cells. Low concentrations (1 microM) of SF and 8-Cl-cAMP in combination with doxorubicin (DOX) exerted synergistic growth inhibition in both cell lines. Pretreatment with SF and 8-Cl-cAMP improved the sensitivity to DOX more than verapamil (VER), the standard modulator of MDR. The increased accumulation of DOX observed after the treatment with SF and 8-Cl-cAMP was consistent with the results obtained with VER. VER stimulated the effect of 8-Cl-cAMP on DOX cytotoxicity and mdr1 expression. Combinations of either SF or 8-Cl-cAMP with VER at clinically acceptable concentrations exhibited synergistic effects on cell growth inhibition in the resistant cell line. SF and 8-Cl-cAMP modulated MDR in NCI-H460/R cells, especially when applied before DOX administration. This feature, together with their ability to reverse MDR, renders the purine analogs (in combination with VER) as potential candidates for improving the clinical activity of existing lung cancer therapeutics.
authors.affiliation: Institute for Biological Research, Department of Neurobiology, Laboratory of Molecular Neurobiology, University of Belgrade, Bulevar Despota Stefana 142, 11060, Belgrade, Republic of Serbia.
authors.forename: Milica
authors.initials: M
authors.lastname: Pesić
authors.forename: Ana
authors.initials: A
authors.lastname: Podolski
authors.forename: Ljubisa
authors.initials: L
authors.lastname: Rakić
authors.forename: Sabera
authors.initials: S
authors.lastname: Ruzdijić
mesh_terms: D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000031:analogs & derivatives* / Q000494:pharmacology; D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology; D002121:Calcium Channel Blockers / Q000494:pharmacology; D045744:Cell Line, Tumor; D004305:Dose-Response Relationship, Drug; D004317:Doxorubicin / Q000493:pharmacokinetics / Q000494:pharmacology*; D018432:Drug Resistance, Multiple / Q000187:drug effects*; D019008:Drug Resistance, Neoplasm / Q000187:drug effects*; D004354:Drug Screening Assays, Antitumor; D004357:Drug Synergism; D006131:Growth Inhibitors / Q000494:pharmacology*; D006801:Humans; D011684:Purine Nucleosides / Q000494:pharmacology*; D014700:Verapamil / Q000494:pharmacology*
chemical_list: C513055:ABCB1 protein, human; D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D002121:Calcium Channel Blockers; D006131:Growth Inhibitors; D011684:Purine Nucleosides; C063871:sulfinosine; D015124:8-Bromo Cyclic Adenosine Monophosphate; D004317:Doxorubicin; C044258:8-chloro-cyclic adenosine monophosphate; D014700:Verapamil