title: Pluronic block copolymers alter apoptotic signal transduction of doxorubicin in drug-resistant cancer cells.
abstract: Pluronic block copolymer P85 (P85) sensitizes multidrug resistant (MDR) cancer cells resulting in the increase of cytotoxic activity of antineoplastic agents. This effect is attributed to the inhibition of the most clinically relevant drug efflux transporter, P-glycoprotein (Pgp), through the combined ATP depletion and inhibition of Pgp ATPase activity. The present study elucidates effects of an anticancer agent, doxorubicin (Dox), formulated with P85 on drug-induced apoptosis in MDR cancer cells. Early and late stages of apoptosis were detected by Annexin V and TUNEL methods, respectively. In parallel experiments, the expression of genes related to apoptosis, BCL2, BCLXL, BAX, P53, APAF1, Caspase 3, and Caspase 9, was determined by RT-PCR. The obtained data suggest that Dox/P85 formulation induces apoptosis in the resistant cancer cells more efficiently than free Dox. The treatment of the cells with Dox alone simultaneously activated a proapoptotic signal and an antiapoptotic cellular defense. Therefore, the apoptosis induction by Dox was substantially limited. In contrast, the treatment of the cells with Dox/P85 formulation significantly enhanced the proapoptotic activity of the drug and prevented the activation of the antiapoptotic cellular defense. This is likely to result in the stronger cytotoxic response of the resistant cells to the Dox/P85 formulation compared to the free drug.
authors.affiliation: Department of Pharmaceutics, Rutgers, The State University of New Jersey, 160 Frelinghuysen Road, Piscataway, NJ 08854, USA.
authors.forename: Tamara
authors.initials: T
authors.lastname: Minko
authors.forename: Elena V
authors.initials: EV
authors.lastname: Batrakova
authors.forename: Shu
authors.initials: S
authors.lastname: Li
authors.forename: Yili
authors.initials: Y
authors.lastname: Li
authors.forename: Refika I
authors.initials: RI
authors.lastname: Pakunlu
authors.forename: Valery Yu
authors.initials: VY
authors.lastname: Alakhov
authors.forename: Alexander V
authors.initials: AV
authors.lastname: Kabanov
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism; D017304:Annexin A5 / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects* / Q000235:genetics; D001943:Breast Neoplasms / Q000378:metabolism; D045744:Cell Line, Tumor; D004317:Doxorubicin / Q000494:pharmacology*; D019008:Drug Resistance, Neoplasm; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000378:metabolism; D005079:Excipients / Q000494:pharmacology*; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D019450:Genes, MDR; D006801:Humans; D020287:In Situ Nick-End Labeling; D007624:KB Cells; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D020442:Poloxamer / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects*; D012996:Solutions
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D017304:Annexin A5; D000970:Antineoplastic Agents; D004791:Enzyme Inhibitors; D005079:Excipients; D012996:Solutions; D020442:Poloxamer; D004317:Doxorubicin