title: Correlation between decreased apoptosis and multidrug resistance (MDR) in murine leukemic T cell lines.
abstract: Cancer cells may frequently develop cross-resistance to structurally dissimilar chemotherapeutic agents. However, the molecular mechanisms for sensitivity and resistance of tumor cells towards chemotherapy are still partially understood. Antineoplasic drugs have been shown to induce apoptosis in chemosensitive leukemias and solid tumors. In this work, cross-resistance among vincristine (VCR), doxorubicin (DOX) and other antineoplasic agents commonly used in the treatment of leukemia such as etoposide (VP-16), methotrexate (MTX), cyclophosphamide (CTX), dexamethasone (DEX), cytarabine (Ara-C) and L-asparaginase on vincristine resistant (LBR-V160), doxorubicin resistant (LBR-D160) and sensitive (LBR-) murine leukemic T cell lines, was determined. The effect of antineoplasic agents was assayed by tritiated thymidine incorporation. Our results showed that VCR exhibited cross-resistance with DOX, VP-16, DEX and MTX, while DOX demonstrated cross-resistance with VCR, VP-16 and MTX. Ara-C failed to present cross-resistance with any cell line. Apoptosis induced by the above drugs on the same cell lines was analyzed by acridine orange and ethidium bromide staining, DNA hypoploidy (flow cytometry) and oligonucleosomal fragmentation of nuclear DNA showing that therapeutic concentrations of these chemotherapeutic agents induced apoptosis in the LBR- cell line. Our results demonstrated that, except for DEX, none of the drugs presenting cross-resistance were able to induce cell death on LBR-V 160 or LBR-D 160 cell lines.
authors.affiliation: Catedra de Inmunología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires (UBA), IDEHU-CONICET, Argentina. meclopes@hotmail.com
authors.forename: E C
authors.initials: EC
authors.lastname: Lopes
authors.forename: M G
authors.initials: MG
authors.lastname: García
authors.forename: L
authors.initials: L
authors.lastname: Vellón
authors.forename: E
authors.initials: E
authors.lastname: Alvarez
authors.forename: S E
authors.initials: SE
authors.lastname: Hajos
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004317:Doxorubicin / Q000494:pharmacology; D018432:Drug Resistance, Multiple; D005047:Etoposide / Q000494:pharmacology; D015458:Leukemia, T-Cell / Q000473:pathology*; D008727:Methotrexate / Q000494:pharmacology; D051379:Mice; D014407:Tumor Cells, Cultured / Q000187:drug effects*; D014750:Vincristine / Q000494:pharmacology
chemical_list: D000970:Antineoplastic Agents; D014750:Vincristine; D005047:Etoposide; D004317:Doxorubicin; D008727:Methotrexate