title: Molecular determinants of intrinsic resistance to doxorubicin in human cancer cell lines.
abstract: Intrinsic or acquired drug resistance poses a major challenge to the success of chemotherapy in the clinical management of human cancers. While acquired multidrug resistance (MDR), whereby cells become refractory to multiple drugs, has been extensively investigated, the mechanistic basis for intrinsic resistance remains elusive, so that this condition is largely unmanageable in the clinical setting. To address this issue, we have assessed the effects of the anticancer agent doxorubicin (DX) on a panel of human tumor cell lines originally derived from untreated patients and tried to establish a correlation between cell response and a number of parameters, including drug accumulation and/or drug efflux; differences in expression and/or subcellular distribution of proteins involved in the apoptotic process (e.g., p53, Bcl-2, Bax) and intracellular signal transducers (PKCalpha); changes in key detoxification processes. Based on our results, 'classic' multispecific drug transporters (P-glycoprotein, MDR-related proteins) only seem to play a minor role in the intrinsically resistant phenotype, whereas LRP may contribute to resistance in non-small cell lung carcinoma (NSCLC) cells. No relationship was observed between drug response and expression and/or subcellular localization of apoptosis-related proteins; however, increased PKCalpha levels are associated with poor drug response, suggesting that one or more substrates of this enzyme may be relevant to the resistant phenotype. Finally, overactive glutathione-recycling pathways may contribute to DX resistance.
authors.affiliation: DBSF, University of Insubria, I-21052 Busto Arsizio (VA), Italy.
authors.forename: Marzia B
authors.initials: MB
authors.lastname: Gariboldi
authors.forename: Raffaella
authors.initials: R
authors.lastname: Ravizza
authors.forename: Loredana
authors.initials: L
authors.lastname: Riganti
authors.forename: Stefania
authors.initials: S
authors.lastname: Meschini
authors.forename: Annarica
authors.initials: A
authors.lastname: Calcabrini
authors.forename: Manuela
authors.initials: M
authors.lastname: Marra
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Arancia
authors.forename: Ersilia
authors.initials: E
authors.lastname: Dolfini
authors.forename: Elena
authors.initials: E
authors.lastname: Monti
mesh_terms: D000970:Antineoplastic Agents / Q000493:pharmacokinetics* / Q000633:toxicity*; D017209:Apoptosis / Q000187:drug effects; D001692:Biological Transport; D004305:Dose-Response Relationship, Drug; D004317:Doxorubicin / Q000493:pharmacokinetics* / Q000633:toxicity*; D018432:Drug Resistance, Multiple; D019008:Drug Resistance, Neoplasm; D006801:Humans; D014407:Tumor Cells, Cultured
chemical_list: D000970:Antineoplastic Agents; D004317:Doxorubicin