title: Nitric oxide reverts the resistance to doxorubicin in human colon cancer cells by inhibiting the drug efflux.
abstract: Multidrug resistance (MDR) is a phenomenon by which cancer cells evade the cytotoxic effects of chemotherapeutic agents. It may occur through different mechanisms, but it often correlates with the overexpression of integral membrane transporters, such as P-glycoprotein (Pgp) and MDR-associated proteins (MRPs), with resulting decrease of drug accumulation and cellular death. Doxorubicin is a substrate of Pgp; it has been suggested that its ability to induce synthesis of nitric oxide (NO) could explain, at least in part, its cytotoxic effects. Culturing the human epithelial colon cell line HT29 in the presence of doxorubicin, we obtained a doxorubicin-resistant (HT29-dx) cell population: these cells accumulated less intracellular doxorubicin, were less sensitive to the cytotoxic effects of doxorubicin and cisplatin, overexpressed Pgp and MRP3, and exhibited a lower NO production (both under basal conditions and after doxorubicin stimulation). The resistance to doxorubicin could be reversed when HT29-dx cells were incubated with inducers of NO synthesis (cytokines mix, atorvastatin). Some NO donors increased the drug accumulation in HT29-dx cells in a guarosine-3':5'-cyclic monophosphate-independent way; this effect was associated with a marked reduction of doxorubicin efflux rate in HT29 and HT29-dx cells, and tyrosine nitration in the MRP3 protein. Our results suggest that onset of MDR and impairment of NO synthesis are related; this finding could point to a new strategy to reverse doxorubicin resistance in human cancer.
authors.affiliation: Department of Genetics, Biology and Biochemistry, University of Torino, and Research Center on Experimental Medicine, Via Santena 5/bis, Turin, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Riganti
authors.forename: Erica
authors.initials: E
authors.lastname: Miraglia
authors.forename: Daniele
authors.initials: D
authors.lastname: Viarisio
authors.forename: Costanzo
authors.initials: C
authors.lastname: Costamagna
authors.forename: Gianpiero
authors.initials: G
authors.lastname: Pescarmona
authors.forename: Dario
authors.initials: D
authors.lastname: Ghigo
authors.forename: Amalia
authors.initials: A
authors.lastname: Bosia
mesh_terms: D000903:Antibiotics, Antineoplastic / Q000493:pharmacokinetics / Q000494:pharmacology*; D003110:Colonic Neoplasms / Q000188:drug therapy* / Q000378:metabolism*; D006152:Cyclic GMP / Q000378:metabolism; D004317:Doxorubicin / Q000493:pharmacokinetics / Q000494:pharmacology*; D018432:Drug Resistance, Multiple; D019008:Drug Resistance, Neoplasm; D019073:HT29 Cells; D006801:Humans; D007527:Isoenzymes; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000378:metabolism; D009566:Nitrates / Q000378:metabolism; D009569:Nitric Oxide / Q000096:biosynthesis / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D026423:S-Nitroso-N-Acetylpenicillamine / Q000494:pharmacology
chemical_list: D000903:Antibiotics, Antineoplastic; D006152:Cyclic GMP; D004317:Doxorubicin; D007527:Isoenzymes; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D009566:Nitrates; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D026423:S-Nitroso-N-Acetylpenicillamine; C114462:multidrug resistance-associated protein 3