title: Microparticles and their emerging role in cancer multidrug resistance.
abstract: Drug resistance is a major obstacle to the successful treatment of cancer as tumor cells either fail to reduce in size following chemotherapy or the cancer recurs after an initial response. The phenomenon of multidrug resistance (MDR) is particularly problematic as it involves the simultaneous resistance to numerous chemotherapeutics of different classes. MDR is predominantly attributed to the overexpression of efflux transporters such as P-glycoprotein (P-gp) and the Multidrug Resistance-Associated Protein 1 (MRP1). P-gp and MRP1 are members of the ATP Binding Cassette (ABC) superfamily of transporters and are capable of effluxing many chemotherapeutics out of cancer cells, allowing them to survive the toxic insult. Numerous strategies have been developed over the years to circumvent MDR. Of these, the discovery and implementation of P-gp and MRP1 inhibitors have been most extensively studied. However, these inhibitors have not been able to be used clinically. While research continues in this area, it must also be acknowledged that other avenues must be explored. Recently, the novel 'non-genetic' acquisition of P-gp-mediated MDR by microparticles (MPs) has been reported. MPs are vesicles 0.1-1μm in diameter that are released via plasma membrane blebbing. They are important mediators of inflammation, coagulation and vascular homeostasis. In addition to surface P-gp protein, MPs also carry various nucleic acid species as cargo. This 'non-genetic' intercellular transfer provides an alternative pathway for the cellular acquisition and dissemination of traits and implicates MPs as important mediators in the spread of MDR and provides a novel pathway for the circumvention of MDR.
authors.affiliation: Vascular Immunology Unit, Faculty of Medicine, The University of Sydney, Medical Foundation Building (K25), Room 208, 92-94 Parramatta Rd., Camperdown, NSW 2042, Australia. jgon7696@uni.sydney.edu.au
authors.forename: J
authors.initials: J
authors.lastname: Gong
authors.forename: R
authors.initials: R
authors.lastname: Jaiswal
authors.forename: J-M
authors.initials: JM
authors.lastname: Mathys
authors.forename: V
authors.initials: V
authors.lastname: Combes
authors.forename: G E R
authors.initials: GE
authors.lastname: Grau
authors.forename: M
authors.initials: M
authors.lastname: Bebawy
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D018528:ATP-Binding Cassette Transporters / Q000378:metabolism; D000970:Antineoplastic Agents / Q000494:pharmacology / Q000633:toxicity; D055252:Cell-Derived Microparticles / Q000502:physiology*; D018432:Drug Resistance, Multiple; D019008:Drug Resistance, Neoplasm; D006801:Humans; D035683:MicroRNAs; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D018528:ATP-Binding Cassette Transporters; D000970:Antineoplastic Agents; D035683:MicroRNAs; D027425:ATP-Binding Cassette, Sub-Family C Proteins; C421109:multidrug resistance-associated protein 1