title: Defective hCNT1 transport contributes to gemcitabine chemoresistance in ovarian cancer subtypes: overcoming transport defects using a nanoparticle approach.
abstract: Nucleoside analogs are used as chemotherapeutic options for the treatment of platinum-resistant ovarian cancers. Human concentrative nucleoside transporter 1 (hCNT1) is implicated in sensitizing solid tumors to nucleoside analogs although its role in determining drug efficacy in ovarian cancers remains unclear. Here we examined the functional expression of hCNT1 and compared its contributions toward gemcitabine efficacy in histological subtypes of ovarian cancer. Radioactivity analysis identified hCNT1-mediated (3)H-gemcitabine transport in ovarian cancer cells to be significantly reduced compared with that of normal ovarian surface epithelial cells. Biochemical and immunocytochemical analysis identified that unlike normal ovarian cells which expressed high levels of hCNT1 at the apical cell surface, the transporter was either diminished in expression and/or mislocalized in cell lines of various subtypes of ovarian cancer. Retroviral expression of hCNT1 selectively rescued gemcitabine transport in cell lines representing serous, teratocarcinoma, and endometrioid subtypes, but not clear cell carcinoma (CCC). In addition, exogenous hCNT1 predominantly accumulated in intracytoplasmic vesicles in CCC suggesting defective cellular trafficking of hCNT1 as a contributing factor to transport deficiency. Despite diminution of hCNT1 transport in the majority of ovarian cancers and apparent trafficking defects with CCC, the chemotherapeutic efficacy of gemcitabine was broadly enhanced in all subtypes when delivered via engineered nanoparticles (NPs). Additionally, by bypassing the transport requirement, the delivery of a gemcitabine-cisplatin combination in NP formulation increased their synergistic interactions. These findings uncover hCNT1 as a putative determinant for nucleoside analog chemoresistance in ovarian cancer and may help rationalize drug selection and delivery strategies for various histological subtypes of ovarian cancer.
authors.affiliation: Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, GA, USA.
authors.forename: Sau Wai
authors.initials: SW
authors.lastname: Hung
authors.affiliation: Department of Chemistry, University of Georgia, Athens, GA, USA.
authors.forename: Sean
authors.initials: S
authors.lastname: Marrache
authors.affiliation: Department of Biological Sciences, University of Georgia, Athens, GA, USA.
authors.forename: Shannon
authors.initials: S
authors.lastname: Cummins
authors.affiliation: Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, GA, USA.
authors.forename: Yangzom D
authors.initials: YD
authors.lastname: Bhutia
authors.affiliation: Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, GA, USA.
authors.forename: Hardik
authors.initials: H
authors.lastname: Mody
authors.affiliation: Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, GA, USA.
authors.forename: Shelley B
authors.initials: SB
authors.lastname: Hooks
authors.affiliation: Department of Chemistry, University of Georgia, Athens, GA, USA.
authors.forename: Shanta
authors.initials: S
authors.lastname: Dhar
authors.affiliation: Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, GA, USA. Electronic address: rgovinda@rx.uga.edu.
authors.forename: Rajgopal
authors.initials: R
authors.lastname: Govindarajan
mesh_terms: D000964:Antimetabolites, Antineoplastic / Q000737:chemistry / Q000494:pharmacology*; D001692:Biological Transport; D045744:Cell Line, Tumor; D002945:Cisplatin / Q000737:chemistry / Q000494:pharmacology; D003841:Deoxycytidine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology; D019008:Drug Resistance, Neoplasm; D004357:Drug Synergism; D005260:Female; D006801:Humans; D020128:Inhibitory Concentration 50; D026901:Membrane Transport Proteins / Q000378:metabolism*; D053769:Nanocapsules / Q000737:chemistry; D010051:Ovarian Neoplasms / Q000188:drug therapy / Q000378:metabolism; D000093542:Gemcitabine
chemical_list: D000964:Antimetabolites, Antineoplastic; D026901:Membrane Transport Proteins; D053769:Nanocapsules; C065171:cif nucleoside transporter; D003841:Deoxycytidine; D002945:Cisplatin; D000093542:Gemcitabine
keywords: Chemoresistance; Gemcitabine; Nanoparticles; Nucleoside transporter; Ovarian cancer; hCNT1