title: Induction of a multifactorial resistance phenotype by high paclitaxel selective pressure in a human ovarian carcinoma cell line.
abstract: Paclitaxel (PTX) is a potent anti-neoplastic agent that is highly effective in treating ovarian cancer. Nevertheless, the emergence of PTX resistance has limited the control of this disease. To gain insight into the molecular alterations accompanying drug resistance in ovarian cancer, we generated a new stable PTX-resistant ovarian carcinoma cell line. CABA I cells, which display an intrinsic PTX resistance (IC50 = 800 ng/ml), were subjected to continuous exposure to PTX. From the residual surviving cells, the highly PTX-resistant line CABA-PTX (IC50 = 256000 ng/ml) was generated and stably maintained in vitro. Analysis of beta-tubulin expression indicated that only the HM40 and Hbeta9 isotypes were expressed in both parental and resistant cells. No specific point mutations in the HM40 were detected in either cell line, but expression levels of this isotype were significantly reduced (40%) in CABA-PTX cells. Hbeta9 levels were unchanged. In those cells, PTX resistance was associated with cross-resistance to vinblastine but not to methotrexate or 5-fluorouracil. Verapamil treatment did not reverse the intrinsic drug resistance of parental cells, but partially modulated the sensitivity of CABA-PTX cells to PTX and induced total sensitivity to vinblastine. No changes in the cell surface expression of the drug efflux pumps MRP1, MRP2 and P-glycoprotein were observed. PTX influx, monitored using a fluorescent drug derivative, was significantly reduced and delayed in CABA-PTX cells as compared to the parental cells. Together, these findings suggest that more than one mechanism is involved in PTX resistance, making CABA-PTX cell line a potentially valuable in vitro tool to study multifactorial acquired drug resistance in ovarian cancer.
authors.affiliation: Dipartimento di Medicina Sperimentale, Università di L'Aquila, L'Aquila, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Violini
authors.forename: S
authors.initials: S
authors.lastname: D'Ascenzo
authors.lastname: Bagnoli M
authors.forename: D
authors.initials: D
authors.lastname: Millimaggi
authors.forename: S
authors.initials: S
authors.lastname: Miotti
authors.forename: S
authors.initials: S
authors.lastname: Canevari
authors.forename: A
authors.initials: A
authors.lastname: Pavan
authors.forename: V
authors.initials: V
authors.lastname: Dolo
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology; D002455:Cell Division; D045744:Cell Line, Tumor; D004305:Dose-Response Relationship, Drug; D019008:Drug Resistance, Neoplasm; D005260:Female; D005434:Flow Cytometry; D005472:Fluorouracil / Q000494:pharmacology; D006801:Humans; D020128:Inhibitory Concentration 50; D008727:Methotrexate / Q000494:pharmacology; D024101:Mitochondrial Proteins / Q000378:metabolism; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000378:metabolism; D010051:Ovarian Neoplasms / Q000188:drug therapy*; D017239:Paclitaxel / Q000494:pharmacology*; D010641:Phenotype; D012269:Ribosomal Proteins / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D013778:Tetrazolium Salts / Q000494:pharmacology; D013997:Time Factors; D014404:Tubulin / Q000378:metabolism; D014700:Verapamil / Q000494:pharmacology; D014747:Vinblastine / Q000494:pharmacology
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000972:Antineoplastic Agents, Phytogenic; D005472:Fluorouracil; D008727:Methotrexate; D024101:Mitochondrial Proteins; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D017239:Paclitaxel; D012269:Ribosomal Proteins; D029701:Saccharomyces cerevisiae Proteins; D013778:Tetrazolium Salts; D014404:Tubulin; D014700:Verapamil; D014747:Vinblastine; C093947:MRP2 protein, S cerevisiae; C059087:2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-((phenylamino)carbonyl)-2H-tetrazolium hydroxide; C421109:multidrug resistance-associated protein 1