calcein-am and Ovarian-Neoplasms

P-glycoprotein belongs to the ATP binding cassette transporters, responsible for the multidrug resistance of cancer cells. These transporters efflux hydrophobic drugs outside cells and decrease their therapeutic efficacy. The aim of this study was to investigate the effect of vandetanib, an oral tyrosine kinase inhibitor of EGFR, VEGFR 2 and RET kinases, on the functionality of P-gp after a 24h-treatment at therapeutic concentration (2μM), and its ability to increase the cytotoxicity of chemotherapeutic agents in multidrug resistance cancer cells. In this study we found that IGROV1-DXR and IGROV1-CDDP cells were resistant to doxorubicin and cisplatin respectively, compare to parental cell line IGROV1. The parental sensitive and the two resistant cell lines similarly expressed MRP1 and did not express BCRP. Moreover, in contrast to the IGROV1 and IGROV1-CDDP cells, IGROV1-DXR cell line overexpressed P-gp. Functional activity studies demonstrated that MRP1 was not functional and the MDR phenotype in IGROV1-DXR cells was linked to P-gp functionality. Results also showed that vandetanib reversed resistance to doxorubicin in IGROV1-DXR cells, but not to cisplatin in IGROV1-CDDP cells. After 24h of treatment, vandetanib increased the accumulation of rhodamine 123 and calcein AM, demonstrating a functional inhibition of the transporter. In IGROV1-DXR cell line, vandetanib reverse resistance to doxorubicin by inhibiting the functionality of P-gp. In conclusion, vandetanib should be an option for drug combination in patients already developing a P-gp mediated multidrug resistance.

Topics: Antibiotics, Antineoplastic; ATP Binding Cassette Transporter, Subfamily B; ATP Binding Cassette Transporter, Subfamily B, Member 1; ATP Binding Cassette Transporter, Subfamily G, Member 2; ATP-Binding Cassette Transporters; Cell Line, Tumor; Cell Proliferation; Cell Survival; Cisplatin; Dose-Response Relationship, Drug; Doxorubicin; Drug Resistance, Neoplasm; Female; Fluoresceins; Fluorescent Dyes; Humans; Multidrug Resistance-Associated Proteins; Neoplasm Proteins; Ovarian Neoplasms; Phenotype; Piperidines; Protein Kinase Inhibitors; Quinazolines; Rhodamine 123; Time Factors

To test the ability of nanoparticle formulations to overcome P-glycoprotein (P-gp)-mediated multidrug resistance, several different doxorubicin and paclitaxel-loaded lipid nanoparticles were prepared. Doxorubicin nanoparticles showed 6- to 8-fold lower IC(50) values in P-gp-overexpressing human cancer cells than those of free doxorubicin. The IC(50) value of paclitaxel nanoparticles was over 9-fold lower than that of Taxol in P-gp-overexpressing cells. A series of in vitro cell assays were used including quantitative studies on uptake and efflux, inhibition of calcein acetoxymethylester efflux, alteration of ATP levels, membrane integrity, mitochondrial membrane potential, apoptosis, and cytotoxicity. Enhanced uptake and prolonged retention of doxorubicin were observed with nanoparticle-based formulations in P-gp-overexpressing cells. Calcein acetoxymethylester and ATP assays confirmed that blank nanoparticles inhibited P-gp and transiently depleted ATP. I.v. injection of pegylated paclitaxel nanoparticles showed marked anticancer efficacy in nude mice bearing resistant NCI/ADR-RES tumors versus all control groups. Nanoparticles may be used to target both drug and biological mechanisms to overcome multidrug resistance via P-gp inhibition and ATP depletion.

Topics: Adenosine Triphosphate; Animals; Apoptosis; ATP Binding Cassette Transporter, Subfamily B, Member 1; Cell Line, Tumor; Doxorubicin; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Drug Screening Assays, Antitumor; Female; Fluoresceins; Humans; Melanoma; Membrane Potential, Mitochondrial; Mice; Mice, Nude; Nanoparticles; Ovarian Neoplasms; Paclitaxel; Xenograft Model Antitumor Assays

Multidrug resistance (MDR) is a major factor which contributes to the failure of cancer chemotherapy, and numerous efforts have been attempted to overcome MDR. To date, none of these attempts have yielded a tolerable and effective therapy to reverse MDR; thus, identification of new agents would be useful both clinically and scientifically.. To identify small molecule compounds that can reverse chemoresistance, we developed a 96-well plate high-throughput cell-based screening assay in a paclitaxel resistant ovarian cancer cell line. Coincubating cells with a sublethal concentration of paclitaxel in combination with each of 2,000 small molecule compounds from the National Cancer Institute Diversity Set Library, we identified a previously uncharacterized molecule, NSC23925, that inhibits Pgp1 and reverses MDR1 (Pgp1) but does not inhibit MRP or BCRP-mediated MDR. The cytotoxic activity of NSC23925 was further evaluated using a panel of cancer cell lines expressing Pgp1, MRP, and BCRP. We found that at a concentration of >10 microM NSC23925 moderately inhibits the proliferation of both sensitive and resistant cell lines with almost equal activity, but its inhibitory effect was not altered by co-incubation with the Pgp1 inhibitor, verapamil, suggesting that NSC23925 itself is not a substrate of Pgp1. Additionally, NSC23925 increases the intracellular accumulation of Pgp1 substrates: calcein AM, Rhodamine-123, paclitaxel, mitoxantrone, and doxorubicin. Interestingly, we further observed that, although NSC23925 directly inhibits the function of Pgp1 in a dose-dependent manner without altering the total expression level of Pgp1, NSC23925 actually stimulates ATPase activity of Pgp, a phenomenon seen in other Pgp inhibitors.. The ability of NSC23925 to restore sensitivity to the cytotoxic effects of chemotherapy or to prevent resistance could significantly benefit cancer patients.

Topics: Adenosine Triphosphatases; Antineoplastic Agents; ATP Binding Cassette Transporter, Subfamily B, Member 1; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Drug Screening Assays, Antitumor; Female; Fluoresceins; Humans; Models, Chemical; Ovarian Neoplasms; Paclitaxel; Piperidines; Quinolines

The isoquinoline peripheral benzodiazepine receptor ligand PK11195 increased drug (daunomycin)- and fluorochrome (calcein-AM) uptake and induced apoptosis detected by flow cytometry (FCM) technique, DNA electrophoretic analysis and poly(ADP-ribose) polymerase (PARP) cleavage in human multidrug-resistant myeloid leukemia (BL-60/VCR) and ovarian carcinoma (A2780/ADR) cells in vitro. The position of PK11195 with respect to drug-resistance modulator (DRM) efficiency, compared to the reference DRMs with the aid of FCM technique, was as follows: PSC833 > verapamil > PK11195 > vincristine. Our data show up to now not indicated observation that PK11195 possesses multidrug resistance modulating activity.

Topics: Antineoplastic Agents; Apoptosis; ATP Binding Cassette Transporter, Subfamily B, Member 1; Biological Transport; Carcinoma; Daunorubicin; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Drug Synergism; Female; Fluoresceins; Fluorescent Dyes; HL-60 Cells; Humans; Isoquinolines; Leukemia, Myeloid; Ligands; Mitochondrial Proteins; Ovarian Neoplasms; Receptors, GABA-A; Tumor Cells, Cultured