Including Vinca Alkaloids Research Articles

Focus on breast cancer.

We would like to acknowledge Fredi Rojo for his assistance in the preparation of the figures.

Dexamethasone and triamcinolone acetonide accumulation in mouse fibroblasts is differently modulated by the immunosuppressants cyclosporin A, FK506, rapamycin and their analogues, as well as by other P-glycoprotein ligands

In mouse fibroblasts (LMCAT cells) stably transfected with the reporter gene chloramphenicol acetyl transferase under the control of the mouse mammary tumor virus promoter (MMTV-CAT), cyclosporin A (CsA), FK506, and rapamycin (Rap) at micromolar concentrations potentiate dexamethasone- (Dex) induced CAT gene activity in a dose-dependent way (Renoir J.-M., Mercier-Bodard C., Hoffmann K., Le Bihan S., Ning Y. M., Sanchez E. R., Handschumacher R. E. and Baulieu E. E., Proc. Natl. Acad. Sci. U.S.A., 92, 1995, 4977–4981). In this work, we used LMCAT and 1471.1 cells, another mouse fibroblast cell line stably transfected with the MMTV-CAT construct, and found that exposure to immunosuppressants affected steroid-induced transcription differently. Indeed, all immunosuppressants, including inactive analogues, potentiated not only Dex- but also TA-induced CAT gene expression in LMCAT cells. The extent of this potentiation was 3 times lower for TA than for Dex. These immunosuppressants have no effect in 1471.1 cells. In addition, no difference of glucocorticosteroid affinity for the GR was observed in 1471.1 cells, in contrast to LMCAT cells. In both cell lines, the drugs tested increased [ 3H] Dex and [ 3H] TA (although to a lesser extent) accumulation. Since it is known that immunosuppressants can reverse the membrane Phospho-glycoprotein (P-gp) activity responsible for an active efflux of small hydrophobic molecules from numerous cell types, we therefore measured the relative efficiency of other P-gp ligands (including vinca alkaloids and the inactive CsA analogue, PSC833), on [ 3H] Dex and [ 3H] TA accumulation. In both cell lines, and depending on the drugs, reversal of Dex export was more pronounced than that of TA export (~11 times in LMCAT and ~2 times in 1471.1 cells). However, the antiprogestin/antiglucocorticosteroid RU 38 486 and its 17 β derivatives RU 49 953 which does not bind to GR, both identified as strong reversal molecules of P-gp activity, had respectively, no and a strong inhibiting effect on steroid accumulation in both cell lines. These results suggest that a mechanism resembling but different from P-gp can modulate steroid entry into these mouse fibroblasts. This is confirmed by the failure to demonstrate the presence of P-gp by immunoprecipitation and Western blot experiments in membrane preparations from both cell lines. From these data, we conclude: (i) that the two synthetic GR ligands do not accumulate similarly in mouse fibroblasts, (ii) that RU 49 953 increases steroid efflux, in contrast to other agents known to reverse P-gp activity (iii) that cellular entry and export of Dex and TA can be modulated by membrane efflux mechanism(s), different from P-gp, and (iiii) that immunosuppressant potentiation of Dex- and TA-induced CAT activity involves such a mechanism in LMCAT cells. In 1471.1 cells, the lack of any enhancing effect upon steroid-induced transcription of all the drugs tested, although they all increase steroid accumulation, suggests involvement of immunosuppressant-influenced factor(s) acting downstream from steroid entry, in the hormone receptor-mediated transcription pathway(s).

29] High-level expression of mouse Mdr3 P-glycoprotein in yeast Pichia pastoris and characterization of ATPase activity

This chapter characterizes the ATPase activity of mouse P-glycoproteins (Pgp) following selective detergent solubilization and reconstitution in Escherichia coli lipids of Pgp-rich membranes fractionated on sucrose gradients. Pgps, which are eukaryotic members of the adenosine triphosphate-binding cassette (ABC) superfamily of transporters, cause cellular resistance to a wide variety of structurally unrelated cytotoxic drugs, including Vinca alkaloids, anthracyclins, colchicine, and ionophore peptides, such as valinomycin and gramicidin D. The structural unit common to ABC transporters includes one membrane-associated region and one nucleotide-binding domain (NBD) of the Walker type. The system characterizes a large series of Mdr3 mutants showing alterations in TMDs and NBDs. The P . pastoris system is superior in several aspects to the available expression systems for production of Pgp and perhaps other ABC transporters.

Activation of NF-κB by Antineoplastic Agents: ROLE OF PROTEIN KINASE C

Paclitaxel can induce tumor necrosis factor (TNF) and interleukin-1 gene expression, similar to lipopolysaccharides. Since lipopolysaccharide-induced expression of TNF is related to activation of NF-kappaB, we determined whether NF-kappaB could be activated by paclitaxel. In the human lung adenocarcinoma cell line A549, paclitaxel activated NF-kappaB in a dose-dependent manner with maximal activation after 2-4 h. Since paclitaxel could up-regulate TNF and interleukin-1 secretion and subsequent NF-kappaB activation could be caused by these cytokines, the effect of two other groups of anticancer drugs including vinca alkaloids (vinblastine and vincristine) and anthracyclines (daunomycin and doxorubicin), neither of which induce TNF or interleukin-1 gene expression, were examined. Like paclitaxel, vinblastine, vincristine, daunomycin, and doxorubicin each caused activation of NF-kappaB. Therefore, it is unlikely that activation of NF-kappaB caused by these agents or by paclitaxel is mediated via cytokine up-regulation. Furthermore, actinomycin D and cycloheximide, inhibitors of transcription and translation, respectively, did not inhibit paclitaxel-induced NF-kappaB activation. Several other transcription factors such as AP-1, AP-2, CREB, SP-1, or TFIID were not activated by antineoplastic agents demonstrating specificity of NF-kappaB activation. The involvement of both subunits in the NF-kappaB DNA binding complex was demonstrated by its abrogation by anti-p65 and by supershift by anti-p50 antibodies. Since protein phosphorylation is implicated in the activation of NF-kappaB, the effect of anticancer drugs on protein kinase C activity was measured. Vincristine, daunomycin, and paclitaxel significantly increased protein kinase C activity, and vinblastine and doxorubicin caused similar trends. Following treatment with antineoplastics (1-4 h), cytoplasmic IkappaBalpha degradation occurred concomitantly with translocation of p65 to the nucleus. Specific protein kinase C inhibitors (bisindolylmaleimide (GF109203X) and calphostin C) blocked the activation of NF-kappaB by each compound. Hence, protein kinase C activation may contribute to NF-kappaB activation by antineoplastic agents.

Recombinant α-2b-interferon in classic Kaposi's sarcoma

Classic Kaposi's sarcoma (KS) is frequently observed in the Mediterranean area, and is an endemic disease in Sardinia, an island situated in the central Mediterranean. Retrospective and prospective studies conducted on the island at different times, starting from 1965 and concluding in 1988, have shown an extremely high incidence of this disorder of around 1.6/100 000 inhabitants per year. The therapeutic approach to KS is based on its clinical course and tends to be conservative when the disease is localized, but more aggressive when it is generalized. The localized forms are mainly treated by local therapy including surgery and/or diathermy, local infiltration with chemotherapeutic agents and radiology. In the generalized forms, the most frequent therapies include vinca alkaloids, bleomycin or combinations of drugs, or interferon. The present study presents the results obtained in 21 patients with classic KS treated with recombinant α-2b-inferferon.

Radiation resistance in a multidrug resistant human T-cell leukemia line

In clinical practice, cancers refractory to chemotherapy commonly appear to be comparatively radioresistant. One mechanism by which cancer cells become resistant to chemotherapy is pleiotropic multidrug resistance, characterized by cross resistance to a number of otherwise unrelated heterocyclic antineoplastic agents, including vinca alkaloids, anthracyclines, dactinomycin, and others. We have studied a drug sensitive human leukemia cell line, CEM; a pleiotropic multidrug resistant subline of CEM, CEM/VLB 100; VLB-1, a drug sensitive revertant subline arising during in vivo passage of CEM/VLB 100; and a methotrexate resistant subline of CEM, CEM-MTX. Using soft-agar colony formation after graded doses of X rays as an endpoint, we found that CEM, CEM-MTX, and CEM/VLB 100 had similar terminal slopes (D 0 = 0.66 Gy). However, the CEM/VLB 100 survival curve had a broader initial shoulder (n = 3.0, D q = 0.75 Gy) than did CEM (n = 1.6, D q = 0.25 Gy) or CEM/MTX (n = 1.0, D q = 0 Gy), suggesting that CEM/VLB 100 has an increased capacity to repair radiation-induced DNA damage. This was tested by comparing the cell lines' abilities to accumulate sublethal damage. In split dose recovery experiments, CEM/VLB 100 demonstrated increased ability to repair sublethal radiation damage following fractionated irradiation compared with the CEM parental line. Although it no longer demonstrated multidrug resistance, VLB-l still displayed diminished radiation sensitivity. On the basis of these and other investigators' results, we suggest that diminished radiation sensitivity is separate from, but can be closely associated with, the multidrug-resistant phenotype.