The Experts below are selected from a list of 279 Experts worldwide ranked by ideXlab platform
Bridget T Hill - One of the best experts on this subject based on the ideXlab platform.
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anti angiogenic vascular disrupting and anti metastatic activities of vinflunine the latest Vinca Alkaloid in clinical development
European Journal of Cancer, 2006Co-Authors: Anna Kruczynski, Bridget T Hill, Maura Poli, Romina Dossi, Eric Chazottes, Geraldine Berrichon, Christel Ricome, Raffaella Giavazzi, Giulia TarabolettiAbstract:Abstract The aim of this study was to investigate the anti-angiogenic, vascular-disrupting and anti-metastatic properties of vinflunine, the latest Vinca Alkaloid in phase III clinical development. The effects of vinflunine on in vitro endothelial cell functions relevant to the performance of an already formed vasculature and to the angiogenic process were evaluated. The in vivo anti-angiogenic properties of vinflunine were also investigated, as were its activity against a model of experimental metastasis. In vitro vinflunine induced a rapid change in the morphology of endothelial cells and disrupted the network of capillary-like structures, indicating potential vascular-disrupting activity. Furthermore, vinflunine showed anti-angiogenic properties, since it inhibited endothelial cell migration and the capacity of these cells to organise into a network of capillary-like structures. All these effects were observed under conditions that only marginally affect endothelial cell proliferation. In vivo , vinflunine inhibited bFGF-induced angiogenesis in Matrigel implants at doses 40–20-fold lower than its maximal therapeutic dose (MTD). Treatment of mice with vinflunine reduced the number of liver metastases induced by intrasplenic injection of LS174T cells, with significant effects also observed at low doses; i.e. 16-fold lower than the MTD. This study demonstrates that vinflunine expresses both vascular-disrupting and anti-angiogenic activities and induced marked effects against experimental metastases, all properties that support its ongoing clinical development.
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vinflunine the latest Vinca Alkaloid in clinical development a review of its preclinical anticancer properties
Critical Reviews in Oncology Hematology, 2001Co-Authors: Anna Kruczynski, Bridget T HillAbstract:Vinflunine is a new Vinca Alkaloid uniquely fluorinated, by the use of superacid chemistry, in a little exploited region of the catharanthine moiety. In vitro investigations have confirmed the mitotic-arresting and tubulin-interacting properties of vinflunine shared by other Vinca Alkaloids. However, differences in terms of the inhibitory effects of vinflunine on microtubules dynamics and its tubulin binding affinities have been identified which appear to distinguish it from the other Vinca Alkaloids. Vinflunine induced smaller spirals with a shorter relaxation time, effects, which might be associated with reduced neurotoxicity. Studies investigating the in vitro cytotoxicity of vinflunine in combination therapy have revealed a high level of synergy when vinflunine was combined with either cisplatin, mitomycin C, doxorubicin or 5-fluorouracil. Furthermore, although vinflunine appears to participate in P-glycoprotein-mediated drug resistance mechanisms, it has proved only a weak substrate for this protein and a far less potent inducer of resistance than vinorelbine. Vinflunine was identified in preclinical studies as having marked antitumour activity in vivo against a large panel of experimental tumour models, with tumour regressions being recorded in human renal and small cell lung cancer tumour xenografts. Overall its level of activity was superior to that of vinorelbine in many of the experimental models used. Interestingly, an in vivo study using a well vascularised adenocarcinoma of the colon has suggested that vinflunine mediates its antitumour activity at least in part via an antivascular mechanism, even at sub-cytotoxic doses. Therefore, these data provide a favourable preclinical profile for vinflunine, supporting its promising candidacy for clinical development. Phase I evaluations of vinflunine have been completed in Europe and phase II clinical trials are now ongoing.
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Vinca Alkaloid induced tubulin spiral formation correlates with cytotoxicity in the leukemic l1210 cell line
Biochemistry, 2000Co-Authors: Sharon Lobert, Chantal Etievant, Jacques Fahy, Bridget T Hill, Alain Duflos, John J. CorreiaAbstract:The ability of a class of C-20' modified Vinca Alkaloid congeners to induce tubulin spiral formation was investigated relative to their ability to inhibit microtubule assembly, their cytotoxicity against a leukemic cell line, L1210, and their measured and calculated partition coefficients. These studies were prompted by the observation that the energetics of Vinca Alkaloid-induced tubulin spiral polymers, or spiraling potential, is inversely related to their clinical dosage and are aimed at the long-term goal of developing the ability to predict the cytotoxic and antineoplastic properties of antimitotic drugs. We demonstrate here that Vinca-induced tubulin-spiraling potential is significantly correlated with cytotoxicity against L1210 cells. This is consistent with the size of spirals formed being proportional to the relaxation time for polymer redistribution, the lifetime of cell retention, and effects on microtubule ends and dynamics. Spiraling potential also correlates with calculated but not measured partition coefficients. Surprisingly, spiraling potential does not correlate with the ability to inhibit microtubule formation with purified tubulin or microtubule protein. For the set of C-20' modified compounds studied, the largest inhibitory effects on spiraling potential and cytotoxicity are caused by multiple sites of halogen (-F, -Cl) substitution with the introduction of increased rigidity in the ring. This suggests the C-20 ' position interacts with a hydrogen bond acceptor or an electrophilic region on the protein that electrostatically disfavors halogen substitutions. These studies are discussed in terms of the cellular mode of action of antimitotic drugs, particularly the importance of microtubule dynamics during mitosis and the factors that regulate those dynamics.
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antimitotic and tubulin interacting properties of vinflunine a novel fluorinated Vinca Alkaloid
Biochemical Pharmacology, 1998Co-Authors: Anna Kruczynski, Jean-marc Barret, Chantal Etievant, Francis Colpaert, Jacques Fahy, Bridget T HillAbstract:This study aimed to define the mechanism of action of vinflunine, a novel Vinca Alkaloid synthesised from vinorelbine using superacidic chemistry and characterised by superior in vivo activity to vinorelbine in preclinical tumour models. In vitro vinflunine cytotoxicity proved dependent on concentration and exposure duration, with ic50 values (72-hr exposures) generally ranging from 60–300 nM. Vinflunine induced G2 + M arrest, associated with mitotic accumulation and a concentration-dependent reduction of the microtubular network of interphase cells, accompanied by paracrystal formation. These effects, while comparable to those of vincristine, vinblastine or vinorelbine, were achieved with 3- to 17-fold higher vinflunine concentrations. However, vinflunine and the other Vincas all inhibited microtubule assembly at micromolar concentrations. Vinflunine, like vinblastine, vincristine and vinorelbine, appeared to interact at the Vinca binding domain, as judged by proteolytic cleavage patterns, and induced tubulin structural changes favouring an inhibition of GTP hydrolysis. However, vinflunine did not prevent [3H]vincristine binding to unassembled tubulin at concentrations ≤ 100 μM, and only weakly inhibited binding of [3H]vinblastine or [3H]vinorelbine. Indeed, specific binding of [3H]vinflunine to tubulin was undetectable by centrifugal gel filtration. Thus, the comparative capacities of these Vincas to bind to or to interfere with their binding to tubulin could be classified as: vincristine > vinblastine > vinorelbine > vinflunine. By monitoring alkylation of sulfhydryl groups, differential effects on tubulin conformation were identified with vinflunine and vinorelbine acting similarly, yet distinctively from vinblastine and vincristine. Overall, vinflunine appears to function as a definite inhibitor of tubulin assembly, while exhibiting quantitatively different tubulin binding properties to the classic Vinca Alkaloids.
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Vinflunine (20′,20′-difluoro- 3′,4′-dihydrovinorelbine), a novel Vinca Alkaloid, which participates in P-glycoprotein (Pgp)-mediated multidrug resistance in vivo and in vitro
Investigational New Drugs, 1998Co-Authors: Chantal Etievant, Anna Kruczynski, Jean-marc Barret, Dominique Perrin, Bridget T HillAbstract:Vinflunine (VFL) is a novel derivative of vinorelbine (NVB, Navelbine®), which has shown markedly superior antitumor activity to NVB, in various experimental animal models. To establish whether this new Vinca Alkaloid participates in P-glycoprotein (Pgp)-mediated multidrug resistance (MDR), VFL-resistant murine P388 cells (P388/VFL) were established in vivo and used in conjunction with the well established MDR P388/ADR subline, to define the in vivo resistance profile for VFL. P388/VFL cells proved cross-resistant to drugs implicated in MDR (other Vinca Alkaloids, doxorubicin, etoposide), but not to campothecin or cisplatin and showed an increased expression of Pgp, without any detectable alterations in topoisomerase II or in glutathione metabolism. The P388/ADR cells proved cross-resistant to VFL both in vivo and in vitro, and this VFL resistance was efficiently modulated by verapamil in vitro. Cellular transport experiments with tritiated-VFL revealed differential uptake by P388 sensitive and P388/ADR resistant cells, comparable with data obtained using tritiated-NVB. In various in vitro models of human MDR tumor cells, whilst full sensitivity was retained in cells expressing alternative non-Pgp-mediated MDR mechanisms, cross resistance was identified in Pgp-overexpressing cells. Differences were, however, noted in terms of the drug resistance profiles relative to the other Vincas, with tumor cell lines proving generally least cross-resistant to VFL. Overall, these results suggest that VFL, like other Vinca Alkaloids, participates in Pgp-mediated MDR, with tumor cells selected for resistance to VFL overexpressing Pgp, yet MDR tumor cell lines proved generally less cross resistant to VFL relative to the other Vinca Alkaloids.
Anna Kruczynski - One of the best experts on this subject based on the ideXlab platform.
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anti angiogenic vascular disrupting and anti metastatic activities of vinflunine the latest Vinca Alkaloid in clinical development
European Journal of Cancer, 2006Co-Authors: Anna Kruczynski, Bridget T Hill, Maura Poli, Romina Dossi, Eric Chazottes, Geraldine Berrichon, Christel Ricome, Raffaella Giavazzi, Giulia TarabolettiAbstract:Abstract The aim of this study was to investigate the anti-angiogenic, vascular-disrupting and anti-metastatic properties of vinflunine, the latest Vinca Alkaloid in phase III clinical development. The effects of vinflunine on in vitro endothelial cell functions relevant to the performance of an already formed vasculature and to the angiogenic process were evaluated. The in vivo anti-angiogenic properties of vinflunine were also investigated, as were its activity against a model of experimental metastasis. In vitro vinflunine induced a rapid change in the morphology of endothelial cells and disrupted the network of capillary-like structures, indicating potential vascular-disrupting activity. Furthermore, vinflunine showed anti-angiogenic properties, since it inhibited endothelial cell migration and the capacity of these cells to organise into a network of capillary-like structures. All these effects were observed under conditions that only marginally affect endothelial cell proliferation. In vivo , vinflunine inhibited bFGF-induced angiogenesis in Matrigel implants at doses 40–20-fold lower than its maximal therapeutic dose (MTD). Treatment of mice with vinflunine reduced the number of liver metastases induced by intrasplenic injection of LS174T cells, with significant effects also observed at low doses; i.e. 16-fold lower than the MTD. This study demonstrates that vinflunine expresses both vascular-disrupting and anti-angiogenic activities and induced marked effects against experimental metastases, all properties that support its ongoing clinical development.
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Characterization of cell death induced by vinflunine, the most recent Vinca Alkaloid in clinical development
British Journal of Cancer, 2002Co-Authors: Anna Kruczynski, Chantal Etievant, D Perrin, N Chansard, A Duflos, B T HillAbstract:Vinflunine, the most recent Vinca Alkaloid in clinical development, demonstrated superior antitumour activity to other Vincas in preclinical tumour models. This study aimed to define its molecular mechanisms of cell killing in both parental sensitive and vinflunine-resistant P388 leukaemia cells. Vinflunine treatment of these cells resulted in apoptosis characterized by DNA fragmentation and proteolytic cleavage of poly-(ADP-ribose) polymerase. Apoptosis-inducing concentrations of vinflunine caused c-Jun N-terminal kinase 1 stimulation, as well as caspases-3/7 activation. This activation of caspases and the induction of apoptosis could be inhibited by the caspase inhibitor acetyl-Asp-Glu-Val-Asp-aldehyde. Interestingly, the apoptosis signal triggered by vinflunine in these P388 cells was not mediated through Bcl-2 phosphorylation. In addition, when vinflunine resistance was developed in P388 cells, it was associated with resistance to vinflunine-induced apoptosis, as reflected by a loss of capacity to induce DNA fragmentation and PARP degradation, and characterized by increased levels of Bcl-2 and Bfl-1/A1. Therefore, these data indirectly implicate Bcl-2 and Bfl-1/A1 in vinflunine-induced cell death mechanisms.
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vinflunine the latest Vinca Alkaloid in clinical development a review of its preclinical anticancer properties
Critical Reviews in Oncology Hematology, 2001Co-Authors: Anna Kruczynski, Bridget T HillAbstract:Vinflunine is a new Vinca Alkaloid uniquely fluorinated, by the use of superacid chemistry, in a little exploited region of the catharanthine moiety. In vitro investigations have confirmed the mitotic-arresting and tubulin-interacting properties of vinflunine shared by other Vinca Alkaloids. However, differences in terms of the inhibitory effects of vinflunine on microtubules dynamics and its tubulin binding affinities have been identified which appear to distinguish it from the other Vinca Alkaloids. Vinflunine induced smaller spirals with a shorter relaxation time, effects, which might be associated with reduced neurotoxicity. Studies investigating the in vitro cytotoxicity of vinflunine in combination therapy have revealed a high level of synergy when vinflunine was combined with either cisplatin, mitomycin C, doxorubicin or 5-fluorouracil. Furthermore, although vinflunine appears to participate in P-glycoprotein-mediated drug resistance mechanisms, it has proved only a weak substrate for this protein and a far less potent inducer of resistance than vinorelbine. Vinflunine was identified in preclinical studies as having marked antitumour activity in vivo against a large panel of experimental tumour models, with tumour regressions being recorded in human renal and small cell lung cancer tumour xenografts. Overall its level of activity was superior to that of vinorelbine in many of the experimental models used. Interestingly, an in vivo study using a well vascularised adenocarcinoma of the colon has suggested that vinflunine mediates its antitumour activity at least in part via an antivascular mechanism, even at sub-cytotoxic doses. Therefore, these data provide a favourable preclinical profile for vinflunine, supporting its promising candidacy for clinical development. Phase I evaluations of vinflunine have been completed in Europe and phase II clinical trials are now ongoing.
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antimitotic and tubulin interacting properties of vinflunine a novel fluorinated Vinca Alkaloid
Biochemical Pharmacology, 1998Co-Authors: Anna Kruczynski, Jean-marc Barret, Chantal Etievant, Francis Colpaert, Jacques Fahy, Bridget T HillAbstract:This study aimed to define the mechanism of action of vinflunine, a novel Vinca Alkaloid synthesised from vinorelbine using superacidic chemistry and characterised by superior in vivo activity to vinorelbine in preclinical tumour models. In vitro vinflunine cytotoxicity proved dependent on concentration and exposure duration, with ic50 values (72-hr exposures) generally ranging from 60–300 nM. Vinflunine induced G2 + M arrest, associated with mitotic accumulation and a concentration-dependent reduction of the microtubular network of interphase cells, accompanied by paracrystal formation. These effects, while comparable to those of vincristine, vinblastine or vinorelbine, were achieved with 3- to 17-fold higher vinflunine concentrations. However, vinflunine and the other Vincas all inhibited microtubule assembly at micromolar concentrations. Vinflunine, like vinblastine, vincristine and vinorelbine, appeared to interact at the Vinca binding domain, as judged by proteolytic cleavage patterns, and induced tubulin structural changes favouring an inhibition of GTP hydrolysis. However, vinflunine did not prevent [3H]vincristine binding to unassembled tubulin at concentrations ≤ 100 μM, and only weakly inhibited binding of [3H]vinblastine or [3H]vinorelbine. Indeed, specific binding of [3H]vinflunine to tubulin was undetectable by centrifugal gel filtration. Thus, the comparative capacities of these Vincas to bind to or to interfere with their binding to tubulin could be classified as: vincristine > vinblastine > vinorelbine > vinflunine. By monitoring alkylation of sulfhydryl groups, differential effects on tubulin conformation were identified with vinflunine and vinorelbine acting similarly, yet distinctively from vinblastine and vincristine. Overall, vinflunine appears to function as a definite inhibitor of tubulin assembly, while exhibiting quantitatively different tubulin binding properties to the classic Vinca Alkaloids.
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Vinflunine (20′,20′-difluoro- 3′,4′-dihydrovinorelbine), a novel Vinca Alkaloid, which participates in P-glycoprotein (Pgp)-mediated multidrug resistance in vivo and in vitro
Investigational New Drugs, 1998Co-Authors: Chantal Etievant, Anna Kruczynski, Jean-marc Barret, Dominique Perrin, Bridget T HillAbstract:Vinflunine (VFL) is a novel derivative of vinorelbine (NVB, Navelbine®), which has shown markedly superior antitumor activity to NVB, in various experimental animal models. To establish whether this new Vinca Alkaloid participates in P-glycoprotein (Pgp)-mediated multidrug resistance (MDR), VFL-resistant murine P388 cells (P388/VFL) were established in vivo and used in conjunction with the well established MDR P388/ADR subline, to define the in vivo resistance profile for VFL. P388/VFL cells proved cross-resistant to drugs implicated in MDR (other Vinca Alkaloids, doxorubicin, etoposide), but not to campothecin or cisplatin and showed an increased expression of Pgp, without any detectable alterations in topoisomerase II or in glutathione metabolism. The P388/ADR cells proved cross-resistant to VFL both in vivo and in vitro, and this VFL resistance was efficiently modulated by verapamil in vitro. Cellular transport experiments with tritiated-VFL revealed differential uptake by P388 sensitive and P388/ADR resistant cells, comparable with data obtained using tritiated-NVB. In various in vitro models of human MDR tumor cells, whilst full sensitivity was retained in cells expressing alternative non-Pgp-mediated MDR mechanisms, cross resistance was identified in Pgp-overexpressing cells. Differences were, however, noted in terms of the drug resistance profiles relative to the other Vincas, with tumor cell lines proving generally least cross-resistant to VFL. Overall, these results suggest that VFL, like other Vinca Alkaloids, participates in Pgp-mediated MDR, with tumor cells selected for resistance to VFL overexpressing Pgp, yet MDR tumor cell lines proved generally less cross resistant to VFL relative to the other Vinca Alkaloids.
Chantal Etievant - One of the best experts on this subject based on the ideXlab platform.
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Characterization of cell death induced by vinflunine, the most recent Vinca Alkaloid in clinical development
British Journal of Cancer, 2002Co-Authors: Anna Kruczynski, Chantal Etievant, D Perrin, N Chansard, A Duflos, B T HillAbstract:Vinflunine, the most recent Vinca Alkaloid in clinical development, demonstrated superior antitumour activity to other Vincas in preclinical tumour models. This study aimed to define its molecular mechanisms of cell killing in both parental sensitive and vinflunine-resistant P388 leukaemia cells. Vinflunine treatment of these cells resulted in apoptosis characterized by DNA fragmentation and proteolytic cleavage of poly-(ADP-ribose) polymerase. Apoptosis-inducing concentrations of vinflunine caused c-Jun N-terminal kinase 1 stimulation, as well as caspases-3/7 activation. This activation of caspases and the induction of apoptosis could be inhibited by the caspase inhibitor acetyl-Asp-Glu-Val-Asp-aldehyde. Interestingly, the apoptosis signal triggered by vinflunine in these P388 cells was not mediated through Bcl-2 phosphorylation. In addition, when vinflunine resistance was developed in P388 cells, it was associated with resistance to vinflunine-induced apoptosis, as reflected by a loss of capacity to induce DNA fragmentation and PARP degradation, and characterized by increased levels of Bcl-2 and Bfl-1/A1. Therefore, these data indirectly implicate Bcl-2 and Bfl-1/A1 in vinflunine-induced cell death mechanisms.
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Vinca Alkaloid induced tubulin spiral formation correlates with cytotoxicity in the leukemic l1210 cell line
Biochemistry, 2000Co-Authors: Sharon Lobert, Chantal Etievant, Jacques Fahy, Bridget T Hill, Alain Duflos, John J. CorreiaAbstract:The ability of a class of C-20' modified Vinca Alkaloid congeners to induce tubulin spiral formation was investigated relative to their ability to inhibit microtubule assembly, their cytotoxicity against a leukemic cell line, L1210, and their measured and calculated partition coefficients. These studies were prompted by the observation that the energetics of Vinca Alkaloid-induced tubulin spiral polymers, or spiraling potential, is inversely related to their clinical dosage and are aimed at the long-term goal of developing the ability to predict the cytotoxic and antineoplastic properties of antimitotic drugs. We demonstrate here that Vinca-induced tubulin-spiraling potential is significantly correlated with cytotoxicity against L1210 cells. This is consistent with the size of spirals formed being proportional to the relaxation time for polymer redistribution, the lifetime of cell retention, and effects on microtubule ends and dynamics. Spiraling potential also correlates with calculated but not measured partition coefficients. Surprisingly, spiraling potential does not correlate with the ability to inhibit microtubule formation with purified tubulin or microtubule protein. For the set of C-20' modified compounds studied, the largest inhibitory effects on spiraling potential and cytotoxicity are caused by multiple sites of halogen (-F, -Cl) substitution with the introduction of increased rigidity in the ring. This suggests the C-20 ' position interacts with a hydrogen bond acceptor or an electrophilic region on the protein that electrostatically disfavors halogen substitutions. These studies are discussed in terms of the cellular mode of action of antimitotic drugs, particularly the importance of microtubule dynamics during mitosis and the factors that regulate those dynamics.
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antimitotic and tubulin interacting properties of vinflunine a novel fluorinated Vinca Alkaloid
Biochemical Pharmacology, 1998Co-Authors: Anna Kruczynski, Jean-marc Barret, Chantal Etievant, Francis Colpaert, Jacques Fahy, Bridget T HillAbstract:This study aimed to define the mechanism of action of vinflunine, a novel Vinca Alkaloid synthesised from vinorelbine using superacidic chemistry and characterised by superior in vivo activity to vinorelbine in preclinical tumour models. In vitro vinflunine cytotoxicity proved dependent on concentration and exposure duration, with ic50 values (72-hr exposures) generally ranging from 60–300 nM. Vinflunine induced G2 + M arrest, associated with mitotic accumulation and a concentration-dependent reduction of the microtubular network of interphase cells, accompanied by paracrystal formation. These effects, while comparable to those of vincristine, vinblastine or vinorelbine, were achieved with 3- to 17-fold higher vinflunine concentrations. However, vinflunine and the other Vincas all inhibited microtubule assembly at micromolar concentrations. Vinflunine, like vinblastine, vincristine and vinorelbine, appeared to interact at the Vinca binding domain, as judged by proteolytic cleavage patterns, and induced tubulin structural changes favouring an inhibition of GTP hydrolysis. However, vinflunine did not prevent [3H]vincristine binding to unassembled tubulin at concentrations ≤ 100 μM, and only weakly inhibited binding of [3H]vinblastine or [3H]vinorelbine. Indeed, specific binding of [3H]vinflunine to tubulin was undetectable by centrifugal gel filtration. Thus, the comparative capacities of these Vincas to bind to or to interfere with their binding to tubulin could be classified as: vincristine > vinblastine > vinorelbine > vinflunine. By monitoring alkylation of sulfhydryl groups, differential effects on tubulin conformation were identified with vinflunine and vinorelbine acting similarly, yet distinctively from vinblastine and vincristine. Overall, vinflunine appears to function as a definite inhibitor of tubulin assembly, while exhibiting quantitatively different tubulin binding properties to the classic Vinca Alkaloids.
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Vinflunine (20′,20′-difluoro- 3′,4′-dihydrovinorelbine), a novel Vinca Alkaloid, which participates in P-glycoprotein (Pgp)-mediated multidrug resistance in vivo and in vitro
Investigational New Drugs, 1998Co-Authors: Chantal Etievant, Anna Kruczynski, Jean-marc Barret, Dominique Perrin, Bridget T HillAbstract:Vinflunine (VFL) is a novel derivative of vinorelbine (NVB, Navelbine®), which has shown markedly superior antitumor activity to NVB, in various experimental animal models. To establish whether this new Vinca Alkaloid participates in P-glycoprotein (Pgp)-mediated multidrug resistance (MDR), VFL-resistant murine P388 cells (P388/VFL) were established in vivo and used in conjunction with the well established MDR P388/ADR subline, to define the in vivo resistance profile for VFL. P388/VFL cells proved cross-resistant to drugs implicated in MDR (other Vinca Alkaloids, doxorubicin, etoposide), but not to campothecin or cisplatin and showed an increased expression of Pgp, without any detectable alterations in topoisomerase II or in glutathione metabolism. The P388/ADR cells proved cross-resistant to VFL both in vivo and in vitro, and this VFL resistance was efficiently modulated by verapamil in vitro. Cellular transport experiments with tritiated-VFL revealed differential uptake by P388 sensitive and P388/ADR resistant cells, comparable with data obtained using tritiated-NVB. In various in vitro models of human MDR tumor cells, whilst full sensitivity was retained in cells expressing alternative non-Pgp-mediated MDR mechanisms, cross resistance was identified in Pgp-overexpressing cells. Differences were, however, noted in terms of the drug resistance profiles relative to the other Vincas, with tumor cell lines proving generally least cross-resistant to VFL. Overall, these results suggest that VFL, like other Vinca Alkaloids, participates in Pgp-mediated MDR, with tumor cells selected for resistance to VFL overexpressing Pgp, yet MDR tumor cell lines proved generally less cross resistant to VFL relative to the other Vinca Alkaloids.
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vinflunine 20 20 difluoro 3 4 dihydrovinorelbine a novel Vinca Alkaloid which participates in p glycoprotein pgp mediated multidrug resistance in vivo and in vitro
Investigational New Drugs, 1998Co-Authors: Chantal Etievant, Anna Kruczynski, Jean-marc Barret, Dominique Perrin, Bridget T HillAbstract:Vinflunine (VFL) is a novel derivative of vinorelbine (NVB, Navelbine®), which has shown markedly superior antitumor activity to NVB, in various experimental animal models. To establish whether this new Vinca Alkaloid participates in P-glycoprotein (Pgp)-mediated multidrug resistance (MDR), VFL-resistant murine P388 cells (P388/VFL) were established in vivo and used in conjunction with the well established MDR P388/ADR subline, to define the in vivo resistance profile for VFL. P388/VFL cells proved cross-resistant to drugs implicated in MDR (other Vinca Alkaloids, doxorubicin, etoposide), but not to campothecin or cisplatin and showed an increased expression of Pgp, without any detectable alterations in topoisomerase II or in glutathione metabolism. The P388/ADR cells proved cross-resistant to VFL both in vivo and in vitro, and this VFL resistance was efficiently modulated by verapamil in vitro. Cellular transport experiments with tritiated-VFL revealed differential uptake by P388 sensitive and P388/ADR resistant cells, comparable with data obtained using tritiated-NVB. In various in vitro models of human MDR tumor cells, whilst full sensitivity was retained in cells expressing alternative non-Pgp-mediated MDR mechanisms, cross resistance was identified in Pgp-overexpressing cells. Differences were, however, noted in terms of the drug resistance profiles relative to the other Vincas, with tumor cell lines proving generally least cross-resistant to VFL. Overall, these results suggest that VFL, like other Vinca Alkaloids, participates in Pgp-mediated MDR, with tumor cells selected for resistance to VFL overexpressing Pgp, yet MDR tumor cell lines proved generally less cross resistant to VFL relative to the other Vinca Alkaloids.
John J. Correia - One of the best experts on this subject based on the ideXlab platform.
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Methods for studying Vinca Alkaloid interactions with tubulin.
Methods in molecular medicine, 2007Co-Authors: Sharon Lobert, John J. CorreiaAbstract:Vinca Alkaloids play a vital role in chemotherapy protocols for a wide range of hematological and solid tumors. Studies of drug interactions with the drug target, tubulin or microtubules, have helped us to understand the cytotoxic and toxic effects. We present here in vivo and in vitro methods for studying Vinca Alkaloid interactions with tubulin. In vivo methods for examining drug effects on cell proliferation and intracellular tubulin or microtubules and direct visualization of drug effects by fluorescence microscopy are presented. In vitro methods for measuring drug affinity for tubulin by analytical ultracentrifugation, kinetics of drug binding by light scattering and drug effects on microtubules by turbidity are also presented.
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Vinca Alkaloid induced tubulin spiral formation correlates with cytotoxicity in the leukemic l1210 cell line
Biochemistry, 2000Co-Authors: Sharon Lobert, Chantal Etievant, Jacques Fahy, Bridget T Hill, Alain Duflos, John J. CorreiaAbstract:The ability of a class of C-20' modified Vinca Alkaloid congeners to induce tubulin spiral formation was investigated relative to their ability to inhibit microtubule assembly, their cytotoxicity against a leukemic cell line, L1210, and their measured and calculated partition coefficients. These studies were prompted by the observation that the energetics of Vinca Alkaloid-induced tubulin spiral polymers, or spiraling potential, is inversely related to their clinical dosage and are aimed at the long-term goal of developing the ability to predict the cytotoxic and antineoplastic properties of antimitotic drugs. We demonstrate here that Vinca-induced tubulin-spiraling potential is significantly correlated with cytotoxicity against L1210 cells. This is consistent with the size of spirals formed being proportional to the relaxation time for polymer redistribution, the lifetime of cell retention, and effects on microtubule ends and dynamics. Spiraling potential also correlates with calculated but not measured partition coefficients. Surprisingly, spiraling potential does not correlate with the ability to inhibit microtubule formation with purified tubulin or microtubule protein. For the set of C-20' modified compounds studied, the largest inhibitory effects on spiraling potential and cytotoxicity are caused by multiple sites of halogen (-F, -Cl) substitution with the introduction of increased rigidity in the ring. This suggests the C-20 ' position interacts with a hydrogen bond acceptor or an electrophilic region on the protein that electrostatically disfavors halogen substitutions. These studies are discussed in terms of the cellular mode of action of antimitotic drugs, particularly the importance of microtubule dynamics during mitosis and the factors that regulate those dynamics.
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Energetics of Vinca Alkaloid interactions with tubulin.
Methods in enzymology, 2000Co-Authors: Sharon Lobert, John J. CorreiaAbstract:Publisher Summary This chapter presents a detailed discussion of the energetics of interactions between Vinca rosea L. (Vinca) Alkaloids, antimitotic chemotherapeutic agents, and tubulin, the major protein constituent of microtubules and the mitotic spindle. Vinca Alkaloids induce tubulin to form indefinite spirals and ordered paracrystals that compete with microtubule formation. Drug binding is known to be thermodynamically linked to spiral formation. In vivo , Vinca Alkaloids cause mitotic arrest at substoichiometric concentrations by acting at the ends of microtubules to diminish dynamic instability in mitotic spindles. It obtains a full thermodynamic description of the energetics of Vinca Alkaloid-induced tubulin self-association over a range of temperature and buffer conditions for a group of Vinca Alkaloid congeners. The chapter describes the use of sedimentation velocity, the quantitative fitting of weight average sedimentation coefficient data, and its applicability to extracting the energetics of Vinca Alkaloid-tubulin interactions. Sedimentation velocity has proven to be the best method for determining Vinca Alkaloid binding affinities and drug-induced tubulin spiralling potential. It compares results obtained with four clinically useful Vinca Alkaloid congeners. There is a quantitative description of the impact of allosteric effectors such as guanine nucleotides, pH, salt, and divalent cations on the system. The chapter relates these energetic findings to the structure of tubulin, the structure and dynamics of microtubules, and the implications for antimitotic and antineoplastic effectiveness with specific emphasis on tubulin isotype effects.
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Energetics of Vinca Alkaloid interactions with tubulin isotypes: Implications for drug efficacy and toxicity
Cell motility and the cytoskeleton, 1998Co-Authors: Sharon Lobert, Anthony Frankfurter, John J. CorreiaAbstract:A number of Vinca Alkaloids, including vincristine, vinblastine, and vinorelbine, are currently used in cancer chemotherapy. These three Vinca Alkaloids interact differently with a range of solid and hematologic tumors. To test the possibility that the tubulin isotype composition is an important determinant in antineoplastic efficacy, we determined thermodynamic parameters for Vinca Alkaloid interactions with purified b-tubulin isotypes, abII or abIII, as well as mixtures of abII and abIII, abII and abI&IV, or abIII and abI&IV (referred to as isotype-depleted tubulin) by quantitative sedimentation velocity. Vincristine-, vinblastine-, or vinorelbine-induced isotype self-association was studied at 25°C in 10 mM Pipes, pH 6.9, 1 mM MgSO4, and 2 mM EGTA in the presence of 50 µM GTP or GDP. For all three drugs, we observed no significant differences in overall affinities, K1K2 ,o r in GDP enhancement of purified isotypes compared to unfractionated tubulin, suggesting that differential antitumor efficacy observed clinically for these Vinca Alkaloids is not determined by tissue isotype composition. Small, but significant differences in the individual binding parameters, K 1 and K2, are found in the vincristine data. In the presence of vincristine and GTP, K 1, the affinity of drug for tubulin heterodimers, tends to be larger for purified abII- or abIII-tubulin compared to unfractionated tubulin. Furthermore, the apparent dimerization constant, K 2 , at physiologically significant drug concentrations is larger for these purified isotypes. WhenabII- and abIII-tubulin are combined, the cooperativity between drug binding and spiral formation approaches that of unfractionated PC-tubulin. These differences are not observed in the presence of vinblastine or vinorelbine. The differences found with vincristine may be implicated in the dose-limiting neurotoxicity found with this drug, but not found with vinblastine or vinorelbine. Cell. Motil. Cytoskeleton 39:107‐121, 1998. r 1998 Wiley-Liss, Inc.
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divalent cation and ionic strength effects on Vinca Alkaloid induced tubulin self association
Biophysical Journal, 1997Co-Authors: Sharon Lobert, C A Boyd, John J. CorreiaAbstract:We present here a systematic study of ionic strength and divalent cation effects on Vinca Alkaloid-induced tubulin spiral formation. We used sedimentation velocity experiments and quantitative fitting of weight-average sedimentation coefficients versus free drug concentrations to obtain thermodynamic parameters under various solution conditions. The addition of 50–150 mM NaCl to our standard buffer (10 mM piperazine-N,N'-bis(2-ethanesulfonic acid), 1 mM Mg, 50 microM GDP or GTP, pH 6.9) enhances overall vinblastine- or vincristine-induced tubulin self-association. As demonstrated in previous studies, GDP enhances overall self-association more than GTP, although in the presence of salt, GDP enhancement is reduced. For example, in 150 mM NaCl, GDP enhancement is 0.24 kcal/mol for vinblastine and 0.36 kcal/mol for vincristine versus an average enhancement of 0.87 (+/- 0.34) kcal/mol for the same drugs in the absence of salt. Wyman linkage analysis of experiments with vinblastine or vincristine over a range of NaCl concentrations showed a twofold increase in the change in NaCl bound to drug-induced spirals in the presence of GTP compared to GDP. These data indicate that GDP enhancement of Vinca Alkaloid-induced tubulin self-association is due in part to electrostatic inhibition in the GTP state. In the absence of NaCl, we found that vinblastine and 1 mM Mn2+ or Ca2+ causes immediate condensation of tubulin. The predominant aggregates observed by electron microscopy are large sheets. This effect was not found with 1 mM Mg2+. At 100 microM cation concentrations (Mn2+, Mg2+, or Ca2+), GDP enhances vinblastine-induced spiral formation by 0.55 (+/- 0.26) kcal/mol. This effect is found only in K2, the association of liganded heterodimers at the ends of growing spirals. There is no GDP enhancement of K1, the binding of drug to heterodimer, although K1 is dependent upon the divalent cation concentration. NaCl diminishes tubulin condensation, probably by inhibiting lateral association, and allows an investigation of higher divalent cation concentrations. In the presence of 150 mM NaCl plus 1 mM divalent cations (Mn2+, Mg2+, or Ca2+) GDP enhances vinblastine-induced spiral formation by 0.35 (+/- 0.21) kcal/mol. Relaxation times determined by stopped-flow light scattering experiments in the presence of 150 mM NaCl and vincristine are severalfold longer than those in the presence of vinblastine, consistent with a mechanism involving the redistribution of longer polymers. Unlike previous results in the absence of NaCl, relaxation times in the presence of NaCl are only weekly protein concentration dependent, suggesting the absence of annealing or an additional rate-limiting step in the mechanism.
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regulation of Vinca Alkaloid induced apoptosis by nf kappab ikappab pathway in human tumor cells
Molecular Cancer Therapeutics, 2004Co-Authors: Yi Huang, Yong Fang, Jennifer M Dziadyk, Xueming Zhu, Meihua Sui, Weimin FanAbstract:Antimicrotubule Vinca Alkaloids, such as vinblastine and vincristine, interfere with the dynamics of microtubules and have shown significant cell killing activity in a variety of tumor cells through induction of apoptosis. The mechanism by which Vinca Alkaloids induce apoptosis is not entirely clear. In this study, we found that glucocorticoids inhibit Vinca Alkaloid-induced apoptosis without affecting G(2)-M arrest in human breast cancer BCap37 cells and human epidermoid tumor KB cells, suggesting that Vinca Alkaloid-induced apoptosis may occur via a pathway independent of cell cycle arrest. Further analyses indicated that Vinca Alkaloids cause significant degradation of IkappaBalpha, which in turn results in nuclear factor-kappaB (NF-kappaB) activation. Transfection of antisense IkappaBalpha in BCap37 cells sensitizes Vinca Alkaloid-induced apoptosis. Moreover, in vitro kinase assays show that the activity of IkappaB kinase (IKK) was activated by Vinca Alkaloids and was not affected by glucocorticoids. Stable transfection of dominant-negative deletional mutant IkappaBalpha, which is insensitive to IKK-mediated phosphorylation and degradation, resulted in the inhibition of Vinca Alkaloid-induced NF-kappaB activation and reduced sensitivity of tumor cells to Vinca Alkaloid-induced apoptosis. These findings suggest that the NF-kappaB/IkappaB signaling pathway may contribute to the mediation of Vinca Alkaloid-induced apoptosis in human tumor cells.
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Regulation of Vinca Alkaloid-induced apoptosis by NF-kappaB/IkappaB pathway in human tumor cells.
Molecular cancer therapeutics, 2004Co-Authors: Yi Huang, Yong Fang, Jennifer M Dziadyk, Xueming Zhu, Meihua Sui, Weimin FanAbstract:Antimicrotubule Vinca Alkaloids, such as vinblastine and vincristine, interfere with the dynamics of microtubules and have shown significant cell killing activity in a variety of tumor cells through induction of apoptosis. The mechanism by which Vinca Alkaloids induce apoptosis is not entirely clear. In this study, we found that glucocorticoids inhibit Vinca Alkaloid-induced apoptosis without affecting G(2)-M arrest in human breast cancer BCap37 cells and human epidermoid tumor KB cells, suggesting that Vinca Alkaloid-induced apoptosis may occur via a pathway independent of cell cycle arrest. Further analyses indicated that Vinca Alkaloids cause significant degradation of IkappaBalpha, which in turn results in nuclear factor-kappaB (NF-kappaB) activation. Transfection of antisense IkappaBalpha in BCap37 cells sensitizes Vinca Alkaloid-induced apoptosis. Moreover, in vitro kinase assays show that the activity of IkappaB kinase (IKK) was activated by Vinca Alkaloids and was not affected by glucocorticoids. Stable transfection of dominant-negative deletional mutant IkappaBalpha, which is insensitive to IKK-mediated phosphorylation and degradation, resulted in the inhibition of Vinca Alkaloid-induced NF-kappaB activation and reduced sensitivity of tumor cells to Vinca Alkaloid-induced apoptosis. These findings suggest that the NF-kappaB/IkappaB signaling pathway may contribute to the mediation of Vinca Alkaloid-induced apoptosis in human tumor cells.