Changes in doxorubicin distribution and toxicity in mice pretreated with the cyclosporin analogue SDZ PSC 833

SDZ PSC 833 (PSC 833) is a cyclosporin A analogue that is under clinical investigation in combination with doxorubicin (Dx) or other anticancer agents as a type-1 multidrug resistance (MDR-1)-reversing agent. The present study was focused on the effects of PSC 833 on the distribution and toxicity of Dx in non-tumor-bearing CDF1 male mice. Mice were given PSC 833 i.p. at 30 min before i.v. Dx treatment. Dx levels were determined by a high-performance liquid chromatography (HPLC) assay at different times during a 72-h period following Dx treatment in the serum, heart, intestine, liver, kidney, and adrenals of mice. In all tissues, Dx area under the concentrationtime curve (AUC) values were much greater in mice receiving 10 mg/kg Dx in combination with 12.5 or 25 mg/kg PSC 833 than in mice receiving Dx alone. The highest increase in Dx concentrations was found in the intestine, liver, kidney, and adrenals. Lower, albeit significant, differences were found in the heart. PSC 833 did not appear to influence either urinary or fecal Dx elimination or Dx metabolism to a great extent. Doses of PSC 833 devoid of any toxicity potentiated the acute and delayed toxicity of Dx dramatically. The mechanism responsible for this enhanced toxicity has not yet been elucidated but is likely to be related to an increased tissue retention of Dx due to inhibition of the P-glycoprotein (Pgp) pump by PSC 833, as has recently been proposed for cyclosporin A.Abbreviations MDR Multidrug resistance - mdr-1 gene multidrug resistance-1 gene - Pgp P-glycoprotein - PSC 833 SDZ PSC 833 - Dx doxorubicin - HPLC high-performance liquid chromatography - AUC area under the concentration-time curve     

Dose-dependent brain penetration of SDZ PSC 833, a novel multidrug resistance-reversing cyclosporin,in rats

 This study quantitatively assessed the brain penetration of a potent P-glycoprotein inhibitor, SDZ PSC 833, and its effect on the blood-brain barrier (BBB) permeability (PS) of an anticancer agent, vincristine. At lower doses of SDZ PSC 833 the brain penetration, defined as the brain-to-blood partition coefficient (Kp), was very low in spite of the high lipophilicity of this compound. At higher doses, however, the brain penetration of SDZ PSC 833 was markedly increased. Since the blood pharmacokinetics of SDZ PSC 833 proved to be linear in the dose range studied, these results demonstrated a dose-dependent brain passage of SDZ PSC 833. The brain passage of cyclosporin A was also found to be dose-dependent. However, the potency of SDZ PSC 833 in inhibiting the efflux mechanism at the BBB was higher than that of cyclosporin A since 10 times higher doses of cyclosporin A were required to obtain the same Kp values recorded for SDZ PSC 833. Moreover, the coadministration of SDZ PSC 833 increased the brain penetration of cyclosporin A, whereas the latter did not modify that of SDZ PSC 833. The increase in SDZ PSC 833 and vincristine PS values observed at high blood levels of SDZ PSC 833 are consistent with the hypothesis of a saturation of the P-glycoprotein pump present at the BBB. The involvement of P-glycoprotein in the brain passage of SDZ PSC 833 could be of great significance for clinical application of the drug in the treatment of brain cancers when it is given in combination with anticancer agents. Received: 8 October 1995/Accepted: 25 January 1996     

PSC833逆转人骨肉瘤细胞系多药耐药性的研究

目的 探讨PSC833对骨肉瘤耐药细胞系U2OS/DOX和SaOS/DOX的逆转作用及其机制。方法 用MTT法和细胞计数法测定PSC833逆转MDR的活性;用流式细胞仪观察PSC833对细胞内Rh123积聚和外排的影响;用免疫荧光技术定量检测逆转剂对P-gp表达水平的影响。结果 PSC833对DOX敏感系U2OS和SaOS无明显作用。PSC833能显著增加DOX对U2OS/DOX和SaOS/DOX的细胞毒性作用,逆转效果明显强于VPL和CSA,且存在剂量依赖关系。PSC833能减少耐药细胞系内Rh123的外排,增加Rh123的积聚,而对P-gp的表达水平没有明显影响。结论 PSC833能逆转U2OS/DOX和SaOS/DOX的MDR,其效果明显优于VPL和CSA,逆转机理在于抑制耐药系细胞膜上P-gp的功能,而对P-gp的表达水平没有影响。     

Intracellular Levels of Two Cyclosporin Derivatives Valspodar (PSC 833) and Cyclosporin A Closely Associated with Multidrug Resistance-modulating Activity in Sublines of Human Colorectal Adenocarcinoma HCT-15

P-Glycoprotein, which mediates multidrug resistance (MDR) in cancer chemotherapy, is a principal target of Cyclosporin A and [3'-keto-Bmt¹]-[Val²]-cyclosporin (valspodar; PSC 833). To clarify mechanisms contributing to the different MDR-modulating activities of valspodar and Cyclosporin A, we investigated the relation of the intracellular levels of the two Cyclosporin derivatives to their modulating effect on MDR in different P-glycoprotein-expressing human colorectal carcinoma HCT-15 cells (parental HCT-15 and adriamycin-resistant sublines). In this study, valspodar was found to be much more potent than Cyclosporin A in both sensitizing resistant cells to MDR-related anticancer drugs (e.g., adriamycin, vincristine and paclitaxel (taxol)) and increasing 2-[6-amino-3-imino-3H-xanthen-9-yl]benzoic acid methyl ester (rhodamine 123) retention and [G-³H]vincristine sulfate ([³H]vincristine) accumulation in these cells. Furthermore, a good correlation was detected between P-glycoprotein levels and the MDR-reversing effect of valspodar. In contrast, the effects of Cyclosporin A could not be linked to P-glycoprotein levels in the MDR cells. In addition, the intracellular accumulation of valspodar was found to be 3–6 fold higher than that of Cyclosporin A in four sublines and verapamil, an inhibitor of P-glycoprotein-mediated transport, enhanced the accumulation of Cyclosporin A, but not valspodar. These results suggested that valspodar accumulation is not actively regulated by the P-glycoprotein-mediated efflux system     

Phase I Study of Intravenous PSC-833 and Doxorubicin: Reversal of Multidrug Resistance

PSC-833 reverses multidrug resistance by P-glycoprotein at concentrations <1000 ng/ml. A phase I study of PSC-833 and doxorubicin was conducted to determine the maximum tolerated dose and to investigate pharmacokinetics. PSC-833 was intravenously infused as a 2-h loading dose (LD) and a subsequent 24-h continuous dose (CD). Doxorubicin was infused over 5 min, 1 h after the LD. The starting dose was 1 mg/kg for both LD and CD with 30 mg/m² doxorubicin; these dosages were increased to 2 and 10 mg/kg and 50 mg/m², respectively. Thirty-one patients were treated. Nausea/ vomiting was controllable with granisetron and dexamethasone. Neutropenia and ataxia were dose limiting. Steady-state concentrations of PSC-833 >1000 ng/ml were achieved at a 2 mg/kg LD and a 10 mg/kg CD. Ex-vivo bioassay revealed that activity in serum for reversing multidrug resistance was achieved in all patients; IC₅₀ of P-glycoprotein expressing 8226/Dox₆; in patients' serum was decreased from 5.9 to 1.3 μg/ml ( P <0.0001) by PSC-833 administration. Doxorubicin clearance was 24.3±13.7 (mean±SD) liter/h/m², which was lower than the 49.0±16.9 liter/h/m² without PSC-833 ( P <0.0001). The relationship between doxorubicin exposure and neutropenia did not differ between patients treated and not treated with PSC-833. The recommended phase II dose of PSC-833 was 2 and 10 mg/kg for LD and CD, respectively, which achieved a sufficient concentration in serum to reverse drug resistance, as confirmed by bioassay. The dose of doxorubicin should be reduced to 40 mg/m², not because of the pharmacodynamic interaction between PSC-833 and doxorubicin affecting hematopoiesis, but because of pharmacokinetic interaction.     

环胞菌素A 逆转数种人类胶质瘤细胞多药耐药性的体外实验研究

 目的　探讨环胞菌素A体外逆转人类胶质瘤细多药耐药性的作用及其机理。方法　采用有MDR1和MRP表达的人类胶质瘤细系 ,通过放射自显影观察应用环胞菌素A前后抗癌药物在细胞内的积累与外排量。结果　在有MDR1和MRP表达的人类胶质瘤细胞系中 ,加入环胞菌素A后细胞内抗癌药物积累量显著增加 (P <0 .0 5 )。结论　环胞菌素A可增加耐药细胞对抗癌药的敏感性 ,在体外能有效地逆转入类胶质瘤细胞的多药耐药性。其作用机制除了与细胞膜上的P -糖蛋白竞争性结合、抑制药物外排 ,对MRP过度表达的胶质瘤细胞系也有逆转作用 ,这可能与细胞类型有关。     

Modulation of Multidrug Resistance by SDZ PSC 833 in Leukemic and Solid-tumor-bearing Mouse Models

P-Glycoprotein inhibitors, including the nonimmunosuppressive cyclosporin D analog SDZ PSC 833 (PSC 833), have been developed to circumvent multidrug resistance. In the present study, the potential of PSC 833 in reversing multidrug resistance was evaluated in various systemic treatment models with leukemic and solid-tumor-bearing mice. Having a relatively wide therapeutic window of daily p.o. doses from 12.5 to 75 mg/kg, PSC 833 significantly improved the antileukemic activity of the anticancer drugs adriamycin (ADM), vincristine (VCR) and etoposide (VP-16) given i.p. or i.v. against i.p.-inoculated vincristine-resistant P388 tumor (P388/VCR). PSC 833 in combination with i.p.-injected anticancer drugs in optimal schedule and dosage induced apparent cures in some leukemic mice, whereas no cures were obtained with the cyclosporin A/anticancer drug combinations. PSC 833 combined with i.v.-injected anticancer drugs was highly active, but not curative, against P388/VCR and parental P388 tumors (maximum T/C>175%). PSC 833 in combination with intravenous treatment with ADM showed prominent anti-solid-tumor activity against s.c.-inoculated colon adenocarcinoma 26 and human colorectal adenocarcinoma HCT-15. Against colon adenocarcinoma 26, the PSC 833/ADM combinations induced cure in two or three of six mice. PSC 833/ADM combinations significantly inhibited the growth of the tumor with maximum percent inhibitions of 83 and 73% in the early and advanced stages of the HCT-15 tumor models, respectively. The present study demonstrated that PSC 833 is highly active in potentiating the antitumor activity of systemically administered ADM, VCR and VP-16 against four murine and human tumors with a relatively wide therapeutic window of daily p.o. dose range of 12.5–100 mg/kg.     

Cyclosporin A Enhances Susceptibility of Multi-drug Resistant Human Cancer Cells to Anti-P-glycoprotein Antibody-dependent Cytotoxicity of Monocytes, but Not of Lymphocytes

Cyclosporin A (CsA) was previously found to bind to P-glycoprotein expressed on multidrug-resistant (MDR) cancer cells. In the present study, the effect of CsA on anti-P-glycoprotein monoclonal antibody (mAb)-dependent cell-mediated cytotoxicity (ADCC) against human MDR cells was examined. The ADCC reaction was assessed by 4-h ⁵¹Cr-release assay. Highly purified lymphocytes (> 99%) and monocytes (>99%) obtained from blood mononuclear cells (MNC) of healthy donors were used as effector cells. CsA decreased the cytotoxic activity of MNC against MDR cells, but enhanced their ADCC activity in the presence of anti-P-glycoprotein mAb MRK16. Lymphocyte-mediated ADCC and natural killer activity against MDR cells were also suppressed by addition of CsA. CsA induced a significant dose-dependent increase in monocyte-mediated ADCC activity. Interestingly, pretreatment of MDR cancer cells, but not of monocytes, with CsA significantly enhanced ADCC activity mediated by monocytes, but not by lymphocytes. A CsA analog (PSC833) and FK-506, but not verapamil also increased the sensitivity of MDR cells to ADCC by monocytes. CsA did not affect the binding of monocytes to MDR cells in the presence of MRK16 mAb. These results indicate that CsA may directly enhance the susceptibility of MDR cancer cells to the monocyte-mediated ADCC reaction.     

非霍奇金淋巴瘤多药耐药逆转的临床研究

目的 :探讨环胞霉素 A(Cs A)联合他莫昔芬 (TAM)逆转非霍奇金淋巴瘤 (NHL )多药耐药的临床疗效。方法 :采用免疫组织化学标记链亲和素生物素法检测 NHL的 P-糖蛋白表达。将 P-糖蛋白表达阳性者分层随机分为两组 ,比较 Cs A联合 TAM加化疗组与单用化疗组的疗效。结果 :P-糖蛋白的阳性表达率在初治 NHL 为 9.6 % ,在复发难治 NHL 为 79.2 % (P<0 .0 0 1)。Cs A联合 TAM对逆转 NHL 的多药耐药有一定作用 ,加逆转剂组的化疗疗效高于不加逆转剂组 (P<0 .0 5 )。结论 :Cs A联合 TAM逆转 NHL 的多药耐药是安全和具有一定疗效的。     

Synergistic Effect of Cyclosporin A and Verapamil in Overcoming Vincristine Resistance of Multidrug-resistant Cultured Human Leukemia Cells

Reversal of vincristine (VCR) resistance by cyclosporin A (CyA) or the combination of CyA and verapamil (VER) was investigated by using four P-glycoprotein (P-gp)-associated human multidrug-resistant (MDR) cell lines (K562/ADM, KYO-1, HEL and CMK). Drug sensitivity was expressed as 50% inhibitory concentration (IC₅₀). The degree of reversal of resistance was expressed as x -fold decrease by dividing the IC₅₀ value without modifier(s) by that with modifier(s). CyA overcame P-gp-associated MDR significantly in all four MDR cell lines. Reversal of VCR resistance by CyA appeared to be dose-dependent. In the case of low-grade MDR cell lines (KYO-1, HEL and CMK), CyA at the low concentration of 0.5 μg/ml was still effective. The degree of reversal of VCR resistance in this condition was greater (6.3- to 16-fold decrease) in the low-grade MDR cell lines than in a high-grade MDR cell line (K562/ADM) (2.9-fold decrease). At a high concentration (5 μg/ml) of CyA, however, it was greater (240-fold decrease) in the high-grade MDR cell lines than in the low-grade MDR cell line (20- to 100-fold decrease). This indicates that concentration of CyA required for overcoming drug resistance in MDR cells was dependent on the degree of drug resistance. CyA overcame VCR resistance more efficiently than VER. The combination of CyA and VER enhanced reversal of VCR resistance in a supra-additive or at least an additive manner and overcame VCR resistance at low concentrations of both modifiers that are clinically achievable with safety.     

Comparative Study on Reversal Efficacy of SDZ PSC 833, Cyclosporin a and Verapamil on Multidrug Resistance in vitro and in vivo

A non-immunosuppressive cyclosporin, SDZ PSC 833 (PSC833), shows a reversal effect on multidrug resistance (MDR) by functional modulation of MDR1 gene product, P-glycoprotein. The objective of the present study was to compare the reversal efficacy of three multidrug resistance modulators, PSC833, cyclosporin A (CsA) and verapamil (Vp). PSC833 has approximately 3-10-fold greater potency than CsA and Vp with respect to the restoring effect on reduced accumulation of doxorubicin (ADM) and vincristine (VCR) in ADM-resistant K562 myelogenous leukemia cells (K562/ADM) in vitro and also on the sensitivity of K562/ADM to ADM and VCR in in vitro growth inhibition. The in vivo efficacy of a combination of modifiers (PSC833 and CsA: 50 mg/kg, Vp 100 mg/kg administered p.o. 4 h before the administration of anticancer drugs) with anticancer drugs (ADM 2.5 mg/kg i.p., Q4D days 1, 5 and 9, VCR 0.05 mg/kg i.p., QD days 1-5) was tested in ADM-resistant P388-bearing mice. PSC833 significantly enhanced the increase in life span by more than 80%, whereas CsA and Vp enhanced by less than 50%. This reversal potency, which exceeded that of CsA and Vp, was confirmed by therapeutic experiments using colon adenocarcinoma 26-bearing mice. These results demonstrated that PSC833 has signficant potency to reverse MDR in vitro and in vivo, suggesting that PSC833 is a good candidate for reversing multidrug resistance in clinical situations.     

Effect of P-glycoprotein modulation with cyclosporin A on cerebrospinal fluid penetration of doxorubicin in non-human primates

Purpose: P-glycoprotein (Pgp) is a transmembrane drug efflux pump that is expressed in multidrug-resistant cancer cells and in a variety of normal tissues, including brain capillary endothelial cells which comprise the blood-brain barrier. We studied the effects of the Pgp inhibitor, cyclosporin A (CsA), on the cerebrospinal fluid (CSF) penetration of the Pgp substrate, doxorubicin, in non-human primates. Methods: The animals received doxorubicin alone (2.0 mg/kg i.v. over 60 min) or doxorubicin (1 mg/kg i.v. over 60 min) and CsA (loading dose 4.0 mg/kg i.v. over 2 h, followed by continuous infusion of 12 mg/kg per day over 48 h). Plasma and CSF were collected over 48 h and the doxorubicin concentration was measured by reverse-phase high-pressure liquid chromatography (HPLC) with fluorescence detection (detection limit 5 nM). A two-compartment model was fitted to the plasma concentration-time data. Results: Pgp was demonstrated to be present in the epithelium of the choroid plexus by immunohistochemical methods, indicating that CSF drug penetration could be used as a surrogate for blood-brain barrier penetration. Steady state whole blood CsA concentrations, which were measured with a fluorescence-polarization immunoassay (TDX) that detects both CsA and its metabolites, ranged from 551–1315 μg/l at 24 h. The clearance of doxorubicin in four animals was reduced by 34%, 38%, 45% and 49% when given with CsA. The doxorubicin concentration in the CSF was <5 nM in all animals, both after doxorubicin alone and doxorubicin with CsA. Conclusions: The Pgp inhibitor, CsA, at a concentration that alters systemic clearance of doxorubicin, does not appear to significantly increase the CSF penetration of doxorubicin. Received: 18 May 1999 / Accepted: 3 September 1999     

Augmentation by Bispecific F(ab')2 Reactive with P-Glycoprotein and CD3 of Cytotoxicity of Human Effector Cells on P-Glycoprotein Positive Human Renal Cancer Cells

A bispecific F(ba')₂ was constructed that was composed of two Fab fragments, one derived from anti-CD3 monoclonal antibody (mAb) (OKT3) and the other from anti P-glycoprotein mAb (MRK 16). This bispecific F(ab')₂ enhanced the binding and cytotoxicity of human peripheral blood mononuclear cells (PBMCs) on P-glycoprotein-positive human kidney cancer cells (ADMHK/E). It had no effect on the cytotoxicity of PBMCs on P-glycoprotein-negative HK/E cells [long-term cultured HK/E (LCHK/E)]. Control F(ab')₂ composed of OKT3 or MRK16 alone did not influence the cytotoxicity of PBMCs on ADMHK/E cells. These findings suggest that the MRK16-OKT3 bispecific F(ab')₂ may be therapeutically beneficial in treatment of human multidrug-resistant cancers.     

Differential effects of the immunosuppressive agents cyclosporin A, tacrolimus and sirolimus on drug transport by multidrug resistance proteins

Purpose We sought to determine the effects of the immunosuppressants, cyclosporin A (CsA), tacrolimus and sirolimus, on drug transport by the ATP-binding cassette proteins, P-glycoprotein (Pgp; ABCB1), multidrug resistance protein-1 (MRP-1; ABCC1) and breast cancer resistance protein (BCRP; ABCG2), and the major vault protein lung resistance protein (LRP). Methods Cellular content of mitoxantrone, a Pgp, MRP-1 and BCRP substrate, was measured by flow cytometry in cells overexpressing these proteins following incubation with and without CsA, tacrolimus or sirolimus. Interaction of BCRP with these compounds was studied by photolabeling and ATPase assays. Nuclear–cytoplasmic distribution of doxorubicin was studied by confocal microscopy in cells overexpressing LRP. Results CsA increased cellular drug uptake in cells overexpressing Pgp, MRP-1 or BCRP and nuclear drug uptake in cells overexpressing LRP at the clinically achievable concentration of 2.5 μM. Tacrolimus enhanced cellular drug uptake at 1 μM, but not at 0.08 μM, its clinically achievable concentration, and did not enhance nuclear drug uptake. Sirolimus enhanced cellular drug uptake in cells overexpressing Pgp, MRP-1 and BCRP with optimal effects at 2.5 μM, but was effective at its clinically achievable concentration of 0.25 μM if cells were pre-incubated for at least 30 min before drug exposure, and also enhanced nuclear drug uptake at 0.25 μM. BCRP modulation by all three immunosuppressive agents was associated with competitive binding to the drug transport sites. Conclusions CsA, tacrolimus and sirolimus modulate drug transport by Pgp, MRP-1 and BCRP and CsA and sirolimus modulate drug transport by LRP at concentrations that differ from immunosuppressive concentrations and maximum tolerated concentrations.     

Reversing Effect of Agosterol A, a Spongean Sterol Acetate, on Multidrug Resistance in Human Carcinoma Cells

The effect of agosterol A, a novel polyhydroxylated sterol acetate isolated from a marine sponge, on P-glycoprotein (P-gp)-mediated multidrug-resistant cells (KB-C2) and the multidrug resistance associated protein (MRPl)-mediated multidrug-resistant cells (KB-CV60) was examined. Agosterol A reversed the resistance to colchicine in KB-C2 cells and also the resistance to vincristine in KB-CV60 cells at 3 to 10 μM concentration. Agosterol A at 3 μM increased the vincristine concentration in both KB-C2 cells and KB-CV60 cells to the level in parental KB-3-1 cells. Agosterol A also decreased the efflux of vincristine from both KB-C2 cells and KB-CV60 cells to the level seen in KB-3-1 cells. Agosterol A inhibited the [³H]azidopine-photolabeling of P-gp and also inhibited the uptake of [³H]S-(2,4-dinitrophenyl)glutathione (DNP-SG) in inside-out membrane vesicles prepared from KB-CV60 cells. We conclude that agosterol A directly inhibited drug efflux through P-gp and/or MRP1.     

Circumvention of multidrug resistance by a quinoline derivative, MS-209, in multidrug-resistant human small-cell lung cancer cells and its synergistic interaction with cyclosporin A or verapamil

Purpose and methods: To develop a clinically useful approach to circumvent P-glycoprotein (P-gp)-mediated multidrug resistance (MDR) in MDR human small-cell lung cancer (SCLC), we examined the ability of a novel quinoline compound, MS-209, to reverse MDR by inhibition of P-gp function in combination with other MDR-reversing drugs using a cytotoxicity assay. Results: We established MDR human SCLC cells by culture in medium with gradually increasing concentrations of adriamycin (ADM). Compared with the parental human SCLC cells, SBC-3, the MDR variant SBC-3 cells obtained (SBC-3/ADM) were highly resistant to various chemotherapeutic agents due to P-gp expression. MS-209 reversed the resistance to ADM and vincristine (VCR) of SBC-3/ADM and H69/VP cells in a dose-dependent manner. Moreover, MS-209 in combination with cyclosporin A (CsA) or verapamil (VER) synergistically enhanced the antitumor effects of ADM and VCR on SBC-3/ADM cells. MS-209 restored ADM incorporation and this effect was enhanced by CsA and VER, suggesting that these synergistic effects were due to competitive inhibition of P-gp function. Conclusion: MS-209 in combination with CsA or VER might increase the efficacy of these chemotherapeutic agents against MDR human SCLC cells. Received: 10 December 1997 / Accepted: 16 April 1998     

Tetrandrine achieved plasma concentrations capable of reversing MDR in vitro and had no apparent effect on doxorubicin pharmacokinetics in mice

Purpose Tetrandrine (Tet), a multidrug resistant (MDR) modulator, was a potential candidate for use in cancer therapy and exhibited potent biological activity in vitro and in vivo when combined with anticancer agents such as doxorubicin, paclitaxel. Our aims were to determine whether serum concentration of Tet, which was capable of blocking P-gp in vitro, could be safely achieved in mice and whether Tet induced pharmacokinetic alterations in serum doxorubicin disposition in mice. Methods Tet of 30 mg/kg dose used to reverse MDR was administrated intraperitoneally in mice. Plasma Tet and serum doxorubicin concentration were analyzed by HPLC. CYP 3A4 activity was examined by HPLC with the substrate of nifedipine. Results More than 1 μmol/L of Tet could at least tenfold reverse MDR in vitro. The plasma peak concentration of Tet was about 2 μmol/L and not less than 1 μmol/L until 18 h following Tet administration (i.p.) at 30 mg/kg. These suggested that the concentrations of Tet that were sufficient to inhibit P-gp might be achieved in mice receiving 30 mg/kg of Tet. Importantly, no significant difference was demonstrated between the doxorubicin pharmacokinetic parameters obtained in mice received doxorubicin only and doxorubicin plus Tet. This implied that Tet of 30 mg/kg did not alter the profiles of pharmacokinetics of doxorubicin including the clearance and AUC of doxorubicin. Furthermore, Tet did not significantly affect on CYP 3A4 activity in human liver microsomes until more than 25 μmol/L. Conclusions Tet at the tested dose of combination treatment could achieve plasma concentrations that reversed MDR in experimental models and it had no apparent effect on doxorubicin pharmacokinetics in mice and CYP 3A4 activity in human liver microsomes. Chun-Ling Dai and Hui-Yu Xiong equally contributed to this work. Grant support: China National Natural Sciences Foundation No. 30672407 and Key project Foundation of Guangdong Province No. 2005B10401042 and 985 Key Subject Project Foundation of State Key Laboratory of Oncology in Southern China.     

米非司酮对人耐药卵巢癌细胞增殖、凋亡及其对紫杉醇敏感性的影响

背景与目的:米非司酮是有效的孕酮受体拮抗剂。研究发现,米非司酮对体内外卵巢癌细胞均具有生长抑制作用,但机制尚不清楚。本研究旨在探讨米非司酮对人耐药卵巢癌细胞A2780/T增殖、凋亡及其对紫杉醇敏感性的影响,为临床应用米非司酮治疗耐药性卵巢癌提供实验依据。方法:体外培养人卵巢癌耐药细胞A2780/T,采用CCK-8法检测单用米非司酮及合用紫杉醇时对A2780/T细胞增殖的影响,分析米非司酮与紫杉醇在抑制耐药卵巢癌细胞增殖中的相互作用。采用流式细胞术分析米非司酮及米非司酮联合紫杉醇对A2780/T细胞凋亡的影响。结果:实验所选各种浓度(0.625～20μg/mL)米非司酮对A2780/T和A2780细胞均有一定程度的生长抑制作用,并呈浓度依赖性。当紫杉醇浓度为1.25或2.5μg/mL,合用米非司酮浓度为20、10、5、2.5、1.25或0.625μg/mL时,能显著抑制A2780/T细胞的增殖,并显示两种药物的协同作用(q>1.15)。当紫杉醇浓度为0.625或5μg/mL时,仅表现为两种药物的相加作用(0.85相似文献   

Antitumor Activity of a Novel Quinoline Derivative, TAS-103, with Inhibitory Effects on Topoisomerases I and II

A novel quinoline derivative, TAS-103 (6-[[2-(dimethyIamino)ethyl]amino]-3-hydroxy-7 H -indeno[2,l-c]quinolin-7-one dihydrochloride), was developed as an anticancer agent targeting topoisomerases (topo) I and II, with marked efficacy in solid tumors. TAS-103 inhibited topo I and II (IC₅₀: 2 μM, 6.5 μM ) at a concentration similar to or lower than those of previous agents, and had a strong cytotoxic effect on P388 and KB cells (IC₅₀,: 0.0011 μM, 0.0096 μM ). TAS-103 stabilized topo I and II-DNA cleavable complexes in KB cells, generating a similar amount of topo II-DNA complex to that induced by etoposide (VP-16) but a smaller amount of topo I-DNA complex than that produced by camptothecin (CPT). In the in vivo study, intermittent i.v. administration was markedly effective against s.c.-implanted murine tumors. Furthermore, TAS-103 had marked efficacy against various lung metastatic tumors, and a broad antitumor spectrum in human tumor xenografts (derived from lung, colon, stomach, breast, and pancreatic cancer). The efficacy of TAS-103 was generally greater than that of irinotecan (CPT-11), VP-16, or cis -diamminedichloroplatinum (CDDP).     

重组腺病毒介导入野生型p53,GM-CSF和B7-1基因对肿瘤化疗耐药细胞生物学行为的影响

目的：探讨重组腺病毒分导入野生型ｐ５３,ＧＭ－ＣＳＦ和Ｂ７－１基因对肿瘤化疗耐药细胞生物学行为的影响,为临床使用该重组腺病毒治疗多药耐药的肿瘤提供实验基础。方法：选用ｐ５３异常的ＫＢ－ｓ（ＶＣＲ敏感）和ＫＢ－ｖ２００（ＶＣＲ耐药）细胞作为肿瘤化疗药物敏感和耐药的模式细胞,感染携带人野生型ｐ５３,ＧＭ－ＣＳＦ和Ｂ７－１基因的重组腺病毒后,观察这两种转基因癌细胞的生物学行为（包括药物敏感性）的变化。结果：药物敏感和耐药细胞都对腺病毒易感,重组腺病毒携带的三个外源基因（ｐ５３、ＧＭ－ＣＳＦ、Ｂ７－１基因）在两种细胞中都能得到有效表达,并且能抑制它们的生长及诱导其凋亡。耐药细胞 ＫＢ－ｖ２００在转染该重组腺病毒 ４８ｈ后,其细胞膜上 Ｐｇｐ糖蛋白的泵出药物的功能却受到显著影响,表现为罗丹明１２３在其细胞内的积累增加。ＭＴＦ的实验结果也显示出其对ＶＣＲ药物敏感性的增加,裸鼠体内实验证实了感染上述重组腺病毒的ＫＢ－ｖ２００细胞的致瘤性降低,同时能增加对化疗药物ＶＣＲ的敏感性。结论：实验研究结果提示,使用该重组腺病毒并结合化疗药物,对临床治疗多药耐药的肿瘤可能会更有效。