The chemosensitizer cyclosporin A enhances the toxic side-effects of doxorubicin in the rat

the feasibility of using chemosensitizers in the circumvention of P-glycoprotein-mediated multidrug resistance has been shown in many studies. We recently reported on the chemosensitizing effect of cyclosporin A (CsA) on doxorubicin in a rat solid tumour model. Using the same experimental design we investigated the side-effects of the combination treatment. During the 35-day experiment doxorubicin treatment caused dose-dependent weight loss, which was enhanced by combination treatment with CsA. The main doxorubicin-related side-effects were myelosuppression (transient leucopenia and thrombopenia) and nephrotoxicity. Damage to the kidney was severe, leading to a nephrotic syndrome and resulting in ascites, pleural effusion, hypercholesterolaemia and hypertriglyceridaemia. These toxicities were enhanced by the addition of the chemosensitizer CsA. Mild doxorubicin-related cardiomyopathy and minimal hepatotoxicity were seen on histological examination. There were no signs of enhanced toxicity of the combination treatment in tissues with known high expression levels of P-glycoprotein, like the liver, adrenal gland and large intestine. CsA had a low toxicity profile, as it only caused a transient rise in bilirubin. In conclusion, the chemosensitizer CsA enhanced the side-effects of the anticancer drug doxorubiein without altering the toxicity pattern. There was no evidence of a therapeutic gain by adding CsA to doxorubicin, compared to single-agent treatment with doxorubicin in 25%–33% higher doses, because of the enhanced toxicity of the combination treatment.Abbreviations CsA cyclosporin A - DOX doxorubicin - MDR multidrug resistance - PBS phosphate-buffered saline This work was supported by the Dr Daniël den Hoed Foundation, Rotterdam, The Netherlands     

甲基莲心碱对长春新碱抑制人胃癌细胞增殖作用的影响

目的：观察甲基莲心碱（Nef）在体外对长春新碱抑制人胃癌细胞增殖及诱导人胃癌细胞凋亡的影响。方法：采用MTT比色法、软琼脂克隆形成法检测药物的细胞毒性作用,并用流式细胞术、AO/EB荧光双染色法测定Nef对长春新碱诱导人胃癌细胞凋亡的影响。结果：2.5、5、10μmol/LNef能增强长春新碱对人胃癌细胞（SGC7901）增殖的抑制作用;10μmol/LNef能增强长春新碱（0.1、0.5、2、4μg/ml）诱导SGC7901细胞凋亡。结论：甲基莲心碱能增强长春新碱抑制人胃癌细胞增殖及诱导人胃癌细胞凋亡,为一种低毒高效的化疗增敏剂。     

紫杉醇联合5-Aza-dC对非小细胞肺癌细胞NCI-H446生长抑制作用的研究

目的探讨紫杉醇（PAC）联合DNA甲基化酶抑制剂5-氮杂-2＇-脱氧胞苷（5-Aza-d C）对非小细胞肺癌细胞NCI-H446增殖迁徙及侵袭能力的影响。方法将人小细胞肺癌细胞NCI-H446给予紫杉醇及5-Aza-d C干预处理,根据药物干预方式的不同分为对照组、紫杉醇组及联合用药组;应用CCK-8法检测各组NCI-H446细胞增殖能力的差异;划痕实验和Transwell实验检测各组NCI-H446细胞迁移和侵袭能力的差异。结果 CCK-8结果显示PAC及5-Aza-d C均可抑制NCI-H446细胞的增殖活性,且呈时间依赖性。48 h后紫杉醇组及联合用药组NCI-H446细胞的增殖能力较对照组明显减弱（P〈0.01）;划痕实验结果显示划痕形成24 h后,对照组划痕愈合率为（69.15±0.837）%。而在紫杉醇组划痕处愈合率为（47.30±0.783）%;联合用药组划痕愈合率为（43.45±0.862）%。紫杉醇组及联合用药组NCI-H446细胞在迁移能力方面较对照组差异有统计学意义（P〈0.01）;Transwell实验结果显示对照组NCI-H446细胞转染穿过基质胶的细胞数量为（151.4±6.88）个,紫杉醇组为（66.8±5.17）个,联合用药组为（40.2±4.55）个。紫杉醇组及联合用药组NCI-H446细胞的侵袭能力较对照组差异有统计学意义（P〈0.01）。结论 5-Aza-d C作为化疗增敏剂可增加非小细胞肺癌细胞NCI-H446对紫杉醇的敏感性,从而提高紫杉醇对非小细胞肺癌的化疗效果。     

Selective cyclooxygenase inhibitors increase paclitaxel sensitivity in taxane-resistant ovarian cancer by suppressing P-glycoprotein expression

Objective

The purpose of this study was to investigate whether selective cyclooxygenase (COX) inhibitors promote paclitaxel-induced apoptosis in taxane-resistant ovarian cancer cells by suppressing MDR1/P-glycoprotein (P-gp) expression.

Methods

Taxane-resistant ovarian cancer cells were cultured with paclitaxel alone or combined with a selective COX inhibitors. The expression patterns of MDR1/P-gp and the ability of COX inhibitors to inhibit growth of taxane-resistant ovarian cancer cells were measured. The efficacy of prostaglandin E₂ (PGE₂) supplementation was measured to evaluate the mechanisms involved in suppressing MDR1 gene expression.

Results

P-gp was upregulated in taxane-resistant ovarian cancer cells compared to paired paclitaxel-sensitive ovarian cancer cells. An 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay showed that selective COX inhibitors significantly enhanced the cytotoxic effects of paclitaxel in taxane-resistant ovarian cancer cells via a prostaglandin-independent mechanism. These increased apoptotic effects were further verified by measuring an increased percentage of cells in sub-G1 stage using flow cytometry. Selective COX inhibitors suppressed MDR1 and P-gp expression. Moreover, combined treatment with paclitaxel and selective COX inhibitors increased poly (ADP-ribose) polymerase (PARP) cleavage in taxane-resistant ovarian cancer cells.

Conclusion

Selective COX inhibitors significantly promote paclitaxel-induced cell death in taxane-resistant ovarian cancer cells in a prostaglandin-independent manner. COX inhibitors could be potent therapeutic tools to promote paclitaxel sensitization of taxane-resistant ovarian cancers by suppressing MDR1/P-gp, which is responsible for the efflux of chemotherapeutic agents.     

Reversal of multidrug resistance by novel cyclosporin A analogues and the cyclopeptolide SDZ 214-103 biosynthesized in vitro

It was shown that cyclopeptolide SDZ 214-103 (10 M) is more active in rhodamine-123 accumulation in actinomycin-d-resistant human lymphoma cells CCRF/ACTD400 than cyclosporin A (10 M), but equipotent in the doxorubicin-resistant Friend erythroleukemia cell line F4-6/ADR. In F4-6/ADR cells, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cytotoxicity assay showed comparable cytotoxic effects of doxorubicin at various concentrations in the presence of SDZ 214-103 and cyclosporin A. For the other novel cyclosporin A analogues minor multidrug-resistance-modulating potency was demonstrated. At equipotent modulating doses of verapamil (10 M) and cyclosporin A (10 M) in the MTT assay regarding doxorubicin cytotoxicity, cyclosporin A was efficient in the rhodamine-123-uptake assay while verapamil was not active when identical incubation times were used.Abbreviations MDR multidrug resistance - Pgp-170 P-glycoprotein with a molecular mass of 170 kDa - D-Hiv D-2-hydroxyisovaleric acid     

一氧化氮供体型化合物化疗增敏效应

一氧化氮（NO）化疗增敏机制主要包括调节低氧诱导因子-1α表达水平、经典 NO 信号通路、与其他分子的反应产物结合3种途径。传统 NO 供体型化合物硝普盐、有机硝酸酯、S-亚硝基硫醇、偶氮二醇烯鎓盐、非甾体抗炎药等的抗瘤及化疗增敏效应引起了广泛的关注。     

Modulation of multidrug resistance by BIBW22BS in blasts of de novo or relapsed or persistent acute myeloid leukemia ex vivo

The phenylpteridine derivative BIBW22BS (BIBW22) is a potent modulator of multidrug resistance (MDR). We investigated BIBW22 in comparison to dexniguldipine and verapamil as modifier of MDR in blasts of de novo, relapsed or persistent acute myeloid leukemia (AML) in vitro. All patients with relapsed or persistent AML had been pretreated with idarubicin and cytosine arabinoside. The degree of MDR was determined by efflux kinetics of rhodamine 123 (R123), daunorubicin, and idarubicin measured by flow cytometry (FACS). A total of 51 patients with AML, 25 de novo and 26 relapsed or persistent, were investigated. While only 6 out of 25 de novo AML blast populations showed moderate efflux of R123 and daunorubicin, 17 out of 26 blast populations of relapsed or persistent AML had an efflux between 20% and 44% within 15 min ex vivo. This efflux could be significantly inhibited by 1 M BIBW22, 1 M dexniguldipine, or 10 M verapamil. For idarubicin we found an effusion of 40±9% within 15 min in all blast populations that could not be inhibited by the modulators. Clinically achievable drug concentrations causing only moderate side-effects are in the range of 0.5 M dexniguldipine and 3 M verapamil. Up to now, BIBW22 has not been investigated clinically. Thus, the potential toxicity of concentrations of 0.5–1 M BIBW22, sufficient for an optimal efflux inhibition ex vivo, is not known yet. We conclude from our ex vivo investigations in blast populations of de novo, relapsed or persistent AML that BIBW22 is a potent modulator of MDR.Abbreviations AML acute myeloid leukemia - MDR multidrug resistance     

The novel anthraquinone derivative IMP1338 induces death of human cancer cells by p53-independent S and G2/M cell cycle arrest

To identify novel small molecules that induce selective cancer cell death, we screened a chemical library containing 1040 compounds in HT29 colon cancer and CCD18-Co normal colon cells, using a phenotypic cell-based viability assay system with the Cell Counting Kit-8 (CCK-8). We discovered a novel anthraquinone derivative, N-(4-[{(9,10-dioxo-9,10-dihydro-1-anthracenyl)sulfonyl}amino]phenyl)-N-methylacetamide (IMP1338), which was cytotoxic against the human colon cancer cells tested. The MTT cell viability assay showed that treatment with IMP1338 selectively inhibited HCT116, HCT116 p53^−/−, HT29, and A549 cancer cell proliferation compared to that of Beas2B normal epithelial cells. To elucidate the cellular mechanism underlying the cytotoxicity of IMP1338, we examined the effect of IMP1338 on the cell cycle distribution and death of cancer cells. IMP1338 treatment significantly arrested the cell cycle at S and G2/M phases by DNA damage and led to apoptotic cell death, which was determined using FACS analysis with Annexin V/PI double staining. Furthermore, IMP1338 increased caspase-3 cleavage in wild-type p53, p53 knockout HCT116, and HT29 cells as determined using immunoblotting. In addition, IMP1338 markedly induced the phosphorylation of histone H2AX and Chk1 in both cell lines while the combination of 5-fluorouracil (5-FU) and radiation inhibited the viability of HCT116, HCT116 p53^−/−, and HT29 cells compared to 5-FU or radiation alone. Our findings indicated that IMP1338 induced p53-independent cell death through S and G2/M phase arrest as well as DNA damage. These results provide a basis for future investigations assessing the promising anticancer properties of IMP1338.     

MGN-3/Biobran, modified arabinoxylan from rice bran, sensitizes human breast cancer cells to chemotherapeutic agent, daunorubicin

Background: MGN-3/Biobran, a modified form of arabinoxylan from rice bran, is a potent biological response modifier (BRM). Our previous studies demonstrated that MGN-3 sensitizes human leukemia cells to death receptor [CD95]-induced apoptosis [Ghoneum M, Gollapudi S. MGN-3 sensitizes human T cell leukemia cells to death receptor (CD95)-induced apoptosis. Cancer Lett 2003;201:41-9]. In this study, we evaluated the chemo-sensitizing activity of MGN-3 against human breast cancer cells (BCCs) in vitro. Methods: BCCs (MCF-7 and HCC70 cells) were cultured with different concentrations of daunorubicin (DNR) (from 1 × 10⁻⁹ to 1 × 10⁻⁶ M) in the presence or absence of selected concentrations of MGN-3 (100-1000 μg/ml) for 3 days. Cancer cell survival was determined by MTT assay and drug accumulation was determined by flow cytometry. Results: Treatment with MGN-3 increased susceptibility of BCCs to DNR (5.5-fold for MCF-7 and 2.5-fold for HCC70 cells) as compared to BCCs treated with DNR alone. The sensitizing effect of MGN-3 was associated with increased accumulation of DNR in cancer cells. Conclusions: Our data demonstrate that MGN-3 is an effective chemo-sensitizer and may represent a potential novel adjuvant for the treatment of breast cancer.     

Modulation of multidrug resistance with dexniguldipine hydrochloride (B8509-035) in the CC531 rat colon carcinoma model

The chemosensitizing potency of dexniguldipine hydrochloride (B8509-035) on epidoxorubicin was assessed in a multidrug-resistant (MDR) tumour model, the intrinsic MDR rat colon carcinoma CC531. In vitro in the sulphorhodamine B cell-viability assay the cytotoxicity of epidoxorubicin was increased approximately 15-fold by co-incubation with 50 ng/ml dexniguldipine. In vivo concentrations of dexniguldipine 5 h after a single oral dose of 30 mg/kg were 72 (±19 SD) ng/ml in plasma and 925 (±495 SD) ng/g in tumour tissue. Levels of the metabolite of dexniguldipine, M-1, which has the same chemosensitizing potential, were 26 (±6 SD) ng/ml and 289 (±127 SD) ng/g respectively. The efficacy of treatment with 6 mg/kg epidoxorubicin applied intravenously combined with 30 mg kg^–1 day^–1 dexniguldipine administered orally for 3 days prior to epidoxorubicin injection was evaluated on tumours grown under the renal capsule. Dexniguldipine alone did not show antitumour effects in vivo. Dexniguldipine modestly, but consistently, potentiated the tumour-growth-inhibiting effect of epidoxorubicin, reaching statistical significance in two out of four experiments. In conclusion, these experiments show that dexniguldipine has potency as an MDR reverter in vitro and in vivo in this solid MDR tumour model.Abbreviations MDR multidrug resistance - PBS phosphate-buffered saline