灵芝多糖肽对Caco-2细胞上P糖蛋白功能、表达的影响

目的 研究灵芝多糖肽(ganoderma lucidum polysaccharides peptide,GLPP)对Caco-2细胞P糖蛋白(P-gp)功能和表达的影响.方法 用流式细胞仪测定Caco-2细胞中P-gp底物罗丹明123和抗体的荧光强度,分析药物对P-gp功能和表达的影响.双向跨膜转运实验考查GLPP对罗丹明123转运的影响.结果 10、20、50、100μg·mL-1的GLPP均抑制了Rh-123的外排,其外排分别降低了8％、16％、19％、33％,具有浓度依赖性.高、中浓度的GLPP(50、100 μg·mL-1)对Rh-123的双向转运有一定的抑制,外排率(ER)较阴性对照组降低了15％、18％.细胞与药物作用72 h后,细胞抗体荧光强度降低,P-gp的表达降低.结论 GLPP对P-gp的活性有一定的抑制作用,能在较短的时间内增加细胞内Rh-123的蓄积,抑制Rh-123的双向转运.长期使用GLPP可抑制P-gp的表达.     

野黄芩苷对Caco-2细胞中P-gp蛋白表达及活性的影响

目的:研究野黄芩苷对Caco-2细胞中P-糖蛋白(P-gp)表达及活性的影响。方法:野黄芩苷(25,50及100μmol·L-1)与Caco-2细胞共孵育24 h,48 h及72 h后,通过western blot方法检测野黄芩苷对Caco-2细胞中P-gp蛋白表达的影响;通过罗丹明123转运试验,测定罗丹明123在Caco-2细胞内的累积量变化,以考察野黄芩苷对P-gp活性的影响。结果:野黄芩苷对Caco-2细胞中P-gp蛋白表达具有诱导作用,孵育24 h后,野黄芩苷(25,50及100μmol·L-1)对P-gp蛋白的上调倍数分别为2.34,2.65,2.00;孵育48 h后,野黄芩苷上调P-gp蛋白表达2.70,4.66,3.13倍;孵育72 h后,野黄芩苷(25,50及100μmol·L-1)对P-gp蛋白的上调倍数分别为2.82,2.62,1.84。野黄芩苷上调Caco-2细胞中P-gp蛋白表达的同时增加P-gp外排泵活性,孵育24 h后,野黄芩苷(25,50及100μmol·L-1)降低胞内罗丹明123累积量至70.6%,66.6%,76.6%;孵育48 h后,胞内罗丹明123累积量降低至55.6%,37.5%,65.2%;孵育72 h后,胞内罗丹明123累积量降低至45.5%,53.9%,60.3%。结论:野黄芩苷诱导Caco-2细胞中P-gp的蛋白表达,并能增加P-gp外排泵活性。     

当归水提物对Caco-2细胞ABCB1蛋白功能调节效应的体外机制研究

目的探讨当归水提物及其活性成分阿魏酸（FA）对Caco-2细胞上的ABCB1蛋白摄取功能的影响。方法采用MTT法确定药物实验剂量,利用流式细胞术检测Caco-2细胞内ABCB1蛋白底物罗丹-明123（Rh-123）的荧光强度。结果由MTT法得到当归水提物和FA的浓度＆lt;100 mg.L-1时,细胞的存活率＆gt;90%;流式仪检测到中、高浓度的当归水提物和FA（10、100 mg.L-1）与Caco-2细胞孵育60 min后,分别能够使细胞内Rh-123的荧光强度减少27%、10%。结论当归水提物对ABCB1蛋白介导的Rh-123的外排有一定的诱导作用,并在一定范围内具有浓度依赖性,药物浓度越高,诱导作用越强。其活性成分FA对ABCB1蛋白只有轻微地诱导作用。     

Caco-2细胞模型研究白芷提取物对P-糖蛋白功能的影响

目的:研究白芷提取物对黄酮类成分葛根素、黄芩苷肠道转运的影响,结合白芷提取物对Caco-2细胞上P-gp功能的影响,探讨白芷提取物对葛根素、黄芩苷肠吸收的影响机制。方法:采用Caco-2细胞模型,研究白芷提取物分别对黄酮类成分葛根素、黄芩苷吸收的影响,以P-gp底物罗丹明123(R-123)为荧光探针,评价不同浓度白芷提取物和P-gp抑制剂维拉帕米对R-123细胞蓄积的影响,细胞内的R-123浓度采用荧光分光光度法检测。结果:白芷提取物对葛根中葛根素、黄芩中黄芩苷的吸收均有明显的促进作用,葛根素的表观渗透系数Papp分别提高1.6～3.6倍,黄芩苷的表观渗透系数Papp分别提高2.3～3.3倍;白芷香豆素(0.15～1.5 mg.mL-1)、白芷挥发油(0.24～6.0μL.mL-1)、白芷香豆素+白芷挥发油均能显著增加细胞内Rh-123的摄取,对P-gp显示出明显剂量依赖性的抑制作用。结论:白芷提取物促进葛根素、黄芩苷等黄酮类成分吸收的原因可能与其抑制P-gp外排有关。     

姜黄素对Caco-2细胞上P-糖蛋白活力及MDR1 mRNA表达的影响

目的研究姜黄素对Caco-2细胞上P-糖蛋白(P-gp)功能和表达的影响,并从分子水平研究其对MDR1mRNA表达的影响。方法采用流式细胞仪测定P-gp底物——罗丹明-123在细胞中的浓度,并分析Caco-2细胞上P-糖蛋白的表达量;采用RT-PCR法分析Caco-2细胞上MDR1基因mRNA的表达量。结果低、中、高浓度(0.1、0.5、1.0μmol.L-1)的姜黄素增加了罗丹明-123的外排,其外排量分别增加了6.2%、22.2%和33.8%(P<0.05);0.1～1.0μmol.L-1姜黄素与细胞孵育72h后,细胞膜上的荧光强度随浓度增加而增强(P<0.05),P-gp表达量是空白对照组的4倍,MDR1基因mRNA表达水平上调了1.58倍。结论姜黄素并不是P-gp的抑制剂,它能在较低浓度以及较短时间内(1h)增强Caco-2细胞上P-gp的功能活性,从而减少罗丹明-123在细胞内的蓄积。长时间(72h)应用姜黄素可以诱导P-gp和MDR1mRNA的表达。姜黄素将有可能引起相应的药物-药物/食物的相互作用。     

低剂量甲基强的松龙诱导淋巴细胞糖皮质激素耐药与P-糖蛋白关系的研究

目的 研究低剂量甲基强的松龙(糖皮质激素)诱导淋巴细胞糖皮质激素耐药与P-糖蛋白的关系.方法 取健康人外周血,分离纯化淋巴细胞,予小剂量(2μg·mL-1)甲基强的松龙刺激72 h为耐药组,对照组常规培养;用流式细胞术检测P-gp表达;MTT法检测激素耐药倍数;甲基强的松龙(200μg·mL-1)刺激2组细胞24 h,用流式细胞术检测Annexin V(%)并分析P-gp与其相关性;耐药组,用5 μg·mL-1维拉帕米联合甲基强的松龙(200 μg·mL-1)刺激,检测Annexin V(%).结果 小剂量甲基强的松龙诱导后的淋巴细胞P-gp表达,耐药组较对照组显著升高,为对照组的(2.89±0.21)倍;甲基强的松龙刺激后,耐药组细胞凋亡率显著低于正常组,与Annexin V呈显著负相关;维拉帕米干预可显著增加甲基强的松龙诱导细胞凋亡的敏感性.结论 P-gp介导耐药可能是导致临床治疗后期的耐药或药物依赖的重要机制之一.     

芝麻素协同吉西他滨对人肺腺癌A-549细胞株的作用

目的观察芝麻素及联合吉西他滨对人肺腺癌A-549细胞株的作用。方法体外培养A-549细胞株。MTT法检测细胞增殖,Hoechst33258荧光染色法观察细胞形态学变化,流式细胞术检测细胞内Ca2+浓度变化,免疫细胞化学法观察caspase-3、caspase-8和caspase-9的表达。结果 20⁸0μg·mL-1芝麻素对A-549细胞均有一定的增殖抑制作用(P<0.01),而随着浓度增加,至70μg·mL-1时,增殖抑制作用逐渐减弱,IC50浓度为40μg·mL-1。0.00180μg·mL-1芝麻素对A-549细胞均有一定的增殖抑制作用(P<0.01),而随着浓度增加,至70μg·mL-1时,增殖抑制作用逐渐减弱,IC50浓度为40μg·mL-1。0.001²0μg·mL-1吉西他滨对A-549细胞的生长均具有抑制作用(P<0.01),且呈现浓度依赖性,IC50浓度为1.0μg·mL-1;40μg·mL-1芝麻素+1.0μg·mL-1吉西他滨组的增殖抑制作用更为显著(P<0.01)。40μg·mL-1芝麻素组、1.0μg·mL-1吉西他滨组和芝麻素+吉西他滨组作用A-549细胞48 h后在荧光染色荧光显微镜下观察发现受抑制细胞核浓缩,细胞核染色质高度凝聚、边缘化,与对照组相比细胞内Ca2+浓度水平增高,caspase-3、caspase-8和caspase-9表达均显著增加(P<0.05),联用组均显著高于两药单用组(P<0.01)。结论芝麻素联合吉西他滨可协同抑制A-549细胞,其机制可能与提高细胞浆内Ca2+浓度进而诱导细胞凋亡,激活caspase通路有关。     

黄芪多糖对MIN6细胞增殖、凋亡及胰岛素分泌的影响

目的:研究不同浓度黄芪多糖(Astragalus polysaccharide,APS)对胰岛MIN6细胞的增殖活性、细胞凋亡及胰岛分泌功能的影响。方法:用不同浓度APS(0,10,100和1 000μg.mL-1)干预MIN6细胞48 h,采用MTT法测细胞增殖活性,流式细胞仪检测细胞凋亡,分别用3和30 mmol.L-1葡萄糖刺激各组MIN6细胞,胰岛素放免试剂盒检测胰岛素分泌功能。结果:与对照组(0μg.mL-1)比较,100μg.mL-1 APS组MIN6细胞增殖活性升高(P<0.05);10和100μg.mL-1 APS组MIN6细胞凋亡率有下降趋势,而1 000μg.mL-1 APS组MIN6细胞凋亡率明显增加(P<0.05);10和100μg.mL-1 APS组MIN6细胞胰岛素分泌功能显著增强(P<0.05),而1 000μg.mL-1 APS组MIN6细胞胰岛素分泌功能有下降趋势。结论:10和100μg.mL-1 APS使MIN6细胞增殖活性升高、细胞凋亡率下降以及胰岛素分泌功能升高;1 000μg.mL-1 APS使MIN6细胞增殖活性下降、细胞凋亡率升高及胰岛素分泌功能下降。     

盐酸度洛西汀对Caco-2细胞P-糖蛋白功能及表达的影响

目的 研究盐酸度洛西汀(DLX)对Caco-2细胞上P-糖蛋白(P-gp)功能和表达的影响.方法 将Caco-2细胞分为阴性对照组、维拉帕米10 μmol/L阳性对照组(VER组)和DLX 0.2、5、10 μmol/L不同浓度处理组.采用流式细胞术检测DLX干预后Caco-2细胞内罗丹明-123的荧光强度和细胞膜上P-gP的表达量.结果 与阴性对照组相比,DLX 0.2、5、10 μmol/L均显著抑制罗丹明-123从Caco-2细胞的外排(96.3±4.5 vs.129.5±14.5、131.2±7.0、135.6±17.1)(P＜0.05),而对P-gp阳性率无明显改变(90％ vs.94％、91％、89％)(P＞0.05).结论 DLX能抑制Caco-2细胞上P-gp的功能,降低罗丹明-123从Caco-2细胞中的外排,但并不影响P-gp的表达.     

川芎嗪对Caco-2细胞p-糖蛋白功能和表达的影响

目的研究川芎嗪对和Caco-2细胞p-糖蛋白功能和表达的影响。方法用p-糖蛋白底物罗丹明123在细胞外排和转运的改变指示细胞膜上p-糖蛋功能的改变,流式细胞仪分析Caco-2细胞膜上p-糖蛋白表达量的变化。结果中、高浓度(120、240μg.mL-1)的川芎嗪能够使罗丹明123从Caco-2细胞的外排量分别减少2.67倍和9.08倍,与细胞孵育72 h后能够使Caco-2细胞表面p-糖蛋白的表达水平下调46.4%和61.2%,在1.5 h使罗丹明123在Transwell的BL侧的累积排放量增加了1.3倍和1.8倍。结论川芎嗪可以显著减小罗丹明123在Caco-2细胞的外排,对罗丹明123跨细胞膜转运也有显著影响。将川芎嗪与Caco-2细胞共同培养72 h后,川芎嗪能够显著降低Caco-2细胞上p-糖蛋白的表达。川芎嗪与p-糖蛋白底物共同应用时要注意发生由p-糖蛋白介导的药物相互作用,川芎嗪可能是一种很有前途的多药耐药逆转剂。     

Effects of benzo(e)pyrene and benzo(a)pyrene on P-glycoprotein-mediated transport in Caco-2 cell monolayer: a comparative approach.

The previous studies from our laboratory reported that benzo(a)pyrene (Bap) influenced efflux transport of rhodamine 123 (Rho-123) by induction of P-glycoprotein (P-gp) in Caco-2 cells. The present study investigated whether induction of P-gp and the enhanced efflux transport of Rho-123 were caused by benzo(e)pyrene (Bep), which has a structure similar to Bap, but is not a carcinogenic compound. In Caco-2 monolayer exposed to 50 microM Bep for 72 h, the ratio of the apparent permeability coefficient (P(app)) of Rho-123 efflux increased significantly compared to that of the control monolayer. Similarly, a significant increase in expression of MDR1 mRNA and of P-gp at the protein level were detected by RT-PCR and by Western blot analysis, respectively, in Caco-2 cells exposed to Bep, compared to that of the control. Caco-2 cells exposed to Bep showed oxidative stress that was detected by fluorescence microscopy using aminophenyl fluorescein. However, the oxidative stress was weaker compared with that of Bap. The cellular GSH content was decreased to 80% or 59% of control cells, respectively, in Caco-2 cells exposed to either Bep or Bap. Our results further show that Bep or Bap-induced P-gp in Caco-2 cells might have been the result of oxidative stress rather than DNA damage.     

Induction of human P-glycoprotein in Caco-2 cells: development of a highly sensitive assay system for P-glycoprotein-mediated drug transport

The aim of this work is to develop a highly sensitive assay system for P-gp-mediated transport by using two methods, induction of P-gp and short-term culture of Caco-2 cells. To induce P-gp in Caco-2 cells, cells were cultured in vinblastine-containing medium. The mRNA level of P-gp was approximately 7-fold higher in Caco-2 cells cultured with vinblastine (P-gp-induced Caco-2 cells) than in control cells. Western blot analysis showed a significant increase in P-gp expression. After cell differentiation, the mRNA level of P-gp was downregulated, however, P-gp-induced Caco-2 cells still possessed a 5.6-fold higher mRNA level of P-gp compared to control cells. Polarized transport of substrate drugs was greater in the monolayer of P-gp-induced cells than in that of control cells. Moreover, we found that P-gp expression in Caco-2 cells could be further enhanced by applying the higher concentration of vinblastine. Transport activity of P-gp in Caco-2 cells cultured with higher concentration of vinblastine was markedly higher than that in P-gp-induced Caco-2 cells and was comparable with that in MDR1-MDCKII cells. In conclusion, this study provided a stable and highly sensitive in vitro assay system that can identify compounds that are subject to P-gp-mediated efflux.     

洛美利嗪对大鼠脑微血管内皮细胞上P-糖蛋白活力的影响与P-gp及mdr1基因mRNA表达无关

目的：研究洛美利嗪对原代培养的大鼠脑微血管内皮细胞（RBMECs）上P-糖蛋白（P-gP）功能和表达的影响。方法：使用流式细胞术分析洛美利嗪对P-gp底物-罗丹明123（rhodaminel23，Rh123）在RBMECs中外排的影响，使用流式细胞术分析了洛美利嗪对RBMECs上P-gp表达的影响，应用RT-PCR技术分析了洛美利嗪对RBMECs mdr1基因mRNA水平表达的影响，还使用Transwell模型研究了洛美利嗪对Rh123通透RBMECs单层细胞转运的影响。结果：洛美利嗪通过抑制了RBMECs胞内Rh123的外排；洛美利嗪对P—gP功能的影响与RBMECs上P-gp及mdr1基因mRNA表达无关；在Transwell模型中，洛美利嗪还能显著增加Rh123跨RBMECs单层细胞膜的、经上室至下室的转运，并抑制相反方向的Rh123的转运。结论：洛美利嗪能显著地抑制RBMECs上P-gp的活性，并对P-gp底物的跨细胞转运产生影响。     

Effects of capsaicin on cellular damage and monolayer permeability in human intestinal Caco-2 cells

Recent studies suggest that capsaicin (Cap), a major constituent of hot pepper, may affect the function and permeability of the intestinal mucosa in vitro. However, the relationships between the dose of Cap and the barrier and/or transporter functions on intestinal epithelial cells are unknown. The aim of this study was to investigate whether Cap initiates cellular injury and alter epithelial permeability in Caco-2 cells. Cellular toxicity, as measured using a lactate dehydrogenase release assay, was not observed at high concentrations of Cap (up to 300 microM). When cell viability was measured by a WST-1 assay (tetrazolium salt-based assay), damage to Caco-2 monolayers was observed at doses of 200 and 300 microM of Cap. The barrier function of tight junctions was assessed by measuring transepithelial electrical resistance (TEER) in Caco-2 cells. Treatment of Caco-2 cells with Cap at doses above 100 microM significantly decreased the TEER compared to treatment with buffer alone for 2 h (p<0.05). We next examined the effects of Cap on the activity of P-glycoprotein (P-gp) found on transcellular transporters. At doses of 100 and 200 microM, Cap inhibited the transport of rhodamine 123 by P-gp-mediated efflux in Caco-2 cells. Cap thus exhibited inhibitory effects on P-gp. The results of this study indicate that Cap, a dietary phytochemical, causes functional and structural changes in Caco-2 cell monolayers at noncytotoxic doses (less than 100 microM of Cap). The concomitant administration of Cap with drugs that are substrates of P-gp might increase the plasma concentrations of such drugs.     

Effect of benzo[a]pyrene on P-glycoprotein-mediated transport in Caco-2 cell monolayer

The main exposure pathway of benzo[a]pyrene (Bap) for humans is considered to be via the daily diet. The purpose of this study was to investigate the effect of BaP on the intestinal transport of chemicals mediated by P-glycoprotein (P-gp). The intestinal epithelial membrane transport of rhodamine-123 (Rho-123), a substrate of P-gp, was examined using a monolayer of the human Caco-2 cell line grown in transwells. In the monolayer exposed to Bap for 72 h before transport experiments, the ratio of the apparent permeability coefficients (P(app)) of Rho-123 efflux increased compared to that of the control. The permeability of rhodamine-B (Rho-B), not a substrate of P-gp, showed no difference between the monolayers. Treatment with quinidine or cyclosporine A, which are P-gp inhibitors, decreased the P(app) of Rho-123 to the same degree in both monolayers. The transport of Rho-123 was not influenced by the presence of Bap. Thus, Bap seemed not to act directly on the efflux activity of P-gp and be a binding site competitor of Rho-123. In the Caco-2 cells that enhanced the efflux of Rho-123 by the treatment with Bap, an increase in mRNA expression of MDR 1 (P-gp) was confirmed compared to that of control by RT-PCR. Furthermore, Western blot analysis using a monoclonal antibody, C219, demonstrated the increase of P-gp in Caco-2 cells exposed to Bap, compared with controls. It was inferred that Bap exposure induced the expression of P-gp, which led to the observed increase in efflux transport of Rho-123. The possibility was suggested that Bap might affect the disposition of medicines by increasing P-gp expression.     

Saikosaponin A,an active glycoside from Radix bupleuri,reverses P-glycoprotein-mediated multidrug resistance in MCF-7/ADR cells and HepG2/ADM cells

1.?The expression and function of P-glycoprotein (P-gp) is associated with the phenotype of multidrug resistance (MDR). Saikosaponin A (SSA) is a triterpenoid saponin isolated from Radix Bupleuri. This study was mainly designed to understand effects of SSA on MDR in MCF-7/ADR and HepG2/ADM cells.

2.?MDR reversal was examined as the alteration of cytotoxic drugs IC50 in resistant cells in the presence of SSA by MTT assay, and was compared with the non-resistant cells. Apoptosis and uptake of P-gp substrates in the tumor cells were detected by flow cytometry. Western blot was performed to assay the expression of P-gp.

3.?Our results demonstrate SSA could increase the chemosensitivity of P-gp overexpressing HepG2/ADM and MCF-7/ADR cells to doxorubicin (DOX), vincristine (VCR) and paclitaxel. SSA promoted apoptosis of MCF-7/ADR cells in the presence of DOX. Moreover, it could also increase the retention of P-gp substrates DOX and rhodamine 123 in MCF-7/ADR cells, and decrease digoxin efflux ratio in Caco-2 cell monolayer. Finally, a mechanistic study showed that SSA reduced P-gp expression without affecting hydrolytic activity of P-gp.

4.?In conclusion, our findings suggest that SSA could be further developed for sensitizing resistant cancer cells and used as an adjuvant therapy together with anticancer drugs to improve their therapeutic efficacies.