PHⅡ-7通过升高ROS诱导K562和K562/A02凋亡

目的探讨靛玉红衍生物——PHⅡ-7对K562和K562/A02的体外杀伤作用及其机制。方法利用WST-8试剂盒、细胞凋亡检测以及活性氧(ROS)检测研究PHⅡ-7对K562和K562/A02发生杀伤作用的机制。共聚焦显微镜及Western blot分析观察药物处理前后细胞的变化。结果细胞毒实验证实PHⅡ-7对K562和K562/A02有相近的杀伤作用。给予上述两种细胞2μmol·L-1PHⅡ-7可见明显的ROS水平升高。PHⅡ-7对K562及K562/A02具有诱导凋亡的作用,呈剂量依赖性。加入ROS的抑制剂NAC可抑制给药后细胞内ROS水平的提高,同时也抑制了PHⅡ-7处理后细胞的凋亡。共聚焦显微镜观察发现药物处理的K562和K562/A02细胞出现明显的凋亡形态改变,Western blot分析表明单用PHⅡ-7可以引起PARP-1及caspase-3,caspase-9的切割,当PHⅡ-7与NAC共同作用之后,上述改变均被抑制。结论 PHⅡ-7可以通过诱导K562/和K562/A02凋亡来实现对上述细胞的杀伤作用,该作用很有可能与其升高细胞内的ROS水平有关。     

Direct Oral Anticoagulants: New Drugs and New Concepts

Direct oral anticoagulants (DOACs) are approved for multiple thromboembolic disorders and provide advantages over existing agents. As with all anticoagulants, management protocols for the eventuality of bleeding are important. Randomized phase III studies generally show that DOACs have a similar risk of clinically relevant bleeding compared with standard anticoagulants, with reductions in major bleeding in some cases. This may be particularly important in patients with atrial fibrillation, for whom the rate of intracranial hemorrhage was approximately halved with DOACs compared with warfarin. Conversely, the risk of gastrointestinal bleeding may be increased. Specific patient characteristics, such as renal impairment, comedications, and particular aspects of each drug, including the proportion eliminated by the kidneys, must be taken into account when assessing the risk of bleeding. Although routine coagulation monitoring of DOACs is not required, it may be useful under some circumstances. Of the traditional clotting assays, a sensitive and calibrated prothrombin time may be useful for detecting the presence or absence of clinically relevant factor Xa inhibitor concentrations (rivaroxaban or apixaban), but specific anti–factor Xa assays can measure drug levels quantitatively. For dabigatran, the results of an activated partial thromboplastin time test may exclude a clinically relevant pharmacodynamic effect, but a calibrated dilute thrombin time assay can be used for quantification of drug levels. In the event of mild or moderate bleeding, normal hemostatic support measures are recommended. For life-threatening bleeding, use of nonspecific prohemostatic agents may be considered, although clinical evidence is scarce. Specific antidotes are in development.     

穴位埋药线对难治性癫痫大鼠癫痫样波的发放及大脑海马和颞叶皮质多药耐药相关蛋白MRP1、P-gp表达的影响

目的：探讨穴位埋药线对难治性癫痫大鼠癫痫样波的发放及大脑海马和皮质中多药耐药相关蛋白 MRP1、P-gp表达的影响。方法（1）造模：大鼠海马区注射红藻氨酸（KA）,经过点燃和再次亚惊厥剂量点燃造模,且脑电图检测有癫痫样波发放者筛选为造模成功耐药难治性癫痫模型鼠。（2）分组与处理：普通线组（PTX组）与药线组（YX组）,先埋一侧穴位,间隔15 d后埋对侧穴位。拉莫三嗪组（LTG组）按照人用拉莫三嗪剂量换算灌胃大鼠,每日2次;空白对照组（Normal组）和模型组（Model组）给予灌胃同等体积的蒸馏水,均灌胃30 d。（3）采用VEEG-1518K型数字化视频脑电监测分析系统检测脑波基本节律的波幅与频率变化。（4）标本处理与检测：采用免疫组织化学技术,检测多药耐药相关蛋白MRP1、P-gp在海马与颞叶皮层不同部位的表达。结果各组治疗前比较差异无统计学意义（P＞0.05）;各组治疗后,YX组、LTG 组分别与Model 组、PTX组比较差异有统计学意义（P＜0.05）,YX组与LTG组比较差异无统计学意义（P＞0.05）;与Model组相比,LTG组和YX组干预后能降低致痫鼠EEG 痫波放电持续时间与发放频率以及海马区和颞叶皮质区多药耐药蛋白 MRP1、P-gp 的表达水平（P<0.05或P<0.01）;YX组与PTG组比较差异无统计学意义(P<0.05)。结论（1）埋药线使KA致痫鼠EEG痫波放电持续时间缩短,发放频率减少。（2）KA点燃难治性癫痫模型大鼠大脑海马区存在多药耐药蛋白MRP1、P-gp的表达较皮质区明显升高。（3）埋药线逆转与降低致痫鼠海马区多药耐药蛋白MRP1、P-gp的表达水平,可能是其抗癫痫生物学作用机制之一。     

白藜芦醇通过拮抗hPXR对P-gp的影响

目的研究白藜芦醇通过拮抗hPXR对P-gp基因(MDR1)、蛋白表达及活性的影响。方法在LS174T细胞中,采用瞬时共转染报告基因实验研究白藜芦醇对PXR介导的MDR1的转录调节作用,并进一步应用Real-Time定量PCR和Western blot方法检测白藜芦醇作用24 h后对利福平诱导的P-gp基因和蛋白变化的影响,罗丹明转运实验考察P-gp活性的变化。结果双荧光素酶报告基因检测结果显示,25和50μmol.L-1白藜芦醇可通过拮抗PXR将利福平对MDR1的诱导作用由4.70倍分别降至1.76倍和0.69倍(P<0.01),在过表达hPXR的LS174T细胞中,50μmol.L-1白藜芦醇可以将利福平诱导的MDR1 mRNA水平由1.8倍降至1.3倍(P<0.05),Western blot结果表明白藜芦醇也可降低利福平诱导的P-gp表达。此外,罗丹明转运实验显示,25和50μmol.L-1白藜芦醇可以将利福平抑制的累积量由77.7%升至91.7%和95.1%(P<0.05),表明白藜芦醇可降低利福平诱导的P-gp活性。结论白藜芦醇可以通过拮抗PXR而影响P-gp的基因、蛋白表达及活性。     

柚皮苷逆转人卵巢癌耐药SKOV3／DDP细胞耐药性及逆转机制的研究

目的 研究柚皮苷对卵巢癌顺铂（DDP）耐药细胞SKOV3／DDP体外增殖的影响及耐药逆转作用,并初步探讨相关耐药机制。方法采用MTT法测定DDP对SKOV3和SKOV3／DDP细胞的半数抑制浓度（IC₅₀）,柚皮苷对SKOV3／DDP细胞的增殖抑制作用及柚皮苷联合DDP对SKOV3／DDP细胞的增殖抑制作用。筛选出非细胞毒性的柚皮苷浓度,将实验细胞分为空白对照组、2.5 μg／ml DDP组、10 μmol/L柚皮苷组、10 μmol/L柚皮苷联合2.5 μg／ml DDP组,分别采用RT-PCR和Western blotting测定各组作用48 h后耐药基因MDR1 mRNA及MRP2 mRNA的表达及其相应的表达产物P-gp、MRP2蛋白的表达水平。结果1～32 μg／ml DDP处理SKOV3及SKOV3／DDP细胞48 h后,SKOV3细胞的IC₅₀为5.48 μg／ml,SKOV3／DDP细胞为14.93 μg／ml,耐药指数为2.72。柚皮苷对SKOV3／DDP细胞有明显的增殖抑制作用,且呈剂量和时间依赖性。选取10 μmol／L柚皮苷作为逆转耐药实验浓度,10 μmol／L柚皮苷联合DDP作用48 h后,SKOV3／DDP细胞对DDP的耐药指数为1.62,逆转倍数为1.68。RT-PCR及Western blotting检测显示,柚皮苷联合DDP组与DDP单药组比较,MDR1 mRNA、MRP2 mRNA表达及P-gp、MRP2蛋白表达均明显下降,差异有统计学意义（P＜0.05）。结论柚皮苷对卵巢癌SKOV3／DDP细胞的体外增殖具有明显抑制作用,并能逆转SKOV3／DDP细胞的耐药性,其逆转耐药的机制可能与下调耐药基因MDR1 mRNA及MRP2 mRNA及相应的P-pg、MRP2蛋白的表达有关。     

ZNF300基因在肝癌耐药细胞HepG2/VCR中的表达及功能初探

目的建立人肝癌HepG2/VCR耐药细胞株,检测ZNF300基因在HepG2/VCR中的表达并初步分析其在肝癌多药耐药(MDR)中发挥的功能。方法采用体外低浓度梯度递增的诱导方法建立长春新碱(VCR)获得性HepG2/VCR耐药细胞株。MTT法检测确定HepG2/VCR耐药细胞株对VCR的耐药性,用Western blot方法检测人锌指蛋白ZNF300基因编码的ZNF300及多药耐药基因编码的P糖蛋白(P-gp)在HepG2和HepG2/VCR细胞中的表达差异;在HepG2/VCR细胞中转染ZNF300基因正向或反向cDNA质粒后,MTT法检测VCR对耐药细胞IC50值的变化,Westernblot方法检测细胞内P-gp表达的影响。结果 MTT检测确认HepG2/VCR耐药细胞构建成功,Western blot检测发现耐药细胞中ZNF300及P-gp的表达相对于HepG2细胞明显增高。在HepG2/VCR细胞中转染正向ZNF300 cDNA质粒后,MTT和Western blot检测发现ZNF300过表达可使VCR对耐药细胞的IC50值增高,并使细胞内P-gp表达上调;在转染反向cDNA质粒Knockdown ZNF300基因表达后得到相反的结果。结论 ZNF300基因在HepG2/VCR耐药细胞中表达明显增高,并能通过上调耐药蛋白P-gp的表达促进肝癌细胞耐药性,可以作为逆转肝癌多药耐药的分子作用靶点。     

Mitochondrial autophagosomes as a mechanism of drug resistance in breast carcinoma

We have previously described the process by which mitochondria donate their membranes for the formation of autophagosomes, and in this study we show that the same process could be involved in drug sequestration and exocytosis resulting in multidrug-resistant cancerous cells. We examine the implications of mitochondrial vesicle formation of mitoautophagosomes (MAPS) in response to the cytotoxic drug MKT-077, which targets mortalin, in a drug-resistant breast carcinoma cell line overexpressing P-glycoprotein (P-gp). The breast cancer cell line MCF-7Adr is derived from MCF-7, but differs from its ancestral line in tolerance of MKT-077-induced mitochondrial toxicity. Our ultrastructural observations suggest that autophagy in the MCF-7Adr cells entails regional sequestration of MKT077 in multilamellar LC3-labeled MAPS, which then separate from their mitochondria, and fuse with or engulf each other. MAPS appeared to be migrating through the cytoplasm and fusing with the plasma membrane, thus carrying out exocytotic secretion. This mechanism, which seems ineffective in the ancestral cell line, provides a resistance mechanism for MKT-077 by enhancing the efflux process of the cells. After 8 hr of MKT-077 exposure, a fraction of the resistant cells appeared viable and contained larger number of smaller sized mitochondria. Mitoautophagosomes, therefore, provide a potentially novel model for multidrug resistance in cancerous cells and may contribute to the P-gp efflux process.     

Temozolomide resistance in glioblastoma occurs by miRNA-9-targeted PTCH1, independent of sonic hedgehog level

Glioblastoma Multiforme (GBM), the most common and lethal adult primary tumor of the brain, showed a link between Sonic Hedgehog (SHH) pathway in the resistance to temozolomide (TMZ). PTCH1, the SHH receptor, can tonically represses signaling by endocytosis. We asked how the decrease in PTCH1 in GBM cells could lead to TMZ-resistance. TMZ resistant GBM cells have increased PTCH1 mRNA and reduced protein. Knockdown of Dicer, a Type III RNAase, indicated that miRNAs can explain the decreased PTCH1 in TMZ resistant cells. Computational studies, real-time PCR, reporter gene studies, western blots, target protector oligos and ectopic expression identified miR-9 as the target of PTCH1 in resistant GBM cells with concomitant activation of SHH signaling. MiR-9 mediated increases in the drug efflux transporters, MDR1 and ABCG2. MiR-9 was increased in the tissues from GBM patients and in an early passage GBM cell line from a patient with recurrent GBM but not from a naïve patient. Pharmacological inhibition of SHH signaling sensitized the GBM cells to TMZ. Taken together, miR-9 targets PTCH1 in GBM cells by a SHH-independent method in GBM cells for TMZ resistance. The identified pathways could lead to new strategies to target GBM with combinations of drugs.     

Cbl-b inhibits P-gp transporter function by preventing its translocation into caveolae in multiple drug-resistant gastric and breast cancers

The transport function of P-glycoprotein (P-gp) requires its efficient localization to caveolae, a subset of lipid rafts, and disruption of caveolae suppresses P-gp transport function. However, the regulatory molecules involved in the translocation of P-gp into caveolae remain unknown. In the present study, we showed that c-Src dependent Caveolin-1 phosphorylation promoted the translocation of P-gp into caveolae, resulting in multidrug resistance in adriamycin resistant gastric cancer SGC7901/Adr and breast cancer MCF-7/Adr cells. In a negative feedback loop, the translocation of Cbl-b from the nucleus to the cytoplasm prevented the localization of P-gp to caveolae resulting in the reversal of MDR through the ubiquitination and degradation of c-Src. Clinical data showed a significant positive relationship between Cbl-b expression and survival in P-gp positive breast cancer patients who received anthracycline-based chemotherapy. Our findings identified a new regulatory mechanism of P-gp transport function in multiple drug-resistant gastric and breast cancers.     

分割剂量电离辐射对卵巢癌细胞多药耐药的影响

目的 研究不同分割剂量电离辐射方案对卵巢癌细胞多药耐药性的影响.方法 采用卵巢癌亲本细胞SKOV3及其耐药细胞株SKVCR,分别进行假照射、单次照射(10 Gy)、常规分割照射(2 Gy ×5)和超分割照射(1 Gy×2 ×5).MTT方法检测细胞对4种化疗药物硫酸长春新碱( vincristine,VCR)、依托泊苷(etoposide,VP-16)、盐酸吡柔比星(pirarubicin,THP)和顺铂(cisplatin,DDP)敏感性的变化.Western blot检测P-gp蛋白表达量.结果 与SKOV3相比,SKVCR倍增时间增加为1.8倍,P-gp糖蛋白表达增高,4种药物对SKVCR的IC50浓度明显增加(P＜0.05).在SKOV3中,与假照组相比,单次照射后细胞对THP、DDP药敏性降低,常规分割照射后细胞对VCR、THP、VP-16药敏性降低,超分割照射使VP-16药敏性降低;在SKVCR中,与假照组相比,3个照射组对VCR、VP-16的药敏性增高,对DDP的药敏性无明显改变,单次和分割照射均可降低P-gp表达.结论 单次、分割和超分割照射在SKOV3亲本细胞中诱导多药耐药,在耐药株SKVCR中逆转对VCR、VP-16的耐药性.