Combinatory antitumor therapy by cascade targeting of a single drug

Combination therapy has shown its promise in the clinic for enhancing the efficacy of tumor treatment. However, the dose control of multiple drugs and their non-overlapping toxicity from different drugs are still great challenge. In this work, a single model drug, paclitaxel (PTX), is used to realize combination therapy and solve the problems mentioned above. Either PTX or its triphenylphosphine derivative (TPTX) is encapsulated in galactose-modified liposomes (GLips) to obtain GLips-P or GLips-TP, which are simply mixed in different ratios to finely control the proportion of PTX and TPTX. These mixed liposomes, GLips-P/TP, feature a cascade target delivery of PTX, from tissue to cell, and then to organelle. PTX plays a primary role to cause the cytotoxicity by microtubule bindings in cytoplasm, while TPTX is proved to increase the intracellular levels of caspase-3 and caspase-9 that cause apoptosis via a mitochondria-mediated pathway. Notably, GLips-P/TP 3:1 exhibited the significant drug synergy in both cytotoxicity assay of HepG2 cells and the treatment efficacy in Heps xenograft ICR mouse models. This work not only demonstrates the great promise of a cascade targeting delivery for precise tumor treatment, but also offers a novel platform to design combinatory therapy systems using a single drug.     

Potentiation of PIEZO2 mechanically-activated currents in sensory neurons mediates vincristine-induced mechanical hypersensitivity

Vincristine, a widely used chemotherapeutic agent for treating different cancer, often induces severe peripheral neuropathic pain. A common symptom of vincristine-induced peripheral neuropathic pain is mechanical allodynia and hyperalgesia. However, mechanisms underlying vincristine-induced mechanical allodynia and hyperalgesia are not well understood. In the present study, we show with behavioral assessment in rats that vincristine induces mechanical allodynia and hyperalgesia in a PIEZO2 channel-dependent manner since gene knockdown or pharmacological inhibition of PIEZO2 channels alleviates vincristine-induced mechanical hypersensitivity. Electrophysiological results show that vincristine potentiates PIEZO2 rapidly adapting (RA) mechanically-activated (MA) currents in rat dorsal root ganglion (DRG) neurons. We have found that vincristine-induced potentiation of PIEZO2 MA currents is due to the enhancement of static plasma membrane tension (SPMT) of these cells following vincristine treatment. Reducing SPMT of DRG neurons by cytochalasin D (CD), a disruptor of the actin filament, abolishes vincristine-induced potentiation of PIEZO2 MA currents, and suppresses vincristine-induced mechanical hypersensitivity in rats. Collectively, enhancing SPMT and subsequently potentiating PIEZO2 MA currents in primary afferent neurons may be an underlying mechanism responsible for vincristine-induced mechanical allodynia and hyperalgesia in rats. Targeting to inhibit PIEZO2 channels may be an effective analgesic method to attenuate vincristine-induced mechanical hypersensitivity.     

微管微创人工流产术终止妊娠的临床观察

目的观察微管微创人工流产术终止妊娠的疗效。方法将本院2010年1月至2013年9月收治的行人工流产术的孕妇120例根据人工流产方式不同分为传统手术组和微管微创手术组,每组各60例。微管微创手术组孕妇行微管微创人工流产术,传统手术组孕妇行传统负压吸宫术。观察两组孕妇术后疼痛情况、手术时间、术中出血量、疗效及阴道流血时间。结果微管微创手术组孕妇1级疼痛者多于传统手术组,2、3级疼痛者较传统手术组少,手术时间、术中出血量均明显少于传统手术组,差异均具有显著性(P<0.05)。两组孕妇均完全流产,微管微创手术组孕妇术后阴道出血时间为(4.3±2.9)分钟,传统手术组为(7.8±2.9)分钟,两组比较差异具有显著性(t=18.61,P<0.05)。结论微管微创人工流产术较传统负压吸宫术,孕妇痛苦小,出血量少,流产成功率高,是终止早期妊娠的理想选择方案。     

Palytoxins and cytoskeleton: An overview

Cytoskeleton is a dynamic structure essential for a wide variety of normal cellular processes, including the maintenance of cell shape and morphology, volume regulation, membrane dynamics and signal transduction. Cytoskeleton is organized into microtubules, actin meshwork and intermediate filaments. Actin has been identified as a major target for destruction during apoptosis and is also important under pathological conditions such as cancers.Several natural compounds actively modulate actin organization by specific signaling cascades being useful tools to study cytoskeleton dynamics.Palytoxin is a large bioactive compound, first isolated from zoanthids, with a complex structure and different analogs such as ostreocin-D or ovatoxin-a. This toxin has been identified as a potent tumor promoter and cytotoxic molecule, which leads to actin filament distortion and triggers cell death or apoptosis. In this review we report the findings on the involvement of palytoxin and analogues modulating the actin cytoskeleton within different cellular models.     

Taccalonolides: Novel microtubule stabilizers with clinical potential

Nature remains an important source for new anticancer drugs. Numerous microtubule-targeting agents currently approved or in clinical development, including paclitaxel, vinblastine, vincristine, colchicine and combretastatin, are plant-derived compounds. The microtubule stabilizing properties of the taccalonolides were discovered as a part of a program to identify new microtubule stabilizers from natural sources. The taccalonolides are unique among all other agents in this class in that they stabilize microtubules through a mechanism of action that does not involve direct tubulin binding. Herein we review the discovery and isolation of the taccalonolides, their biological activities in vitro and in vivo and their potential advantages over clinically used microtubule stabilizers. We also discuss the challenges in formulation and supply that will need to be solved before the taccalonolides can become candidates for clinical development.     

AcMNPV EXON0 (AC141) which is required for the efficient egress of budded virus nucleocapsids interacts with β-tubulin

The Autographa californica multiple nucleopolyhedrovirus (AcMNPV) encoded protein, EXON0 (AC141), is required for the efficient transport of nucleocapsids out of the nucleus for the production of budded virus (BV). To further elucidate the molecular mechanisms by which EXON0 regulates BV production, EXON0 was tagged at the N-terminus with 3× FLAG-6× His. Protein complexes were isolated by tandem affinity purification and potential EXON0 specific interacting protein partners were gel purified and identified by LC-MS/MS. This analysis showed that the cellular protein, β-tubulin, co-purified with EXON0 which was confirmed by co-immunoprecipitation. In addition, immunofluorescence showed that EXON0 and β-tubulin co-localized during virus infection. The microtubule inhibitors colchicine and nocodazole were used to treat AcMNPV infected Sf9 cells and results showed that BV production was reduced by over 85%. These data suggest that the egress of AcMNPV budded virus may be facilitated by the interaction of EXON0 with β-tubulin and microtubules.     

慢性不可预见性温和应激后大鼠行为及海马细胞支架的改变

目的研究慢性不可预见性温和应激所致的动物行为学改变及细胞支架微管系统的动态性改变。方法将大鼠随机分为应激模型组（8只,以下简称模型组）和对照组（8只）,对模型组大鼠进行连续21d的慢性不可预见性应激。进行行为学观察,使用western blotting检测乙酰化微管蛋白（Acet—Tub）,酪氨酸微管蛋白（Tyr—Tub）。结果（1）模型组大鼠慢性应激后糖水偏好及自主活动显著减低,与对照组有显著差异;（2）模型组大鼠慢性应激后海马Acet—Tub表达升高,Tyr—Tub表达减低,与对照组有显著差异。结论慢性应激后微管动态性减低,神经可塑性受损。     

Indicine N-oxide binds to tubulin at a distinct site and inhibits the assembly of microtubules: A mechanism for its cytotoxic activity

Indicine N-oxide, a pyrrolizidine alkaloid present in the plant Heliotropium indicum had shown promising cytotoxic activity in various tumor models. The compound exhibited severe toxicity to hepatocytes and bone marrow cells. The present work was aimed to evaluate the molecular mechanism of the toxicity of indicine N-oxide. We found that indicine N-oxide inhibited the proliferation of various cancer cell lines in a concentration dependent manner with IC₅₀ ranging from 46 to 100 μM. At the half maximal inhibitory concentration it blocked the cell cycle progression at mitosis without significantly altering the organization of the spindle and interphase microtubules. The toxicities of the compound at higher concentrations are attributed to its severe depolymerizing effect on both the interphase and spindle microtubules. Binding studies using purified goat brain tubulin indicated that indicine N-oxide binds to tubulin at a distinct site not shared by colchicine or taxol. It decreased the polymer mass of both purified tubulin and MAP-rich tubulin. It was found to induce cleavage of DNA using pUC18 plasmid. The interactions of indicine N-oxide on DNA were also confirmed by computational analysis; which predicted its binding site at the minor groove of DNA. These studies bring to light that the toxicities of indicine N-oxide were due to its DNA damaging effects and depolymerization of microtubules.     

三氧化二砷诱导的视网膜母细胞瘤SO-Rb50细胞白噬的研究

背景细胞的自噬是肿瘤细胞非凋亡形式的死亡过程,研究证实三氧化二砷（As2O3）可诱导肿瘤细胞凋亡,但As2O3是否可致SO—Rb50细胞发生自噬的研究鲜有报道。目的探讨As2O3体外诱导SO—Rb50细胞自噬的作用。方法用浓度为0．5、1．0、2．0、4．0μmol／L的As2O3培养液及不含As2O3的未处理组处理SO—Rb50细胞系48h,采用MTT法测定各As2O3,浓度组SO—Rb50细胞的吸光度（As2O3）值。构建自噬标志物磷酸化绿色荧光蛋白（pGFP）-LC3体外转染SO—Rb50细胞,并分为新鲜RPMI一1640培养组（未处理组）、As2O3,RPMI一1640培养组（As2O3处理组）和rapamycin培养组（阳性对照组）,于48h后行激光共焦显微镜检测细胞自噬;用自噬特异性染料单丹磺酰戊二胺（MDC）行荧光染色检测SO—Rb50细胞的自噬,并用透射电子显微镜检测SO—Rb50细胞的自噬表现,采用流式细胞仪定量检测不同浓度As2O3,处理组自噬泡阳性细胞百分比。结果未处理组和0．5、1．0、2．0、4．0txmolAs2O3,作用48h后SO—Rb50细胞的A570值分别为2．194＋0．066、1．841±0．213、1．035±0．046、0．374±0．042和0．167±0．019,总体比较差异有统计学意义（F=547．636,P〈0．05）,其中各浓度As2O3组A。值均明显低于未处理组,差异均有统计学意义（均P=0．000）。As2O3处理组和阳性对照组可见GFP—LC3融合蛋白呈点状聚集在相应的自噬泡,未处理组GFP—LC3呈弥散分布。透射电子显微镜检查可见未处理组SO—Rb50细胞超微结构正常,As2O3处理组和阳性对照组见大量双层膜状结构及自噬溶酶体。未处理组48h见极少量MDC阳性荧光颗粒,As2O3处理组及阳性对照组48h可见明显的MDC阳性荧光颗粒,聚集在细胞质相应的自噬发生区。流式细胞术检测发现未处理组和0．5、1．0、2．0、4．0μmol／LAs2O3及rapamycin作用48h后自噬泡阳性的SO—Rb50细胞百分比分别为0、15．6％、42．7％、57．9％、79．5％和89．0％,随As2O3,浓度的增加MDC阳性细胞百分比递增。结论As2O3,抑制SO—Rb50细胞的生长和增生,并致SO—Rb50细胞发生自噬;SO—Rb50细胞经As2O3处理后,自噬的发生早于细胞核的改变,早中期自噬程度呈明显的As2O3浓度依赖性。