DR4 specific TRAIL variants are more efficacious than wild-type TRAIL in pancreatic cancer

Current treatment modalities for pancreatic carcinoma afford only modest survival benefits. TRAIL, as a potent and specific inducer of apoptosis in cancer cells, would be a promising new treatment option. However, since not all pancreatic cancer cells respond to TRAIL, further improvements and optimizations are still needed. One strategy to improve the effectiveness of TRAIL-based therapies is to specifically target one of the 2 cell death inducing TRAIL-receptors, TRAIL-R1 or TRAIL-R2 to overcome resistance. To this end, we designed constructs expressing soluble TRAIL (sTRAIL) variants that were rendered specific for either TRAIL-R1 or TRAIL-R2 by amino acid changes in the TRAIL ectodomain. When we expressed these constructs, including wild-type sTRAIL (sTRAIL^wt), TRAIL-R1 (sTRAIL^DR4) and TRAIL-R2 (sTRAIL^DR5) specific variants, in 293 producer cells we found all to be readily expressed and secreted into the supernatant. These supernatants were subsequently transferred onto target cancer cells and apoptosis measured. We found that the TRAIL-R1 specific variant had higher apoptosis-inducing activity in human pancreatic carcinoma Colo357 cells as well as PancTu1 cells that were additionally sensitized by targeting of XIAP. Finally, we tested TRAIL-R1 specific recombinant TRAIL protein (rTRAIL^DR4) on Colo357 xenografts in nude mice and found them to be more efficacious than rTRAIL^wt. Our results demonstrate the benefits of synthetic biological approaches and show that TRAIL-R1 specific variants can potentially enhance the therapeutic efficacy of TRAIL-based therapies in pancreatic cancer, suggesting that they can possibly become part of individualized and tumor specific combination treatments in the future.     

TRAIL、Caspase-8和NF-κB蛋白在人骨肉瘤中的表达及其与细胞凋亡的相关性研究

目的探讨TRAIL、Caspase-8和NF—κB在人骨肉瘤组织及骨软骨瘤组织中的表达规律及其与骨肉瘤细胞凋亡的相互关系。方法应用免疫组化方法,检测TRAIL、Caspase-8和NF—κB蛋白在43例骨肉瘤及15例骨软骨瘤中的表达,并经图像分析系统测量TRAIL、Caspase-8和NF—κB蛋白的平均光密度（0D）值;用TUNEL方法检测骨肉瘤及骨软骨瘤中细胞凋亡。结果TRAIL、Caspase-8蛋白在骨肉瘤中的阳性表达均低于骨软骨瘤组织（P〈0．05）;而NF—κB蛋白在骨肉瘤中的表达高于骨软骨瘤（P〈0．05）。TRATL与Caspase-8蛋白在骨肉瘤中表达呈正相关（P〈0．01）;而TRATL与NF-κB蛋白在骨肉瘤中表达呈负相关（P〈0．01）。骨肉瘤组细胞凋亡指数（AI）显著低于骨软骨瘤组（P〈0．05）;TRAIL、Caspase-8蛋白表达与细胞凋亡均呈正相关（P〈0．01）;而NF—κB蛋白表达与骨肉瘤细胞凋亡呈负相关（P〈0．01）。结论TRAIL基因可能是诱导骨肉瘤细胞凋亡的分子基础,参与了其发生发展过程中细胞凋亡的调控。Caspase-8作为影响细胞凋亡过程的因子,在骨肉瘤发生、发展中发挥作用。NF-κB在骨肉瘤细胞增殖与凋亡中具有重要作用。TRAIL、Caspase-8蛋白呈低表达,可能受NF—κB高表达的调控而不能诱导细胞凋亡。提示三者在骨肉瘤的发生、发展中起协同作用。     

融合蛋白Kininogen D5_（60-148）-TRAIL_（114-281）的表达及其抑制血管新生和诱导细胞凋亡的作用

目的：采用原核表达系统表达人Kininogen D560148TRAIL114281融合蛋白,并对其生物学活性进行研究。方法：PCR技术扩增Kininogen D560148和TRAIL114281的编码序列,分别构建原核表达载体pMALKininogen D560148（pMALKD5）、pMALTRAIL114281（pMALTRAIL）和pMALKininogen D560148 TRAIL114281（pMALKT）,重组质粒分别转化大肠杆菌BL21,IPTG诱导表达融合蛋白MBPKD5、MBPTRAIL和MBPKT,并经亲和层析纯化。MTT法检测细胞的增殖,管状形成实验检测内皮细胞血管形成,流式细胞仪和电镜检测细胞凋亡。结果：成功构建原核表达载体pMALKD5、pMALTRAIL和pMALKT,并获得纯化的融合蛋白MBPKD5、MBPTRAIL和MBPKT。融合蛋白MBPKT与MBPKD5、MBPTRAIL相比可显著抑制内皮细胞ECV304和胰腺癌细胞SW1990的增殖、明显抑制ECV304细胞体外管腔的形成,同时,MBPKT剂量依赖性地诱导SW1990细胞凋亡。结论：融合蛋白Kininogen D560148 TRAIL114281既能诱导肿瘤细胞凋亡又能抑制血管生成,为进一步开发靶向性抗肿瘤药物奠定了基础     

TRAIL及其受体DR5、DcR1在宫颈癌中的表达

目的：探讨TRAIL及其受体DR5、DcR1在宫颈癌中的表达及其临床意义。方法：应用免疫组化SP法对10例正常宫颈组织、18例宫颈上皮内瘤变（CIN）组织和40例宫颈癌组织中TRAIL、DR5及DcR1的表达情况进行检测,并结合患者年龄、肿瘤分化程度、组织类型、有无淋巴结转移等临床病理因素进行分析。结果：TRAIL及DcR1在正常宫颈组织中的表达高于宫颈癌组织;宫颈癌组织中,TRAIL阳性表达随组织学分级降低而降低;DR5在正常宫颈、CIN和宫颈癌组织中的表达呈递增趋势。结论：TRAIL、DR5及DcR1的异常表达在宫颈癌变过程中起一定的作用。     

人胎盘TRAIL基因的克隆和在大肠杆菌中的表达

从人胎盘中提取总RNA,利用RT-PCR技术扩增了可溶性TRAIL(凋亡素配体2)基因片段.序列分析表明该基因序列与国外发表的可溶性TRAIL基因片段的序列完全相同.将该基因片段插入到含T7启动子的质粒pET-28c(+)上,构建表达质粒pET-28c(+)TRAIL,转化大肠杆菌BL21(DE3),筛选获得表达菌株BL-pET-28c(+)TRAIL.表达菌经1 mmol/L的IPTG诱导表达4h后,产生大量的重组人TRAIL蛋白,SDS-PAGE扫描计算机灰度分析表明,表达的重组蛋白占菌株可溶性蛋白的40%以上.     

Cryptolepine,isolated from Sida acuta,sensitizes human gastric adenocarcinoma cells to TRAIL‐induced apoptosis

Bioassay guided separation of Sida acuta whole plants led to the isolation of an alkaloid, cryptolepine (1), along with two kaempferol glycosides (2–3). Compound 1 showed strong activity in overcoming TRAIL‐resistance in human gastric adenocarcinoma (AGS) cells at 1.25, 2.5 and 5 μm . Combined treatment of 1 and TRAIL sensitized AGS cells to TRAIL‐induced apoptosis at the aforementioned concentrations. Copyright © 2010 John Wiley & Sons, Ltd.     

PBOX-15, a novel microtubule targeting agent, induces apoptosis, upregulates death receptors, and potentiates TRAIL-mediated apoptosis in multiple myeloma cells

Background:

In recent years, much progress has been made in the treatment of multiple myeloma. However, a major limitation of existing chemotherapeutic drugs is the eventual emergence of resistance; hence, the development of novel agents with new mechanisms of action is pertinent. Here, we describe the activity and mechanism of action of pyrrolo-1,5-benzoxazepine-15 (PBOX-15), a novel microtubule-targeting agent, in multiple myeloma cells.

Methods:

The anti-myeloma activity of PBOX-15 was assessed using NCI-H929, KMS11, RPMI8226, and U266 cell lines, and primary myeloma cells. Cell cycle distribution, apoptosis, cytochrome c release, and mitochondrial inner membrane depolarisation were analysed by flow cytometry; gene expression analysis was carried out using TaqMan Low Density Arrays; and expression of caspase-8 and Bcl-2 family of proteins was assessed by western blot analysis.

Results:

Pyrrolo-1,5-benzoxazepine-15 induced apoptosis in ex vivo myeloma cells and in myeloma cell lines. Death receptor genes were upregulated in both NCI-H929 and U266 cell lines, which displayed the highest and lowest apoptotic responses, respectively, following treatment with PBOX-15. The largest increase was detected for the death receptor 5 (DR5) gene, and cotreatment of both cell lines with tumour necrosis factor-related apoptosis-inducing ligand (TRAIL), the DR5 ligand, potentiated the apoptotic response. In NCI-H929 cells, PBOX-15-induced apoptosis was shown to be caspase-8 dependent, with independent activation of extrinsic and intrinsic apoptotic pathways. A caspase-8-dependent decrease in expression of Bim_EL preceded downregulation of other Bcl-2 proteins (Bid, Bcl-2, Mcl-1) in PBOX-15-treated NCI-H929 cells.

Conclusion:

PBOX-15 induces apoptosis and potentiates TRAIL-induced cell death in multiple myeloma cells. Thus, PBOX-15 represents a promising agent, with a distinct mechanism of action, for the treatment of this malignancy.     

Drug-induced caspase 8 upregulation sensitises cisplatin-resistant ovarian carcinoma cells to rhTRAIL-induced apoptosis

Background:

Drug resistance is a major problem in ovarian cancer. Triggering apoptosis using death ligands such as tumour necrosis factor-related apoptosis inducing ligand (TRAIL) might overcome chemoresistance.

Methods:

We investigated whether acquired cisplatin resistance affects sensitivity to recombinant human (rh) TRAIL alone or in combination with cisplatin in an ovarian cancer cell line model consisting of A2780 and its cisplatin-resistant subline CP70.

Results:

Combining cisplatin and rhTRAIL strongly enhanced apoptosis in both cell lines. CP70 expressed less caspase 8 protein, whereas mRNA levels were similar compared with A2780. Pre-exposure of particularly CP70 to cisplatin resulted in strongly elevated caspase 8 protein and mRNA levels. Caspase 8 mRNA turnover and protein stability in the presence or absence of cisplatin did not differ between both cell lines. Cisplatin-induced caspase 8 protein levels were essential for the rhTRAIL-sensitising effect as demonstrated using caspase 8 small-interfering RNA (siRNA) and caspase-8 overexpressing constructs. Cellular FLICE-inhibitory protein (c-FLIP) and p53 siRNA experiments showed that neither an altered caspase 8/c-FLIP ratio nor a p53-dependent increase in DR5 membrane expression following cisplatin were involved in rhTRAIL sensitisation.

Conclusion:

Cisplatin enhances rhTRAIL-induced apoptosis in cisplatin-resistant ovarian cancer cells, and induction of caspase 8 protein expression is the key factor of rhTRAIL sensitisation.     

Diosgenin induces death receptor-5 through activation of p38 pathway and promotes TRAIL-induced apoptosis in colon cancer cells

Previously, we demonstrated that diosgenin induced apoptosis in colorectal cancer cell lines HCT-116 and HT-29. HT-29 cells have been reported to be one of the most resistant colorectal cancer cell lines to TRAIL-induced apoptosis. In this study, we investigated the effect of diosgenin on TRAIL-induced apoptosis in HT-29 cells. We showed that diosgenin sensitizes HT-29 cells to TRAIL-induced apoptosis. Mechanisms underlying this sensitization mainly involved diosgenin-induced p38 MAPK pathway activation and subsequent DR5 overexpression. Furthermore, we showed that diosgenin alone, TRAIL alone or combination treatment increased COX-2 expression and that the use of a COX-2 inhibitor further increased apoptosis induction.