TRAIL联合顺铂诱导胶质瘤细胞凋亡的机制

作为新型的抗肿瘤药物,肿瘤坏死因子相关凋亡诱导配体(TRAIL)已进入临床Ⅱ期试验阶段[1].研究发现,TRAIL可以诱导包括胶质瘤在内的多种肿瘤细胞发生凋亡,但大多恶性胶质瘤细胞对TRAIL耐药[2].前期研究的实验发现,原代培养的胶质瘤细胞对TRAIL诱导凋亡的敏感性不同,检测发现死亡受体(DR)5的表达量不同,并当TRAIL与化疗药物联合作用后可发挥协同作用[3～5].因此,本文进一步对TRAIL与化疗药物联合作用诱导胶质瘤细胞凋亡的机制进行研究,为TRAIL作为肿瘤治疗新药提供新的实验依据.     

TRAIL及其受体与HBV相关慢性肝病相关性的研究进展

肿瘤坏死因子相关凋亡诱导配体(TNF-related apoptosis inducing ligand,TRAIL)归属于肿瘤坏死因子超家族,与死亡受体结合后,激活caspase瀑布样级联反应,可诱导肿瘤细胞、转化细胞及病毒感染细胞发生凋亡,而对正常组织及细胞无凋亡诱导作用。TRAIL及其受体通过与HBV、细胞因子等的相互作用,在HBV相关慢性肝病的发病机制中发挥着重要作用。此外,体内TRAIL表达还与慢性乙型病毒性肝炎患者抗病毒治疗存在一定的关联性。本文对TRAIL及其受体与HBV相关慢性肝病的相关性进行综述,为进一步明确两者间的关系提供理论依据。     

结肠癌获得性肿瘤坏死因子相关凋亡诱导配体基因耐药机制

肿瘤坏死因子相关凋亡诱导配体（TRAIL）能杀灭众多肿瘤细胞而不损伤多数正常细胞,它的发现为肿瘤基因治疗带来了新的曙光,但深入研究发现,TRAIL基因治疗的进一步发展受到了耐药问题的困扰.了解TRAIL基因耐药机制,尤其是治疗过程中形成的获得性耐药机制,对于预防并逆转耐药具有重要意义.     

肿瘤坏死因子相关凋亡诱导配体与肝细胞凋亡的相关性

肿瘤坏死因子相关的调亡诱导配体是TNF家族成员之一,通过其死亡受体诱导凋亡.研究显示TRAIL/死亡受体途径参与多种肝脏病理过程,本文就TRAIL/死亡受体途径的特性、致凋亡的机制及与肝细胞凋亡关系的最新进展作一综述.     

端粒酶逆转录酶RNA干扰增加肿瘤坏死因子相关凋亡诱导配体活性

肿瘤坏死因子相关凋亡诱导配体（TNFα-related apoptosis-inducing ligand,TRAIL）为肿瘤坏死因子家族成员,与TNFα和Fas配体不同的是它仅诱导病毒感染细胞、转化细胞和肿瘤细胞凋亡,不引起炎症反应而杀伤正常细胞.TRAIL诱导大多数肿瘤细胞凋亡,但也有部分肿瘤细胞不敏感,且TRAIL对不敏感的肿瘤细胞有促增殖作用。     

原代培养的恶性胶质瘤细胞表达死亡受体与TRAIL抵抗的关系

肿瘤坏死因子相关凋亡诱导配体( TRAIL)是肿瘤坏死因子超家族中的一员,作为肿瘤治疗的新药,在美国已进入临床Ⅱ期试验阶段[1].但由于在肿瘤治疗研究中,TRAIL一直存在治疗抵抗,因此,本文对原代培养的恶性胶质瘤细胞进行研究,通过观察TRAIL的两种受体——死亡受体(DR)4、DR5在恶性胶质瘤细胞中的表达,探讨在原代培养肿瘤细胞中存在的TRAIL抵抗问题.     

γ-干扰素加强肿瘤坏死因子相关凋亡诱导配体抑制大肠癌细胞及其机制

有研究发现，部分肿瘤细胞对肿瘤坏死因子相关凋亡诱导配体(TRAIL)诱导的凋亡作用并不敏感，这限制了TRAIL在抗肿瘤治疗中的应用。有研究证实，γ-干扰素(IFN-γ)能增强TRAIL对肿瘤细胞的凋亡作用。我们以体外培养人大肠癌细胞株RKO为研究对象，探讨IFN-γ加强TRAIL的凋亡诱导作用，以及IFN-γ对TRAIL及其受体表达的调节作用。     

肿瘤坏死因子相关性凋亡诱导配体与缺血性卒中

肿瘤坏死因子相关性凋亡诱导配体(TRAIL)是肿瘤坏死因子超家族成员,可选择性诱导肿瘤细胞凋亡。近年来的研究表明,缺血后脑组织中可见TRAIL表达,并在神经元凋亡中起重要作用。     

肿瘤坏死因子相关凋亡诱导配体(TRAIL)受体的表达及TRAIL的抗癌作用

肿瘤坏死因子相关凋亡诱导配体(TRAIL)可特异性杀伤肿瘤细胞同时赦免正常细胞。最近有报道，化疗可加强TRAIL诱导肺癌细胞凋亡。本研究意在观察TRAIL受体(TRAILR)的表达及TRAIL与顺铂、紫杉醇联合作用的抑癌性。     

XAF1增加TRAIL诱导的肝癌细胞凋亡的敏感性

背景:肿瘤坏死因子(TNF)相关凋亡诱导配体(TRAIL)可特异性诱导肿瘤细胞凋亡,但部分肿瘤细胞对TRAIL不敏感甚至耐药。目的:探讨X连锁凋亡抑制蛋白(XIAP)相关因子1(XAF1)是否可增加TRAIL诱导的肝癌细胞株凋亡的敏感性。方法:重组人TRAIL(rhTRAIL)因子分别加入3株肝癌细胞株SMMC7721、HepG2和Bel-7404中培养,联合或不联合相同感染复数(MOI)的重组腺病毒Ad5/F35-XAF1和对照空病毒Ad5/F35-Null。作用48h后,以MTT法检测细胞活力,以Annexin V-FITC/PI法检测细胞凋亡率。结果:随着TRAIL浓度的增加,3株肝癌细胞株的细胞活力均不同程度降低。TRAIL与Ad5/F35-XAF1联合作用后,其细胞活力显著低于单独TRAIL组,而Ad5/F35-Null组细胞活力与单独TRAIL组无明显差异。与空白对照组和Ad5/F35-Null组相比,TRAIL组和Ad5/F35-XAF1组3株肝癌细胞株的凋亡率均显著增加。TRAIL与Ad5/F35-XAF1联合作用后,细胞凋亡率显著高于Ad5/F35-XAF1组或TRAIL组。结论:XAF1可明显增加TRAIL诱导的肝癌细胞凋亡的敏感性,两者联合应用对诱导不同肝癌细胞凋亡具有协同作用。     

Designed tumor necrosis factor-related apoptosis-inducing ligand variants initiating apoptosis exclusively via the DR5 receptor

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a potential anticancer drug that selectively induces apoptosis in a variety of cancer cells by interacting with death receptors DR4 and DR5. TRAIL can also bind to decoy receptors (DcR1, DcR2, and osteoprotegerin receptor) that cannot induce apoptosis. The occurrence of DR5-responsive tumor cells indicates that a DR5 receptor-specific TRAIL variant will permit tumor-selective therapies. By using the automatic design algorithm FOLD-X, we successfully generated DR5-selective TRAIL variants. These variants do not induce apoptosis in DR4-responsive cell lines but show a large increase in biological activity in DR5-responsive cancer cell lines. Even wild-type TRAIL-insensitive ovarian cancer cell lines could be brought into apoptosis. In addition, our results demonstrate that there is no requirement for antibody-mediated cross-linking or membrane-bound TRAIL to induce apoptosis through DR5.     

Proteasome inhibition sensitizes hepatocellular carcinoma cells, but not human hepatocytes, to TRAIL

TRAIL exhibits potent anti-tumor activity on systemic administration in mice. Because of its proven in vivo efficacy, TRAIL may serve as a novel anti-neoplastic drug. However, approximately half of the tumor cell lines tested so far are TRAIL resistant, and potential toxic side effects of certain recombinant forms of TRAIL on human hepatocytes have been described. Pretreatment with the proteasome inhibitor MG132 and PS-341 rendered TRAIL-resistant hepatocellular carcinoma (HCC) cell lines but not primary human hepatocytes sensitive for TRAIL-induced apoptosis. We investigated the different levels of possible MG132-induced interference with resistance to apoptotic signal transduction. Although proteasome inhibition efficiently suppressed nuclear factor-kappaB (NF-kappaB) activity, specific suppression of NF-kappaB by mutIkappaBalpha failed to sensitize TRAIL-resistant cell lines for TRAIL-induced apoptosis. In contrast to the previously reported mechanism of sensitization by 5-fluorouracil (5-FU), cellular FLICE-inhibitory protein (cFLIP)(L) and cFLIP(S) were markedly upregulated in the TRAIL death inducing signaling complex (DISC) by proteasome inhibitor pretreatment. Compared with 5-FU pretreatment, caspase-8 was more efficiently recruited to the DISC in MG132 pretreated cells despite the presence of fewer death receptors and more cFLIP in the DISC. But downregulation of cFLIP by short interference RNA (siRNA) further sensitized the HCC cell lines. In conclusion, these results show that otherwise chemotherapy-resistant tumor cells can be sensitized for TRAIL-induced apoptosis at the DISC level in the presence of high levels of cFLIP, which suggests the existence of an additional factor that modulates the interaction of FADD and the TRAIL death receptors. Of clinical relevance, proteasome inhibitors sensitize HCC cells but not primary human hepatocytes for TRAIL-induced apoptosis.     

Combined treatment with TRAIL and PPARγ ligands overcomes chemoresistance of ovarian cancer cell lines

Purpose  

Ovarian cancer accounts for the highest mortality among all gynecological cancers, mainly due to the fast developing chemoresistance. The death ligand TRAIL induces apoptosis and is able to sensitize tumor cells to cytostatic drugs without affecting physiological tissue. Combined treatment of TRAIL and the antidiabetic acting PPARγ ligands was shown to induce apoptosis synergistically in different ovarian cancer cell lines.     

Sensitivity of adult T-cell leukaemia lymphoma cells to tumour necrosis factor-related apoptosis-inducing ligand

Tumour necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) induces apoptosis in many transformed cells, but not in normal cells, and hence TRAIL has recently emerged as a novel anti-cancer agent. Adult T-cell leukaemia lymphoma (ATLL) is a neoplasm of T-lymphocyte origin aetiologically associated with human T-lymphotropic virus type 1 (HTLV-I), and is resistant to standard anti-cancer therapy. We thus characterized the sensitivity of ATLL cells to TRAIL in this study. Although most primary ATLL cells and cell lines expressed TRAIL death receptors on their surface, they showed only restricted sensitivity to TRAIL. Among the 10 ATLL cell lines examined, one was sensitive, but two had insufficient death-receptor expression, two had an unknown resistant mechanism with abrogation of the death signal upstream of caspase-8, and the remaining five showed attenuation of the signal in both extrinsic and intrinsic pathways by X-linked inhibitor of apoptosis and Bcl-2/Bcl-xL respectively. Furthermore, the level of HTLV-I tax expression was significantly correlated to TRAIL resistance. Interestingly, ATLL cells themselves expressed TRAIL on the cell surface. Constitutive production of TRAIL may offer resistance, thus allowing the development of TRAIL-resistant ATLL cells. Consequently, the resistant mechanism in ATLL cells against TRAIL was assigned to multiple factors and was not explained by a definitive single agent.     

P60-c-src suppresses apoptosis through inhibition of caspase 8 activation in hepatoma cells, but not in primary hepatocytes

BACKGROUND/AIMS: Failure to induce apoptosis triggered by members of the death receptor family has been described in hepatocellular carcinoma (HCC) and sensitization of malignant cells to pro-apoptotic molecules such as TRAIL has been proposed as an alternative cancer therapy. Limiting to this approach are the resistance of many tumor cells to TRAIL and safety concerns about the toxicity of TRAIL in normal hepatocytes. METHODS: We here explored the possibility that the protooncogene c-Src, known to be overexpressed in a variety of tumors, could be specifically responsible for the loss of response to receptor-mediated apoptosis. RESULTS: Cotreatment of several hepatoma cell lines with the Src inhibitor PP2 potently sensitized these cells to TRAIL and CD95, dramatically decreasing effective doses of TRAIL to as low as 1 ng/ml. Remarkably, Src-inhibition did not synergize with TRAIL signaling in primary hepatocytes. Specific siRNAs showed that the effect was due to blockade of p60(c-Src) and occurred through increased recruitment of caspase 8. CONCLUSIONS: We provide evidence that p60(c-Src) is an important and effective suppressor of receptor-mediated apoptosis in hepatoma cells but not in primary human hepatocytes. Inhibition of Src sensitizes tumor cells to apoptosis and decreases effective doses of TRAIL to therapeutic concentrations.     

Expression and antitumor effects of TRAIL in human cholangiocarcinoma

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL)/Apo2L has been recently identified as important in promoting programmed cell death in breast and colon adenocarcinomas. In this study, we investigated the expression and therapeutic potential of TRAIL in cholangiocarcinoma, one of the most devastating human hepatic malignancies. Expression of TRAIL receptors was determined in 13 patients with resectable intrahepatic cholangiocarcinoma. Cellular effects of TRAIL in promoting apoptosis of human cholangiocarcinoma cells were analyzed after exposure to recombinant protein, as well as following transfection with a cDNA expression construct. In vivo effects of TRAIL on tumor growth were investigated after subcutaneous injection of cholangiocarcinoma cells into nude mice. Analysis of 13 clinical and tissue samples revealed that TRAIL receptors containing the death domain were present in all cholangiocarcinomas as well as paired normal hepatic tissues derived from surgically resected margins. In contrast, 7 tumors did not express the TRAIL decoy receptors lacking the death domain; such receptors were detectable in all of the normal hepatic tissue counterparts. Recombinant TRAIL induced extensive programmed cell death in cholangiocarcinoma cell lines lacking decoy receptor expression. Transfection of the ectodomain of TRAIL also induced cellular apoptosis; this effect was abolished by introduction of the generalized lymphoproliferative disease-like mutation in the TRAIL protein. Finally, in vivo administration of recombinant TRAIL substantially inhibited subcutaneous tumor growth of human cholangiocarcinoma cells. Induction of apoptosis in tumor cells is possible with a biologically active TRAIL, and suggests that this cytokine is a promising antitumor agent against human cholangiocarcinoma.     

Transforming growth factor beta can mediate apoptosis via the expression of TRAIL in human hepatoma cells

Transforming growth factor beta (TGF-beta) has been shown to induce apoptotic cell death in normal and transformed hepatocytes. However, the exact mechanism through which TGF-beta induces cell death is still unknown. We examined a potential role of various death receptor/ligand systems in TGF-beta-induced apoptosis and identified the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) as a mediator of TGF-beta-induced apoptosis in hepatoma cells. TGF-beta-induced apoptosis is significantly impaired upon blockage of TRAIL. We show that TRAIL is upregulated in hepatoma cells upon treatment with TGF-beta, whereas TRAIL receptor levels remain unchanged. In conclusion, our results provide evidence that the TRAIL system is critically involved in TGF-beta-induced cell death in liver pathology.     

Effect of NF-κB, survivin, Bcl-2 and Caspase3 on apoptosis of gastric cancer cells induced by tumor necrosis factor related apoptosis inducing ligand

AIM: To study the effect of NF-κB, survivin, Bd-2 and Caspase3 on tumor necrosis factors related apoptosis inducing ligand (TRAIL) induced apoptosis of gastric cancer cells. METHODS: Gastric cancer cells of SGC-7901, MKN28, MKN45 and AGS lines were cultured in PRMI-1640 medium and the apoptosis rates of the cells of 4 lines were observed after treatment of tumor necrosis factors related apoptosis indudng ligand (TRAIL) with a flow cytometer. The expression of NF-κB, survivin, Bcl-2 and Caspase3 in gastric cancer cells of 4 lines was analyzed with Western blot. RESULTS: After the gastric cancer cells were exposed to TRAIL 300 ng/ml for 24 hours, the apoptosis rate was 36.05%, 20.27%, 16.50% and 11.80% in MKN28, MKN45,AGS and SC-C-7901cells respectively. Western blot revealed that the expressions of NF-EB and survivin were lower in MKN28 cells than in MKN45, AGS and SGC-7901 cells. In contrast, the expression of Caspase3 was higher in MKN28 cells than in MKN45, AGS and SGC-7901 cells. CONCLUSION: There is a selectivity of TRAIL potency to induce apoptosis in gastric cancer cells of different cell lines.The anticancer potency of TRAIL is associated with the decreased expression of NF-κB and survivin and increased expression of Caspase3 of gastric cancer cells.