磁场抗肿瘤生物效应机制

磁场抑制肿瘤机制较为复杂,并且有众多的影响因素制约着磁场作用效果。磁场可以抑制肿瘤细胞分裂,并可作用于肿瘤细胞的细胞器、细胞膜,以及非肿瘤组织,从而间接起到抑制肿瘤的作用。其可能机制为磁场能选择性破坏肿瘤细胞的DNA,抑制肿瘤细胞的恶性增殖;激活自由基间接损伤DNA;调控肿瘤细胞的增殖分裂周期;作用于肿瘤细胞质内线粒体、蛋白酶等生命物质以及肿瘤细胞的细胞膜,从而破坏肿瘤细胞功能,减少肿瘤细胞的养分而抑制或杀死肿瘤细胞等。     

磁场抗肿瘤生物效应机制

磁场抑制肿瘤机制较为复杂,并且有众多的影响因素制约着磁场作用效果.磁场可以抑制肿瘤细胞分裂,并可作用于肿瘤细胞的细胞器、细胞膜,以及非肿瘤组织,从而间接起到抑制肿瘤的作用.其可能机制为磁场能选择性破坏肿瘤细胞的DNA,抑制肿瘤细胞的恶性增殖;激活自由基间接损伤DNA;调控肿瘤细胞的增殖分裂周期;作用于肿瘤细胞质内线粒体、蛋白酶等生命物质以及肿瘤细胞的细胞膜,从而破坏肿瘤细胞功能,减少肿瘤细胞的养分而抑制或杀死肿瘤细胞等.     

间充质干细胞对肿瘤细胞的分子作用机制

间充质干细胞(MSC)不但对肿瘤细胞具有良好的靶向性,而且可以直接抑制肿瘤生长或作为新兴的基因治疗载体在肿瘤局部持续高效地表达外源基因,抑制肿瘤的生长和转移.同时,MSC也可通过促进肿瘤间质重构和肿瘤血管形成、抑制肿瘤局部机体免疫以及改变肿瘤表型而促进肿瘤生长.相反的作用机制可能与MSC的来源、异质性、肿瘤细胞微环境或...     

钙库调控性钙通道在肿瘤细胞中的矛盾作用及其机制

在非兴奋型细胞中,钙库调控性钙通道（SOCC）是胞外钙离子进入胞内的最主要途径,可调控多种肿瘤细胞的生物学特性,包括黏附、分泌、运动、基因表达、增殖、分裂与凋亡等。基质交联分子1（STIMl）和Orail是SOCC的重要组成部分,故过表达或抑制表达STIMI／Orail可调控SOCC活性和肿瘤细胞的生物学特性。而SOCC对肿瘤细胞的作用却自相矛盾,既可促进肿瘤进展,又可抑制肿瘤进展。SOCC有望成为治疗肿瘤的一个新靶点,但其机制复杂,既需考虑肿瘤细胞类型,还需考虑外界刺激因子对肿瘤细胞的作用。     

ZD1839治疗头颈部肿瘤研究进展

头颈部肿瘤多过度表达表皮生长因子受体(EGFR)。EGFR酪氨酸激酶抑制剂ZD1839可阻断EGFR介导的信号转导途径,进而抑制肿瘤细胞增殖,将肿瘤细胞阻滞在G_1期,促进肿瘤细胞凋亡并抑制血管生成,与放化疗联合应用具有协同抗肿瘤作用,可用于头颈部肿瘤的治疗。现综述ZD1839治疗头颈部肿瘤的研究进展。     

ZD1839治疗头颈部肿瘤研究进展

头颈部肿瘤多过度表达表皮生长因子受体（EGFR）。EGFR酪氨酸激酶抑制剂ZD1839可阻断EGFR介导的信号转导途径,进而抑制肿瘤细胞增殖,将肿瘤细胞阻滞在G1期,促进肿瘤细胞凋亡并抑制血管生成,与放化疗联合应用具有协同抗肿瘤作用,可用于头颈部肿瘤的治疗。现综述ZD1839治疗头颈部肿瘤的研究进展。     

非甾体类消炎药治疗肿瘤机制

传统观点认为非甾体类消炎药(NSAID)是通过抑制环氧合酶-2(COX-2)的活性,产生一系列抑制肿瘤生长的生物学效应.近几年研究发现NSAID还可通过其他途径抑制肿瘤生长,如直接诱导肿瘤细胞凋亡、改变肿瘤细胞周期等.现就NSAID的抑癌机制作一概述.     

生存素在肿瘤中的作用及其耐药机制

肿瘤治疗中的耐药问题是影响疾病转归的重要因素,目前已有大量研究发现,生存素（survivin）具有抑制肿瘤细胞凋亡、调控肿瘤细胞周期、促进血管生成、促进肿瘤转移的作用,并可与多种基因及蛋白相互作用,影响肿瘤细胞耐药性.     

非甾体类消炎药治疗肿瘤机制

传统观点认为非甾体类消炎药(NSAID)是通过抑制环氧合酶．2(COX-2)的活性，产生一系列抑制肿瘤生长的生物学效应。近几年研究发现NSAID还可通过其他途径抑制肿瘤生长，如直接诱导肿瘤细胞凋亡、改变肿瘤细胞周期等。现就NSAID的抑癌机制作一概述；     

肿瘤间质与恶性肿瘤的治疗进展

目前,临床抗肿瘤的治疗更多着眼于对肿瘤细胞的抑制和杀伤,而对肿瘤间质干预的关注不多.现已证实,肿瘤间质与肿瘤细胞间具有密切的相互作用,不仅参与肿瘤的发生、发展、侵袭及转移过程,还可影响肿瘤细胞对放射治疗及抗肿瘤药物的敏感性,影响抗肿瘤治疗的疗效.肿瘤间质可直接或间接影响肿瘤的发生发展过程,机制复杂.有效干预肿瘤间质可提高抗肿瘤治疗效果.本文就肿瘤间质成分及以肿瘤间质为靶点的抗肿瘤治疗的相关研究进展进行综述.     

Induction of p21-Dependent Senescence by an NAE Inhibitor, MLN4924, as a Mechanism of Growth Suppression

Cullin-RING ubiquitin ligase (CRL), with its founding member of SKP1-Cullins-F-box proteins (SCF) E3 ubiquitin ligase, is the largest family of E3 ligases, which requires cullin neddylation for its activation. Recently, an inhibitor of NEDD8 activating enzyme (NAE), MLN4924, was reported to block cullin neddylation and inactivate CRL/SCF E3, resulting in apoptosis induction and tumor suppression both in vitro and in vivo. We report here that apoptosis is not the sole mechanism by which MLN4924 suppresses tumor cell growth because apoptosis is moderately induced by the drug in some cancer cell lines and drug-induced growth suppression is only partially blocked by a pan-caspase inhibitor, z-VAD. MLN4924 treatment induces the characteristics of senescence phenotypes as evidenced by enlarged and flattened cellular morphology and positive staining of senescence-associated β-Gal. MLN4924-induced senescence is associated with cellular response to DNA damage, triggered by accumulation of DNA-licensing proteins CDT1 and ORC1, as a result of inactivation of CRL/SCF E3s. The senescence occurs in the manner independent of pRB/p16 and p53, but dependent on p21, a known substrate of CRL/SCF E3s and a mediator of senescence, which accumulates on CRL/SCF inactivation by MLN4924. Furthermore, MLN4924-induced senescence is irreversible and coupled with persistent accumulation of p21 and sustained activation of DNA damage response. Our study reveals a novel mechanism of MLN4924 action and showed that MLN4924 could be further developed as an effective anticancer agent by inducing apoptosis and irreversible senescence.     

Treatment-emergent mutations in NAEβ confer resistance to the NEDD8-activating enzyme inhibitor MLN4924

MLN4924 is an investigational small-molecule inhibitor of NEDD8-activating enzyme (NAE) in clinical trials for the treatment of cancer. MLN4924 is a mechanism-based inhibitor, with enzyme inhibition occurring through the formation of a tight-binding NEDD8-MLN4924 adduct. In cell and xenograft models of cancer, we identified treatment-emergent heterozygous mutations in the adenosine triphosphate binding pocket and NEDD8-binding cleft of NAEβ as the primary mechanism of resistance to MLN4924. Biochemical analyses of NAEβ mutants revealed slower rates of adduct formation and reduced adduct affinity for the mutant enzymes. A compound with tighter binding properties was able to potently inhibit mutant enzymes in cells. These data provide rationales for patient selection and the development of next-generation NAE inhibitors designed to overcome treatment-emergent NAEβ mutations.     

Synergistic inhibition of autophagy and neddylation pathways as a novel therapeutic approach for targeting liver cancer

Liver cancer is the second-most frequent cause of cancer death in the world and is highly treatment resistant. We reported previously that inhibition of neddylation pathway with specific NAE inhibitor MLN4924, suppressed the malignant phenotypes of liver cancer. However, during the process, MLN4924 induces pro-survival autophagy as a mechanism of drug resistance. Here, we report that blockage of autophagy with clinically-available autophagy inhibitors (e.g. chloroquine) significantly enhanced the efficacy of MLN4924 on liver cancer cells by triggering apoptosis. Mechanistically, chloroquine enhanced MLN4924-induced up-regulation of pro-apoptotic proteins (e.g. NOXA) and down-regulation of anti-apoptotic proteins. Importantly, the down-regulation of NOXA expression via siRNA silencing substantially attenuated apoptosis of liver cancer cells. Further mechanistic studies revealed that blockage of autophagy augmented MLN4924-induced DNA damage and reactive oxygen species (ROS) generation. The elimination of DNA damage or blockage of ROS production significantly reduced the expression of NOXA, and thereby attenuated apoptosis and reduced growth inhibition of liver cancer cells. Moreover, blockage of autophagy enhanced the efficacy of MLN4924 in an orthotopic model of human liver cancer, with induction of NOXA and apoptosis in tumor tissues. These findings provide important preclinical evidence for clinical investigation of synergistic inhibition of neddylation and autophagy in liver cancer.     

Radiosensitization of human pancreatic cancer cells by MLN4924, an investigational NEDD8-activating enzyme inhibitor

Radiotherapy is used in locally advanced pancreatic cancers in which it can improve survival in combination with gemcitabine. However, prognosis is still poor in this setting in which more effective therapies remain needed. MLN4924 is an investigational small molecule currently in phase I clinical trials. MLN4924 inhibits NAE (NEDD8 Activating Enzyme), a pivotal regulator of the E3 ubiquitin ligase SCF (SKP1, Cullins, and F-box protein), that has been implicated recently in DNA damage and repair. In this study, we provide evidence that MLN4924 can be used as an effective radiosensitizer in pancreatic cancer. Specifically, MLN4924 (20-100 nmol/L) effectively inhibited cullin neddylation and sensitized pancreatic cancer cells to ionizing radiation in vitro with a sensitivity enhancement ratio of approximately 1.5. Mechanistically, MLN4924 treatment stimulated an accumulation of several SCF substrates, including CDT1, WEE1, and NOXA, in parallel with an enhancement of radiation-induced DNA damage, aneuploidy, G(2)/M phase cell-cycle arrest, and apoptosis. RNAi-mediated knockdown of CDT1 and WEE1 partially abrogated MLN4924-induced aneuploidy, G(2)/M arrest, and radiosensitization, indicating a causal effect. Furthermore, MLN4924 was an effective radiosensitizer in a mouse xenograft model of human pancreatic cancer. Our findings offer proof-of-concept for use of MLN4924 as a novel class of radiosensitizer for the treatment of pancreatic cancer.     

MLN4924对紫杉醇耐药的前列腺癌细胞增殖和凋亡的影响

目的:研究MLN4924对紫杉醇耐药的前列腺癌细胞增殖和凋亡的影响,从而为紫杉醇耐药前列腺癌的临床治疗提供新的理论依据。方法:不同浓度的MLN4924作用紫杉醇耐药的前列腺癌细胞PC3-TxR和DU145-TxR 48和72小时后,采用MTS检测细胞活力。Western blot检测凋亡相关蛋白Caspase-3、CDT1、p27以及EMT标志物水平。结果:MLN4924能够显著抑制PC3-TxR和DU145-TxR细胞的增殖,并且具有时间和浓度的依懒性。Western blot结果显示MLN4924作用后显著增加细胞内凋亡相关蛋白Caspase-3、CDT1和p27的表达。结论:MLN4924能够显著抑制紫杉醇耐药的前列腺癌细胞增殖、促进细胞凋亡,其相关机制为MLN4924可通过上调p27蛋白表达促进紫杉醇耐药的前列腺癌细胞凋亡。     

Targeting protein neddylation with an NEDD8-activating enzyme inhibitor MLN4924 induced apoptosis or senescence in human lymphoma cells

Recent studies indicate that post-translational protein neddylation is required for the maintenance of cell viability in several lymphoma cell lines, while inhibition of the neddylation pathway with an NEDD8-activating enzyme (NAE) inhibitor MLN4924 induces apoptosis in lymphoma cells. However, the mechanism by which neddylation inhibition induces apoptosis in lymphoma cells has not been fully elucidated. Moreover, it is unknown whether neddylation inhibition triggers non-apoptotic cell-killing responses, such as cell senescence, in lymphoma cells. Here, we report that MLN4924 specifically inhibited protein neddylation, inactivated cullin-RING E3 ligase (CRL), the best-known neddylation substrate, and induced the accumulation of tumor-suppressive CRL substrates in lymphoma cells. Moreover, MLN4924 potently suppressed the growth of lymphoma cells by inducing G2 cell-cycle arrest, followed by apoptosis or senescence in a cell line-dependent manner. MLN4924-induced apoptosis was mediated by intrinsic apoptotic signaling with substantial up-regulation of pro-apoptotic Bik and Noxa as well as down-regulation of anti-apoptotic XIAP, c-IAP1 and c-IAP2, while senescence induction upon neddylation inhibition seemed dependent on the expression of tumor suppressor p21/p27. Together, these findings expand our understanding on how lymphoma cells respond to neddylation inhibition and support the development of neddylation inhibitors (e.g. MLN4924) for the treatment of lymphoma.     

MLN4924, a Novel NEDD8-activating enzyme inhibitor,exhibits antitumor activity and enhances cisplatin-induced cytotoxicity in human cervical carcinoma: in vitro and in vivo study

MLN4924, an inhibitor of NEDD8 activating enzyme (NAE), has been reported to have activity against various malignancies. Here, we investigated the antitumor properties of MLN4924 and MLN4924 in combination with cisplatin on human cervical carcinoma (CC) in vitro and in vivo. Two human CC cell lines, ME-180 and HeLa, were used in this study. The cytotoxic effects of MLN4924 and/or cisplatin were measured by cell viability (MTT), proliferation (BrdU incorporation), apoptosis (flow cytometry with annexin V-FITC labeling), and the expression of cell apoptosis-related proteins (Western blotting). In vivo efficacy was determined in Nu/Nu nude mice with ME-180 and HeLa xenografts. The results showed that MLN4924 elicited viability inhibition, anti-proliferation and apoptosis in human CC cells, accompanied by activations of apoptosis-related molecules and Bid, Bcl-2 phosphorylation interruption, and interference with cell cycle regulators. Moreover, MLN4924 caused an endoplasmic reticulum stress response (caspase-4, ATF-4 and CHOP activations) and expression of other cellular stress molecules (JNK and c-Jun activations). Additionally, MLN4924 suppressed growth of CC xenografts in nude mice. Furthermore, we demonstrated that MLN4924 potentiated cisplatin-induced cytotoxicity in CC cells with activation of caspases. Consistently with this, MLN4924 significantly enhanced cisplatin-induced growth inhibition of CC xenografts. Together, these findings suggest that MLN4924 alone or in combination with cisplatin is of value in treating human CCs.     

NEDD8-targeting drug MLN4924 elicits DNA rereplication by stabilizing Cdt1 in S phase, triggering checkpoint activation, apoptosis, and senescence in cancer cells

MLN4924 is a first-in-class experimental cancer drug that inhibits the NEDD8-activating enzyme, thereby inhibiting cullin-RING E3 ubiquitin ligases and stabilizing many cullin substrates. The mechanism by which MLN4924 inhibits cancer cell proliferation has not been defined, although it is accompanied by DNA rereplication and attendant DNA damage. Here we show that stabilization of the DNA replication factor Cdt1, a substrate of cullins 1 and 4, is critical for MLN4924 to trigger DNA rereplication and inhibit cell proliferation. Even only 1 hour of exposure to MLN4924, which was sufficient to elevate Cdt1 for 4-5 hours, was found to be sufficient to induce DNA rereplication and to activate apoptosis and senescence pathways. Cells in S phase were most susceptible, suggesting that MLN4924 will be most toxic on highly proliferating cancers. Although MLN4924-induced cell senescence seems to be dependent on induction of p53 and its downstream effector p21(Waf1), we found that p53(-/-) and p21(-/-) cells were even more susceptible than wild-type cells to MLN4924. Our results suggested that apoptosis, not senescence, might be more important for the antiproliferative effect of MLN4924. Furthermore, our findings show that transient exposure to this new investigational drug should be useful for controlling p53-negative cancer cells, which often pose significant clinical challenge.     

Editor's choice: Suppression of glioblastoma by targeting the overactivated protein neddylation pathway

Background

The neddylation pathway has been recently identified as an attractive anticancer target, and MLN4924, a specific NEDD8-activating enzyme inhibitor, has been developed as a first-in-class anticancer agent. However, neither the status of the neddylation pathway in glioblastoma (GBM) nor the effect of MLN4924 against GBM has been systematically investigated yet.

Methods

To measure the activation state of the neddylation pathway in GBM, expression of the NEDD8-activating enzyme (E1), NEDD8-conjugating enzyme (E2), and global protein neddylation in GBM tumor tissues versus adjacent tissues were examined by immunoblotting analysis and immunohistochemistry staining. To assess the therapeutic efficacy of neddylation inhibition in GBM, cell proliferation in vitro and tumor growth in vivo were determined upon neddylation inhibition by MLN4924, an investigational NEDD8-activating enzyme inhibitor.

Results

The neddylation pathway was overactivated in a majority of GBM tumor tissues when compared with adjacent normal tissues. The upregulation of this pathway in GBM tissues was positively correlated with high-grade disease and postoperative recurrence but was negatively associated with patient overall survival. MLN4924 treatment inhibited cullin neddylation, inactivated cullin-RING E3 ligase, and led to the accumulation of tumor-suppressive cullin-RING E3 ligase substrates to trigger cell-cycle arrest and senescence or apoptosis in a cell-line dependent manner. Moreover, inhibition of neddylation by MLN4924 significantly suppressed tumor growth in an orthotopic xenograft model of human GBM.

Conclusion

Our study indicates that an overactivated neddylation pathway may be involved in GBM progression and that inhibition of this oncogenic pathway is a potentially new therapeutic approach for GBM.     

High Efficiency Apoptosis Induction in Breast Cancer Cell Lines by MLN4924/2DG Co-Treatment

2-deoxy-D-Glucose (2DG) causes cytotoxicity in cancer cells by disrupting thiol metabolism. It is an effectivecomponent in therapeutic strategies. It targets the metabolism of cancer cells with glycolysis inhibitory activity.On the other hand, MLN4924, a newly discovered investigational small molecule inhibitor of NAE (NEDD8activating enzyme), inactivates SCF E3 ligase and causes accumulation of its substrates which triggers apoptosis.Combination of these components might provide a more efficient approach to treatment. In this research,2DG and MLN4924 were co-applied to breast cancer cells (MCF-7 and SKBR-3) and cytotoxic and apoptoticactivity were evaluated the by Micro culture tetrazolium test (MTT), TUNEL and ELISA methods. Caspase3and Bcl2 genes expression were evaluated by real time Q-PCR methods. The results showed that MLN4924 andMLN4924/2DG dose-dependently suppressed the proliferation of MCF7 and SKBR-3 cells. Cell survival of breastcancer cells exposed to the combination of 2DG/MLN4924 was decreased significantly compared to controls(p<0.05), while 2DG and MLN4924 alone had less pronounced effects on the cells. The obtained results suggestthat 2DG/MLN4924 is much more efficient in breast cancer cell lines with enhanced cytotoxicity via inducing aapoptosis cell signaling gene, caspase-3.