Two different specific JNK activators are required to trigger apoptosis or compensatory proliferation in response to Rbf1 in Drosophila

The Jun Kinase (JNK) signaling pathway responds to diverse stimuli by appropriate and specific cellular responses such as apoptosis, differentiation or proliferation. The mechanisms that mediate this specificity remain largely unknown. The core of this signaling pathway, composed of a JNK protein and a JNK kinase (JNKK), can be activated by various putative JNKK kinases (JNKKK) which are themselves downstream of different adaptor proteins. A proposed hypothesis is that the JNK pathway specific response lies in the combination of a JNKKK and an adaptor protein upstream of the JNKK. We previously showed that the Drosophila homolog of pRb (Rbf1) and a mutant form of Rbf1 (Rbf1^D253A) have JNK-dependent pro-apoptotic properties. Rbf1^D253A is also able to induce a JNK-dependent abnormal proliferation. Here, we show that Rbf1-induced apoptosis triggers proliferation which depends on the JNK pathway activation. Taking advantage of these phenotypes, we investigated the JNK signaling involved in either Rbf1-induced apoptosis or in proliferation in response to Rbf1-induced apoptosis. We demonstrated that 2 different JNK pathways involving different adaptor proteins and kinases are involved in Rbf1-apoptosis (i.e. Rac1-dTak1-dMekk1-JNK pathway) and in proliferation in response to Rbf1-induced apoptosis (i.e., dTRAF1-Slipper-JNK pathway). Using a transient induction of rbf1, we show that Rbf1-induced apoptosis activates a compensatory proliferation mechanism which also depends on Slipper and dTRAF1. Thus, these 2 proteins seem to be key players of compensatory proliferation in Drosophila.     

RACK1对硼替佐米诱导的多发性骨髓瘤细胞凋亡及MAPK/ERK通路的影响

目的:探讨蛋白激酶C受体(Receptor for activated C kinase1,RACK1)对硼替佐米(Bortezomi,Bor)诱导的多发性骨髓瘤(Multiple myeloma,MM)细胞凋亡及MAPK/ERK通路的影响。方法:选取6例岳阳市第一人民医院收治的MM患者及6名正常体检者,用实时荧光定量PCR检测血浆及人MM细胞系中RACK1 m RNA的表达。将MM细胞分为3组:对照组(不干预)、Bor组(75n M的Bor干预12 h)和Bor+siRACK1组(RACK1 si RNA转染24 h后再行Bor干预)。CCK-8法检测各组细胞中的细胞存活率,Hoechest 33342染色检测细胞凋亡,Western Blot检测MAPK/ERK通路相关蛋白表达。结果:与正常体检者相比,MM患者血浆及MM细胞系中RACK1 m RNA表达显著增加(P0.05)。Bor作用12 h、24 h和48 h可显著降低MM细胞的存活率(P0.05)。与对照组相比,Bor组和Bor+siRACK1组细胞存活率显著降低,Bor+siRACK1组细胞存活率明显高于Bor组(P0.05)。Hoechest 33342染色显示对照组细胞核染色均一,未见凋亡小体,Bor组见少量凋亡小体,而Bor+siRACK1组细胞见大量凋亡小体,表现为核固缩或碎块状;与对照组相比,Bor组和Bor+siRACK1组细胞中多发性骨髓瘤细胞凋亡率显著增加(P0.05),Bor+siRACK1组多发性骨髓瘤细胞凋亡率明显高于Bor组(P0.05)。三组间多发性骨髓瘤细胞凋亡率对比差异有统计学意义(P0.05)。与对照组相比,Bor组和Bor+siRACK1组细胞中p-P38和p-ERK的表达显著降低,而Bor+siRACK1组p-P38和p-ERK的表达低于Bor组(P0.05),3组间P38和ERK的表达对比差异无统计学意义(P0.05)。结论:RACK1沉默可增强Bor诱导的MM细胞凋亡及生长抑制,其机制可能与MAPK/ERK途径抑制有关。     

乙醛脱氢酶2可减少氧化损伤诱导的心肌细胞凋亡

乙醛脱氢酶2 (aldehyde dehydrogenase 2, ALDH2)是线粒体特异性酶,已被证明参与氧化应激诱导的细胞凋亡,而在心肌细胞中的作用知之甚少。本研究旨在通过用特异性ALDH2抑制剂大豆苷抑制ALDH2活性来研究ALDH2在抗霉素A诱导的心肌细胞凋亡中的作用。应用抗霉素A和大豆苷诱导小鼠心肌细胞,然后测定ALDH2酶活性、细胞内活性氧(reactive oxy gen species, ROS)含量和细胞凋亡,应用RT-PCR和蛋白质印迹法(Western blotting)检测ALDH2 m RNA和蛋白表达。结果表明,抗霉素A (40μg/mL)可诱导新生心肌细胞凋亡,而大豆苷(50μmol/L)能有效地抑制ALDH2活性而对细胞凋亡没有影响,并且可显著增强抗霉素A诱导的心肌细胞凋亡(53.72%～71.33%, p<0.05)。与单独用抗霉素A处理的细胞相比,抗霉素A和大豆苷共处理的心肌细胞中活化的丝裂原活化蛋白激酶(mitogen-activated protein kinase, MAPK)信号传导途径(p38-MAPK)的磷酸化也显著增加。本研究初步表明,改变线粒体ALDH2活性可能是减少氧化损伤诱导的心肌细胞凋亡的潜在选择。     

FBXL10 regulates cardiac dysfunction in diabetic cardiomyopathy via the PKC β2 pathway

Diabetic cardiomyopathy (DCM) is a condition associated with significant structural changes including cardiac tissue necrosis, localized fibrosis, and cardiomyocyte hypertrophy. This study sought to assess whether and how FBXL10 can attenuate DCM using a rat streptozotocin (STZ)‐induced DCM model system. In the current study, we found that FBXL10 expression was significantly decreased in diabetic rat hearts. FBXL10 protected cells from high glucose (HG)‐induced inflammation, oxidative stress, and apoptosis in vitro. In addition, FBXL10 significantly activated PKC β2 signaling pathway in H9c2 cells and rat model. The cardiomyocyte‐specific overexpression of FBXL10 at 12 weeks after the initial STZ administration attenuated oxidative stress and inflammation, thereby reducing cardiomyocyte death and preserving cardiac function in these animals. Moreover, FBXL10 protected against DCM via activation of the PKC β2 pathway. In conclusion, FBXL has the therapeutic potential for the treatment of DCM.     

Proteasome Inhibitor PS-341 Effectively Blocks Infection by the Severe Fever with Thrombocytopenia Syndrome Virus

Severe fever with thrombocytopenia syndrome(SFTS) is an emerging hemorrhagic fever disease caused by SFTSV, a newly discovered phlebovirus that is named after the disease. Currently, no effective vaccines or drugs are available for use against SFTSV infection, as our understanding of the viral pathogenesis is limited. Bortezomib(PS-341), a dipeptideboronic acid analog, is the first clinically approved proteasome inhibitor for use in humans. In this study, the antiviral efficacy of PS-341 against SFTSV infection was tested in human embryonic kidney HEK293 T(293 T) cells. We employed four different assays to analyze the antiviral ability of PS-341 and determined that PS-341 inhibited the proliferation of SFTSV in 293 T cells under various treatment conditions. Although PS-341 did not affect the virus absorption, PS-341 treatment within a non-toxic concentration range resulted in a significant reduction of progeny viral titers in infected cells.Dual-luciferase reporter assays and Western blot analysis revealed that PS-341 could reverse the SFTSV-encoded nonstructural protein(NS) mediated degradation of retinoic acid-inducible gene-1(RIG-I), thereby antagonizing the inhibitory effect of NSs on interferons and blocking virus replication. In addition, we observed that inhibition of apoptosis promotes virus replication. These results indicate that targeting of cellular interferon pathways and apoptosis during acute infection might serve as the bases of future therapeutics for the treatment of SFTSV infections.     

Oxymatrine Inhibits Bocavirus MVC Replication,Reduces Viral Gene Expression and Decreases Apoptosis Induced by Viral Infection

Oxymatrine(OMT), as the main active component of Sophoraflavescens, exhibits a variety of pharmacological properties,including anti-oxidative, anti-inflammatory, anti-tumor, and anti-viral activities, and currently is extensively employed to treat viral hepatitis; however, its effects on parvovirus infection have yet to be reported. In the present study, we investigated the effects of OMT on cell viability, virus DNA replication, viral gene expression, cell cycle, and apoptosis in Walter Reed canine cells/3873 D infected with minute virus of canines(MVC). OMT, at concentrations below 4 mmol/L(no cellular toxicity), was found to inhibit MVC DNA replication and reduce viral gene expression at both mRNA and protein levels, which was associated with the inhibition of cell cycle S-phase arrest in early-stage of MVC infection.Furthermore, OMT significantly increased cell viability, decreased MVC-infected cell apoptosis, and reduced the expression of activated caspase 3. Our results suggest that OMT has potential application in combating parvovirus infection.     

Targeting TRAIL

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), also known as Apo2L, has been investigated in the past decade for its promising anticancer activity due to its ability to selectively induce apoptosis in tumoral cells by binding to TRAIL receptors (TRAIL-R). Macromolecules such as agonistic monoclonal antibodies and recombinant TRAIL have not proven efficacious in clinical studies, therefore several small molecules acting as TRAIL-R agonists are emerging in the scientific literature. In this work we focus on systemizing these drug molecules described in the past years, in order to better understand and predict the requirements for a novel anti-tumoral therapy based on the TRAIL-R-induced apoptotic mechanism.     

Synthesis,antiproliferative and apoptosis induction potential activities of novel bis(indolyl)hydrazide-hydrazone derivatives

In recent years, indole-indazolyl hydrazide-hydrazone derivatives with strong cell growth inhibition and apoptosis induction characteristics are being strongly screened for their cancer chemo-preventive potential. In the present study, N-methyl and N,N-dimethyl bis(indolyl)hydrazide-hydrazone analog derivatives were designed, synthesized and allowed to evaluate for their anti-proliferative and apoptosis induction potential against cervical (HeLa), breast (MCF-7 and MDA-MB-231) and lung (A549) cancer cell lines relative to normal HEK293 cells. The MTT assay in conjunction with mitochondrial potential assays and the trypan blue dye exclusion were employed to ascertain the effects of the derivatives on the cancer cells. Further, mechanistic studies were conducted on compound 14a to understand the biochemical mechanisms and functional interactions with various signaling pathways triggered in HeLa and MCF-7 cells. Compound 14a induced apoptosis via caspase independent pathway through the participation of mitogen-activated protein kinases (MAPK) such as extracellular signal related kinase (ERK) and p38 as well as p53 pathways. It originates the activation of pro-apoptotic proteins such as Bak and Mcl-1s and also strongly induced the generation of reactive oxygen species. In downstream signaling pathway, activated p53 protein interacted with MAPK pathways, including SAPK/c-Jun N-terminal protein kinase (JNK), p38 and ERK kinases resulting in apoptotic cell death. The involvement of MAPK cascades such as p38, ERK and p38 on compound 14a induced apoptotic cell death was evidenced by the fact that the inclusion of specific inhibitors of p38, ERK1/2 and JNK MAPK (SB2035809, PD98059 and SP600125) prevented the compound 14a towards induced apoptosis. The results clearly showed that MAP kinase cascades were crucial for apoptotic response in compound 14a induced cellular killing and were dependent on p53 activity. Based on the results, compound 14a was identified as a promising candidate for cancer therapeutics and these findings furnish a basis for further in vivo experiments on anti-proliferative activity.     

Raloxifene-encapsulated hyaluronic acid-decorated chitosan nanoparticles selectively induce apoptosis in lung cancer cells

Non-small cell lung cancer (NSCLC) and hepatocellular carcinoma (HCC) are leading causes of cancer mortality and morbidity around the world. Despite the recent advances in their diagnosis and therapy, their prognosis remains poor owing to the development of drug resistance and metastasis. Raloxifene (RX), a drug first used in the treatment of osteoporosis, was recently approved for NSCLC and HCC prevention. Unfortunately, many of the therapies that use RX are likely to become ineffective due to drug resistance. Herein, we developed a novel delivery strategy by utilizing hyaluronic acid (HA) and chitosan (CS) complexation to increase the half-life and activity of RX. Consequently, we explored the pro-apoptotic and cytotoxic effects of RX-HA-CS nanoparticles (NPs) against NSCLC (A549) and HCC (HepG2 and Huh-7) cell lines. The highest entrapment efficiency (EE%) was noted in RX-HA-CS NPs (92%) compared to RX-HA NPs (87.5%) and RX-CS NPs (68%). In addition, RX-HA-CS NPs induced the highest cytotoxicity against A549 cells compared to other platforms. The significant suppression of A549 cell viability was achieved via glucose uptake reduction resulting in diminished bioenergetics of cancer cells and activation of apoptosis via nitric oxide level elevation. This study is the first to assess the efficacy of RX in its HA-CS nano-formulation against lung and liver cancer cells and demonstrated its selective cytotoxic and apoptotic potential against human lung A549 cancer cell line. These findings demonstrate a promising drug delivery system to help mitigate drug resistance in lung cancer.