Targeting the Tumour Vasculature: Exploitation of Low Oxygenation and Sensitivity to NOS Inhibition by Treatment with a Hypoxic Cytotoxin

Many cancer research efforts focus on exploiting genetic-level features that may be targeted for therapy. Tissue-level features of the tumour microenvironment also represent useful therapeutic targets. Here we investigate the presence of low oxygen tension and sensitivity to NOS inhibition of tumour vasculature as potential tumour-specific features that may be targeted by hypoxic cytotoxins, a class of therapeutics currently under investigation. We have previously demonstrated that tirapazamine (TPZ) mediates central vascular dysfunction in tumours. TPZ is a hypoxic cytotoxin that is also a competitive inhibitor of NOS. Here we further investigated the vascular-targeting activity of TPZ by combining it with NOS inhibitor L-NNA, or with low oxygen content gas breathing. Tumours were analyzed via multiplex immunohistochemical staining that revealed irreversible loss of perfusion and enhanced tumour cell death when TPZ was combined with either low oxygen or a NOS inhibitor. Tumour growth rate was reduced by TPZ + NOS inhibition, and tumours previously resistant to TPZ-mediated vascular dysfunction were sensitized by low oxygen breathing. Additional mapping analysis suggests that tumours with reduced vascular-associated stroma may have greater sensitivity to these effects. These results indicate that poorly oxygenated tumour vessels, also being abnormally organized and with inadequate smooth muscle, may be successfully targeted for significant anti-cancer effects by inhibition of NOS and hypoxia-activated prodrug toxicity. This strategy illustrates a novel use of hypoxia-activated cytotoxic prodrugs as vascular targeting agents, and also represents a novel mechanism for targeting tumour vessels.     

Colorectal Carcinoma Growth Inhibition by Dietary Care Combined with Probiotic Intervention through Targeting NRP2 Expression

Doklady Biochemistry and Biophysics - The present study investigated the effect of probiotics on inhibition of colorectal tumor growth in vivo and as anti-proliferative agent in vitro....     

Inhibition of Pediatric Glioblastoma Tumor Growth by the Anti-Cancer Agent OKN-007 in Orthotopic Mouse Xenografts

Pediatric glioblastomas (pGBM), although rare, are one of the leading causes of cancer-related deaths in children, with tumors essentially refractory to existing treatments. Here, we describe the use of conventional and advanced in vivo magnetic resonance imaging (MRI) techniques to assess a novel orthotopic xenograft pGBM mouse (IC-3752GBM patient-derived culture) model, and to monitor the effects of the anti-cancer agent OKN-007 as an inhibitor of pGBM tumor growth. Immunohistochemistry support data is also presented for cell proliferation and tumor growth signaling. OKN-007 was found to significantly decrease tumor volumes (p<0.05) and increase animal survival (p<0.05) in all OKN-007-treated mice compared to untreated animals. In a responsive cohort of treated animals, OKN-007 was able to significantly decrease tumor volumes (p<0.0001), increase survival (p<0.001), and increase diffusion (p<0.01) and perfusion rates (p<0.05). OKN-007 also significantly reduced lipid tumor metabolism in responsive animals [(Lip1.3 and Lip0.9)-to-creatine ratio (p<0.05)], as well as significantly decrease tumor cell proliferation (p<0.05) and microvessel density (p<0.05). Furthermore, in relationship to the PDGFRα pathway, OKN-007 was able to significantly decrease SULF2 (p<0.05) and PDGFR-α (platelet-derived growth factor receptor-α) (p<0.05) immunoexpression, and significantly increase decorin expression (p<0.05) in responsive mice. This study indicates that OKN-007 may be an effective anti-cancer agent for some patients with pGBMs by inhibiting cell proliferation and angiogenesis, possibly via the PDGFRα pathway, and could be considered as an additional therapy for pediatric brain tumor patients.     

Targeting Glioma Stem Cells by Functional Inhibition of a Prosurvival OncomiR-138 in Malignant Gliomas

Malignant gliomas are the most aggressive forms of?brain tumors, associated with high rates of morbidity and mortality. Recurrence and tumorigenesis are attributed to a subpopulation of tumor-initiating glioma stem cells (GSCs) that are intrinsically resistant to therapy. Initiation and progression of gliomas have been linked to alterations in microRNA expression. Here, we report the identification of microRNA-138 (miR-138) as a molecular signature of GSCs and demonstrate a vital role for miR-138 in?promoting growth and survival of bona fide tumor-initiating cells with self-renewal potential. Sequence-specific functional inhibition of miR-138 prevents tumorsphere formation in?vitro and impedes tumorigenesis in?vivo. We delineate the components of the miR-138 regulatory network by loss-of-function analysis to identify specific regulators of apoptosis. Finally, the higher expression of miR-138 in GSCs compared to non-neoplastic tissue and association with tumor recurrence and survival highlights the clinical significance of miR-138 as a prognostic biomarker and a therapeutic target for treatment of malignant gliomas.     

Overcoming Amino-Nogo-induced Inhibition of Cell Spreading and Neurite Outgrowth by 12-O-Tetradecanoylphorbol-13-acetate-type Tumor Promoters

The N-terminal domain of NogoA, called amino-Nogo, inhibits axonal outgrowth and cell spreading via a largely unknown mechanism. In the present study, we show that amino-Nogo decreases Rac1 activity and inhibits fibroblast spreading. 12-O-Tetradecanoylphorbol-13-acetate-type tumor promoters, such as phorbol 12-myristate 13-acetate (PMA) and teleocidin, increase Rac1 activity and overcome the amino-Nogo-induced inhibition of cell spreading. The stimulating effect of tumor promoters on cell spreading requires activation of protein kinase D and the subsequent activation of Akt1. Furthermore, we identified Akt1 as a new signaling component of the amino-Nogo pathway. Akt1 phosphorylation is decreased by amino-Nogo. Activation of Akt1 with a cell-permeable peptide, TAT-TCL1, blocks the amino-Nogo inhibition. Finally, we provide evidence that these signaling pathways operate in neurons in addition to fibroblasts. Our results suggest that activation of protein kinase D and Akt1 are approaches to promote axonal regeneration after injury.     

MicroRNA-326 Functions as a Tumor Suppressor in Glioma by Targeting the Nin One Binding Protein (NOB1)

Malignant glioma is the most common type of primary brain tumor in adults, characterized by rapid tumor growth and infiltration of tumor cells throughout the brain. Alterations in the activity of the 26S proteasome have been associated with malignant glioma cells, although the specific defects have not been identified. Recently, microRNA-326 (miR-326) was shown to play an important role in glioblastoma and breast cancer, but the underlying molecular mechanisms remain unclear. In the present study, the human Nin one binding protein (NOB1) was identified as a direct target of miR-326 and a potential oncogene in human glioma. Similar to NOB1 silencing by shRNA, overexpression of miR-326 in human glioma cell lines (A172 and U373) caused cell cycle arrest at the G1 phase, delayed cell proliferation and enhanced apoptosis. MiR-326 inhibited colony formation in soft agar and decreased growth of a xenograft tumor model, suggesting that miR-326 and NOB1 are required for tumorigenesis in vitro and in vivo. Furthermore, these processes were shown to involve the MAPK pathway. NOB1 overexpression in human glioma samples was detected by Affymetrix array analysis, and NOB1 mRNA and protein levels were shown to be increased in high-grade glioma compared to low-grade glioma and normal brain tissue. Furthermore, high levels of NOB1 were associated with unfavorable prognosis of glioma patients. Taken together, these results indicate that miR-326 and NOB1 may play an important role in the development of glioma.     

2-Bromopalmitate Reduces Protein Deacylation by Inhibition of Acyl-Protein Thioesterase Enzymatic Activities

S-acylation, the covalent attachment of palmitate and other fatty acids on cysteine residues, is a reversible post-translational modification that exerts diverse effects on protein functions. S-acylation is catalyzed by protein acyltransferases (PAT), while deacylation requires acyl-protein thioesterases (APT), with numerous inhibitors for these enzymes having already been developed and characterized. Among these inhibitors, the palmitate analog 2-brompalmitate (2-BP) is the most commonly used to inhibit palmitoylation in cells. Nevertheless, previous results from our laboratory have suggested that 2-BP could affect protein deacylation. Here, we further investigated in vivo and in vitro the effect of 2-BP on the acylation/deacylation protein machinery, with it being observed that 2-BP, in addition to inhibiting PAT activity in vivo, also perturbed the acylation cycle of GAP-43 at the level of depalmitoylation and consequently affected its kinetics of membrane association. Furthermore, 2-BP was able to inhibit in vitro the enzymatic activities of human APT1 and APT2, the only two thioesterases shown to mediate protein deacylation, through an uncompetitive mechanism of action. In fact, APT1 and APT2 hydrolyzed both the monomeric form as well as the micellar state of the substrate palmitoyl-CoA. On the basis of the obtained results, as APTs can mediate deacylation on membrane bound and unbound substrates, this suggests that the access of APTs to the membrane interface is not a necessary requisite for deacylation. Moreover, as the enzymatic activity of APTs was inhibited by 2-BP treatment, then the kinetics analysis of protein acylation using 2-BP should be carefully interpreted, as this drug also inhibits protein deacylation.     

Inhibition of Cyclooxygenase-2 Reduces Hypothalamic Excitation in Rats with Adriamycin-Induced Heart Failure

Background

The paraventricular nucleus (PVN) of the hypothalamus plays an important role in the progression of heart failure (HF). We investigated whether cyclooxygenase-2 (COX-2) inhibition in the PVN attenuates the activities of sympathetic nervous system (SNS) and renin-angiotensin system (RAS) in rats with adriamycin-induced heart failure.

Methodology/Principal Finding

Heart failure was induced by intraperitoneal injection of adriamycin over a period of 2 weeks (cumulative dose of 15 mg/kg). On day 19, rats received intragastric administration daily with either COX-2 inhibitor celecoxib (CLB) or normal saline. Treatment with CLB reduced mortality and attenuated both myocardial atrophy and pulmonary congestion in HF rats. Compared with the HF rats, ventricle to body weight (VW/BW) and lung to body weight (LW/BW) ratios, heart rate (HR), left ventricular end-diastolic pressure (LVEDP), left ventricular peak systolic pressure (LVPSP) and maximum rate of change in left ventricular pressure (LV±dp/dtmax) were improved in HF+CLB rats. Angiotensin II (ANG II), norepinephrine (NE), COX-2 and glutamate (Glu) in the PVN were increased in HF rats. HF rats had higher levels of ANG II and NE in plasma, higher level of ANG II in myocardium, and lower levels of ANP in plasma and myocardium. Treatment with CLB attenuated these HF-induced changes. HF rats had more COX-2-positive neurons and more corticotropin releasing hormone (CRH) positive neurons in the PVN than did control rats. Treatment with CLB decreased COX-2-positive neurons and CRH positive neurons in the PVN of HF rats.

Conclusions

These results suggest that PVN COX-2 may be an intermediary step for PVN neuronal activation and excitatory neurotransmitter release, which further contributes to sympathoexcitation and RAS activation in adriamycin-induced heart failure. Treatment with COX-2 inhibitor attenuates sympathoexcitation and RAS activation in adriamycin-induced heart failure.     

Exquisite Tumor Targeting by Salmonella A1-R in Combination with Caffeine and Valproic Acid Regresses an Adult Pleomorphic Rhabdomyosarcoma Patient-Derived Orthotopic Xenograft Mouse Model

Adult pleomorphic rhabdomyosarcoma (RMS) is a rare and malignant mesenchymal tumor. Recently, we developed a patient-derived orthotopic xenograft (PDOX) model of adult pleomorphic RMS. In the present study, we evaluated the efficacy of tumor-targeting Salmonella typhimurium (S. typhimurium) A1-R combined with caffeine (CAF) and valproic acid (VPA) on the adult RMS PDOX. An adult pleomorphic RMS cell line was established from the PDOX model. Cell survival after exposure to CAF and VPA was assessed, and the IC₅₀ value was calculated for each drug. The RMS PDOX models were randomized into five groups: untreated control; tumor treated with cyclophosphamide (CPA); tumor treated with CAF + VPA; tumor treated with S. typhimurium A1-R; and tumor treated with S. typhimurium A1-R + CAF + VPA. Tumor size and body weight was measured twice a week. VPA caused a concentration-dependent cytocidal effect. A synergistic effect of combination treatment with CAF was observed against the RMS cell line. For the in vivo study, all treatments significantly inhibited tumor growth compared with the untreated control. S. typhimurium A1-R combined with VPA and CAF was significantly more effective than CPA, VPA combined with CAF, or S. typhimurium A1-R alone and significantly regressed the tumor volume compared with day 0. These results suggest that S. typhimurium A1-R together with VPA and CAF could regresses an adult pleomorphic RMS in a PDOX model and therefore has important future clinical potential.     

Vitamin D Inhibits COX-2 Expression and Inflammatory Response by Targeting Thioesterase Superfamily Member 4

Inadequate vitamin D status has been linked to increased risk of type 2 diabetes and cardiovascular disease. Inducible cyclooxygenase (COX) isoform COX-2 has been involved in the pathogenesis of such chronic inflammatory diseases. We found that the active form of vitamin D, 1,25(OH)₂D produces dose-dependent inhibition of COX-2 expression in murine macrophages under both basal and LPS-stimulated conditions and suppresses proinflammatory mediators induced by LPS. Administration of 1,25(OH)₂D significantly alleviated local inflammation in a carrageenan-induced paw edema mouse model. Strikingly, the phosphorylation of both Akt and its downstream target IκBα in macrophages were markedly suppressed by 1,25(OH)₂D in the presence and absence of LPS stimulation through up-regulation of THEM4 (thioesterase superfamily member 4), an Akt modulator protein. Knockdown of both vitamin D receptor and THEM4 attenuated the inhibitory effect of 1,25(OH)₂D on COX-2 expression in macrophages. A functional vitamin D-responsive element in the THEM4 promoter was identified by chromatin immunoprecipitation and luciferase reporter assay. Our results indicate that vitamin D restrains macrophage-mediated inflammatory processes by suppressing the Akt/NF-κB/COX-2 pathway, suggesting that vitamin D supplementation might be utilized for adjunctive therapy for inflammatory disease.     

磁共振波谱成像结合扩散加权成像在脑胶质瘤及脑转移瘤鉴别诊断中的意义

目的:评估磁共振波谱成像(Proton Magnetic Resonance Spectroscopy,1H-MRS)联合磁共振扩散加权成像(Diffusion Weighted Imaging,DWI)在鉴别脑胶质瘤及孤立的脑转移瘤中的作用。方法:应用3.0T磁共振扫描仪,对临床手术确诊及组织病理学诊断证实的49例脑肿瘤患者(35例多形性胶质母细胞瘤,14例脑转移瘤)进行常规磁共振成像、磁共振波谱成像及磁共振扩散加权成像,并并对获得的数据进一步测量瘤内及瘤周区的代谢比、N-乙酰天门冬氨酸(NAA)、胆碱(Cho)、肌酸(Cr)值以及表观弥散系数(ADC值),分析两肿瘤组之间不同参数的统计学差异。此外,我们研究了感兴趣区域(ROI)的大小对肿瘤区域的病变扩散性能潜在影响。结果:胶质母细胞瘤瘤周N-乙酰天门冬氨酸(NAA)、肌酸(Cr),胆碱(Cho)/Cr,Cho/NAA和r CBV显著高于颅内转移瘤(P0.05);ADC值在两肿瘤组之间无显著差异(P0.05)。结论:在瘤周区1H-MRS有助于鉴别胶质母细胞瘤与单发的脑转移瘤。在瘤内扩散性的定量特性依赖ROI大小的设置。     

In Vivo Bioluminescent Imaging of Irradiated Orthotopic Pancreatic Cancer Xenografts in Nonobese Diabetic-Severe Combined Immunodeficient Mice: A Novel Method for Targeting and Assaying Efficacy of Ionizing Radiation

Adenocarcinoma of the pancreas is a lethal malignancy, and better models to study tumor behavior in vivo are needed for the development ofmore effective therapeutics. Ionizing radiation is a treatment modality that is commonly used in the clinical setting, in particular, for locally confined disease; however, good model systems to study the effect of ionizing radiation in orthotopic tumors have not been established. In an attempt to create clinically relevant models for studying treatments directed against pancreatic cancer, we have defined a methodology to measure the effect of varying doses of radiation in established human pancreatic cancer orthotopic xenografts using two different pancreatic cancer cell lines (Panc-1 and BXPC3) infected with a lentiviral vector expressing CMV promoter-driven luciferase to allow bioluminescence imaging of live animals in real time. Quantifiable photon emission from luciferase signaling in vivo correlated well with actual tumor growth. Bioluminescence imaging of the established pancreatic xenografts was used to direct delivery of radiation to the orthotopic tumors and minimize off-target adverse effects. Growth delay was observed with schedules in the range of 7.5 Gy in five fractions to 10 Gy in four fractions, whereas doses 3 Gy or higher produced toxic adverse effects. In conclusion, we describe a model in which the effects of ionizing radiation, alone or in combination with other therapeutics, in orthotopic xenografts, can be studied.     

研究miR-219下调TGFBR2影响ENDMT途径抑制急性心肌梗死

目的: 主要是miR-219通过对TGFBR2调控机制,介导ENDMT途径缓解急性心肌梗死的发展。方法: qRT-PCR检测AMI患者及AMI小鼠血清中miR-219的表达量;过microRNA靶基因数据库TargetScan进行筛选预测;萤光素酶报告基因法及qRT-PCR分析TGFBR2与miR-219的调控机制;通过心脏超声心动图检测AMI小鼠心肌注射miR-219慢病毒4周后的血分数(LVEF);采用qRT-PCR检测心肌注射miR-219慢病毒的AMI小鼠中Nppa 的mRNA的表达量;通过Masson’s trichrome染色法检测小鼠4周后左心室纤维化变化;使用α平滑肌肌动蛋白(α-SMA)对小鼠左室切片进行免疫组化分析;通过Western blot检测P-smad2、P-smad3及TGFBR2缺氧诱导蛋白磷酸化的表达水平。结果: miR-219对AMI有调控作用;miR-219可抑制TGFBR2的mRNA表达,而miR-219 inhibitor可以抑制这种下调效果,miR-219对TGFBR2具有抑制调控性;miR-219可抑制急性心肌梗死的进程,促进梗死心肌功能的恢复;miR-219能促进AMI小鼠心肌组织血管的新生和成熟,最终心脏收缩能力上升,心功能恢复;miR-219能抑制TGFBR2抑制EndMT途径,导致缓解AMI的病理进程。结论: miR-219能通过抑制TGFBR2影响EndMT途径,心肌纤维化减少,促进血管的新生和成熟,心功能恢复,抑制AMI的病理发展。     

Inhibition of Elongation Factor-2 Kinase Augments the Antitumor Activity of Temozolomide against Glioma

Background

Glioblastoma multiforme (GBM), the most common form of brain cancer with an average survival of less than 12 months, is a highly aggressive and fatal disease characterized by survival of glioma cells following initial treatment, invasion through the brain parenchyma and destruction of normal brain tissues, and ultimately resistance to current treatments. Temozolomide (TMZ) is commonly used chemotherapy for treatment of primary and recurrent high-grade gliomas. Nevertheless, the therapeutic outcome of TMZ is often unsatisfactory. In this study, we sought to determine whether eEF-2 kinase affected the sensitivity of glioma cells to treatment with TMZ.

Methodology/Principal Findings

Using RNA interference approach, a small molecule inhibitor of eEF-2 kinase, and in vitro and in vivo glioma models, we observed that inhibition of eEF-2 kinase could enhance sensitivity of glioma cells to TMZ, and that this sensitizing effect was associated with blockade of autophagy and augmentation of apoptosis caused by TMZ.

Conclusions/Significance

These findings demonstrated that targeting eEF-2 kinase can enhance the anti-glioma activity of TMZ, and inhibitors of this kinase may be exploited as chemo-sensitizers for TMZ in treatment of malignant glioma.     

miR-216b-5p靶向调控BTN3A2促进胶质瘤细胞LN-229的迁移以及侵袭能力

大量证据表明microRNA（miRNA）通过靶向调控靶基因的表达从而在肿瘤侵袭与转移中发挥重要作用。然而关于microRNA-216b-5p (miR-216b-5p )通过靶向嗜乳脂蛋白第3亚家族膜蛋白A2（butyrophilin subfamily 3 member A2,BTN3A2）促进胶质瘤侵袭与转移的机制尚不明确。本研究通过GSE15824与GSE4290差异表达分析筛选出同时在2个芯片中表达上调的BTN3A2（P＜0.05）。生存曲线结果显示,高表达BTN3A2病人总生存期明显下降（P＜0.001）。表达量分析结果显示,BTN3A2表达随WHO分级升高而升高（P＜0.05）,同时1p/19q未联合缺失与IDH突变型病人BTN3A2表达升高（P＜0.001）。基因集富集分析（gene set enrichment analysis,GSEA）结果显示,BTN3A2与众多癌症相关通路有关（P＜0.05）;Western印迹结果显示,BTN3A2在7例胶质瘤组织和胶质瘤细胞系U87、U251和LN-229中表达上调,过表达miR-216b-5p （miR-216b-5p mimics）后BTN3A2蛋白表达水平降低;Transwell结果显示,转染BTN3A2干扰质粒（si-BTN3A2）和miR-216b-5p mimics后可以抑制LN 229细胞体外迁移与侵袭能力（P＜0.05）;在线预测网站证实,miR-216b-5p 为BTN3A2潜在靶基因;生存曲线结果显示,与低表达miR-216b-5p 病人相比,高表达病人生存率明显上调（P=0.025）;荧光定量RT PCR结果显示,miR-216b-5p 在胶质瘤U87、U251和LN-229细胞中表达下降（P＜0.05）;双荧光素酶结果显示,BTN3A2存在与miR-216b-5p 的结合靶点(P<005);综上所述,BTN3A2可能通过结合miR-216b-5p 促进胶质瘤细胞LN 229的迁移以及侵袭。     

A Combination of Radiation and the Hypoxia-Activated Prodrug Evofosfamide (TH-302) is Efficacious against a Human Orthotopic Pancreatic Tumor Model

This study was designed to investigate the effect of single-dose radiation therapy (RT) in combination with evofosfamide (TH-302), a hypoxia-activated prodrug, in a pre-clinical model of pancreatic cancer. AsPC1 tumors were implanted orthotopically in the pancreas of nude mice. Tumors were treated with 15 Gy of RT, using a 1 cm diameter field, and delivered as a continuous arc. Image-guidance to center the field on the tumor was based on CT imaging with intraperitoneal contrast. Evofosfamide (100 mg/kg, i.p.) was administered 3 hours before RT. Tumor volumes were measured using ultrasound, and regrowth curves were plotted. Tumor hypoxia and cell proliferation were measured using pimonidazole and the thymidine analog EdU, respectively. In vitro clonogenic assays were performed. Tumors were shown to contain substantial areas of hypoxia, as calculated by percent pimonidazole staining. Evofosfamide was active in these tumors, as demonstrated by a significant reduction in uptake of the thymidine analog EdU. This effect was visible in oxygenated tissue, consistent with the previously reported bystander effects of evofosfamide. RT produced significant regrowth delay, as did evofosfamide. The combination of both agents produced a growth delay that was at least equal to the sum of the two treatments given separately. The improvement in tumor response when evofosfamide is combined with RT supports the hypothesis that hypoxia is a cause of radioresistance in high dose RT for pancreatic cancer. Assessing the efficacy and safety of stereotactic radiation treatment and evofosfamide is warranted in patients with locally advanced pancreatic cancer.