Notch inhibition restores TRAIL-mediated apoptosis via AP1-dependent upregulation of DR4 and DR5 TRAIL receptors in MDA-MB-231 breast cancer cells

Dysregulation of a lncRNA within the TNFRSF10A locus activates cell death pathways

TNFRSF10A (tumor necrosis factor receptor superfamily member 10A) encodes a cell surface receptor protein involved in apoptotic, necroptotic, and inflammatory pathways. Dysregulation of TNFRSF10A has been implicated in sensitization to apoptosis and to the development of multiple diseases, yet little is known of the AC100861.1 long noncoding RNA (lncRNA) that lies head-to-head with TNFRSF10A. Given its genomic positioning, we sought to investigate the function of AC100861.1, focusing on its potential relationship with TNFRSF10A and the role it may play in death receptor signaling. Using knockdown and overexpression strategies, we probed cell viability and examined transcript and protein-level changes in key genes involved in apoptosis, necroptosis, and inflammation. Decreased cell viability was observed upon TNFRSF10A overexpression, regardless of whether the cells were subjected to the chemical stressor tunicamycin. Similarly, overexpression of AC100861.1 led to increased cell death, with a further increase observed under conditions of cellular stress. Knockdown of TNFRSF10A increased cell death only when the cells were stressed, and AC100861.1 knockdown exhibited no effect on cell death. Neither knockdown nor overexpression of either of these genes greatly affected the expression of the other. Manipulating AC100861.1, however, led to marked changes in the expression of genes involved in necroptosis and inflammatory cell-signaling pathways. Additionally, RNA fluorescence in situ hybridization (RNA-FISH) revealed that the AC100861.1 transcript is localized primarily to the cytoplasm. Together, these data suggest that AC100861.1 may have a role in regulating necroptotic and inflammatory signaling pathways and that this function is separate from changes in TNFRSF10A expression. Given the importance of this genomic locus for cell survival, these data provide insight into the function of a poorly understood lncRNA with potential implications regarding disease pathology and treatment.

Identification of LTBP2 gene polymorphisms and their association with thoracolumbar vertebrae number, body size, and carcass traits in Dezhou donkeys

The number of thoracolumbar vertebrae in Dezhou donkeys varies from 22 to 24 and is associated with body size and carcass traits. In mammals, the latent transforming growth factor beta binding protein 2 (LTBP2) has been found to have some functions in the development of thoracolumbar vertebrae. The relationship between LTBP2 and TLN (the number of thoracolumbar vertebrae) of Dezhou donkeys is yet to be reported. The purposes of this study are as follows: 1) to quantify the effect of thoracolumbar vertebrae number variation of Dezhou donkeys on body size and carcass trait; 2) to study the distribution of single nucleotide variants (SNVs) in the LTBP2 gene of Dezhou donkeys; and 3) to explore whether these SNVs can be used as candidate sites to study the mechanism of Dezhou donkey muti-thoracolumbar vertebrae development. The TLN, body size, and carcass traits of 392 individuals from a Dezhou donkey breed were recorded. All animals were sequenced for LTBP2 using GBTS liquid chip and 16 SNVs were used for further analysis. We then analyzed the relationship between these SNVs with TLN, body size, and carcass traits. The results showed that: 1) c.5547 + 860 C > T, c.5251 + 281 A > C, c.3769 + 40 C > T, and c.2782 + 3975 A > G were complete genetic linkages and significantly associated with thoracic vertebrae number (TN) (p < 0.05) (wild-type homozygotes had more TN than heterozygotes); 2) c.1381 + 768 T > G and c.1381 + 763 G > T were significantly associated with lumber vertebrae number (LN) (p < 0.05); 3) c.1003 + 704 C > T, c.1003 + 651 C > T, c.1003 + 626 A > G, and c.812 + 22526 T > G were significantly associated with chest circumference (CHC), front carcass weight (CWF), after carcass weight (CWA), and carcass weight (CW) (p < 0.05) (wild-type homozygotes were larger than other genotypes in CHC, CWF, CWA, and CW); and 4) the effect of variation is not consistent in c.565 + 11921 A > G, c.565 + 6840 A > G, c.565 + 3453 C > T, and c.494 + 5808 C > T. These results provide useful information that the polymorphism of LTBP2 is significantly associated with TLN, body size, and carcass traits in Dezhou donkeys, which can serve as a molecule marker to improve donkey production performance.

Notch Signalling in Breast Development and Cancer

The Notch signalling pathway is a highly conserved developmental signalling pathway, with vital roles in determining cell fate during embryonic development and tissue homeostasis. Aberrant Notch signalling has been implicated in many disease pathologies, including cancer. In this review, we will outline the mechanism and regulation of the Notch signalling pathway. We will also outline the role Notch signalling plays in normal mammary gland development and how Notch signalling is implicated in breast cancer tumorigenesis and progression. We will cover how Notch signalling controls several different hallmarks of cancer within epithelial cells with sections focussed on its roles in proliferation, apoptosis, invasion, and metastasis. We will provide evidence for Notch signalling in the breast cancer stem cell phenotype, which also has implications for therapy resistance and disease relapse in breast cancer patients. Finally, we will summarise the developments in therapeutic targeting of Notch signalling, and the pros and cons of this approach for the treatment of breast cancer.

Genome-Wide Association Analysis Identified BMPR1A as a Novel Candidate Gene Affecting the Number of Thoracic Vertebrae in a Large White × Minzhu Intercross Pig Population

Simple Summary

The number of thoracic vertebrae (NTV) and number of vertebrae (NV) varies among pig breeds with a high correlation of about 0.8. It is important to discover variants associated with the NTV by considering the effect of the NV in pig. The results suggest that regulation variants on SSC7 might play crucial roles in the NTV and the FOS on SSC7 should be further studied as a critical candidate gene. In addition, BMPR1A was identified as a novel candidate gene affecting the NTV in pigs.

Abstract

The number of vertebrae (NV), especially the number of thoracic vertebrae (NTV), varies among pig breeds. The NTV is controlled by vertebral segmentation and the number of somites during embryonic development. Although there is a high correlation between the NTV and NV, studies on a fixed NV have mainly considered the absolute numbers of thoracic vertebrae instead of vertebral segmentation. Therefore, this study aimed to discover variants associated with the NTV by considering the effect of the NV in pigs. The NTV and NV of 542 F2 individuals from a Large White × Minzhu pig crossbreed were recorded. All animals were genotyped for VRTN g.19034 A > C, LTBP2 c.4481A > C, and 37 missense or splice variants previously reported in a 951-kb interval on SSC7 and 147 single nucleotide polymorphisms (SNPs) on SSC14. To identify NTV-associated SNPs, we firstly performed a genome-wide association study (GWAS) using the Q + K (population structure + kinship matrix) model in TASSEL. With the NV as a covariate, the obtained data were used to identify the SNPs with the most significant genome-wide association with the NTV by performing a GWAS on a PorcineSNP60K Genotyping BeadChip. Finally, a conditional GWAS was performed by fixing this SNP. The GWAS showed that 31 SNPs on SSC7 have significant genome-wide associations with the NTV. No missense or splice variants were found to be associated with the NTV significantly. A linkage disequilibrium analysis suggested the existence of quantitative trait loci (QTL) in a 479-Kb region on SSC7, which contained a critical candidate gene FOS for the NTV in pigs. Subsequently, a conditional GWAS was performed by fixing M1GA0010658, the most significant of these SNPs. Two SNPs in BMPR1A were found to have significant genome-wide associations and a significant dominant effect. The leading SNP, S14_87859370, accounted for 3.86% of the phenotypic variance. Our study uncovered that regulation variants in FOS on SSC7 and in BMPR1A on SSC14 might play important roles in controlling the NTV, and thus these genetic factors may be harnessed for increasing the NTV in pigs.

Notch-Inflammation Networks in Regulation of Breast Cancer Progression

Members of the Notch family and chronic inflammation were each separately demonstrated to have prominent malignancy-supporting roles in breast cancer. Recent investigations indicate that bi-directional interactions that exist between these two pathways promote the malignancy phenotype of breast tumor cells and of their tumor microenvironment. In this review article, we demonstrate the importance of Notch-inflammation interplays in malignancy by describing three key networks that act in breast cancer and their impacts on functions that contribute to disease progression: (1) Cross-talks of the Notch pathway with myeloid cells that are important players in cancer-related inflammation, focusing mainly on macrophages; (2) Cross-talks of the Notch pathway with pro-inflammatory factors, exemplified mainly by Notch interactions with interleukin 6 and its downstream pathways (STAT3); (3) Cross-talks of the Notch pathway with typical inflammatory transcription factors, primarily NF-κB. These three networks enhance tumor-promoting functions in different breast tumor subtypes and act in reciprocal manners, whereby Notch family members activate inflammatory elements and vice versa. These characteristics illustrate the fundamental roles played by Notch-inflammation interactions in elevating breast cancer progression and propose that joint targeting of both pathways together may provide more effective and less toxic treatment approaches in this disease.

Notch and breast cancer metastasis: Current knowledge, new sights and targeted therapy

Breast cancer is the most common type of invasive cancer in females and metastasis is one of the major causes of breast cancer-associated mortality. Following detachment from the primary site, disseminated tumor cells (DTCs) enter the bloodstream and establish secondary colonies during the metastatic process. An increasing amount of studies have elucidated the importance of Notch signaling in breast cancer metastasis; therefore, the present review focuses on the mechanisms by which Notch contributes to the occurrence of breast cancer DTCs, increases their motility, establishes interactions with the tumor microenvironment, protects DTCs from host surveillance and finally facilitates secondary colonization. Identification of the underlying mechanisms of Notch-associated breast cancer metastasis will provide additional insights that may contribute towards the development of novel Notch-targeted therapeutic strategies, which may aid in reducing metastasis, culminating in an improved patient prognosis.

Rhamnetin induces apoptosis in human breast cancer cells via the miR-34a/Notch-1 signaling pathway

The present study aimed to investigate whether rhamnetin induced apoptosis in human breast cancer cells and the underlying molecular mechanism of this anti cancer effect. The treatment of MCF-7 cells with rhamnetin was able to significantly inhibit cell proliferation and induce caspase-3/9 activity in a dose- and time-dependent manner, compared with untreated cells. In addition, treatment with rhamnetin was able to significantly promote the expression of p53 protein and microRNA (miR-)34a compared with untreated cells. The treatment with rhamnetin also suppressed the expression of Notch1 protein in MCF-7 cells compared with untreated cells. Subsequently, miR-24a expression was promoted in rhamnetin-treated MCF-7 cells using a miR-34a plasmid. The overexpression of miR-34a was able to significantly inhibit cell viability and induce caspase-3/9 activity in MCF-7 cells following treatment with rhamnetin. Furthermore, the overexpression of miR-34a was able to significantly promote the expression of p53 protein and miR-34a, and suppress the expression of Notch1 protein in rhamnetin-treated MCF-7 cells. Therefore, the results of the present study demonstrated that rhamnetin induced apoptosis in human breast cancer cells via the miR-34a/Notch-1 signaling pathway.

AP-1 confers resistance to anti-cancer therapy by activating XIAP

The underlying cause of treatment failure in many cancer patients is intrinsic and acquired resistance to chemotherapy. Recently, histone deacetylase (HDAC) inhibitors have developed into a promising cancer treatment. However, resistance mechanism induced by HDAC inhibitors remains largely unknown. Here we report that a HDAC inhibitor, JNJ-2648158 induced transcription of XIAP by activating AP-1 expression, which conferring resistance to chemotherapeutics. Our results showed that high expression of c-Fos caused by HDAC inhibitor promoted AP-1 formation during acquired resistance towards chemo-drugs, indicating an extremely poor clinical outcome in breast cancers and liver cancers. Our study reveals a novel regulatory mechanism towards chemo-drug resistance, and suggests that XIAP may serve as a potential therapeutic target in those chemo-resistant cancer cells.

TRAIL DR5-CTSB crosstalk participates in breast cancer autophagy initiated by SAHA

To investigate the ability of SAHA-induced TRAIL DR5-CTSB crosstalk to initiate the breast cancer autophagy, RTCA assay was performed to assess the effect of SAHA on breast cancer cells, and western blot and ELISA were used to verify the inductive effects on expression of CTSB. Breast cancer cells were transfected with TRAIL DR5 siRNA to block the function of TRAIL DR5. Cell viability and apoptosis of breast cancer cells were analyzed using a muse cell analyzer. The distribution of LC3-II in TRAIL DR5-silenced breast cancer cells treated with SAHA was observed by immunofluorescence microscopy, the mRNA levels of autophagy-related genes were detected by RNA microarray, and the activity of autophagy-related signaling pathways was screened by MAPK antibody array. Results indicated that SAHA did indeed repress the growth of breast cancer cell lines with inducing CTSB expression. Western blot and ELISA results indicated that TRAIL DR5 was involved in the expression of CTSB in SAHA-induced breast cancer cells. Cell viability and apoptosis assays showed that the inactivation of TRAIL DR5 can significantly inhibit the effects of SAHA. An immunofluorescence assay indicated that, with SAHA treatment, MDA-MB-231 and MCF-7 cells underwent apparent morphological changes. While SAHA was added in the TRAIL-DR5 blocked cells, the distribution of LC3-II signal was dispersed, the intensity of fluorescence signal was weaker than that of SAHA alone. RNA array indicated that SAHA significantly increased mRNA expression of autophagy marker LC3A/B whereas the change was significantly reversed in TRAIL DR5-silenced cells. The results of MAPK antibody array showed that SAHA and TRAIL DR5 could affect the activity of AKT1, AKT2, and TOR protein in breast cancer cells. These results provide more evidence that SAHA may stimulate TRAIL DR5-CTSB crosstalk, influence the activity of downstream TOR signalling pathway mainly through the AKTs pathway, and initiate the autophagy of breast cancer cells.

Journey of TRAIL from Bench to Bedside and its Potential Role in Immuno-Oncology

Induction of apoptosis in cancer cells has increasingly been the focus of many therapeutic approaches in oncology field. Since its identification as a TNF family member, TRAIL (TNF-related apoptosis-inducing ligand) paved a new path in apoptosis inducing cancer therapies. Its selective ability to activate extrinsic and intrinsic cell death pathways in cancer cells only, independently from p53 mutations responsible for conventional therapeutics resistance, spotted TRAIL as a potent cancer apoptotic agent. Many recombinant preparations of TRAIL and death receptor targeting monoclonal antibodies have been developed and being tested pre-clinically and clinically both as a single agent and in combinations. Of note, the monoclonal antibodies were not the only type of antibodies developed to target TRAIL receptors. Recent technology has brought forth several single chain variable domains (scFv) designs fused recombinantly to TRAIL as well. Also, it is becoming progressively more understandable that field of nanotechnology has revolutionized cancer diagnosis and therapy. The recent breakthroughs in materials science and protein engineering have helped considerably in strategically loading drugs into nanoparticles or conjugating drugs to their surface. In this review we aim to comprehensively highlight the molecular knowledge of TRAIL in the context of its pathway, receptors and resistance factors. We also aim to review the clinical trials that have been done using TRAIL based therapies and to review various scFv designs, the arsenal of nano-carriers and molecules available to selectively target tumor cells with TRAIL.

Notch-1 Confers Chemoresistance in Lung Adenocarcinoma to Taxanes through AP-1/microRNA-451 Mediated Regulation of MDR-1

We previously demonstrated that expression of Notch-1 is associated with poor prognosis in lung adenocarcinoma (LAD) patients. The aim of this study is to reveal whether Notch-1 was associated with Taxanes-resistant LAD and, the underlying mechanisms. We collected 39 patients of advanced LAD treated with Taxanes and found that positive Notch-1 expression is closely related to LAD lymph node metastasis, recurrence and poorer prognosis, and Notch-1 acts as an independent poor prognostic factor in LAD by multivariate analysis with Cox regression model. Then, by using the Docetaxel (DTX)-resistant LAD cell lines that we established previously, we found that Notch-1 contributes to resistance of LAD cells to DTX in vitro, and inhibition of Notch-1 sensitizes LAD to DTX in vivo. We further demonstrated that Notch-1 mediates chemoresistance response and strengthens proliferation capacity in LAD cells partially through negative regulation of miR-451 by transcription factor AP-1. Moreover, we found that MDR-1 is a direct target of miR-451 and influences chemoresistance of LAD cells. Taken together, our data revealed a novel Notch-1/AP-1/miR-451/MDR-1 signaling axis, and suggested a new therapeutic strategy of combining DTX with Notch inhibitors to treat DTX-resistant LAD.

Inhibition of γ-secretase activity synergistically enhances tumour necrosis factor-related apoptosis-inducing ligand induced apoptosis in T-cell acute lymphoblastic leukemia cells via upregulation of death receptor 5

T-cell acute lymphoblastic leukemia (T-ALL) is a rare and aggressive hematopoietic malignancy prone to relapse and drug resistance. Half of all T-ALL patients exhibit mutations in Notch1, which leads to aberrant Notch1 associated signaling cascades. Notch1 activation is mediated by the γ-secretase cleavage of the Notch1 receptor into the active intracellular domain of Notch1 (NCID). Clinical trials of γ-secretase small molecule inhibitors (GSIs) as single agents for the treatment of T-ALL have been unsuccessful. The present study demonstrated, using immunofluorescence and western blotting, that blocking γ-secretase activity in T-ALL cells with N-[(3,5-difluorophenyl) acetyl]-L-alanyl-2-phenyl] glycine-1,1-dimethylethyl ester (DAPT) downregulated NCID and upregulated the tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) death receptor 5 (DR5). Upregulation of DR5 restored the sensitivity of T-ALL cells to TRAIL. Combination index revealed that the combined treatment of DAPT and TRAIL synergistically enhanced apoptosis compared with treatment with either drug alone. TRAIL combined with the clinically evaluated γ-secretase inhibitor 3-[(1r, 4s)-4-(4-chlorophenylsulfonyl)-4-(2, 5-difluorophenyl) cyclohexyl] propanoic acid (MK-0752) also significantly enhanced TRAIL-induced cell death compared with either drug alone. DAPT/TRAIL apoptotic synergy was dependent on the extrinsic apoptotic pathway and was associated with a decrease in BH3 interacting-domain death agonist and x-linked inhibitor of apoptosis. In conclusion, γ-secretase inhibition represents a potential therapeutic strategy to overcome TRAIL resistance for the treatment of T-ALL.

Role of nanotechnology and gene delivery systems in TRAIL-based therapies

Since its identification as a member of the tumour necrosis factor (TNF) family, TRAIL (TNF-related apoptosis-inducing ligand) has emerged as a new avenue in apoptosis-inducing cancer therapies. Its ability to circumvent the chemoresistance of conventional therapeutics and to interact with cancer stem cells (CSCs) self-renewal pathways, amplified its potential as a cancer apoptotic agent. Many recombinant preparations of this death ligand and monoclonal antibodies targeting its death receptors have been tested in monotherapy and combinational clinical trials. Gene therapy is a new approach for cancer treatment which implies viral or non-viral functional transgene induction of apoptosis in cancer cells or repair of the underlying genetic abnormality on a molecular level. The role of this approach in overcoming the traditional barriers of radiation and chemotherapeutics systemic toxicity, risk of recurrence, and metastasis made it a promising platform for cancer treatment. The recent first Food Drug Administration (FDA) approved oncolytic herpes virus for melanoma treatment brings forth the potency of the cancer gene therapy approach in the future. Many gene delivery systems have been studied for intratumoural TRAIL gene delivery alone or in combination with chemotherapeutic agents to produce synergistic cancer cytotoxicity. However, there still remain many obstacles to be conquered for this different gene delivery systems. Nanomedicine on the other hand offers a new frontier for clinical trials and biomedical research. The FDA approved nanodrugs motivates horizon exploration for other nanoscale designed particles’ implications in gene delivery. In this review we aim to highlight the molecular role of TRAIL in apoptosis and interaction with cancer stem cells (CSCs) self-renewal pathways. Finally, we also aim to discuss the different roles of gene delivery systems, mesenchymal cells, and nanotechnology designs in TRAIL gene delivery.

A bispecific fusion protein and a bifunctional enediyne-energized fusion protein consisting of TRAIL, EGFR peptide ligand, and apoprotein of lidamycin against EGFR and DR4/5 show potent antitumor activity

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) mainly induces apoptosis through the extrinsic death receptor-induced pathway by ligation with death receptor 4 (DR4) and death receptor 5 (DR5). On the basis of the antitumor activity to cancer cells and no cytotoxity to normal cells of TRAIL and the target of the epidermal growth factor receptor (EGFR) ligand peptide, the study constructed a new bispecific fusion protein and a new bifunctional enediyne-energized fusion protein and investigated their antitumor efficacy. Bispecific fusion protein Ec-LDP-TRAIL showed potent binding activity to cancer cell lines with a high expression of EGFR or DR4/DR5 such as A431 and H460 cells, whereas poor binding activity to NIH/3T3 cells with low expressing EGFR and DR4/DR5. Ec-LDP-TRAIL also showed more potent cytotoxicity to A431 and H460 cells than Ec-LDP, which could result from the TRAIL-inducing apoptosis. Results of an in-vivo efficacy study showed that Ec-LDP-TRAIL at a dose of 10 mg/kg decreased the growth of epidermoid carcinoma A431 xenografts by 80.19% (P < 0.01) on day 26. Immunohistochemical detection of nuclear antigen factor Ki-67 suggested that Ec-LDP-TRAIL effectively induced cell necrosis and inhibited cell proliferation of tumor. From IC50 values, bispecific and bifunctional energized fusion protein Ec-LDP-TRAIL-AE was more potent and selective in its cytotoxicity against different carcinoma cell lines than corresponding lidamycin in vitro and induction of the cleavage of poly(ADP-ribose)polymerase was observed in A431 cells treated with Ec-LDP-TRAIL-AE and lidamycin, respectively. Ec-LDP-TRAIL-AE also significantly inhibited the growth of A431 xenografts in a nude mouse model. These properties suggested that Ec-LDP-TRAIL and Ec-LDP-TRAIL-AE may be promising candidates for targeted cancer therapy.

The secreted protein acidic and rich in cysteine is a critical mediator of cell death program induced by WIN/TRAIL combined treatment in osteosarcoma cells

Secreted protein acidic and rich in cysteine (SPARC) is a multi-functional protein which modulates cell-cell and cell-matrix interactions. In cancer cells, SPARC behaves as a tumor promoter in a number of tumors, but it can also act as a tumor suppressor factor. Our previous results showed that the synthetic cannabinoid WIN55,212-2 (WIN), a potent cannabinoid receptor agonist, is able to sensitize osteosarcoma MG63 cells to TNF-related apoptosis-inducing ligand (TRAIL)-induced apoptosis which is accompanied with endoplasmic reticulum (ER)-stress induction and the increase in autophagic markers. In the present investigation, we studied the role of SPARC in WIN/TRAIL-induced apoptosis demonstrating that WIN increased the level of SPARC protein and mRNA in a time-dependent manner. This event was functional to WIN/TRAIL-dependent apoptosis as demonstrated by RNA interfering analysis which indicated that SPARC-silenced cells were less sensitive to cytotoxic effects induced by the combined treatment. Our experiments also demonstrate that SPARC interacts with caspase-8 thus probably favoring its translocation to plasma membrane and the activation of extrinsic apoptotic pathway. In conclusion, to the best of our knowledge, our results are the first to show that WIN-dependent increase in the level of SPARC plays a critical role in sensitizing osteosarcoma cells to TRAIL action.

Marine Drugs Regulating Apoptosis Induced by Tumor Necrosis Factor-Related Apoptosis-Inducing Ligand (TRAIL)

Marine biomass diversity is a tremendous source of potential anticancer compounds. Several natural marine products have been described to restore tumor cell sensitivity to TNF-related apoptosis inducing ligand (TRAIL)-induced cell death. TRAIL is involved during tumor immune surveillance. Its selectivity for cancer cells has attracted much attention in oncology. This review aims at discussing the main mechanisms by which TRAIL signaling is regulated and presenting how marine bioactive compounds have been found, so far, to overcome TRAIL resistance in tumor cells.

Inhibition of Notch1 signaling overcomes resistance to the death ligand Trail by specificity protein 1-dependent upregulation of death receptor 5

The Notch1 signaling pathway contributes to tumorigenesis by influencing differentiation, proliferation and apoptosis. Here, we demonstrate that inhibition of the Notch1 signaling pathway sensitizes glioblastoma cell lines and glioblastoma initiating cells to apoptosis induced by the death ligand TRAIL. This sensitization occurs through transcriptional upregulation of the death receptor 5 (DR5, TRAIL-R2). The increase in DR5 expression is abrogated by concomitant repression of the transcription factor Sp1, which directly binds to the DR5 promoter in the absence of Notch1 as revealed by chromatin immunoprecipitation. Consistent with these findings, Notch1 inhibition resulted in increased DR5 promoter activity, which was impaired by mutation of one out of two Sp1-binding sites within the proximal DR5 promoter. Moreover, we demonstrate that JNK signaling contributes to the regulation of DR5 expression by Notch1. Taken together, our results identify Notch1 as key driver for TRAIL resistance and suggest Notch1 as a promising target for anti-glioblastoma therapy.

Calmodulin antagonists promote TRA-8 therapy of resistant pancreatic cancer

Pancreatic cancer is highly malignant with limited therapy and a poor prognosis. TRAIL-activating therapy has been promising, however, clinical trials have shown resistance and limited responses of pancreatic cancers. We investigated the effects of calmodulin(CaM) antagonists, trifluoperazine(TFP) and tamoxifen(TMX), on TRA-8-induced apoptosis and tumorigenesis of TRA-8-resistant pancreatic cancer cells, and underlying mechanisms. TFP or TMX alone did not induce apoptosis of resistant PANC-1 cells, while they dose-dependently enhanced TRA-8-induced apoptosis. TMX treatment enhanced efficacy of TRA-8 therapy on tumorigenesis in vivo. Analysis of TRA-8-induced death-inducing-signaling-complex (DISC) identified recruitment of survival signals, CaM/Src, into DR5-associated DISC, which was inhibited by TMX/TFP. In contrast, TMX/TFP increased TRA-8-induced DISC recruitment/activation of caspase-8. Consistently, caspase-8 inhibition blocked the effects of TFP/TMX on TRA-8-induced apoptosis. Moreover, TFP/TMX induced DR5 expression. With a series of deletion/point mutants, we identified CaM antagonist-responsive region in the putative Sp1-binding domain between -295 to -300 base pairs of DR5 gene. Altogether, we have demonstrated that CaM antagonists enhance TRA-8-induced apoptosis of TRA-8-resistant pancreatic cancer cells by increasing DR5 expression and enhancing recruitment of apoptotic signal while decreasing survival signals in DR5-associated DISC. Our studies support the use of these readily available CaM antagonists combined with TRAIL-activating agents for pancreatic cancer therapy.

Expression of Notch1 Correlates with Breast Cancer Progression and Prognosis

Various studies have evaluated the significance of Notch1 expression in breast cancer, but the results have ever been disputed. By using 21 studies involving 3867 patients, this meta-analysis revealed that the expression of Notch1 was significantly higher in breast cancer than in normal tissues (OR=7.21; 95%CI, 4.7-11.07) and that higher Notch1 expression was associated with transition from ductal carcinoma in situ (DCIS) to invasive cancer (OR=3.75; 95% CI, 1.8-7.78). Higher Notch1 activity was observed in the basal subtype of breast cancer (OR=2.53; 95% CI, 1.18-5.43). Moreover, patients with Notch1 overexpression exhibited significantly worse overall and recurrence-free survival. Our meta-analysis suggests that Notch inhibitors may be useful in blocking the early progression of DCIS and that the outcomes of clinical trials for Notch1-targeting therapeutics could be improved by the molecular stratification of breast cancer patients.

Molecular signalling in hepatocellular carcinoma: Role of and crosstalk among WNT/ß-catenin, Sonic Hedgehog, Notch and Dickkopf-1

Hepatocellular carcinoma is the sixth most common cancer worldwide. In the majority of cases, there is evidence of existing chronic liver disease from a variety of causes including viral hepatitis B and C, alcoholic liver disease and nonalcoholic steatohepatitis. Identification of the signalling pathways used by hepatocellular carcinoma cells to proliferate, invade or metastasize is of paramount importance in the discovery and implementation of successfully targeted therapies. Activation of Wnt/β-catenin, Notch and Hedgehog pathways play a critical role in regulating liver cell proliferation during development and in controlling crucial functions of the adult liver in the initiation and progression of human cancers. β-catenin was identified as a protein interacting with the cell adhesion molecule E-cadherin at the cell-cell junction, and has been shown to be one of the most important mediators of the Wnt signalling pathway in tumourigenesis. Investigations into the role of Dikkopf-1 in hepatocellular carcinoma have demonstrated controversial results, with a decreased expression of Dickkopf-1 and soluble frizzled-related protein in various cancers on one hand, and as a possible negative prognostic indicator of hepatocellular carcinoma on the other. In the present review, the authors focus on the Wnt⁄β-catenin, Notch and Sonic Hedgehog pathways, and their interaction with Dikkopf-1 in hepatocellular carcinoma.

Tissue invasion and metastasis: Molecular, biological and clinical perspectives

Cancer is a key health issue across the world, causing substantial patient morbidity and mortality. Patient prognosis is tightly linked with metastatic dissemination of the disease to distant sites, with metastatic diseases accounting for a vast percentage of cancer patient mortality. While advances in this area have been made, the process of cancer metastasis and the factors governing cancer spread and establishment at secondary locations is still poorly understood. The current article summarizes recent progress in this area of research, both in the understanding of the underlying biological processes and in the therapeutic strategies for the management of metastasis. This review lists the disruption of E-cadherin and tight junctions, key signaling pathways, including urokinase type plasminogen activator (uPA), phosphatidylinositol 3-kinase/v-akt murine thymoma viral oncogene (PI3K/AKT), focal adhesion kinase (FAK), β-catenin/zinc finger E-box binding homeobox 1 (ZEB-1) and transforming growth factor beta (TGF-β), together with inactivation of activator protein-1 (AP-1) and suppression of matrix metalloproteinase-9 (MMP-9) activity as key targets and the use of phytochemicals, or natural products, such as those from Agaricus blazei, Albatrellus confluens, Cordyceps militaris, Ganoderma lucidum, Poria cocos and Silybum marianum, together with diet derived fatty acids gamma linolenic acid (GLA) and eicosapentanoic acid (EPA) and inhibitory compounds as useful approaches to target tissue invasion and metastasis as well as other hallmark areas of cancer. Together, these strategies could represent new, inexpensive, low toxicity strategies to aid in the management of cancer metastasis as well as having holistic effects against other cancer hallmarks.

Two death-inducing human TRAIL receptors to target in cancer: similar or distinct regulation and function?

The emergence during evolution of two tumour necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) receptors, receptor-1/DR4 and -2/DR5, able to induce apoptosis has raised the question whether they differ in function and regulation, which is of key importance for selecting either DR4 or DR5 selective pro-apoptotic agents for cancer treatment. In this review we found practically no information regarding possible differences in DR4 and DR5 function based on structural differences. On the other hand, a panel of different DR4 or DR5 selective pro-apoptotic agonists have been developed that were explored for efficacy in different tumour types in a large number of studies. Leukemic cells appear mainly sensitive for DR4-induced apoptosis, contrasting the situation in other tumour types that show heterogeneity in receptor preference and, in some cases, a slight overall preference for DR5. Both receptors were found to mediate intracellular stress-induced apoptosis, although this is most frequently reported for DR5. Interestingly, DR5 was also found to transmit non-apoptotic signalling in resistant tumour cells and recently nuclear localization and a role in microRNA maturation has been described. DR4 expression is most heavily regulated by promoter methylation, intracellular trafficking and post-translational modifications. DR5 expression is predominantly regulated at the transcriptional level, which may reflect its ability to respond to cellular stressors. It will be important to further increase our understanding of the mechanisms determining TRAIL receptor preference in order to select the appropriate TRAIL receptor selective agonists for therapy, and to develop novel strategies to enhance apoptosis activation in tumours.

Notch1 silencing inhibits proliferation and invasion in SGC‑7901 gastric cancer cells

Downregulation of Notch1 has been shown to exert antineoplastic effects in vivo and in vitro. However, the role of the Notch1 gene in the proliferative and invasive ability of gastric cancer cells is not clear. In this study, we investigated the effect of Notch1 gene silencing on the proliferation and invasion of gastric cancer SGC‑7901 cells. Small interfering RNA (siRNA) targeting Notch1 was transfected into SGC‑7901 cells using Lipofectamine 2000. Proliferation of SGC‑7901 cells was then determined by the MTT assay. Notch1 mRNA expression was determined by reverse transcription‑polymerase chain reaction (RT‑PCR). Invasion of the SGC‑7901 cells was detected by the Transwell assay. The protein levels of cyclin D1, cyclin A1 and cyclin-dependent kinase 2 (CDK2) were determined by western blotting. The mRNA levels of matrix metalloproteinase‑2 (MMP‑2) and cyclooxygenase‑2 (COX‑2) were determined by RT‑PCR. Compared to the control group, the Notch1 mRNA level was significantly decreased following transfection. The growth and invasion rates of SGC‑7901 cells were significantly reduced after Notch1 silencing. Additionally, the expression of cyclin D1 and cyclin A1 proteins and of the MMP‑2 and COX‑2 mRNAs was markedly attenuated. From these results, it was concluded that Notch1 gene silencing inhibits the proliferation of gastric SGC‑7901 cells by decreasing the expression of cyclins D1 and A1, and reduces the invasive ability of SGC‑7901 cells through the downregulation of MMP‑2 and COX‑2 genes. Thus, silencing of the Notch1 pathway may be a novel approach in the treatment of gastrointestinal cancer.