Effect of DAPT, a gamma secretase inhibitor, on tumor angiogenesis in control mice

Understanding the Modulatory Role of E2012 on the γ-Secretase-Substrate Interaction

Allosteric modulation plays a critical role in enzyme functionality and requires a deep understanding of the interactions between the active and allosteric sites. γ-Secretase (GS) is a key therapeutic target in the treatment of Alzheimer's disease (AD), through its role in the synthesis of amyloid β peptides that accumulate in AD patients. This study explores the structure and dynamic effects of GS modulation by E2012 binding, employing well-tempered metadynamics and conventional molecular dynamics simulations across three binding scenarios: (1) GS enzyme with and without L458 inhibitor, (2) the GS-substrate complex together with the modulator E2012 in two different binding modes, and (3) E2012 interacting with a C99 substrate fragment. Our findings reveal that the presence of L458 induces conformational changes that contribute to stabilization of the GS enzyme dynamics, previously reported as a key factor that allowed the resolution of the cryo-EM structure and the enhanced binding of E2012. Furthermore, we identified the most favorable binding site for E2012 within the GS-substrate complex, uncovering significant modulatory effects and a complex network of interactions that influence the position of the substrate for catalysis. In addition, we explore a potential substrate-modulator binding before the formation of the enzyme-substrate complex. The insights gained from our study emphasize the importance of these interactions in the development of potential therapeutic interventions that target the functionality of the GS enzyme in AD.

Exosomal long non-coding RNA TRPM2-AS promotes angiogenesis in gallbladder cancer through interacting with PABPC1 to activate NOTCH1 signaling pathway

BACKGROUND

Abnormal angiogenesis is crucial for gallbladder cancer (GBC) tumor growth and invasion, highlighting the importance of elucidating the mechanisms underlying this process. LncRNA (long non-coding RNA) is widely involved in the malignancy of GBC. However, conclusive evidence confirming the correlation between lncRNAs and angiogenesis in GBC is lacking.

METHODS

LncRNA sequencing was performed to identify the differentially expressed lncRNAs. RT-qPCR, western blot, FISH, and immunofluorescence were used to measure TRPM2-AS and NOTCH1 signaling pathway expression in vitro. Mouse xenograft and lung metastasis models were used to evaluate the biological function of TRPM2-AS during angiogenesis in vivo. EDU, transwell, and tube formation assays were used to detect the angiogenic ability of HUVECs. RIP, RAP, RNA pull-down, dual-luciferase reporter system, and mass spectrometry were used to confirm the interaction between TRPM2-AS, IGF2BP2, NUMB, and PABPC1.

RESULTS

TRPM2-AS was upregulated in GBC tissues and was closely related to angiogenesis and poor prognosis in patients with GBC. The high expression level and stability of TRPM2-AS benefited from m6A modification, which is recognized by IGF2BP2. In terms of exerting pro-angiogenic effects, TRPM2-AS loaded with exosomes transported from GBC cells to HUVECs enhanced PABPC1-mediated NUMB expression inhibition, ultimately promoting the activation of the NOTCH1 signaling pathway. PABPC1 inhibited NUMB mRNA expression through interacting with AGO2 and promoted miR-31-5p and miR-146a-5p-mediated the degradation of NUMB mRNA. The NOTCH signaling pathway inhibitor DAPT inhibited GBC tumor angiogenesis, and TRPM2-AS knockdown enhanced this effect.

CONCLUSIONS

TRPM2-AS is a novel and promising biomarker for GBC angiogenesis that promotes angiogenesis by facilitating the activation of the NOTCH1 signaling pathway. Targeting TRPM2-AS opens further opportunities for future GBC treatments.

GRWD1 Over-Expression Promotes Gastric Cancer Progression by Activating Notch Signaling Pathway via Up-Regulation of ADAM17

BACKGROUND

Glutamate-rich WD repeat containing 1 (GRWD1) is over-expressed in a variety of malignant tumors and is considered to be a potential oncogene. However, its mechanism of action in gastric cancer (GC) is still unclear.

METHODS

Data analysis, Immunohistochemistry, and Western Blot (WB) were performed to verify the expression of GRWD1 in GC and para-cancerous tissues. The association between GRWD1 expression and tumor size, tissue differentiation, lymph node metastasis, TNM stage, and prognosis was analyzed according to the high and low expression levels of GRWD1. The relationship between GRWD1 and Notch pathway was verified by data analysis and WB. The effects of GRWD1 on the proliferation, migration, and invasion of GC cells were verified by cell proliferation, migration, and invasion assays. We confirmed that the high expression of GRWD1 promoted the proliferation of GC cells in vivo through the tumor formation assay in nude mice.

RESULTS

The expression of GRWD1 was higher in GC tissues than in para-cancerous tissues, and its expression was positively correlated with tumor size, lymph node metastasis, and TNM stage, but negatively correlated with differentiation grade and prognosis. GRWD1 over-expression increased ADAM metallopeptidase domain 17 (ADAM17) expression and promoted Notch1 intracellular domain (NICD) release to promote GC cell proliferation, migration, and invasion in vitro. Results from animal studies have shown that high GRWD1 expression could promote GC cell proliferation in vivo by activating the Notch signaling pathway.

CONCLUSION

GRWD1 promotes GC progression through ADAM17-dependent Notch signaling, and GRWD1 may be a novel tumor marker and therapeutic target.

Targeting of Notch, IL-1, and leptin has therapeutic potential in xenograft colorectal cancer

Background/aim

Colorectal cancer (CRC) is a fatal malignancy type and its occurence still needs to be explored mechanistically. Notch, IL-1, and leptin crosstalk is reported to play a role in the proliferation, migration, and expression of proangiogenic molecules. In this study, we aimed to investigate the effect of inhibition of Notch, IL-1, and leptin on CRC.

Materials and methods

To generate colorectal cancer tumor xenografts, 1 × 107 cells from exponentially growing cultures of HCT-15 cells were injected subcutaneously, at the axillary region of the left and right rear flanks of forty NOD.CB17-Prkdcscid/J (NOD/SCID) female mice. The mice were then monitored for the development of tumors and were randomly divided into five groups when tumor sizes reached a volume of approximately 150 mm3. Mice were used to determine the effectiveness of the gamma-secretase inhibitor (DAPT, Notch inhibitor), the interleukin-1 receptor antagonist (Anakinra) and the leptin receptor antagonist (Allo aca) against tumor growth. The mice were euthanized by CO2 inhalation immediately after the treatments finished, and all efforts were made to minimize suffering. Tumors were excissed for RT-PCR and histological analysis.

Results

There is an intact Notch, IL-1, and leptin signaling axis, and in vivo antagonism of Notch, IL-1, and leptin affects mRNA and protein expression of inflammatory and angiogenic molecules.

Conclusion

Present data suggest that targeting Notch, IL-1, and leptin may be possesses therapeutic potential in CRC.

Rgma-Induced Neo1 Proteolysis Promotes Neural Tube Morphogenesis

Neuroepithelial cell (NEC) elongation is one of several key cell behaviors that mediate the tissue-level morphogenetic movements that shape the neural tube (NT), the precursor of the brain and spinal cord. However, the upstream signals that promote NEC elongation have been difficult to tease apart from those regulating apico-basal polarity and hingepoint formation, due to their confounding interdependence. The Repulsive Guidance Molecule a (Rgma)/Neogenin 1 (Neo1) signaling pathway plays a conserved role in NT formation (neurulation) and is reported to regulate both NEC elongation and apico-basal polarity, through signal transduction events that have not been identified. We examine here the role of Rgma/Neo1 signaling in zebrafish (sex unknown), an organism that does not use hingepoints to shape its hindbrain, thereby enabling a direct assessment of the role of this pathway in NEC elongation. We confirm that Rgma/Neo1 signaling is required for microtubule-mediated NEC elongation, and demonstrate via cell transplantation that Neo1 functions cell autonomously to promote elongation. However, in contrast to previous findings, our data do not support a role for this pathway in establishing apical junctional complexes. Last, we provide evidence that Rgma promotes Neo1 glycosylation and intramembrane proteolysis, resulting in the production of a transient, nuclear intracellular fragment (NeoICD). Partial rescue of Neo1a and Rgma knockdown embryos by overexpressing neoICD suggests that this proteolytic cleavage is essential for neurulation. Based on these observations, we propose that RGMA-induced NEO1 proteolysis orchestrates NT morphogenesis by promoting NEC elongation independently of the establishment of apical junctional complexes.SIGNIFICANCE STATEMENT The neural tube, the CNS precursor, is shaped during neurulation. Neural tube defects occur frequently, yet underlying genetic risk factors are poorly understood. Neuroepithelial cell (NEC) elongation is essential for proper completion of neurulation. Thus, connecting NEC elongation with the molecular pathways that control this process is expected to reveal novel neural tube defect risk factors and increase our understanding of NT development. Effectors of cell elongation include microtubules and microtubule-associated proteins; however, upstream regulators remain controversial due to the confounding interdependence of cell elongation and establishment of apico-basal polarity. Here, we reveal that Rgma-Neo1 signaling controls NEC elongation independently of the establishment of apical junctional complexes and identify Rgma-induced Neo1 proteolytic cleavage as a key upstream signaling event.

The Notch Signaling System Is Involved in the Regulation of Reparative Angiogenesis in the Zone of Stasis

The Notch pathway ligand Delta-like 4 (Dll4) functions as an antiangiogenic factor, inhibiting vascular endothelial growth factor (VEGF)-induced angiogenesis. This function is documented in tumor and embryonic vasculature. However, its implication in burn wounds remains unexplored. Our objective was to explore the involvement of the Notch in the healing of zone of stasis burns. We hypothesized that anti-Dll4 therapy would prevent progressive necrosis in the stasis zone by promoting angiogenesis. Burns were created in 21 rats using the comb burn model. The Notch inhibitor N-[N-(3,5-difluorophenacetyl)-1-alanyl]-S-phenylglycine-t-butyl-ester was administered in the treatment group. Controls were given the same amount of solvent. Seven days after the burn, skin samples were evaluated for VEGF and Dll4 gene expressions. Immunohistochemical analysis was used for the assessment of vascular density, endothelial Dll4 expression, and apoptosis count. Histologic grading of tissue damage was performed. Circulating levels of VEGF and Dll4 were determined. VEGF and Dll4 mRNA levels were found to be simultaneously induced after the burn. In the treatment group, a significant increase in the number of vessels was observed. However, gross evaluation documented an expansion of necrosis to the zone of stasis with marked activation of apoptosis. Histologic assessment showed that the resultant vascular overgrowth was accompanied by extensive edema and abundant infiltration of leukocytes. We provide evidence for the involvement of Notch in the regulation of angiogenesis in zone of stasis burns.

Gamma secretase inhibitors: a patent review (2013 - 2015)

INTRODUCTION

Gamma secretase (GS) is an intricate and multi-subunits complex, and it can cut various transmembrane proteins. Now it is a therapeutic target for a number of diseases. However, due to some side effects, the clinical development of GSI is not successful. Therefore, searching for effective GSIs has become a key point in drug discovery. Areas covered: This review discusses the structure and function of GS and various types of GSIs. And this article seeks to give an overview of the patents or applications published from 2013 to 2015 in which novel chemical classes are claimed to inhibit the GS. Expert opinion: Firstly, further understanding the structure and function of GS to elucidate the disease mechanism and develop AD therapies is urgent. Secondly, if the bioequivalence, pharmacokinetics and selectivity can be improved greatly, some failed clinical inhibitors still can become the promising compounds for clinical trials. Thirdly, some weaknesses are exposed during the development of GSI, especially the insufficient potency, low brain penetration and poor selectivity. Finally, to find potent and selective GSI is the major direction in future. Moreover, to find new indications and dosing regimens in a trial of GSIs also can be seen as new ways.

Role of Jagged1-Hey1 Signal in Angiotensin II-induced Impairment of Myocardial Angiogenesis

BACKGROUND

Angiotensin II (Ang II) is a major contributor to the development of heart failure. However, the molecular and cellular mechanisms that underlie this process remain elusive. Inadequate angiogenesis in the myocardium leads to a transition from cardiac hypertrophy to dysfunction, and our previous study showed that Ang II significantly impaired the angiogenesis response. The current study was designed to examine the role of Jagged1-Notch signaling in the effect of Ang II during impaired angiogenesis and cardiac hypertrophy.

METHODS

Ang II was subcutaneously infused into 8-week-old male C57BL/6 mice at a dose of 200 ng·kg-1·min-1 for 2 weeks using Alzet micro-osmotic pumps. N-[N-(3, 5-difluorophenacetyl)-L-alanyl]-S-phenylglycine tert-butyl ester (DAPT), a γ-secretase inhibitor, was injected subcutaneously during Ang II infusion at a dose of 10.0 mg·kg-1·d-1. Forty mice were divided into four groups (n = 10 per group): control group; Ang II group, treated with Ang II; DAPT group, treated with DAPT; and Ang II + DAPT group, treated with both Ang II and DAPT. At the end of experiments, myocardial (left ventricle [LV]) tissue from each experimental group was evaluated using immunohistochemistry, Western blotting, and real-time polymerase chain reaction. Data were analyzed using one-way analysis of variance test followed by the least significant difference method or independent samples t-test.

RESULTS

Ang II treatment significantly induced cardiac hypertrophy and impaired the angiogenesis response compared to controls, as shown by hematoxylin and eosin (HE) staining and immunohistochemistry for CD31, a vascular marker (P < 0.05 for both). Meanwhile, Jagged1 protein was significantly increased, but gene expression for both Jag1 and Hey1 was decreased in the LV following Ang II treatment, compared to that in controls (relative ratio for Jag1 gene: 0.45 ± 0.13 vs. 0.84 ± 0.15; relative ratio for Hey1 gene: 0.51 ± 0.08 vs. 0.91 ± 0.09; P < 0.05). All these cellular and molecular effects induced by Ang II in the hearts of mice were reduced by DAPT treatment. Interestingly, Ang II stimulated Hey1, a known Notch target, but did not affect the expression of Hey2, another Notch target gene.

CONCLUSIONS

A Jagged1-Hey1 signal might mediate the impairment of angiogenesis induced by Ang II during cardiac hypertrophy.

Enhancement of vascular endothelial growth factor's angiogenic capacity by the therapeutic modulation of notch signalling improves tram flap survival in rats submitted to nicotine

BACKGROUND

Smoke of cigarettes, and specifically nicotine, has been shown to diminish pedicled transverse rectus abdominis musculocutaneous (TRAM) flap survival. Considering that Notch signalling through its ligand Delta-like 4 (Dll4) functions as anti-angiogenic factor by inhibiting the pro-angiogenic effects of vascular endothelial growth factor (VEGF), it is hypothesised that inhibition of the Notch would promote angiogenesis and increase TRAM flap survival in rats submitted to nicotine.

METHODS

Twenty rats were treated with nicotine for 28 days preoperatively. Thereafter, a pedicled TRAM flap was created in all animals. The Notch inhibitor N-[N-(3,5-difluorophenacetyl)-1-alanyl]-S-phenylglycine-t-butyl-ester was administered in animals of the treatment group. Animals in the control group were given the same amount of solvent. Five days after the surgery, viable flap areas were determined. Skin samples were evaluated for VEGF and Dll4 mRNA levels. Immunohistochemical analysis was used for the assessment of endothelial Dll4 expression. Vascular density was determined histologically. Plasma levels of VEGF and Dll4 were measured.

RESULTS

A significant improvement in TRAM flap surviving area was observed in the treatment group (53.50 ± 14.25%) compared with the controls (32.20 ± 9.15%). Immunohistochemical analysis revealed a significant increase in the number of Dll4 stained vessels in animals of the treatment group (9.2 ± 1.6) in comparison with the controls (5.7 ± 1.9). VEGF mRNA levels (0.22 ± 0.08) in the treatment group were significantly lower than those in the control group (0.36 ± 0.09).

CONCLUSION

Notch inhibition significantly improved TRAM flap survival in animals exposed to nicotine by promoting VEGF-induced angiogenesis.

"Ziziphus jujuba": A red fruit with promising anticancer activities

Ziziphus jujuba Mill. (Z. jujuba) is a traditional herb with a long history of use for nutrition and the treatment of a broad spectrum of diseases. It grows mostly in South and East Asia, as well as in Australia and Europe. Mounting evidence shows the health benefits of Z. jujuba, including anticancer, anti-inflammation, antiobesity, antioxidant, and hepato- and gastrointestinal protective properties, which are due to its bioactive compounds. Chemotherapy, such as with cis-diamminedichloroplatinium (CDDP, cisplatin) and its derivatives, is widely used in cancer treatment. It is an effective treatment for human cancers, including ovarian cancer; however, drug resistance is a major obstacle to successful treatment. A better understanding of the mechanisms and strategies for overcoming chemoresistance can greatly improve therapeutic outcomes for patients. In this review article, the bioactive compounds present in Z. jujuba are explained. The high prevalence of many different cancers worldwide has recently attracted the attention of many researchers. This is why our research group focused on studying the anticancer activity of Z. jujuba as well as its impact on chemoresistance both in vivo and in vitro. We hope that these studies can lead to a promising future for cancer patients.