BET Bromodomain Suppression Inhibits VEGF-induced Angiogenesis and Vascular Permeability by Blocking VEGFR2-mediated Activation of PAK1 and eNOS

Mechanism of Paris polyphylla saponin II inducing autophagic to inhibit angiogenesis of cervical cancer

Paris polyphylla saponin II (PPII) has good biological activity in inhibiting tumor angiogenesis. However, the mechanism of its action is still unclear. This study first observed the inhibitory effect of PPII on cervical cancer cells (Hela) through the establishment of MTT and nude mouse subcutaneous transplantation tumor models. Afterwards, then, we collected Hela cell supernatant for culturing HUVEC cells and treated it with PPII. Observe the invasion, migration, and lumen formation ability of drugs through Transwell, cell scratch test, and angiogenesis experiment. MDC staining was used to observe positive staining in the perinuclear area, AO staining was used to observe acidic areas, and transmission electron microscopy staining was used to observe ultrastructure and autophagy. In addition, the effects of PPII on autophagy- and angiogenesis-related protein expression were detected by Western blotting and quantitative reverse transcriptase polymerase chain reaction. Finally, HUVECs were treated with autophagy inhibitors 3-MA, CQ, and PI3K inhibitor LY294002, respectively. The results showed that the autophagy level of cells treated with PPII was significantly increased. In addition, adding autophagy inhibitors can effectively inhibit angiogenesis in cervical cancer. Further research suggests that PPII induces autophagy in HUVEC cells by regulating the PI3K/AKT/mTOR signaling pathway, thereby affecting angiogenesis and inhibiting Hela cell proliferation, lumen formation, invasion, and migration.

The Pharmacogenetic Variability Associated with the Pharmacokinetics and Pharmacodynamics of Rivaroxaban in Healthy Chinese Subjects: A National Multicenter Exploratory Study

PURPOSE

This study aimed to explore the pharmacogenetic variability associated with the pharmacokinetics (PK) and pharmacodynamics (PD) of rivaroxaban in healthy Chinese subjects.

METHODS

This was a multicenter study that included 304 healthy adults aged 18 to 45 years with unknown genotypes. All participants were administered a single dose of rivaroxaban at 10 mg, 15 mg, or 20 mg. PK and PD parameters were measured, and exome-wide association analysis was conducted.

FINDINGS

Sixteen SNPs located on 11 genes influenced the AUC0-t. Among these, the 3 most influential genes were MiR516A2, PARP14, and MIR618. Thirty-six SNPs from 28 genes were associated with the PD of rivaroxaban. The 3 most influential genes were PKNOX2, BRD3, and APOL4 for anti-Xa activity, and GRIP2, PLCE1, and MLX for diluted prothrombin time (dPT). Among them, BRD3 played an important role in both the PK and PD of rivaroxaban. Anti-Xa activity (ng/mL) differed significantly among subjects with BRD3 rs467387: 145.1 ± 55.5 versus 139.9 ± 65.1 versus 164.0 ± 68.6 for GG, GA, and AA carriers, respectively (P = 0.0002).

IMPLICATIONS

This study found that that the regulation of the BRD3 gene might affect the PK and PD of rivaroxaban, suggesting that it should be studied as a new pharmacologic target. The correlation between this gene locus and clinical outcomes has yet to be verified in patients undergoing clinical treatment.

Oral lipid nanocomplex of BRD4 PROteolysis TArgeting Chimera and vemurafenib for drug-resistant malignant melanoma

BRAF inhibitors (BRAFi) like vemurafenib (VEM) provide initial regression in mutated melanoma but rapidly develop resistance. Molecular pathways responsible for development of resistance against VEM finally converge towards the activation of oncogenic c-Myc. We identified an epigenetic approach to inhibit the c-Myc expression and resensitize BRAFi-resistant melanoma cells. ARV-825 (ARV) was employed as a BRD4 targeted PROteolysis TArgeting Chimera that selectively degrades the BRD4 to downregulate c-Myc. ARV synergistically enhanced the cytotoxicity of VEM in vitro to overcome its resistance in melanoma. Development of ARV and VEM-loaded lipid nanocomplex (NANOVB) significantly improved their physicochemical properties for oral delivery. Most importantly, oral administration of NANOVB substantially inhibited tumor growth at rate of 41.07 mm3/day in nude athymic mice. NANOVB treatment resulted in prolonged survival with 50% of mice surviving until the experimental endpoint. Histopathological analysis revealed significant tumor necrosis and downregulation of Ki-67 and BRD4 protein in vivo. Promising in vivo antitumor activity and prolonged survival demonstrated by NANOVB signifies its clinical translational potential for BRAFi-resistant melanoma.

Impact of Short-Term (+)-JQ1 Exposure on Mouse Aorta: Unanticipated Inhibition of Smooth Muscle Contractility

(+)-JQ1, a specific chemical inhibitor of bromodomain and extraterminal (BET) family protein 4 (BRD4), has been reported to inhibit smooth muscle cell (SMC) proliferation and mouse neointima formation via BRD4 regulation and modulate endothelial nitric oxide synthase (eNOS) activity. This study aimed to investigate the effects of (+)-JQ1 on smooth muscle contractility and the underlying mechanisms. Using wire myography, we discovered that (+)-JQ1 inhibited contractile responses in mouse aortas with or without functional endothelium, reducing myosin light chain 20 (LC20) phosphorylation and relying on extracellular Ca2+. In mouse aortas lacking functional endothelium, BRD4 knockout did not alter the inhibition of contractile responses by (+)-JQ1. In primary cultured SMCs, (+)-JQ1 inhibited Ca2+ influx. In aortas with intact endothelium, (+)-JQ1 inhibition of contractile responses was reversed by NOS inhibition (L-NAME) or guanylyl cyclase inhibition (ODQ) and by blocking the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) pathway. In cultured human umbilical vein endothelial cells (HUVECs), (+)-JQ1 rapidly activated AKT and eNOS, which was reversed by PI3K or ATK inhibition. Intraperitoneal injection of (+)-JQ1 reduced mouse systolic blood pressure, an effect blocked by co-treatment with L-NAME. Interestingly, (+)-JQ1 inhibition of aortic contractility and its activation of eNOS and AKT were mimicked by the (-)-JQ1 enantiomer, which is structurally incapable of inhibiting BET bromodomains. In summary, our data suggest that (+)-JQ1 directly inhibits smooth muscle contractility and indirectly activates the PI3K/AKT/eNOS cascade in endothelial cells; however, these effects appear unrelated to BET inhibition. We conclude that (+)-JQ1 exhibits an off-target effect on vascular contractility.

The BET inhibitor apabetalone decreases neuroendothelial proinflammatory activation in vitro and in a mouse model of systemic inflammation

Brain vascular inflammation is characterized by endothelial activation and immune cell recruitment to the blood vessel wall, potentially causing a breach in the blood - brain barrier, brain parenchyma inflammation, and a decline of cognitive function. The clinical-stage small molecule, apabetalone, reduces circulating vascular endothelial inflammation markers and improves cognitive scores in elderly patients by targeting epigenetic regulators of gene transcription, bromodomain and extraterminal proteins. However, the effect of apabetalone on cytokine-activated brain vascular endothelial cells (BMVECs) is unknown. Here, we show that apabetalone treatment of BMVECs reduces hallmarks of in vitro endothelial activation, including monocyte chemoattractant protein-1 (MCP-1) and RANTES chemokine secretion, cell surface expression of endothelial cell adhesion molecule VCAM-1, as well as endothelial capture of THP-1 monocytes in static and shear stress conditions. Apabetalone pretreatment of THP-1 downregulates cell surface expression of chemokine receptors CCR1, CCR2, and CCR5, and of the VCAM-1 cognate receptor, integrin α4. Consequently, apabetalone reduces THP-1 chemoattraction towards soluble CCR ligands MCP-1 and RANTES, and THP-1 adhesion to activated BMVECs. In a mouse model of brain inflammation, apabetalone counters lipopolysaccharide-induced transcription of endothelial and myeloid cell markers, consistent with decreased neuroendothelial inflammation. In conclusion, apabetalone decreases proinflammatory activation of brain endothelial cells and monocytes in vitro and in the mouse brain during systemic inflammation.

Large-scale genetic screens identify BET-1 as a cytoskeleton regulator promoting actin function and life span

The actin cytoskeleton is a three-dimensional scaffold of proteins that is a regulatory, energyconsuming network with dynamic properties to shape the structure and function of the cell. Proper actin function is required for many cellular pathways, including cell division, autophagy, chaperone function, endocytosis, and exocytosis. Deterioration of these processes manifests during aging and exposure to stress, which is in part due to the breakdown of the actin cytoskeleton. However, the regulatory mechanisms involved in preservation of cytoskeletal form and function are not well-understood. Here, we performed a multipronged, cross-organismal screen combining a whole-genome CRISPR-Cas9 screen in human fibroblasts with in vivo Caenorhabditis elegans synthetic lethality screening. We identified the bromodomain protein, BET-1, as a key regulator of actin function and longevity. Overexpression of bet-1 preserves actin function at late age and promotes life span and healthspan in C. elegans. These beneficial effects are mediated through actin preservation by the transcriptional regulator function of BET-1. Together, our discovery assigns a key role for BET-1 in cytoskeletal health, highlighting regulatory cellular networks promoting cytoskeletal homeostasis.

Palmitoyl Carnitine-Anchored Nanoliposomes for Neovasculature-Specific Delivery of Gemcitabine Elaidate to Treat Pancreatic Cancer

Being the fourth most fatal malignancy worldwide, pancreatic cancer is on track to become the second leading cause of cancer-related deaths in the United States by 2030. Gemcitabine is a first-line chemotherapeutic agent for pancreatic ductal adenocarcinoma (PDAC). Gemcitabine Elaidate (Gem Elaidate) is a lipophilic derivative which allows hENT1-independent intracellular delivery of gemcitabine and better pharmacokinetics and entrapment in a nanocarrier. Cancer cells and neovasculature are negatively charged compared to healthy cells. Palmitoyl-DL-carnitine chloride (PC) is a Protein kinase C (PKC) inhibitor which also provides a cationic surface charge to nanoliposomes for targeting tumor neovasculature and augmented anticancer potency. The objectives of our study are: (a) to develop and characterize a PKC inhibitor-anchored Gem Elaidate-loaded PEGylated nanoliposome (PGPLs) and (b) to investigate the anticancer activity of Gem Elaidate and PGPLs in 2D and 3D models of pancreatic cancer. The optimized PGPLs resulted in a particle size of 80 ± 2.31 nm, a polydispersity index of 0.15 ± 0.05 and a ζ-potential of +31.6 ± 3.54 mV, with a 93.25% encapsulation efficiency of Gem Elaidate in PGPLs. Our results demonstrate higher cellular uptake, inhibition in migration, as well as angiogenesis potential and significant apoptosis induced by PGPLs in 3D multicellular tumor spheroids of pancreatic cancer cells. Hence, PGPLs could be an effective and novel nanoformulation for the neovasculature-specific delivery of Gemcitabine Elaidate to treat PDAC.

Small Molecule BRD4 Inhibitors Apabetalone and JQ1 Rescues Endothelial Cells Dysfunction, Protects Monolayer Integrity and Reduces Midkine Expression

NF-κB signaling is a key regulator of inflammation and atherosclerosis. NF-κB cooperates with bromodomain-containing protein 4 (BRD4), a transcriptional and epigenetic regulator, in endothelial inflammation. This study aimed to investigate whether BRD4 inhibition would prevent the proinflammatory response towards TNF-α in endothelial cells. We used TNF-α treatment of human umbilical cord-derived vascular endothelial cells to create an in vitro inflammatory model system. Two small molecule inhibitors of BRD4—namely, RVX208 (Apabetalone), which is in clinical trials for the treatment of atherosclerosis, and JQ1—were used to analyze the effect of BRD4 inhibition on endothelial inflammation and barrier integrity. BRD4 inhibition reduced the expression of proinflammatory markers such as SELE, VCAM-I, and IL6 in endothelial cells and prevented TNF-α-induced endothelial tight junction hyperpermeability. Endothelial inflammation was associated with increased expression of the heparin-binding growth factor midkine. BRD4 inhibition reduced midkine expression and normalized endothelial permeability upon TNF-α treatment. In conclusion, we identified that TNF-α increased midkine expression and compromised tight junction integrity in endothelial cells, which was preventable by pharmacological BRD4 inhibition.

Virtual ChIP-seq: predicting transcription factor binding by learning from the transcriptome

Existing methods for computational prediction of transcription factor (TF) binding sites evaluate genomic regions with similarity to known TF sequence preferences. Most TF binding sites, however, do not resemble known TF sequence motifs, and many TFs are not sequence-specific. We developed Virtual ChIP-seq, which predicts binding of individual TFs in new cell types, integrating learned associations with gene expression and binding, TF binding sites from other cell types, and chromatin accessibility data in the new cell type. This approach outperforms methods that predict TF binding solely based on sequence preference, predicting binding for 36 TFs (MCC>0.3).

New Druggable Targets for Rheumatoid Arthritis Based on Insights From Synovial Biology

Rheumatoid arthritis (RA) is a multifactorial autoimmune disease characterized by chronic inflammation and destruction of multiple small joints which may lead to systemic complications. Altered immunity via pathogenic autoantibodies pre-date clinical symptom development by several years. Incompletely understood range of mechanisms trigger joint-homing, leading to clinically evident articular disease. Advances in therapeutic approaches and understanding pathogenesis have improved prognosis and likely remission. However, partial/non-response to conventional and biologic therapies witnessed in a subset of patients highlights the need for new therapeutics. It is now evident that joint disease chronicity stems from recalcitrant inflammatory synovial environment, majorly maintained by epigenetically and metabolically reprogrammed synoviocytes. Therefore, interference with effector functions of activated cell types seems a rational strategy to reinstate synovial homeostasis and complement existing anti-inflammatory interventions to mitigate chronic RA. Presenting this newer aspect of fibroblast-like synoviocytes and myeloid cells underlying the altered synovial biology in RA and its potential for identification of new druggable targets is attempted in this review. Major leads from i) molecular insights of pathogenic cell types from hypothesis free OMICS approaches; ii) hierarchy of their dysregulated signaling pathways; and iii) knowledge of druggability of molecular nodes in these pathways are highlighted. Development of such synovial biology-directed therapeutics hold promise for an enriched drug repertoire for RA.

Inhibitory Effect of Punicalagin on Inflammatory and Angiogenic Activation of Human Umbilical Vein Endothelial Cells

Punicalagin, a major ellagitannin isolated from pomegranate, is proved to have various pharmacological activities with an undefined therapy mechanism. The objective of this research was to demonstrate the effect of punicalagin on anti-inflammatory and angiogenic activation in human umbilical vein endothelial cells (HUVECs) and their potential mechanisms. Endothelial-leukocyte adhesion assay was applied to evaluate primary cultures of HUVECs activation following tumor necrosis factor alpha (TNF-α) treatment. The endothelial cell proliferation, migration, permeability and tube formation were assessed by EdU assay, wound migration assay, trans-endothelial electrical resistances (TEER) assay, and capillary-like tube formation assay, respectively. In addition, the expression of relevant proteins was assessed using Western blot analysis. We confirmed that punicalagin could reduce the adhesion of human monocyte cells to HUVECs in vitro and in vivo. Further, punicalagin decreased the expression of mRNA and proteins of ICAM-1 and VCAM-1 in HUVECs. Moreover, punicalagin inhibited permeability, proliferation, migration, and tube formation in VEGF-induced HUVECs, suppressed IKK-mediated activation of NF-κB signaling in TNF-α-induced endothelial cells, and inhibited vascular endothelial growth factor receptor 2 (VEGFR2) activation and downstream p-PAK1. Our findings indicated that punicalagin might have a protective effect on HUVECs activation, which suggested that punicalagin functions through an endothelial mediated mechanism for treating various disorders such as, cancer, rheumatoid arthritis, and cardiovascular disease.

Leonurine Ameliorates Oxidative Stress and Insufficient Angiogenesis by Regulating the PI3K/Akt-eNOS Signaling Pathway in H2O2-Induced HUVECs

Thrombus is considered to be the pathological source of morbidity and mortality of cardiovascular disease and thrombotic complications, while oxidative stress is regarded as an important factor in vascular endothelial injury and thrombus formation. Therefore, antioxidative stress and maintaining the normal function of vascular endothelial cells are greatly significant in regulating vascular tension and maintaining a nonthrombotic environment. Leonurine (LEO) is a unique alkaloid isolated from Leonurus japonicus Houtt (a traditional Chinese medicine (TCM)), which has shown a good effect on promoting blood circulation and removing blood stasis. In this study, we explored the protective effect and action mechanism of LEO on human umbilical vein endothelial cells (HUVECs) after damage by hydrogen peroxide (H₂O₂). The protective effects of LEO on H₂O₂-induced HUVECs were determined by measuring the cell viability, cell migration, tube formation, and oxidative biomarkers. The underlying mechanism of antioxidation of LEO was investigated by RT-qPCR and western blotting. Our results showed that LEO treatment promoted cell viability; remarkably downregulated the intracellular generation of reactive oxygen species (ROS), malondialdehyde (MDA) production, and lactate dehydrogenase (LDH); and upregulated the nitric oxide (NO) and superoxide dismutase (SOD) activity in H₂O₂-induced HUVECs. At the same time, LEO treatment significantly promoted the phosphorylation level of angiogenic protein PI3K, Akt, and eNOS and the expression level of survival factor Bcl2 and decreased the expression level of death factor Bax and caspase3. In conclusion, our findings suggested that LEO can ameliorate the oxidative stress damage and insufficient angiogenesis of HUVECs induced by H₂O₂ through activating the PI3K/Akt-eNOS signaling pathway.

Three-dimensional CRISPR screening reveals epigenetic interaction with anti-angiogenic therapy

Angiogenesis underlies development, physiology and pathogenesis of cancer, eye and cardiovascular diseases. Inhibiting aberrant angiogenesis using anti-angiogenic therapy (AAT) has been successful in the clinical treatment of cancer and eye diseases. However, resistance to AAT inevitably occurs and its molecular basis remains poorly understood. Here, we uncover molecular modifiers of the blood endothelial cell (EC) response to a widely used AAT bevacizumab by performing a pooled genetic screen using three-dimensional microcarrier-based cell culture and CRISPR–Cas9. Functional inhibition of the epigenetic reader BET family of proteins BRD2/3/4 shows unexpected mitigating effects on EC survival and/or proliferation upon VEGFA blockade. Moreover, transcriptomic and pathway analyses reveal an interaction between epigenetic regulation and anti-angiogenesis, which may affect chromosomal structure and activity in ECs via the cell cycle regulator CDC25B phosphatase. Collectively, our findings provide insight into epigenetic regulation of the EC response to VEGFA blockade and may facilitate development of quality biomarkers and strategies for overcoming resistance to AAT.

Through three-dimensional CRISPR screening, He et al. report that functional inhibition of BET family of proteins BRD2/3/4 shows mitigating effects on blood endothelial cell (EC) survival and/or proliferation upon VEGFA blockade. An interaction between epigenetic regulation and anti-angiogenesis, which may affect chromosomal structure and activity in ECs through CDC25B phosphatase, is potentially involved with EC resistance to anti-angiogenic therapy.

Use of Post-transplant Cyclophosphamide Treatment to Build a Tolerance Platform to Prevent Liquid and Solid Organ Allograft Rejection

Corneal transplantation (CT) is the most frequent type of solid organ transplant (SOT) performed worldwide. Unfortunately, immunological rejection is the primary cause of graft failure for CT and therefore advances in immune regulation to induce tolerance remains an unmet medical need. Recently, our work and others in pre-clinical studies found that cyclophosphamide (Cy) administered after (“post-transplant,” PTCy) hematopoietic stem cell transplantation (HSCT), i.e., liquid transplants is effective for graft vs. host disease prophylaxis and enhances overall survival. Importantly, within the past 10 years, PTCy has been widely adopted for clinical HSCT and the results at many centers have been extremely encouraging. The present studies found that Cy can be effectively employed to prolong the survival of SOT, specifically mouse corneal allografts. The results demonstrated that the timing of PTCy administration is critical for these CT and distinct from the kinetics employed following allogeneic HSCT. PTCy was observed to interfere with neovascularization, a process critically associated with immune rejection of corneal tissue that ensues following the loss of ocular “immune privilege.” PTCy has the potential to delete or directly suppress allo-reactive T cells and treatment here was shown to diminish T cell rejection responses. These PTCy doses were observed to spare significant levels of CD4⁺ FoxP3⁺ (Tregs) which were found to be functional and could readily receive stimulating signals leading to their in vivo expansion via TNFRSF25 and CD25 agonists. In total, we posit future studies can take advantage of Cy based platforms to generate combinatorial strategies for long-term tolerance induction.

JAK/STAT and VEGF/PAK1 signaling as emerging targets for topical treatment of psoriasis: a pilot study

Psoriasis is reportedly modulated by the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) or vascular endothelial growth factor/p21-activated kinase 1 (VEGF/PAK1) pathways. However, no research has evaluated the expression of JAK/STAT and VEGF/PAK1 signaling pathway molecules in human psoriasis skin tissue concurrently. We investigated the expression of autocrine STAT1, STAT3, VEGF, suppressor of cytokine signaling-1 (SOCS1), SOCS3, and PAK1 in psoriatic tissues. Skin biopsies were retrospectively collected from 55 patients with psoriasis from the tissue biobank. Skin biopsies from 40 healthy volunteers undergoing plastic surgery were used as controls. Immunohistochemical staining revealed that STAT1, STAT3, SOCS1, SOCS3, VEGF, and PAK1 were present at significantly higher levels in the psoriasis samples compared to the control group. Similarly, the mRNA expression of these signaling molecules was also significantly upregulated in psoriatic skin. Additionally, some of the molecules in these two signaling pathways exhibited significant positive correlations. In summary, we present pilot evidence that JAK/STAT and VEGF/PAK1 signaling molecules are expressed in psoriasis, which may provide topical treatment targets for this disease.

BRD4 and PIN1 gene polymorphisms are associated with high pulse pressure risk in a southeastern Chinese population

Background

BRD4 and PIN1 have been described to be involved in inflammation and vascular endothelial cell dysfunction, which in turn may increase pulse pressure.

Hypothesis

Genetic mutations within the BRD4 and PIN1 genes could affect the risk of high pulse pressure.

Methods

A total of four single nucleotide polymorphisms (SNPs) (BRD4: rs4808278; PIN1: rs2233678, rs2287838, and rs2233682) were genotyped in a cohort of 666 hypertensive patients and 232 normotensive controls with Chinese Han origin. Generalized multifactor dimensionality reduction (GMDR) was used to screen the best interaction combination among the four SNPs within the BRD4 and PIN1 genes and diabetes. Logistic regression analysis was performed to calculate the odds ratio (ORs) (95% confidence interval (CI)) for the association between the four SNPs.

Results

Adjusted for age, weight, waist circumference, drinking, smoking, hypertension, and diabetes, high pulse pressure risk was significantly higher for carriers with the rs4808278-TT genotype in BRD4 than those with wild genotypes (OR: 0.400, 95% CI: 0.217–0.737, P* < 0.05). However, we did not find any significant association of rs2233678, rs2287838, and rs2233682 in PIN1 with high pulse pressure susceptibility after covariate adjustment. GMDR analysis indicated a significant three-locus model (P = 0.0107) involving rs4808278, rs2233678, and diabetes, the cross-validation consistency of the three-locus models was 9/10, and the testing accuracy was 57.47%.

Conclusions

Genetic mutations within BRD4 (rs4808278) could affect the susceptibility to high pulse pressure in a southeastern Chinese population.

Protein kinase C inhibitor anchored BRD4 PROTAC PEGylated nanoliposomes for the treatment of vemurafenib-resistant melanoma

Limited treatment options and development of resistance to targeted therapy within few months pose significant challenges in the treatment of BRAF-mutated malignant melanoma. Moreover, extensive angiogenesis and vasculogenic mimicry promote the rapid progression of disease. The purpose of this study was to develop a protein kinase C inhibitor anchored BRD4 PROTAC (ARV) loaded PEGylated nanoliposomes (LARPC). Palmitoyl-dl-carnitine chloride (PC) was used as a protein kinase C inhibitor to provide a cationic surface charge to LARPC. The formulation was characterized for particle size, zeta potential, drug release and various cell culture assays using HUVEC and vemurafenib resistant melanoma cells. The particle size of LARPC was found to be 105.25 ± 2.76 nm with a zeta potential of +26.6 ± 6.25 mV. Inhibition of angiogenesis was demonstrated by ARV and LARPC using human umbilical vein endothelial cells (HUVEC)-based matrigel basement membrane model. Additionally, LARPC demonstrated very low IC50 with promising inhibition of vasculogenic mimicry channel formation, cell migration as well as colony formation in vemurafenib-resistant melanoma cell lines. Hence, the outcome of this combination therapy indicated the suitability of LARPC as a potential and novel approach for eradicating vemurafenib-resistant melanoma.

Evaluation of BRD4 levels in patients with early-onset preeclampsia

OBJECTIVE

This study aimed to detect Bromodomain Containing Protein 4 (BRD4) concentrations in the serum of early-onset preeclamptic patients and compare them with the healthy control group.

MATERIAL AND METHODS

This prospective case-control study was performed from June 2019 to December 2019. Of the 80 pregnant patients included in the study, we enrolled 40 patients with early-onset preeclampsia as the study group, and 40 normotensive healthy gestational age- and gravidity-matched patients with normal blood pressure without proteinuria as the control group. Demographic characteristics, amount of proteinuria, and serum BRD4 concentrations were recorded.

RESULTS

Maternal serum BRD4 concentrations were significantly higher in patients with preeclampsia (39.10 ± 42.14 ng/mL) compared to the participants in the control group (13.64 ± 7.24 ng/mL, p < 0.001). There was a positive intermediate correlation between serum BRD4 levels and the amount of proteinuria (r = 0.447, p = 0.006).

CONCLUSION

Maternal serum BRD4 levels were significantly higher in preeclamptic patients compared to healthy pregnant women. Also, the amount of proteinuria was positively correlated with serum BRD4 levels. Although this preliminary study shows increased BRD4 levels in preeclampsia, its utility as a biomarker must be clarified.

A Bromodomain-Containing Protein 4 (BRD4) Inhibitor Suppresses Angiogenesis by Regulating AP-1 Expression

Angiogenesis dysregulation contributes to inflammation, infections, immune disorders, and carcinogenesis. Bromodomain-containing protein 4 (BRD4) is an epigenetic reader that recognizes histone proteins and acts as a transcriptional regulator to trigger tumor growth and the inflammatory response. The pan-bromodomain and extra-terminal domain (BET) inhibitor, (+)-JQ1 (1), was reported to inhibit angiogenesis. However, owing to the non-selectivity action of (+)-JQ1 towards all BET family members, the role of BRD4 and that of its bromodomains (BD1 and BD2) in angiogenesis remains elusive. Herein, we identified a potent BRD4 inhibitor, ZL0513 (7), which exhibited significant anti-angiogenic effects in chick embryo chorioallantoic membrane (CAM) and yolk sac membrane (YSM) models. This inhibitor also directly suppressed the viability and tube formation of human umbilical vascular endothelial cells (HUVECs). Moreover, ZL0513 (7) was found to inhibit the phosphorylation of c-jun and c-fos, important members of activating protein-1 (AP-1) transcription factor complexes that enhance angiogenesis. The findings on this novel BRD4 inhibitor indicate that, in addition to being a powerful pharmacological tool for further elucidating the roles and functions of BRD4 and its BD domains in angiogenesis, it may serve as a potential therapeutic strategy for targeting the vasculature in various angiogenesis-dysregulated human diseases.

The Impact of obesity and diabetes mellitus on pancreatic cancer: Molecular mechanisms and clinical perspectives

The incidence of obesity and type 2 diabetes (T2DM) in the Western world has increased dramatically during the recent decades. According to the American Cancer Society, pancreatic cancer (PC) is the fourth leading cause of cancer‐related death in the United States. The relationship among obesity, T2DM and PC is complex. Due to increase in obesity, diabetes, alcohol consumption and sedentary lifestyle, the mortality due to PC is expected to rise significantly by year 2040. The underlying mechanisms by which diabetes and obesity contribute to pancreatic tumorigenesis are not well understood. Furthermore, metabolism and microenvironment within the pancreas can also modulate pancreatic carcinogenesis. The risk of PC on a population level may be reduced by modifiable lifestyle risk factors. In this review, the interactions of diabetes and obesity to PC development were summarized, and novel strategies for the prevention and treatment of diabetes and PC were discussed.

The therapeutic potential of BRD4 in cardiovascular disease

Bromodomain-containing protein 4 (BRD4) is a member of the bromodomain and extra terminal (BET) protein family that has gained wide attention in the field of cancer due to its role in the formation of super enhancers (SEs) and the regulation of oncogene expression. However, there is increasing evidence that BRD4 also plays a pivotal role in a variety of cardiovascular diseases, suggesting that understanding the mechanisms of BRD4 in these diseases is important to advance studies and clinical treatment. In this article, we summarize the mechanisms of BRD4 in cardiovascular diseases, including pulmonary arterial hypertension, heart failure, atherosclerosis, and hypertension. In addition, we discuss small molecule inhibitors of BRD4 as novel therapeutic strategies for cardiovascular diseases.

Non-invasive measurement of retinal permeability in a diabetic rat model

OBJECTIVE

The gold standard for measuring blood-retinal barrier permeability is the Evans blue assay. However, this technique has limitations in vivo, including non-specific tissue binding and toxicity. This study describes a non-toxic, high-throughput, and cost-effective alternative technique that minimizes animal usage.

METHODS

Sodium fluorescein fundus angiography was performed in non-diabetic and diabetic Brown Norway rats on days 0, 7, 14, 21, and 28. Sodium fluorescein intensity in the retinal interstitium and a main retinal vessel were measured over time. The intensity gradients were used to quantify retinal vascular permeability. Post-study eyes were fixed, dissected, and stained (isolectin B4) to measure required parameters for permeability quantification including total vessel length per retinal volume, radius, and thickness.

RESULTS

In the non-diabetic cohort retinal permeability remained constant over the 28-day study period. However, in the diabetic cohort there was a significant and progressive increase in retinal permeability from days 14-28 (P < .01, P < .001, P < .0001).

CONCLUSIONS

This novel imaging methodology in combination with mathematical quantification allows retinal permeability to be non-invasively and accurately measured at multiple time points in the same animal. In addition, this technique is a non-toxic, rapid, sensitive, and cost-effective alternative to the Evans blue assay.

BET Epigenetic Reader Proteins in Cardiovascular Transcriptional Programs

Epigenetic mechanisms involve the placing (writing) or removal (erasing) of histone modifications that allow heterochromatin to transition to the open, activated euchromatin state necessary for transcription. A third, less studied epigenetic pathway involves the reading of these specific histone marks once placed. The BETs (bromodomain and extraterminal-containing protein family), which includes BRD2, BRD3, and BRD4 and the testis-restricted BRDT, are epigenetic reader proteins that bind to specific acetylated lysine residues on histone tails where they facilitate the assembly of transcription complexes including transcription factors and transcriptional machinery like RNA Polymerase II. As reviewed here, considerable recent data establishes BETs as novel determinants of induced transcriptional programs in vascular cells, like endothelial cells and vascular smooth muscle cells, cardiac myocytes and inflammatory cells, like monocyte/macrophages, cellular settings where these epigenetic reader proteins couple proximal stimuli to chromatin, acting at super-enhancer regulatory regions to direct gene expression. BET inhibition, including the use of specific chemical BET inhibitors like JQ-1, has many reported effects in vivo in the cardiovascular setting, like decreasing atherosclerosis, angiogenesis, intimal hyperplasia, pulmonary arterial hypertension, and cardiac hypertrophy. At the same time, data in endothelial cells, adipocytes, and elsewhere suggest BETs also help regulate gene expression under basal conditions. Studies in the cardiovascular setting have highlighted BET action as a means of controlling gene expression in differentiation, cell identity, and cell state transitions, whether physiological or pathological, adaptive, or maladaptive. While distinct BET inhibitors are being pursued as therapies in oncology, a large prospective clinical cardiovascular outcome study investigating the BET inhibitor RVX-208 (now called apabetalone) has already been completed. Independent of this specific agent and this one trial or the numerous unanswered questions that remain, BETs have emerged as novel epigenetic players involved in the execution of coordinated transcriptional programs in cardiovascular health and disease.

Purpuric drug eruptions induced by EGFR tyrosine kinase inhibitors are associated with IQGAP1-mediated increase in vascular permeability

Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) are used as a treatment for non-small-cell lung cancer. There have been some reports of EGFR-TKIs being associated with vascular adverse events. We found that EGFR-TKIs decreased the proliferation of HMEC-1s (immortalized human dermal microvascular endothelial cells) and HMVECs (human dermal microvascular endothelial cells), and also inhibited the phosphorylation of EGFR and ERK. We examined the mRNA expression profile of erlotinib-treated HMEC-1s and identified IQ motif containing GTPase activating protein 1 (IQGAP1) as the most consistently up-regulated transcript and protein. IQGAP1 was also overexpressed and co-localized with endothelial cells in the lesional skin. Notably, increased IQGAP1 expression was associated with decreased transendothelial electrical resistance and increased vascular permeability in vitro. Erlotinib treatment enriched the staining of IQGAP1 and reduced the intensities of α-catenin at the sites of cell-cell contact. In conclusion, erlotinib induces adherens junction dysfunction by modulating the expression of IQGAP1 in dermal endothelial cells. © 2020 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Vascular endothelial growth factor regulation of endothelial nitric oxide synthase phosphorylation is involved in isoflurane cardiac preconditioning

Aims

Previous studies indicate that nitric oxide derived from endothelial nitric oxide synthase (eNOS) serves as both trigger and mediator in anaesthetic cardiac preconditioning. The mechanisms underlying regulation of eNOS by volatile anaesthetics have not been fully understood. Therefore, this study examined the role of vascular endothelial growth factor (VEGF) in isoflurane cardiac preconditioning.

Methods and results

Wistar rats underwent 30 min of coronary artery occlusion followed by 2 h of reperfusion. Isoflurane given prior to ischaemia/reperfusion significantly decreased myocardial infarct size from 60 ± 1% in control to 40 ± 3% (n = 8 rats/group, P < 0.05). The beneficial effects of isoflurane were blocked by neutralizing antibody against VEGF (nVEGF). Coronary arterial endothelial cells (ECs) alone or together with cardiomyocytes (CMs) were subjected to hypoxia/reoxygenation injury. The expression of VEGF and eNOS was analysed by western blot, and nitric oxide was measured by ozone-based chemiluminescence. In co-cultured CMs and ECs, isoflurane administered before hypoxia/reoxygenation attenuated lactate dehydrogenase activity and increased the ratio of phosphorylated eNOS/eNOS and nitric oxide production. The protective effect of isoflurane on CMs was compromised by nVEGF and after VEGF in ECs was inhibited with hypoxia inducible factor-1α short hairpin RNA (shRNA). The negative effect of hypoxia inducible factor-1α shRNA was restored by recombinant VEGF.

Conclusion

Isoflurane cardiac preconditioning is associated with VEGF regulation of phosphorylation of eNOS and nitric oxide production.

JQ1 inhibits tumour growth in combination with cisplatin and suppresses JAK/STAT signalling pathway in ovarian cancer

BACKGROUND

Overexpression of c-Myc is commonly seen in human ovarian cancers, and this could be a potentially novel therapeutic target for this disease. JQ1, a selective small-molecule BET (Bromodomain and extraterminal domain family) bromodomain (BRDs) inhibitor, has been found to suppress tumour progression in several cancer cell types.

RESULTS

Using a panel of ovarian cancer cell lines and primary cell cultures from human ovarian cancer ascites, we demonstrated that JQ1 significantly suppressed cell proliferation and induced apoptosis in an ovarian cancer cell by targeting BRD4 and c-Μyc. In addition, JQ1 sensitized ovarian cancer cells to cisplatin, the most commonly used chemotherapeutic agent in ovarian cancer. Importantly, this effect was observed in ovarian cells, which exhibited resistance to cisplatin alone. Finally, we show that JQ1 interacts with the JAK-STAT signalling pathway, a pathway important in supporting ovarian cancer cell survival by suppressing or inducing genes involved in cell survival and apoptosis, respectively.

CONCLUSION

Our data, taken together, suggest that JQ1 is an attractive antitumour candidate for further investigation in the treatment of ovarian cancer, as it associates with cell proliferation, apoptosis, and alterations in the JAK-STAT signalling pathway, especially in patients with a platinum-resistant profile or in patients with relapsed disease.

Triptolide inhibits angiogenesis in microvascular endothelial cells through regulation of miR-92a

Atherosclerosis is one common chronic inflammatory disease in which angiogenesis is involved. Here we established an in vitro cell model of angiogenesis made by human dermal microvascular endothelial cells (HMEC-1) and work to investigate the role of triptolide (TPL) in this model. To induce angiogenesis, HMEC-1 cells were cultured in Matrigel-conditioned medium. The ratio of tubes to nucleus was detected. To evaluate angiogenesis, Western blot assay was carried out to detect endothelial nitric oxide synthase (eNOS), vascular endothelial growth factor receptor-2 (VEGFR2) and VEGF. Cell counting kit-8 was utilized to estimate the viability of HMEC-1 cells. microRNA (miR)-92a was analyzed by qRT-PCR. The targeting relationship between integrin subunit alpha 5 (ITGA5) and miR-92a was verified through luciferase activity assay. The effects of ITGA5 on signaling transducers (ERK, PI3K, and AKT) in a phosphorylated form were valued using Western blot method. After stimulated by TPL, LY294002 and PD98059, the alteration in phosphorylation of the signaling transducers was evaluated by Western blot assay. The ratio of tubes to nucleus and angiogenesis related factors were increased with the delaying of culture time. TPL decreased the expression of angiogenesis factors. Furthermore, miR-92a was upregulated by TPL and miR-92a silence upregulated angiogenesis factors. In addition, TPL decreased ITGA5 which was proved as a target of miR-92a. ITGA5 overexpression resulted in the abundance of angiogenesis factors while ITGA5 silence led to the opposite results. Meanwhile, ITGA5 overexpression increased phosphorylation of ERK, PI3K and AKT while ITGA5 silence reversed the trend. TPL (as an anti-angiogenesis agent) suppressed angiogenesis by upregulating miR-92a, and miR-92a-mediated down-regulation of ITGA5 blocked the signaling transduction of ERK and PI3K/AKT pathways.

Risk stratification for lung adenocarcinoma on EGFR and TP53 mutation status, chemotherapy, and PD-L1 immunotherapy

The overall survival rates for lung cancer remain unsatisfactorily low, even for patients with biomarkers for which target therapies or immunotherapies are recommended. Better identification of at‐risk patients is needed to achieve more effective personalized treatment. Here, we derived a risk‐stratifying gene signature consisting of five genes that had the greatest differential expression by stage from lung adenocarcinoma (LUAD) transcriptomes. The new gene signature enabled survival prognosis for multiple LUAD datasets from different platforms of transcriptomics and risk stratification for patients with and without a mutation in TP53 or EGFR, with high and low levels of PD‐L1, and with and without adjuvant chemotherapy treatment. Using these evaluations, it was also shown to be more robust compared to several other gene signatures. Functional analysis of the five genes and their protein‐protein interaction partners indicated that they are functionally enriched in cell cycle, endocytosis, and EGFR regulation, which are biological processes associated with lung cancer and drug resistance. Extensive discussions on related experimental studies suggest that the five genes are novel and sensible targets for developing new drugs and/or tackling drug resistance problems for LUAD.

Potent anti-cancer activity of Alnus nitida against lung cancer cells; in vitro and in vivo studies

Alnus nitida is used for multiple disorders in norther areas of Pakistan. In this study we have evaluated methanol extract of leaf (ANL) and stem bark (ANB) of A. nitida against two lung cancer cell lines; A-549 and H460 (Human non-small lung cancer cell lines) during in vitro assays for growth inhibition. Treatment with ANL and ANB markedly inhibited the growth of both cancer cell lines. Exposure of A-549 and H460 cancer cell lines to ANL and ANB inhibited cell survival, colony growth and migration of cells. Further, treatment of A-549 and H460 with ANL and ANB indicated alteration in actin fibers after staining with rhodamine-phalloidin. Both extracts cause shrinkage and cell cycle arrest during G1 phase. Treatment of A-549 and H460 cancer cells with ANL and ANB repressed the expression of anti-apoptotic proteins Bcl-2 and Bcl-xL along with downregulation of NFκB, cyclin D1 and PI3-K protein. In addition, intraperitoneal injection of ANL and ANB (10 mg/kg bw and 20 mg/kg bw) to C57BL/6 J mice implanted with B16F10 (Mouse melanoma cancer cell line) cells significantly (p < 0.01) decreased the number of nodules per lung and the level of various proteins reciprocating the in vitro studies. These results suggest that ANL and ANB be explored further for therapeutic use in lung cancer.

Bromodomain protein inhibition: a novel therapeutic strategy in rheumatic diseases

The reading of acetylation marks on histones by bromodomain (BRD) proteins is a key event in transcriptional activation. Small molecule inhibitors targeting bromodomain and extra-terminal (BET) proteins compete for binding to acetylated histones. They have strong anti-inflammatory properties and exhibit encouraging effects in different cell types in vitro and in animal models resembling rheumatic diseases in vivo. Furthermore, recent studies that focus on BRD proteins beyond BET family members are discussed.

A paradigm of endothelium-protective and stent-free anti-restenotic therapy using biomimetic nanoclusters

Drug-eluting stents are the most commonly employed method to control post-angioplasty restenosis. Unfortunately, they exacerbate life-threatening stent thrombosis because of endothelium damage caused by both drug and stenting. To solve this major medical problem, an endothelium-protective and stent-free anti-restenotic method is highly desirable. Here we have generated a biomimetic intravenous delivery system using dendritic polymer-based nanoclusters, which were coated with platelet membranes for targeting to the injured arterial wall where restenosis occurs. These nanoclusters were loaded with an endothelium-protective epigenetic inhibitor (JQ1) or an endothelium-toxic status quo drug (rapamycin), and compared for their ability to mitigate restenosis without hindering the process of re-endothelialization. Fluorescence imaging of Cy5-tagged biomimetic nanoclusters indicated their robust homing to injured, but not uninjured arteries. Two weeks after angioplasty, compared to no-drug control, both rapamycin- and JQ1-loaded biomimetic nanoclusters substantially reduced (by >60%) neointimal hyperplasia, the primary cause of restenosis. However, whereas the rapamycin formulation impaired the endothelial re-coverage of the denuded inner arterial wall, the JQ1 formulation preserved endothelial recovery. In summary, we have created an endothelium-protective anti-restenotic system with biomimetic nanoclusters containing an epigenetic inhibitor. This system warrants further development for a non-thrombogenic and stent-free method for clinical applications.

Bromodomain protein BRD4 is increased in human placentas from women with early-onset preeclampsia

Preeclampsia affects 5% of all pregnancies and is a serious disorder of pregnancy, characterised by high maternal blood pressure, placental hypoxia, fluid retention (oedema) and proteinuria. Women with preeclampsia are associated with exaggerated levels of pro-inflammatory cytokines, chemokines and anti-angiogenic factors such as soluble fms-like tyrosine kinase-1 (sFLT1). Studies in non-gestational tissues have described the bromodomain (BRD) and extraterminal family of proteins, in particular BRD4 to play a critical role in propagating inflammation and is currently a therapeutic target for treating cancer, lung inflammation and asthma. The aims of this study were to: (i) determine the effect of severe early-onset preeclampsia on placental BRD4 expression; (ii) the effect of loss of BRD4 function by siRNA-targeted knockdown or with the BRD inhibitor JQ1 in human primary trophoblast cells and human umbilical vein endothelial cells (HUVECs) on TNF-stimulated production of pro-inflammatory mediators, cell adhesion molecules and anti-angiogenic markers and (iii) the effect of BRD4 suppression on placental sFLT1 secretion under hypoxia conditions and in preeclampic placenta. BRD4 mRNA expression was significantly increased (sevenfold) in severe early-onset preeclampsia placenta. BRD4 silencing resulted in a significant reduction in TNF-induced IL6, CXCL8, CCL2, CXCL1 and sFLT1-e15a mRNA expression and IL6, CXCL8, CCL2, CXCL1 and sFLT1 secretion in primary trophoblast and HUVECs. Additionally, JQ1 treatment significantly reduced placental sFLT1 secretion under hypoxic conditions and in preterm preeclamptic placenta. In conclusion, these findings suggest BRD4 may play a central role in propagating inflammation and endothelial dysfunction associated with the pathophysiology of early-onset preeclampsia.

Prevascularization of natural nanofibrous extracellular matrix for engineering completely biological three-dimensional prevascularized tissues for diverse applications

Self-sustainability after implantation is one of the critical obstacles facing large engineered tissues. A preformed functional vascular network provides an effective solution for solving the mass transportation problem. With the support of mural cells, endothelial cells (ECs) can form microvessels within engineered tissues. As an important mural cell, human mesenchymal stem cells (hMSCs) not only stabilize the engineered microvessel network, but also preserve their multi-potency when grown under optimal culture conditions. A prevascularized hMSC/extracellular matrix (ECM) sheet fabricated by the combination of hMSCs, ECs and a naturally derived nanofibrous ECM scaffold offers great opportunity for engineering mechanically strong and completely biological three-dimensional prevascularized tissues. The objective of this study was to create a prevascularized hMSC/ECM sheet by co-culturing ECs and hMSCs on a nanofibrous ECM scaffold. Physiologically low oxygen (2% O2 ) was introduced during the 7 day hMSC culture to preserve the stemness of hMSCs and thereby their capability to secrete angiogenic factors. The ECs were then included to form microvessels under normal oxygen (20% O2 ) for up to 7 days. The results showed that a branched and mature vascular network was formed in the co-culture condition. Angiogenic factors vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF) and angiopoietin-1 (Ang-1) were significantly increased by low-oxygen culture of hMSCs, which further stabilized and supported the maturation of microvessels. A differentiation assay of the prevascularized ECM scaffold demonstrated a retained hMSC multi-potency in the hypoxia cultured samples. The prevascularized hMSC/ECM sheet holds great promise for engineering three-dimensional prevascularized tissues for diverse applications.

Ponatinib exerts anti-angiogenic effects in the zebrafish and human umbilical vein endothelial cells via blocking VEGFR signaling pathway

Angiogenesis is a hallmark for cancer development because it is essential for cancer growth and provides the route for cancer cell migration (metastasis). Understanding the mechanism of angiogenesis and developing drugs that target the process has therefore been a major focus for research on cancer therapy. In this study, we screened 114 FDA-approved anti-cancer drugs for their effects on angiogenesis in the zebrafish. Among those with positive effects, we chose to focus on Ponatinib (AP24534; Iclusig^®) for further investigation. Ponatinib is an inhibitor of the tyrosine kinase BCR-ABL in chronic myeloid leukemia (CML), and its clinical trial has been approved by FDA for the treatment of the disease. In recent clinical trials, however, some side effects have been reported for Ponatinib, mostly on blood vessel disorders, raising the possibility that this drug may influence angiogenesis. In this study, we demonstrated that Ponatinib was able to suppress the formation of intersegmental vessels (ISV) and subintestinal vessels (SIV) in the zebrafish larvae. The anti-angiogenic effect of Ponatinib was further validated by other bioassays in human umbilical vein endothelial cells (HUVECs), including cell proliferation and migration, tube formation, and wound healing. Further experiments showed that Ponatinib inhibited VEGF-induced VEGFR2 phosphorylation and its downstream signaling pathways including Akt/eNOS/NO pathway and MAPK pathways (ERK and p38MAPK). Taken together, these results suggest that inhibition of VEGF signaling at its receptor level and downstream pathways may likely be responsible for the antiangiogenic activity of Ponatinib.

Preclinical Characterization of BET Family Bromodomain Inhibitor ABBV-075 Suggests Combination Therapeutic Strategies

ABBV-075 is a potent and selective BET family bromodomain inhibitor that recently entered phase I clinical trials. Comprehensive preclinical characterization of ABBV-075 demonstrated broad activity across cell lines and tumor models, representing a variety of hematologic malignancies and solid tumor indications. In most cancer cell lines derived from solid tumors, ABBV-075 triggers prominent G₁ cell-cycle arrest without extensive apoptosis. In this study, we show that ABBV-075 efficiently triggers apoptosis in acute myeloid leukemia (AML), non-Hodgkin lymphoma, and multiple myeloma cells. Apoptosis induced by ABBV-075 was mediated in part by modulation of the intrinsic apoptotic pathway, exhibiting synergy with the BCL-2 inhibitor venetoclax in preclinical models of AML. In germinal center diffuse large B-cell lymphoma, BCL-2 levels or venetoclax sensitivity predicted the apoptotic response to ABBV-075 treatment. In vivo combination studies uncovered surprising benefits of low doses of ABBV-075 coupled with bortezomib and azacitidine treatment, despite the lack of in vitro synergy between ABBV-075 and these agents. The in vitro/in vivo activities of ABBV-075 described here may serve as a useful reference to guide the development of ABBV-075 and other BET family inhibitors for cancer therapy. Cancer Res; 77(11); 2976-89. ©2017 AACR.

Epigenetic intervention with a BET inhibitor ameliorates acute retinal ganglion cell death in mice

PURPOSE

The bromo and extraterminal (BET) epigenetic "reader" family is becoming an appealing new therapeutic target for several common diseases, yet little is known of its role in retinal neurodegeneration. We explored the potential of BET inhibition in the protection of retinal ganglion cells (RGCs).

METHODS

To test the therapeutic effect of JQ1, an inhibitor highly selective for the BET family of proteins, we used an acute RGC damage model induced by N-methyl-D-aspartic acid (NMDA) excitotoxicity. Adult C57BL/6 mice received an intravitreal injection of NMDA with (or without) JQ1 in one eye and vehicle control in the contralateral eye; RGC loss was assessed on retinal sections and whole mounts. Gene expression and apoptosis were analyzed by quantitative real time (RT)-PCR and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL), respectively. For counting RGCs, immunostaining of the marker protein BRN3A was performed on whole mounts.

RESULTS

NMDA treatment eliminated RGCs (day 7 and day 14 post injection) and diminished the expression (mRNAs) of RGC-selective genes, including Thy1, Nrn1, Sncg, and Nfl (day 3 and day 7). In contrast, co-injection with JQ1 maintained the number and gene expression of RGCs at ~2 fold of the control (NMDA only, no JQ1), and it decreased NMDA-induced TUNEL-positive cells in the RGC layer by 35%. While NMDA treatment dramatically upregulated mRNAs of inflammatory cytokines (TNFα, IL-1β, MCP-1, RANTES) in retinal homogenates, co-injection with JQ1 suppressed their upregulation by ~50%.

CONCLUSIONS

Intravitreal injection of a BET inhibitor (JQ1) ameliorates NMDA-induced RGC death, revealing the RGC-protective potential of pharmacological blockage of the BET family. This new strategy of epigenetic intervention may be extended to other retinal degenerative conditions.

Photoreceptor protection via blockade of BET epigenetic readers in a murine model of inherited retinal degeneration

BACKGROUND

The bromodomain and extraterminal domain (BET) family proteins (BET2, BET3, and BET4) "read" (bind) histone acetylation marks via two distinct bromodomains (Brom1 and Brom2) facilitating transcriptional activation. These epigenetic "readers" play crucial roles in pathogenic processes such as inflammation. The role of BETs in influencing the degenerative process in the retina is however unknown.

METHODS

We employed the rd10 mouse model (Pde6b ^rd10 mutation) of retinitis pigmentosa (RP) to examine the involvement of BET proteins in retinal neurodegeneration.

RESULTS

Inhibition of BET activity by intravitreal delivery of JQ1, a BET-specific inhibitor binding both Brom1 and Brom2, ameliorated photoreceptor degeneration and improved electroretinographic function. Rescue effects of JQ1 were related to the suppression of retinal microglial activation in vivo, as determined by decreased immunostaining of activation markers (IBA1, CD68, TSPO) and messenger RNA (mRNA) levels of inflammatory cytokines in microglia purified from rd10 retinas. JQ1 pre-treatment also suppressed microglial activation in vitro, decreasing microglial proliferation, migration, and mRNA expression of inflammatory cytokines (TNFα, MCP-1, IL-1β, IL-6, and RANTES). Expression of BET2, but not BET3 and BET4, was significantly elevated during photoreceptor degeneration at postnatal day (PN)24 in retinas of rd10 mice relative to age-matched wild-type controls. siRNA knockdown of BET2 but not BET4, and the inhibitor of Brom2 (RVX208) but not of Brom1 (Olinone), decreased microglial activation.

CONCLUSIONS

These findings indicate that BET inhibition rescues photoreceptor degeneration likely via the suppression of microglial activation and implicates BET interference as a potential therapeutic strategy for the treatment of degenerative retinal diseases.

Bromodomains in Protozoan Parasites: Evolution, Function, and Opportunities for Drug Development

Parasitic infections remain one of the most pressing global health concerns of our day, affecting billions of people and producing unsustainable economic burdens. The rise of drug-resistant parasites has created an urgent need to study their biology in hopes of uncovering new potential drug targets. It has been established that disrupting gene expression by interfering with lysine acetylation is detrimental to survival of apicomplexan (Toxoplasma gondii and Plasmodium spp.) and kinetoplastid (Leishmania spp. and Trypanosoma spp.) parasites. As "readers" of lysine acetylation, bromodomain proteins have emerged as key gene expression regulators and a promising new class of drug target. Here we review recent studies that demonstrate the essential roles played by bromodomain-containing proteins in parasite viability, invasion, and stage switching and present work showing the efficacy of bromodomain inhibitors as novel antiparasitic agents. In addition, we performed a phylogenetic analysis of bromodomain proteins in representative pathogens, some of which possess unique features that may be specific to parasite processes and useful in future drug development.

The suppression of bromodomain and extra-terminal domain inhibits vascular inflammation by blocking NF-κB and MAPK activation

BACKGROUND AND PURPOSE

There is increasing evidence indicating that bromodomain and extra-terminal domain (BET) proteins play a critical role in the regulation of immune and inflammatory responses; however, their contribution to vascular inflammation has not yet been elucidated. In this study, we investigated the effect of inhibiting BET bromodomain on vascular inflammation and the underlying mechanisms.

EXPERIMENTAL APPROACH

HUVECs were isolated from fresh umbilical cords. JQ1, a specific BET bromodomain inhibitor, and Brd shRNA were used to evaluate the regulation of the BET proteins in vascular inflammation. Leukocyte adhesion to HUVECs was measure by an adhesion assay. Western blot or immunohistochemical analysis was used to detect the protein expression. Real-time PCR was used to evaluate mRNA expression. Leukocyte accumulation in vivo was determined by an acute lung inflammation model.

KEY RESULTS

BET bromodomain inhibition suppressed the expression of adhesion molecules induced by TNF-α- or LPS, including ICAM-1, VCAM-1 and E-selectin, and inhibited leukocyte adhesion to activated HUVEC monolayers. Treatment with JQ1 also attenuated the LPS-induced accumulation of leukocytes and expression of endothelial adhesion molecules in the acute lung inflammation model in vivo. Furthermore, BET bromodomain inhibition reduced the activity of p38 and JNK MAPKs and NF-κB in TNF-α-stimulated HUVECs. TNF-α-induced NF-κB activation was also blocked by inhibitors of p38 (SB203580) or JNK (SP600125).

CONCLUSIONS AND IMPLICATIONS

BET bromodomain is important for regulating endothelial inflammation. Strategies targeting endothelial BET bromodomain may provide a new therapeutic approach for controlling inflammatory-related diseases.

Bromodomain and Extra-terminal (BET) Protein Inhibitors Suppress Chondrocyte Differentiation and Restrain Bone Growth

Small molecule inhibitors for bromodomain and extra-terminal (BET) proteins have recently emerged as potential therapeutic agents in clinical trials for various cancers. However, to date, it is unknown whether these inhibitors have side effects on bone structures. Here, we report that inhibition of BET bromodomain proteins may suppress chondrocyte differentiation and restrain bone growth. We generated a luciferase reporter system using the chondrogenic cell line ATDC5 in which the luciferase gene was driven by the promoter of Col2a1, an elementary collagen of the chondrocyte. The Col2a1-luciferase ATDC5 system was used for rapidly screening both activators and repressors of human collagen Col2a1 gene expression, and we found that BET bromodomain inhibitors reduce the Col2a1-luciferase. Consistent with the luciferase assay, BET inhibitors decrease the expression of Col2a1 Furthermore, we constructed a zebrafish line in which the enhanced green fluorescent protein (EGFP) expression was driven by col2a1 promoter. The transgenic (col2a1-EGFP) zebrafish line demonstrated that BET inhibitors I-BET151 and (+)-JQ1 may affect EGFP expression in zebrafish. Furthermore, we found that I-BET151 and (+)-JQ1 may affect chondrocyte differentiation in vitro and inhibit zebrafish growth in vivo Mechanistic analysis revealed that BET inhibitors influenced the depletion of RNA polymerase II from the Col2a1 promoter. Collectively, these results suggest that BET bromodomain inhibition may have side effects on skeletal bone structures.