Circulating adropin and vascular endothelial growth factor receptor-2 levels in age-related macular degeneration and T2DM patients-A cross-sectional study

Background:

Macular drusen formation and angiogenesis are the two chief processes associated with age-related macular degeneration. Adropin and vascular endothelial growth factor receptor-2 (VEGFR-2) may be involved in these pathologies. By altering lipid metabolism, adropin may contribute in the early stages of age-related macular degeneration (AMD). VEGFR-2 may participate in the later form of AMD, by promoting angiogenesis. This study compared the circulatory levels of adropin and VEGFR-2 in AMD and patients without AMD and assessed their association with disease severity, to understand their possible role in AMD.

Objectives:

This study aimed to assess and compare the serum levels of adropin and VEGFR-2 in patients with AMD and type 2 diabetes patients without AMD, and, to investigate the correlation between these two parameters with disease severity.

Methods:

Our study involves two groups of 39 each. Group A (age-related macular degeneration) and Group B (diabetes patients without age-related macular degeneration). Routine parameters fasting blood sugar (FBS), lipid profile, and liver function tests (LFT) were estimated by using autoanalyzer. Serum adropin and VEGFR-2 were assessed by ELISA.

Results:

Among the basic parameters, systolic blood pressure and fasting blood glucose alone were significantly different across the groups. We did not find significant alterations in adropin and VEGFR-2 levels between the study groups. Our lipid profile parameters (triglycerides and total cholesterol) have significant positive association. VEGFR-2 showed a positive correlation with the severity of AMD. Adropin did not exhibit any correlation with disease severity and with VEGFR-2.

Conclusion:

We could not find any observable alterations of statistical significance, in adropin and VEGFR-2 levels. VEGFR-2's correlation with disease severity could be important. Adropin might have subtler roles in AMD, though not evident from our study, and requires a deeper observation at the molecular level to elucidate its function.

Discovery of VEGFR-2 inhibitors exerting significant anticancer activity against CD44+ and CD133+ cancer stem cells (CSCs): Reversal of TGF-β induced epithelial-mesenchymal transition (EMT) in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a malignancy characterized by neoangiogenesis, which is an augmented production of proangiogenic factors by the tumor and its adjacent infected cells. These dysregulated angiogenic factors are the therapeutic targets in anti-angiogenic drug development. The signaling pathway of vascular endothelial growth factor (VEGF)/VEGFR-2 is crucial for controlling the angiogenic responses in endothelial cells (ECs). In this study, we carried out a rational drug design approach wherein we have identified the novel orally bioavailable compound VS 8 as a potent VEGFR-2 inhibitor, which remarkably suppresses hVEGF and hVEGFR-2 expression in HUVECs and exhibits significant anti-angiogenic effects in CAM assay. Besides, VS 8 significantly induces apoptosis in HCC cell line (Hep G2). Later we examined its effectiveness against CD44+ and CD133+ CSCs. Here, VS 8 was found to be active against CSCs, and adequate for the cessation of the cell cycle at 'G₀/G₁' and 'S' phase in CD44+ and CD133+ CSCs respectively. Factually, transforming growth factor-β (TGF-β) stimulated epithelial-mesenchymal transition (EMT) induces invasion and migration of HCC cells, which results in the metastasis. Therefore, we studied the effect of VS 8 on EMT markers using flow cytometry, which suggested that VS 8 significantly upregulates E-cadherin (epithelial biomarker) and downregulates vimentin (mesenchymal biomarker). Further, VS 8 downregulates the expression of EMT-inducing transcription factors (EMT-TFs), i.e., SNAIL. Altogether, our findings indicate that VS 8 could be a promising drug candidate for cancer therapy.

Interruption of vascular endothelial growth factor receptor 2 signaling induces a proliferative pulmonary vasculopathy and pulmonary hypertension

Pulmonary arterial hypertension is a severe and progressive disease characterized by a pulmonary vascular remodeling process with expansion of collateral endothelial cells and total vessel occlusion. Endothelial cells are believed to be at the forefront of the disease process. Vascular endothelial growth factor (VEGF) and its tyrosine kinase receptor, VEGF receptor-2 (VEGFR-2), play a central role in angiogenesis, endothelial cell protection, but also in the destabilization of endothelial barrier function. Therefore, we investigated the consequences of altered VEGF signaling in an experimental model, and looked for translational correlates of this observation in patients. We performed an endothelial cell-specific conditional deletion of the kinase insert domain protein receptor (kdr) gene, coding for VEGFR-2, in C57/BL6 mice (Kdr^∆end) and held them in an environmental chamber with 10% FiO₂ or under normoxia for 6 weeks. Kdr knockout led to a mild PH phenotype under normoxia that worsened under hypoxia. Kdr^∆end mice exhibited a significant increase in pulmonary arterial wall thickness, muscularization, and VEGFR-3⁺ endothelial cells obliterating the pulmonary artery vessel lumen. We observed the same proliferative vasculopathy in our rodent model as seen in patients receiving anti-angiogenic therapy. Serum VEGF-a levels were elevated both in the experimental model and in humans receiving bevacizumab. Interrupted VEGF signaling leads to a pulmonary proliferative arteriopathy in rodents after direct ablative gene manipulation of Kdr. Histologically, similar vascular lesions can be observed in patients receiving anti-VEGF treatment. Our findings illustrate the importance of VEGF signaling for maintenance of pulmonary vascular patency.

Expression of VEGF- and tight junction-related proteins in the neocortical microvasculature of patients with drug-resistant temporal lobe epilepsy

The blood-brain barrier (BBB) maintains the optimal microenvironment for brain function. Tight junctions (TJs) allow endothelial cells to adhere to each other, leading to the formation of a barrier that prevents the penetration of most molecules via transcellular routes. Evidence has indicated that seizure-induced vascular endothelial growth factor (VEGF) type 2 receptor (VEGFR-2) pathway activation weakens TJs, inducing vasodilatation and increasing vascular permeability and subsequent brain injury. The present study focused on investigating the expression levels of VEGF-related (VEGF-A and VEGFR-2) and TJ-related proteins (claudin-5, occludin and ZO-1) in the neocortical microvasculature of patients with drug-resistant temporal lobe epilepsy (TLE). The results obtained from hippocampal sclerosis TLE (HS-TLE) patients were compared with those obtained from patients with TLE secondary to lesions (lesion-TLE) and autopsy samples. The Western blotting and immunofluorescence results showed that VEGF-A and VEGFR-2 protein expression levels were increased in HS-TLE and lesion-TLE patients compared to autopsy group. On the other hand, claudin-5 expression was higher in HS-TLE patients and lesion-TLE patients than autopsies. The expression level of occludin and ZO-1 was decreased in HS-TLE patients. Our study described modifications to the integrity of the BBB that may contribute to the pathogenesis of TLE, in which the VEGF system may play an important role. We demonstrated that the same modifications were present in both HS-TLE and lesion-TLE patients, which suggests that seizures modify these systems and that they are not associated with the establishment of epilepsy.

Design, synthesis, and cytotoxicity screening of new synthesized imidazolidine-2-thiones as VEGFR-2 enzyme inhibitors

A series of imidazolin-2-thione derivatives was synthesized and structurally confirmed through the use of different spectroscopic techniques such as infrared, nuclear magnetic resonance, and mass spectrometry along with elemental analyses. The breast cancer cell line MCF-7 was utilized in the evaluation of the cytotoxic activity of the prepared molecules. The tested molecules 3 and 7 exhibited the best results on MCF-7 cells, with mean IC₅₀ values of 3.26 and 4.31 µM, respectively. The results of the VEGFR-2 assay indicated that compounds 3 and 7 displayed a good inhibition of the VEGFR-2 kinase enzyme. Additionally, DNA flow cytometry of compounds 3 and 7 showed cell cycle arrest at the G0/G1 phase, cell apoptosis, and marked DNA fragmentation in MCF-7 cells. Finally, compounds 3 and 7 were proved to upregulate the activation of effector caspase-3/7, as presented by the caspase-3/7 green flow cytometry assay.

Design and synthesis of new 1,6-dihydropyrimidin-2-thio derivatives targeting VEGFR-2: Molecular docking and antiproliferative evaluation

A series of new 1,6-dihydropyrimidin-2-thiol derivatives (scaffold A) as VEGFR-2 inhibitors has been designed and synthesized. Compounds 3a, 3b, 3e and 4b have been selected for in vitro anticancer screening by the National Cancer Institute. Compound 3e showed remarkable anticancer activity against most of the cell lines tested, where a complete cell death against leukemia, non-small cell lung cancer, colon, CNS, melanoma, and breast cancer cell lines was observed. In vitro five dose tests showed that compound 3e had high activity against most of the tested cell lines with GI₅₀ ranging from 19 to 100 μM and selectivity ratios ranging between 0.75 and 1.71 at the GI₅₀ level. VEGFR-2-kinase was tested against 3a, 3b, 3e, 4b and sorafenib was used as a reference. Compounds 3a and 3e were the most potent analogues with IC₅₀ values of 386.4 nM and 198.7 nM against VEGFR-2, respectively, in comparison to sorafenib (IC₅₀ = 0.17 nM). The results of the docking study showed a good fitting of the new compounds to the active site of VEGFR-2 with binding free energies in the range of -9.80 to -11.25 kcal/mol compared to -12.12 kcal/mol for sorafenib. Compounds 4a-e with the hydroxyimino group had a higher affinity to VEGFR-2 than their parent derivatives 3a-e.

miR-129-5p and miR-130a-3p Regulate VEGFR-2 Expression in Sensory and Motor Neurons during Development

The wide-ranging influence of vascular endothelial growth factor (VEGF) within the central (CNS) and peripheral nervous system (PNS), for example through effects on axonal growth or neuronal cell survival, is mainly mediated by VEGF receptor 2 (VEGFR-2). However, the regulation of VEGFR-2 expression during development is not yet well understood. As microRNAs are considered to be key players during neuronal maturation and regenerative processes, we identified the two microRNAs (miRNAs)-miR-129-5p and miR-130a-3p-that may have an impact on VEGFR-2 expression in young and mature sensory and lower motor neurons. The expression level of VEGFR-2 was analyzed by using in situ hybridization, RT-qPCR, Western blot, and immunohistochemistry in developing rats. microRNAs were validated within the spinal cord and dorsal root ganglia. To unveil the molecular impact of our candidate microRNAs, dissociated cell cultures of sensory and lower motor neurons were transfected with mimics and inhibitors. We depicted age-dependent VEGFR-2 expression in sensory and lower motor neurons. In detail, in lower motor neurons, VEGFR-2 expression was significantly reduced during maturation, in conjunction with an increased level of miR-129-5p. In sensory dorsal root ganglia, VEGFR-2 expression increased during maturation and was accompanied by an overexpression of miR-130a-3p. In a second step, the functional significance of these microRNAs with respect to VEGFR-2 expression was proven. Whereas miR-129-5p seems to decrease VEGFR-2 expression in a direct manner in the CNS, miR-130a-3p might indirectly control VEGFR-2 expression in the PNS. A detailed understanding of genetic VEGFR-2 expression control might promote new strategies for the treatment of severe neurological diseases like ischemia or peripheral nerve injury.

Synthesis and molecular docking study of new pyrazole derivatives as potent anti-breast cancer agents targeting VEGFR-2 kinase

Based on the previous studies that revealed the valuable role of pyrazole scaffold in cancer management and VEGFR-2 inhibition, a new set of pyrazole conjugated with pyrazoline, triazolopyrimidine and pyrazolone moieties were synthesized and investigated for their anticancer efficiency against human breast cancer MCF-7. The anticancer screening revealed the significant sensitivity of breast carcinoma towards compounds 4b, 5c, 6c, 7b, 7c and 12c with IC₅₀ values ranging from 16.50 - 26.73 µM in comparison with tamoxifen (IC₅₀ = 23.31 µM). Moreover, the new analogues were further examined for their VEGFR-2 inhibitory activity, among the tested derivatives 5c, 6c, 7b, 7c and 12c displayed prominent inhibitory efficiency versus VEGFR-2 kinase with % inhibition ranging from 70 to 79%. Compounds 6c, 7c and 12c revealed inhibitory efficiency in nanomolar level with IC₅₀ (913.51, 225.17 and 828.23 nM, respectively) comparing to sorafenib (IC₅₀ = 186.54 nM). Flow cytometric analysis revealed that the promising compound 12c prompted pre-G1 apoptosis and cell growth cessation at G2/M phase and stimulated apoptosis via activation of caspase-3. Moreover, molecular docking study of the promising derivatives was performed to highlight their binding modes and interactions with the amino acid residues of VEGFR-2 enzyme.

A novel role for α-viniferin in suppressing angiogenesis by blocking the VEGFR-2/p70S6K signaling pathway

Angiogenesis plays important roles in pathological conditions such as cancer and inflammation as well as normal tissue development and homeostasis. Here, we investigated the effects and molecular mechanisms of α-viniferin, an oligostilbene isolated from Caragana sinica, on human umbilical vein endothelial cell responses in vitro and angiogenic sprouting in aortic rings ex vivo. α-viniferin treatment inhibited mitogen-induced HUVEC proliferation by retinoblastoma protein hypophosphorylation. In addition, α-viniferin suppressed mitogen-induced HUVEC adhesion, migration, invasion, and microvessel outgrowth. These anti-angiogenic activities of α-viniferin might be mediated through downregulation of cell cycle-related proteins, vascular endothelial growth factor receptor-2 (VEGFR-2), and matrix metalloproteinase-2. Furthermore, inactivation of VEGFR-2/p70 ribosomal S6 kinase signaling pathway was found to be involved in α-viniferin-mediated modulation of endothelial cell responses. Our results demonstrate the pharmacological functions and molecular mechanisms of α-viniferin in regulating angiogenesis, suggesting the therapeutic potential of α-viniferin to treat and prevent various angiogenesis-related diseases.

Exploration of carbamide derived pyrimidine-thioindole conjugates as potential VEGFR-2 inhibitors with anti-angiogenesis effect

The development of new small molecules from known structural motifs through molecular hybridization is one of the trends in drug discovery. In this connection, we have combined the two pharmacophoric units (pyrimidine and thioindole) in a single entity via molecular hybridization strategy along with introduction of urea functionality at C2 position of pyrimidine to increase the efficiency of H-bonding interactions. Among the synthesized conjugates 12a-aa, compound 12k was found to exhibit significant IC₅₀ values 5.85, 7.87, 6.41 and 10.43 μM against MDA-MB-231 (breast), HepG2 (liver), A549 (lung) and PC-3 (prostate) cancer cell lines, respectively. All these compounds were further evaluated for their inhibitory activities against VEGFR-2 protein. The results specified that among the tested compounds, 12d, 12e, 12k, 12l, 12p, 12q, 12t and 12u prominently suppressed VEGFR-2, with IC₅₀ values of 310-920 nM in association to the positive control (210 nM). Angiogenesis inhibition was evident by tube formation assay in HUVECs and cell-invasion by transwell assay. The mechanism of cellular toxicity on MDA-MB-231 was found through depolarisation of mitochondrial membrane potential, increased ROS production and subsequent DNA damage resulting in apoptosis induction. Moreover, clonogenic and wound healing assays designated the inhibition of colony formation and cell migration by 12k in a dose-dependent manner. Molecular docking studies also shown that compound 12k capably intermingled with catalytically active residues GLU-885, ASP-1046 of the VEGFR-2 through hydrogen-bonding interactions.

Drug-Related Hypertension Associated with the Efficacy of Apatinib on Hepatocellular Carcinoma

Purpose

We retrospectively evaluated the efficacy and safety of apatinib as a first-line treatment for advanced hepatocellular carcinoma (HCC) and explored whether drug-related hypertension (HTN) could predict its efficacy.

Patients and Methods

This retrospective analysis included patients with advanced HCC who received oral treatment with apatinib. We evaluated the effectiveness by overall survival (OS), progression-free survival (PFS), time to progression (TTP), and disease control rate (DCR), and assessed the safety of the drug based on the occurrence of adverse events. In order to explore whether apatinib-related HTN can be used as a predictor of therapeutic effect, patients were divided into an HTN group and a non-HTN group and adjusted for propensity score-matched (PSM) to reduce mixed deviation. Subgroup analyses of negative prognostic factors for advanced HCC were also performed, including alpha-fetoprotein (AFP), Child-Pugh Score, macrovascular invasion, and extrahepatic metastasis.

Results

A total of 208 patients were analyzed, of which 40.9% (n =85) developed drug-related HTN. For all patients, the OS was 13.4 months (95% CI, 12.2-14.6), the PFS was 5.7 months (95% CI, 5.1-6.3), and the TTP was 6.9 months (95% CI, 6.0-7.8). The OS of the HTN group and the non-HTN group was 17.4 months (m) and 12.5m (p=0.001), and the PFS was 7.4m and 4.7m (p=0.000), respectively. After PSM, the OS (p=0.001) and PFS (p=0.003) of the HTN group were still significantly better than the non-HTN group. Subgroup analysis suggested that overall survival was significantly longer in patients with HTN when serum AFP ≤400 μg/L or extrahepatic metastases. Moreover, OS in the HTN group increased significantly with or without macrovascular invasion. In addition, through the analysis of two groups of patients with PFS>6m and PFS≤6m, we know that the patients with drug-related HTN may develop resistance later, so they have longer survival time.

Conclusion

Apatinib demonstrates compelling anti-cancer activity and acceptable safety in advanced HCC. Apatinib-related HTN can potentially predict prolonged survival in patients with advanced HCC.

Quantitative structure activity relationship and molecular simulations for the exploration of natural potent VEGFR-2 inhibitors: an in silico anti-angiogenic study

VEGFR-2 has recently become an eye-catching molecular target for the novel therapeutic designs against cancer for its well known role in persuading angiogenesis in tumor cells. The current study set sights on the exploration of novel potent natural compound targeting VEGFR-2 via computational ligand-based modeling and database screening followed by binding pattern analysis, reactivity site prediction and MD simulation studies. The known 53 VEGFR-2 inhibitors (with IC50 ranging from 0.7 nM to 9700 nM) were headed for development of Ligand based pharmacophore model using 3 D QSAR pharmacophore generation module of DS Client. Training set inhibitors (23 compounds) were exploited to create pharmacophore model based on their chemical features. The model was validated through 30 test set inhibitors and exploited further for screening of 62,082 natural compounds from InterBioscreen natural compound database. Screened compounds further went through Drug-Likeliness study, ADMET prediction, Binding pattern analysis, In silico prediction of reactivity sites, Biological activity spectra prediction, pan assay interference compound identification and MD simulation analysis. Out of 5 screened compounds, Compound A and Compound B exhibited highest binding energy judged against the standard drug "Sorafenib". On further conducting reactivity site prediction, BAS prediction, and pan assay interference compound identification, Compound B exhibited better result which was carried forward for MD simulation study for 50 ns. MD simulation results suggested that Compound B exhibited more stable binding to the active site of VEGFR-2 without causing any conformational changes in protein-ligand complex. Thereby, the investigation proposes Compound B to hold potent antiangiogenic potential targeting VEGFR-2. [Formula: see text] Communicated by Ramaswamy H. Sarma.

Effects of Strontium-Doped β-Tricalcium Scaffold on Longitudinal Nuclear Factor-Kappa Beta and Vascular Endothelial Growth Factor Receptor-2 Promoter Activities during Healing in a Murine Critical-Size Bone Defect Model

It was hypothesized that strontium (Sr)-doped β-tricalcium phosphate (TCP)-based scaffolds have a positive effect on the regeneration of large bone defects (LBD). Readouts in our mice models were nuclear factor-kappa beta (NF-κB) activity and vascular endothelial growth factor receptor-2 (VEGFR-2) promoter activity during the healing process. A 2-mm critical-size femoral fracture was performed in transgenic NF-κB- and VEGFR-2-luciferase reporter mice. The fracture was filled with a 3D-printed β-TCP scaffold with or without Sr. A bioluminescence in-vivo imaging system was used to sequentially investigate NF-κB and VEGFR-2 expression for two months. After sacrifice, soft and osseous tissue formation in the fracture sites was histologically examined. NF-κB activity increased in the β-TCP + Sr group in the latter stage (day 40–60). VEGFR-2 activity increased in the + Sr group from days 0–15 but decreased and showed significantly less activity than the β-TCP and non-scaffold groups from days 40–60. The new bone formation and soft tissue formation in the + Sr group were significantly higher than in the β-TCP group, whereas the percentage of osseous tissue formation in the β-TCP group was significantly higher than in the β-TCP + Sr group. We analyzed longitudinal VEGFR-2 promoter activity and NF-κB activity profiles, as respective agents of angiogenesis and inflammation, during LBD healing. The extended inflammation phase and eventually more rapid resorption of scaffold caused by the addition of strontium accelerates temporary bridging of the fracture gaps. This finding has the potential to inform an improved treatment strategy for patients who suffer from osteoporosis.

Apatinib in recurrent anaplastic meningioma: a retrospective case series and systematic literature review

Up to now, no proven effective medical therapy for surgery and radiation-refractory anaplastic meningioma (AM) exists. Patients with vascular endothelial growth factor receptor 2 (VEGFR-2) positive meningiomas showed significantly shorter progression-free survival. Apatinib is a small-molecule antiangiogenic agent that selectively inhibits VEGFR-2. We report three cases of recurrent AM (VEGFR-2 positive) treated with apatinib. After apatinib treatment, the best outcome for all three patients was the partial response. The Progression-free survival was 17.3 months, 10.3 months, and 14+ months, respectively. The third patient lost follow-up after the last review. The overall survival was 28.5 months and 18 months, respectively. The main adverse events were hypertension, hand-foot syndrome, and myelosuppression. Apatinib is active in recurrent AM patients and this is the first report in the world. It is promising to launch a Phase II clinical trial of apatinib to further evaluate its efficacy on AM.

BACKGROUND

Anaplastic meningioma (AM) are rare and aggressive tumors with high recurrence rates despite optimal surgical or medical management. Up to now, no proven effective medical therapy, surgery, or radiation-refractory for AM exist. The progression-free survival (PFS) of patients with vascular endothelial growth factor receptor 2 (VEGFR-2)-positive meningiomas was significantly low. Apatinib (YN968D1) is a small-molecule antiangiogenic agent that selectively inhibits VEGFR-2.

CASE PRESENTATION

CASE #1

A 47-year-old Asian female patient with malignant meningioma underwent four operations and three radiotherapies. She was given a 500 mg apatinib daily oral treatment, and the dosage was halved to 250 mg 3 months into the treatment. According to the Response Assessment in Neuro-Oncology (RANO) evaluation criteria, the best outcome during treatment was the partial response (PR) 6 months after the treatment. The PFS was 17.3 months, whereas the overall survival (OS) was 28.5 months. The best change in the Karnofsky performance scale (KPS) was a 10-point increase. The main adverse events included anemia (grade II), thrombocytopenia (grade II), and proteinuria (grade I).

CASE #2

A 71-year-old Asian woman with AM underwent two operations and two gamma knife stereotactic radiotherapies. She was given a 500 mg apatinib daily oral treatment with a follow-up period of 18 months. apatinib was taken orally for 10 months. According to the RANO evaluation criteria, the best outcome during treatment was PR. The PFS was 10.3 months, whereas the OS was 18 months. The best change in KPS was a 20-point increase. The main adverse events included hypertension (grade II), hand-foot syndrome (grade II), and fecal ocular blood (grade II). Case #3: A 16-year-old Asian girl with AM underwent two operations and two radiotherapies. She was given a 250 mg apatinib daily oral treatment with a follow-up period of 16 months. Apatinib was taken orally for 8 months. The patient did not follow-up after the last review of the brain-enhanced magnetic resonance imaging. According to the RANO evaluation criteria, the best outcome during treatment was PR. The PFS was 14+ months, and the best change in KPS was a 10-point increase. The main adverse events included hypertension (grade I) and hand-foot syndrome (grade I).

CONCLUSION

Apatinib is actively used in treating patients with recurrent AM. A randomized trial and phase II clinical trial of this inhibitor should be performed to further evaluate its efficacy in treating malignant meningioma.

Targeting Receptor Tyrosine Kinase VEGFR-2 in Hepatocellular Cancer: Rational Design, Synthesis and Biological Evaluation of 1,2-Disubstituted Benzimidazoles

In this study, a novel series of 1,2-disubstituted benzo[d]imidazoles was rationally designed as VEGFR-2 inhibitors targeting hepatocellular carcinoma. Our design strategy is two-fold; it aimed first at studying the effect of replacing the 5-methylfuryl moiety of the well-known antiangiogenic 2-furylbenzimidazoles with an isopropyl moiety on the VEGFR-2 inhibitory activity and the cytotoxic activity. Our second objective was to further optimize the structures of the benzimidazole derivatives through elongation of the side chains at their one-position for the design of more potent type II-like VEGFR-2 inhibitors. The designed 1,2-disubstituted benzimidazoles demonstrated potent cytotoxic activity against the HepG2 cell line, reaching IC₅₀ = 1.98 μM in comparison to sorafenib (IC₅₀ = 10.99 μM). In addition, the synthesized compounds revealed promising VEGFR-2 inhibitory activity in the HepG2 cell line, e.g., compounds 17a and 6 showed 82% and 80% inhibition, respectively, in comparison to sorafenib (% inhibition = 92%). Studying the effect of 17a on the HepG2 cell cycle demonstrated that 17a arrested the cell cycle at the G2/M phase and induced a dose-dependent apoptotic effect. Molecular docking studies of the synthesized 1,2-disubstituted benzimidazoles in the VEGFR-2 active site displayed their ability to accomplish the essential hydrogen bonding and hydrophobic interactions for optimum inhibitory activity.

Expression and distribution of HIF-1α, HIF-2α, VEGF, VEGFR-2 and HIMF in the kidneys of Tibetan sheep, plain sheep and goat

BACKGROUND

The objective of this study was to detect the expression and distribution characteristics of five proteins (the hypoxia-inducible factor 1alpha [HIF-1a], HIF-2a, vascular endothelial growth factor [VEGF], VEGF-2 receptor [VEGFR-2] and hypoxia-induced mitogenic factor [HIMF]) in kidney of Tibetan sheep, plain sheep and goat. The results will provide the basic information for the comparative study of sheep breeds living at different altitudes.

MATERIALS AND METHODS

The kidney tissues were collected from healthy adult Tibetan sheep, plain sheep and goats and made into paraffin sections. Histological characteristics were assessed by haematoxylin and eosin staining. Expressions of HIF-1a, HIF-2a, VEGF, VEGFR-2 and HIMF proteins were measured by immunohistochemical staining.

RESULTS

Immunohistochemistry results showed that the positive expression signals of HIF-1a, HIF-2a, VEGF and VEGFR-2 were detected in epithelial cells of renal tubules and collecting tubules, renal corpuscles in the kidneys of the three sheep breeds. Positive expression signals of HIMF were detected in epithelial cells of proximal tubules and distal tubules in Tibetan sheep and epithelial cells of distal tubules in goat. Immunostaining intensity of HIF-1a, HIF-2a, VEGF and VEGFR-2 proteins in Tibetan sheep was significantly higher than that in both plain sheep and goat (p < 0.05). Immunostaining intensity of HIMF in Tibetan sheep was higher than goat (p < 0.05). Positive expression signals of HIMF were not detected in plain sheep.

CONCLUSIONS

The expression and distribution characteristics of HIF-1a, HIF-2a, VEGF, VEGFR-2 and HIMF in the studied kidney tissues suggested that these proteins may be related to the physiological regulation of Tibetan sheep kidney in hypoxia environment, and therefore might be important regulating proteins for Tibetan sheep to adapt to high altitude hypoxia environment.

Genetic interaction analysis of VEGF-A rs3025039 and VEGFR-2 rs2071559 identifies a genetic profile at higher risk to develop nodular goiter

CONTEXT

Nodular goiter in patients from areas of iodine deficiency is due to the growth of follicular and endothelial cells, involving different vascular-related growth factors in its pathogenesis.

OBJECTIVE

The aim of our study was to examine the association of known single polymorphisms of vascular endothelial growth factor-A [VEGF-A], VEGF receptor-2 [VEGFR-2] and hypoxia-inducible factor-1α [HIF-1α] genes or their genetic interactions with the risk of nodular goiter development.

PATIENTS AND METHODS

116 normal subjects, without any thyroid disease, and 108 subjects with nodular goiter [subjects with goiter and at least one thyroid nodule of > 1 cm of maximum size and in absence of signs of autoimmunity] were selected from a homogeneous population living in a mild iodine deficiency geographic area. Analyses were performed on germline DNA obtained from blood samples and VEGF-A rs3025039, VEGFR-2 rs2071559, and HIF-1αrs11549465 SNPs were investigated by real-time PCR technique. The multifactor dimensionality reduction [MDR] methodology was applied to investigate the genetic interaction between SNPs. Hardy-Weinberg equilibrium was performed.

RESULTS

None of the studied polymorphisms were individually associated with a higher risk to develop nodular goiter [P > 0.05]. The combination of the VEGF-A rs3025039 and VEGFR-2 rs2071559 polymorphisms had the highest accuracy of 0.58 [P = 0.018] and the interaction of some genotypes was significantly associated with the risk of nodular goiter development.

CONCLUSIONS

Our results support a genetic interaction between the VEGF-A rs3025039 and VEGFR-2 rs2071559 polymorphisms as a predictor of the risk to develop nodular goiter in subjects coming from an area with mild iodine deficiency.

Novel Anticancer Fused Pyrazole Derivatives as EGFR and VEGFR-2 Dual TK Inhibitors

EGFR and VEGFR-2 represent promising targets for cancer treatment as they are very important in tumor development as well as in angiogenesis and metastasis. In this work, 6-amino-4-(2-bromophenyl)-3-methyl-1,4-dihydropyrano[2,3-c]pyrazole-5-carbonitrile 1 and (E)-4-(2-Bromobenzylidene)-5-methyl-2,4-dihydro-3H-pyrazol-3-one 11 were selected as starting materials to synthesize different fused pyrazole derivatives; dihydropyrano[2,3-c]pyrazole 1, 2, 7–9, and 15, pyrazolo[4′,3′:5,6]pyrano[2,3-d]pyrimidine 3–6, pyrazolo[3,4-d]pyrimidine 12 and 13, and pyrazolo[3,4-c]pyrazole 14 derivatives were synthesized to evaluate their anticancer activity against HEPG2 human cancer cell lines compared to erlotinib and sorafenib as reference drugs. Seven compounds 1, 2, 4, 8, 11, 12, and 15 showed nearly 10 fold higher activity than erlotinib (10.6 μM) with IC₅₀ ranging from 0.31 to 0.71 μM. In vitro EGFR and VEGFR-2 inhibitory activity were performed for the synthesized compounds, and the results identified compound 3 as the most potent EGFR inhibitor (IC₅₀ = 0.06 μM) and compound 9 as the most potent VEGFR-2 inhibitor (IC₅₀ = 0.22 μM). Moreover, compounds 9 and 12 revealed potent dual EGFR and VEGFR-2 inhibition, and these results were supported by docking studies of these two compounds within the active sites of both enzymes.

Apatinib in Patients with Relapsed or Refractory Diffuse Large B Cell Lymphoma: A Phase II, Open-Label, Single-Arm, Prospective Study

Purpose

Treatment options for relapsed or refractory diffuse large B-cell lymphoma (RR DLBCL) represent an unmet medical need. Apatinib is a new oral tyrosine kinase inhibitor mainly targeting vascular endothelial growth factor receptor-2 (VEGFR-2) to inhibit tumour angiogenesis. In the present study, we evaluated the efficacy and safety of apatinib for patients with RR DLBCL.

Patients and Methods

In this phase II, open-label, single-arm, prospective study, we enrolled patients aged 14–70 years with treatment failure of at least two chemotherapeutic regimens using Simon’s two-stage design. All patients were administered apatinib at an initial dose of 500 mg on a 4-week cycle at home and visited the outpatient clinic every two cycles to evaluate efficacy and to record adverse events. We considered objective response rate (ORR) as the primary end point, and progression-free survival (PFS), and overall survival (OS) plus duration of response (DoR) as the secondary end point. (This trial was registered at ClinicalTrials.gov, identifier: NCT03376958.).

Results

From January 2017 to February 2019, we screened 35 patients and enrolled 32 eligible patients. At the cutoff point (April 2019), we noted 2 (6.3%) complete responses, 12 (37.5%) partial responses, and 9 (28.1%) stable diseases, attributing to an ORR of 43.8% and a disease control rate of 71.9%. The median PFS and OS were 6.9 (95% confidence interval [CI], 5.8–7.9) and 7.9 months (95% CI, 7.0–8.7), respectively. The median DoR was 5.0 months (95% CI, 3.5–6.5) for patients who achieved PR. The most common grade 3–4 adverse events (AE) were hypertension (12.6%), hand–foot syndrome (9.4%), and leucopenia (6.3%). No apatinib-related deaths were noted.

Conclusion

Home administration of apatinib shows promising efficacy and manageable AEs in patients with RR DLBCL.

Cancer neovasculature-targeted near-infrared photoimmunotherapy (NIR-PIT) for gastric cancer: different mechanisms of phototoxicity compared to cell membrane-targeted NIR-PIT

BACKGROUND

Near-infrared photoimmunotherapy (NIR-PIT) constitutes a new class of molecular-targeted theranostics utilizing monoclonal antibody (mAb)-photosensitizer conjugates and NIR light. In this study, we developed a new type of NIR-PIT targeting vascular endothelial growth factor receptor 2 (VEGFR-2) expressed on vascular endothelium in an experimental gastric cancer model and evaluated the feasibility by comparing conventional NIR-PIT targeting cancer cell membrane in vitro and in vivo.

METHODS

HER2-positive human gastric cancer cells, NCI-N87, were used for the experiments. Anti-HER2 mAb, trastuzumab and anti-VEGFR-2 mAb, DC101 were conjugated to photosensitizer, IR700. Phototoxicity in response to NIR-PIT were investigated in vitro and in vivo. Microvessel densities, as an indicator of angiogenesis, were counted in harvested xenografts after NIR-PIT to elucidate the mechanism.

RESULTS

DC101-IR700 did not induce phototoxic effect in vitro because of the absence of expression of VEGFR-2 in NCI-N87 cancer cells. However, it induced an antitumor effect in NCI-N87 xenograft tumors accompanied with damage in tumor neovasculature as determined by decreasing tumor microvessel density, which represents a different mechanism than that of conventional NIR-PIT targeting antigens expressed on the tumor cell membrane.

CONCLUSION

We demonstrated a new approach of NIR-PIT utilizing a target on vascular endothelium, such as VEGFR-2, and this treatment might lead to the development of a new therapeutic strategy for human gastric cancer.

Hyperglycemia-induced endothelial dysfunction is alleviated by thioredoxin mimetic peptides through the restoration of VEGFR-2-induced responses and improved cell survival

BACKGROUND

Diabetes mellitus is an important cardiovascular risk factor characterized by elevated plasma glucose levels. High glucose (HG) negatively influences endothelial cell (EC) function, which is characterized by the inability of ECs to respond to vascular endothelial growth factor (VEGF-A) stimulation. We aimed to identify potential strategies to improve EC function in diabetes.

METHODS AND RESULTS

Human umbilical cord endothelial cells (HUVECs) were subjected to hyperglycemic milieu by exposing cells to HG together with glucose metabolite, methylglyoxal (MG) in vitro. Hyperglycemic cells showed reduced chemotactic responses towards VEGF-A as revealed by Boyden chamber migration assays, indicating the development of "VEGF resistance" phenotype. Furthermore, HG/MG-exposed cells were defective in their general migratory and proliferative responses and were in a pro-apoptotic state. Mechanistically, the exposure to HG/MG resulted in reactive oxygen species (ROS) accumulation which is secondary to the impairment of thioredoxin (Trx) activity in these cells. Pharmacological and genetic targeting of Trx recapitulated VEGF resistance. Functional supplementation of Trx using thioredoxin mimetic peptides (TMP) reversed the HG/MG-induced ROS generation, improved the migration, proliferation, survival and restored VEGF-A-induced chemotaxis and sprouting angiogenesis of hyperglycemic ECs. Importantly, TMP treatment reduced ROS accumulation and improved VEGF-A responses of placental arterial endothelial cells isolated from gestational diabetes mellitus patients.

CONCLUSIONS

Our findings suggest a putative role for Trx in modulating EC function and its functional impairment in HG conditions contribute to EC dysfunction. Supplementation of TMP could be used as a novel strategy to improve endothelial cell function in diabetes.

Phosphorylation of Dab2 is involved in inhibited VEGF-VEGFR-2 signaling induced by downregulation of syndecan-1 in glomerular endothelial cell

Disabled-2 (Dab2) and PAR-3 (partitioning defective 3) are reported to play critical roles in maintaining retinal microvascular endothelial cells biology by regulating VEGF-VEGFR-2 signaling. The role of Dab2 and PAR-3 in glomerular endothelial cell (GEnC) is unclear. In this study, we found that, no matter whether with vascular endothelial growth factor (VEGF) treatment or not, decreased expression of Dab2 could lead to cell apoptosis by preventing activation of VEGF-VEGFR-2 signaling in GEnC, accompanied by reduced membrane VEGFR-2 expression. And silencing of PAR-3 gene expression caused increased apoptosis of GEnC by inhibiting activation of VEGF-VEGFR-2 signaling and membrane VEGFR-2 expression. In our previous research, we found that the silencing of syndecan-1 gene expression inhibited VEGF-VEGFR-2 signaling by modulating internalization of VEGFR-2. And our further research demonstrated that downregulation of syndecan-1 lead to no significant change in the expression of Dab2 and PAR-3 both at messenger RNA and protein levels in GEnC, while phosphorylation of Dab2 was significantly increased in GEnC transfected with Dab2 small interfering RNA (siRNA) compared with control siRNA. Atypical protein kinase C (aPKC) could induce phosphorylation of Dab2, thus negatively regulating VEGF-VEGFR-2 signaling. And we found that decreased expression of syndecan-1 lead to activation of aPKC, and aPKC inhibitor treatment could block phosphorylation of Dab2 in GEnC. Besides, aPKC inhibitor treatment could activate VEGF-VGEFR-2 signaling in GEnC transfected with syndecan-1 siRNA in a dose-dependent manner. In conclusion, we speculated that phosphorylation of Dab2 is involved in preventing activation of VEGF-VEGFR-2 signaling in GEnC transfected with syndecan-1 siRNA. This provides a new target for the therapy of GEnC injury and kidney disease.

AT-533, a novel Hsp90 inhibitor, inhibits breast cancer growth and HIF-1α/VEGF/VEGFR-2-mediated angiogenesis in vitro and in vivo

The inhibition of angiogenesis is suggested to be an attractive strategy for cancer therapeutics. Heat shock protein 90 (Hsp90) is closely related to tumorigenesis as it regulates the stabilization and activated states of many client proteins that are essential for cell survival and tumor growth. Here, we investigated the mechanism whereby AT-533, a novel Hsp90 inhibitor, inhibits breast cancer growth and tumor angiogenesis. Based on our results, AT-533 suppressed the tube formation, cell migration, and invasion of human umbilical vein endothelial cells (HUVECs), and was more effective than the Hsp90 inhibitor, 17-AAG. Furthermore, AT-533 inhibited angiogenesis in the aortic ring, Matrigel plug, and chorioallantoic membrane (CAM) models. Mechanically, AT-533 inhibited the activation of VEGFR-2 and the downstream pathways, including Akt/mTOR/p70S6K, Erk1/2 and FAK, in HUVECs, and the viability of breast cancer cells and the HIF-1α/VEGF signaling pathway under hypoxia. In vivo, AT-533 also inhibited tumor growth and angiogenesis by inducing apoptosis and the HIF-1α/VEGF signaling pathway in breast cancer cells. Taken together, our findings indicate that the Hsp90 inhibitor, AT-533, suppresses breast cancer growth and angiogenesis by blocking the HIF-1α/VEGF/VEGFR-2 signaling pathway. AT-533 may thus be a potentially useful drug candidate for breast cancer therapy.

Discovery of 8-Amino-Substituted 2-Phenyl-2,7-Naphthyridinone Derivatives as New c-Kit/VEGFR-2 Kinase Inhibitors

The 2,7-naphthyridone scaffold has been proposed as a novel lead structure of MET inhibitors by our group. To broaden the application of this new scaffold, a series of 8-amino-substituted 2-phenyl-2,7-naphthyridin-1(2H)-one derivatives were designed and synthesized. Preliminary biological screening resulted in the discovery of a new lead of c-Kit and VEGFR-2 kinase inhibitors. Compound 9k exhibited excellent c-Kit inhibitory activity, with an IC₅₀ value of 8.5 nM, i.e., it is 38.8-fold more potent than compound 3 (IC₅₀ of 329.6 nM). Moreover, the compounds 10l and 10r exhibited good VEGFR-2 inhibitory activity, with IC₅₀ values of 56.5 and 31.7 nM, respectively, i.e., they are 5.0–8.8-fold more potent than compound 3 (IC₅₀ of 279.9 nM). Molecular docking experiments provided further insight into the binding interactions of the new lead compounds with c-Kit and VEGFR-2 kinase. In this study, an 8-amino-substituted 2-phenyl-2,7-naphthyridin-1(2H)-one scaffold was identified as the new lead structure of c-Kit and VEGFR-2 kinase inhibitors.

Design, synthesis and antitumor activity of aromatic urea-quinazolines

Background: Gefitinib and sorafenib have been proved effective for the treatment of cancers in clinical practice for years. Materials & methods: We intended to integrate the structural features of gefitinib and sorafenib and construct structurally unique 7-aromatic ureido-4-anilinoquinazolines. Results: Most of the targets exhibited promising antitumor activities. 8u showed excellent antitumor activities against the three tested cell lines (IC₅₀, 0.81-2.49 μM). The enzymatic, apoptosis assay of 8u were also performed to study their preliminary action of mechanism. Conclusion: 8u deserve further research as antitumor agents.