VEGFR-2 expression in carcinoid cancer cells and its role in tumor growth and metastasis

Phase II study of pembrolizumab and lenvatinib in advanced well-differentiated neuroendocrine tumors

BACKGROUND

Immune checkpoint inhibitors (CPIs) have not been shown to be active in well-differentiated neuroendocrine tumors (NETs), with response rates <5%. Lenvatinib is a multitargeted tyrosine kinase inhibitor which binds to vascular endothelial growth factor and fibroblast growth factor receptors and has demonstrated efficacy in pancreatic and gastrointestinal NETs [44% and 16% objective radiographic response rate (ORR), respectively]. The combination of antiangiogenic and CPI therapies can be synergistic. We therefore evaluated the combination of lenvatinib and pembrolizumab in well-differentiated gastrointestinal (GI) and thoracic NETs.

PATIENTS AND METHODS

A prospective, phase II trial evaluated patients with advanced GI/thoracic NETs (pancreatic NETs were excluded due to high response rate of lenvatinib monotherapy in this patient population), with evidence of progression within 8 months of study entry and at least two prior lines of systemic therapy. Patients received lenvatinib 20 mg daily and pembrolizumab 200 mg intravenously every 3 weeks until unacceptable toxicity or progression of disease. Primary endpoint was objective response rate, and an interim analysis was planned once 20 patients were enrolled. Four ORRs were required to continue enrollment.

RESULTS

Twenty patients were enrolled on protocol from April 2021 to January 2022 (nine small intestine, five lung, two thymic, two unknown primary, one cecal, one presacral primaries). Two patients (10%) achieved a partial response (atypical lung and small intestinal primaries). Median progression-free survival (PFS) was 8 months (95% confidence interval 5.8-10.2 months). Twelve (60%) patients experienced probably or definitely associated grade 3 adverse events (10 hypertension). Fourteen patients (70%) required dose reductions or discontinued one of the medications. Two patients discontinued treatment before radiographic assessment.

CONCLUSIONS

The combination of pembrolizumab and lenvatinib did not show sufficient response in patients with NETs to warrant continued enrollment on trial.

Discovery of new VEGFR-2 inhibitors and apoptosis inducer-based thieno[2,3-d]pyrimidine

Background: VEGFR-2 is a key regulator of cancer cell proliferation, migration and angiogenesis. Aim: Development of thieno[2,3-d]pyrimidine derivatives as potential anti-cancer agents targeting VEGFR-2. Methods: Seven in vitro and nine in silico studies were conducted. Results: Compound 10d demonstrated strong anticancer potential, boosting apoptosis based on VEGFR-2 inhibition. It arrested the S phase of the cell cycle and upregulated the apoptotic factors. Docking and molecular dynamics simulation studies confirm the stability of the VEGFR-2-10d complex and suggest that these compounds have good binding affinities to VEGFR-2. In addition, the drug-likeness was confirmed. Conclusion: Thieno[2,3-d]pyrimidines, particularly compound 10d, has good anticancer effects and may contribute to the development of new anticancer therapies.

In vitro and in silico evaluation of new thieno[2,3-d]pyrimidines as anti-cancer agents and apoptosis inducers targeting VEGFR-2

In this study, new thieno[2,3-d]pyrimidine derivatives that could have potential anticancer activity by inhibiting the VEGFR-2 receptor have been designed, synthesized, and investigated. The thieno[2,3-d]pyrimidine derivatives showed strong in vitro abilities to inhibit VEGFR-2 and to prevent cancer cell growth in two different types of cancer cells, MCF-7 and HepG2. Particularly, compound 22 showed the most potent anti-VEGFR-2 activity with an IC50 value of 0.58 µM. Additionally, compound 22 exhibited good anti-proliferative activity against both MCF-7 and HepG2 cancer cell lines, with IC50 values of 11.32 ± 0.32 and 16.66 ± 1.22 µM, respectively. Further investigations revealed that compound 22 induced cell cycle arrest at the G2/M phase and promoted both early and late apoptosis in the MCF-7 cancer cells. Compound 22 also increased the level of BAX (2.8-fold), and reduced the level of Bcl-2 (2.2-fold), hence increasing the rate of apoptosis. Compound 22 also revealed 2.9-fold and 2.8-fold higher levels of caspase-8 and caspase-9, respectively, in the treated MCF-7 cancer cells compared to the control cell lines. The MD simulations showed that the VEGFR-2-22 complex was structurally and energytically stable over 100 ns, while the MM-GBSA study indicated its stable thermodynamic behavior. The bi-dimensional projection analysis confirmed the proper binding of the VEGFR-2-22 complex, while the DFT studies provided optimized geometry, charge distribution, FMO, ESP, the total density of state, and QTAIM maps of compound 22. Finally, computational ADMET studies were performed to assess the drug development potential of the thieno[2,3-d]pyrimidine derivatives. Overall, this study suggests that compound 22 has the potential as an anticancer lead compound by inhibiting VEGFR-2, which may be a guide for future drug design and development.

Synthesis, biological evaluation and computer-aided discovery of new thiazolidine-2,4-dione derivatives as potential antitumor VEGFR-2 inhibitors

In this study, novel VEGFR-2-targeting thiazolidine-2,4-dione derivatives with potential anticancer properties were designed and synthesized. The ability of the designed derivatives to inhibit VEGFR-2 and stop the growth of three different cancer cell types (HT-29, A-549, and HCT-116) was examined in vitro. The IC50 value of compound 15, 0.081 μM, demonstrated the best anti-VEGFR-2 potency. Additionally, compound 15 showed remarkable anti-proliferative activities against the tested cancer cell lines, with IC50 values ranging from 13.56 to 17.8 μM. Additional flow cytometric investigations showed that compound 15 increased apoptosis in HT-29 cancer cells (from 3.1% to 31.4%) arresting their growth in the S phase. Furthermore, compound 15's apoptosis induction in the same cell line was confirmed by increasing the levels of BAX (4.8-fold) and decreasing Bcl-2 (2.8-fold). Also, compound 15 noticeably increased caspase-8 and caspase-9 levels by 1.7 and 3.2-fold, respectively. Computational methods were used to perform molecular analysis of the VEGFR-2-15 complex. Molecular dynamics simulations and molecular docking were utilized to analyze the complex's kinetic and structural characteristics. Protein-ligand interaction profiler analysis (PLIP) determined the 3D interactions and binding conformation of the VEGFR-2-15 complex. DFT analyses also provided insights into the 3D geometry, reactivity, and electronic characteristics of compound 15. Computational ADMET and toxicity experiments were conducted to determine the potential of the synthesized compounds for therapeutic development. The study's findings suggest that compound 15 might be an effective anticancer lead compound and could guide future attempts to develop new drugs.

Design, synthesis, anti-proliferative evaluation, docking, and MD simulation studies of new thieno[2,3-d]pyrimidines targeting VEGFR-2

In this work, new thieno[2,3-d]pyrimidine-derived compounds possessing potential anticancer activities were designed and synthesized to target VEGFR-2. The thieno[2,3-d]pyrimidine derivatives were tested in vitro for their abilities to inhibit VEGFR-2 and to prevent cancer cell growth in two types of cancer cells, MCF-7 and HepG2. Compound 18 exhibited the strongest anti-VEGFR-2 potential with an IC50 value of 0.084 μM. Additionally, it displayed excellent proliferative effects against MCF-7 and HepG2 cancer cell lines, with IC50 values of 10.17 μM and 24.47 μM, respectively. Further studies revealed that compound 18 induced cell cycle arrest in G2/M phase and promoted apoptosis in MCF-7 cancer cells. Apoptosis was stimulated by compound 18 by increasing BAX (3.6-fold) and decreasing Bcl-2 (3.1-fold). Additionally, compound 18 significantly raised the levels of caspase-8 (2.6-fold) and caspase-9 (5.4-fold). Computational techniques were also used to investigate the VEGFR-2-18 complex at a molecular level. Molecular docking and molecular dynamics simulations were performed to assess the structural and energetic features of the complex. The protein-ligand interaction profiler analysis identified the 3D interactions and binding conformation of the VEGFR-2-18 complex. Essential dynamics (ED) study utilizing principal component analysis (PCA) described the protein dynamics of the VEGFR-2-18 complex at various spatial scales. Bi-dimensional projection analysis confirmed the proper binding of the VEGFR-2-18 complex. In addition, the DFT studies provided insights into the structural and electronic properties of compound 18. Finally, computational ADMET and toxicity studies were conducted to evaluate the potential of the thieno[2,3-d]pyrimidine derivatives for drug development. The results of the study suggested that compound 18 could be a promising anticancer agent that may provide effective treatment options for cancer patients. Furthermore, the computational techniques used in this research provided valuable insights into the molecular interactions of the VEGFR-2-18 complex, which may guide future drug design efforts. Overall, this study highlights the potential of thieno[2,3-d]pyrimidine derivatives as a new class of anticancer agents and provides a foundation for further research in this area.

Regulation of VEGFR2 and AKT Signaling by Musashi-2 in Lung Cancer

Lung cancer is the most frequently diagnosed cancer type and the leading cause of cancer-related deaths worldwide. Non-small cell lung cancer (NSCLC) represents most of the diagnoses of lung cancer. Vascular endothelial growth factor receptor-2 (VEGFR2) is a member of the VEGF family of receptor tyrosine kinase proteins, which are expressed on both endothelial and tumor cells, are one of the key proteins contributing to cancer development, and are involved in drug resistance. We previously showed that Musashi-2 (MSI2) RNA-binding protein is associated with NSCLC progression by regulating several signaling pathways relevant to NSCLC. In this study, we performed Reverse Protein Phase Array (RPPA) analysis of murine lung cancer, which suggests that VEGFR2 protein is strongly positively regulated by MSI2. Next, we validated VEGFR2 protein regulation by MSI2 in several human lung adenocarcinoma cell line models. Additionally, we found that MSI2 affected AKT signaling via negative PTEN mRNA translation regulation. In silico prediction analysis suggested that both VEGFR2 and PTEN mRNAs have predicted binding sites for MSI2. We next performed RNA immunoprecipitation coupled with quantitative PCR, which confirmed that MSI2 directly binds to VEGFR2 and PTEN mRNAs, suggesting a direct regulation mechanism. Finally, MSI2 expression positively correlated with VEGFR2 and VEGF-A protein levels in human lung adenocarcinoma samples. We conclude that the MSI2/VEGFR2 axis contributes to lung adenocarcinoma progression and is worth further investigations and therapeutic targeting.

Regulation of VEGFR2 and AKT signaling by Musashi-2 in lung cancer

Lung cancer is the most frequently diagnosed cancer type and the leading cause of cancer-related deaths worldwide. Non-small cell lung cancer (NSCLC) represents most of the lung cancer. Vascular endothelial growth factor receptor-2 (VEGFR2) is a member of the VEGF family of receptor tyrosine kinase proteins, expressed on both endothelial and tumor cells which is one of the key proteins contributing to cancer development and involved in drug resistance. We previously showed that Musashi-2 (MSI2) RNA-binding protein is associated with NSCLC progression by regulating several signaling pathways relevant to NSCLC. In this study, we performed Reverse Protein Phase Array (RPPA) analysis of murine lung cancer which nominated VEGFR2 protein as strongly positively regulated by MSI2. Next, we validated VEGFR2 protein regulation by MSI2 in several human NSCLC cell line models. Additionally, we found that MSI2 affected AKT signaling via negative PTEN mRNA translation regulation. In silico prediction analysis suggested that both VEGFR2 and PTEN mRNAs have predicted binding sites for MSI2. We next performed RNA immunoprecipitation coupled with quantitative PCR which confirmed that MSI2 directly binds to VEGFR2 and PTEN mRNAs, suggesting direct regulation mechanism. Finally, MSI2 expression positively correlated with VEGFR2 and VEGF-A protein levels in human NSCLC samples. We conclude that MSI2/VEGFR2 axis contributes to NSCLC progression and is worth further investigations and therapeutic targeting.

New [1,2,4]triazolo[4,3-c]quinazoline derivatives as vascular endothelial growth factor receptor-2 inhibitors and apoptosis inducers: Design, synthesis, docking, and antiproliferative evaluation

In continuation of our previous efforts in the field of design and synthesis of vascular endothelial growth factor receptor (VEGFR)-2 inhibitors, a new series of [1,2,4]triazolo[4,3-c]quinazoline derivatives were designed and synthesized as modified analogs of some reported VEGFR-2 inhibitors. The synthesized compounds were designed to have the essential pharmacophoric features of VEGFR-2 inhibitors. Antiproliferative activities of the synthesized compounds were investigated against two tumor cell lines (HepG2 and HCT-116) using sorafenib as a positive control. Compound 10k emerged as the most promising antiproliferative agent with IC₅₀ values of 4.88 and 5.21 µM against HepG2 and HCT-116 cells, respectively. Also, it showed the highest inhibitory activity against VEGFR-2 with an IC₅₀ value of 53.81 nM compared to sorafenib (IC₅₀  = 44.34 nM). Cell cycle analysis revealed that compound 10k can arrest HepG2 cells at both the S and G2/M phases. In addition, this compound produced a tenfold increase in apoptotic cells compared to the control. Furthermore, the effect of compound 10k on the expression level of BAX, Bcl-2, and caspase-3 was assessed. This compound caused a 3.35-fold increase in BAX expression levels and a 1.25-fold reduction in Bcl-2 expression levels. The BAX/Bcl-2 ratio was calculated to be 4.57, indicating a promising apoptotic effect. It also showed a significant increase in the level of caspase-3 (4.12-fold) compared to the control cells. In silico docking, absorption, distribution, metabolism, excretion, and toxicity, and toxicity studies were performed for the synthesized compounds to investigate their binding patterns against the proposed biological target (VEGFR-2) and to assess the drug-likeness characters.

Mediating EGFR-TKI Resistance by VEGF/VEGFR Autocrine Pathway in Non-Small Cell Lung Cancer

Simple Summary

Non-small cell lung cancer (NSCLC) patients acquire resistance to tyrosine kinase inhibitors (TKIs) via EGFR mutations or overexpression of vascular endothelial growth factor receptor-2 (VEGFR-2). In this study, we elucidated the mechanism of EGFR-TKI resistance mediated by VEGF/VEGFR in EGFR-mutated NSCLC cell lines and Erlotinib-resistant cell lines as compared to parental cell lines. Increased expression of VEGF, VEGFR-2, and NP1 was observed in Erlotinib-resistant cell lines. Furthermore, we observed an increased efficacy of Erlotinib in combination with a VEGFR-2 inhibitor in Erlotinib-resistant cell lines. Late-stage NSCLC patients with high expression of VEGFR-2 had shorter survival times compared to patients with low VEGFR-2 expression. These results indicate that VEGFR-2 may play a key role in EGFR-TKI resistance that can be overcome with a combination treatment of Erlotinib and a VEGFR-2 inhibitor, which may serve as an effective treatment option for NSCLC patients with EGFR mutations.

Abstract

NSCLC treatment includes targeting of EGFR with tyrosine kinase inhibitors (TKIs) such as Erlotinib; however, resistance to TKIs is commonly acquired through T790M EGFR mutations or overexpression of vascular endothelial growth factor receptor-2 (VEGFR-2). We investigated the mechanisms of EGFR-TKI resistance in NSCLC cell lines with EGFR mutations or acquired resistance to Erlotinib. These studies showed upregulated gene and protein expression of VEGF, VEGFR-2, and a VEGF co-receptor neuropilin-1 (NP-1) in Erlotinib-resistant (1.4–5.3-fold) and EGFR double-mutant (L858R and T790M; 4.1–8.3-fold) NSCLC cells compared to parental and EGFR single-mutant (L858R) NSCLC cell lines, respectively. Immunofluorescence and FACS analysis revealed increased expression of VEGFR-2 and NP-1 in EGFR-TKI-resistant cell lines compared to TKI-sensitive cell lines. Cell proliferation assays showed that treatment with a VEGFR-2 inhibitor combined with Erlotinib lowered cell survival in EGFR double-mutant NSCLC cells to 9% compared to 72% after treatment with Erlotinib alone. Furthermore, Kaplan–Meier analysis revealed shorter median survival in late-stage NSCLC patients with high vs. low VEGFR-2 expression (14 mos vs. 21 mos). The results indicate that VEGFR-2 may play a key role in EGFR-TKI resistance and that combined treatment of Erlotinib with a VEGFR-2 inhibitor may serve as an effective therapy in NSCLC patients with EGFR mutations.

Evaluation of antitumor effects of VEGFR-2 inhibitor F16 in a colorectal xenograft model

OBJECTIVES

Colorectal cancer (CRC) is the third most prevalent type of cancer in the United States. The treatment options for cancer include surgery, chemotherapy, radiation, and/or targeted therapy, which show significant improvement in overall survival. Among the various available treatments, antagonizing VEGF/VEGFR-2 pathways have shown effectiveness in limiting colorectal cancer growth and improving clinical outcomes. In this regard, we hypothesized that F16, a novel VEGFR-2 inhibitor, would control colorectal cancer growth by blocking the VEGFR-2 singling pathway in both in vitro and in vivo conditions. Therefore, the current study was aimed to analyze the efficacy of F16 on the growth of Colo 320DM cells under in vitro and in vivo conditions.

RESULTS

Human RT² profiler PCR array analysis results clearly showed that angiogenesis and anti-apoptosis-related gene expressions were significantly reduced in HUVEC cells after F16 (5 μM) treatment. In addition, Western blot results revealed that F16 attenuated the downstream signaling of the VEGFR-2 pathway in HUVEC cells by up-regulating the p53 and p21 levels and down-regulating the p-AKT and p-FAK levels. Accordingly, F16 confirmed potent cytotoxic effects against the cell viability of Colo 320DM tumors, with an IC₅₀ value of 9.52 ± 1.49 µM. Furthermore, treatment of mice implanted with Colo 320DM xenograft tumors showed a significant reduction in tumor growth and increases in survival rate compared to controls. Immunohistochemistry analysis of tumor tissues showed a reduction in CD31 levels also in F16 treated groups.

CONCLUSIONS

These results justify further evaluation of F16 as a potential new therapeutic agent for treating colorectal cancers.

Receptor Tyrosine Kinases and Their Signaling Pathways as Therapeutic Targets of Curcumin in Cancer

Receptor tyrosine kinases (RTKs) are transmembrane cell-surface proteins that act as signal transducers. They regulate essential cellular processes like proliferation, apoptosis, differentiation and metabolism. RTK alteration occurs in a broad spectrum of cancers, emphasising its crucial role in cancer progression and as a suitable therapeutic target. The use of small molecule RTK inhibitors however, has been crippled by the emergence of resistance, highlighting the need for a pleiotropic anti-cancer agent that can replace or be used in combination with existing pharmacological agents to enhance treatment efficacy. Curcumin is an attractive therapeutic agent mainly due to its potent anti-cancer effects, extensive range of targets and minimal toxicity. Out of the numerous documented targets of curcumin, RTKs appear to be one of the main nodes of curcumin-mediated inhibition. Many studies have found that curcumin influences RTK activation and their downstream signaling pathways resulting in increased apoptosis, decreased proliferation and decreased migration in cancer both in vitro and in vivo. This review focused on how curcumin exhibits anti-cancer effects through inhibition of RTKs and downstream signaling pathways like the MAPK, PI3K/Akt, JAK/STAT, and NF-κB pathways. Combination studies of curcumin and RTK inhibitors were also analysed with emphasis on their common molecular targets.

Golgi Phosphoprotein 3 Confers Radioresistance via Stabilizing EGFR in Lung Adenocarcinoma

PURPOSE

Radioresistance is a major cause of treatment failure in tumor radiotherapy and the underlying mechanisms of radioresistance are still elusive. Golgi phosphoprotein 3 (GOLPH3) has been reported to associate tightly with cancer progression and chemoresistance. Herein, we explored whether GOLPH3 mediated radioresistance of lung adenocarcinoma (LUAD) and whether targeted suppression of GOLPH3 sensitized LUAD to radiotherapy.

METHODS AND MATERIALS

The aberrant expression of GOLPH3 was evaluated by immunohistochemistry in LUAD clinical samples. To evaluate the association between GOLPH3 and radioresistance, colony formation and apoptosis were assessed in control and GOLPH3 knockdown cells. γ-H2AX foci/level determination and micronucleus test were used to analyze DNA damage production and repair. The rescue of GOLPH3 knockdown was then performed by exogenous expression of siRNA-resistant mutant GOLPH3 to confirm the role of GOLPH3 in DNA damage repair. Mechanistically, the effect of GOLPH3 on regulating stability and nuclear accumulation of epidermal growth factor receptor (EGFR) and the activation of DNA-PK were investigated by qRT-PCR, western blot, immunofluorescence and co-immunoprecipitation. The role of GOLPH3 in vivo in radioresistance was determined in a xenograft model.

RESULTS

In tumor tissues of 33 patients with LUAD, the expression of GOLPH3 showed significantly increases compared with those in matched normal tissues. Knocking down GOLPH3 reduced the clonogenic capacity, impaired DSB repair and enhanced apoptosis after irradiation. In contrast, reversal of GOLPH3 depletion rescued the impaired repair of radiation-induced DSBs. Mechanistically, loss of GOLPH3 accelerated the degradation of EGFR in lysosome, causing the reduction in EGFR levels, thereby weakening nuclear accumulation of EGFR and attenuating the activation of DNA-PK. Furthermore, adenovirus-mediated GOLPH3 knockdown could enhance the ionizing-radiation response in LUAD xenograft model.

CONCLUSIONS

GOLPH3 conferred resistance of LUAD to ionizing-radiation via stabilizing EGFR and targeted suppression of GOLPH3 might be considered as a potential therapeutic strategy for sensitizing LUAD to radiotherapy.

Network Pharmacology-Based Mechanistic Investigation of Jinshui Huanxian Formula Acting on Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic respiratory disease with high incidence, morbidity, and mortality rates. Jinshui Huanxian formula (JHF) is an empirical formula that targets the pathogenesis of lung-kidney qi deficiency and phlegm-blood stasis in pulmonary fibrosis (PF). The purpose of this study was to explore JHF's potential pharmacological mechanisms in IPF therapy using network intersection analysis. JHF's primary active components and corresponding target genes were predicted using various databases. Two sets of IPF disease genes were obtained from the DisGeNET and GEO databases and two sets of IPF drug targets were collected. The disease and drug target genes were analyzed. The JHF target genes that intersected with IPF's differentially expressed genes were identified to predict JHF's targets of action in IPF. The functions and pathways of predicted targets acting on IPF were analyzed using the DAVID and KEGG pathway databases. Finally, the resulting drug target mechanisms were validated in a rat model of PF. The initial analyses identified 494 active compounds and 1,304 corresponding targets for JHF. The intersection analysis revealed four common genes for the JHF targets, IPF disease, and anti-IPF drugs in the KEGG database. Furthermore, these genes were targeted by several JHF compounds. Seventy-two JHF targets were closely related to IPF, which suggests that they are therapeutically relevant. Target screening revealed that they regulate IPF through 18 pathways. The targets' molecular functions included regulation of oxidoreductase activity, kinase regulator activity, phosphotransferase activity, and transmembrane receptor protein kinase activity. In vivo experiments showed that JHF alleviated the degree of PF, including decreases in collagen deposition and epithelial-mesenchymal transition. This study systematically explored JHF's mechanisms to identify the specific target pathways involved in IPF. The generated pharmacological network, paired with in vivo validation, elucidates the potential roles and mechanisms of JHF in IPF therapy.

Sunitinib-Loaded Chondroitin Sulfate Hydrogels as a Novel Drug-Delivery Mechanism for the Treatment of Pancreatic Neuroendocrine Tumors

BACKGROUND

Pancreatic neuroendocrine tumors (PanNETs) are increasingly common. Experts debate whether small tumors should be resected. Tumor destruction via injection of cytotoxic agents could offer a minimal invasive approach to this controversy. We hypothesize that a new drug delivery system comprising chondroitin sulfate (CS) hydrogels loaded with sunitinib (SUN) suppresses tumor growth in PanNET cells.

METHODS

Injectable hydrogels composed of CS modified with methacrylate groups (MA) were fabricated and loaded with SUN. Loading target was either 200 µg (SUN200-G) or 500 µg (SUN500-G) as well as sham hydrogel with no drug loading (SUN0-G). SUN release from hydrogels was monitored in vitro over time and cytotoxicity induced by the released SUN was evaluated using QGP-1 and BON1 PanNET cell lines. QGP-1 xenografts were developed in 35 mice and directly injected with 25 µL of either SUN200-G, SUN500-G, SUN0-G, 100 µL of Sunitinib Malate (SUN-inj), or given 40 mg/kg/day oral sunitinib (SUN-oral).

RESULTS

SUN-loaded CSMA hydrogel retained complete in vitro cytotoxicity toward the QGP-1 PanNET and BON-1 PanNET cell lines for 21 days. Mouse xenograft models with QGP-1 PanNETs showed a significant delay in tumor growth in the SUN200/500-G, SUN-inj and SUN-oral groups compared with SUN0-G (p = 0.0014). SUN500-G hydrogels induced significantly more tumor necrosis than SUN0-G (p = 0.04). There was no difference in tumor growth delay between SUN200/500G, SUN-inj, and SUN-oral.

CONCLUSIONS

This study demonstrates that CSMA hydrogels loaded with SUN suppress PanNETs growth. This drug delivery could approach represents a novel way to treat PanNETs and other neoplasms via intratumoral injection.

Targeted Therapies in the Management of Well-Differentiated Digestive and Lung Neuroendocrine Neoplasms

OPINION STATEMENT

Ongoing advances in our understanding of neuroendocrine tumor (NET) biology, genetics, and immunology, will continue to expand the availability of targeted therapies, thus improving the outcomes of patients. Well-differentiated neuroendocrine tumors (NETs) are grouped into pancreatic and non-pancreatic NETs (includes GI and thoracic NETs) for treatment considerations (Fig. 1). For panNETs, initial therapy is driven by the need of radiographic response, and targeted agents are typically reserved for second and third line based on the toxicity profile. Treatment options for non-pancreatic NETs are also expanding and while SSAs are the typical first-line option, everolimus and PRRT both remain approved therapies for future lines, and VEGF TKIs are showing promising results in research settings. Sequencing these agents and best time to incorporate peptide receptor radio therapy into the management algorithm remains an unmet need.

Association between vascular endothelial growth factor receptor 2 rs11941492 C/T polymorphism and Chinese Han patients in rheumatoid arthritis

The aim of the present study was to examine the association between vascular endothelial growth factor receptor 2 (VEGFR2) rs11941492 C/T polymorphism and rheumatoid arthritis (RA) risk in an eastern Chinese Han population. We examined VEGFR2 rs11941492 C/T polymorphism in 615 RA patients and 839 controls in an East Chinese Han population. The power analysis was used for evaluating the reliability of the results. Genotyping was performed using a custom-by-design 48-Plex single nucleotide polymorphism scan Kit. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using logistic regression.Our results indicated that VEGFR2 rs11941492 C/T polymorphism (TT vs CC, P = .012, OR = 0.61, 95% CI = 0.41-0.89; TT vs CT + CC, P = .017, OR = 0.63, 95% CI = 0.43-0.92) was associated with a significantly decreased risk of RA. The power analysis showed that this study had a power of 98.5% to detect the effect of rs11941492 C/T polymorphism on RA susceptibility, assuming an OR of 0.61. After stratification analysis, a decreased risk of RA was associated with VEGFR2 rs11941492 TT genotype (TT vs CC) among female patients (TT vs CC, P = .007, OR = 0.53, 95% CI = 0.33-0.84), older patients (Yr ≥55) (TT vs CC, P = .039, OR = 0.58, 95% CI = 0.35-0.97), C-reactive protein-positive patients, anti-cyclic citrullinated peptide antibody-negative patients, rheumatoid factor-positive patients (TT vs CT + CC, P = .015, OR = 0.60, 95% CI = 0.39-0.90), functional class III + IV patients, patients with a DAS28 of ≥3.20, and those with an erythrocyte sedimentation rate of <25. However, our results were obtained from only a moderate-sized sample. Studies with larger sample sizes in other ethnic populations are needed to confirm these results. The VEGFR2 rs11941492 genotype is associated with decreased susceptibility to RA.

Novel human Ab against vascular endothelial growth factor receptor 2 shows therapeutic potential for leukemia and prostate cancer

Vascular endothelial growth factor receptor 2 (VEGFR2) is highly expressed in tumor‐associated endothelial cells, where it modulates tumor‐promoting angiogenesis, and it is also found on the surface of tumor cells. Currently, there are no Ab therapeutics targeting VEGFR2 approved for the treatment of prostate cancer or leukemia. Therefore, development of novel efficacious anti‐VEGFR2 Abs will benefit cancer patients. We used the Institute of Cellular and Organismic Biology human Ab library and affinity maturation to develop a fully human Ab, anti‐VEGFR2‐AF, which shows excellent VEGFR2 binding activity. Anti‐VEGFR2‐AF bound Ig‐like domain 3 of VEGFR2 extracellular region to disrupt the interaction between VEGF‐A and VEGFR2, neutralizing downstream signaling of the receptor. Moreover, anti‐VEGFR2‐AF inhibited capillary structure formation and exerted Ab‐dependent cell‐mediated cytotoxicity and complement‐dependent cytotoxicity in vitro. We found that VEGFR2 is expressed in PC‐3 human prostate cancer cell line and associated with malignancy and metastasis of human prostate cancer. In a PC‐3 xenograft mouse model, treatment with anti‐VEGFR2‐AF repressed tumor growth and angiogenesis as effectively and safely as US FDA‐approved anti‐VEGFR2 therapeutic, ramucirumab. We also report for the first time that addition of anti‐VEGFR2 Ab can enhance the efficacy of docetaxel in the treatment of a prostate cancer mouse model. In HL‐60 human leukemia‐xenografted mice, anti‐VEGFR2‐AF showed better efficacy than ramucirumab with prolonged survival and reduced metastasis of leukemia cells to ovaries and lymph nodes. Our findings suggest that anti‐VEGFR2‐AF has strong potential as a cancer therapy that could directly target VEGFR2‐expressing tumor cells in addition to its anti‐angiogenic action.

Suppression of migratory and metastatic pathways via blocking VEGFR1 and VEGFR2

BACKGROUND

Vascular endothelial growth factor (VEGF) A and B are endothelial cell mitogens whose ligation to VEGFR1/VEGFR2 drives tumor angiogenesis and metastasis, and epithelial-mesenchymal transition (EMT). Blockade of these signaling axes could be obtained by disturbing the interactions between VEGFA and/or VEGFB with VEGFR1 and/or VEGFR2.

METHODS

A 14-mer peptide (VGB) that recognizes both VEGFR1 and VEGFR2 were investigated for its inhibitory effects on the VEGF-induced proliferation and migration using MTT and scratch assay, respectively. Downstream signaling pathways were also assessed by quantitative estimation of gene and protein expression using real-time PCR and immunohistochemistry (IHC).

RESULTS

We investigated the inhibitory effects of VGB on downstream mediators of metastasis, including epithelial-cadherin (E-cadherin), matrix metalloprotease-9 (MMP-9), cancer myelocytomatosis (c-Myc), and nuclear factor-κβ (NF-κβ), and migration, comprising focal adhesion kinase (FAK) and its substrate Paxilin. VGB inhibited the VEGF-induced proliferation of human umbilical vein endothelial cells (HUVECs), 4T1 and U87 cells in a time- and dose-dependent manner and migration of HUVECs. Based on IHC analyses, treatment of 4T1 mammary carcinoma tumor with VGB led to the suppression of p-AKT, p-ERK_1/2, MMP-9, NF-κβ, and activation of E-cadherin compared with PBS-treated controls. Moreover, quantitative real-time PCR analyses of VGB-treated tumors revealed the reduced expression level of FAK, Paxilin, NF-κβ, MMP-9, c-Myc, and increased expression level of E-cadherin compared to PBS-treated controls.

CONCLUSIONS

Our results demonstrated that simultaneous blockade of VEGFR1/VEGFR2 is an effective strategy to fight solid tumors by targeting a wider range of mediators involved in tumor angiogenesis, growth, and metastasis.

UCHL1 loss alters the cell-cycle in metastatic pancreatic neuroendocrine tumors

Loss of ubiquitin carboxyl-terminal hydrolase L1 (UCHL1) expression by CpG promoter hypermethylation is associated with metastasis in gastroenteropancreatic neuroendocrine tumors; however, the mechanism of how UCHL1 loss contributes to metastatic potential remains unclear. In this study, we first confirmed that loss of UCHL1 expression on immunohistochemistry was significantly associated with metastatic tumors in a translational pancreatic neuroendocrine tumor (PNET) cohort, with a sensitivity and specificity of 78% and 89%, respectively. To study the mechanism driving this aggressive phenotype, BON and QGP-1 metastatic PNET cell lines, which do not produce UCHL1, were stably transfected to re-express UCHL1. In vitro assays, RNA-sequencing, and reverse-phase protein array (RPPA) analyses were performed comparing empty-vector negative controls and UCHL1-expressing cell lines. UCHL1 re-expression is associated with lower anchorage-independent colony growth in BON cells, lower colony formation in QGP cells, and a higher percentage of cells in the G0/G1 cell-cycle phase in BON and QGP cells. On RPPA proteomic analysis, there was an upregulation of cell-cycle regulatory proteins CHK2 (1.2 fold change, p=0.004) and P21 (1.2 fold change, p=0.023) in BON cells expressing UCHL1; western blot confirmed upregulation of phosphorylated CHK2 and P21. There were no transcriptomic differences detected on RNA-Sequencing between empty-vector negative controls and UCHL1-expressing cell lines. In conclusion, UCHL1 loss correlates with metastatic potential in PNETs and its re-expression induces a less aggressive phenotype in vitro, in part by inducing cell-cycle arrest through post-translational regulation of phosphorylated CHK2. UCHL1 re-expression should be considered as a functional biomarker in detecting PNETs capable of metastasis.

Transient expression of anti-VEFGR2 nanobody in Nicotiana tabacum and N. benthamiana

In human, the interaction between vascular endothelial growth factor (VEGF) and its receptor (VEGFR2) is critical for tumor angiogenesis. This is a vital process for cancer tumor growth and metastasis. Blocking VEGF/VEGFR2 conjugation by antibodies inhibits the neovascularization and tumor metastasis. This investigation designed to use a transient expression platform for production of recombinant anti-VEGFR2 nanobody in tobacco plants. At first, anti-VEGFR2-specific nanobody gene was cloned in a Turnip mosaic virus (TuMV)-based vector, and then, it was expressed in Nicotiana benthamiana and Nicotiana tabacum cv. Xanthi transiently. The expression of nanobody in tobacco plants were confirmed by reverse transcription-polymerase chain reaction (RT-PCR), dot blot, enzyme-linked immunosorbent assays (ELISA), and Western blot analysis. It was shown that tobacco plants could accumulate nanobody up to level 0.45% of total soluble protein (8.3 µg/100 mg of fresh leaf). This is the first report of the successful expression of the camelied anti-VEFGR2 nanobody gene in tobacco plants using a plant viral vector. This system provides a fast solution for production of pharmaceutical and commercial proteins such as anti-cancer nanobodies in tobacco plants.

Elucidating the gene regulatory networks modulating cancer stem cells and non-stem cancer cells in high grade serous ovarian cancer

The origin and pathogenesis of epithelial ovarian cancer have perplexed investigators for decades. The most prevalent type of it is the high-grade serous ovarian carcinoma (HGSOv) which is a highly aggressive disease with high relapse rates and insurgence of chemo-resistance at later stages of treatment. These are driven by a rare population of stem cell like cancer cells called cancer stem cells (CSCs). We have taken up a systems approach to find out the common gene interaction paths between non-CSC tumor cells (CCs) and CSCs in HGSOv. Detailed investigation reveals a set of 17 Transcription Factors (named as pivot-TFs) which can govern changes in the mode of gene regulation along these paths. Overall, this work highlights a divergent road map of functional information relayed by these common key players in the two cell states, which might aid towards designing novel therapeutic measures to target the CSCs for ovarian cancer therapy.

PTEN Inhibition in Human Disease Therapy

The tumor suppressor PTEN is a major homeostatic regulator, by virtue of its lipid phosphatase activity against phosphatidylinositol 3,4,5-trisphosphate [PI(3,4,5)P3], which downregulates the PI3K/AKT/mTOR prosurvival signaling, as well as by its protein phosphatase activity towards specific protein targets. PTEN catalytic activity is crucial to control cell growth under physiologic and pathologic situations, and it impacts not only in preventing tumor cell survival and proliferation, but also in restraining several cellular regeneration processes, such as those associated with nerve injury recovery, cardiac ischemia, or wound healing. In these conditions, inhibition of PTEN catalysis is being explored as a potentially beneficial therapeutic intervention. Here, an overview of human diseases and conditions in which PTEN inhibition could be beneficial is presented, together with an update on the current status of specific small molecule inhibitors of PTEN enzymatic activity, their use in experimental models, and their limitations as research or therapeutic drugs.

A Novel Fusion Antibody Exhibits Antiangiogenic Activity and Stimulates NK Cell-mediated Immune Surveillance Through Fused NKG2D Ligand

A single-chain variable fragment (scFv) targeting vascular endothelial growth factor receptor 2 was previously generated from a phage display library in our laboratory. However, it has shortened half-life and lacks Fc fragment for effector cell recognition. To address these challenges, a ligand of NK-cell receptor NKG2D was fused to the scFv and created a fusion protein scFv-major histocompatibility complex class I-related chain A (MICA), which is expected to recognize tumor cells through the scFv moiety and stimulate NK cells through the MICA. The fusion protein demonstrated specific binding to both vascular endothelial growth factor receptor 2 and NKG2D in protein-based and cell-based assays. In addition, it demonstrated antiangiogenic activities including restraining the proliferation, migration, transwell invasion, and tube formation of human umbilical vein endothelial cells. Furthermore, the fusion protein exhibited significant cytotoxicity on K562, MDA-MB-435, and B16F10 cells and triggered NK92 cell-mediated cytotoxicity on MDA-MB-435 cells by stimulating the release of significant cytokines. The fusion protein targeting strategy, therefore, provides a means to engage lymphocyte effector cells against tumor specific antigen overexpressing tumor cells.

Multi-physics interactions drive VEGFR2 relocation on endothelial cells

Vascular Endothelial Growth Factor Receptor-2 (VEGFR2) is a pro-angiogenic receptor, expressed on endothelial cells (ECs). Although biochemical pathways that follow the VEGFR2 activation are well established, knowledge about the dynamics of receptors on the plasma membrane remains limited. Ligand stimulation induces the polarization of ECs and the relocation of VEGFR2, either in cell protrusions or in the basal aspect in cells plated on ligand-enriched extracellular matrix (ECM). We develop a mathematical model in order to simulate the relocation of VEGFR2 on the cell membrane during the mechanical adhesion of cells onto a ligand-enriched substrate. Co-designing the in vitro experiments with the simulations allows identifying three phases of the receptor dynamics, which are controlled respectively by the high chemical reaction rate, by the mechanical deformation rate, and by the diffusion of free receptors on the membrane. The identification of the laws that regulate receptor polarization opens new perspectives toward developing innovative anti-angiogenic strategies through the modulation of EC activation.

Metformin incombination with curcumin inhibits the growth, metastasis, and angiogenesis of hepatocellular carcinoma in vitro and in vivo

Hepatocellular carcinoma (HCC) has poor prognosis due to the advanced disease stages by the time it is diagnosed, high recurrence rates and metastasis. In the present study, we investigated the effects of metformin (a safe anti-diabetic drug) and curcumin (a turmeric polyphenol extracted from rhizome of Curcuma longa Linn.) on proliferation, apoptosis, invasion, metastasis, and angiogenesis of HCC in vitro and in vivo. It was found that co-treatment of metformin and curcumin could not only induce tumor cells into apoptosis through activating the mitochondria pathways, but also suppress the invasion, metastasis of HCC cells and angiogenesis of HUVECs. These effects were associated with downregulation of the expression of MMP2/9, VEGF, and VEGFR-2, up-regulation of PTEN, P53 and suppression of PI3K/Akt/mTOR/NF-κB and EGFR/STAT3 signaling. Co-administration of metformin and curcumin significantly inhibited HCC tumor growth than administration with metformin or curcumin alone in a xenograft mouse model. Thus, metformin and curcumin in combination showed a better anti-tumor effects in hepatoma cells than either metformin or curcumin presence alone and might represent an effective therapeutic strategy for HCC treatment.

VEGFR2 regulates endothelial differentiation of colon cancer cells

Background

Recent studies suggested that cancer stem-like cells contribute to tumor vasculogenesis by differentiating into endothelial cells. However, such process is governed by still undefined mechanism.

Methods

At varying differentiation levels, three representative colon cancer cells were cultured in endothelial-inducing conditioned medium: human colon cancer cells HCT116 (HCT116) (poorly differentiated), SW480 (moderately differentiated), and HT29 (well differentiated). We tested for expression of endothelial markers (cluster of differentiation (CD) 31, CD34, and vascular endothelial (VE)-cadherin and their ability to form tube-like structures in 3D culture. We also observed VEGF secretion and expressions of endothelial markers and VEGFRs in HCT116 cells under hypoxia to simulate physiological conditions. In in vitro and in xenotransplantation experiments, VE growth factor receptor 2 (VEGFR2) antagonist SKLB1002 was used to test effect of VEGFR2 in endothelial differentiation of HCT116 cells. Expression levels of VEGFR2 and VE-cadherin were assessed by immunohistochemistry of human colon cancer tissues to evaluate clinicopathological significance of VEGFR2.

Results

After culturing in endothelial-inducing conditioned medium, poorly differentiated HCT116 cells expressed endothelial markers and formed tube-like structure in vitro. HCT116 cells secreted more endogenous VEGF and expressed higher VEGFR2 under hypoxia. SKLB1002 impaired endothelial differentiation in vitro and xenotransplantation experiments, suggesting a VEGFR2-dependent mechanism. Increased expression of VEGFR2 correlated with differentiation, metastasis/recurrence, and poor prognosis in 203 human colon cancer samples. Positive correlation was observed between VEGFR2 and VE-cadherin expression.

Conclusions

VEGFR2 regulates endothelial differentiation of colon cancer cell and may be potential platform for anti-angiogenesis cancer therapy.

Glioma cell VEGFR-2 confers resistance to chemotherapeutic and antiangiogenic treatments in PTEN-deficient glioblastoma

Loss of the tumor suppressor phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a prerequisite for tumor cell-specific expression of vascular endothelial growth factor receptor (VEGFR)-2 in glioblastoma defining a subgroup prone to develop evasive resistance towards antiangiogenic treatments. Immunohistochemical analysis of human tumor tissues showed VEGFR-2 expression in glioma cells in 19% of specimens examined, mainly in the infiltration zone. Glioma cell VEGFR-2 positivity was restricted to PTEN-deficient tumor specimens. PTEN overexpression reduced VEGFR-2 expression in vitro, as well as knock-down of raptor or rictor. Genetic interference with VEGFR-2 revealed proproliferative, antiinvasive and chemoprotective functions for VEGFR-2 in glioma cells. VEGFR-2-dependent cellular effects were concomitant with activation of 'kappa-light-chain-enhancer' of activated B-cells, protein kinase B, and N-myc downstream regulated gene 1. Two-photon in vivo microscopy revealed that expression of VEGFR-2 in glioma cells hampers antiangiogenesis. Bevacizumab induces a proinvasive response in VEGFR-2-positive glioma cells. Patients with PTEN-negative glioblastomas had a shorter survival after initiation of bevacizumab therapy compared with PTEN-positive glioblastomas. Conclusively, expression of VEGFR-2 in glioma cells indicates an aggressive glioblastoma subgroup developing early resistance to temozolomide or bevacizumab. Loss of PTEN may serve as a biomarker identifying those tumors upfront by routine neuropathological methods.

Glutamine Synthetase Immunoreactivity in Peritumoral Hyperplasia in Liver: Case Report of a Metastatic Paraganglioma With Focal Nodular Hyperplasia-Like Changes and Review of an Additional 54 Liver Masses

OBJECTIVES

Focal nodular hyperplasia (FNH) and peritumoral hyperplasia in the liver exhibit increased immunoreactivity for glutamine synthetase (GS). We observed FNH-like changes with map-like GS staining surrounding a metastatic paraganglioma and sought to determine how often such changes occur around primary and metastatic liver lesions.

METHODS

We performed GS immunohistochemistry in liver cases of 20 metastatic neuroendocrine carcinomas (NECs), 21 metastatic colon carcinomas (CCs), seven hepatocellular carcinomas (HCCs), and six FNHs and assessed lesions for size, degree of fibrosis (scored 1-3), and peritumoral hyperplasia.

RESULTS

Most NEC or CC cases had few peritumoral hyperplastic features. Three NECs, two CCs, and one HCC (13%) had patchy GS staining at the periphery of the lesions. One CC case had both histologic and immunohistochemical peritumoral hyperplasia.

CONCLUSIONS

Peritumoral hyperplasia or FNH-like changes are uncommon findings around primary or metastatic lesions in the liver. GS immunohistochemistry assists in distinguishing true peritumoral hyperplasia from mass effect.

Role of targeted agents in neuroendocrine tumors: Results from a meta-analysis

BACKGROUND

Several randomized phase III trials in neuroendocrine tumors (NETs) showed the clinical role of new targeted agents and their impact on tumor response and outcome of whose patients affected by advanced NET. In this study, we summarize the available clinical data related to clinical efficacy of targeted therapies in the treatment of advanced NETs.

METHODS

A meta-analysis of randomized studies in accordance with the PRISMA guidelines was performed after searching the databases of PubMed, the Cochrane Library, and the ASCO University Meeting for relevant publications.

RESULTS

One thousand 9 hundred and 8 cases were included in the meta-analysis; among these, 1012 were in the experimental arm and 896 were in the control arm. The pooled analysis of the use of target agents in NETs revealed significantly increased of progression free survival compared to control group (hazard ratio = 0.59, 95% CI:0.42-0.84; P = 0.003). Subgroup analysis of patients according to tumor site showed a difference in favor of pancreatic neuroendocrine tumors. Moreover, targeted therapies improved the overall survival (hazard ratio = 0.79, 95%CI: 0.63-0.98; P = 0.03), and response rate (hazard ratio = 3.33, 95% CI 2.02-5.49; P < 0.00001) in all types of NETs.

CONCLUSION

Our analysis supports the routine use of targeted agents for treatment of neuroendocrine tumors with particular regards to the pancreatic neuroendocrine tumors.

Suppression of mTOR pathway in solid tumors: lessons learned from clinical experience in renal cell carcinoma and neuroendocrine tumors and new perspectives

The PI3K-AKT-mTOR pathway plays role in the regulation of many cellular processes. Hyperactivation of mTOR signaling has been implicated in human carcinogenesis, representing an attractive target for cancer therapy. Among other cancer subtypes, renal cell carcinoma (RCC) and neuroendocrine tumors are relevant settings in which the deregulation of mTOR pathway is of crucial importance. Different mTOR-inhibitory agents have been developed in recent years. Temsirolimus is approved for advanced RCC; everolimus is registered for the treatment of advanced RCC, pancreatic neuroendocrine tumors and postmenopausal, hormone receptor-positive/HER2-negative, advanced breast cancer. This review is focused on the description of the clinical experience with mTOR-inhibitor agents for the treatment of advanced RCC and neuroendocrine tumors, followed by an excursus on the landscape of the ongoing research in this field.

Pulmonary atypical carcinoid in a patient with Cowden syndrome

Cowden syndrome is a phosphatase and tensin homologue on chromosome ten (PTEN) hamartoma tumour syndrome. The loss of function of the PTEN protein is associated with the risk of development and progression of several types of tumours, such as pulmonary neuroendocrine tumours and carcinoids. We present a 65-year old male non-smoker, who was diagnosed with Cowden syndrome and had a pulmonary tumour. He underwent wedge resection via video-assisted thoracoscopic surgery and was histopathologically diagnosed with an atypical carcinoid. To our knowledge, this is the first report on a pulmonary atypical carcinoid in a patient with Cowden syndrome. The present findings suggest a potential link between phosphoinositide-3 kinase/protein kinase B signalling in Cowden syndrome and the development of pulmonary neuroendocrine tumours, such as carcinoids.

Peroxiredoxin II Is Essential for Maintaining Stemness by Redox Regulation in Liver Cancer Cells

Redox regulation in cancer stem cells (CSCs) is viewed as a good target for cancer therapy because redox status plays an important role in cancer stem-cell maintenance. Here, we investigated the role of Peroxiredoxin II (Prx II), an antioxidant enzyme, in association with maintenance of liver CSCs. Our study demonstrates that Prx II overexpressed in liver cancer cells has high potential for self-renewal activity. Prx II expression significantly corelated with expression of epithelial-cell adhesion molecules (EpCAM) and cytokerain 19 in liver cancer tissues of hepatocellular carcinoma (HCC) patients. Downregulation of Prx II in Huh7 cells with treatment of siRNA reduced expression of EpCAM and CD133 as well as Sox2 in accordance with increased ROS and apoptosis, which were reversed in Huh7-hPrx II cells. Huh7-hPrx II cells exhibited strong sphere-formation activity compared with mock cells. Vascular endothelial growth factor (VEGF) exposure enhanced sphere formation, cell-surface expression of EpCAM and CD133, and pSTAT3 along with activation of VEGF receptor 2 in Huh7-hPrx II cells. The result also emerged in Huh7-H-ras(G12V) and SK-HEP-1-H-ras(G12V) cells with high-level expression of Prx II. Prx II was involved in regulation of VEGF driving cancer stem cells through VEGFR-2/STAT3 signaling to upregulate Bmi1 and Sox2. In addition, knockdown of Prx II in Huh7-H-ras(G12V) cells showed significant reduction in cell migration in vitro and in tumorigenic potential in vivo. Taken together, all the results demonstrated that Prx II plays a key role in the CSC self-renewal of HCC cells through redox regulation. Stem Cells 2016;34:1188-1197.

Medical Management of Pancreatic Neuroendocrine Tumors: Current and Future Therapy

When diagnosed at an early stage, resection of pancreatic neuroendocrine tumors (NETs) is often curative. Unfortunately, curative surgery is rarely an option for patients with metastatic disease. Multiple options are available for the management of patients with advanced pancreatic NETs, including surgery, liver-directed therapy, and systemic therapies. Because of the heterogeneity of disease biology and presentation, a multidisciplinary approach to management is critical. Treatment with somatostatin analogs, sunitinib, everolimus, and alkylating agents provide effective systemic therapeutic options for patients. Future studies to evaluate the optimal timing, sequence, and combination of therapies, as well as to identify predictors of response, are warranted.

Correlation between VEGFR2 rs2071559 polymorphism and glioma risk among Chinese population

OBJECTIVE

We investigated the correlation between vascular endothelial growth factor 2 (VEGFR2) polymorphism and glioma risk among Chinese population.

METHOD

Case-control study design was adopted, and blood samples and clinical data of 250 glioma cases and 260 control subjects were collected. Epidemiological questionnaire survey was performed, and DNA extraction, concentration normalization and packaging were carried out using Qiagen Blood Kit. TaqMan method was performed for VEGFR2 rs2071559 genotyping.

RESULTS

C allele of VEGFR2 rs2071559 genotype was the susceptibility allele contributing to the risk of glioma (OR=1.813, 95% CI: 1.393-2.359, P=0.014). CC genotypes of VEGFR2 rs2071559 were associated with increased risk of glioma (OR=2.068, 95% CI: 1.164-3.674, P=0.014; Adjusted OR=1.883, 95% CI: 1.430~3.013, P=0.018).

CONCLUSION

CC genotypes of VEGFR2 rs2071559 were associated with glioma risk among Chinese population. However, the role of VEGFR2 rs2071559 polymorphism in glioma susceptibility remains to be further clarified.

Vascular endothelial growth factor directly stimulates tumour cell proliferation in non-small cell lung cancer

Vascular endothelial growth factor (VEGF) is a key stimulator of physiological and pathological angiogenesis. VEGF signals primarily through VEGF receptor 2 (VEGFR2), a receptor tyrosine kinase whose expression is found predominantly on endothelial cells. The purpose of this study was to determine the role of VEGFR2 expression in NSCLC cells. NSCLC cells and tissue sections were stained for VEGFR2 expression by immunohistochemistry (IHC). Immunoblotting and ELISA were used to determine the activation and inhibition of VEGFR2 and its downstream signalling pathways. Five-day proliferation assays were carried out in the presence or absence of VEGF. IHC analysis of NSCLC demonstrated tumour cell VEGFR2 expression in 20% of samples. Immunoblot analysis showed expression of VEGFR2 protein in 3/8 NSCLC cell lines that correlated with VEGFR2 mRNA expression levels. VEGF-dependent VEGFR2 activation was apparent in NSCLC cells, and was associated with increased tumor cell proliferation. Cediranib treatment or siRNA against VEGFR2 inhibited VEGF-dependent increases in cell proliferation. Inhibition of VEGFR2 tyrosine kinase activity using cediranib was more effective than inhibition of AKT (MK2206) or MEK (AZD6244) for overcoming VEGFR2-driven cell proliferation. VEGF treatment did not affect cell survival following treatment with radiation, cisplatin, docetaxel or gemcitabine. Our data suggest that a subset of NSCLC tumour cells express functional VEGFR2 which can act to promote VEGF-dependent tumour cell growth. In this tumour subset, therapies targeting VEGFR2 signalling, such as cediranib, have the potential to inhibit both tumour cell proliferation and angiogenesis.

Whole-exome characterization of pancreatic neuroendocrine tumor cell lines BON-1 and QGP-1

The human BON-1 and QGP-1 cell lines are two frequently used models in pancreatic neuroendocrine tumor (PNET) research. Data on the whole-exome genetic constitution of these cell lines is largely lacking. This study presents, to our knowledge, the first whole-exome profile of the BON-1 and QGP-1 cell lines. Cell line identity was confirmed by short tandem repeat profiling. Using GTG-banding and a CytoSNP-12v2 Beadchip array, cell line ploidy and chromosomal alterations were determined in BON-1 and QGP-1. The exomes of both cell lines were sequenced on Ilumina's HiSeq next-generation sequencing (NGS) platform. Single-nucleotide variants (SNVs) and insertions and deletions (indels) were detected using the Genome Analysis ToolKit. SNVs were validated by Sanger sequencing. Ploidy of BON-1 and QGP-1 was 3 and 4 respectively, with long stretches of loss of heterozygosity across multiple chromosomes, which is associated with aggressive tumor behavior. In BON-1, 57 frameshift indels and 1725 possible protein-altering SNVs were identified in the NGS data. In the QGP-1 cell line, 56 frameshift indels and 1095 SNVs were identified. ATRX, a PNET-associated gene, was mutated in both cell lines, while mutation of TSC2 was detected in BON-1. A mutation in NRAS was detected in BON-1, while KRAS was mutated in QGP-1, implicating aberrations in the RAS pathway in both cell lines. Homozygous mutations in TP53 with possible loss of function were identified in both cell lines. Various MUC genes, implicated in cell signaling, lubrication and chemical barriers, which are frequently expressed in PNET tissue samples, showed homozygous protein-altering SNVs in the BON-1 and QGP-1 cell lines.

Activation of the NF-κB pathway as a mechanism of alcohol enhanced progression and metastasis of human hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC), the most common form of primary liver cancer, is the third leading cause of cancer-related death in human. Alcohol is a known risk factor for HCC. However it is still unclear whether and how alcohol enhances the progression and metastasis of existing HCC.

METHODS AND RESULTS

We first retrospectively investigated 52 HCC patients (24 alcohol-drinkers and 28 non-drinkers), and found a positive correlation between alcohol consumption and advanced Tumor-Node-Metastasis (TNM) stages, higher vessel invasion and poorer prognosis. In vitro and in vivo experiments further indicated that alcohol promoted the progression and migration/invasion of HCC. Specifically, in a 3-D tumor/endothelial co-culture system, we found that alcohol enhanced the migration/invasion of HepG2 cells and increased tumor angiogenesis. Consistently, higher expression of VEGF, MCP-1 and NF-κB was observed in HCC tissues of alcohol-drinkers. Alcohol induced the accumulation of intracellular reactive oxygen species (ROS) and the activation of NF-κB signaling in HepG2 cells. Conversely, blockage of alcohol-mediated ROS accumulation and NF-κB signaling inhibited alcohol-induced expression of VEGF and MCP-1, the tumor growth, angiogenesis and metastasis.

CONCLUSION

This study suggested that chronic moderate alcohol consumption may promote the progression and metastasis of HCC; the oncogenic effect may be at least partially mediated by the ROS accumulation and NF-ĸB-dependent VEGF and MCP-1 up-regulation.

The PI3K/Akt Pathway in Tumors of Endocrine Tissues

The phosphatidylinositol 3-kinase (PI3K)/Akt pathway is a key driver in carcinogenesis. Defects in this pathway in human cancer syndromes such as Cowden's disease and Multiple Endocrine Neoplasia result in tumors of endocrine tissues, highlighting its importance in these cancer types. This review explores the growing evidence from multiple animal and in vitro models and from analysis of human tumors for the involvement of this pathway in the following: thyroid carcinoma subtypes, parathyroid carcinoma, pituitary tumors, adrenocortical carcinoma, phaeochromocytoma, neuroblastoma, and gastroenteropancreatic neuroendocrine tumors. While data are not always consistent, immunohistochemistry performed on human tumor tissue has been used alongside other techniques to demonstrate Akt overactivation. We review active Akt as a potential prognostic marker and the PI3K pathway as a therapeutic target in endocrine neoplasia.

Clinicopathological and prognostic significance of overexpression of VEGF and VEGFR2 in gastric cancer

AIM: To investigate the differential expression of vascular endothelial growth factor (VEGF) and vascular endothelial growth factor receptor 2 (VEGFR2) in gastric cancer to understand possible roles that VEGF and VEGFR2 receptor play in the carcinogenesis, progression and prognosis of gastric cancer.

METHODS: The expression of VEGF and VEGFR2 was examined using immunohistochemistry on paraffin embedded tissue chips derived from 73 patients with gastric cancer (GC) and 63 adjacent normal tissues (ANT) from the same patients. Expression data were analyzed against patients' clinicopathological features and follow-up information.

RESULTS: The level of VEGFR2 in GC tissues was significantly higher than that in ANT (P = 0.025), but no significant difference was detected in the level of VEGF between GC and ANT (P = 0.275). In GC tissues, a positive correlation was found between expression levels of VEGF and VEGFR2 (r = 0.455). High expression of VEGF was significantly associated with lymph node metastasis (P = 0.004), distant metastasis (P = 0.019) and advanced clinical stage (P = 0.003). High expression of VEGFR2 was associated with sex (P = 0.049), lymph node metastasis (P < 0.001), distant metastasis (P = 0.007) and advanced clinical stage (P < 0.001). High levels of both VEGF and VEGFR2 were linked to poor prognosis in GC patients (P = 0.043 and P = 0.016, respectively). Cox multi-factor regression analyses demonstrated that clinical stage was an independent factor predicting overall survival of GC patients (P = 0.001).

CONCLUSION: Overexpression of VEGF and VEGFR2 may suggest late stage, metastasis, and poor prognosis in gastric cancer patients. VEGFR2 may play a role more important than VEGF in the regulation of angiogenesis in gastric cancer.

Vascular endothelial growth factor (VEGF) pathway and neuroendocrine neoplasms (NENs): prognostic and therapeutic considerations

Neuroendocrine neoplasms (NENs) consist of a large heterogeneous group of epithelial tumors with neuroendocrine differentiation, as proved by immune reactivity for neuroendocrine markers. From the very first studies of vascular endothelial growth factor (VEGF) pathway, VEGF has been considered an important prognostic marker in NENs. Consequently, a number of preclinical experiences and clinical trials have examined the efficacy of VEGF-targeted therapeutics in NENs. Bevacizumab and sorafenib were clinically tested in NENs and they showed modest activity, while on the other hand, they present significant toxicity problems. More interesting in gastroenteropancreatic (GEP)-NENs seems to be the demonstrated efficacy of sunitinib. Preclinical as well as clinical sunitinib data in this regard provide a new hope in that direction. The use of other novel VEGF-targeted agents like aflibercept as well as VEGFR-TKI is being investigated in a number of phase II studies; the results of which are greatly awaited. Additionally, the use of potential biomarkers to select patients for VEGF-targeted therapy may be considered for further clinical evaluation. Thus, this article reviews the basic science as well as clinical data of VEGF signaling in advanced NENs with special emphasis on the different VEGF-targeting agents tested previously in this disease and the future prospective in that field.

Targeting the mTOR signaling pathway in neuroendocrine tumors

OPINION STATEMENT

Neuroendocrine tumors (NETs) are a heterogeneous group of malignancies characterized by variable but most often indolent biologic behavior. Well-differentiated NETs can be broadly classified as either carcinoid or pancreatic NET. Although they have similar characteristics on routine histologic evaluation, the 2 tumor subtypes have different biology and respond differently to treatment, with most therapeutic agents demonstrating higher response rates in pancreatic NETs compared with carcinoid. Until recently, systemic treatment options for patients with advanced NETs were limited. However, improvements in our understanding of signaling pathways involved in the pathogenesis, growth, and spread of NETs have translated into an expansion of treatment options. Aberrant signaling through the mechanistic pathway of rapamycin (mTOR) pathway has been implicated in neuroendocrine tumorigenesis. Additionally, altered expression of mTOR pathway components has been observed in NETs and has been associated with clinical outcomes. Targeting the mTOR pathway has emerged as an effective treatment strategy in the management of advanced NETs. In a randomized, placebo-controlled study of patients with advanced pancreatic NET, treatment with the mTOR inhibitor everolimus was associated with improved progression-free survival (PFS). Largely based upon these data, everolimus has been approved in the United States and Europe for the treatment of patients with advanced pancreatic NET. The activity of everolimus remains under investigation in patients with carcinoid tumors. In a randomized study of patients with advanced carcinoid tumors associated with carcinoid syndrome, the addition of everolimus to octreotide was associated with improved PFS compared with octreotide. However, the results did not meet the prespecified level of statistical significance based on central review of radiographic imaging. Results from a randomized study examining the efficacy of everolimus in patients with nonfunctional gastrointestinal and lung NETs are awaited. In addition, further investigation is needed to determine whether primary tumor site or other clinical and molecular factors can impact response to mTOR inhibition. Although everolimus can slow tumor progression, significant tumor reduction is rarely obtained. Targeting multiple signaling pathways is a treatment strategy that may provide better tumor control and overcome resistance mechanisms involved with targeting a single pathway. Results of ongoing and future studies will provide important information regarding the added benefit of combining mTOR inhibitors with other targeted agents, such as VEGF pathway inhibitors, and cytotoxic chemotherapy in the treatment of advanced NETs.

Carcinoid heart disease: current understanding and future directions

Carcinoid tumors are rare and aggressive malignancies. A multitude of vasoactive agents are central to the systemic effects of these tumors. The additional burden of cardiac dysfunction heralds a steep decline in quality of life and survival. Unfortunately, by the time carcinoid syndrome surfaces clinically, the likelihood of cardiac involvement is 50%. Although medical therapies such as somatostatin analogues may provide some symptom relief, they offer no mortality benefit. On the other hand, referral to surgery following early detection has shown increased survival. The prompt recognition of this disease is therefore of the utmost importance.

Contrasting responses of non-small cell lung cancer to antiangiogenic therapies depend on histological subtype

The vascular endothelial growth factor (VEGF) pathway is a clinically validated antiangiogenic target for non-small cell lung cancer (NSCLC). However, some contradictory results have been reported on the biological effects of antiangiogenic drugs. In order to evaluate the efficacy of these drugs in NSCLC histological subtypes, we analyzed the anticancer effect of two anti-VEGFR2 therapies (sunitinib and DC101) in chemically induced mouse models and tumorgrafts of lung adenocarcinoma (ADC) and squamous cell carcinoma (SCC). Antiangiogenic treatments induced vascular trimming in both histological subtypes. In ADC tumors, vascular trimming was accompanied by tumor stabilization. In contrast, in SCC tumors, antiangiogenic therapy was associated with disease progression and induction of tumor proliferation. Moreover, in SCC, anti-VEGFR2 therapies increased the expression of stem cell markers such as aldehyde dehydrogenase 1A1, CD133, and CD15, independently of intratumoral hypoxia. In vitro studies with ADC cell lines revealed that antiangiogenic treatments reduced pAKT and pERK signaling and inhibited proliferation, while in SCC-derived cell lines the same treatments increased pAKT and pERK, and induced survival. In conclusion, this study evaluates for the first time the effect of antiangiogenic drugs in lung SCC murine models in vivo and sheds light on the contradictory results of antiangiogenic therapies in NSCLC.

Ab-initio and Conformational Analysis of a Potent VEGFR-2 Inhibitor: A Case Study on Motesanib

Vascular endothelial growth factor receptor-2 (VEGFR-2); a cell surface receptor for vascular endothelial growth factors, is a key pharmacological target involved in the cell proliferation/angiogenesis. It has been revealed that VEGFR-2 induces proliferation through activation of the extracellular signal-regulated kinases pathway. In this regard, targeting the VEGFR-2 has been considered as an efficient route to develop anti-tumor agents. Motesanib is a small-molecule antagonist of VEGFR-1, 2, and 3 (IC50s; 2 nM, 3 nM, 6 nM, respectively). It is an experimental drug candidate undergoing clinical trials against some types of cancer. In the present study, Motesanib (AMG 706) was evaluated in terms of its binding energies with individual amino acids of VEGFR-2 active site (amino acid decomposition analysis). For this purpose, functional B3LYP associated with split valence basis set using polarization functions (Def2-SVP) was used. Comparative conformational analysis of the ligand in optimized and crystallographic states revealed that Motesanib does not necessarily bind to the VEGFR-2 active site in its minimum energy conformer.

Delphinidin reduces cell proliferation and induces apoptosis of non-small-cell lung cancer cells by targeting EGFR/VEGFR2 signaling pathways

Epidermal growth factor receptor (EGFR) and vascular endothelial growth factor receptor 2 (VEGFR2) have emerged as two effective clinical targets for non-small-cell lung cancer (NSCLC). In the present study, we found that delphinidin, an anthocyanidin, present in pigmented fruits and vegetables, is a potent inhibitor of both EGFR and VEGFR2 in NSCLC cells that overexpress EGFR/VEGFR2. Using these cells, we next determined the effects of delphinidin on cell growth and apoptosis in vitro and on tumor growth and angiogenesis in vivo. Delphinidin (5-60 µM) treatment of NSCLC cells inhibited the activation of PI3K, and phosphorylation of AKT and MAPKs. Additionally, treatment of NSCLC cells with delphinidin resulted in inhibition of cell growth without having significant toxic effects on normal human bronchial epithelial cells. Specifically, treatment of NCI-H441 and SK-MES-1 cells with delphindin (5-60 µM) resulted in (i) cleavage of PARP protein, (ii) activation of caspase-3 and -9, (iii) downregulation of anti-apoptotic proteins (Bcl2, Bcl-xL and Mcl-1), (iv) upregulation of pro-apoptotic proteins (Bax and Bak), and (v) decreased expression of PCNA and cyclin D1. Furthermore, in athymic nude mice subcutaneously implanted with human NSCLC cells, delphinidin treatment caused a (i) significant inhibition of tumor growth, (ii) decrease in the expression of markers for cell proliferation (Ki67 and PCNA) and angiogenesis (CD31 and VEGF), and (iii) induction of apoptosis, when compared with control mice. Based on these observations, we suggest that delphinidin, alone or as an adjuvant to current therapies, could be used for the management of NSCLC, especially those that overexpress EGFR and VEGFR2.

Protein kinase B phosphorylation correlates with vascular endothelial growth factor A and microvessel density in gastric adenocarcinoma

OBJECTIVE

The signalling molecule protein kinase B (Akt) modulates many cellular processes. Phosphatidylinositol 3-kinase (PI3K)/Akt signalling pathways play important roles in tumour angiogenesis. The aim of this study was to determine the role of phosphorylated Akt (pAkt) in angiogenesis and its correlation with vascular endothelial growth factor (VEGF)-A in gastric adenocarcinoma.

METHODS

Tumour tissue and matched healthy gastric mucosa were obtained from patients undergoing surgical resection of gastric adenocarcinoma. Akt and pAkt were detected via Western blotting. VEGF-A, pAkt and CD34 were examined by immunohistochemistry.

RESULTS

Akt and pAkt protein levels were significantly higher in gastric cancer tissue than in normal tissue (n = 48 patients). Positive VEGF-A immunostaining was significantly associated with pAkt immunostaining. Microvessel density was correlated with both VEGF-A and pAkt positivity.

CONCLUSIONS

Phosphorylated Akt and VEGF-A are involved in angiogenesis of gastric adenocarcinoma, and Akt activation may contribute to angiogenesis via VEGF-A upregulation. The PI3K/Akt/VEGF signalling pathway may be involved in gastric adeno carcinoma.