Role of angiogenesis in urothelial bladder carcinoma

Landscape of targeted therapies for advanced urothelial carcinoma

Bladder cancer (BC) is the tenth most common malignancy globally. Urothelial carcinoma (UC) is a major type of BC, and advanced UC (aUC) is associated with poor clinical outcomes and limited survival rates. Current options for aUC treatment mainly include chemotherapy and immunotherapy. These options have moderate efficacy and modest impact on overall survival and thus highlight the need for novel therapeutic approaches. aUC patients harbor a high tumor mutation burden and abundant molecular alterations, which are the basis for targeted therapies. Erdafitinib is currently the only Food and Drug Administration (FDA)-approved targeted therapy for aUC. Many potential targeted therapeutics aiming at other molecular alterations are under investigation. This review summarizes the current understanding of molecular alterations associated with aUC targeted therapy. It also comprehensively discusses the related interventions for treatment in clinical research and the potential of using novel targeted drugs in combination therapy.

An Overview of Angiogenesis in Bladder Cancer

PURPOSE OF THE REVIEW

Angiogenesis plays a key role in bladder cancer (BC) pathogenesis. In the last two decades, an increasing number of publications depicting a multitude of novel angiogenic molecules and pathways have emerged. The growing complexity necessitates an evaluation of the breadth of current knowledge to highlight key findings and guide future research.

RECENT FINDINGS

Angiogenesis is a dynamic biologic process that is inherently difficult to assess. Clinical assessment of angiogenesis in BCs is advancing with the integration of image analysis systems and dynamic contrast-enhanced and magnetic resonance imaging (DCE-MRI). Tumour-associated macrophages (TAMs) significantly influence the angiogenic process, and further research is needed to assess their potential as therapeutic targets. A rapidly growing list of non-coding RNAs affect angiogenesis in BCs, partly through modulation of vascular endothelial growth factor (VEGF) activity. Vascular mimicry (VM) has been repeatedly associated with increased tumour aggressiveness in BCs. Standardised assays are needed for appropriate identification and quantification of VM channels. This article demonstrates the dynamic and complex nature of the angiogenic process and asserts the need for further studies to deepen our understanding.

An angiogenesis‑related lncRNA signature for the prognostic prediction of patients with bladder cancer and LINC02321 promotes bladder cancer progression via the VEGFA signaling pathway

The mechanism underlying bladder cancer metastasis is associated with tumor angiogenesis. The present study aimed to evaluate the predictive role and value of an angiogenesis‑associated long non‑coding (lnc)RNA signature in patients with bladder cancer and the role of long intergenic non‑coding RNA (LINC)02321 in the progression of this malignancy. Angiogenesis‑related lncRNAs were screened using Pearson correlation analysis and the signaturewas constructed using Cox regression analysis and evaluated using the receiver operating characteristic curve. LINC02321, which expressed the largest difference in bladder cancer, was screened using reverse transcription‑quantitative PCR. The role of LINC02321 in the malignant progression of bladder cancer was evaluated using Transwell, wound healing and Cell Counting Kit 8 assays. A total of six angiogenesis‑associated lncRNAs (USP30‑AS1, LINC02321, PSMB8‑AS1, KRT7‑AS, LINC01767 and OCIAD1‑AS1) were identified as candidates for the prognostic signature using Cox regression analysis. The overall survival of patients in the low‑risk group was significantly longer compared with that in the high‑risk group, with the highest area under the curve value being 0.807. A nomogram was constructed based on the traditional clinical indicators (age, sex, grade, American Joint Committee on Cancer stage) and risk score of patients. Compared with the traditional clinical indicators, the risk score demonstrated better clinical prediction capacity for predicting the prognosis of patients with bladder cancer. The Cancer Genome Atlas prediction and RT‑qPCR experimental results demonstrated that only LINC02321 was highly expressed in bladder cancer tissue and promoted the proliferation, invasion, migration and cisplatin resistance of the malignancy. Gene set enrichment, Pearson's correlation analysis and experimental results demonstrated that the VEGFA signalling pathway may be involved in the LINC02321‑regulated progression of bladder cancer. In conclusion, the six angiogenesis‑associated lncRNA signatures reported in the present study may be used to predict the prognosis of patients with bladder cancer, and LINC02321 promoted malignant progression of bladder cancer via the VEGFA signalling pathway.

Expression of GLUT4 and FAP in urothelial bladder carcinoma: correlation with angiogenesis and clinicopathological characteristics

Background

Urothelial carcinoma (UC) is the most common type of bladder cancer. Glucose transporter 4 (GLUT4) is one of glucose transporter proteins’ family which facilitates glucose transport inside the cells. It was found to be overexpressed in several malignant tumors. Cancer-associated fibroblasts (CAFs) are heterogeneous stromal cells located adjacent to cancer cells and are considered one of the most important tumor stromal cells. They have been associated with enhancing tumor growth and invasion. GLUT4 expression in malignant epithelial cells and fibroblast activation protein (FAP) expression in CAFs of UC in relation to angiogenesis and clinicopathological characteristics are studied in this work.

Materials and methods

The study was carried out on 72 paraffin blocks of UC (27 radical cystectomies and 45 transurethral resections). Immunohistochemical staining was performed with GLUT4, FAP, and CD34 antibodies. Expression of GLUT4 and FAP was classified according to the staining intensities and percentages into low and high groups. CD34-stained microvessels’ mean count in five microscopic fields (×200) was taken as the microvessel density (MVD).

Results

GLUT4 overexpression was detected in 32 UC. It was significantly associated with high-grade tumors, advanced primary tumor (pT) stage, lymphovascular invasion (LVI), and regional lymph node invasion. High FAP expression was appreciated in 27 UC and was significantly linked to LVI and advanced TNM staging. Intratumor MVD significantly increased in UC with muscle invasion, LVI, and regional lymph node and/or distant metastasis. A significant positive correlation between GLUT4, FAP expression, and MVD was found.

Conclusion

GLUT4 and FAP expression was significantly associated with increased intratumor MVD and adverse clinicopathological factors.

Single-Fiber Diffuse Reflectance Spectroscopy and Spatial Frequency Domain Imaging in Surgery Guidance: A Study on Optical Phantoms

Diffuse reflectance spectroscopy (DRS) and imaging are increasingly being used in surgical guidance for tumor margin detection during endoscopic operations. However, the accuracy of the boundary detection with optical techniques may depend on the acquisition parameters, and its evaluation is in high demand. In this work, using optical phantoms with homogeneous and heterogeneous distribution of chromophores mimicking normal and pathological bladder tissues, the accuracy of tumor margin detection using single-fiber diffuse reflectance spectroscopy and spatial frequency domain imaging was evaluated. We also showed how the diffuse reflectance response obtained at different spatial frequencies with the spatial frequency domain imaging technique could be used not only to quantitatively map absorption and scattering coefficients of normal tissues and tumor-like heterogeneities but also to estimate the tumor depth localization. The demonstrated results could be helpful for proper analysis of the DRS data measured in vivo and for translation of optical techniques for tumor margin detection to clinics.

Characteristics and clinical significance of CD163+/CD206+M2 mono-macrophage in the bladder cancer microenvironment

The tumor microenvironment may recruit monocytes, with a protumoral macrophage phenotype (M2) that plays an important role in solid tumor progression and metastasis. Therefore, it is necessary to understand the characteristics of these cells for cancer prevention and treatment. Bladder cancer tissue samples and paracarcinoma tissues samples were collected, and the expression of CD163⁺ cells in tumor tissues was observed. Then, we observed the expression of infiltrating CD45⁺CD14⁺CD163⁺ cell subset and analyzed the molecular expressions related to immunity and angiogenesis. C57/BL6 mice were inoculated subcutaneously, and dynamic changes of CD11b⁺F4/80⁺CD206⁺ mononuclear macrophages expression for tumor-bearing mice were detected. The results showed that the proportion of CD45⁺CD14⁺CD163⁺ mono-macrophage subset infiltrated by tumor tissue was significantly higher than that in paracarcinoma tissues. In bladder cancer tissue, the expression rate of CD40 in CD45⁺CD14⁺CD163^- mono-macrophage subset was significantly lower than that in CD45⁺CD14⁺CD163⁺ mono-macrophage subset. Similar results were found in the paracarcinoma tissues. We found that, as the proportion of CD11b⁺F4/80⁺CD206⁺ mono-macrophages increased gradually, the difference was statistically significant. CD163⁺/CD206⁺ mono-macrophages in bladder cancer microenvironment are abnormally elevated, and these cells are closely related to tumor progression. CD40 may be an important molecule that exerts biological function in this subset.

Significance of Vascular Endothelial Growth Factor Expression in the Bladder Urothelial Carcinoma and Its Association with Tumor Grade and Invasiveness

Background & Objective:

Vascular Endothelial Growth Factor (VEGF) is one of the newer molecular markers that acts as a central mediator of tumor angiogenesis and is essential for tumor growth, progression, and metastasis. So anti-angiogenic drugs can be used as anticancer therapy. Treatments with anti-VEGF (Bevacizumab) therapy have been proved to improve relapse-free survival in many tumors. Urinary bladder tumor has become emerging cancer globally among elderly individuals. So, the identification and development of novel biomarkers for effective treatment of urinary bladder carcinoma is essential. The present study aimed to investigate the immunohistochemical expression of VEGF in urothelial carcinoma of urinary bladder and to assess its association with tumor grade and muscle invasiveness.

Methods:

This cross-sectional study was conducted in the Department of Pathology, Chittagong Medical College, Chattogram from September 2018 to August 2020. Fifty-six formalin-fixed paraffin-embedded tissue blocks of urinary bladder carcinoma were prepared for both histopathological and immunohistochemical examination. Each slide was evaluated by at least two pathologists.

Results:

Weak to strong positive expression of VEGF were observed in 52 cases (92.86%). The proportion of tumors positive for VEGF expression was higher among patients with high grade and non-muscle invasive bladder carcinoma.

Conclusion:

We found that VEGF expression has a significant association with tumor grade and an inverse association with muscle invasion. These findings may be useful for selecting the subset of patients likely to respond to anti-VEGF targeted therapy.

The Interplay between Oxidative Stress, Inflammation and Angiogenesis in Bladder Cancer Development

In 2018, 550,000 people were diagnosed with bladder cancer (BC), of which nearly 200,000 people died. Moreover, men are 4 times more likely than women to be diagnosed with BC. The risk factors include exposure to environmental and occupational chemicals, especially tobacco smoke, benzidine and genetic factors. Despite numerous studies, the molecular basis of BC development remains unclear. A growing body of evidence suggests that inflammation, oxidant-antioxidant imbalance and angiogenesis disorders may play a significant role in the development and progression of bladder cancer. The patients with bladder cancer were characterised by an increased level of reactive oxygen species (ROS), the products of lipid peroxidation, proinflammatory cytokines and proangiogenic factors as compared to controls. Furthermore, it was shown that polymorphisms localised in genes associated with these pathways may modulate the risk of BC. Interestingly, ROS overproduction may induce the production of proinflammatory cytokines, which finally activated angiogenesis. Moreover, the available literature shows that both inflammation and oxidative stress may lead to activation of angiogenesis and tumour progression in BC patients.

Carcinogenesis and Bacillus Calmette-Guérin (BCG) Intravesical Treatment of Non-Muscle-Invasive Bladder Cancer under Tryptophan and Thymine Supplementation

PURPOSE

Evaluate tryptophan and thymine (TT) impact on carcinogenesis and intravesical BCG bladder cancer treatment.

METHODS

After identification of TT in vitro inhibitory effect in multiple cancer cell cultures, bladder cancer animal model was induced by MNU intravesical instillations and randomized into four groups: Control (n = 9), BCG (n = 9), TT (n = 7), and BCG + TT (n = 8). BCG groups received intravesical 106 CFU BCG in 0.2 ml saline for 6 consecutive weeks and TT groups received 1 g/kg (1:1) of TT via daily gavage. After 15 wk of protocol, animals were euthanized and the urinary bladders submitted to histopathology, immunohistochemistry, and Western blotting.

RESULTS

Urothelial cancer was identified in 100%, 85.7%, 44.5%, and 37.5% of Control, TT, BCG, and BCG + TT groups, respectively. Cell proliferation marked by nuclear Ki-67 was higher in the Control compared to animals in the other groups (P = 0.03). BCG, TT, and BCG + TT groups showed proliferative cell decline and TLR4/5 labeling increase in the urothelium. BCG decreased the urothelial VEGF labeling, even in TT association.

CONCLUSION

TT inhibit urothelial carcinogenesis and potentiate the intravesical BCG in the treatment of bladder cancer by reducing cell proliferation and activating TLRs.

The Dependence between Urinary Levels of Angiogenesis Factors, 8-Iso-prostaglandin F2α, ɣ-Synuclein, and Interleukin-13 in Patients with Bladder Cancer: A Pilot Study

During the last decade, a significant increase in the incidence of bladder cancer (BC) has been observed. Angiogenesis plays a key role in the process of tumor growth and metastasis. Additionally, the participation of oxidative stress and chronic inflammation in BC pathogenesis is indicated. The aim of the study was to evaluate the urinary levels of parameters of angiogenesis, stimulating angiogenin (ANG) and inhibiting angiostatin (ANGST), 8-iso-prostaglandin F2α (8-iso-PGF2α) as a marker of oxidative stress, ɣ-synuclein (SNCG) as a cancer progression parameter, and interleukin-13 (IL-13) as an anti-inflammatory immunomodulator. The levels of ANG, ANGST, 8-iso-PGF2α, SNCG, and IL-13 in the urine of BC patients and healthy controls were measured by the enzyme-linked immunosorbent assay. These parameters were examined in the whole group of BC patients and in subgroups depending on the clinical stage: nonmuscle-invasive bladder cancer (NMIBC) and muscle-invasive bladder cancer (MIBC); histopathologic malignancy: low grade (LG) and high grade (HG) and in primary and recurrent BC. Significantly, higher urinary parameters were found in BC patients in comparison to controls. Levels of all parameters increased with the development of cancer, with the exception of 8-iso-prostaglandin F2α, in which the level was higher in the early stages of the disease, but these differences were not statistically significant. Some correlations have been demonstrated between parameters in BC patients. Based on the receiver operating characteristic curves, ANG and ANGST had the best diagnostic value for BC. The obtained results indicate the important role of the examined parameters of angiogenesis, oxidative stress, and inflammation in the pathogenesis and development of BC. It is reasonable to continue research in order to thoroughly assess the impact of various associated processes on the course of BC. It is also important to carry out similar tests in patients with other urological diseases.

Angiogenesis related gene expression significantly associated with the prognostic role of an urothelial bladder carcinoma

Background

Bladder urothelial carcinoma (BLCA) is still one of the most malignant diseases and has a dismal outcome. Angiogenesis has confirmed its critical role in the development of malignant neoplasms. In this study, we uncovered the prognostic implications of the angiogenesis-related gene panel in urothelial tumors.

Methods

The RNA-seq data and clinical records of 402 patients with BLCA were collected from the TCGA database. The panel, including 145 genes involved in angiogenesis, was retrieved from the Uniprot database and the published work. The patients with similar expressed profiles were clustered, and the differences in gene expression were compared. The correlation of gene expression and BLCA outcomes or clinical features were analyzed.

Results

There were two clusters of BLCA patients identified on the expressed basis of angiogenesis-related genes. A significant difference was detected in the tumor stages between the two clusters (P<0.001) and a striking advantaged prognosis shown in cluster_1 (86.83 vs. 27.06 months, P=0.001). According to statistics, 115 genes showed a discrepancy in expression between the two clusters, and 16 genes positively correlated to tumor stage progression. Separately analyzed the correlation of those stage-related genes and overall survivals (OS) revealed that high expression of 8 genes, including ECM1 (HR =1.72, P<0.001), FN1 (HR =1.564, P=0.004), FGF1 (HR =1.519, P=0.005), FAP (HR =1.449, P=0.020), JAM3 (HR =1.396, P=0.026), THBS1 (HR =1.402, P=0.028), MFGE8 (HR =1.394, P=0.028) and COL8A2 (HR =1.388, P=0.035), were showed worse prognosis of BLCA, respectively.

Conclusions

This study showed an integrated profile of angiogenesis-related genes and identified the different BLCA subgroups with favorable prognosis and poor prognosis depended on the expression pattern of angiogenesis-related genes. Furthermore, this work revealed the single gene expressions of ECM1, FN1, FGF1, FAP, JAM3, THBS1, MFGE8 and COL8A2 involved in angiogenesis associated the prognosis remarkably.

Systemic treatment for advanced urothelial cancer: an update on recent clinical trials and current treatment options

After cisplatin-based chemotherapy became the standard treatment for metastatic urothelial cancer (mUC), very little progress has been made in the treatment landscape of this condition until recently. With increased knowledge about the molecular biology of mUC and advances in the field of cancer immunobiology, there has been an explosion in the number of clinical trials for mUC, and systemic treatment of mUC is rapidly changing. Despite the availability of several novel therapeutic agents, cisplatin-based cytotoxic chemotherapy remains the standard, first-line treatment option. Immune checkpoint inhibitors (ICIs), including programmed death-1 and programmed death ligand-1 inhibitors, are preferred second-line treatment options that are also used in first-line cisplatin-ineligible settings. For patients with actionable fibroblast growth factor receptor 2 (FGFR2) or FGFR3 genomic alterations, erdafitinib can be considered after platinum-based treatment. Enfortumab vedotin, a monoclonal antibody targeting nectin-4 conjugated to monomethyl auristatin E, has been approved for patients who do not respond to both cytotoxic chemotherapy and ICIs. In this review, we address the clinical trial data that have established the current standard treatments and ongoing clinical trials of various agents with different mechanisms as well as provide a brief overview of current practice guidelines and recommendations in patients with mUC.

Preliminary Study on Selected Markers of Oxidative Stress, Inflammation and Angiogenesis in Patients with Bladder Cancer

In recent years, bladder cancer (BC) has been reported as one of the most commonly occurring cancers among older people, and its detection is still difficult. Therefore, there is a need to search for additional useful markers of disease. Some studies indicate the important roles of inflammation and oxidative stress (OS) in bladder tumour pathogenesis. The aim of this study was to examine the levels of selected markers of OS, inflammation and angiogenesis in blood plasma/serum samples derived from patients with BC, and a healthy control group. Moreover the degrees of change and strength of correlation between values of the analysed markers and tumour stage or grade were estimated. Concentrations of: malondialdehyde (MDA) and advanced oxidation protein products (AOPP), and total antioxidant status (TAS) divided into slow (TAS-s) and fast (TAS-f) antioxidants (spectrophotometric measurement), angiogenin (ANG) (immunoenzymatic method) and C-reactive protein (CRP) (immunoturbidimetric method) were determined in both the studied groups. The majority of values of the examined parameters were significantly higher among patients, while subfractions of TAS were significantly lower in comparison to the control group. Moreover, different values and different strengths of correlation between the examined parameters and cancer stage or grade were noticed. The most significant changes for CRP were observed in T2 and for MDA in G3, while the lowest TAS-f activity was revealed in G1 patients. Increased values of OS parameters, angiogenesis and inflammation markers, in combination with reduced TAS subfractions activity in BC are important in its pathogenesis and will be helpful in estimation of patients' condition.

Prostate Cancer Vascularity: Superb Microvascular Imaging Ultrasonography with Histopathology Correlation

Background

The aim of this study was to evaluate the association between prostate cancer (PCa) vascularity detected by superb microvascular imaging (SMI) and Gleason score in biopsy specimens.

Material/Methods

A total of 119 patients with suspected PCa before biopsy underwent gray-scale ultrasound (US), color Doppler ultrasound (CDUS), and SMI imaging between June 2018 and March 2019. Vascularity quantity was assessed by SMI and compared with that of CDUS. The vessel parameter was also compared with the Gleason score. The sensitivity of PCa was compared between transrectal ultrasound guided systematic biopsy (SB) and SMI-guided targeted biopsy (SMI-guided TB).

Results

Pathology confirmed 74 of 119 patients had PCa. The microvascular quantity of PCa patients was significantly higher than that of non-malignant patients. SMI detected blood vessels in 97.3% (72/74) in the malignant group, while CDUS identified blood flow signals in 90.5% (67/74) of the PCa group. SMI visualized enriched microvascular in PCa of Gleason 8 (54.5%) and Gleason 9 (92.3%). There was a positive correlation between microvascular quantity detected by SMI and Gleason score, with a correlation coefficient of 0.373 (P<0.001). SMI-guided TB cores were significantly more likely than SB cores to detect PCa (OR=12.83, P<0.001).

Conclusions

SMI could be promising as a useful imaging technique in the detection and characterization of PCa. There was a positive correlation between microvascular quantity detected by SMI and Gleason score.

Protein Glycosylation and Tumor Microenvironment Alterations Driving Cancer Hallmarks

Decades of research have disclosed a plethora of alterations in protein glycosylation that decisively impact in all stages of disease and ultimately contribute to more aggressive cell phenotypes. The biosynthesis of cancer-associated glycans and its reflection in the glycoproteome is driven by microenvironmental cues and these events act synergistically toward disease evolution. Such intricate crosstalk provides the molecular foundations for the activation of relevant oncogenic pathways and leads to functional alterations driving invasion and disease dissemination. However, it also provides an important source of relevant glyco(neo)epitopes holding tremendous potential for clinical intervention. Therefore, we highlight the transversal nature of glycans throughout the currently accepted cancer hallmarks, with emphasis on the crosstalk between glycans and the tumor microenvironment stromal components. Focus is also set on the pressing need to include glycans and glycoconjugates in comprehensive panomics models envisaging molecular-based precision medicine capable of improving patient care. We foresee that this may provide the necessary rationale for more comprehensive studies and molecular-based intervention.

Bladder cancer cells interact with vascular endothelial cells triggering EGFR signals to promote tumor progression

Although important progress has been made in elucidating the role of the tumor microenvironment in the development of bladder cancer, little is currently known regarding the interactions with vascular endothelial cells (ECs) that promote cancer progression. In the present study, it is reported that epidermal growth factor receptor ligands induced by the upregulation of vascular endothelial growth factor (VEGF)-A and VEGF-C via the VEGF receptor (R)2/nuclear factor-κB signaling pathway in ECs, may trigger EGFR signaling in bladder cancer cells and promote bladder cancer progression. Furthermore, the interaction between bladder cancer cells and ECs enhanced EC recruitment though the CXCL1/CXCL5/CXCL8-CXCR2 pathway. Western blotting was used to evaluate the presence of VEGFR, EGFR and nuclear factor-κB, and reverse transcription-quantitative polymerase chain reaction was used to evaluate the expression of VEGFR ligands and EGFR ligands. The present results indicate the mechanism by which the indirect interplay between bladder cancer cells and vascular ECs promotes cancer progression, through the VEGFR2 signaling pathway in vascular ECs and through the EGFR signaling pathway in bladder cancer cells.

Everolimus and pazopanib (E/P) benefit genomically selected patients with metastatic urothelial carcinoma

BACKGROUND

Metastatic urothelial carcinoma (mUC) is a genomically diverse disease with known alterations in the mTOR pathway and tyrosine kinases including FGFR. We investigated the efficacy and safety of combination treatment with everolimus and pazopanib (E/P) in genomically profiled patients with mUC.

METHODS

mUC patients enrolled on a Phase I dose escalation study and an expansion cohort treated with E/P were included. The primary end point was objective response rate (ORR); secondary end points were safety, duration of response (DOR), progression-free survival (PFS) and overall survival (OS). Patients were assessed for mutations and copy number alterations in 300 relevant cancer-associated genes using next-generation sequencing and findings were correlated with outcomes. Time-to-event data were estimated with Kaplan-Meier methods.

RESULTS

Of the 23 patients enrolled overall, 19 had mUC. ORR was 21% (one complete response (CR), three partial responses (PR), eight with stable disease (SD). DOR, PFS and OS were 6.5, 3.6, and 9.1 months, respectively. Four patients with clinical benefit (one CR, two PR, one SD) had mutations in TSC1/TSC2 or mTOR and a 5th patient with PR had a FGFR3-TACC3 fusion.

CONCLUSIONS

Combination therapy with E/P is safe in mUC and select patients with alterations in mTOR or FGFR pathways derive significant clinical benefit.

Lysyl oxidase inhibition via β-aminoproprionitrile hampers human umbilical vein endothelial cell angiogenesis and migration in vitro

Lysyl oxidase (LOX) is an enzyme that oxidizes lysine residues in collagens and elastin. It stabilizes or remodels the extracellular matrix and basement membrane of blood vessels. Current oncology studies have revealed that LOX is upregulated in invasive cancer cells and bolstered cell movement, and LOX was observed to promote the angiogenesis and migration of endothelial cells. In the present study, angiogenesis and migration were examined in human umbilical vein endothelial cells (HUVECs). Following cell treatment with 0.1-0.4 mM β-aminoproprionitrile (BAPN), a specific inhibitor of LOX, angiogenesis was analyzed with a fibrin gel in vitro angiogenesis assay kit and migration was examined via a Boyden Chamber assay. Angiogenesis-associated gene expression was investigated with a microarray assay and confirmed with reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The results showed that HUVEC angiogenesis substantially increased in the presence of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF) and phorbol 12-myristate 13-acetate (PMA). In addition, LOX inhibition blocked the angiogenesis stimulated by VEGF bFGF and PMA, and the inhibition of LOX reduced the migration of HUVECs. Furthermore, the microarray and RT-qPCR revealed that BAPN downregulated myeloid progenitor inhibitory factor 1, and western blot analysis demonstrated that BAPN decreased the phosphorylation of MAPK and Akt, suggesting that the specific inhibitor of LOX, BAPN, may serve as an alternative strategy for preventing angiogenesis.

Inhibition of angiogenesis by leflunomide via targeting the soluble ephrin-A1/EphA2 system in bladder cancer

Angiogenesis plays an important role in bladder cancer (BCa). The immunosuppressive drug leflunomide has attracted worldwide attention. However, the effects of leflunomide on angiogenesis in cancer remain unclear. Here, we report the increased expression of soluble ephrin-A1 (sEphrin-A1) in supernatants of BCa cell lines (RT4, T24, and TCCSUP) co-cultured with human umbilical vein endothelial cells (HUVECs) compared with that in immortalized uroepithelial cells (SV-HUC-1) co-cultured with HUVECs. sEphrin-A1 is released from BCa cells as a monomeric protein that is a functional form of the ligand. The co-culture supernatants containing sEphrin-A1 caused the internalization and down-regulation of EphA2 on endothelial cells and dramatic functional activation of HUVECs. This sEphrin-A1/EphA2 system is mainly functional in regulating angiogenesis in BCa tissue. We showed that leflunomide (LEF) inhibited angiogenesis in a N-butyl-N-(4-hydroxybutyl)-nitrosamine (BBN)-induced bladder carcinogenesis model and a tumor xenograft model, as well as in BCa cell and HUVEC co-culture systems, via significant inhibition of the sEphrin-A1/EphA2 system. Ephrin-A1 overexpression could partially reverse LEF-induced suppression of angiogenesis and subsequent tumor growth inhibition. Thus, LEF has a significant anti-angiogenesis effect on BCa cells and BCa tissue via its inhibition of the functional angiogenic sEphrin-A1/EphA2 system and may have potential for treating BCa beyond immunosuppressive therapy.