Anti-angiogenesis for cancer: Current status and prospects

An update to experimental and clinical aspects of tumor-associated macrophages in cancer development: hopes and pitfalls

Tumor-associated macrophages (TAMs) represent one of the most abundant tumor-infiltrating stromal cells, and their normal function in tumor microenvironment (TME) is to suppress tumor cells by producing cytokines which trigger both direct cell cytotoxicity and antibody-mediated immune response. However, upon prolonged exposure to TME, the classical function of these so-called M1-type TAMs can be converted to another type, "M2-type," which are recruited by tumor cells so that they promote tumor growth and metastasis. This is the reason why the accumulation of TAMs in TME is correlated with poor prognosis in cancer patients. Both M1- and M2-types have high degree of plasticity, and M2-type cells can be reprogrammed to M1-type for therapeutic purposes. This characteristic introduces TAMs as promising target for developing novel cancer treatments. In addition, inhibition of M2-type cells and blocking their recruitment in TME, as well as their depletion by inducing apoptosis, are other approaches for effective immunotherapy of cancer. In this review, we summarize the potential of TAMs to be targeted for cancer immunotherapy and provide an up-to-date about novel strategies for targeting TAMs.

Clinical significance and immune landscape of angiogenesis-related genes in bladder cancer

BACKGROUND

Angiogenesis is a major promotor of tumor progression and metastasis. Nevertheless, it is undetermined how angiogenesis-related genes (ARGs) influence bladder cancer.

METHODS

The profiles of bladder cancer gene expression were collected from the TCGA-BLCA cohort. The LASSO regression analysis was used to build an angiogenesis-related signature (ARG_score) with the prognostic ARGs. Verification analyses were conducted across the GSE48075 dataset to demonstrate the robustness of the signature. Differences between the two risk groups based on clinical outcomes, immune landscape, mutation status, chemotherapeutic effectiveness for anticancer drugs, and immunotherapy efficacy were analyzed. A nomogram was developed to improve the clinical efficacy of this predictive tool. The expression levels of model genes in normal bladder epithelial cell lines (SV-HUC-1) and bladder cancer cell lines (T24 and 5637) were detected by qRT-PCR assay.

RESULTS

Four angiogenesis-associated gene signature was constructed based on the LASSO regression algorithm. The signature showed independent risk factors of overall survival for bladder cancer, validated using two external survival datasets. Additionally, we built a prognostic nomogram to improve the practicality of the ARG_score. High-risk individuals showed stronger immunocyte infiltration, immune-related functions, elevated expression of immune checkpoints, reduced TIDE score, and higher combined IPS-PD-1 and IPS-CTLA4 scores, suggesting a heightened responsiveness to immune checkpoint inhibitors. Furthermore, patients with low and high risk showed distinct responsiveness to anticancer drugs. The expression levels of 5 model genes (COL5A2, JAG1, MSX1, OLR1, and STC) were significantly increased in bladder cancer cell lines (T24 and 5637) compared with the normal bladder epithelial cell line SV-HUC-1.

CONCLUSIONS

The model constructed based on ARGs may have wide application in predicting outcomes and therapeutic responses.

A human VEGF magnetic molecularly imprinted polymer for drug-free anti-angiogenesis and photothermal therapy of tumors

A magnetic molecularly imprinted polymer was developed with an epitope peptide of human VEGF as a template via an epitope blotting technique. As a drug-free agent, the nanoparticles can significantly suppress the proliferation of tumor cells by integrating anti-angiogenesis and photothermotherapy. This work provides a successful example of the design of multimodal antineoplastic drugs.

The role of angiogenesis in melanoma: Clinical treatments and future expectations

The incidence of melanoma has increased rapidly over the past few decades, with mortality accounting for more than 75% of all skin cancers. The high metastatic potential of Melanoma is an essential factor in its high mortality. Vascular angiogenic system has been proved to be crucial for the metastasis of melanoma. An in-depth understanding of angiogenesis will be of great benefit to melanoma treatment and may promote the development of melanoma therapies. This review summarizes the recent advances and challenges of anti-angiogenic agents, including monoclonal antibodies, tyrosine kinase inhibitors, human recombinant Endostatin, and traditional Chinese herbal medicine. We hope to provide a better understanding of the mechanisms, clinical research progress, and future research directions of melanoma.

Research progress on the antitumor effects of astragaloside IV

One of the most important and effective components of Astragalus membranaceus is astragaloside IV (AS-IV), which can exert anti-tumor effects through various pathways. For instance, AS-IV exerts an anti-tumor effect by acting at the cellular level, regulating the phenotype switch of tumor-associated macrophages, or inhibiting the development of tumor cells. Furthermore, AS-IV inhibits tumor cell progression by enhancing its sensitivity to antitumor drugs or reversing the drug resistance of tumor cells. This article reviews the different mechanisms of AS-IV inhibition of epithelial-mesenchymal transition (EMT), migration, proliferation, and invasion of tumor cells, inducing apoptosis and improving the sensitivity of anti-tumor drugs. This review summarizes recent progress in the current research into AS-IV anti-tumor effect and provides insight on the next anti-tumor research of AS-IV.

Targeting cancer stem cells in the tumor microenvironment: An emerging role of PARP inhibitors

Cancer stem cells (CSCs) constitute a small population of cancer cells in the tumor microenvironment (TME), which are responsible for metastasis, angiogenesis, drug resistance, and cancer relapse. Understanding the key signatures and resistance mechanisms of CSCs may help in the development of novel chemotherapeutic strategies to specifically target CSCs in the TME. PARP inhibitors (PARPi) are known to enhance the chemosensitivity of cancer cells to other chemotherapeutic agents by inhibiting the DNA repair pathways and chromatin modulation. But their effects on CSCs are still unknown. Few studies have reported that PARPi can stall replication fork progression in CSCs. PARPi also have the potential to overcome chemoresistance in CSCs and anti-angiogenic potentiality as well. Previous reports have suggested that epigenetic drugs can synergistically ameliorate the anti-cancer activities of PARPi through epigenetic modulations. In this review, we have systematically discussed the effects of PARPi on different DNA repair pathways with respect to CSCs and also how CSCs can be targeted either as monotherapy or as a part of combination therapy. We have also talked about how PARPi can help in reversal of chemoresistance of CSCs and the role of PARPi in epigenetic modifications to hinder cancer progression. We have also elaborated on the aspects of research that need to be investigated for development of successful therapeutic interventions using PARPi to specifically target CSCs in the TME.

Targeting the Tumor Microenvironment: A Close Up of Tumor-Associated Macrophages and Neutrophils

The importance of the tumor microenvironment (TME) in dynamically regulating cancer progression and influencing the therapeutic outcome is widely accepted and appreciated. Several therapeutic strategies to modify or modulate the TME, like angiogenesis or immune checkpoint inhibitors, showed clinical efficacy and received approval from regulatory authorities. Within recent decades, new promising strategies targeting myeloid cells have been implemented in preclinical cancer models. The predominance of specific cell phenotypes in the TME has been attributed to pro- or anti-tumoral. Hence, their modulation can, in turn, alter the responses to standard-of-care treatments, making them more or less effective. Here, we summarize and discuss the current knowledge and the correlated challenges about the tumor-associated macrophages and neutrophils targeting strategies, current treatments, and future developments.

Rh-Endostatin Plus Irinotecan/Cisplatin as Second-Line Therapy for Advanced Esophageal Squamous Cell Carcinoma: An Open-Label, Phase II Study

Background

This open-label, phase II study aimed to investigate the efficacy and safety of recombinant human endostatin (Rh-endostatin) plus irinotecan/cisplatin as second-line treatment in patients with advanced esophageal squamous cell carcinoma (ESCC).

Methods

Eligible patients received 15mg/m² Rh-endostatin as a continuous intravenous pump infusion (7 continuous days), 60mg/m² irinotecan (days 1 and 8), and 60mg/m² cisplatin (day 1) every 3 weeks. The primary endpoint was progression-free survival (PFS).

Results

A total of 50 patients were assessable for efficacy and safety analysis. The median follow-up was 10.97 months (95%CI: 7.03-19.42) as the data cutoff. Median PFS was 4.01 months (95% CI: 3.19-5.49), and median overall survival (OS) was 12.32 months (95% CI: 8.21-17.45); 13 (26%; 95% CI: 15.87-39.55) of 50 patients had an objective response, and 31 (62%; 95% CI: 48.15-74.14) had disease control. Grade 3 or greater treatment-related adverse events (AEs) occurred in 12 (24.0%) patients, and no deaths were reported. The common grade 3 or greater AEs were leucopenia (18.0%) and neutropenia (16.0%). Five (10%) patients discontinued treatment because of AEs.

Conclusion

Rh-endostatin plus irinotecan/cisplatin showed promising anti-tumor activity in advanced ESCC patients with a good safety profile in the second-line setting, which warrants further study in this population. (ClinicalTrials.gov identifier: NCT03797625).

Cholenic acid derivative UniPR1331 impairs tumor angiogenesis via blockade of VEGF/VEGFR2 in addition to Eph/ephrin

Angiogenesis, the formation of new blood vessels from preexisting ones, is crucial for tumor growth and metastatization, and is considered a promising therapeutic target. Unfortunately, drugs directed against a specific proangiogenic growth factor or receptor turned out to be of limited benefit for oncology patients, likely due to the high biochemical redundancy of the neovascularization process. In this scenario, multitarget compounds that are able to simultaneously tackle different proangiogenic pathways are eagerly awaited. UniPR1331 is a 3β-hydroxy-Δ⁵-cholenic acid derivative, which is already known to inhibit Eph-ephrin interaction. Here, we employed an analysis pipeline consisting of molecular modeling and simulation, surface plasmon resonance spectrometry, biochemical assays, and endothelial cell models to demonstrate that UniPR1331 directly interacts with the vascular endothelial growth factor receptor 2 (VEGFR2) too. The binding of UniPR1331 to VEGFR2 prevents its interaction with the natural ligand vascular endothelial growth factor and subsequent autophosphorylation, signal transduction, and in vitro proangiogenic activation of endothelial cells. In vivo, UniPR1331 inhibits tumor cell-driven angiogenesis in zebrafish. Taken together, these data shed light on the pleiotropic pharmacological effect of UniPR1331, and point to Δ⁵-cholenic acid as a promising molecular scaffold for the development of multitarget antiangiogenic compounds.

Cardiac glycosides from Digitalis lanata and their cytotoxic activities

Cardiac glycosides (CGs) are good candidates as drug leads in the treatment of cancer because of their structural diversities and potent biological activities. In this study, fifteen CGs including three new ones (1–3) were isolated from Digitalis lanata Ehrh. Their structures were elucidated by HRESIMS, NMR spectroscopic methods, including homonuclear and heteronuclear coupling constant analysis, and acid-catalyzed hydrolysis and derivatization analysis of the sugar chain. The cytotoxic activities of these CGs were evaluated against three human cancer cell lines (A549, HeLa and MCF-7 cell lines), and all of them showed strong activities at nanomolar scale. The flow cytometric analysis indicated that compound 1 induced cell cycle arrest in the G2/M phase. Transcriptome analysis revealed a panel of possible targets for compound 1. RT-PCR and western blot experiments showed that 1 significantly inhibited the expression of vasohibin-2 (VASH2). Moreover, compound 1 restrained angiogenesis in a concentration-dependent manner in the chick embryo chorioallantoic membrane (CAM) model.

Cardiac glycosides (CGs) are good candidates as drug leads in the treatment of cancer because of their structural diversities and potent biological activities.

The Chemokine-Based Peptide, CXCL9(74-103), Inhibits Angiogenesis by Blocking Heparan Sulfate Proteoglycan-Mediated Signaling of Multiple Endothelial Growth Factors

Simple Summary

Major angiogenic growth factors activate downstream signaling cascades by interacting with both receptor tyrosine kinases (RTKs) and cell surface proteoglycans, such as heparan sulfate proteoglycans (HSPGs). As current anti-angiogenesis regimens in cancer are often faced with resistance, alternative therapeutic strategies are highly needed. The aim of our study was to investigate the impact on angiogenic signaling when we interfered with growth factor-HSPG interactions using a CXCL9 chemokine-derived peptide with high affinity for HS.

Abstract

Growth factors such as vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF) and epidermal growth factor (EGF) are important angiogenesis-mediating factors. They exert their effects not only through their respective receptor tyrosine kinases (RTKs), but they also require molecular pairing with heparan sulfate proteoglycans (HSPGs). Angiogenic growth factors and their signaling pathways are commonly targeted in current anti-angiogenic cancer therapies but have unfortunately insufficient impact on patient survival. Considering their obvious role in pathological angiogenesis, HS-targeting drugs have become an appealing new strategy. Therefore, we aimed to reduce angiogenesis through interference with growth factor-HS binding and downstream signaling using a CXCL9-derived peptide with a high affinity for glycosaminoglycans (GAGs), CXCL9(74-103). We showed that CXCL9(74-103) reduced EGF-, VEGF165- and FGF-2-mediated angiogenic processes in vitro, such as endothelial cell proliferation, chemotaxis, adhesion and sprouting, without exerting cell toxicity. CXCL9(74-103) interfered with growth factor signaling in diverse ways, e.g., by diminishing VEGF165 binding to HS and by direct association with FGF-2. The dependency of CXCL9(74-103) on HS for binding to HMVECs and for exerting its anti-angiogenic activity was also demonstrated. In vivo, CXCL9(74-103) attenuated neovascularization in the Matrigel plug assay, the corneal cauterization assay and in MDA-MB-231 breast cancer xenografts. Additionally, CXCL9(74-103) reduced vascular leakage in the retina of diabetic rats. In contrast, CXCL9(86-103), a peptide with low GAG affinity, showed no overall anti-angiogenic activity. Altogether, our results indicate that CXCL9(74-103) reduces angiogenesis by interfering with multiple HS-dependent growth factor signaling pathways.

Inhibition of Hepatic Stellate Cell Activation Suppresses Tumorigenicity of Hepatocellular Carcinoma in Mice

Transdifferentiation (or activation) of hepatic stellate cells (HSCs) to myofibroblasts is a key event in liver fibrosis. Activated HSCs in the tumor microenvironment reportedly promote tumor progression. This study analyzed the effect of an inhibitor of HSC activation, retinol-binding protein–albumin domain III fusion protein (R-III), on protumorigenic functions of HSCs. Although conditioned medium collected from activated HSCs enhanced the migration, invasion, and proliferation of the hepatocellular carcinoma cell line Hepa-1c1c7, this effect was not observed in Hepa-1c1c7 cells treated with conditioned medium from R-III–exposed HSCs. In a subcutaneous tumor model, larger tumors with increased vascular density were formed in mice transplanted with Hepa-1c1c7+HSC than in mice transplanted with Hepa-1c1c7 cells alone. Intriguingly, when Hepa-1c1c7+HSC–transplanted mice were injected intravenously with R-III, a reduction in vascular density and extended tumor necrosis were observed. In an orthotopic tumor model, co-transplantation of HSCs enhanced tumor growth, angiogenesis, and regional metastasis accompanied by increased peritumoral lymphatic vessel density, which was abolished by R-III. In vitro study showed that R-III treatment affected the synthesis of pro-angiogenic and anti-angiogenic factors in activated HSCs, which might be the potential mechanism underlying the R-III effect. These findings suggest that the inhibition of HSC activation abrogates HSC-induced tumor angiogenesis and growth, which represents an attractive therapeutic strategy.

Anti-angiogenesis Function of Ononin via Suppressing the MEK/Erk Signaling Pathway

Angiogenesis is a complicated pathological process and plays an important role in modulating tumor development. Flavonoids, sharing the basic functional group with estrogen, have been utilized as chemopreventive agents to inhibit endothelial cell angiogenesis and also suppress tumor cell proliferation. Ononin, also referred to as formononetin-7-O-β-d-glucoside, is one of the bioactive chemicals found within many functional food or plants. The anticancer functions of ononin have been reported both in vitro and in vivo. However, the anti-angiogenetic properties of ononin have not been reported. The possible efficacies of ononin against angiogenesis was verified in cultured endothelial cells. Ononin suppressed vascular endothelial growth factor (VEGF)-induced HUVEC migration, invasion. and tube formation activity after 48 h. The apoptosis rate and specific markers, i.e., Bax/Bc-2 ratio, cleaved caspase 3/9 (Cl-caspase 3/9), and cytochrome c (Cyto c), were enhanced in the ononin-treated group. On the other hand, the protein expressions levels of hypoxia-inducible factor 1α (HIF-1α), mitogen-activated protein kinase kinase (MEK)/extracellular signal-regulated kinase (ERK), and vascular endothelial growth factor receptor 2 (VEGFR2) were restricted after ononin treatment for 2 days in VEGF-pretreated endothelial cells. In summary, ononin acts as a candidate for angiogenetic-related disease prevention and treatment.

Small molecules in targeted cancer therapy: advances, challenges, and future perspectives

Due to the advantages in efficacy and safety compared with traditional chemotherapy drugs, targeted therapeutic drugs have become mainstream cancer treatments. Since the first tyrosine kinase inhibitor imatinib was approved to enter the market by the US Food and Drug Administration (FDA) in 2001, an increasing number of small-molecule targeted drugs have been developed for the treatment of malignancies. By December 2020, 89 small-molecule targeted antitumor drugs have been approved by the US FDA and the National Medical Products Administration (NMPA) of China. Despite great progress, small-molecule targeted anti-cancer drugs still face many challenges, such as a low response rate and drug resistance. To better promote the development of targeted anti-cancer drugs, we conducted a comprehensive review of small-molecule targeted anti-cancer drugs according to the target classification. We present all the approved drugs as well as important drug candidates in clinical trials for each target, discuss the current challenges, and provide insights and perspectives for the research and development of anti-cancer drugs.

The roles of tumor-associated macrophages in tumor angiogenesis and metastasis

Tumor associated macrophages (TAMs) are the most frequent immune cells within tumor microenvironment (TME). There is growing evidence that TAMs are involved in tumor progression via multiple mechanisms. TAMs create an immunosuppressive TME by producing growth factors, chemokines, and cytokines which modulate recruitment of immune cells and inhibit anti-tumor responses. They also serve as angiogenesis promoting cells by production of pro-angiogenic factors and matrix metalloproteinases (MMPs) and vascular constructing which guarantee supplying oxygen and nutrients to solid tumor cells. Furthermore, TAMs play important functions in tumor metastasis through contributing to invasion, extravasation, survival, intravasation, and colonization of tumor cells. In this review, we summarized macrophage classification, TAMs polarization, and mechanisms underlying TAM-promoting angiogenesis and metastasis.

Roles of lncRNAs in cancer: Focusing on angiogenesis

Approximately 98% of the human genome consists of non-coding sequences that are classified into two classes by size: small non-coding RNAs (≤200 nucleotides) and long non-coding RNAs (≥200 nucleotides). Long non-coding RNAs (lncRNAs) are involved in various cellular events and act as guides, signals, decoys, and dynamic scaffolds. Due to their oncogenic and tumor suppressive roles, lncRNAs are important in cancer development and growth. LncRNAs play their roles by modulating cancer hallmarks, including DNA damage, metastasis, immune escape, cell stemness, drug resistance, metabolic reprogramming, and angiogenesis. Angiogenesis is vital for solid tumors which guarantees their growth beyond 2 mm³. Tumor angiogenesis is a complex process and is regulated through interaction between pro-angiogenic and anti-angiogenic factors within the tumor microenvironment. There are accumulating evidence that different lncRNAs regulate tumor angiogenesis. In this paper, we described the functions and mechanisms of lncRNAs in tumor angiogenesis.

Gastrointestinal Injury Related to Antiangiogenesis Cancer Therapy

BACKGROUND

Data on gastrointestinal toxicities related antiangiogenesis cancer therapy is very limited. We aim to describe the clinical, endoscopic, and histologic features and outcomes of antiangiogenesis-associated colitis and diarrhea (ACD) at a tertiary-care cancer center.

PATIENTS AND METHODS

We performed a retrospective study of cancer patients who received antiangiogenesis therapy (AAT) and underwent endoscopy for ACD symptoms during 2000-2018.

RESULTS

A total of 12,045 patients received AAT during the study period. Of these, 552 patients underwent lower gastrointestinal tract endoscopic evaluation after AAT. Among them, we identified 41 patients who developed ACD. The median time from AAT initiation to ACD onset was 20 weeks. Most patients received bevacizumab (83%). The median duration of ACD symptoms was 6 days. On endoscopy, 7 patients (17%) had mucosal ulceration, and 16 (39%) had nonulcerative inflammation. Active histologic inflammation was evident in 8 patients (20%). Thirteen patients (32%) received treatment for ACD: antibiotics in 5 (12%) and antimotility agents in 11 (27%). Sixteen patients (39%) were hospitalized for ACD, and 2 were admitted to the intensive care unit. One colonic perforation (2%) related to underlying malignancy was reported after colonoscopy. Patients with enterocolitis symptoms had more frequent abnormal endoscopic findings (P = .024) and less frequently received antimotility agents (P = .011) compared to those with diarrhea only. Abnormal endoscopic findings were associated with more hospitalizations (P = .063) compared to normal group.

CONCLUSION

ACD is a rare adverse event of AAT and is usually mild. Despite its rarity, complications of ACD can be serious, requiring intensive care unit and surgery. Colonic perforation occurred after routine endoscopy after AAT in 2% of our cohort.

Astragaloside IV inhibits lung cancer progression and metastasis by modulating macrophage polarization through AMPK signaling

BACKGROUND

Accumulating evidence suggests that M2-polarized tumor-associated macrophages (TAMs) play an important role in cancer progression and metastasis, making M2 polarization of TAMs an ever more appealing target for therapeutic intervention. Astragaloside IV (AS-IV), a saponin component isolated from Astragali radix, has been reported to inhibit the invasion and metastasis of lung cancer, but its effects on TAMs during lung cancer progression have not been investigated.

METHODS

Human THP-1 monocytes were induced to differentiate into M2 macrophages through treatments with IL-4, IL-13, and phorbol myristate acetate (PMA). We used the lung cancer cell lines A549 and H1299 cultured in conditioned medium from M2 macrophages (M2-CM) to investigate the effects of AS-IV on tumor growth, invasion, migration, and angiogenesis of lung cancer cells. Macrophage subset distribution, M1 and M2 macrophage-associated markers, and mRNA expression were analyzed by flow cytometry and quantitative PCR. The activation of adenosine monophosphate-activated protein kinase (AMPK) signaling pathways that mediate M2-CM-promoted tumor migration was detected using western blotting.

RESULTS

Here we found that AS-IV significantly inhibited IL-13 and IL-4-induced M2 polarization of macrophages, as illustrated by reduced expression of CD206 and M2-associated genes, and that AS-IV suppressed the M2-CM-induced invasion, migration, and angiogenesis of A549 and H1299 cells. In vivo experiments demonstrated that AS-IV greatly inhibited tumor growth and reduced the number of metastases of Lewis lung cancer. The percentage of M2 macrophages was decreased in tumor tissue after AS-IV treatment. Furthermore, AS-IV inhibited AMPKα activation in M2 macrophages, and silencing of AMPKα partially abrogated the inhibitory effect of AS-IV.

CONCLUSIONS

AS-IV reduced the growth, invasion, migration, and angiogenesis of lung cancer by blocking the M2 polarization of macrophages partially through the AMPK signaling pathway, which appears to play an important role in AS-IV's ability to inhibit the metastasis of lung cancer.