Stimulate Tumor Angiogenesis Research Articles

Endosialin in Cancer: Expression Patterns, Mechanistic Insights, and Therapeutic Approaches.

Endosialin, also known as tumor endothelial marker 1 (TEM1) or CD248, is a single transmembrane glycoprotein with a C-type lectin-like domain. Endosialin is mainly expressed in the stroma, especially in cancer-associated fibroblasts and pericytes, in most solid tumors. Endosialin is also expressed in tumor cells of most sarcomas. Endosialin can promote tumor progression through different mechanisms, such as promoting tumor cell proliferation, adhesion and migration, stimulating tumor angiogenesis, and inducing an immunosuppressive tumor microenvironment. Thus, it is considered an ideal target for cancer treatment. Several endosialin-targeted antibodies and therapeutic strategies have been developed and have shown preliminary antitumor effects. Here, we reviewed the endosialin expression pattern in different cancer types, discussed the mechanisms by which endosialin promotes tumor progression, and summarized current therapeutic strategies targeting endosialin.

Inhibition of transforming growth factor-β signals suppresses tumor formation by regulation of tumor microenvironment networks.

The tumor microenvironment (TME) consists of cancer cells surrounded by stromal components including tumor vessels. Transforming growth factor-β (TGF-β) promotes tumor progression by inducing epithelial-mesenchymal transition (EMT) in cancer cells and stimulating tumor angiogenesis in the tumor stroma. We previously developed an Fc chimeric TGF-β receptor containing both TGF-β type I (TβRI) and type II (TβRII) receptors (TβRI-TβRII-Fc), which trapped all TGF-β isoforms and suppressed tumor growth. However, the precise mechanisms underlying this action have not yet been elucidated. In the present study, we showed that the recombinant TβRI-TβRII-Fc protein effectively suppressed invitro EMT of oral cancer cells and invivo tumor growth in a human oral cancer cell xenograft mouse model. Tumor cell proliferation and angiogenesis were suppressed in tumors treated with TβRI-TβRII-Fc. Molecular profiling of human cancer cells and mouse stroma revealed that K-Ras signaling and angiogenesis were suppressed. Administration of TβRI-TβRII-Fc protein decreased the expression of heparin-binding epidermal growth factor-like growth factor (HB-EGF), interleukin-1β (IL-1β) and epiregulin (EREG) in the TME of oral cancer tumor xenografts. HB-EGF increased proliferation of human oral cancer cells and mouse endothelial cells by activating ERK1/2 phosphorylation. HB-EGF also promoted oral cancer cell-derived tumor formation by enhancing cancer cell proliferation and tumor angiogenesis. In addition, increased expressions of IL-1β and EREG in oral cancer cells significantly enhanced tumor formation. These results suggest that TGF-β signaling in the TME controls cancer cell proliferation and angiogenesis by activating HB-EGF/IL-1β/EREG pathways and that TβRI-TβRII-Fc protein is a promising tool for targeting the TME networks.

Potential targets of heparin during progression and metastasis of malignant neoplasms

In the modern world, oncological diseases occupy the leading positions in the structure of mortality. An integrated approach to oncotherapy is not only aimed at immediate affection of malignant tumors, but also directed at reducing the risk of tumor recurrence and metastasis, as well as alleviating side effects of chemotherapy and radiotherapy of the disease. In oncologic disorders, blood viscosity increases, thus being associated with hypercoagulation syndrome. To prevent its consequences, the direct and indirect anticoagulants, especially heparin and its derivatives, are actively used. Biological functions and structural features of heparin make it a potential universal platform of a drug development for broad application, including oncology. With the advent of heparin fractionation technology and preparation of low-molecular weight forms and their derivatives, it has become possible to focus not only on anticoagulant activity but also to obtain fractions with targeted pharmacological activity. Usage of the anticoagulants has shown their antitumor activity in some cases, thus providing a basis for a more detailed study of pharmacotherapeutic effects of this group of drugs. Currently, some data suggest various pathways of interaction between heparin and tumor cells. There are multiple common features in development of a primary tumor and formation of secondary distant metastases, which may be attributed to similar molecular cellular mechanisms. The molecules mediating intercellular interactions, both between the tumor cells and between malignant cells and tumor-associated immune cells (e.g., lymphocytes and macrophages) may serve as targets for heparin thus helping the tumor to evade immune surveillance. The cytokines that stimulate tumor angiogenesis represent another important therapeutic target. Heparin derivatives are able to suppress tumor activity and prevent metastatic processes at various stages by inhibiting heparanase, P-/L-selectin, and angiogenesis activity, modulating the CXCL12-CXCR4 chemokine axis, and regulating OAM activity.This brief review addresses the current understanding and application of the potentially antimetastatic properties of heparin and its derivatives in malignant bone tumors since the heparin-based drugs are used as anticoagulants in arthroplasty of large joints and bone defects in patients with osteosarcoma.

Abstract P2-14-01: MOLECULAR FLUORESCENCE-GUIDED SURGERY USING BEVA800 FOR THE ASSESSMENT OF TUMOR MARGINS DURING BREAST CONSERVING SURGERY OF PATIENTS WITH PRIMARY BREAST CANCER (MARGIN-II)

Abstract Introduction: The goal of breast conserving surgery (BCS) for early breast cancer (EBC) is to remove the tumor in toto and preserving as much of the normal breast tissue as possible. In 20-50% of cases a re-excision is necessary because of involved margins. Repeat surgeries are not only a burden to patients physically but also psychologically and can delay recommended adjuvant therapies. Accurate determination of tumor margins during surgery is therefore a critical need. Breast cancer tissue produces significantly higher amounts of VEGF-A than healthy tissue. VEGF-A stimulates tumor angiogenesis and is therefore a target for molecular imaging techniques. The fluorescence imaging agent bevacizumab-IRDye800CW (Beva800) is a conjugate of bevacizumab and IRDye800CW and binds specifically to VEGF-A. Beva800 provides a potentially efficacious approach to imaging specimen and cavity margins during BCS. We are presenting a phase II study that combined Beva800 with the SurgVision Explorer Air camera for intraoperative margin assessment during BCS for EBC. Methods: MARGIN II is a multicenter open-label single arm prospective clinical trial aimed at evaluating Beva800 for assessment of tumor margins in women with EBC scheduled for BCS. The study was a within-patient comparison of positive tumor margin rates using BCS standard of care margin assessment compared to intraoperative assessment with 4.5 mg Beva800 and fluorescence imaging with the SurgVision Explorer Air camera. All patients received an i.-v. bolus injection of 4.5 mg of Beva800 three days before surgery. The fluorescent signal was visualized during surgery using NIR fluorescence imaging (700–1000 nm). Standard of care margin assessment was defined as visual inspection, palpation and, in cases of pre-operative wire marking, specimen sonography or mammography. Beva800 efficacy was determined as the number of patients in which a pathology-confirmed positive margin was identified by fluorescence-guided surgery using Beva800 but not by standard of care BCS. Results: 49 patients were included in 5 centers. 4 training cases were only included in the safety analysis, 45 patients were evaluable for the efficacy analysis. 8 patients (17.8%) had involved margins after standard of care BCS, 4 of which were detected by molecular fluorescence intraoperatively resulting in the reduction of patients with positive margins by 50% (95% CI: 15.7%, 84.3%). 4 patients (8.9%; 95% CI: 2.5%, 21.1%) needed a re-excision because of involved margins. In 27 patients (60.0%) the additional molecular fluorescence guided cavity shaving did not change the resection status from positive to negative (false positive). Adverse events were reported by 16 of 49 patients (32.7%), but only 3 (6.1%) were related to Beva800 (syncope, hot flush, hypertensive crisis). One patient experienced a treatment related SAE (hypertensive crisis). No anti-Beva800 antibodies were detected. Conclusion: In our analysis the rate of necessary second operations was reduced by 50% using Beva800 and the SurgVision Explorer Air camera. The safety analysis confirmed the positive safety profile of Beva800 found in previous studies. Molecular fluorescence-guided surgery may have the potential to change the practice of breast conserving surgery by reducing unnecessary re-excisions. Future studies will have to address the high false positive rates. Citation Format: Hans-Christian Kolberg, Carmen Röhm, Angrit Stachs, Florian Schütz, Jens-Uwe Blohmer, Sarah Wetzig, Steffi Hartmann, Jörg Heil, Markus Hahn. MOLECULAR FLUORESCENCE-GUIDED SURGERY USING BEVA800 FOR THE ASSESSMENT OF TUMOR MARGINS DURING BREAST CONSERVING SURGERY OF PATIENTS WITH PRIMARY BREAST CANCER (MARGIN-II) [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P2-14-01.

WBC & THEIR ROLE IN TUMOR MICROENVIRONMENT (TME) OF ORAL SQUAMOUS CELL CARCINOMA-A REVIEW

Oral premalignant lesions (OPLs) that affect approximately 4.5% of the world's population usually precede the occurrence of Oral squamous cell carcinoma. These lesions are now included in oral potentially malignant disorders (OPMD). Majority of OPLs regress, yet, up to 30% of them ultimately progress through increasingly grades of dysplasia &culminate as oral cancer. Therefore, OPLs represent an intermediate phase during the evolution of normal mucosa into malignant tumor, owing to their acquisition of a subset of the genomic alterations from those necessary to develop into Oral Squamous cell Carcinoma(OSCC).(1) In India OSCC is responsible for more than 20% of new malignancies diagnosed every year, being the most prevalent malignancy in the nation. There are several prognostic factors which help to evaluate the risk associated with the OSCC and serve as subsequent treatment guidelines. Increasing evidence has, so far, suggested that inammation may be linked to pathogenesis of oral cancer. Also, the tumor microenvironment is considered a crucial component in the understanding of the biologic behavior of a neoplasm. Leukocytosis is common in patients with progressive oral squamous cell carcinoma, is related with T-classication, lympho-vascular permeation, and recurrence or metastasis, &, therefore could decrease survival. Tumor-related leukocytosis results from hematopoietic colony-stimulating factors and inammatory cytokines from solid tumors. (2,4) One of the new most promising histopathological factor in prognostic evaluation of OSCC is, the density of tumour inltrating lymphocytes (TILs). Different subsets of lymphocytes have different or even opposing functions in the tumor microenvironment. (2,6,7) Neutrophils contribute to cancer progression or regression via multiple mechanisms, including the suppression of cytotoxic as well as helper Tcell responses and the stimulation of tumor angiogenesis.(8) B cells also act as antigen-presenting cells, promote differentiation of Th1 cells and Tcyt cells, and directly kill cancer cells through release of Granzyme B, thus, having a tumor suppressive role. (9) Inltrating eosinophils in the tumor microenvironment (TME), supply direct and indirect mitogenic growth mediators that stimulate proliferation of neoplastic cells, as well as educate other stromal cell types to induce paracrine and juxtacrine mitogenic signaling molecules to support neoplastic growth which also appears true for oral squamous cell carcinomas (OSCCs). (10) The plasmacytoid dendritic cells (pDC), are specically important in cancer immunity as, these cells have been identied in many solid malignant tumors, including those of head and neck & may play a key role in tumor occurrence and development.(9,12) Mast cells have a long life and form a heterogeneous population of cells that seem to have both a positive and negative regulatory effect on the immune system. MCs accumulate into tumor microenvironment by the help of tumor cell-released chemoattractants such as SCF or CCL15 and actively recruit cells of the innate immune system mainly neutrophils, macrophages, and eosinophils and cells of the acquired immune system (B and T cells) to orchestrate antitumor immune responses (13) In cancer tissues, the inltration of macrophages is signicantly increased. Macrophages are recruited to this edge by tumor-derived chemotactic agents and are a major inltrating cell type in the leading edge of a carcinoma.(16) OSCC are highly immunogenic tumors that are often characterized by abundant inltration of immune cells, however, their function & prognostic value vary. (19, 20)

Bulk RNA-Seq Combined with Single-Cell Transcriptome Sequencing Reveals the Possible Mechanisms by Which HDGFL3 Involves in Prostate Cancer Growth and Metastasis.

Based on publicly available transcriptome and single-cell sequencing data, the current study aimed to explore the molecular mechanisms underlying the involvement of hepatocellular carcinoma-derived growth factor-like 3 (HDGFL3) in prostate cancer (PCA) growth and metastasis. The Gene Expression Omnibus database was used to download the single cell transcriptome of PCA (GSE193337). Single-cell RNA sequencing (scRNA-seq) data were examined to identify which genes are essential for endothelial cell function. The Cancer Genome Atlas Prostate Adenocarcinoma database provided the RNA sequencing data, and univariate COX regression analysis was introduced to identify the genes that were associated with the prognosis of patients with PCA. Human PCA cell lines PC-3 and DU145 were used in in vitro cellular studies to test the effect of silencing HDGFL3. The results were validated using Transwell® assay, scratch assay, and cell counting kit-8 assay. To support the role of HDGFL3 in PCA, an in vivo animal model of PCA transplantation tumor in nude mice was established. Quantitative reverse transcription polymerase chain reaction was introduced to measure HDGFL3 messenger ribonucleic acid (mRNA) expression levels in tumor tissues from nude mice, and Hematoxylin and Eosin staining was used to identify lung metastasis. Immunohistochemical staining was employed to identify the expression levels of HDGFL3 and hematopoietic progenitor cell antigen CD34+. It was discovered through analysis of the scRNA-seq dataset that HDGFL3, a gene specific to endothelial cells, is linked to a poor prognosis in men with PCA. In addition, HDGFL3 and the expression of genes linked to angiogenesis have a substantial association. Studies on cells in vitro revealed that silencing HDGFL3 prevented PC-3 and DU145 cells from proliferation, migrating and invading. Silencing HDGFL3 decreased the weight of prostate tumors, the number of lung metastases, and the area occupied by CD34+ vascular endothelial cells, according to in vivo investigations. This study identified HDGFL3 as a key gene in endothelial cells that may stimulate tumor angiogenesis to increase the growth and spread of PCA. These results imply that HDGFL3 may represent a possible target for antiangiogenic therapy in the management of PCA.

Tumor-derived exosomal lincRNA ROR promotes angiogenesis in nasopharyngeal carcinoma

Long intergenic noncoding RNAs (lincRNAs) are expressed aberrantly in several malignancies, including nasopharyngeal carcinoma (NPC), where linc-ROR expression was found to be elevated. Being a hallmark of malignant tumors, angiogenesis has prompted us to investigate the impact of linc-ROR on NPC angiogenesis. This study demonstrates that linc-ROR is substantially expressed in serum exosomes from NPC and can be taken up by HUVECs. Using qRT-PCR, the CCK8 test, the transwell migration assay, the wound healing assay, and the tube formation assay, we demonstrated that linc-ROR increases proliferation, migration, and angiogenesis in vitro. Similar to prior research, our results have shown that linc-ROR can stimulate tumor angiogenesis in the zebrafish model. Thus, the p-AKT/p-VEGFR2 pathway is the mechanism by which linc-ROR affects the aforementioned biological activities. By stimulating angiogenesis, linc-ROR appears to play a significant role in the course of NPC and could account for a therapeutic target.

The choline acetyltransferase inhibitor BW813U inhibits angiogenesis and tumor growth in human lung adenocarcinoma

Angiogenesis refers to the development of new blood vessels from preexisting blood vessels. The angiogenic pathway is essential for the growth and progression of almost every kind of human cancer. Nicotine, the addictive component of tobacco smoke is known to accelerate the growth of human lung tumors by stimulating tumor angiogenesis. The pro‐angiogenic effects of nicotine are mediated by nicotinic acetylcholine receptors (nAChRs). The endogenous ligand for nicotine is the neurotransmitter acetylcholine (ACh). Published reports show that ACh acts as growth factor for human lung cancers. Almost all lung tissues (including fetal lung) express signaling proteins involved in the synthesis, transport of the ACh‐signaling pathway. These include choline acetyl transferase enzyme (ChAT), vesicular acetylcholine transporter (VAChT), acetylcholine esterase (AChE) and choline transporter (ChT). The primary objective of our studies was to determine if disruption of ChAT could inhibit angiogenesis and suppress the growth of human LACs. We used a small molecule inhibitor of ChAT namely BW813U for our studies. BW813U robustly suppressed angiogenesis in Matrigel assays and chicken chorioallantoic membrane (CAM) assays. The administration of BW813U potenetly decreased the growth rate of H838 tumors xenotransplanted in SCID mice. Immunohistochemical staining experiments revealed that the anti‐tumor activity of BW813U was correlated with decrease of CD31 angiogenic biomarker in H813 tumor sections. The anti‐angiogenic activity of BW813U was mediated by the alpha7‐nAChR pathway and involved the nitric oxide pathway. Taken together, our studies show that ChAT antagonists like BW813U may have applications in the treatment of LAC.

LILRB4 promotes tumor metastasis by regulating MDSCs and inhibiting miR-1 family miRNAs

ABSTRACT Myeloid-derived suppressor cells (MDSCs) are a population of immune suppressive cells that are involved in tumor-associated immunosuppression, and dominate tumor progression and metastasis. In this study, we report that the leukocyte immunoglobulin-like receptor subfamily B member 4 (LILRB4, murine ortholog gp49B) orchestrates the polarization of MDSCs to exhibit pro-tumor phenotypes. We found that gp49B deficiency inhibited tumor metastases of cancer cells, and reduced tumor-infiltration of monocytic MDSCs (M-MDSCs) in tumor-bearing mice. Gp49B−/− MDSCs inhibited pro-tumor immune responses, such as activation of Treg cells, promotion of cancer cell migration, and stimulation of tumor angiogenesis. Treatment of wild-type tumor-bearing mice with gp49B−/− M-MDSCs reduced cancer metastasis. Furthermore, gp49B knockout affected plasma exosome composition in terms of increased miR-1 family microRNAs (miRNAs) expression, which correlates with the upregulation of gp49B−/− MDSC-derived anti-tumor miRNAs. Collectively, our findings reveal that LILRB4/gp49B promotes MDSC-mediated tumor metastasis by regulating the M2-polarization of MDSCs and suppressing the secretion of miR-1 family miRNAs, which facilitate tumor migration and invasion. Abbreviations CTLA-4: cytotoxic T-lymphocyte-associated protein-4; FBS: fetal bovine serum; G-MDSCs: granulocytic-MDSCs; GP49B: glycoprotein 49B; HE: hematoxylin-eosin; ICI: immune checkpoint inhibitor; ITIM: immunoreceptor tyrosine-based inhibition motif; LILRB4: leukocyte immunoglobulin-like receptor B4; M-CSF: macrophage colony stimulating factor; MDSC: myeloid-derived suppressor cell; M-MDSC: monocytic MDSC; MMP-9: metallopeptidase-9; mAb: monoclonal antibody; PBS: phosphate-buffered saline; PCR: polymerase chain reaction; PD-1: programmed death-1; PD-L1: programmed death ligand-1; PMN-MDSC: polymorphonuclear-MDSC; qRT-PCR: quantitative reverse transcription PCR; TAM: tumor associated macrophage; TME: tumor microenvironment; TMM: trimmed mean of M value; VEGFA: vascular endothelial growth factor A

Role of macrophages in tumor progression and therapy (Review).

The number and phenotype of macrophages are closely related to tumor growth and prognosis. Macrophages are recruited to (and polarized at) the tumor site thereby promoting tumor growth, stimulating tumor angiogenesis, facilitating tumor cell migration, and creating a favorable environment for subsequent colonization by (and survival of) tumor cells. These phenomena contribute to the formation of an immunosuppressive tumor microenvironment (TME) and therefore speed up tumor cell proliferation and metastasis and reduce the efficacy of antitumor factors and therapies. The ability of macrophages to remodel the TME through interactions with other cells and corresponding changes in their number, activity, and phenotype during conventional therapies, as well as the association between these changes and drug resistance, make tumor-associated macrophages a new target for antitumor therapies. In this review, advantages and limitations of the existing antitumor strategies targeting macrophages in Traditional Chinese and Western medicine were analyzed, starting with the effect of macrophages on tumors and their interactions with other cells and then the role of macrophages in conventional treatments was explored. Possible directions of future developments in this field from an all-around multitarget standpoint were also examined.

Are TEMs Canceled? Questioning the Functional Relevance of Tie2-Expressing Macrophages.

Inflammatory cells are a vital component of the tumor stroma and, of these, tumor-associated macrophages (TAM) are the major cell type. TAMs are recruited early in tumorigenesis and generally promote metastasis, stimulate tumor angiogenesis, and drive immunosuppression. TAMs have been shown to express the endothelial cell markers that enable chemotaxis and proangiogenic capacity. In this issue of Cancer Research, Jakab and colleagues challenge the functional significance of Tie2-expressing monocytes/macrophages (TEM) in the context of tumor growth and progression. By employing myeloid-specific deletion of the angiopoietin receptor Tie2 and comprehensive analysis of myeloid cell single-cell RNA sequencing datasets, they provide compelling data that Tie2-positive macrophages do not contribute to tumor angiogenesis or relapse after chemotherapy, two major biologic processes previously attributed to tumor-associated TEMs. The study highlights that the concept of macrophage-expressed Tie2 as a therapeutic target or prognostic indicator needs reconsideration. See related article by Jakab et al., p. 1353.

Engineering tumor constructs to study matrix-dependent angiogenic signaling of breast cancer cells.

Breast cancer is the leading cause of cancer deaths among females globally. The crosstalk between tumor microenvironment and neoplastic cells is the key for promoting tumor growth, stimulating tumor angiogenesis, and metastasis to distant organs. Thus, it is highly important to investigate tumor cell-matrix interactions to facilitate screening of different anti-cancer agents, individually or in combination. We, herein report, the development of an in vitro three-dimensional (3D) breast cancer model to investigate the effect of stromal crosslinking and consequent, stiffening on the angiogenic activity of cancer cells. Crosslinking of collagen gels was altered via non-enzymatic glycation and highly aggressive breast cancer cells, MDA-MB-231, were encapsulated in these gels. Cells encapsulated in glycated/stiffer matrices displayed an increased expression of pro-angiogenesis-related signals. Inhibition of mechanotransduction pathways on the angiogenic activity of aggressive tumor cells in stiff matrices was investigated using Y-27632, blebbistatin, and cytochalasin D. Rho-associated kinase (ROCK) inhibitor, Y-27632, diminished the pro-angiogenic signaling, thereby suggesting the potential dependence of breast cancer cells on the Rho/ROCK pathway in regulating tumor angiogenesis. Our findings highlight the potential of the developed model to be used as a tool to investigate matrix-associated tumor angiogenesis and screen different therapeutic agents towards inhibiting it.

Advances in the Study of Tumor-associated Macrophages in Lung Cancer

肺癌是全球发病率和死亡率最高的恶性肿瘤之一。因此对于肺癌治疗手段的研究也在不断深入，目前临床上主要有全身化疗、针对驱动基因阳性的靶向治疗、免疫检查点抑制剂的应用、抗肿瘤血管生成治疗以及上述不同治疗方法的联合等，这些方案的使用明显改善了大多数肺癌患者的预后，但晚期患者预后仍然不尽如人意。近年来，与免疫相关的肿瘤微环境（tumor microenvironment, TME）的研究越来越受到重视。TME由免疫细胞、成纤维细胞、血管内皮细胞等细胞成分及相关的细胞因子等组成，是肿瘤细胞赖以生存、发展的基础。而肿瘤相关巨噬细胞（tumor-associated macrophages, TAMs）是TME重要的免疫细胞，指浸润于肿瘤组织中的巨噬细胞，可促进肿瘤细胞增殖，诱导肿瘤免疫耐受，刺激肿瘤血管生成，增加肿瘤细胞的侵袭及转移能力。因此，靶向TAMs已经成为肺癌免疫治疗的热点。本文就TAMs来源、表型及其在肺癌中的作用机制以及在未来治疗中的靶点进行综述，为肺癌最优化治疗提供参考。

SIRT1-mediated deacetylation of FOXO3a transcription factor supports pro-angiogenic activity of interferon-deficient tumor-associated neutrophils.

Angiogenesis plays an important role during tumor growth and metastasis. We could previously show that Type I interferon (IFN)-deficient tumor-associated neutrophils (TANs) show strong pro-angiogenic activity, and stimulate tumor angiogenesis and growth. However, the exact mechanism responsible for their pro-angiogenic shift is not clear. Here, we set out to delineate the molecular mechanism and factors regulating pro-angiogenic properties of neutrophils in the context of Type I IFN availability. We demonstrate that neutrophils from IFN-deficient (Ifnar1-/- ) mice efficiently release pro-angiogenic factors, such as VEGF, MMP9 or BV8, and thus significantly support the vascular normalization of tumors by increasing the maturation of perivascular cells. Mechanistically, we could show here that the expression of pro-angiogenic factors in neutrophils is controlled by the transcription factor forkhead box protein O3a (FOXO3a), which activity depends on its post-translational modifications, such as deacetylation or phosphorylation. In TANs isolated from Ifnar1-/- mice, we observe significantly elevated SIRT1, resulting in SIRT1-mediated deacetylation of FOXO3a, its nuclear retention and activation. Activated FOXO3a supports in turn the transcription of pro-angiogenic genes in TANs. In the absence of SIRT1, or after its inhibition in neutrophils, elevated kinase MEK/ERK and PI3K/AKT activity is observed, leading to FOXO3a phosphorylation, cytoplasmic transfer and inactivation. In summary, we have found that FOXO3a is a key transcription factor controlling the angiogenic switch of neutrophils. Post-translational FOXO3a modifications regulate its transcriptional activity and, as a result, the expression of pro-angiogenic factors supporting development of vascular network in growing tumors. Therefore, targeting FOXO3a activity could provide a novel strategy of antiangiogenic targeted therapy for cancer.

Novel Characterization of Myeloid-Derived Suppressor Cells in Tumor Microenvironment.

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous group of cells generated in various pathologic conditions, which have been known to be key components of the tumor microenvironment (TME) involving in tumor immune tolerance. So MDSCs have been extensively researched recently. As its name suggests, immunosuppression is the widely accepted function of MDSCs. Aside from suppressing antitumor immune responses, MDSCs in the TME also stimulate tumor angiogenesis and metastasis, thereby promoting tumor growth and development. Therefore, altering the recruitment, expansion, activation, and immunosuppression of MDSCs could partially restore antitumor immunity. So, this view focused on the favorable TME conditions that promote the immunosuppressive effects of MDSCs and contribute to targeted therapies with increased precision for MDSCs.

Abstract 2720: Perivascular accumulation of immunosuppressive cells in the stroma of human triple negative breast carcinomas: implications for immunotherapy

Abstract A distinct subset of tumor-associated macrophages (TAMs) accumulate around blood vessels in mouse tumors where they stimulate tumor angiogenesis and various steps in the metastatic pathway. They also limit tumor responses to frontline anti-cancer therapies like irradiation and chemotherapy, and dampen anti-tumor immunity by recruiting regulatory T cells and suppressing the proliferation of T cells. However, the presence and phenotype of such perivascular (PV) TAMs have yet to be investigated in human tumors. In this study we have used MultiOmyx multiplex immunofluorescence coupled to advanced analytics to compare the distribution and phenotype of TAMs, CD4+ and CD8+ T cells, and CD4+FOXP3+ regulatory T cells (Tregs) in PV vs non-PV areas in the stroma and tumor cell islands (TCIs) of 40 human triple negative breast carcinomas (TNBCs) - and whether this was altered after neoadjuvant chemotherapy. Tregs along with distinct subsets of TAMs and CD4+ and CD8+ T cells were found to preferentially accumulate in PV areas (ie. within 50um of CD31+ blood vessels), especially in the tumor stroma. CD163+ TIM3+ TAMs often made direct contact with the abluminal surface of blood vessels in these sites, and at increased numbers in in chemotherapy-treated TNBCs. This suggests they may regulate the formation/function of blood vessels in relapsing tumors. In both untreated and chemotherapy-treated tumors, a major subset of CD163+ TAMs lacked PDL1 expression and also accumulated preferentially in stromal PV areas, where many made direct contact with PD1- CD4+ or PD1- CD8+ T cells as well as FOXP3+CD4+ Tregs. We are currently investigating whether such close contact of these subsets of T cells with two immunosuppressive cell types (ie. CD163+ TAMs and Tregs) inhibits their subsequent anti-tumor functions. Taken together, our study shows that, as T cells cross blood vessels into TNBCs, they encounter a high density of at least two immunosuppressive cell types in the perivascular niche. This could lead to the inactivation of T cells before they migrate further into tumors, thereby reducing anti-tumor immunity. It could also limit the efficacy of cancer immunotherapies mediated by activated T cells. Identifying and targeting the mechanism causing these suppressive cells to accumulate and interact in such sites could remove this inhibition. Citation Format: Mohammed Ridha Moamin, Richard J. Allen, Nicholas Stavrou, Mate Nagy, Anna Juncker-Jensen, Claire E. Lewis. Perivascular accumulation of immunosuppressive cells in the stroma of human triple negative breast carcinomas: implications for immunotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2720.

Targeting HIF-1α by newly synthesized Indolephenoxyacetamide (IPA) analogs to induce anti-angiogenesis-mediated solid tumor suppression.

Hypoxic microenvironment is a common feature of solid tumors, which leads to the promotion of cancer. The transcription factor, HIF-1α, expressed under hypoxic conditions stimulates tumor angiogenesis, favoring HIF-1α as a promising anticancer agent. On the other hand, synthetic Indolephenoxyacetamide derivatives are known for their pharmacological potentiality. With this background here, we have synthesized, characterized, and validated the new IPA (8a-n) analogs for anti-tumor activity. The new series of IPA (8a-n) were synthesized through a multi-step reaction sequence and characterized based on the different spectroscopic analysis FT-IR, 1H, 13C NMR, mass spectra, and elemental analyses. Cell-based screening of IPA (8a-n) was assessed by MTT assay. Anti-angiogenic efficacy of IPA (8k) validated through CAM, Rat corneal, tube formation and migration assay. The underlying molecular mechanism is validated through zymogram and IB studies. The in vivo anti-tumor activity was measured in the DLA solid tumor model. Screening for anti-proliferative studies inferred, IPA (8k) is a lead molecule with an IC50 value of ˜5μM. Anti-angiogenic assays revealed the angiopreventive activity through inhibition of HIF-1α and modulation downstream regulatory genes, VEGF, MMPs, and P53. The results are confirmative in an in vivo solid tumor model. The IPA (8k) is a potent anti-proliferative molecule with anti-angiogenic activity and specifically targets HIF1α, thereby modulates its downstream regulatory genes both in vitro and in vivo. The study provides scope for new target-specific drug development against HIF-1α for the treatment of solid tumors.

Abstract PS1-21: Molecular fluorescence-guided surgery using Beva800 for the assessment of tumor margins during breast conserving surgery of patients with primary breast cancer (MARGIN-II)

Abstract Introduction:The goal of breast conserving surgery (BCS) for early breast cancer (EBC) is to remove the tumor and a surrounding rim of normal tissue, while preserving as much of the normal breast tissue as possible. Incomplete resections are associated with higher rates of surgical re-excision. Repeat surgeries are not only a burden to patients physically but also psychologically and can delay recommended adjuvant therapies. Accurate determination of tumor margins during surgery is therefore critical for successful outcome. Breast cancer tissue produces significantly higher amounts of VEGF-A than healthy tissue. VEGF-A stimulates tumor angiogenesis and is therefore an excellent target for molecular imaging techniques. The fluorescence imaging agent bevacizumab-IRDye800CW (Beva800) is a conjugate of bevacizumab (a humanized antibody targeting human VEGF) and IRDye800CW (a near-infrared fluorescence dye) which binds specifically to VEGF-A. Beva800 provides a potentially highly efficacious approach to imaging specimen and cavity margins during BCS. Herein we present a phase II study that combined Beva800 with the SurgVision Explorer Air camera for intraoperative margin assessment during BCS for EBC.Methods:MARGIN II is a multicenter open-label single arm prospective clinical trial aimed at evaluating Beva800 for assessment of tumor margins in women with EBC scheduled for BCS. The study was a within-patient comparison of positive tumor margin rates using BCS standard of care compared to intraoperative assessment with 4.5 mg Beva800 and fluorescence imaging with the SurgVision Explorer Air camera. Patients undergoing neoadjuvant chemotherapy were excluded. All patients received a single intra-venous bolus injection of 4.5 mg of Beva800 three days before surgery. The fluorescent signal was visualized during surgery using NIR fluorescence imaging (700-1000 nm). This wavelength window typically has very low tissue auto-fluorescence (filtering out background noise) and greater tissue penetration depth due to reduced haemoglobin absorption. Standard of care assessment was defined as visual inspection, palpation and, in cases of pre-operative wire marking, specimen sonography or mammography. Beva800 efficacy was determined as the number of patients in which a pathology-confirmed positive margin was identified by fluorescence guided surgery using Beva800 but not by standard of care BCS. The results per patient were divided into two clusters: results after standard of care BCS and results after fluorescence guided surgery, according to their margin status at pathology. The need for re-operation because of involved margins within 30 days after the first BCS and the safety of 4.5 mg Beva800 was assessed.Results:The recruitment goal of 40 patients in 5 centers has almost been reached and results of the final analysis will be presented at the meeting.Conclusion:Molecular fluorescence-guided surgery using Beva800 has the potential to change the practice of breast conserving surgery by avoiding unnecessary re-operations. This would lead to fewer interventions, a reduced burden on patients through repeat surgery and reduced delay of adjuvant therapies. Citation Format: Hans-Christian Kolberg, Carmen Röhm, Angrit Stachs, Florian Schütz, Jens-Uwe Blohmer, Sarah Wetzig, Steffi Hartmann, Jörg Heil, Markus Hahn. Molecular fluorescence-guided surgery using Beva800 for the assessment of tumor margins during breast conserving surgery of patients with primary breast cancer (MARGIN-II) [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS1-21.

The Stemness-High Human Colorectal Cancer Cells Promote Angiogenesis by Producing Higher Amounts of Angiogenic Cytokines via Activation of the Egfr/Akt/Nf-κB Pathway.

Purpose: Cancer stem cells (CSCs) are responsible for cancer metastasis by stimulating tumor angiogenesis via various mechanisms. To elucidate the potential of the stemness-high human colorectal cancer (CRC) cells (i.e., CRCSCs) in activating angiogenesis, effects of the GATA6-overexpressing HCT-116 and HT-29 human CRC clones established previously by us in promoting the angiogenesis of human umbilical vein endothelial cells (HUVECs) were examined. Methods: Angiogenesis-promoting effects (i.e., migration, invasion, DNA synthesis, and tube formation) in HUVECs of the conditioned media (CM) from various human CRC clones were analyzed. MMP activities were assessed using a zymography assay. Western blotting and selective inhibitors were used to dissect the signaling pathway involved. IHC was used to examine the vascular density in tumor xenografts. Results: We found that the conditioned media (CM) collected from the GATA6-overexpressing clones enhanced angiogenesis of HUVECs more effectively which might be attributed partly to a higher MMP-9 production by HUVECs. Subsequently, elevated levels of IL-8 and VEGF-A were detected in the CM whose tube formation-enhancing activities were abolished by the co-treatment with either a VEGFR2 inhibitor or an IL-8 neutralizing antibody. Interestingly, increased production of these cytokines in the GATA6-overexpressing clones was due to an EGFR/AKT-mediated activation of NF-κB. Furthermore, not only were the levels of CD31 and endomucin but also the blood vessel density was much higher in the xenograft tumors grown from these clones. Conclusion: Our findings demonstrate that human CRCSCs promote a stronger angiogenesis by producing higher amounts of angiogenic factors through activation of the EGFR/AKT/NF-κB pathway.

Tie-2-expressing monocytes in hepatitis C virus-related hepatocellular carcinoma

Background Angiogenesis is a critical step in the development and progression of hepatocellular carcinoma (HCC). Tie-2-expressing monocytes (TEMs) with proangiogenic activity are recruited to the tumor site where they stimulate tumor angiogenesis. Objective This study aimed to assess the role of TEMs in diagnosis of hepatitis C virus (HCV)-related HCC. Patients and methods The study was conducted on 50 patients diagnosed with HCC and HCV. Patients were categorized into two groups: one included patients with HCC (n=25) and the other included HCV-infected patients (n=25). Moreover, 25 age-matched and sex-matched healthy individuals were recruited as a control group. The frequency of TEMs, as defined as CD14+CD16+Tie-2+ cells, in the peripheral blood was determined by flow cytometry. Results The frequency of TEMs in peripheral blood (PB) monocytes was significantly higher in HCC group (53.1±18.2%) than in patients with HCV (27.3±13.9%) and controls (8.4±3.9%). The percentage of TEMs correlates with advanced Child-Pugh stage in patients with HCC and HCV infection (P<0.01). Upon performing receiver operating characteristics curve analysis, a cutoff point of 33% for TEMs was able to differentiate patients with HCC from HCV-infected patients. Regarding differentiating patients with HCC from healthy participants, the cutoff value of 33.8% yielded 88% sensitivity and 100% specificity. The diagnostic performance of combination of TEMs and α-fetoprotein was also assessed, with 98% sensitivity and 100% specificity. Conclusion Percentage of TEMs in PB monocytes may be applied as a complementary biomarker for identifying HCV-related HCC along with α-fetoprotein. Inhibiting the proangiogenic functions of TEMs may represent a promising strategy to improve the efficacy of current treatments for HCC.