Antiangiogenesis in haematological malignancies

Cancer-Associated Angiogenesis: The Endothelial Cell as a Checkpoint for Immunological Patrolling

Simple Summary

A clinical decision and study design investigating the level and extent of angiogenesis modulation aimed at vascular normalization without rendering tissues hypoxic is key and represents an unmet medical need. Specifically, determining the active concentration and optimal times of the administration of antiangiogenetic drugs is crucial to inhibit the growth of any microscopic residual tumor after surgical resection and in the pre-malignant and smolder neoplastic state. This review uncovers the pre-clinical translational insights crucial to overcome the caveats faced so far while employing anti-angiogenesis. This literature revision also explores how abnormalities in the tumor endothelium harm the crosstalk with an effective immune cell response, envisioning a novel combination with other anti-cancer drugs and immunomodulatory agents. These insights hold vast potential to both repress tumorigenesis and unleash an effective immune response.

Abstract

Cancer-associated neo vessels’ formation acts as a gatekeeper that orchestrates the entrance and egress of patrolling immune cells within the tumor milieu. This is achieved, in part, via the directed chemokines’ expression and cell adhesion molecules on the endothelial cell surface that attract and retain circulating leukocytes. The crosstalk between adaptive immune cells and the cancer endothelium is thus essential for tumor immune surveillance and the success of immune-based therapies that harness immune cells to kill tumor cells. This review will focus on the biology of the endothelium and will explore the vascular-specific molecular mediators that control the recruitment, retention, and trafficking of immune cells that are essential for effective antitumor immunity. The literature revision will also explore how abnormalities in the tumor endothelium impair crosstalk with adaptive immune cells and how targeting these abnormalities can improve the success of immune-based therapies for different malignancies, with a particular focus on the paradigmatic example represented by multiple myeloma. We also generated and provide two original bio-informatic analyses, in order to sketch the physiopathology underlying the endothelial–neoplastic interactions in an easier manner, feeding into a vicious cycle propagating disease progression and highlighting novel pathways that might be exploited therapeutically.

Anti-angiogenesis and Immunotherapy: Novel Paradigms to Envision Tailored Approaches in Renal Cell-Carcinoma

Although decision making strategy based on clinico-histopathological criteria is well established, renal cell carcinoma (RCC) represents a spectrum of biological ecosystems characterized by distinct genetic and molecular alterations, diverse clinical courses and potential specific therapeutic vulnerabilities. Given the plethora of drugs available, the subtype-tailored treatment to RCC subtype holds the potential to improve patient outcome, shrinking treatment-related morbidity and cost. The emerging knowledge of the molecular taxonomy of RCC is evolving, whilst the antiangiogenic and immunotherapy landscape maintains and reinforces their potential. Although several prognostic factors of survival in patients with RCC have been described, no reliable predictive biomarkers of treatment individual sensitivity or resistance have been identified. In this review, we summarize the available evidence able to prompt more precise and individualized patient selection in well-designed clinical trials, covering the unmet need of medical choices in the era of next-generation anti-angiogenesis and immunotherapy.

Redistribution, homing and organ-invasion of neoplastic stem cells in myeloid neoplasms

The development of a myeloid neoplasm is a step-wise process that originates from leukemic stem cells (LSC) and includes pre-leukemic stages, overt leukemia and a drug-resistant terminal phase. Organ-invasion may occur in any stage, but is usually associated with advanced disease and a poor prognosis. Sometimes, extra-medullary organ invasion shows a metastasis-like or even sarcoma-like destructive growth of neoplastic cells in local tissue sites. Examples are myeloid sarcoma, mast cell sarcoma and localized blast phase of chronic myeloid leukemia. So far, little is known about mechanisms underlying re-distribution and extramedullary dissemination of LSC in myeloid neoplasms. In this article, we discuss mechanisms through which LSC can mobilize out of the bone marrow niche, can transmigrate from the blood stream into extramedullary organs, can invade local tissue sites and can potentially create or support the formation of local stem cell niches. In addition, we discuss strategies to interfere with LSC expansion and organ invasion by targeted drug therapies.

Olaptesed pegol (NOX-A12) with bendamustine and rituximab: a phase IIa study in patients with relapsed/refractory chronic lymphocytic leukemia

Olaptesed pegol (NOX-A12) is a pegylated structured L-oligoribonucleotide that binds and neutralizes CXCL12, a chemokine tightly regulating the life cycle of chronic lymphocytic leukemia cells. The resulting inhibition of CXCR4 and CXCR7 signaling reduces the protective activity of the bone marrow and lymph node microenvironment. CXCL12 inhibition mobilizes chronic lymphocytic leukemia cells into the circulation and prevents their homing into the protective niches. In this phase I/II study, 28 patients with relapsed/refractory chronic lymphocytic leukemia were treated with olaptesed pegol in combination with bendamustine and rituximab. Combination treatment was preceded by single escalating pilot doses of olaptesed pegol in the first ten patients for evaluation of safety and pharmacokinetics. Peak concentrations and systemic exposure of olaptesed pegol were dose-linear; plasma elimination was monophasic with a 53.2 h half-life. A rapid increase in circulating chronic lymphocytic leukemia cells was observed already 1 h after administration of olaptesed pegol and lasted for at least 72 h. Single-agent treatment was well tolerated and no dose-limiting toxicity was observed. The combination regimen yielded an overall response rate of 86%, with 11% of patients achieving a complete response and 75% a partial response. Notably, all ten high-risk patients, including four with a 17p deletion, responded to treatment. The median progression-free survival was 15.4 (95% confidence interval: 12.2, 26.2) months while the median overall survival was not reached with >80% of patients alive after a median follow-up of 28 months. Olaptesed pegol was well tolerated and did not result in additional toxicity when combined with bendamustine and rituximab (ClinicalTrials.gov identifier: NCT01486797). Further clinical development of this novel CXCL12 inhibitor is thus warranted.

Immunogenicity moderation effect of interleukin-24 on myelogenous leukemia cells

Previous studies have shown that interleukin-24 (IL-24) has tumor-suppressing activity by multiple pathways. However, the immunogenicity moderation effect of IL-24 on malignant cells has not been explored extensively. In this study, we investigated the role of IL-24 in immunogenicity modulation of the myelogenous leukemia cells. Data show that myelogenous leukemia cells express low levels of immunogenicity molecules. Treatment with IL-24 could enhance leukemia cell immunogenicity, predominantly regulate leukemia cells to produce immune-associated cytokines, and improve the cytotoxic sensitivity of these cells to immune effector cells. IL-24 expression could retard transplanted leukemia cell tumor growth in vivo in athymic nude mice. Moreover, IL-24 had marked effects on downregulating the expression of angiogenesis-related proteins vascular endothelial growth factor, cluster of differentiation (CD) 31, CD34, collagen IV and metastasis-related factors CD147, membrane type-1 matrix metalloproteinase (MMP), and MMP-2 and MMP-9 in transplanted tumors. These findings indicated novel functions of this antitumor gene and characterized IL-24 as a promising agent for further clinical trial for hematologic malignancy immunotherapy.

Inhibition of Siah2 Ubiquitin Ligase by Vitamin K3 Attenuates Chronic Myeloid Leukemia Chemo-Resistance in Hypoxic Microenvironment

BACKGROUND A hypoxic microenvironment is associated with resistance to tyrosine kinase inhibitors (TKIs) and a poor prognosis in chronic myeloid leukemia (CML). The E3 ubiquitin ligase Siah2 plays a vital role in the regulation of hypoxia response, as well as in leukemogenesis. However, the role of Siah2 in CML resistance is unclear, and it is unknown whether vitaminK3 (a Siah2 inhibitor) can improve the chemo-sensitivity of CML cells in a hypoxic microenvironment. MATERIAL AND METHODS The expression of Siah2 was detected in CML patients (CML-CP and CML-BC), K562 cells, and K562-imatinib-resistant cells (K562-R cells). We measured the expression of PHD3, HIF-1α, and VEGF in both cell lines under normoxia and hypoxic conditions, and the degree of leukemic sensitivity to imatinib and VitaminK3 were evaluated. RESULTS Siah2 was overexpressed in CML-BC patients (n=9) as compared to CML-CP patients (n=13). Similarly, K562-imatinib-resistant cells (K562-R cells) showed a significantly higher expression of Siah2 as compared to K562 cells in a hypoxic microenvironment. Compared to normoxia, under hypoxic conditions, both cell lines had lower PHD3, higher HIF-1α, and higher VEGF expression. Additionally, Vitamin K3 (an inhibitor of Siah2) reversed these changes and promoted a higher degree of leukemic sensitivity to imatinib. CONCLUSIONS Our findings indicate that the Siah2-PHD3- HIF-1α-VEGF axis is an important hypoxic signaling pathway in a leukemic microenvironment. An inhibitor of Siah2, combined with TKIs, might be a promising therapy for relapsing and refractory CML patients.

Necl 4 and RNase 5 Are Important Biomarkers for Gastric and Colon Adenocarcinomas

BACKGROUND There is a need to identify new prognostic factors that may be used in addition to the known risk factors in gastrointestinal adenocarcinomas. In this study, we aimed to determine the expression of Necl 4 and RNase 5 biomarkers in gastric and colon adenocarcinomas, as well as the prognostic efficacy of these biomarkers in gastric and colon adenocarcinomas. MATERIAL AND METHODS Ninety-two cases resected due to stomach and colon adenocarcinoma were included in the study. The expression of Necl 4 and RNase 5 biomarkers was evaluated by immunohistochemical staining of the stomach and colon normal mucosa and adenocarcinoma areas. RESULTS In colon adenocarcinomas, there was a significant association between Necl 4 and lymphovascular invasion, vascular invasion, and perineural invasion (p<0.05). There was a significant association between RNase 5 and histological differentiation in colon adenocarcinomas (p<0.05). There was no association between RNase 5 and Necl 4 in gastric or colon adenocarcinomas. CONCLUSIONS Necl 4 may have prognostic value in colon adenocarcinomas, but it is difficult to ascertain in gastric adenocarcinomas.

Angiogenesis in JAK2 V617F positive myeloproliferative neoplasms and ruxolitinib decrease VEGF, HIF-1 enesis in JAK2 V617F positive cells

Angiogenesis and JAK2 V617F mutation are common in BCR-ABL1 negative myeloproliferative neoplasms (MPNs). Ruxolitinib, a JAK inhibitor, is an effective treatment for some MPNs. However, the relationship between angiogenesis and JAK2 V617F and the effects of ruxolitinib on angiogenesis are still unknown. Here, we observed the correlation of JAK2 V617F mutation burden with VEGF, HIF-1a and microvascular density (MVD) in MPNs. We investigate the effect of ruxolitinib on the expression of VEGF and HIF-1α in JAK2 V617F positive cells. We found the expression levels of p-JAK2, VEGF, HIF-1a and MVD in the newly diagnosed MPNs were significantly increased and were related to the JAK2 V617F burden. Ruxolitinib can inhibit p-JAK2, VEGF, HIF-1a expression and suppress blood vessels' formation in chick embryo choriallantoic membrane. Our findings indicated that angiogenesis is related to JAK2 V617F burden and ruxolitinib could decrease VEGF and HIF-1a expression in JAK2 V617F positive cells.

Placental growth factor: What hematologists need to know

Although first identified in placenta, the angiogenic factor known as placental growth factor (PlGF) can be widely expressed in ischemic or damaged tissues. Recent studies have indicated that PlGF is a relevant factor in the pathobiology of blood diseases including hemoglobinopathies and hematologic malignancies. Therapies for such blood diseases may one day be based upon these and ongoing investigations into the role of PlGF in sickle cell disease, acute and chronic leukemias, and complications related to hematopoietic cell transplantation. In this review, we summarize recent studies regarding the potential role of PlGF in blood disorders and suggest avenues for future research.

In Vitro and In Vivo Effects of Tumor Suppressor Gene PTEN on Endometriosis: An Experimental Study

BACKGROUND Endometriosis can cause dysmenorrhea and infertility. Its pathogenesis has not yet been clarified and its treatment continues to pose enormous challenges. The protein tyrosine phosphatase (PTEN) gene is a tumor suppressor gene. The aim of this study was to investigate the role and significance of PTEN protein in the occurrence, development, and treatment of endometriosis through changes in apoptosis rate, cell cycle, and angiogenesis. MATERIAL AND METHODS PTEN was overexpressed and silenced in lentiviral vectors and inserted into primary endometrial cells. The changes in cell cycle and apoptosis in the different PTEN expression groups were evaluated using flow cytometry. Vessel growth mimicry was observed using 3-dimensional culture. A human-mouse chimeric endometriosis model was constructed using SCID mice. Hematoxylin and eosin staining and immunohistochemistry were used to detect pathological changes in ectopic endometrial tissues and the expression of VEGF protein in a human-mouse chimeric endometriosis mouse model. RESULTS PTEN overexpression significantly increased apoptosis and inhibited the cell cycle compared with the silenced and control groups. Furthermore, cells expressing low PTEN levels were better able to undergo vasculogenic mimicry, and exhibited significantly increased angiogenesis compared to cells overexpressing PTEN. We found that ectopic foci were more easily formed in the endometrial tissue of SCID mice with low PTEN expression, and the VEGF expression in this group was relatively high. CONCLUSIONS PTEN inhibits the occurrence and development of endometriosis by regulating angiogenesis and the apoptosis and cell cycle of endometrial cells; therefore, we propose that the PTEN gene can be used to treat endometriosis.

Monoclonal antibody therapy in multiple myeloma: where do we stand and where are we going?

Multiple myeloma is a plasma cell malignancy that is characterized by refractory and relapsing course of disease. Despite the introduction of high-dose chemotherapy in combination with autologous stem cell transplantation and innovative agents such as proteasome inhibitors and immunomodulatory drugs, achieving cure in multiple myeloma is a challenging endeavor. In the last couple of years, enormous advances were made in implementing monoclonal antibody therapy in multiple myeloma. A large number of preclinical and clinical studies have been introduced successfully, demonstrating a safe and efficient administration of monoclonal antibodies in multiple myeloma. In particular, the application of monoclonal antibodies in combination with immunomodulatory drugs, proteasome inhibitors, corticosteroids or conventional chemotherapy seem to be promising and will expand the treatment arsenal for patients with multiple myeloma.

Antiangiogenic mechanisms and factors in breast cancer treatment

Breast cancer is known to metastasize in its latter stages of existence. The different angiogenic mechanisms and factors that allow for its progression are reviewed in this article. Understanding these mechanisms and factors will allow researchers to design drugs to inhibit angiogenic behaviors and control the rate of tumor growth.

Hypoxia-induced retinal neovascularization in zebrafish embryos: a potential model of retinopathy of prematurity

Retinopathy of prematurity, formerly known as a retrolental fibroplasia, is a leading cause of infantile blindness worldwide. Retinopathy of prematurity is caused by the failure of central retinal vessels to reach the retinal periphery, creating a nonperfused peripheral retina, resulting in retinal hypoxia, neovascularization, vitreous hemorrhage, vitreoretinal fibrosis, and loss of vision. We established a potential retinopathy of prematurity model by using a green fluorescent vascular endothelium zebrafish transgenic line treated with cobalt chloride (a hypoxia-inducing agent), followed by GS4012 (a vascular endothelial growth factor inducer) at 24 hours postfertilization, and observed that the number of vascular branches and sprouts significantly increased in the central retinal vascular trunks 2-4 days after treatment. We created an angiography method by using tetramethylrhodamine dextran, which exhibited severe vascular leakage through the vessel wall into the surrounding retinal tissues. The quantification of mRNA extracted from the heads of the larvae by using real-time quantitative polymerase chain reaction revealed a twofold increase in vegfaa and vegfr2 expression compared with the control group, indicating increased vascular endothelial growth factor signaling in the hypoxic condition. In addition, we demonstrated that the hypoxic insult could be effectively rescued by several antivascular endothelial growth factor agents such as SU5416, bevacizumab, and ranibizumab. In conclusion, we provide a simple, highly reproducible, and clinically relevant retinopathy of prematurity model based on zebrafish embryos; this model may serve as a useful platform for clarifying the mechanisms of human retinopathy of prematurity and its progression.

Isoindolone derivative QSN-10c induces leukemic cell apoptosis and suppresses angiogenesis via PI3K/AKT signaling pathway inhibition

AIM

2-(4,6-Dimethoxy-1,3-dioxoisoindolin-2-yl) ethyl 2-chloroacetate (QSN-10c) is one of isoindolone derivatives with antiproliferative activity against human umbilical vein endothelial cells (HUVECs). The aim of this study was to investigate its antitumor activity in vitro and anti-angiogenic effects in vitro and in vivo.

METHODS

K562 leukemic cells and HUVECs were used for in vitro studies. Cell viability was examined using MTT assay. Cell apoptosis and mitochondrial transmembrane potential (Δψm) were detected with flow cytometry. Tube formation and migration of HUVECs were studied using two-dimensional Matrigel assay and wound-healing migration assay, respectively. VEGF levels were analyzed with RT-PCR and Western blotting. A zebrafish embryo model was used for in vivo anti-angiogenic studies. The molecular mechanisms for apoptosis in K562 cells and antiangiogenesis were measured with Western blotting.

RESULTS

In antitumor activity studies, QSN-10c suppressed the viability of K562 cells and induced apoptosis in dose- and time-dependent manners. Furthermore, QSN-10c dose-dependently decreased the Δψm in K562 cells, increased the release of cytochrome c and the level of Bax, and decreased the level of Bcl-2, suggesting that QSN-10c-induced apoptosis of K562 cells was mediated via the mitochondrial apoptotic pathway. In anti-angiogenic activity studies, QSN-10c suppressed the viability of HUVECs and induced apoptosis in dose dependent manners. QSN-10c treatment did not alter the Δψm in HUVECs, but dose-dependently inhibited the expression of VEGF, inhibited the tube formation and cell migration in vitro, and significantly suppressed the number of ISVs in zebrafish embryos in vivo. Furthermore, QSN-10c dose-dependently suppressed the phosphorylation of AKT and GSK3β in both HUVECs and K562 cells.

CONCLUSION

QSN-10c is a novel antitumor compound that exerts both antitumor and anti-angiogenic effects via inhibiting the PI3K/AKT/GSK3β signaling pathway.

Role of plasma membrane caveolae/lipid rafts in VEGF-induced redox signaling in human leukemia cells

Caveolae/lipid rafts are membrane-rich cholesterol domains endowed with several functions in signal transduction and caveolin-1 (Cav-1) has been reported to be implicated in regulating multiple cancer-associated processes, ranging from tumor growth to multidrug resistance and angiogenesis. Vascular endothelial growth factor receptor-2 (VEGFR-2) and Cav-1 are frequently colocalized, suggesting an important role played by this interaction on cancer cell survival and proliferation. Thus, our attention was directed to a leukemia cell line (B1647) that constitutively produces VEGF and expresses the tyrosine-kinase receptor VEGFR-2. We investigated the presence of VEGFR-2 in caveolae/lipid rafts, focusing on the correlation between reactive oxygen species (ROS) production and glucose transport modulation induced by VEGF, peculiar features of tumor proliferation. In order to better understand the involvement of VEGF/VEGFR-2 in the redox signal transduction, we evaluated the effect of different compounds able to inhibit VEGF interaction with its receptor by different mechanisms, corroborating the obtained results by immunoprecipitation and fluorescence techniques. Results here reported showed that, in B1647 leukemia cells, VEGFR-2 is present in caveolae through association with Cav-1, demonstrating that caveolae/lipid rafts act as platforms for negative modulation of VEGF redox signal transduction cascades leading to glucose uptake and cell proliferation, suggesting therefore novel potential targets.

Synaptojanin-2 binding protein stabilizes the Notch ligands DLL1 and DLL4 and inhibits sprouting angiogenesis

RATIONALE

The formation of novel blood vessels is initiated by vascular endothelial growth factor. Subsequently, DLL4-Notch signaling controls the selection of tip cells, which guide new sprouts, and trailing stalk cells. Notch signaling in stalk cells is induced by DLL4 on the tip cells. Moreover, DLL4 and DLL1 are expressed in the stalk cell plexus to maintain Notch signaling. Notch loss-of-function causes formation of a hyperdense vascular network with disturbed blood flow.

OBJECTIVE

This study was aimed at identifying novel modifiers of Notch signaling that interact with the intracellular domains of DLL1 and DLL4.

METHODS AND RESULTS

Synaptojanin-2 binding protein (SYNJ2BP, also known as ARIP2) interacted with the PDZ binding motif of DLL1 and DLL4, but not with the Notch ligand Jagged-1. SYNJ2BP was preferentially expressed in stalk cells, enhanced DLL1 and DLL4 protein stability, and promoted Notch signaling in endothelial cells. SYNJ2BP induced expression of the Notch target genes HEY1, lunatic fringe (LFNG), and ephrin-B2, reduced phosphorylation of ERK1/2, and decreased expression of the angiogenic factor vascular endothelial growth factor (VEGF)-C. It inhibited the expression of genes enriched in tip cells, such as angiopoietin-2, ESM1, and Apelin, and impaired tip cell formation. SYNJ2BP inhibited endothelial cell migration, proliferation, and VEGF-induced angiogenesis. This could be rescued by blockade of Notch signaling or application of angiopoietin-2. SYNJ2BP-silenced human endothelial cells formed a functional vascular network in immunocompromised mice with significantly increased vascular density.

CONCLUSIONS

These data identify SYNJ2BP as a novel inhibitor of tip cell formation, executing its functions predominately by promoting Delta-Notch signaling.

Expression and significance of vascular endothelial growth factor A and C in leukemia central nervous system metastasis

Metastasis to the central nervous system (CNS) is an obstacle for leukemia treatment, the mechanisms of which remain to be elucidated. VEGF-A and VEGF-C are suspected to participate in this process. Paired of cerebrospinal fluid (CSF) and serum samples were collected from leukemia and control cases. Levels of VEGF-A and VEGF-C in both CSF (VEGF-ACSF, VEGF-CCSF) and serum (VEGF-ASerum, VEGF-CSerum) were detected by ELISA. Our data show that higher levels of VEGF-ACSF are closely related to CNS leukemia (CNSL), and VEGF-ACSF may be a better predictor than the other risk factors elucidating the pathogenesis and development of CNSL.

Tumor angiogenesis and anti-angiogenic therapy

Anti-angiogenic therapy is an anti-cancer strategy that targets the new vessels that grow to provide oxygen and nutrients to actively proliferating tumor cells. Most of the current anti-cancer reagents used in the clinical setting indiscriminately target all rapidly dividing cells, resulting in severe adverse effects such as immunosuppression, intestinal problems and hair loss. In comparison, anti-angiogenic reagents theoretically have fewer side effects because, except in the uterine endometrium, neoangiogenesis rarely occurs in healthy adults. Currently, the most established approach for limiting tumor angiogenesis is blockade of the vascular endothelial growth factor (VEGF) pathway. In line with the results of preclinical studies, significant therapeutic effects of VEGF blockers have been reported in various types of human cancers, even in patients with progressive/recurrent cancer who could not otherwise be treated. However, some patients are refractory to this treatment or acquire resistance to VEGF inhibitors. Moreover, several studies have shown that VEGF blockade damages healthy vessels and results in adverse effects such as hemorrhagic and thrombotic events. In recent research that indicated possible ways to overcome these problems, several VEGF-independent and tumor-selective pro-angiogenic mechanisms were discovered that could be targeted in combination with or without conventional VEGF blockade. These findings offer opportunities to greatly improve current anti-angiogenic treatment for cancer.

Angiogenesis: A Target in Solid Tumors, Also in Leukemia?

Targeting angiogenesis has become an established therapeutic approach to fighting solid tumor growth in cancer patients. Even though increased angiogenesis has long been recognized in various types of hematologic malignancies, the molecular basis underlying this angiogenic switch in leukemias remains poorly understood. The BM stroma is gaining increasing attention for its role in promoting leukemia growth and resistance against current treatments with tyrosine kinase inhibitors. This article provides a brief overview of the role of angiogenesis in leukemias, discusses recent insights into the role of placenta growth factor (PlGF), a VEGF family member, as a novel disease candidate in chronic myeloid leukemia (CML), and highlights the therapeutic potential of PlGF blockade for imatinib-resistant CML.

Small peptides derived from somatotropin domain-containing proteins inhibit blood and lymphatic endothelial cell proliferation, migration, adhesion and tube formation

Angiogenesis is thoroughly balanced and regulated in health; however, it is dysregulated in many diseases including cancer, age-related macular degeneration, cardiovascular diseases such as coronary and peripheral artery diseases and stroke, abnormal embryonic development, and abnormal wound healing. In addition to angiogenesis, lymphangiogenesis is pivotal for maintaining the immune system, homeostasis of body fluids and lymphoid organs; dysregulated lymphangiogenesis may cause inflammatory diseases and lymph node mediated tumor metastasis. Anti-angiogenic or anti-lymphangiogenic small peptides may play an important role as therapeutic agents normalizing angiogenesis or lymphangiogenesis in disease conditions. Several novel endogenous peptides derived from proteins containing a conserved somatotropin domain have been previously identified with the help of our bioinformatics-based methodology. These somatotropin peptides were screened for inhibition of angiogenesis and lymphangiogenesis using in vitro proliferation, migration, adhesion and tube formation assays with blood and lymphatic endothelial cells. We found that the peptides have the potential for inhibiting both angiogenesis and lymphangiogenesis. Focusing the study on the inhibition of lymphangiogenesis, we found that a peptide derived from the somatotropin conserved domain of transmembrane protein 45A human was the most potent lymphangiogenesis inhibitor, blocking lymphatic endothelial cell migration, adhesion, and tube formation.

Recent advances in anti-angiogenic therapy of cancer

Since angiogenesis is critical for tumor growth and metastasis, anti-angiogenic treatment is a highly promising therapeutic approach. Thus, for over last couple of decades, there has been a robust activity aimed towards the discovery of angiogenesis inhibitors. More than forty anti-angiogenic drugs are being tested in clinical trials all over the world. This review discusses agents that have approved by the FDA and are currently in use for treating patients either as single-agents or in combination with other chemotherapeutic agents.

Galectin-3C inhibits tumor growth and increases the anticancer activity of bortezomib in a murine model of human multiple myeloma

Galectin-3 is a human lectin involved in many cellular processes including differentiation, apoptosis, angiogenesis, neoplastic transformation, and metastasis. We evaluated galectin-3C, an N-terminally truncated form of galectin-3 that is thought to act as a dominant negative inhibitor, as a potential treatment for multiple myeloma (MM). Galectin-3 was expressed at varying levels by all 9 human MM cell lines tested. In vitro galectin-3C exhibited modest anti-proliferative effects on MM cells and inhibited chemotaxis and invasion of U266 MM cells induced by stromal cell-derived factor (SDF)-1α. Galectin-3C facilitated the anticancer activity of bortezomib, a proteasome inhibitor approved by the FDA for MM treatment. Galectin-3C and bortezomib also synergistically inhibited MM-induced angiogenesis activity in vitro. Delivery of galectin-3C intravenously via an osmotic pump in a subcutaneous U266 cell NOD/SCID mouse model of MM significantly inhibited tumor growth. The average tumor volume of bortezomib-treated animals was 19.6% and of galectin-3C treated animals was 13.5% of the average volume of the untreated controls at day 35. The maximal effect was obtained with the combination of galectin-3C with bortezomib that afforded a reduction of 94% in the mean tumor volume compared to the untreated controls at day 35. In conclusion, this is the first study to show that inhibition of galectin-3 is efficacious in a murine model of human MM. Our results demonstrated that galectin-3C alone was efficacious in a xenograft mouse model of human MM, and that it enhanced the anti-tumor activity of bortezomib in vitro and in vivo. These data provide the rationale for continued testing of galectin-3C towards initiation of clinical trials for treatment of MM.

Loss or inhibition of stromal-derived PlGF prolongs survival of mice with imatinib-resistant Bcr-Abl1(+) leukemia

Imatinib has revolutionized the treatment of Bcr-Abl1(+) chronic myeloid leukemia (CML), but, in most patients, some leukemia cells persist despite continued therapy, while others become resistant. Here, we report that PlGF levels are elevated in CML and that PlGF produced by bone marrow stromal cells (BMSCs) aggravates disease severity. CML cells foster a soil for their own growth by inducing BMSCs to upregulate PlGF, which not only stimulates BM angiogenesis, but also promotes CML proliferation and metabolism, in part independently of Bcr-Abl1 signaling. Anti-PlGF treatment prolongs survival of imatinib-sensitive and -resistant CML mice and adds to the anti-CML activity of imatinib. These results may warrant further investigation of the therapeutic potential of PlGF inhibition for (imatinib-resistant) CML.

A prospective clinical trial of lenalidomide with topotecan in women with advanced epithelial ovarian carcinoma

BACKGROUND

Lenalidomide is an anti-angiogenic IMiD(®) immunomodulatory drug. The objective of this study was to determine the maximum tolerated dose (MTD), overall safety profile, and activity of oral lenalidomide in combination with topotecan in women with advanced epithelial ovarian or primary peritoneal carcinoma.

METHODS

In this Phase I/II open-label, dose-escalation study, patients with histologically or cytologically confirmed advanced ovarian or primary peritoneal carcinoma with disease progression or recurrence following first-line therapy with a platinum agent and paclitaxel were eligible. The Phase I trial utilized a standard dose-escalation design to define the MTD and evaluate the safety profile of lenalidomide and topotecan. The starting doses were lenalidomide 5 mg, days 1-14, and intravenous topotecan 1.25 mg/m(2), days 1-5 of a 21-day cycle. Only the lenalidomide dose was escalated, in 5-mg increments up to 25 mg. Toxicity was graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events. The Phase II portion was designed to evaluate the antitumor activity based on objective response rate of lenalidomide and topotecan.

RESULTS

Five women with advanced epithelial ovarian carcinoma were enrolled, each receiving 5 mg oral lenalidomide and 1.25 mg/m(2) topotecan. Four patients discontinued because of dose-limiting toxicity, most commonly grade 4 neutropenia (n = 3). One patient discontinued because of lack of therapeutic effect. The study was terminated early for reasons of toxicity.

CONCLUSION

The addition of lenalidomide to topotecan is not a feasible drug combination in women with advanced epithelial ovarian carcinoma because of dose-limiting toxicity.

The bone marrow stroma in hematological neoplasms--a guilty bystander

In the setting of hematological neoplasms, changes in the bone marrow (BM) stroma might arise from pressure exerted by the neoplastic clone in shaping a supportive microenvironment, or from chronic perturbation of the BM homeostasis. Under such conditions, alterations in the composition of the BM stroma can be profound, and could emerge as relevant prognostic factors. In this Review, we delineate the multifaceted contribution of the BM stroma to the pathobiology of several hematological neoplasms, and discuss the impact of stromal modifications on the natural course of these diseases. Specifically, we highlight the involvement of BM stromal components in lymphoid and myeloid malignancies, and present the most relevant processes responsible for remodeling the BM stroma. The role of bystander BM stromal elements in the setting of hematological neoplasms is discussed, strengthening the rationale for treatment strategies that target the BM stroma.

A chemically modified antibody mediates complete eradication of tumours by selective disruption of tumour blood vessels

Background:

The possibility of eradicating cancer by selective destruction of tumour blood vessels may represent an attractive therapeutic avenue, but most pharmaceutical agents investigated so far did not achieve complete cures and are not completely specific. Antibody conjugates now allow us to evaluate the impact of selective vascular shutdown on tumour viability and to study mechanisms of action.

Methods:

We synthesised a novel porphyrin-based photosensitiser suitable for conjugation to antibodies and assessed anticancer properties of its conjugate with L19, a clinical-stage human monoclonal antibody specific to the alternatively spliced EDB domain of fibronectin, a marker of tumour angiogenesis.

Results:

Here we show in two mouse model of cancer (F9 and A431) that L19 is capable of highly selective in vivo localisation around tumour blood vessels and that its conjugate with a photosensitiser allows selective disruption of tumour vasculature upon irradiation, leading to complete and long-lasting cancer eradication. Furthermore, depletion experiments revealed that natural killer cells are essential for the induction of long-lasting complete responses.

Conclusions:

These results reinforce the concept that vascular shutdown can induce a curative avalanche of tumour cell death. Immuno-photodynamic therapy may be particularly indicated for squamous cell carcinoma of the skin, which we show to be strongly positive for markers of angiogenesis.

The microenvironment and molecular biology of the multiple myeloma tumor

Multiple myeloma (MM) is a deadly plasma cell cancer that resides in the bone marrow (BM). Numerous studies have demonstrated the involvement of the BM microenvironment supporting tumor growth, angiogenesis, bone disease and drug resistance. Reciprocal interactions between the different components of the BM microenvironment and the MM cells are necessary to regulate migration, differentiation, proliferation and survival of the malignant plasma cells. In this review we focus on the interactions and molecular mechanisms by which the BM microenvironment exert these effects. Better understanding of these interactions and the study of the epigenetic changes that tumor cells undergo are necessary in order to improve current treatments and for the discovery of new therapies that may eventually lead to a potential cure.

Synthesis and biological analysis of prostate-specific membrane antigen-targeted anticancer prodrugs

Ligand-targeted therapeutics have increased in prominence because of their potential for improved potency and reduced toxicity. However, with the advent of personalized medicine, a need for greater versatility in ligand-targeted drug design has emerged, where each tumor-targeting ligand should be capable of delivering a variety of therapeutic agents to the same tumor, each therapeutic agent being selected for its activity on a specific patient's cancer. In this report, we describe the use of a prostate-specific membrane antigen (PSMA)-targeting ligand to deliver multiple unrelated cytotoxic drugs to human prostate cancer (LNCaP) cells. We demonstrate that the PSMA-specific ligand, 2-[3-(1, 3-dicarboxy propyl)ureido] pentanedioic acid, is capable of mediating the targeted killing of LNCaP cells with many different therapeutic warheads. These results suggest that flexibility can be designed into ligand-targeted therapeutics, enabling adaptation of a single targeting ligand for the treatment of patients with different sensitivities to different chemotherapies.

Histone deacetylase inhibitors: potential targets responsible for their anti-cancer effect

The histone deacetylase inhibitors (HDACi) have demonstrated anticancer efficacy across a range of malignancies, most impressively in the hematological cancers. It is uncertain whether this clinical efficacy is attributable predominantly to their ability to induce apoptosis and differentiation in the cancer cell, or to their ability to prime the cell to other pro-death stimuli such as those from the immune system. HDACi-induced apoptosis occurs through altered expression of genes encoding proteins in both intrinsic and extrinsic apoptotic pathways; through effects on the proteasome/aggresome systems; through the production of reactive oxygen species, possibly by directly inducing DNA damage; and through alterations in the tumor microenvironment. In addition HDACi increase the immunogenicity of tumor cells and modulate cytokine signaling and potentially T-cell polarization in ways that may contribute the anti-cancer effect in vivo. Here, we provide an overview of current thinking on the mechanisms of HDACi activity, with attention given to the hematological malignancies as well as scientific observations arising from the clinical trials. We also focus on the immune effects of these agents.

Castleman's disease--a two compartment model of HHV8 infection

Castleman's disease is a primary infectious disease of the lymph node that causes local symptoms or a systemic inflammatory syndrome. Histopathology reveals a destroyed lymph node architecture that can range from hyaline-vascular disease to plasma-cell disease. Viral interleukin 6 (vIL-6) produced during the replication of human herpesvirus type 8 (HHV8) is the key driver of systemic inflammation and cellular proliferation. Stage progression of Castleman's disease results from switches between viral latency and lytic replication, and lymphatic and hematogenous spread. Multicentric plasma-cell disease in HIV-1 patients is associated with HHV8 infection. Polyclonal plasmablast proliferation escapes control in the germinal center with eventual malignant transformation into non-Hodgkin lymphoma. Surgery produces excellent results in unicentric disease, while multicentric disease responds to anti-CD20 therapy or IL-6 and chemotherapy. Lymphovascular endothelium and naive B cells are infectious reservoir-opening options for antiangiogenic and anti-CD19 strategies to enhance outcomes in patients with systemic disease.

The role of ets factors in tumor angiogenesis

Angiogenesis is a critical component of tumor growth. A number of growth factors, including VEGF, FGF, and HGF, have been implicated as angiogenic growth factors that promote tumor angiogenesis in different types of cancer. Ets-1 is the prototypic member of the Ets transcription factor family. Ets-1 is known to be a downstream mediator of angiogenic growth factors. Expression of Ets-1 in a variety of different tumors is associated with increased angiogenesis. A role for other selected members of the Ets transcription factor family has also been shown to be important for the development of tumor angiogenesis. Because Ets factors also express a number of other important genes involved in cell growth, they contribute not only to tumor growth, but to disease progression. Targeting Ets factors in mouse tumor models through the use of dominant-negative Ets proteins or membrane permeable peptides directed at competitively inhibiting the DNA binding domain has now demonstrated the therapeutic potential of inhibiting selected Ets transcription factors to limit tumor growth and disease progression.

Major Tumor Shrinking and Persistent Molecular Remissions After Consolidation With Bortezomib, Thalidomide, and Dexamethasone in Patients With Autografted Myeloma

Purpose

We investigated the effect on minimal residual disease, by qualitative and real-time quantitative polymerase chain reaction (RQ-PCR), of a consolidation regimen that included bortezomib, thalidomide, and dexamethasone (VTD) in patients with multiple myeloma (MM) responding to autologous stem-cell transplantation (auto-SCT).

Patients and Methods

Patients achieving at least very good partial response who had an available molecular marker based on the immunoglobulin heavy-chain rearrangement received four courses of treatment every month: four infusions per month of bortezomib at 1.6 mg/m2, thalidomide at 200 mg/d, and dexamethasone at 20 mg/d on days 1 to 4, 8 to 11, and 15 to 18. Patients were studied with tumor-clone–specific primers by qualitative nested PCR and RQ-PCR.

Results

Of 39 patients enrolled, 31 received the four VTD courses. Immunofixation complete responses increased from 15% after auto-SCT to 49% after VTD. Molecular remissions (MRs) were 3% after auto-SCT and 18% after VTD. Median time to maximum response was 3.5 months. So far, no patient in MR has relapsed (median follow-up, 42 months). VTD consolidation induced an additional depletion of 4.14 natural logarithms of tumor burden by RQ-PCR. Patients with a tumor load less than the median value after VTD had outcomes better than those who had tumor loads above the median value after VTD (at median follow-up: progression-free survival, 100% v 57%; P < .001).

Conclusion

To the best of our knowledge, this study is the first to document the occurrence of persistent MRs in a proportion of MM patients treated without allogeneic transplantation. Moreover, the major reduction in tumor load recorded by RQ-PCR after VTD suggests that unprecedented levels of tumor cell reduction can be achieved in MM thanks to the new nonchemotherapeutic drugs.

Shedding of the endothelial receptor tyrosine kinase Tie2 correlates with leukemic blast burden and outcome after allogeneic hematopoietic stem cell transplantation for AML

Angiogenesis plays an important role in the growth and viability of hematologic malignancies. Emerging data suggest a crucial involvement of the endothelial-specific Tie2 receptor and its antagonistic ligand Angiopoietin-2 (Ang-2) in this process. The purpose of this study was to elucidate whether the soluble domain of the Tie2 receptor (sTie2)predicts outcome in patients with acute myeloid leukemia(AML) undergoing allogeneic hematopoietic stem cell transplantation(HSCT). Serum levels of sTie2 and Ang-2 were measured by ELISA in 181 AML patients before conditioning for HSCT. The median follow-up time was 22 months after HSCT. Pre-HSCT sTie2 levels were significantly higher inpatients (median 2.2 (range 1.8-3.0) ng/mL) compared to healthy controls (1.3 (0.9-1.6); p<0.0001). Elevated sTie2 levels were independently associated with active AML but did not relate to cytogenetics/mutational status before transplantation. Logistic regression analysis identified elevated sTie2 (odds ratio (OR) 3.07 (95% confidence interval(CI; 1.56-6.04), p=0.001) as a strong predictor for disease relapse and poor overall survival after HSCT. In a multimarker approach the highest risk for relapse was observed inpatients with both elevated sTie2 and elevated Ang-2 (OR 4.07, (95% CI 1.79-9.25) p<0.0001), as well as patients with both elevated Ang-2 and elevated bone marrow blast count (OR 4.16, (95% CI 1.88-7.36) p<0.0001). Elevated serum sTie2 levels were related to active leukemia,correlated with the percentage of leukemic blasts in the bone marrow, and independently predicted relapse in AML patients after allogeneic HSCT. Furthermore, our data indicate that Tie2 shedding and Ang-2 release seem to reflect overlapping, but nevertheless distinctive features in leukemia-associated neoangiogenesis.

Anticancer Role of PPARgamma Agonists in Hematological Malignancies Found in the Vasculature, Marrow, and Eyes

The use of targeted cancer therapies in combination with conventional chemotherapeutic agents and/or radiation treatment has increased overall survival of cancer patients. However, longer survival is accompanied by increased incidence of comorbidities due, in part, to drug side effects and toxicities. It is well accepted that inflammation and tumorigenesis are linked. Because peroxisome proliferator-activated receptor (PPAR)-gamma agonists are potent mediators of anti-inflammatory responses, it was a logical extension to examine the role of PPARgamma agonists in the treatment and prevention of cancer. This paper has two objectives: first to highlight the potential uses for PPARgamma agonists in anticancer therapy with special emphasis on their role when used as adjuvant or combined therapy in the treatment of hematological malignancies found in the vasculature, marrow, and eyes, and second, to review the potential role PPARgamma and/or its ligands may have in modulating cancer-associated angiogenesis and tumor-stromal microenvironment crosstalk in bone marrow.

Contribution of bone microenvironment to leukemogenesis and leukemia progression

Tumor microenvironment has a major role in cancer progression and resistance to treatment. The bone marrow (BM) is a dynamic network of growth factors, cytokines and stromal cells, providing a permissive environment for leukemogenesis and progression. Both BM stroma and leukemic blasts promote angiogenesis, which is increased in acute lymphoblastic leukemia and acute myeloid leukemia. Growth factors like vascular endothelial growth factor (VEGF), basic fibroblast growth factor and angiopoietins are the main proangiogenic mediators in acute leukemia. Autocrine proleukemic loops have been described for VEGF and angiopoietin in hematopoietic cells. Interactions of stromal cells and extracellular matrix with leukemic blasts can also generate antiapoptotic signals that contribute to neoplastic progression and persistence of treatment-resistant minimal residual disease. High expression of CXC chemokine ligand 4 (CXCR4) by leukemic blasts and activation of the CXCR4-CXCL12 axis is involved in leukemia progression and disruption of normal hematopoiesis. Leukemia-associated bone microenvironment markers could be used as prognostic or predictive indicators of disease progression and/or treatment outcome. Studies related to bone microenvironment would likely provide a better understanding of the treatment resistance associated with leukemia therapy and design of new treatments.

Suppression of lung cancer in murine model: treated by combination of recombinant human endostsatin adenovirus with low-dose cisplatin

BACKGROUND

The sustained growth of tumors necessitates neovascularization. As one of the potent endogenous vascular inhibitors, endostatin has been widely used in antiangiogenesis therapy for tumor. Cisplatin is normally administered in chemotherapy for lung cancer but accompanied with serious side effects. In the current study, we investigated a novel chemo-antiangiogenesis therapeutic strategy to both improve toxic effects on lung cancer cells and reduce damages to normal cells in the anti-tumor therapy.

METHODS

In vitro, we transduced LLC cells with Ad-hEndo and collected supernatants. Western blotting analysis of the supernatants revealed expression of endostatin. In vivo, to fully investigate the suppression effect on murine lung cancer of the combination therapy, we injected recombinant human endostatin adenovirus intratumorally plus a low dose of cisplatin intraperitoneally routinely. The tumor volume and survival time were observed. Angiogenesis was apparently inhibited within the tumor tissues and on the alginate beads. Assessment of apoptotic cells by the TUNEL assay was conducted in the tumor tissues.

RESULTS

The combination treatment significantly suppressed the tumor growth and prolonged survival time of the murine LLC tumor model. This anti-tumor activity was associated with decreased microvessel density and increased apoptotic index of tumor cells.

CONCLUSION

According to the results in this study, recombinant human endostatin adenovirus in combination with a low dose of cisplatin demonstrated apparent synergistic anti-tumor activity without marked toxicity. Thus, these observations may provide a rational alternative for lung cancer treatment.