Differential expression of decorin by human malignant and benign vascular tumors.

An increasing amount of evidence indicates that a small extracellular chondroitin/dermatan sulfate proteoglycan, decorin, is indirectly involved in angiogenesis. Given that angiogenesis is a sine qua non for tumor growth and progression, we attempted to examine whether human malignant vascular tumors differ from human benign vascular tumors in terms of their decorin expression and synthesis. CD31 immunostaining demonstrated that the human malignant vascular tumors Kaposi's sarcoma and angiosarcoma were filled with capillary-like structures, whereas in benign cavernous and capillary hemangiomas, blood vessels were not as abundantly present. By utilizing in situ hybridization and immunocytochemical assays for decorin, we showed that there was no detectable decorin mRNA expression or immunoreactivity within the tumor mass in the Kaposi's sarcoma or angiosarcoma group. Instead, decorin was expressed in the connective tissue stroma lining the sarcoma tissue. In contrast to sarcomas, in hemangiomas, decorin mRNA expression and immunoreactivity were observed also within the tumor mass, particularly in the connective tissue stroma surrounding the clusters of intratumoral blood vessels. Finally, distribution of type I collagen was found to be similar to that of decorin in these tumor tissues. Our findings can be explained with different states of angiogenesis in dissimilar growths. In sarcomas, angiogenesis is extremely powerful, whereas in hemangiomas, angiogenesis has ceased. Thus, decorin is likely to possess a suppressive effect on human tumor angiogenesis in vivo, as previously described by studies using different experimental models. Decorin certainly provides a usable biomarker for distinguishing between benign and malignant vascular tumors in patients.     

Targeting of Beta Adrenergic Receptors Results in Therapeutic Efficacy against Models of Hemangioendothelioma and Angiosarcoma

Therapeutic targeting of the beta-adrenergic receptors has recently shown remarkable efficacy in the treatment of benign vascular tumors such as infantile hemangiomas. As infantile hemangiomas are reported to express high levels of beta adrenergic receptors, we examined the expression of these receptors on more aggressive vascular tumors such as hemangioendotheliomas and angiosarcomas, revealing beta 1, 2, and 3 receptors were indeed present and therefore aggressive vascular tumors may similarly show increased susceptibility to the inhibitory effects of beta blockade. Using a panel of hemangioendothelioma and angiosarcoma cell lines, we demonstrate that beta adrenergic inhibition blocks cell proliferation and induces apoptosis in a dose dependent manner. Beta blockade is selective for vascular tumor cells over normal endothelial cells and synergistically effective when combined with standard chemotherapeutic or cytotoxic agents. We demonstrate that inhibition of beta adrenergic signaling induces large scale changes in the global gene expression patterns of vascular tumors, including alterations in the expression of established cell cycle and apoptotic regulators. Using in vivo tumor models we demonstrate that beta blockade shows remarkable efficacy as a single agent in reducing the growth of angiosarcoma tumors. In summary, these experiments demonstrate the selective cytotoxicity and tumor suppressive ability of beta adrenergic inhibition on malignant vascular tumors and have laid the groundwork for a promising treatment of angiosarcomas in humans.     

Insulin-like growth factor binding proteins and angiogenesis: from cancer to cardiovascular disease

Angiogenesis is a tightly regulated activity that is vital during embryonic development and for normal physiological repair processes and reproduction in healthy adults. Pathological angiogenesis is a driving force behind a variety of diseases including cancer and retinopathies, and inhibition of angiogenesis is a therapeutic option that has been the subject of much research, with several inhibitory agents now available for medical therapy. Conversely, therapeutic angiogenesis has been mooted as having significant potential in the treatment of ischemic conditions such as angina pectoris and peripheral arterial disease, but so far there has been less translation from lab to bedside.The insulin-like growth factor binding proteins (IGFBP) are a family of seven proteins essential for the binding and transport of the insulin-like growth factors (IGF). It is being increasingly recognised that IGFBPs have a significant role beyond simply modulating IGF activity, with evidence of both IGF dependent and independent actions through a variety of mechanisms. Moreover, the action of the IGFBPs can be stimulatory or inhibitory depending on the cell type and environment. Specifically the IGFBPs have been heavily implicated in angiogenesis, both pathological and physiological, and they have significant promise as targeted cell therapy agents for both pathological angiogenesis inhibition and therapeutic angiogenesis following ischemic injury. In this short review we will explore the current understanding of the individual impact of each IGFBP on angiogenesis, and the pathways through which these effects occur.     

Identifying potential regulators of infantile hemangioma progression through large-scale expression analysis: a possible role for the immune system and indoleamine 2,3 dioxygenase (IDO) during involution

Hemangiomas are benign endothelial tumors. Often referred to as hemangiomas of infancy (HOI), these tumors are the most common tumor of infancy. Most of these lesions proliferate rapidly in the first months of life, and subsequently slowly involute during early childhood without significant complications. However, they often develop on the head or neck, and may pose a significant cosmetic concern for families. In addition, a fraction of these tumors can grow explosively and ulcerate, bleed, or obstruct vision or airway structures. Current treatments for these tumors are associated with significant side effects, and our knowledge of the biology of hemangiomas is limited. The natural evolution of these lesions creates a unique opportunity to study the changes in gene expression that occur as the endothelium of these tumors proliferates and then subsequently regresses. Such information may also increase our understanding of the basic principals of angiogenesis in normal and abnormal tissue. We have performed large-scale genomic analysis of hemangioma gene expression using DNA microarrays. We recently identified insulin-like growth factor 2 as a potentially important regulator of hemangioma growth using this approach. However, little is known about the mechanisms involved in hemangioma involution. Here we explore the idea that hemangioma involution might be an immune-mediated process and present data to support this concept. We also demonstrate that proliferating hemangiomas express indoleamine 2,3 dioxygenase (IDO) and discuss a possible mechanism that accounts for the often slow regression of these lesions.     

Pathogenic angiogenesis in IBD and experimental colitis: new ideas and therapeutic avenues

Angiogenesis is now understood to play a major role in the pathology of chronic inflammatory diseases and is indicated to exacerbate disease pathology. Recent evidence shows that angiogenesis is crucial during inflammatory bowel disease (IBD) and in experimental models of colitis. Examination of the relationship between angiogenesis and inflammation in experimental colitis shows that initiating factors for these responses simultaneously increase as disease progresses and correlate in magnitude. Recent studies show that inhibition of the inflammatory response attenuates angiogenesis to a similar degree and, importantly, that inhibition of angiogenesis does the same to inflammation. Recent data provide evidence that differential regulation of the angiogenic mediators involved in IBD-associated chronic inflammation is the root of this pathological angiogenesis. Many factors are involved in this phenomenon, including growth factors/cytokines, chemokines, adhesion molecules, integrins, matrix-associated molecules, and signaling targets. These factors are produced by various vascular, inflammatory, and immune cell types that are involved in IBD pathology. Moreover, recent studies provide evidence that antiangiogenic therapy is a novel and effective approach for IBD treatment. Here we review the role of pathological angiogenesis during IBD and experimental colitis and discuss the therapeutic avenues this recent knowledge has revealed.     

Metformin's antitumour and anti‐angiogenic activities are mediated by skewing macrophage polarization

Beneficial effects of metformin on cancer risk and mortality have been proved by epidemiological and clinical studies, thus attracting research interest in elucidating the underlying mechanisms. Recently, tumour‐associated macrophages (TAMs) appeared to be implicated in metformin‐induced antitumour activities. However, how metformin inhibits TAMs‐induced tumour progression remains ill‐defined. Here, we report that metformin‐induced antitumour and anti‐angiogenic activities were not or only partially contributed by its direct inhibition of functions of tumour and endothelial cells. By skewing TAM polarization from M2‐ to M1‐like phenotype, metformin inhibited both tumour growth and angiogenesis. Depletion of TAMs by clodronate liposomes eliminated M2‐TAMs‐induced angiogenic promotion, while also abrogating M1‐TAMs‐mediated anti‐angiogenesis, thus promoting angiogenesis in tumours from metformin treatment mice. Further in vitro experiments using TAMs‐conditioned medium and a coculture system were performed, which demonstrated an inhibitory effect of metformin on endothelial sprouting and tumour cell proliferation promoted by M2‐polarized RAW264.7 macrophages. Based on these results, metformin‐induced inhibition of tumour growth and angiogenesis is greatly contributed by skewing of TAMs polarization in microenvironment, thus offering therapeutic opportunities for metformin in cancer treatment.     

A possible mechanism of spontaneous involution of infantile hemangioma

Infantile hemangiomas are common vascular tumours which exhibit a rapid proliferating phase followed by spontaneously involuting for a long time. The formation and development mechanisms are not clear yet. Recent studies show that hemangioma-derived stem cells have multipotential differentiation abilities, including endothelial and mesenchymal differentiation. In addition, mesenchymal stem cell has the capability of inducing endothelial cell apoptosis, differentiating into adipocytes and triggering the involution of hemangiomas. Thus we hypothesize that mesenchymal stem cell may be the source of spontaneously regression of hemangiomas. Further investigations may be needed to develop potential therapeutic implications of mesenchymal stem cell in treating hemangiomas.     

Therapeutic coagulation induced in cavernous hemangioma by use of percutaneous copper needles.

Fifty-two patients with cavernous hemangiomas were therapeutically coagulated by use of percutaneous copper needles. Of the 52 patients, 32 had cavernous hemangiomas of the face and neck and 20 had cavernous hemangiomas of the trunk and extremities. All have gained effective treatment. Through in vitro tests, animal experiments, and clinical studies, I have confirmed that copper needles produce coagulation and destruction of cavernous hemangiomas. The mechanism, indications, technique, prevention and treatment of complications, and an analysis of copper concentrations in the patients' blood are discussed. My conclusion is that this is a simple, safe, and effective treatment for cavernous hemangiomas.     

Effects of betamethasone,sulindac and quinacrine drugs on the inflammatory neoangiogenesis response induced by polyurethane sponge implanted in mouse

In this study, we showed the effect of the betamethasone, sulindac and quinacrine alone or combined, on the inflammatory angiogenesis promoted by polyurethane sponge on mice. The main finding reported here is that the formation of new blood vessels was strongly inhibited by low concentration of betamethasone, sulindac or quinacrine, whether alone or in combination. It is known that steroidal anti-inflammatory drugs inhibit the enzymes required for the production of prostaglandins through a nuclear glucocorticoid receptor (GR) mediated mechanism. This mechanism may occur in endothelial cells as well. Considering that activity of cyclo-oxigenases 1 and 2 is inhibited by sulindac, and that these enzymes are located in the stromal tissue, we propose that the anti-angiogenic effect of these agents may occur via inhibition of both COX isoforms. On the other hand, quinacrine inhibited PLA2 activity, and we propose here that the anti-angiogenic effect occurs via inhibition of the enzyme PLA2. The potentiated effect of the association of betamethasone, sulindac and quinacrine may have some therapeutic benefit in the control of pathological angiogenesis. Further studies are required to validate these propositions.     

The role of multipotential stem cells in human infantile hemangioma

Hemangioma is the most common benign vascular tumor in infants and children with unknown etiology and pathogenesis. It is characterized by rapid proliferation followed by a slow involution phase. Histological analyses of infantile hemangioma (IH) in the early proliferating phase have generated a number of developmental theories suggesting an embryonic or primitive cell origin. We here hypothesize the IH may originate from multipotential stem cells. Further investigations of these hemangioma-initiating cells may improve our understanding of their function and possibly lead to novel therapeutic modalities for hemangiomas.     

Application of adipose-derived stem cells in treating fibrosis

Fibrosis is the hyperactivation of fibroblasts that results in excessive accumulation of extracellular matrix, which is involved in numerous pathological changes and diseases. Adipose-derived stem cells (ASCs) are promising seed cells for regenerative medicine due to their bountiful source, low immunogenicity and lack of ethical issues. Their anti-fibrosis, immunomodulation, angiogenesis and other therapeutic effects have made them suitable for treating fibrosis-related diseases. Here, we review the literature on ASCs treating fibrosis, elaborate and discuss their mechanisms of action, changes in disease environment, ways to enhance therapeutic effects, as well as current preclinical and clinical studies, in order to provide a general picture of ASCs treating fibrotic diseases.     

Molecular pathogenesis of vascular anomalies: classification into three categories based upon clinical and biochemical characteristics

Vascular tumors and malformations can be challenging to diagnose. Although they can resemble one another, their classification into tumors, such as hemangiomas of infancy, and malformations, such as venous or arteriovenous malformations, is based not only on their divergent biological behavior, but also on their pathogenesis. This review examines the molecular pathobiology of the processes involved in the development of these vascular birthmarks as they are currently understood. The terms hemangioma, hemangiosarcoma, and vascular proliferation are often used interchangeably, even though these entities are clinically and biochemically distinct. A more precise classification is necessary to facilitate communication between basic scientists and clinicians. Vasculogenesis, the in situ differentiation of blood vessels, occurs very early in the developing embryo. In vivo and in vitro studies, as well as knockout models, seem to indicate that this mechanism is unlikely to be involved in the development of either vascular malformations or hemangiomas of infancy. Recent advances in embryonic angiogenesis, especially explorations of mechanisms of vascular remodeling, have brought new understanding of the pathogenesis of vascular malformations. Vascular remodeling, an integral part of angiogenesis that centers upon the interactions between pericytes and endothelial cells, has been shown to be defective in certain experimental models and in some familial cases of vascular malformation. The occurrences of arteriovenous malformations in territories susceptible to increased remodeling also point towards epigenetic events in the development of vascular malformations.     

Cathepsin L,target in cancer treatment?

Cathepsin L, a cysteine protease, is considered to be a potential therapeutic target in cancer treatment. Proteases are involved in the development and progression of cancer. Inhibition of activity of specific proteases may slow down cancer progression. In this review, we evaluate recent studies on the inhibition of cathepsin L in cancer. The effects of cathepsin L inhibition as a monotherapy on apoptosis and angiogenesis in cancer are ambiguous. Cathepsin L inhibition seems to reduce invasion and metastasis, but there is concern that selective cathepsin L inhibition induces compensatory activity by other cathepsins. The combination of cathepsin L inhibition with conventional chemotherapy seems to be more promising and has yielded more consistent results. Future research should be focused on the mechanisms and effects of this combination therapy.     

Saikosaponin C induces endothelial cells growth, migration and capillary tube formation

Saikosaponin C is one of the saikosaponins that are consisted in a Chinese herb, Radix Bupleuri. Recently, saikosaponins have been reported to have properties of cell growth inhibition, inducing cancer cells differentiation and apoptosis. However, saikosaponin C had no correlation with cell growth inhibition. In this study, we investigated the role of saikosaponin C on the growth of endothelial cells and angiogenesis. We found that saikosaponin C yielded a potent effect on inducing human umbilical vein endothelial cells (HUVECs) viability and growth. In addition to inducing endothelial cells growth, saikosaponin C also induced endothelial cells migration and capillary tube formation. The gene expression or activation of matrix metalloproteinase-2 (MMP-2), vascular endothelial growth factor (VEGF) and the p42/p44 mitogen-activated protein kinase (MAPK, ERK) that correlated with endothelial cells growth, migration and angiogenesis were also induced by saikosaponin C. From these results, we suggest that saikosaponin C may have the potential for therapeutic angiogenesis but is not suitable for cancer therapy.     

Antiangiogenic mechanisms of diet-derived polyphenols

Accumulating evidence demonstrates that polyphenols in natural products are beneficial against human lethal diseases such as cancer and metastasis. The underlying mechanisms of anti-cancer effects are complex. Recent studies show that several polyphenols, including epigallocatechin-3-gallate (EGCG) in green tea and resveratrol in red wine, inhibit angiogenesis when administrated orally. These polyphenols have direct effects on suppression of angiogenesis in several standard animal angiogenesis models. Because angiogenesis is involved in many diseases such as cancer, diabetic retinopathy and chronic inflammations, the discovery of these polyphenols as angiogenesis inhibitors has shed light on the health beneficial mechanisms of natural products, which are rich in these molecules. At the molecular level, recent studies have provided important information on how these molecules inhibit endothelial cell growth. Perhaps the greatest therapeutic advantage of these small natural molecules over large protein compounds is that they can be administrated orally without causing severe side effects. It is anticipated that more polyphenols in natural products will be discovered as angiogenesis inhibitors and that these natural polyphenols could serve as leading structures in the discovery of more potent, synthetic angiogenesis inhibitors.     

Autophagy triggered by magnolol derivative negatively regulates angiogenesis

Angiogenesis has a key role in the tumor progression and metastasis; targeting endothelial cell proliferation has emerged as a promising therapeutic strategy for the prevention of cancer. Previous studies have revealed a complex association between the process of angiogenesis and autophagy and its outcome on tumorigenesis. Autophagy, also known as type-II cell death, has been identified as an alternative way of cell killing in apoptotic-resistant cancer cells. However, its involvement in chemoresistance and tumor promotion is also well known. In this study, we used a derivate of natural product magnolol (Ery5), a potent autophagy inducer, to study the association between the autophagy and angiogenesis in both in vitro and in vivo model system. We found that the robust autophagy triggered by Ery5, inhibited angiogenesis and caused cell death independent of the apoptosis in human umbilical cord vein endothelial cells and PC-3 cells. Ery5 induced autophagy effectively inhibited cell proliferation, migration, invasion and tube formation. We further demonstrated that Ery5-mediated autophagy and subsequent inhibition of angiogenesis was reversed when autophagy was inhibited through 3-methyl adenine and knocking down of key autophagy proteins ATG7 and microtubule-associated protein light chain 3. While evaluating the negative regulation of autophagy on angiogenesis, it was interesting to find that angiogenic environment produced by the treatment of VEGF and CoCl2 remarkably downregulated the autophagy and autophagic cell death induced by Ery5. These studies, while disclosing the vital role of autophagy in the regulation of angiogenesis, also suggest that the potent modulators of autophagy can lead to the development of effective therapeutics in apoptosis-resistant cancer.     

CDK4/6 inhibition antagonizes the cytotoxic response to anthracycline therapy

Triple-negative breast cancer (TNBC) is an aggressive disease that lacks established markers to direct therapeutic intervention. Thus, these tumors are routinely treated with cytotoxic chemotherapies (e.g., anthracyclines), which can cause severe side effects that impact quality of life. Recent studies indicate that the retinoblastoma tumor suppressor (RB) pathway is an important determinant in TNBC disease progression and therapeutic outcome. Furthermore, new therapeutic agents have been developed that specifically target the RB pathway, potentially positioning RB as a novel molecular marker for directing treatment. The current study evaluates the efficacy of pharmacological CDK4/6 inhibition in combination with the widely used genotoxic agent doxorubicin in the treatment of TNBC. Results demonstrate that in RB-proficient TNBC models, pharmacological CDK4/6 inhibition yields a cooperative cytostatic effect with doxorubicin but ultimately protects RB-proficient cells from doxorubicin-mediated cytotoxicity. In contrast, CDK4/6 inhibition does not alter the therapeutic response of RB-deficient TNBC cells to doxorubicin-mediated cytotoxicity, indicating that the effects of doxorubicin are indeed dependent on RB-mediated cell cycle control. Finally, the ability of CDK4/6 inhibition to protect TNBC cells from doxorubicin-mediated cytotoxicity resulted in recurrent populations of cells specifically in RB-proficient cell models, indicating that CDK4/6 inhibition can preserve cell viability in the presence of genotoxic agents. Combined, these studies suggest that while targeting the RB pathway represents a novel means of treatment in aggressive diseases such as TNBC, there should be a certain degree of caution when considering combination regimens of CDK4/6 inhibitors with genotoxic compounds that rely heavily on cell proliferation for their cytotoxic effects.     

Toxicity and anti-angiogenicity evaluation of Pak1 inhibitor IPA-3 using zebrafish embryo model

p21-activated kinase 1 (Pak1)—a key node protein kinase regulating various cellular process including angiogenesis—has been recognised to be a therapeutic target for multitude of diseases, and hence, various small molecule inhibitors targeting its activity have been tested. However, the direct toxic and anti-angiogenic effects of these pharmacologic agents have not been examined. In this study, we evaluate the translational efficacy of Pak1 inhibitor IPA-3 using zebrafish toxicity model system to stratify its anti-angiogenic potential and off-target effects to streamline the compound for further therapeutic usage. The morphometric analysis has shown explicit delay in hatching, tail bending, pericardial sac oedema and abnormal angiogenesis. We provide novel evidence that Pak1 inhibitor could act as anti-angiogenic agents by impeding the development of sub-intestinal vessel (SIV) and intersegmental vessels (ISVs) by suppressing the expression of vascular endothelial growth factor (VEGF), VEGF receptor 2 (VEGFR2), neurophilin 1 (NRP1) and its downstream genes matrix metalloproteinase (MMP)-2 and MMP-9. Knockdown studies using 2-O-methylated oligoribonucleotides targeting Pak1 also revealed similar phenotypes with inhibition of angiogenesis accompanied with deregulation of major angiogenic factor and cardiac-specific genes. Taken together, our findings indicate that Pak1 signalling facilitates enhanced angiogenesis and also advocated the design and use of small molecule inhibitors of Pak1 as potent anti-angiogenic agents and suggest their utility in combinatorial therapeutic approaches targeting anomalous angiogenesis.     

Comparative study of human steroid 5alpha-reductase isoforms in prostate and female breast skin tissues: sensitivity to inhibition by finasteride and epristeride

Steroid 5alpha-reductase (5-AR) catalyses the reduction of testosterone (T) to dihydrotestosterone (DHT). The 5alpha-reductase found in human benign prostatic hyperplasia (BPH) has been compared with that found in human breast skin tissue in respect of sensitivity to inhibition by Finasteride and Epristeride. Kinetic studies showed the presence of two isoforms of 5alpha-reductase in benign prostatic hyperplasia indicated by low and high Km isoforms for testosterone, while female breast skin tissue contained only one isoform. The isoforms differ in their affinity for the inhibitors Finasteride and Epristeride, both compounds being more effective for the low Km 5alpha-reductase isoform than the high Km 5alpha-reductase of prostatic tissue, with Finasteride displaying competitive inhibition and Epristeride uncompetitive. Finasteride and Epristeride are also inhibitors of skin 5alpha-reductase, which possesses a comparable Ki for Finasteride to that of the low Km prostatic enzyme, but Epristeride was a less potent inhibitor of the skin enzyme relative to the prostate isoform. These results suggest that the inhibitors have therapeutic potential, other than for treatment of benign prostatic hyperplasia, for treating skin disorders influenced by the action of dihydrotestosterone and warrant further investigation.     

CDK4/6 inhibition antagonizes the cytotoxic response to anthracycline therapy

Triple-negative breast cancer (TNBC) is an aggressive disease that lacks established markers to direct therapeutic intervention. Thus, these tumors are routinely treated with cytotoxic chemotherapies (e.g., anthracyclines), which can cause severe side effects that impact quality of life. Recent studies indicate that the retinoblastoma tumor suppressor (RB) pathway is an important determinant in TNBC disease progression and therapeutic outcome. Furthermore, new therapeutic agents have been developed that specifically target the RB pathway, potentially positioning RB as a novel molecular marker for directing treatment. The current study evaluates the efficacy of pharmacological CDK4/6 inhibition in combination with the widely used genotoxic agent doxorubicin in the treatment of TNBC. Results demonstrate that in RB-proficient TNBC models, pharmacological CDK4/6 inhibition yields a cooperative cytostatic effect with doxorubicin but ultimately protects RB-proficient cells from doxorubicin-mediated cytotoxicity. In contrast, CDK4/6 inhibition does not alter the therapeutic response of RB-deficient TNBC cells to doxorubicin-mediated cytotoxicity, indicating that the effects of doxorubicin are indeed dependent on RB-mediated cell cycle control. Finally, the ability of CDK4/6 inhibition to protect TNBC cells from doxorubicin-mediated cytotoxicity resulted in recurrent populations of cells specifically in RB-proficient cell models, indicating that CDK4/6 inhibition can preserve cell viability in the presence of genotoxic agents. Combined, these studies suggest that while targeting the RB pathway represents a novel means of treatment in aggressive diseases such as TNBC, there should be a certain degree of caution when considering combination regimens of CDK4/6 inhibitors with genotoxic compounds that rely heavily on cell proliferation for their cytotoxic effects.