Jujuboside B suppresses angiogenesis and tumor growth via blocking VEGFR2 signaling pathway.

Jujuboside B (JuB), one of the main active triterpenoid saponins from the traditional Chinese medicine Ziziphus jujuba, possesses a wide range of pharmacological activities. However, it is unknown whether JuB can inhibit tumor angiogenesis, a crucial step in solid tumor growth. In this study, we found that JuB significantly inhibited the proliferation, migration, and tube formation of human umbilical vein endothelial cells in a dose-dependent manner. JuB also suppressed angiogenesis in chick embryo chorioallantoic membranes and Matrigel plugs. Moreover, through angiogenesis inhibition, JuB delayed the growth of human HCT-15 colorectal cancer xenograft in mice. Western blot assay demonstrated that JuB inhibited the phosphorylation of VEGFR2 and its key downstream protein kinases, such as Akt, FAK, Src, and PLCγ1. In conclusion, the antiangiogenic potency and molecular mechanism of JuB are revealed for the first time, indicating that this triterpene saponin may be further explored as a potential drug candidate or lead compound for antiangiogenic cancer therapy.

New lead compounds identification against KRas mediated cancers through pharmacophore-based virtual screening and in vitro assays.

Cancer remains the leading cause of mortality and morbidity in the world, with 19.3 million new diagnoses and 10.1 million deaths in 2020. Cancer is caused due to mutations in proto-oncogenes and tumor-suppressor genes. Genetic analyses found that Ras (Rat sarcoma) is one of the most deregulated oncogenes in human cancers. The Ras oncogene family members including NRas (Neuroblastoma ras viral oncogene homolog), HRas (Harvey rat sarcoma) and KRas are involved in different types of human cancers. The mutant KRas is considered as the most frequent oncogene implicated in the development of lung, pancreatic and colon cancers. However, there is no efficient clinical drug even though it has been identified as an oncogene for 30 years. Therefore there is an emerging need to develop potent, new anticancer drugs. In this study, computer-aided drug designing approaches as well as experimental methods were employed to find new and potential anti-cancer drugs. The pharmacophore model was developed from an already known FDA approved anti-cancer drug Bortezomib using the software MOE. The validated pharmacophore model was then used to screen the in-house and commercially available databases. The pharmacophore-based virtual screening resulted in 26 and 86 hits from in-house and commercial databases respectively. Finally, 6/13 (in-house database) and 24/64 hits (commercial databases) were selected with different scaffolds having good interactions with the significant active residues of KRasG12D protein that were predicted as potent lead compounds. Finally, the results of pharmacophore-based virtual screening were further validated by molecular dynamics simulation analysis. The 6 hits of the in-house database were further evaluated experimentally. The experimental results showed that these compounds have good anti-cancer activity which validate the protocol of our in silico studies. KRasG12D protein is a very important anti-cancer target and potent inhibitors for this target are still not available, so small lead compound inhibitors were identified to inhibit the activity of this protein by blocking the GTP-binding pocket.Communicated by Ramaswamy H. Sarma.

Hyaluronic Acid with Bone Substitutes Enhance Angiogenesis In Vivo.

Introduction: The effective induction of angiogenesis is directly related to the success of bone-substitute materials (BSM) for maxillofacial osseous regeneration. Therefore, the addition of pro-angiogenic properties to a commercially available bovine bone-substitute material in combination with hyaluronic acid (BSM+) was compared to the same bone-substitute material without hyaluronic acid (BSM) in an in-vivo model. Materials and Methods: BSM+ and BSM were incubated for six days on the chorioallantoic membrane (CAM) of fertilized chicken eggs. Microscopically, the number of vessels and branching points, the vessel area and vessel length were evaluated. Subsequently, the total vessel area and brightness integration were assessed after immunohistochemical staining (H&E, alphaSMA). Results: In the BSM+ group, a significantly higher number of vessels (p < 0.001), branching points (p = 0.001), total vessel area (p < 0.001) as well as vessel length (p = 0.001) were found in comparison to the BSM group without hyaluronic acid. Immunohistochemically, a significantly increased total vessel area (p < 0.001 for H&E, p = 0.037 for alphaSMA) and brightness integration (p = 0.047) for BSM+ in comparison to the native material were seen. Conclusions: The combination of a xenogenic bone-substitute material with hyaluronic acid significantly induced angiogenesis in vivo. This might lead to a faster integration and an improved healing in clinical situations.

Anti-chloride Intracellular Channel Protein 1 (CLIC1) Antibodies Induce Tumour Necrosis and Angiogenesis Inhibition on In Vivo Experimental Models of Human Renal Cancer.

BACKGROUND/AIM: Chloride intracellular channel protein 1 (CLIC1) is known as a promoter of cancer progression, metastasis, and angiogenesis. Thus, CLIC1 could be a future therapeutic target. This study aimed to evaluate the effect of anti-CLIC1 antibodies on tumour cells and vessels of human renal cell carcinoma (RCC) in rabbit cornea and chick embryo chorioallantoic membrane (CAM) models. MATERIALS AND METHODS: Human cc-RCC xenografts on rabbit cornea and CAM surface were performed. Anti-CLIC1 antibodies were applied for 5 consecutive days on both tumor models. We comparatively evaluated treated and untreated tumors by combining ultrasonography with microscopic techniques. RESULTS: RCC implants rapidly recruited blood vessels and had an exponential growth rate on both tumor models. Anti-CLIC1 antibodies suppressed tumor growth by inducing tumor cell necrosis. Tumor vessels regressed rapidly but not completely during anti-CLIC1 antibodies based therapy. CONCLUSION: Anti-CLIC1 antibodies induced tumor necrosis and tumor vasculature regression in human cc-RCC xenografts in both in vivo experimental models.

Saikosaponin A, a Triterpene Saponin, Suppresses Angiogenesis and Tumor Growth by Blocking VEGFR2-Mediated Signaling Pathway.

Saikosaponin A (SSA), a main triterpenoid saponin component from Radix Bupleurum, has been revealed to have a variety of pharmacological activities. However, whether SSA can inhibit angiogenesis, a key step in solid tumor progression, remains unknown. In this study, we demonstrated that SSA could powerfully suppress the proliferation, migration, and tube formation of human umbilical vein endothelial cells. SSA also significantly inhibited angiogenesis in the models of the chick embryo chorioallantoic membrane and Matrigel plugs. Moreover, SSA was found to inhibit tumor growth in both orthotopic 4T1 breast cancer and subcutaneous HCT-15 colorectal tumor by the inhibition of tumor angiogenesis. Western blot assay indicated the antiangiogenic mechanism of SSA in the suppression of the protein phosphorylation of VEGFR2 and the downstream protein kinase including PLCγ1, FAK, Src, and Akt. In summary, SSA can suppress angiogenesis and tumor growth by blocking the VEGFR2-mediated signaling pathway.

Liver Metastatic Colorectal Tumor Cells Change Their Phenotype During Consecutive Passages on Chick Embryo Chorioallantoic Membrane: Lessons from the Lab to the Clinic.

BACKGROUND/AIM: Colon cancer liver metastases with desmoplastic growth pattern (dGP) have a highly heterogeneous therapy response. The aim of the study was to evaluate the dGP liver metastasis molecular profile from a chemo-naive patient by mimicking metastatic process on an experimental chick embryo chorioallantoic membrane (CAM) model. MATERIALS AND METHODS: Three successive CAM passages of dGP human colorectal liver metastases were immunophenotyped for keratin (K) 8, and 20, CLIC1, VEGF, EGFR, CD34, podoplanin, Ki67, E-cadherin and vimentin. RESULTS: Metastatic cells gradually lost K20 while K8, E-cadherin and vimentin heterogeneously increased during passages. VEGF, CLIC 1, EGFR expression increased in metastatic cells especially at the tumor graft periphery. Scattered proliferating and non-proliferating podoplanin-positive tumor cells, lymphatic and blood vessels were heterogeneously detected in tumor xenografts depending on passage stage. CONCLUSION: By mimicking repetitive metastatic processes we proved that metastatic cells change their phenotype. This may explain why not all metastases have a similar response to therapy.

Pharmacologically targeting molecular motor promotes mitochondrial fission for anti-cancer.

Mitochondrial shape rapidly changes by dynamic balance of fusion and fission to adjust to constantly changing energy demands of cancer cells. Mitochondrial dynamics balance is exactly regulated by molecular motor consisted of myosin and actin cytoskeleton proteins. Thus, targeting myosin-actin molecular motor is considered as a promising strategy for anti-cancer. In this study, we performed a proof-of-concept study with a natural-derived small-molecule J13 to test the feasibility of anti-cancer therapeutics via pharmacologically targeting molecular motor. Here, we found J13 could directly target myosin-9 (MYH9)-actin molecular motor to promote mitochondrial fission progression, and markedly inhibited cancer cells survival, proliferation and migration. Mechanism study revealed that J13 impaired MYH9-actin interaction to inactivate molecular motor, and caused a cytoskeleton-dependent mitochondrial dynamics imbalance. Moreover, stable isotope labeling with amino acids in cell culture (SILAC) technology-coupled with pulldown analysis identified HSPA9 as a crucial adaptor protein connecting MYH9-actin molecular motor to mitochondrial fission. Taken together, we reported the first natural small-molecule directly targeting MYH9-actin molecular motor for anti-cancer translational research. Besides, our study also proved the conceptual practicability of pharmacologically disrupting mitochondrial fission/fusion dynamics in human cancer therapy.

Determination of the LD50 with the chick embryo chorioallantoic membrane (CAM) assay as a promising alternative in nanotoxicological evaluation.

Toxicity tests in rodents are still considered a controversial topic concerning their ethical justifiability. The chick embryo chorioallantoic membrane (CAM) assay may offer a simple and inexpensive alternative. The CAM assay is easy to perform and has low bureaucratic hurdles. At the same time, the CAM assay allows the application of a broad variety of analytical methods in the field of nanotoxicological research. We evaluated the CAM assay as a methodology for the determination of nanotoxicity. Therefore we calculated the median lethal dose (LD50), performed in vivo microscopy and immunohistochemistry to identify organ-specific accumulation profiles, potential organ damage, and the kinetics of the in vivo circulation of the nanoparticles. Zinc oxide nanoparticles were intravascularly injected on day 10 of the egg development and showed an LD50 of 17.5 µM (1.4 µg/mLeggcontent). In comparison, the LD50 of equivalent amounts of Zn2+ was 4.6 µM (0.6 µg/mLeggcontent). Silica encapsulated ZnO@SiO2 nanoparticles conjugated with fluorescein circulated in the bloodstream for at least 24 h. Particles accumulated mostly in the liver and kidney. In immunohistochemical staining, organ damage was detected only in liver tissue after intravascular injection of zinc oxide nanoparticles in very high concentrations. Zinc oxide nanoparticles showed a different pharmacokinetic profile compared to Zn2+ ions. In conclusion, the CAM assay has proven to be a promising methodology for evaluating nanotoxicity and for the assessment of the in vivo accumulation profiles of nanoparticles. These findings may qualify the methodology for risk assessment of innovative nanotherapeutics in the future.

Pharmacologically targeting molecular motor promotes mitochondrial fission for anti-cancer

Mitochondrial shape rapidly changes by dynamic balance of fusion and fission to adjust to constantly changing energy demands of cancer cells. Mitochondrial dynamics balance is exactly regulated by molecular motor consisted of myosin and actin cytoskeleton proteins. Thus, targeting myosin-actin molecular motor is considered as a promising strategy for anti-cancer. In this study, we performed a proof-of-concept study with a natural-derived small-molecule J13 to test the feasibility of anti-cancer therapeutics

The Potential Use of Electrochemotherapy in the Treatment of Uveal Melanoma: In Vitro Results in 3D Tumor Cultures and In Vivo Results in a Chick Embryo Model.

Uveal melanoma (UM) is the most common primary intraocular tumor that arises from neoplastic melanocytes in the choroid, iris, and ciliary body. Electrochemotherapy (ECT) has been successfully established for the treatment of skin and soft tissue metastatic lesions, deep-seated tumors of the liver, bone metastases, and unresectable pancreas lesions. The aim of this study was to evaluate the effect of ECT in vitro in 3D spheroid culture systems in primary and metastatic UM cell lines. We also investigated the chick embryo chorioallantoic membrane (CAM) as an in vivo model system for the growth and treatment of UM tumors using ECT. The cytotoxic effect of ECT in 3D spheroids was analyzed seven days following treatment by assessment of the size and MTT [(3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) tetrazolium reduction] assay. The cytotoxicity of ECT after intratumoral or intraarterial administration was evaluated histologically. In vitro and in vivo ECT caused a significant reduction in tumor size and viability compared to electroporation or chemotherapy in both sections of our study. The current results underline the effectiveness of ECT in the treatment of UM and prepare the way for further investigation of its potential application in UM.

Effect of local aromatase inhibition in endometriosis using a new chick embryo chorioallantoic membrane model.

Endometriosis is an oestrogen-dependent, inflammation-driven gynaecologic disorder causing severe disability. Endometriosis implants are characterized by unbalanced local oestrogen metabolism leading to hyperoestrogenism and aromatase up-regulation is one of main mechanism involved. Aromatase inhibitors such as letrozole or anastrozole use in young women are associated with severely side effects limiting their long-term clinical use. An endometriosis-targeted inhibition of local aromatase could be a viable alternative, although the role of the local inhibition of this enzyme is still unclear. Using a new chick embryo allantoic membrane (CAM) model incorporating xenografted human endometriosis cyst, we showed that topical treatment with anastrozole reduced lesion size, although oestrogens produced by CAM female embryo blunted this effect. Xenografted human endometriosis CAM is a new efficient model for the screening of new drugs targeting endometriosis tissue.

Disodium Cromolyn and Anti-podoplanin Antibodies Strongly Inhibit Growth of BHK 21/C13-derived Fibrosarcoma in a Chick Embryo Chorioallantoic Membrane Model.

AIM: To characterize baby hamster kidney fibroblast (BHK 21/C13) cells and test the effects of antibodies against podoplanin and disodium cromolyn on BHK 21/C13 cell line-derived tumors grown on chick embryo chorioallantoic membrane (CAM). MATERIAL AND METHODS: BHK 21/C13 cell-derived fibrosarcomas developed in hamsters were implanted on CAM and treated with anti-podoplanin antibodies and disodium cromolyn. BHK 21/C13 cell immunophenotype was assessed. RESULTS: Fibrosarcoma cells were positive for vimentin, CD117, smooth muscle actin, vascular endothelial growth factor epidermal growth factor receptor, homebox prospero gene 1 and negative for platelet-derived growth factor B, neuron-specific enolase, S100, CD34, Ewing sarcoma and podoplanin. CAM-grown fibrosarcomas were highly sensitive to disodium cromolyn and anti-podoplanin antibodies. CONCLUSION: Immunophenotyping BHK 21/C13 cells and their response to drugs represent the first step in revealing cell line utility and a reliable tool for experimental cancer research.

Natalizumab reduces serum pro-angiogenic activity in MS patients.

Angiogenesis has been implicated in the pathobiology of multiple sclerosis (MS). Osteopontin exerts a pro-angiogenetic effect and is increased in body fluid of MS patients. To evaluate the effect of 1 year natalizumab treatment on serum pro-angiogenic activity and on plasma osteopontin levels in relapsing (RR) MS patients. Ten RRMS patients scheduled for natalizumab treatment were enrolled and evaluated at baseline and after 1-year natalizumab treatment. Pro-angiogenic activity was assessed by a chick embryo chorioallantoic membrane assay (CAM), osteopontin levels were evaluated by an enzyme-linked immunosorbent assay. Plasma and serum samples of 10 treatment-naïve RRMS and 10 healthy controls (HCs) were used as controls of baseline evaluations. Both treatment-naïve and natalizumab scheduled RRMS patients had higher baseline vessel density (22.0 ± 3.9 and 22.5 ± 2.6, p < 0.0001) and higher osteopontin levels (65.7 ± 24.3 ng/ml and 65.9 ± 16.6 ng/ml, p = 0.019 and p = 0.029, respectively) than HCs (9.0 ± 2.2; 48.5 ± 7.8 ng/ml, respectively). Baseline osteopontin levels and vessel density were significantly correlated (rs = 0.373, p = 0.043). After 1 year of treatment, the number of vessels and the osteopontin levels, were significantly reduced (11.9 ± 2.1, p < 0.005; 49.3 ± 20.0 ng/ml, p = 0.028). Our results suggest that natalizumab could exert its anti-inflammatory properties also by inhibiting the angiogenetic mechanisms in RRMS patients.

Alantolactone, a sesquiterpene lactone, inhibits breast cancer growth by antiangiogenic activity via blocking VEGFR2 signaling.

Alantolactone (ALA), a sesquiterpene lactone isolated from several medicinal plants such as Inula helenium, has been identified to have attractive anticancer activity. However, its role in the inhibition of angiogenesis during tumor development remains unclear. In this study, we found ALA can inhibit the proliferation, motility, migration, and tube formation of human umbilical vein endothelial cells. ALA also restrained angiogenesis in chick embryo chorioallantoic membrane and delayed the growth of human MDA-MB-231 breast cancer xenograft in mice through angiogenesis inhibition. Furthermore, ALA suppressed the phosphorylation of vascular endothelial growth factor receptor 2 and its downstream protein kinase including PLCγ1, FAK, Src, and Akt in endothelial cells. Taken together, the antiangiogenic activity of ALA and its molecular mechanism are identified for the first time, indicating that ALA may be a potential drug candidate or lead compound for antiangiogenic cancer therapy.

Transplantation of human neonatal foreskin stromal cells in ex vivo organotypic cultures of embryonic chick femurs.

We have previously reported that human neonatal foreskin stromal cells (hNSSCs) promote angiogenesis in vitro and in chick embryo chorioallantoic membrane (CAM) assay in vivo. To examine the in vivo relevance of this observation, we examined in the present study the differentiation potential of hNSSCs in ex vivo organotypic cultures of embryonic chick femurs. Isolated embryonic chick femurs (E10 and E11) were cultured for 10 days together with micro-mass cell pellets of hNSSCs, human umbilical vein endothelial cells (HUVEC) or a combination of the two cell types. Changes in femurs gross morphology and integration of the cells within the femurs were investigated using standard histology and immunohistochemistry. After 10 days, the femurs that were cultured in the presence of hNSSCs alone or hNSSC + HUVEC cells grew longer, exhibited thicker diaphysis and an enlarged epiphyseal region compared to control femurs cultured in the absence of cells. Analysis of cell-femur interactions, revealed intense staining for CD31 and enhanced deposition of collagen rich matrix along the periosteum in femurs cultured with hNSSCs alone or hNSSCs + HUVEC and the most pronounced effects were observed in hNSSC + HUVEC cultures. Our data suggest that organotypic cultures can be employed to test the differentiation potential of stem cells and demonstrate the importance of stem cell interaction with 3D-intact tissue microenvironment for their differentiation.

Effect of angiogenesis on Solanine and VEGF antibody in chicken embryo transplantation model of human colon cancer cells / 重庆医学

Objective To establish model of the chicken embryo transplantation of human colon cancer cells ,and investigate the effect of Solanine、VEGF antibody and Solanine combined with VEGF antibody on human colon cancer cells induce tumor angio‐genesis and tumor proliferation .Methods The model of the chicken embryo transplantation of human colon cancer HT‐29 cells were divided into three experimental group and control group .We added to the chick embryo chorioallantoic membrane with Sola‐nine、VEGF antibody and Solanine+ VEGF antibody mixture ,PBS was added to the control group .Then we analysed picture through the stereomicroscope and IPP 6 .0 image analysis software ,using immunohistochemistry envision method to detect of CD34 antigen and ki‐67 antigen ,and observing effect of Solanine group ,VEGF antibody group ,Solanine+ VEGF antibody group and the effect on the tumor angiogenesis and tumor proliferation .Results The tumor angiogenesis ,CD34 antigen and ki‐67 antigen of Sola‐nine+VEGF antibody group were significantly better than those of VEGF antibody group and Solanine group(P<0 .01);VEGF antibody group had statistical significant difference with Solanine group(P<0 .01);the effect of other three groups were better than that of the control group(P<0 .01) .Conclusion Solanine、VEGF antibody and Solanine combined with VEGF antibody could in‐hibit tumor angiogenesis and tumor proliferation of human colon cancer cell line HT‐29 to induce .It provides a new way for anti‐an‐giogenes .

Endostatin Effects on Tumor Cells and Vascular Network of Human Renal Cell Carcinoma Implanted on Chick Embryo Chorioallantoic Membrane.

Rare and inconsistent data are reported for chorioallantoic tumor models of renal cell carcinoma and none of them has used endostatin as an inhibitory agent of tumor development. We aimed to perform a comparative analysis of tumor cells and blood vessels from renal cell carcinoma on endostatin-treated and non-treated chorioallantoic membrane (CAM) implants by the assessment of endoglin, vascular endothelial growth factor (VEGF) and smooth muscle actin expression. Endostatin triple action on tumor, endothelial and perivascular cells was observed in the present study. Differential impact of endostatin treatment on intratumor and peritumor blood vessels was noticed on the VEGF expression and behaviour of tumor cells between clear cell and papillary components of RCC. Based on our findings, a high tumor heterogenity response to endostatin has been highlighted. Interplay between VEGF, endoglin and endostatin in RCC could support a combined targeted therapy to improve prognosis of patients with RCC and reduce therapy resistance often developed by monotherapy.

Platycodin D inhibits tumor growth by antiangiogenic activity via blocking VEGFR2-mediated signaling pathway.

Platycodin D (PD) is an active component mainly isolated from the root of Platycodon grandiflorum. Recent studies proved that PD exhibited inhibitory effect on proliferation, migration, invasion and xenograft growth of diverse cancer cell lines. However, whether PD is suppressive for angiogenesis, an important hallmark in cancer development, remains unknown. Here, we found that PD could dose-dependently inhibit human umbilical vein endothelial cell (HUVEC) proliferation, motility, migration and tube formation. PD also significantly inhibited angiogenesis in the chick embryo chorioallantoic membrane (CAM). Moreover, the antiangiogenic activity of PD contributed to its in vivo anticancer potency shown in the decreased microvessel density and delayed growth of HCT-15 xenograft in mice with no overt toxicity. Western blot analysis indicated that PD inhibited the phosphorylation of VEGFR2 and its downstream protein kinase including PLCγ1, JAK2, FAK, Src, and Akt in endothelial cells. Molecular docking simulation showed that PD formed hydrogen bonds and hydrophobic interactions within the ATP binding pocket of VEGFR2 kinase domain. The present study firstly revealed the high antiangiogenic activity and the underlying molecular basis of PD, suggesting that PD may be a potential antiangiogenic agent for angiogenesis-related diseases.

Fibromodulin promoted in vitro and in vivo angiogenesis.

Fibromodulin (FMOD) is an extracellular matrix (ECM) small leucine-rich proteoglycan (SLRP) that plays an important role in cell fate determination. Previous studies revealed that not only is FMOD critical in fetal-type scarless wound healing, but it also promotes adult wound closure and reduces scar formation. In addition, FMOD-deficient mice exhibit significantly reduced blood vessel regeneration in granulation tissues during wound healing. In this study, we investigated the effects of FMOD on angiogenesis, which is an important event in wound healing as well as embryonic development and tumorigenesis. We found that FMOD accelerated human umbilical vein endothelial HUVEC-CS cell adhesion, spreading, actin stress fiber formation, and eventually tube-like structure (TLS) network establishment in vitro. On a molecular level, by increasing expression of collagen I and III, angiopoietin (Ang)-2, and vascular endothelial growth factor (VEGF), as well as reducing the ratio of Ang-1/Ang-2, FMOD provided a favorable network to mobilize quiescent endothelial cells to an angiogenic phenotype. Moreover, we also confirmed that FMOD enhanced angiogenesis in vivo by using an in ovo chick embryo chorioallantoic membrane (CAM) assay. Therefore, our data demonstrate that FMOD is a pro-angiogenic and suggest a potential therapeutic role of FMOD in the treatment of conditions related to impaired angiogenesis.

Behavior of the P1.HTR mastocytoma cell line implanted in the chorioallantoic membrane of chick embryos

The P1.HTR cell line includes highly transfectable cells derived from P815 mastocytoma cells originating from mouse breast tissue. Despite its widespread use in immunogenic studies, no data are available about the behavior of P1.HTR cells in the chick embryo chorioallantoic membrane model. The objective of the present investigation was to study the effects of P1.HTR cells implanted on the chorioallantoic membrane of chick embryos. We inoculated P1.HTR cells into the previously prepared chick embryo chorioallantoic membrane and observed the early and late effects of these cells by stereomicroscopy, histochemistry and immunohistochemistry. A highly angiotropic and angiogenic effect occurred early after inoculation and a tumorigenic potential with the development of mastocytoma keeping well mast cells immunophenotype was detected later during the development. The P1.HTR mastocytoma cell line is a good tool for the development of the chick embryo chorioallantoic membrane mastocytoma model and also for other studies concerning the involvement of blood vessels. The chick embryo chorioallantoic membrane model of mastocytoma retains the mast cell immunophenotype under experimental conditions and could be used as an experimental tool for in vivo preliminary testing of antitumor and antivascular drugs.