Tag Archives: angiogenesis

Plasminogen modulates formation and release of platelet angiogenic regulators

A. A. Tykhomyrov, D. D. Zhernosekov, T. V. Grinenko

Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv;
e-mail: artem_tykhomyrov@ukr.net

Received: 19 July 2019; Accepted: 29 November 2019

Platelets store, produce and release a variety of angiogenesis regulators, which can contribute to both normal tissue repair and angiopathy-associated pathologies. Plasminogen has been earlier shown to regulate some platelet functions, but if it is able to modulate angiogenic capacities of platelets is still poorly studied. Thus, the aim of the present study was to evaluate the effects of different plasminogen forms on the formation and secretion of angiogenic protein regulators by platelets. Human washed platelets were obtained by gel-filtration on Sepharose-2B. The levels of P-selectin (CD-62P) exposed on the plasma membrane of untreated and activated platelets was monitored by flow cytometry. Secretion of platelet-derived vascular endothelial growth factor (VEGF) as well as plasminogen fragmentation and angiostatin formation by intact platelets and platelet plasma membranes were analyzed by immunoblotting. It was shown that thrombin or collagen exposure resulted in enhanced P-selectin surface expression by platelets, while Lys-form of plasminogen reduced agonist-induced platelet secretion. Lys-plasminogen, but not Glu-form, inhibited agonist-induced VEGF release from platelets. Activation of platelets significantly accelerated plasminogen cleavage and angiostatin formation. Anti-actin antibodies inhibited plasminogen fragmentation during incubation with platelet plasma membranes indicating surface-exposed actin participation  in plasminogen conversion to angiostatins. The present study uncovers a novel function of plasminogen to limit angiogenic potential of platelets via angiostatin formation and inhibition of VEGF secretion.

The mechanism of VEGF-mediated endothelial cells survival and proliferation in conditions of unfed-culture

T. V. Nikolaienko, V. V. Nikulina, D. V. Shelest, L. V. Garmanchuk

Educational and Scientific Centre “Institute of Biology”,
Taras Shevchenko National University of Kyiv, Ukraine;
e-mail: nikolaenkotetiana@yandex.ua

The mechanisms of VEGF-mediated effects on endothelial cells during cancer development and progression is not clear. In present study the biological effects of VEGF, VEGF-rich culture medium of peritoneal macrophages from mice with Lewis lung carcinoma were studied on MAEC cell line under conditions of unfed culture. We have shown that VEGF increased cell proliferation by the 5th day of culturing vs control and anti-VEGF-treated cells. This effect was associated with increased consumption of glucose and NO production by the 2nd day while decreased – on the 5th day of cell culturing. VEGF-mediated NO production was dependent on Ca2+ ions. Block of Ca2+-channels (LaCl3) had more pronounced inhibitory effect vs chelator of Ca2+ ions (EDTA).  It was shown that peritoneal macrophages are the main suppliers of VEGF at tumor angiogenesis, as evidenced by the data obtained on model system of endothelial cells synchronized in G0/G1 phase.

Role of plasminogen/plasmin in functional activity of blood cells

D. D. Zhernossekov, E. I. Yusova, T. V. Grinenko

Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv;
e-mail:grinenko@biochem.kiev.ua

The article deals with the data concerning structural peculiarities of plasminogen/plasmin molecule, which define the specificity of intermolecular interactions and provide the variety of its biological functions. The main principles of the modern classification of plasminogen receptors and factors, which modulate their expression, have been presented. We have considered the mechanisms regulating both plasmin formation and activity on the surface of cells, fibrin and proteins of extracellular matrix. The data of previous investigators and our own results, concerning the influence of plasminogen/plasmin on platelet aggregation induced by different agonists, have been summarized. The participation of plasminogen/plasmin in atherogenesis and angiogenesis mediated­ by endotheliocyte receptors has been discussed. Special attention was given to plasminogen/plasmin pro-inflammatory function, which is realized by regulatory processes of activation, secretion, migration and apoptosis of monocytes and macrophages.

Role of multidomain structure of urokinase in regulation of growth and remodeling of vessels

V. A. Tkachuk1,2, O. S. Plekhanova1, I. B. Beloglazova1, E. V. Parfenova1

1Russian Cardiologic Research-Production Complex,
RF Ministry of Public Health, Moscow, Russia;
2Faculty of Fundamental Medicine, M.V. Lomonosov Moscow
State University, Russia;
e-mail: plekhanova@mail.ru

Urokinase type plasminogen activator, or urokinase (uPA), is a multifunctional protein which plays special regulatory role in the vascular wall and can actuate the proteolytic and signal cascades. The authors’ results and literature data concerning the role of urokinase in remodeling blood vessels and angiogenesis are summarized in the paper. At the present stage urokinase may be conside­red as a promising target for the effects directed to prophylaxis of restenoses, to preventing of negative remodeling of arteries­, stimulation of vessels growth under the ischemic diseases and suppression of angiogenesis under oncologic diseases.

Plasminogen and angiostatin levels in female benign breast lesions

A. A. Tykhomyrov1, I. L. Vovchuk2, T. V. Grinenko1

1Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv;
2Odessa I. I. Mechnikov National University, Ukraine;
e-mail: artem_tykhomyrov@ukr.net

It is known that benign breast tissue exhibit relatively low angiogenic capacity. Activation of angiogenesis in mammary pre-malignant lesions could be associated with disease progression and high risk of transformation into the breast cancer. However, insight into the underlying molecular mechanisms involved in angiogenesis regulation in non-cancerous breast pathologies is still poorly defined. The purpose of the present study was to determine levels of plasminogen and its proteolytic fragments (angiostatins) in mammary dysplasia (mastopathy and breast cyst) and benign neoplasms (fibroadenomas). Plasminogen and angiostatins were analyzed using immunoblotting and quantified by densitometric scanning. The significant increase in plasminogen levels was found in fibrocystic, cysts, and non-proliferatious fibroadenoma masses (4.7-, 3.7-, and 3.5-fold, respectively) compared to healthy breast tissues (control). In the same benign lesions, 6.7-, 4-, and 3.7-fold increase in plasminogen 50 kDa fragment (angiostatin) levels as compared with control were also observed. Activation of matrix metalloproteinase-9, which was detected using gelatine zymography, could be responsible for plasminogen cleavage and abundance of angiostatin in fibrocystic and cyst masses. In contrast, dramatic decrease of both plasminogen and angiostatin levels (3.8- and 5.3-folds, respectively) was shown in tissues of proliferatious form of fibroadenoma in comparison with that of the dormant type of this neoplasm. Based on the obtained results, we concluded that angiostatin, a potent vessel growth inhibitor and anti-inflammatory molecule, can play a crucial role in pathophysiology of non-cancerous breast diseases. Further studies are needed to evaluate potential diagnostic and clinical implications of these proteins for prediction and therapy of benign breast pathologies.