Galectin-8 Favors VEGF-Induced Angiogenesis: In Vitro Study in Human Umbilical Vein Endothelial Cells and In Vivo Study in Chick Chorioallantoic Membrane

BACKGROUND/AIM

Although it has been accepted that the tandem repeat galectin-8 (Gal-8) is linked to angiogenesis, the underlying mechanisms in endothelial cells has remained poorly understood. In this study we aimed to investigate the effect of Gal-8 on selected biological processes linked to angiogenesis in in vitro and in vivo models.

MATERIALS AND METHODS

In detail, we assessed how exogenously added human recombinant Gal-8 (with or without vascular endothelial growth factor - VEGF) affects selected steps involved in vessel formation in human umbilical vein endothelial cells (HUVECs) as well as using the chick chorioallantoic membrane (CAM) assay. Gene expression profiling of HUVECs was performed to extend the scope of our investigation.

RESULTS

Our findings demonstrate that Gal-8 in combination with VEGF enhanced cell proliferation and migration, two cellular events linked to angiogenesis. However, Gal-8 alone did not exhibit any significant effects on cell proliferation or on cell migration. The molecular analysis revealed that Gal-8 in the presence of VEGF influenced cytokine-cytokine receptor interactions, HIF-1 and PI3K/AKT signaling pathways. Gal-8 alone also targeted cytokine-cytokine receptor interactions, but with a different expression profile as well as a modulated focal adhesion and TNF signaling.

CONCLUSION

Gal-8 promotes a pro-angiogenic phenotype possibly in a synergistic manner with VEGF.

Genistein Improves Skin Flap Viability in Rats: A Preliminary In Vivo and In Vitro Investigation

Selective estrogen receptor modulators (SERMs) have been developed to achieve beneficial effects of estrogens while minimizing their side effects. In this context, we decided to evaluate the protective effect of genistein, a natural SERM, on skin flap viability in rats and in a series of in vitro experiments on endothelial cells (migration, proliferation, antioxidant properties, and gene expression profiling following genistein treatment). Our results showed that administration of genistein increased skin flap viability, but importantly, the difference is only significant when treatment is started 3 days prior the flap surgery. Based on our in vitro experiments, it may be hypothesized that the underlying mechanism may rather by mediated by increasing SOD activity and Bcl-2 expression. The gene expression profiling further revealed 9 up-regulated genes (angiogenesis/inflammation promoting: CTGF, CXCL5, IL-6, ITGB3, MMP-14, and VEGF-A; angiogenesis inhibiting: COL18A1, TIMP-2, and TIMP-3). In conclusion, we observed a protective effect of genistein on skin flap viability which could be potentially applied in plastic surgery to women undergoing a reconstructive and/or plastic intervention. Nevertheless, further research is needed to explain the exact underlying mechanism and to find the optimal treatment protocol.

β-Escin Effectively Modulates HUVECS Proliferation and Tube Formation

In the present study we evaluated the anti-angiogenic activities of β-escin (the major active compound of Aesculus hippocastanum L. seeds). Human umbilical-vein endothelial cells (HUVECs) were used as an in vitro model for studying the molecular mechanism underlying the anti-angiogenic effect of β-escin. We investigated the in vitro effects on proliferation, migration, and tube formation of HUVECs and in vivo anti-angiogenic activity was evaluated in a chick chorioallantoic membrane (CAM) angiogenesis assay. Moreover, the effect on gene expressions was determined by the RT2 ProfilerTM human angiogenesis PCR Array. It was found that β-escin exerts inhibitory effect on the basic fibroblast growth factor (bFGF)-induced proliferation, migration and tube formation, as well as CAM angiogenesis in vivo. The inhibition of critical steps of angiogenic process observed with β-escin could be partially explained by suppression of Akt activation in response to bFGF. Moreover, the anti-angiogenic effects of β-escin could also be mediated via inhibition of EFNB2 and FGF-1 gene expressions in endothelial cells. In conclusion, β-escin affects endothelial cells as a negative mediator of angiogenesis in vitro and in vivo and may therefore be considered as a promising candidate for further research elucidating its underlying mechanism of action.

Agrimonia eupatoria L. and Cynara cardunculus L. Water Infusions: Phenolic Profile and Comparison of Antioxidant Activities

Reactive oxygen species (ROS) are highly considered in the ethiopathogenesis of different pathological conditions because they may cause significant damage to cells and tissues. In this paper, we focused on potential antioxidant properties of two medical plants such as the Agrimonia eupatoria L. and Cynara cardunculus L. Both plants have previously been studied for their pharmacological activities, especially as hepatoprotective and hypoglycemic activities. It has been suggested, that their effects are related to the antioxidant properties of polyphenols, which are dominant compounds of the plants’ extracts. In the present study HPLC-MS analysis of water infusion was performed allowing the identification of several phenolic constituents. Furthermore, antioxidant effects of the two extracts were compared showing higher effects for agrimony extract compared to artichoke. Thus, agrimony was selected for the in vivo study using the skin flap viability model. In conclusion, our results provide evidence that the A. eupatoria extract may be a valuable source of polyphenols to be studied for the future development of supplements useful in the prevention of diseases linked to oxidative stress.

Pharmacological activation of estrogen receptors-α and -β differentially modulates keratinocyte differentiation with functional impact on wound healing

Estrogen deprivation is considered responsible for many age-related processes, including poor wound healing. Guided by previous observations that estradiol accelerates re‑epithelialization through estrogen receptor (ER)‑β, in the present study, we examined whether selective ER agonists [4,4',4''-(4-propyl [1H] pyrazole-1,3,5-triyl)‑trisphenol (PPT), ER‑α agonist; 2,3-bis(4-hydroxyphenyl)-propionitrile (DPN), ER‑β agonist] affect the expression of basic proliferation and differentiation markers (Ki‑67, keratin‑10, ‑14 and ‑19, galectin‑1 and Sox‑2) of keratinocytes using HaCaT cells. In parallel, ovariectomized rats were treated daily with an ER modulator, and wound tissue was removed 21 days after wounding and routinely processed for basic histological analysis. Our results revealed that the HaCaT keratinocytes expressed both ER‑α and ‑β, and thus are well-suited for studying the effects of ER agonists on epidermal regeneration. The activation of ER‑α produced a protein expression pattern similar to that observed in the control culture, with a moderate expression of Ki‑67 being observed. However, the activation of ER‑β led to an increase in cell proliferation and keratin‑19 expression, as well as a decrease in galectin‑1 expression. Fittingly, in rat wounds treated with the ER‑β agonist (DPN), epidermal regeneration was accelerated. In the present study, we provide information on the mechanisms through which estrogens affect the expression patterns of selected markers, thus modulating keratinocyte proliferation and differentiation; in addition, we demonstrate that the pharmacological activation of ER-α and -β has a direct impact on wound healing.

Extracellular matrix of galectin-1-exposed dermal and tumor-associated fibroblasts favors growth of human umbilical vein endothelial cells in vitro: a short report

BACKGROUND/AIM

Stromal cells in the tumor microenvironment are primarily considered as sources of promalignant factors. The objective of our study was to define the effect of extracellular matrix (ECM) produced by normal dermal or cancer-associated fibroblasts exposed to adhesion/growth-regulatory lectin galectin-1 on human umbilical vein endothelial cells (HUVECs).

MATERIALS AND METHODS

Fibroblasts were cultured for 10 days with lectin, followed by removing cellular constituents after an osmotic shock. Freshly-isolated HUVECs were placed on the ECM. In parallel, HUVECs were seeded on untreated and gelatin-coated surfaces as controls. A positive control for growth of HUVECs culture using medium supplemented with vascular endothelial growth factor completed the test panel. Cells were kept in contact to the substratum for two days and then processed for immunocytochemistry.

RESULTS

HUVECs seeded on fibroblast-generated ECM presented a comparatively high degree of proliferation. Furthermore, contact to substratum produced by tumor-associated fibroblasts led to generation of a meshwork especially rich in fibronectin.

CONCLUSION

Galectin-1 is apparently capable to trigger ECM production favorable for growth of HUVECs, prompting further work on characterizing structural features of the ECM and in situ correlation of lectin presence, ECM constitution and neoangiogenesis.

[Basic biological roles of galectins in tissue repair and tumor growth]

Galectins are representatives of endogenous lectins - molecules specifically recognizing distinct sugar motifs. They play an important role in the processes of cell proliferation, differentiation, migration and extracellular matrix formation. Furthermore, galectins are able to transfer cellular signals and to participate in intercellular interaction. It has been proven that galectins play an important role in the formation of tumor and/or wound healing microenvironment. This review contains an overview of experimental and clinical studies dealing with biological roles of galectins in tissue repair and in its parallel - the tumor growth.

Human erythropoietin increases the pro-angiogenic potential of A2780 ovarian adenocarcinoma cells under hypoxic conditions

Erythropoietin (Epo) is a key regulator of erythroid cell proliferation, differentiation and apoptosis. In the form of the recombinant protein, it is widely used to treat various types of anemias, including that associated with cancer and with the myelosuppressive effects of chemotherapy, particularly platinum-based regimens. Our previous studies confirmed the presence of Epo receptors (EpoRs) in ovarian adenocarcinoma cell lines and demonstrated that long-term Epo treatment of A2780 cells resulted in the development of a phenotype exhibiting both enhanced Epo signaling and increased paclitaxel resistance. In the present study, we carried out a series of experiments to analyze the pro-angiogenic potential of Epo-treated A2780 and SKOV-3 cells. Our studies revealed that conditioned media of Epo-treated A2780 cells had a stimulative effect on human umbilical vein endothelial cells (HUVECs). This effect was only seen when A2780 cells were incubated under hypoxic conditions. Furthermore, Epo increased the secretion of interleukin (IL)-4, IL-5, IL-6, IL-8, IL-10, IL-12, IL-13, GM-CSF and interferon-γ by A2780 cells that grew in hypoxic conditions. In this regard, conditioned media of hypoxic and Epo-treated A2780 cells induced a significant phosphorylation of STAT-5 in HUVECs. Our results may have important implications for ovarian cancer patients receiving Epo.

Synthesis, self-aggregation and biological properties of alkylphosphocholine and alkylphosphohomocholine derivatives of cetyltrimethylammonium bromide, cetylpyridinium bromide, benzalkonium bromide (C16) and benzethonium chloride

A series of alkylphosphocholine and alkylphosphohomocholine derivatives of cetyltrimethylammonium bromide, cetylpyridinium bromide, benzalkonium bromide (C16) and benzethonium chloride have been synthesized. Their physicochemical properties were also investigated. The critical micelle concentration (cmc), the surface tension value at the cmc (γcmc), and the surface area at the surface saturation per head group (Acmc) were determined by means of surface tension measurements. The prepared compounds exhibit significant cytotoxic, antifungal and antiprotozoal activities. Alkylphosphocholines and alkylphosphohomocholines possess higher antifungal activity against Candida albicans in comparison with quaternary ammonium compounds in general. However, quaternary ammonium compounds exhibit significantly higher activity against human tumor cells and pathogenic free-living amoebae Acanthamoeba lugdunensis and Acanthamoeba quina compared to alkylphosphocholines. The relationship between structure, physicochemical properties and biological activity of the tested compounds is discussed.

Location and the functionality of erythropoietin receptor(s) in A2780 cells

Erythropoietin (Epo) is a critical regulator of erythroid cell proliferation, differentiation and apoptosis. In the form of a recombinant protein, it is widely used to treat various forms of anemia, including that associated with cancer and with the myelosuppressive effects of chemotherapy. Studies of ovarian cancer cell lines have demonstrated the presence of the Epo receptor (EpoR), but there are disagreements regarding its localization and functionality in these cells. Using fluorescence microscopy, we were not able to identify the EpoR on the surface of A2780 cells, in contrast to the positive control K562 cells. Flow cytometry did reveal a weak surface EpoR signal in A2780 cells. Interestingly, most of the EpoR in A2780 cells was found in the cytoplasm, more abundantly as an intracellular membrane-associated protein than a soluble one. Silencing EpoR expression by lentiviral-mediated shRNA resulted in reduced A2780 proliferation as well as reduction in Epo-induced phosphorylation of Erk1/2. Our findings provide important insights into the biology of the EpoR in ovarian cancer cells.

Antiproliferative and antiangiogenic properties of horse chestnut extract

This study was designed to examine the in vitro antiproliferative effect of the horse chestnut extract (HCE) on cancer cell lines. Furthermore, we have investigated the in vitro effect of HCE on some angiogenic events by using human umbilical vein endothelial cells. The cell proliferation was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and anchorage-independent growth by colony-forming assay. To understand the growth inhibitory effects, carcinoma cell lines (Jurkat, CEM, HeLa, and MCF-7) were treated with various concentrations of HCE. Incubation of Jurkat, CEM, HeLa, and MCF-7 cancer cells with HCE at 125 µg/mL for 72 h caused 93.7%, 32.3%, 20.4% and 40.4% reduction in cell survival. Colony-forming assay also confirmed growth-inhibitory effects of the compound studied. In HeLa HCE-treated cells, we found a significant increase in cells having sub-G(0) /G(1) DNA content which is considered to be a marker of apoptotic cell death. Apoptosis was also further confirmed by DNA fragmentation analysis.Furthermore, HCE inhibited migration of human umbilical vein endothelial cells as well as decreased secretion of matrix metalloproteinase and vascular endothelial growth factor.In conclusion, the present study has assessed the in vitro antiproliferative/antiangiogenic potential of HCE. These results generate a rationale for in vivo efficacy studies with horse chestnut in preclinical cancer models.

Anti-proliferative and anti-angiogenic effects of CB2R agonist (JWH-133) in non-small lung cancer cells (A549) and human umbilical vein endothelial cells: an in vitro investigation

Non-small cell lung cancer has one of the highest mortality rates among cancer-suffering patients. It is well known that the unwanted psychotropic effects of cannabinoids (CBs) are mediated via the CB(1) receptor (R), and selective targeting of the CB(2)R would thus avoid side effects in cancer treatment. Therefore, the aim of our study was to evaluate the effect of selective CB(2)R agonist, JWH-133, on A549 cells (non-small lung cancer) and human umbilical vein endothelial cells (HUVECs). Cytotoxicity assay and DNA fragmentation assay were employed to evaluate the influence of JWH-133 (3-(1,1-dimethylbutyl)- 1-deoxy-Δ8-tetrahydrocannabinol) on investigated cancer cells. In addition, migration assay and gelatinase zymography were performed in HUVECs to asses JWH-133 anti-angiogenic activity. Our study showed that JWH-133 exerted cytotoxic effect only at the highest concentration used (10(-4) mol/l), while inhibition of colony formation was also detected at the non-toxic concentrations (10(-5)-10(-8) mol/l). JWH-133 was also found to be able to induce weak DNA fragmentation in A549 cells. Furthermore, JWH-133 at non-toxic concentrations inhibited some steps in the process of angiogenesis. It significantly inhibited endothelial cell migration after 17 h of incubation at concentrations of 10(-4)-10(-6) mol/l. In addition, JWH-133 inhibited MMP-2 secretion as assessed by gelatinase zymography. The present study demonstrates the in vitro anti-proliferative and anti-angiogenic potential of CB(2)R agonist, JWH-133, in nonsmall lung cancer cells and HUVECs. Our results generate a rationale for further in vivo efficacy studies with this compound in preclinical cancer models.

Effect of selected flavones on cancer and endothelial cells

In our study we used quercetin (3,3 ,4 ,5,7-pentahydroxyflavone) as the reference standard to compare antiproliferative and antiangiogenic effects of chrysin (5,7-dihydroxyflavone) and 3-hydroxyflavone. Our data indicates that chrysin and 3-hydroxyflavone showed significantly higher cytotoxic effect than reference standard quercetin. These tested agents significantly decreased cell survival with the efficacy of 65-85% at the concentration 100 micromol/l for HUVEC, lung carcinoma and leukemic cells being the most sensitive. Cell cycle analysis indicates that quercetin and 3-hydroxyflavone might affect the cell cycle of Jurkat cells by a similar or the same mechanism of action which lead to G2/M arrest as well as to an increase in sub-G0/G1 fraction. Treatment of Jurkat cells with chrysin resulted only increase in the fraction of cells with sub-G0/G1 DNA content, which is considered to be a marker of apoptotic cell death. Apoptosis was confirmed by DNA fragmentation and by staining with annexin V. All three tested flavones inhibited endothelial cell migration after 24 h of incubation at a concentration 100 micromol/l. At a lower concentration (10 micromol/l) only quercetin significantly inhibited migration of endothelial cells. Furthermore, in our experiments decreased secretion of matrix metalloproteinases (MMP-2 and MMP-9) was observed after a 72 h treatment with quercetin. No decrease in secretion of MMP-2 and MMP-9 was seen after chrysin and 3-hydroxyflavone treatment. On the other hand, our results showed that none of three flavonoids blocked microcapillary tube formation. Further studies are necessary to investigate the mechanism of action and to find out the relationship between the structure, character and position of substituents of natural substances and their biological activities.

Rate of oxidative modification of cytochrome c by hydrogen peroxide is modulated by Hofmeister anions

Cytochrome c (cyt c) and other heme proteins are oxidatively modified in the presence of hydrogen peroxide in a concentration- and time-dependent manner. Cyt c modification has been monitored by several spectral probes by absorption spectroscopy (at wavelengths 410 nm, 530 nm), and circular dichroism (222, 268, 288 and 417 nm). Kinetics monitored with these spectral probes indicates that the oxidative modification of cyt c: i) proceeds in the order: heme --> aromatic amino acids --> secondary structure, and ii) the rate of the oxidative modification is proportional to the protein flexibility. The flexibility of cyt c was modulated by anions of Hofmeister series (sulfate, chloride, perchlorate) (Varhac et al. 2009). A minimalist scheme of the interaction of cyt c with hydrogen peroxide can be described by two steps: 1) interaction of hydrogen peroxide with heme iron forming the postulated ferryl intermediate, 2a) oxidation of another molecule of hydrogen peroxide and 2b) parallel oxidation of close amino acid residue(s) and/or heme. The catalase activity of cyt c is independent from the presence of Hofmeister anions, which indicates that both steps (1 and 2a) in the catalase reaction are independent from the flexibility of the heme region of the protein matrix. On the other hand, the flexibility of the polypeptide chain of the protein modulates the rate of parallel oxidative modification of the heme and amino acid residues.

Photodynamic effect of hypericin in primary cultures of human umbilical endothelial cells and glioma cell lines

Hypericin is the most powerful naturally occurring photosensitizer and as such there is renaissant interest in the potentials of this compound for anticancer photodynamic therapy (PDT). The purpose of this study was to investigate the hypericin-mediated photodynamic therapy effects on normal human umbilical endothelial cells (HUVECs) in comparison with cancer human glioma cell lines U-87 MG and U-373 MG, in in vitro conditions. The data suggest that endothelial cells as well as glioma cell lines are sensitive only to photoactivated hypericin. The inhibitory effects of photoactivated hypericin did not differ in endothelial compared with tumor cells in cytotoxicity MTT and DNA fragmentation assays. However, an important difference in sensitivity was found between the above mentioned cell types in migration and metalloproteinases inhibition assays performed as cell function tests. The findings in both function tests were supported by the high sensitivity of endothelial cells in an additional angiogenesis test of tubular formation in vitro.

In vitro antiproliferative and antiangiogenic effects of Flavin7

Flavin7 (F7) is a nutritional supplement often taken by cancer patients in Central Europe during chemo- and radiation therapy. In this study, investigation of the antiproliferative and antiangiogenic activities of this supplement were performed. Flavin7 showed antiproliferative activity in Jurkat as well as in HeLa cells. It significantly reduced the growth of both cancer cell lines at the doses of 200 microg/ml to 20 microg/ml (p<0.001 and p<0.01, respectively). In F7-treated Jurkat cells we found a significant increase in the fraction of cells with sub-G(0)/G(1) DNA content, which is considered to be a marker of apoptotic cell death. Apoptosis was also confirmed by annexin V staining and DNA fragmentation. Furthermore, F7 at the doses of 100 microg/ml to 4 microg/ml inhibited endothelial cell migration and capillary tube formation what indicates its potential antiangiogenic properties. Flavin7 also inhibited the activity of matrix metalloproteinases (MMPs), preferentially MMP-9, at the doses of 100 microg/ml to 4 microg/ml. Our data suggest that F7 possesses marked antiproliferative and antiangiogenic properties in vitro. Further research is needed to elucidate also its in vivo activities.