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At least 1,441 records · Page 80Linked to original sources
PubMed1999

Overexpression of protein kinase C-alpha in MCF-7 breast cancer cells results in differential regulation and expression of alphavbeta3 and alphavbeta5.

MCF-7 breast cancer cells stably transfected with protein kinase C-alpha (MCF-7-PKC-alpha cells) show anchorage-independent growth and exhibit increased tumorigenicity in nude mice. Since integrins are involved in tumor growth and metastatic spread, we investigated whether integrin expression is differentially regulated in MCF-7-PKC-alpha cells. Fluorescence-activated cell sorting revealed that alphavbeta3 is highly expressed on MCF-7-PKC-alpha cells, but is undetectable on MCF-7V cells (MCF-7 cells transfected with vector only). In contrast, MCF-7-PKC-alpha cells have reduced expression of alphavbeta5. Blocking experiments with antibodies to alphavbeta3 and alphavbeta5 revealed that these receptors are used by MCF-7-PKC-alpha cells to adhere primarily to vitronectin and osteopontin. Consistent with heterodimer expression, MCF-7-PKC-alpha cells express increased beta3 and decreased beta5 on their surface. Surface expression of alphav on MCF-7-PKC-alpha cells is unchanged. Western blotting, Northern analysis, and nuclear run-on assays indicated that post-translational mechanisms increase the surface expression of beta3 on MCF-7-PKC-alpha cells. In contrast, reduced beta5 transcription diminishes beta5 surface expression on MCF-7-PKC-alpha cells. These results indicate that overexpression of PKC-alpha in MCF-7 cells alters beta5 and beta3 expression by transcriptional and post-translational mechanisms, respectively, resulting in altered heterodimer expression. These findings suggest that the increased metastatic capacity of tumor cells with elevated protein kinase C levels may result, in part, from modulation of integrin expression.

Animals↗
PubMed1999

Prostatic carcinoma cell migration via alpha(v)beta3 integrin is modulated by a focal adhesion kinase pathway.

The highly invasive human prostate cancer PC3 cell line was found to express the alpha(v)beta3 integrin; in contrast, the noninvasive LNCaP prostate cancer cell line did not express alpha(v)beta3. PC3 cells adhered to and migrated on vitronectin (VN), an alpha(v)beta3 ligand expressed in mature bone where prostate cancer cells preferentially metastasize. In contrast, LNCaP cells did not adhere to or migrate on VN. Analysis of primary human prostate cancer cells isolated from 16 surgical specimens, showed that these cells expressed alpha(v)beta3, whereas normal prostate epithelial cells did not. In addition, only primary prostate cancer cells adhered to and migrated on VN. The role of alpha(v)beta3 in mediating prostate epithelial cell migration was confirmed using LNCaP cell transfectants expressing beta3 (beta3-LNCaP). Exogenous expression of alpha(v)beta3 induced LNCaP cells to adhere to and migrate on VN. In response to alpha(v)beta3 engagement, increased tyrosine phosphorylation of focal adhesion kinase (FAK), a signaling molecule activated by integrins and able to modulate cell migration, was detected. Transfection of FAK-related nonkinase, known to compete with FAK for its correct localization and phosphorylation, caused inhibition of beta3-LNCaP cell migration, specifically on VN. These data indicate that de novo expression of alpha(v)beta3 integrin in prostate cancer cells generates a migratory phenotype that is modulated by a FAK signaling pathway. This study points to alpha(v)beta3 as potential target in prostate cancer cell invasion and metastasis.

Cell Adhesion Molecules↗
PubMed1999

A novel disintegrin salmosin inhibits tumor angiogenesis.

Salmosin is a snake venom-derived novel disintegrin that antagonizes platelet aggregation. In this study, we investigated its functional specificity in tumor angiogenesis. Salmosin significantly inhibited bovine capillary endothelial cell proliferation induced by basic fibroblast growth factor but had no effect on normal growth of the cell. The basic fibroblast growth factor-induced in vivo angiogenesis in the chorioallantoic membrane was disrupted by salmosin treatment without affecting normal embryonic angiogenesis. Adhesion of the bovine capillary endothelial cells to vitronectin was also inhibited by the binding of salmosin to the alpha(v)beta3 integrin. Both the metastatic-tumor growth and the solid-tumor growth that developed in mice were effectively suppressed by salmosin treatment. Several lines of experimental evidence strongly suggest that the tumor-specific antiangiogenic activity of salmosin disrupts tumor growth by blocking the alpha(v)beta3 integrin that is expressed on the vascular endothelial cell surface.

Allantois↗
PubMed2000

Different mechanisms define the antiadhesive function of high molecular weight kininogen in integrin- and urokinase receptor-dependent interactions.

Proteolytic cleavage of single-chain high molecular weight kininogen (HK) by kallikrein releases the short-lived vasodilator bradykinin and leaves behind 2-chain high molecular weight kininogen (HKa) that has been previously reported to exert antiadhesive properties as well as to bind to the urokinase receptor (uPAR) on endothelial cells. In this study we defined the molecular mechanisms for the antiadhesive effects of HKa related to disruption of integrin- and uPAR-mediated cellular interactions. Vitronectin (VN) but not fibrinogen or fibronectin-dependent alphavbeta(3) integrin-mediated adhesion of endothelial cells was blocked by HKa or its isolated domain 5. In a purified system, HKa but not HK competed for the interaction of VN with alphavbeta(3) integrin, because HKa and the isolated domain 5 but not HK bound to both multimeric and native VN in a Zn(2+)-dependent manner. The interaction between HKa or domain 5 with VN was prevented by heparin, plasminogen activator inhibitor-1, and a recombinant glutathione-S-transferase (GST)-fusion peptide GST-VN (1-77) consisting of the amino terminal portion of VN (amino acids 1-77), but not by a cyclic arginyl-glycyl-aspartyl peptide, indicating that HKa interacts with the amino terminal portion of VN ("somatomedin B region"). Furthermore, we have confirmed that HKa but not HK bound to uPAR and to the truncated 2-domain form of uPAR lacking domain 1 in a Zn(2+)-dependent manner. Through these interactions, HKa or its recombinant His-Gly-Lys-rich domain 5 completely inhibited the uPAR-dependent adhesion of myelomonocytic U937 cells and uPAR-transfected BAF-3 cells to VN and thereby promoted cell detachment. By immunogold electron microscopy, both VN and HK/HKa were found to be colocalized in sections from human atherosclerotic coronary artery, indicating that the described interactions are likely to take place in vivo. Taken together, HK and HKa inhibit different VN-responsive adhesion receptor systems and may thereby influence endothelial cell- or leukocyte-related interactions in the vasculature, particularly under inflammatory conditions. (Blood. 2000;96:514-522)

Arteriosclerosis↗
PubMed2001

Inhibition of angiogenesis and tumor growth by SCH221153, a dual alpha(v)beta3 and alpha(v)beta5 integrin receptor antagonist.

New blood vessel formation is essential for tumor growth and metastatic spread. Integrins alpha(v)beta3 and alpha(v)beta5 are arginine-glycine-aspartic acid-dependent adhesion receptors that play a critical role in angiogenesis. Hence, selective dual alpha(v)beta3 and alpha(v)beta5 antagonists may represent a novel class of angiogenesis and tumor-growth inhibitors. Here, an arginine-glycine-aspartic acid-based peptidomimetic library was screened to identify alpha(v)beta3 antagonists. Selected compounds were then modified to generate potent and selective dual inhibitors of alpha(v)beta3 and alpha(v)beta5 receptors. One of these compounds, SCH 221153, inhibited the binding of echistatin to alpha(v)beta3 (IC50 = 3.2 nM) and alpha(v)beta5 (IC50 = 1.7 nM) with similar potency. Its IC50 values for related alpha(IIb)beta3 and alpha5beta1 receptors were 1294 nM and 421 nM, respectively, indicating that SCH 221153 is highly selective for alpha(v)beta3 and alpha(v)beta5 receptors. In cell-based assays, SCH 221153 inhibited the binding of echistatin to alpha(v)beta3- and alpha(v)beta5-expressing 293 cells and blocked the adhesion of endothelial cells to immobilized vitronectin and fibroblast growth factor 2 (FGF2). SCH 221153, but not the inactive analogue SCH 216687, was effective in inhibiting FGF2 and vascular endothelial growth factor-induced endothelial cell proliferation in vitro with an IC50 equal to 3-10 microM. Angiogenesis induced by FGF2 in the chick chorioallantoic membrane assay was also inhibited by SCH 221153. Finally, SCH 221153 exerted a significant inhibition on tumor growth induced by intradermal or s.c. injection of human melanoma LOX cells in severe combined immunodeficient mice.

Allantois↗
PubMed2001

Role of alphavbeta3 integrin receptors in breast tumor.

The intriguing problem of tumor metastasis involves adhesion of the metastatic cells via the integrin group of cell surface receptors to the ECM proteins of the basement membrane. Modulation of integrin family of cell surface receptors is believed to be associated with stages of tumor metastasis. In this present study, results obtained indicate that alphavbeta3 vitronectin receptors may play an important role in the malignant behaviour of human breast tumor. Alphavbeta3 integrin receptors can modulate the activity of collagenase enzyme and thereby the invasive property of breast tumor cells.

Breast Neoplasms↗
PubMed2002

Alpha(v)beta(3) integrin engagement enhances cell invasiveness in human multiple myeloma.

BACKGROUND AND OBJECTIVES: In multiple myeloma (MM), the mechanisms used by plasma cells to invade locally and metastasize are thought to be similar to those developed by solid tumors and include cell proliferation and secretion of extracellular matrix (ECM) degrading enzymes following adhesion to ECM proteins. We studied these mechanisms in fresh bone marrow plasma cells of patients with MM after adhesion to the ECM proteins vitronectin (VN) and fibronectin (FN). DESIGN AND METHODS: The ability of bone marrow plasma cells to adhere to VN and FN and the consequent formation of focal adhesion plaques on the cell surface, their composition and phosphorylation of several signal transduction proteins, cell proliferation and secretion of matrix metalloproteinase-2 (MMP-2) and -9 (MMP-9) and urokinase-type plasminogen activator (uPA) were studied. RESULTS: Plasma cells adhered to immobilized VN and FN. Adhesion was fully prevented by neutralizing anti-avb3 integrin antibody. Integrin engagement caused aggregation of the plaques, which contained the b3 integrin subunit, some cytoskeletal proteins, tyrosine kinases, the Grb-2 adapter protein, and mitogen-activated protein (MAP) kinase. Free and immobilized VN and FN stimulated cell proliferation and the production and the release of uPA, and increased the release of the activated forms of MMP-2 and MMP-9 in an avb3 integrin-dependent manner. INTERPRETATION AND CONCLUSIONS: This ability of myeloma plasma cells to interact with VN and FN via avb3 integrin engagement suggests a novel mechanism for their invasion and spreading, since this interaction allows them to adhere to the substratum and enhances their proliferation and protease secretion.

Adaptor Proteins, Signal Transducing↗
PubMedDate not supplied

The human platelet membrane glycoprotein IIb/IIIa complex: a multi functional adhesion receptor.

The glycoprotein GPIIb/IIIa complex is a major constituent of the platelet membrane; it plays an important role in platelet adhesion and aggregation. The complex is a member of the integrin superfamily. Integrins are related membrane receptors which mediate the adhesive interactions of a variety of cells; they specifically recognize the arginine-glycine-aspartic acid (RGD) sequence present in several adhesive proteins. The GPIIb/IIIa complex of activated platelets can bind fibrinogen, von Willebrand factor, fibronectin, vitronectin and thrombospondin. Platelets are activated by a variety of signals including extracellular matrix molecules and soluble factors; upon platelet activation the complex undergoes a conformational change, thus permitting the macromolecular ligands access to their binding sites. In turn, fibrinogen binding results in a receptor modification and neoantigens exposure; such events may participate in signal transduction. The adhesive proteins compete reciprocally for binding to GPIIb/IIIa, and the complex binds to different domains of them, thus creating multiple interactions with the ligands.

Amino Acid Sequence↗
PubMed2004

Doxorubicin-formaldehyde conjugates targeting alphavbeta3 integrin.

We have reported the synthesis and biological evaluation of a prodrug to a doxorubicin active metabolite. Under physiologic conditions, release of the active metabolite, a conjugate of doxorubicin with formaldehyde, occurs with a half-life of 1 hour. To direct this prodrug to tumor, we designed two conjugates of the prodrug, doxsaliform, with the alphavbeta3-targeting peptides, CDCRGDCFC (RGD-4C) and cyclic-(N-Me-VRGDf) (Cilengitide). We now report the synthesis of these doxsaliform-peptide conjugates and their evaluation using MDA-MB-435 cancer cells. A hydroxylamine ether tether was used to attach 5''-formyldoxsaliform to RGD-4C in its acyclic form via an oxime functional group. The construct acyclic-RGD-4C-doxsaliform showed good binding affinity for alphavbeta3 in the vitronection cell adhesion assay (IC50 = 10 nmol/L) and good growth inhibition of MDA-MB-435 breast cancer cells (IC50 = 50 nmol/L). In its bicyclic forms, RGD-4C showed less affinity for alphavbeta3 and significantly less water solubility. Cyclic-(N-Me-VRGDf) was modified by substitution of D-4-aminophenylalanine for D-phenylalanine to provide a novel attachment point for doxsaliform. The conjugate, cyclic-(N-Me-VRGDf-NH)-doxsaliform, maintained a high affinity for alphavbeta3 (IC50 = 5 nmol/L) in the vitronectin cell adhesion assay relative to the peptide bearing only the tether (0.5 nmol/L). The IC50 for growth inhibition of MDA-MB-435 cells was 90 nmol/L. Flow cytometry and growth inhibition experiments suggest that the complete drug construct does not penetrate through the plasma membrane, but the active metabolite does on release from the targeting group. These drug conjugates could have significantly reduced side effects and are promising candidates for in vivo evaluation in tumor-bearing mice.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1994

A beta turn in the cytoplasmic tail of the integrin alpha v subunit influences conformation and ligand binding of alpha v beta 3.

Integrins undergo conformational alterations in response to extracellular or intracellular stimuli, suggesting that structural elements within their exo- and cytoplasmic domains cooperate during transmembrane signaling. In this report, we identify a beta turn in the cytoplasmic tail of the alpha v subunit that impacts the ligand binding and conformation of the alpha v beta 3 heterodimer. Cells expressing a mutant alpha v beta 3 heterodimer composed of a truncated alpha v subunit, alpha v1000, lacking 18 carboxyl-terminal amino acids exhibits wild-type receptor structure and function. However, a truncation mutant, alpha v995, lacking five additional residues (PPQEE), which define a beta turn, is deficient in vitronectin and fibrinogen adhesion. This alteration in adhesive function is associated with two detectable structural changes in the alpha v beta 3 heterodimer. First, the alpha v995 membrane-spanning light chain exhibits retarded electrophoretic mobility on SDS-polyacrylamide gels. Second, the alpha v995 beta 3 receptor shows an altered chymotryptic profile as measured by the loss of a 39-kDa proteolytic fragment from its ectodomain. These findings demonstrate that the ligand binding and structural properties of the intact alpha v beta 3 heterodimer can be influenced by a beta turn within the cytoplasmic tail of its alpha v subunit. The presence of homologous beta turns within other alpha subunit cytoplasmic tails suggests that this structural motif may play a role in regulating integrin-mediated bidirectional transmembrane signals.

Amino Acid Sequence↗
PubMed1996

Transient functional expression of alphaVbeta 3 on vascular cells during wound repair.

During early granulation tissue formation of wound repair, new capillaries invade the fibrin clot, a process that undoubtedly requires an interaction of vascular cells with the wound provisional matrix composed mainly of fibrin, fibronectin, and vitronectin. Integrin alphaVbeta3 is the vascular cell receptor for these wound-associated adhesive proteins. Therefore, we investigated the expression of this receptor on new capillaries of healing full-thickness cutaneous porcine wounds. During granulation tissue formation, alphaVbeta3 was expressed specifically on capillary sprouts invading the central fibrin clot whereas the closely related integrin alphaVbeta5 failed to localize to these cells. Cyclic peptides or antibody antagonists of alphaVbeta3 specifically inhibited granulation tissue formation in a transient manner during the period of invasive angiogenesis. Immunolocalization studies revealed that alphaVbeta3 became aggregated and lost from sprouting vessels after treatment with a peptide antagonist. In contrast, beta 1 integrins were not modulated by this treatment. Once granulation tissue filled the wound and invasive angiogenesis terminated, the alphaVbeta3 showed little or no expression in the granulation tissue microvasculature. These data demonstrate that integrin alphaVbeta3 plays a fundamental, but transient, role during invasive angiogenesis and granulation tissue formation in a healing wound.

Analysis of Variance↗
PubMed1998

Heparin-binding domain of human fibronectin binds HIV-1 gp120/160 and reduces virus infectivity.

In vitro experiments indicate that components of the host present in body fluids may prevent the attachment of human immunodeficiency virus type 1 (HIV-1) to target cells. Fibronectin (Fn), a dimeric 440-kDa extracellular matrix adhesion protein, is secreted by mesenchymal cells and assembled into insoluble matrices. Fn exerts important effects on cell growth and differentiation through a number of discrete functional domains. Several microorganisms are known to bind Fn. We show that, under physiological conditions, HIV-1 gp120 and gp160 are capable of binding plasma and cellular Fn as well as laminin and vitronectin. Experiments were set up to analyze in detail the binding of HIV gp120 and gp160 to Fn. The gp120 and gp160 specifically recognize the C-terminal heparin-binding domain of Fn (Fn-CTHBD) with a calculated KD of 2.8 x 10(-7) M for gp160. Binding of gp160 to Fn-CTHBD is a saturable and specific process that is blocked by antibodies to Fn-CTHBD and by heparin and is inhibited to a minor extent by heparan sulfate and dextran sulfate. These observations suggest that gp120/160 specifically recognize the III15 repeat within Fn-CTHBD. Intact Fn and Fn-CTHBD strongly inhibit the interaction of gp120/160 with soluble CD4 and, under low serum conditions, are capable of neutralizing the infectivity of HIV-1 for CD4-positive T cells. Thus, Fn that is present in plasma and mucinous secretions may well affect HIV infectivity and virus distribution in vivo.

Antibodies↗
PubMed1999

Tenascin is differentially expressed in endometrium and endometriosis.

Endometriosis is characterized by the presence of functional endometrial tissue outside the uterine cavity, most commonly on the ovary and peritoneum. The aetiology of endometriosis is not understood, although the adhesion of endometrial cells to the extracellular matrix (ECM) would be expected to play a central role in its pathogenesis. The expression of ECM molecules in endometrium and in endometriosis has been investigated using immunohistochemistry and western blotting techniques. The ECM components collagen IV, laminin, vitronectin, and fibronectin had a similar pattern of expression throughout the menstrual cycle in endometrium and endometriosis. Expression of tenascin was elevated in the stroma of the functionalis region of the endometrium during the proliferative stage of the menstrual cycle and in endometriosis. Tenascin expression in endometriosis was not modulated according to the stage of the menstrual cycle. It is concluded that expression of tenascin is strictly regulated in endometrium and may be important in endometrial regeneration and in the pathogenesis of endometriosis.

Adult↗
PubMed2000

Follicular dendritic cells share a membrane-bound protein with fibroblasts.

The expression of a fibroblast antigen (AS02) on a proportion of CD21+ follicular dendritic cells (FDCs) provides evidence in support of their fibroblastic reticular origin. This antigen is expressed on the membrane of tissue fibroblasts but is absent from lymphocytes, macrophages or granulocytes. The distribution of AS02 in conjunction with other FDC markers (DRC-1, RFD3, CD23, IgM, and vitronectin) showed six types of FDCs. AS02 is present in the outer layers of primary and secondary follicles, but gradually decreases and disappears in the centre of germinal centres. In contrast, there is a progressive up-regulation of the other FDC markers. AS02 is re-expressed in involuting FDCs. Intermediate forms from fibroblastic to dendritic appearance are also apparent and occasionally FDC processes contain collagen type I and IV fibres, a characteristic feature of fibroblasts. In pathological follicles the normal differentiation pattern is disrupted, with persistence of the fibroblast marker, possibly due to altered interactions between FDCs and disrupted lymphocytic patterns. These findings provide new evidence for a local differentiation pathway of fibroblasts to mature FDCs.

Arthritis, Rheumatoid↗
PubMed2000

Functional activation of integrin alpha V beta 3 in tumor cells expressing membrane-type 1 matrix metalloproteinase.

Matrix metalloproteinases (MMPs) and integrins have been implicated in a variety of processes involved in tumor progression. To evaluate the individual roles of integrin alphavbeta3 and membrane-type 1 matrix metalloproteinase (MT1-MMP), as well as the effects of their joint expression on tumor cell functions, MCF7 breast carcinoma cells were transfected stably with either the MT1-MMP, the beta3 integrin subunit or both MT1-MMP and beta3 cDNAs. MT1-MMP expression is accompanied by the functional activation of integrin alphaVbeta3, thereby increasing vitronectin-mediated adhesion and migration of MCF7 cells transfected with MT1-MMP and integrin alphaVbeta3. MT1-MMP-dependent functional activation of alphaVbeta3 correlates with modification(s) of the beta3 subunit, including its higher electrophoretic mobility and affected the LM609-binding site. MCF7 cells jointly expressing MT1-MMP and alphaVbeta3 were the most efficient in adhesion to the recombinant C-terminal domain of MMP-2 as well as in generating soluble and cell surface associated mature MMP-2 enzyme. These findings suggest a mechanism of selective docking of MMP-2 at tumor cell surfaces, specifically at the sites that include MT1-MMP and activated integrin alphaVbeta3. These mechanisms may provide a link between spatial regulation of focal proteolysis by the cell surface associated MMPs and the regulation of integrin-mediated motility of tumor cells.

Antigens, CD↗
PubMed1997

Localization of plasminogen activators and their inhibitor in squamous cell carcinomas of the head and neck.

BACKGROUND: Plasminogen activators (PAs) and their inhibitors are thought to play an important role in tumor invasion and metastasis. However, there have been few reports in which histologic localization of PAs has been demonstrated in head and neck tumors. METHODS: We examined the patterns of expression of urokinase-type plasminogen activator (u-PA), tissue-type plasminogen activator (t-PA), plasminogen activator inhibitor 1 (PAI-1), and vitronectin in head and neck squamous cell carcinomas using immunohistochemical techniques. We also studied the correlation between the immunohistologic expression of these fibrinolytic proteins and the clinical staging of the tumor. RESULTS: Of 28 tumor specimens, 15 (54%) showed immunoreactivity for u-PA; 8 (36%), for t-PA; and 23 ( 82%), for PAI-1. There was a significant correlation between PAI-1 expression and the extent of the primary tumor. CONCLUSIONS: The present study demonstrates the existence and possible pathophysiologic significance of u-PA and PAI-1 in squamous cell carcinomas of the head and neck.

Carcinoma, Squamous Cell↗
PubMed2000

Adsorbed serum proteins responsible for surface dependent human macrophage behavior.

Substrate specific cellular responses are the result of a complex biological system that includes protein adsorption, receptor-ligand binding, and signal transduction. This investigation attempted to identify specific proteins adsorbed from human serum that may be responsible for the previously reported in vitro surface dependent behavior of human macrophages and foreign body giant cells (FBGCs). The adsorption of human albumin, alpha(2)-macroglobulin, complement factor 3b, fibronectin, IgG, thrombospondin, vitronectin (VN), and von Willebrand factor (vWF) from a 25% serum solution was quantified with (125)I-labeled protein. Adsorption substrates included clean glass, alkyl-silane modified glass, amino-silane modified glass, poly(ethylene oxide) (PEO)-coupled glass, and the reference biomaterials poly(etherurethane urea), Silastic(R), and poly(tetrafluoroethylene) (PTFE). Following quantification of 2-h adsorption, surfaces were treated with sodium dodecyl sulfate (SDS) and the level of adsorbed proteins remaining was quantified. The pre- and post-SDS adsorption were both compared to previously reported surface dependent in vitro macrophage and FBGC behavior on the same surfaces; however, no correlations could be made. Adsorption strength, defined as the percentage of initially adsorbed protein that remained adsorbed after SDS treatment, correlated well with previously reported in vitro cellular behavior indicating that adsorbed vWF, IgG, and VN may be involved in the modulation of adherent macrophage and FBGC behavior. Those surfaces that strongly adsorbed vWF also inhibited long-term macrophage adhesion, while those surfaces that strongly adsorbed IgG promoted long-term macrophage adhesion. In addition, the highest levels of FBGC formation had been observed only on those surfaces that strongly adsorbed VN. Subsequent human monocyte cultures on protein preadsorbed substrates confirmed the inhibitory effect of adsorbed vWF and the promoting effect of IgG on longterm macrophage adhesion as predicted by adsorption strength correlations. However, preadsorbed VN was not observed to modulate FBGC formation, which is in contrast to the conclusions of the adsorption correlations.

Adsorption↗
PubMed1999

Osteoclast markers accumulate on cells developing from human peripheral blood mononuclear precursors.

Recent studies show that human osteoclasts develop in vitro from hematopoietic cells; however, special cultures conditions and/or cytokine mobilized peripheral blood are apparently required. Here, we report that cells expressing osteoclast markers differentiate from precursors present in nonmobilized peripheral blood mononuclear cells (PBMC), without the addition of stromal cells, growth factors, cytokines or steroids; and characterize their phenotype. Three days after establishing high-density PBMC cultures (1.5 x 10(6) cells/cm2), in serum-containing medium, small adherent colonies of tartrate resistant acid phosphatase positive (TRAP+) cells emerge, amidst massive monocyte cell death. These adherent cells have an eccentrically placed, round nucleus, and express low levels of TRAP and sodium fluoride-resistant- alpha-naphthyl-acetate-esterase (NaF-R-NSE). Over the next week, this cell population accumulates phenotypic markers of osteoclasts (vitronectin receptor [VR], calcitonin receptor, TRAP, cathepsin K protein, and mRNA) with increased nuclearity, covering the entire surface by 15 days. When cultured on bone, VR+, TRAP+ cells of low multinuclearity appear and cover up to 50% of the surface. Resorption lacunae can be observed by day 22. Although these pits are not nearly as numerous as the cells of preosteoclast phenotype, they do represent the activity of a subset of osteoclast-like cells that has achieved osteoclastic maturity under these culture conditions. Transcripts for osteoprotegerin ligand (OPGL), an osteoclast differentiation factor (also known as RANKL and TRANCE) are expressed, likely by adherent cells. Thus, an adherent population of cells, with preosteoclast/osteoclast phenotypic properties, arises selectively under simple culture conditions from normal PBMC. Further characterization of these cells should identify factors involved in the growth, terminal differentiation and activation of osteoclasts.

Acid Phosphatase↗