Thymosin β4 Promotes Dermal Healing

No agent has been identified that significantly accelerates the repair of chronic dermal wounds in humans. Thymosin beta 4 (Tβ4) is a small, abundant, naturally occurring regenerative protein that is found in body fluids and inside cells. It was found to have angiogenic and antiinflammatory activity and to be high in platelets that aggregate at the wound site. Thus we used Tβ4 initially in dermal healing. It has since been shown to have many activities important in tissue protection, repair, and regeneration. Tβ4 increases the rate of dermal healing in various preclinical animal models, including diabetic and aged animals, and is active for burns as well. Tβ4 also accelerated the rate of repair in phase 2 trials with patients having pressure ulcers, stasis ulcers, and epidermolysis bullosa wounds. It is safe and well tolerated and will likely have additional uses in the skin and in injured organs for tissue repair and regeneration.

Effects of amelogenins on angiogenesis-associated processes of endothelial cells

OBJECTIVE

To study the effects of an amelogenin mixture on integrin-dependent adhesion, DNA synthesis and apoptosis of cultured human dermal microvascular endothelial cells and angiogenesis in an organotypic assay.

METHOD

Immobilised antibodies against specific integrins (alpha-1, alpha-2, alpha-3, alpha-4, alpha-5, alpha-v, ß1, ß2, ß3, ß4, ß6, alpha-vß3, alpha-vß5 and alpha-5ß1) were used to capture treated human dermal microvascular endothelial cells, which were detected colourimetrically. DNA synthesis of the cells was monitored by 5-bromo-2'- deoxyuridine incorporation and apoptosis by a TdT-mediated dUTP nick-end labelling technique. Tubule formation from aortic arches of 13-d-old chick embryos were followed over 48h.

RESULTS

The amelogenin mixture increased microvessel outgrowth by 76% (p < 0.01, n=12) from the aortic explants. Also, amelogenins increased the adhesion (p < 0.01, n = 5) by multiple angiogenesis associated integrin subunits and alpha-vß3, alpha-vß5 and alpha-5ß1 heterodimers on human dermal microvascular endothelial cells at a non-mitogenic concentration (100 µg/ml). Conversely, amelogenins at 1,000 µg/ml decreased microvessel formation possibly due to attenuation of corresponding integrins despite increasing (p < 0.001, n = 8) DNA synthesis. No significant apoptosis was detected in human dermal microvascular endothelial cells cultured on Matrigel with and without amelogenins.

CONCLUSION

Increased surface expression of integrins on endothelial cells may contribute to the proangiogenic property of amelogenins.

The regulation of basement membrane formation and cell-matrix interactions by defined supramolecular complexes

Several constituents of basement membranes, including type IV collagen, laminin, heparan sulphate proteoglycan and nidogen, form a defined supramolecular complex that is an obligatory intermediate in the formation of this matrix. We have named this defined supramolecular complex the 'basement membrane matrisome'. Matrisome structures composed of other collagens, proteoglycans and glycoproteins may participate in the formation of other extracellular matrices. Cells show specific interactions with components of the extracellular matrix. We discuss studies that indicate that melanoma cells can express receptors for both laminin and fibronectin. However, these receptors are expressed in a reciprocal fashion, depending on the exposure of the cell to these proteins. Binding of either fibronectin or laminin to the cells elicits a distinct phenotype. This represents a mechanism in which cellular activity can be regulated by extracellular matrix factors during development and in repair.

Invasion assays

Basement membrane is a thin extracellular matrix that underlies epithelia and endothelia and separates them from the stroma. Tumor cells must cross this membrane to invade stroma and establish distant metastases. They do this by producing proteases that degrade the matrix. Of several in vitro models, those using Matrigel are the most reliable, reproducible, and representative of in vivo invasion. In the assay presented here, tumor cells are placed in the upper chamber of Boyden migration chamber. The upper and lower chambers are separated by a porous membrane coated with Matrigel. A chemoattractant in the lower well stimulates migration. After an interval, tumor cells are recovered from or counted on the lower surface of the membrane.

Preparation of basement membrane components from EHS tumors

This unit describes methods for passaging and harvesting the basement membrane matrix-producing EHS tumor and for the subsequent isolation of a crude mixture of basement membrane components termed Matrigel, which promotes the differentiation of a variety of epithelial, endothelial, and neuronal cells. Procedures for the isolation of the adhesive glycoprotein laminin-1 and of type IV collagen are also included. Support protocols cover the maintenance and harvesting of EHS tumors in mice and maintenance of mice on a lathrogenic diet.

Preparation of gelled substrates

Gelled substrates can be used for a variety of in vitro and in vivo experiments. A type I collagen gelled substrate will promote cell growth and differentiation. Gelled Matrigel substrate promotes the survival of explanted cells and tissues and the differentiation of a variety of epithelial and endothelial cell types in vitro and to assess angiogenesis and increase tumor growth in vivo. Preparation of the matrices and their use are described in this unit.

C16 laminin peptide increases angiotropic extravascular migration of human melanoma cells in a shell-less chick chorioallantoic membrane assay

BACKGROUND

As distinct from intravascular dissemination, extravascular migratory metastasis (EVMM) has been described as a potential additional mechanism of melanoma spread in which tumour cells migrate along the external surfaces of vessels. Recent experimental studies strongly suggest a correlation of angiotropism of melanoma cells with EVMM. Angiotropic melanoma cells are linked to the endothelium by an amorphous matrix confirmed to contain laminin.

OBJECTIVES

To investigate whether laminin plays a role in this extravascular mechanism of tumour spread.

METHODS

We tested the effect of the C16 laminin peptide on melanoma spread in a shell-less chick chorioallantoic membrane model.

RESULTS

After 3 days, green fluorescent protein-expressing melanoma cells were observed spreading along or in the immediate proximity of vessels. The C16 laminin peptide significantly lengthened the distance of extravascular, angiotropic migration of melanoma cells. Histopathology confirmed the angiotropism of melanoma cells without intravasation, compatible with that observed with human angiotropic melanoma.

CONCLUSIONS

The results of this study suggest that the C16 laminin gamma1 chain peptide has angiotropic, extravascular migration-promoting activity on human melanoma cells, and might be a molecular target for preventing melanoma metastasis.

Amelogenin-mediated regulation of osteoclastogenesis, and periodontal cell proliferation and migration

We previously reported that amelogenin isoforms M180 and leucine-rich amelogenin peptide (LRAP) are expressed in the periodontal region, and that their absence is associated with increased cementum defects in amelogenin-knockout (KO) mice. The aim of the present study was to characterize the functions of these isoforms in osteoclastogenesis and in the proliferation and migration of cementoblast/periodontal ligament cells. The co-cultures of wild-type (WT) osteoclast progenitor and KO cementoblast/periodontal ligament cells displayed more tartrate-resistant acid phosphatase (TRAP)-positive cells than the co-cultures of WT cells. The addition of LRAP to both co-cultures significantly reduced RANKL expression and the TRAP-positive cells. Proliferation and migration rates of the KO cementoblast/periodontal ligament cells were lower than those of WT cells and increased with the addition of either LRAP or P172 (a porcine homolog of mouse M180). Thus, we demonstrate the regulation of osteoclastogenesis by LRAP, and the proliferation and migration of cementoblast/periodontal ligament cells by LRAP and P172.

Association between increased CCL2 (MCP-1) expression in lesions and persistence of disease activity in giant-cell arteritis*

OBJECTIVE

Patients with giant-cell arteritis (GCA) usually respond dramatically to corticosteroid treatment. However, recurrences are frequent and corticosteroid requirements are highly variable among patients. The aim of our study was to identify genes potentially involved in disease persistence.

METHODS

Gene expression was explored with cDNA arrays in temporal artery biopsies from six GCA patients with relapsing disease and six patients who easily achieved sustained remission. Differentially expressed genes of interest were subsequently analysed by quantitative real-time polymerase chain reaction (PCR) and immunohistochemistry in temporal artery biopsies from 35 patients with biopsy-proven GCA and nine controls.

RESULTS

CCL2 (MCP-1) was up-regulated in temporal artery samples from relapsing individuals. In the extended series of patients, CCL2 mRNA concentration in lesions was significantly higher than in controls (31 +/- 15.6 vs 0.44 +/- 0.10, P = 0.0001). In addition, CCL2 was more abundant in patients who experienced two or more relapses during the first year compared with those who endured sustained remission (127 +/- 82 vs 11 +/- 5.5, P = 0.0233) and correlated with the cumulated prednisolone dose (R = 0.533, P = 0.0024). CCL2 mRNA concentration correlated with IL-1beta (R = 0.45, P = 0.02), tumour necrosis factor-alpha (TNF-alpha) (R = 0.47, P = 0.013) and IL-6 (R = 0.52, P = 0.0053) mRNA. However, circulating CCL2 determined by ELISA was decreased in patients with strong systemic inflammatory response, suggesting that reduction in circulating CCL2 may reinforce the local gradient in lesions.

CONCLUSION

Increased CCL2 (MCP-1) expression in lesions is associated with persistence of disease activity in GCA.

Thymosin beta4 promotes angiogenesis, wound healing, and hair follicle development

New blood vessel formation is important in many physiological process, including development, wound repair, and tumor growth. In aged animals, angiogenesis is reduced resulting in poor wound healing. We have identified a novel small molecule, thymosin beta(4), that promotes angiogenesis and wound repair in both normal and aged rodents. It also promotes hair growth in normal and aged rodents. It acts by increasing angiogenesis and cell migration and is currently in clinical trials for wound repair.

Estradiol enhances endothelial cell interactions with extracellular matrix proteins via an increase in integrin expression and function

Premenopausal women have a lower cardiovascular risk and a higher incidence of several autoimmune diseases involving blood vessels than men. Although the precise effects of estrogens on the cardiovascular system are largely unknown, recent data suggest that estrogens can exert direct regulatory effects on endothelial cells. In the present study, we show that 17beta-estradiol increases human umbilical vein endothelial cell attachment to the extracellular matrix proteins laminin-1, type IV collagen, type I collagen, and fibronectin. Estradiol enhanced adhesion most significantly to laminin-1 and to fibronectin-derived synthetic peptides containing an RGD sequence. Upon exposure to estradiol, an increase in beta1, alpha5 and alpha6 integrin mRNA was observed in subconfluent cells which was abrogated by treatment with cycloheximide. This increase was followed by a later enhancement in surface expression of the above integrins. In addition, integrin-mediated signaling was also enhanced by estrogens since an increase in tyrosine-phosphorylation of focal adhesion kinase induced by cell attachment was observed in estrogen-treated endothelial cells. Since integrins have an important role in mediating endothelial cell attachment, migration and differentiation, the increase in integrin expression and function induced by estradiol may be an important mechanism through which estrogens can promote neovascularization and vessel repair.

NOVH increases MMP3 expression and cell migration in glioblastoma cells via a PDGFR-alpha-dependent mechanism

Nephroblastoma overexpressed gene (NOV) is highly expressed in the nervous system. We investigated its biological activity by expressing the human NOV gene (NOVH) in a human glioblastoma cell line that is negative for NOVH and by analyzing four clones with different levels of NOVH expression. There was no difference in cell proliferation between the NOVH-expressing cell lines, but there was increased cell adhesion and migration that correlated with increasing NOVH expression. Gene expression profiling was used to investigate the mechanisms by which NOVH expression regulated cell activity. We identified two induced genes in NOVH-expressing cells that are involved in cell migration: matrix metalloprotease (MMP)3 and platelet-derived growth factor receptor (PDGFR)-alpha. Our studies show that PDGFR-alpha induced MMP3 gene expression and increased cell proliferation and cell migration upon stimulation by platelet-derived growth factor (PDGF)-AA. We also show that the induction of MMP3 in cells expressing NOVH is potentiated by either cell density, serum, or PDGF-BB. Thus, expression of NOVH in glioblastoma cells triggers a cascade of gene expression resulting in increased cell adhesion and migration.

Biological response of chondrocytes to hydrogels

Primary bovine chondrocytes were encapsulated in alginate and alginate combined with cartilage matrix extract, Cartrigel, for the purpose of cartilage tissue engineering. The cell constructs were incubated in vitro and gene expression of cartilage-specific extracellular matrix molecules was quantitated and localized with in situ hybridization with a decrease in expression observed in the alginate-Cartrigel constructs. Further understanding of cell response to scaffolds will allow rational design and development of hydrogels for cartilage tissue engineering.

Laminin gamma 1 chain peptide, C-16 (KAFDITYVRLKF), promotes migration, MMP-9 secretion, and pulmonary metastasis of B16-F10 mouse melanoma cells

Laminin-1, a heterotrimer of alpha 1, beta 1, and gamma 1 chains specific to basement membrane, promotes cell adhesion and migration, proteinase secretion and metastases of tumour cells. Several active sites on the alpha 1 chain have been found to promote B16-F10 melanoma lung colonisation and here we have determined whether additional tumour promoting sites exist on the beta 1 and gamma 1 chains. Recently, we have identified novel cell adhesive peptides derived from laminin beta 1 and gamma 1 chains by systematic screening of synthetic peptides. Nine beta 1 peptides and seven gamma 1 peptides active for cell adhesion were tested for their effects on experimental pulmonary metastases of B16-F10 mouse melanoma cells in vivo. The most active adhesive peptide derived from the gamma 1 chain globular domain, C-16 (KAFDITYVRLKF), significantly enhanced pulmonary metastases of B16-F10 cells, whereas no other peptides showed enhancement. C-16 also stimulated migration of B16-F10 cells in the Boyden chamber assay in vitro. Furthermore, C-16 significantly induced the production of MMP-9 from B16-F10 cells. These results suggest that this specific laminin gamma 1 chain peptide has a metastasis-promoting activity and might be a new molecular target of anti-cancer treatment.

Identification of homologous biologically active sites on the N-terminal domain of laminin alpha chains

Laminin, a multifunctional glycoprotein of the basement membrane, consists of three different subunits, alpha, beta, and gamma chains. To date, five different alpha chains have been identified. N-terminal domain VI in the alpha1 chain has various biological activities. Here we screened biologically active sequences on domain VI of the laminin alpha2, alpha3, and alpha5 chains using a large number of overlapping peptides. HT-1080 human fibrosarcoma cell attachment to the peptides was evaluated using peptide-coated plastic plates and peptide-conjugated Sepharose beads. We identified four cell adhesive sequences from laminin alpha2 chain domain VI, two sequences from the alpha3 chain, and two sequences from the laminin alpha5 chain. Sequences homologous to A13 (RQVFQVAYIIIKA, alpha1 chain 121-133) on all the alpha chains (FQIAYVIVKA, alpha2 chain 130-139; GQLFHVAYILIKF, alpha3 chain 96-108; FHVAYVLIKA, alpha5 chain 74-83) showed strong cell attachment activity. A5-16 (LENGEIVVSLVNGR, alpha5 chain 147-160) showed the strongest cell attachment activity in the plate assay, and the homologous peptide in the alpha3 chain promoted similar strong cell attachment activity. A5-16 and its homologous peptide in the alpha2 chain promoted moderate cell attachment, while the homologous peptide to A5-16 in the alpha1 chain did not show activity. A2-7 (SPSIKNGVEYHYV, alpha2 chain 108-120) showed cell attachment activity only in the plate assay, but homologous sequences in the alpha1, alpha3, and alpha5 chains did not promote activity. A2-7 promoted endothelial cell sprouting from aortic rings in vitro and melanoma colonization to murine lungs in vivo. However, none of the homologous peptides of A2-7 promoted experimental pulmonary metastasis by B16-BL6 melanoma cells. These results indicate that there are chain-specific active sites in domain VI of the laminin alpha chains, some of which contain conserved activities.

The influence of extracellular matrix on the generation of vascularized, engineered, transplantable tissue

In a recently described model for tissue engineering, an arteriovenous loop comprising the femoral artery and vein with interposed vein graft is fabricated in the groin of an adult male rat, placed inside a polycarbonate chamber, and incubated subcutaneously. New vascularized granulation tissue will generate on this loop for up to 12 weeks. In the study described in this paper three different extracellular matrices were investigated for their ability to accelerate the amount of tissue generated compared with a no-matrix control. Poly-D,L-lactic-co-glycolic acid (PLGA) produced the maximal weight of new tissue and vascularization and this peaked at two weeks, but regressed by four weeks. Matrigel was next best. It peaked at four weeks but by eight weeks it also had regressed. Fibrin (20 and 80 mg/ml), by contrast, did not integrate with the generating vascularized tissue and produced less weight and volume of tissue than controls without matrix. The limiting factors to growth appear to be the chamber size and the capacity of the neotissue to integrate with the matrix. Once the sides of the chamber are reached or tissue fails to integrate, encapsulation and regression follow. The intrinsic position of the blood supply within the neotissue has many advantages for tissue and organ engineering, such as ability to seed the construct with stem cells and microsurgically transfer new tissue to another site within the individual. In conclusion, this study has found that PLGA and Matrigel are the best matrices for the rapid growth of new vascularized tissue suitable for replantation or transplantation.

Evaluation of the chemopreventive potential of retinoids using a novel in vitro human prostate carcinogenesis model

The prevalence of prostatic intraepithelial neoplasia (PIN) and latent prostatic carcinoma, representing multiple steps in carcinogenesis and progression to invasive carcinoma, makes them relevant targets for prevention. A unique family of human prostate epithelial cell lines, which mimic steps in prostate carcinogenesis and progression, were used to evaluate the chemopreventive potential of all-trans-retinoic acid (RA) and N-(4-hydroxyphenyl)retinamide (4-HPR). The effects of RA and 4-HPR on anchorage-dependent growth of an immortalized, non-tumorigenic cell line RWPE-1 and two tumorigenic cell lines, WPE1-NB14 and WPE1-NB11, derived from RWPE-1 by exposure to N-methyl-N-nitrosourea (MNU), were examined. Both tumorigenic cell lines grow more rapidly than the parent RWPE-1 cell line in monolayer culture. Further, while RWPE-1 cells do not form colonies in agar, both tumorigenic cell lines do, with a colony forming efficiency (CFE) of 1.85 and 2.04% for WPE1-NB14 and WPE1-NB11 cells, respectively. Both RA and 4-HPR inhibited anchorage-dependent growth of all cell lines and anchorage-independent growth of WPE1-NB14 and WPE1-NB11 cells, in a dose-dependent manner, however, 10 times more RA than 4-HPR was required to produce the same effect. RWPE-1 cells are not invasive but WPE1-NB11 cells are significantly more invasive than WPE1-NB14 cells. Both RA and 4-HPR inhibited invasion in vitro by WPE1-NB11 and WPE1-NB14 cells where the more malignant WPE1-NB11 cells showed greater inhibition of invasion by 4-HPR than by RA. Overall, 4-HPR was more effective than RA in inhibiting growth and invasion but the response varied amongst the cell lines. These three cell lines mimic progressive steps in carcinogenesis and progression, from immortalized, non-tumorigenic RWPE-1 cells, to the less malignant WPE1-NB14 to the more malignant WPE1-NB11 cells, and provide powerful models for studies on secondary and tertiary prevention, i.e. promotion and progression stages, respectively, of prostate cancer.

The role of alpha 6 beta 1 integrin and EGF in normal and malignant acinar morphogenesis of human prostatic epithelial cells

Complex multiple interactions between cells and extracellular matrix occur during acinar morphogenesis involving integrin receptors and growth factors. Changes in these interactions occur during carcinogenesis as cells progress from a normal to a malignant, invasive phenotype. We have developed human prostatic epithelial cell lines of the same lineage, which represent multiple steps in carcinogenesis, similar to prostatic intraepithelial neoplasia and subsequent tumor progression. The non-tumorigenic, RWPE-1 and the tumorigenic WPE1-NB27 and WPE1-NB26 cell lines were used to examine their ability to undergo acinar morphogenesis in a 3-D cell culture model and its relationship to invasion, integrin expression and EGF presence. An inverse relationship between the degree of acinar formation and invasive ability was observed. The non-tumorigenic, non-invasive RWPE-1 and the low tumorigenic, low invasive, WPE1-NB27 cells show high and decreased acinar forming ability, respectively, while the more invasive WPE1-NB26 cells show a loss of acinar formation. While RWPE-1 acini show basal expression of alpha 6 beta 1 integrin, which correlates with their ability to polarize and form acini, WPE1-NB27 cells lack alpha 6 but show basal, but weaker expression of beta 1 integrin. WPE1-NB26 cells show loss alpha 6 and abnormal, diffused beta 1 integrin expression. A dose-dependent decrease in acinar formation was observed in RWPE-1 cells when cell proliferation was induced by EGF. Anti-functional antibody to EGF caused an increase in acinar formation in RWPE-1 cells. These results suggest that malignant cells lose the ability to undergo acinar morphogenesis and that the degree of this loss appears to be related to invasive ability, EGF levels and alterations in laminin-specific integrin expression. This model system mimics different steps in prostate carcinogenesis and has applications in the secondary and tertiary prevention of prostate cancer.

Cell type-specific differences in glycosaminoglycans modulate the biological activity of a heparin-binding peptide (RKRLQVQLSIRT) from the G domain of the laminin alpha1 chain

AG73 (RKRLQVQLSIRT), a peptide from the G domain of the laminin alpha1 chain, has diverse biological activities with different cell types. The heparan sulfate side chains of syndecan-1 on human salivary gland cells were previously identified as the cell surface ligand for AG73. We used homologous peptides from the other laminin alpha-chains (A2G73-A5G73) to determine whether the bioactivity of the AG73 sequence is conserved. Human salivary gland cells and a mouse melanoma cell line (B16F10) both bind to the peptides, but cell attachment was inhibited by glycosaminoglycans, modified heparin, and sized heparin fragments in a cell type-specific manner. In other assays, AG73, but not the homologous peptides, inhibited branching morphogenesis of salivary glands and B16F10 network formation on Matrigel. We identified residues critical for AG73 bioactivity using peptides with amino acid substitutions and truncations. Fewer residues were critical for inhibiting branching morphogenesis (XKXLXVXXXIRT) than those required to inhibit B16F10 network formation on Matrigel (N-terminal XXRLQVQLSIRT). In addition, surface plasmon resonance analysis identified the C-terminal IRT of the sequence to be important for heparin binding. Structure-based sequence alignment predicts AG73 in a beta-sheet with the N-terminal K (Lys(2)) and the C-terminal R (Arg(10)) on the surface of the G domain. In conclusion, we have determined that differences in cell surface glycosaminoglycans and differences in the amino acids in AG73 recognized by cells modulate the biological activity of the peptide and provide a mechanism to explain its cell-specific activities.

Eotaxin (CCL11) induces in vivo angiogenic responses by human CCR3+ endothelial cells

Chemokines are attractants and regulators of cell activation. Several CXC family chemokine members induce angiogenesis and promote tumor growth. In contrast, the only CC chemokine, reported to play a direct role in angiogenesis is monocyte-chemotactic protein-1. Here we report that another CC chemokine, eotaxin (also known as CCL11), also induced chemotaxis of human microvascular endothelial cells. CCL11-induced chemotactic responses were comparable with those induced by monocyte-chemotactic protein-1 (CCL2), but lower than those induced by stroma-derived factor-1alpha (CXCL12) and IL-8 (CXCL8). The chemotactic activity was consistent with the expression of CCR3, the receptor for CCL11, on human microvascular endothelial cells and was inhibited by mAbs to either human CCL11 or human CCR3. CCL11 also induced the formation of blood vessels in vivo as assessed by the chick chorioallantoic membrane and Matrigel plug assays. The angiogenic response induced by CCL11 was about one-half of that induced by basic fibroblast factor, and it was accompanied by an inflammatory infiltrate, which consisted predominantly of eosinophils. Because the rat aortic sprouting assay, which is not infiltrated by eosinophils, yielded a positive response to CCL11, this angiogenic response appears to be direct and is not mediated by eosinophil products. This suggests that CCL11 may contribute to angiogenesis in conditions characterized by increased CCL11 production and eosinophil infiltration such as Hodgkin's lymphoma, nasal polyposis, endometriosis, and allergic diathesis.

An angiogenic laminin site and its antagonist bind through the alpha(v)beta3 and alpha5beta1 integrins

Angiogenesis is important for wound healing, tumor growth, and metastasis. Endothelial cells differentiate into capillary-like structures on a laminin-1-rich matrix (Matrigel). We previously identified 20 angiogenic sites on laminin-1 (alpha1beta1gamma1) by screening 559 overlapping synthetic peptides. C16, the most potent gamma1 chain peptide, blocked laminin-1-mediated adhesion and was the only gamma1 chain peptide to block attachment to both collagen I and fibronectin. This suggested that C16 was acting via a receptor common to these substrates. We demonstrated that C16 is angiogenic in vivo. Affinity chromatography identified the integrins alpha5beta1 and alpha(v)beta3 as surface receptors. Blocking antibodies confirmed the role of these receptors in C16 adhesion. C16 does not contain an RGD sequence and, as expected, an RGD-containing peptide did not block C16 adhesion nor did C16 act via MAP kinase phosphorylation. Furthermore, we identified a C16 scrambled sequence, C16S, which antagonizes the angiogenic activity of bFGF and of C16 by binding to the same receptors. Because the laminin gamma1 chain is ubiquitous in most tissues, C16 is likely an important functional site. Since the biological activity of C16 is blocked by a scrambled peptide, C16S may serve as an anti-angiogenic therapeutic agent.

Stimulation of tumor growth by human soluble intercellular adhesion molecule-1

Because serum levels of soluble intercellular adhesion molecule-1 (sICAM-1) are elevated in cancer and sICAM-1 is angiogenic, we tested the ability of sICAM-1 to promote tumor growth. Our preliminary experiments showed that exogenous sICAM-1 significantly stimulated the growth of human tumors in vivo. Human fibrosarcoma transfectants, which express ICAM-1, produce ICAM-1 on the cell surface and release sICAM-1 into the medium without any apparent effect on cell growth in vitro. We found that conditioned medium from sense ICAM-1 transfectants compared with mock or antisense ICAM-1 transfectants stimulates endothelial cell migration in vitro and neovascularization in the chick chorioallantoic membrane assay. Tumor cells transfected with sense constructs form faster growing tumors than mock- and antisense-transfected cells in both chick embryos and nude mice models. Serum levels of human sICAM-1 from nude mice bearing sense ICAM-1 transfectants correlate positively with tumor weight. Sense ICAM-1 transfectants are more proliferative and induce more blood vessel formation than mock and antisense transfectants in nude mice. Because expression of ICAM-1 does not affect tumor cell growth in vitro, the angiogenic activity of sICAM-1 produced by sense ICAM-1 transfectants may be involved in the stimulation of tumor growth. Therefore, sICAM-1 may perform dual functions that are essential for tumor growth: angiogenesis and escape from immune surveillance.

Role of laminin in ovarian cancer tumor growth and metastasis via regulation of Mdm2 and Bcl-2 expression

Ovarian cancer is among the most lethal cancers in women because of its high metastatic potential and lack of response to therapy. An experimental model to study this disease was developed using a transformed granulosa cell line expressing a mutant p53 and Ha-ras. When injected into the ovary of nude mice in the presence of laminin-1, tumors develop in the ovary and peritoneum and metastasize to various organs, leading to death within 21 days. In contrast, when cells were injected in the presence of gelatin, development of tumors was slower and no metastases were observed by day 21. Here we investigated the possible mechanism by which laminin-1 exerts its promotion of tumorigenesis and metastasis. Cells were co-injected with laminin-1 and active laminin peptides from the alpha1; (A13: RQVFQVAYIIIKA, A12: WVTVTLDL RQVFQ, AG73: LQVQLSIR, IKVAV) and beta1 (YIGSR) chains. Ovarian tumor growth and metastasis were increased in the presence of laminin-1 plus either AG73 peptide, IKVAV, or A13, and were significantly reduced in the presence of A12 or YIGSR. Expression of Bcl-2 and Mdm2 was higher by 3.5- and about 100-fold, respectively, in ovarian tumors grown in the presence of laminin compared to tumors grown in the presence of gelatin. Moreover, peptides A13 and AG73 further elevated Bcl-2 expression by 6- and 7-fold respectively, while IKVAV yielded expression similar to laminin-1. YIGSR and A12 reduced the expression of Bcl-2 by 7- and 3-fold, respectively, compared to treatment with laminin-1. A13 and AG73 increased Mdm2 expression by 1.8- and 1.3-fold, respectively, while IKVAV, A12, and YIGSR were without effect. Thus, laminin-1 exerts its proliferative effect on the development of ovarian tumors via upregulation of survival genes such as Bcl-2 and Mdm2. Peptides A13 and AG73 (which increased tumor growth and spread) enhance the expression of these genes and A12 and YIGSR (which decrease tumor growth and spread) attenuate their expression. IKVAV probably enhances tumor growth and metastasis by another mechanism.

Role of basement membrane in tumor growth and metastasis

The basement membrane is a thin extracellular matrix produced by epithelial and endothelial cells. It is biologically active for normal epithelial cell differentiation. Basement membrane promotes the growth of tumor cells in vitro and in vivo when coinjected. Laminin, the major biologically active component, also increases tumor growth and the malignant phenotype by promoting increased cell growth and protease activity. Using systematic peptide screening with synthetic peptides covering the entire laminin molecule, several active sites in laminin have been identified that regulate tumor growth and metastasis.

Human cell lines as an in vitro/in vivo model for prostate carcinogenesis and progression

BACKGROUND

The study of prostate carcinogenesis and tumor progression is made difficult by the lack of appropriate in vitro and in vivo models. High prevalence of prostatic intra-epithelial neoplasia and latent prostatic carcinoma, representing multiple steps in carcinogenesis to invasive carcinoma, are relevant targets for cancer prevention. From the RWPE-1, immortalized, non-tumorigenic, human prostate epithelial cell line, we have derived four tumorigenic cell lines with progressive malignant characteristics.

METHODS

Cell lines were derived by exposure of RWPE-1 to N-methyl-N-nitrosourea (MNU), selected and cloned in vivo and in vitro, and characterized by prostatic epithelial and differentiation markers, karyotype analysis, anchorage-independent growth, invasiveness, tumorigenicity, and pathology of the derived tumors.

RESULTS

Cytokeratins 8 and 18, androgen receptor, and prostate-specific antigen expression in response to androgen, confirm prostatic epithelial origin. RWPE-1 cells do not grow in agar and are not tumorigenic in mice, but the growth, tumorigenicity, and tumor pathology of the MNU cell lines correlate with their invasive ability. The WPE1-NA22 (least malignant) form small, well-differentiated, and WPE1-NB26 cells (most malignant) form large, poorly differentiated, invasive tumors. Overall, loss of heterozygosity for chromosomes 7q, 13q, 18q, and 22, and gain of 5, 9q, 11q, and 20, was observed. The MNU cell lines, in order of increasing malignancy are; WPE1-NA22, WPE1-NB14, WPE1-NB11, and WPE1-NB26.

CONCLUSIONS

This family of cell lines with a common lineage represents a unique and relevant model which mimics stages in prostatic intra-epithelial neoplasia (PIN) and progression to invasive cancer, and can be used to study carcinogenesis, progression, intervention, and chemoprevention.

Laminin-1 and alpha6beta1 integrin regulate acinar morphogenesis of normal and malignant human prostate epithelial cells

BACKGROUND

Cell-matrix interactions via integrin receptors are critical for acinar morphogenesis. The non-tumorigenic, human prostate epithelial cell line RWPE-1 was used in a three-dimensional (3D) cell culture model to identify the matrix protein and its integrin receptor required for acinar morphogenesis.

METHODS

3D cultures, immunostaining, confocal microscopy, and Western blot analysis were used to examine acinar formation on matrix proteins and to determine integrin receptor expression.

RESULTS

RWPE-1 cells differentiate into acini of polarized cells with a distinct lumen in 3D Matrigel culture. In contrast, the malignant WPE1-NB26 prostate epithelial cells form solid cell masses. In 3D gels of laminin-1, type IV collagen, or fibronectin, RWPE-1 cells form acini only in laminin-1. Anti-laminin-1 antibody reduces acinar formation in a dose-dependent manner. Polarized RWPE-1 cells showed basal expression of alpha6 and beta1 integrin subunits. Blocking antibodies to alpha6 or beta1 reduced acinar formation to 9 and 6 percent of control, respectively. The beta1 integrin colocalized with focal adhesion kinase (FAK). Inhibition of extracellular signal-regulated kinase kinase activity significantly reduced acinar formation to 38 percent of control, suggesting that beta1 integrin-mediated signal transduction may be regulated through a FAK pathway.

CONCLUSIONS

While basal expression of alpha6beta1 integrin in RWPE-1 cells correlates with their ability to polarize and form acini, a decrease or loss of alpha6, and diffused beta1 expression in WPE1-NB26 cells correlates with loss of acinar-forming ability. Results show that laminin-1 and a functional alpha6beta1 integrin receptor are required for acinar morphogenesis. This novel 3D cell culture model is useful for elucidating regulation of acinar morphogenesis and its loss during prostate carcinogenesis.

Nitric oxide mediates laminin-induced neurite outgrowth in PC12 cells

Laminin is a potent stimulator of neurite outgrowth in a variety of primary neurons and neuronal cell lines. Here, we investigate the role of nitric oxide in the signaling mechanism of laminin-mediated neurite outgrowth in the PC12 cell line. Within 8 s of exposure to laminin, PC12 cells produce nitric oxide. Peak laminin-induced nitric oxide levels reach 8 nM within 12 s of exposure to laminin and constitutive nitric oxide production is sustained for 1 min. A neurite outgrowth promoting synthetic peptide (AG73), derived from the laminin-1-alpha globular domain, also stimulated nitric oxide release. The nitric oxide synthase inhibitor, 1-NAME, prevents the formation of nitric oxide and here, 1-NAME inhibited both laminin-mediated and AG73-mediated neurite outgrowth by 88 and 95%, respectively. In contrast, C16, a synthetic peptide derived from the laminin-1-gamma chain, is shown here to promote PC12 cell attachment, but not neurite outgrowth. Interestingly, the C16 peptide did not activate nitric oxide release, suggesting that laminin-induced nitric oxide release in PC12 cells is associated only with neurite outgrowth promoting laminin domains and signals. In addition, the data here show that the nitric oxide released by PC12 cells in response to laminin is required as a part of the mechanism of laminin-mediated neurite outgrowth.

PKC and ERK1/2 regulate amylase promoter activity during differentiation of a salivary gland cell line

The addition of transforming growth factor alpha (TGFalpha) to a human submandibular gland cell line (HSG) cultured on basement membrane extract Matrigel, synergistically activates the acinar cell-specific salivary amylase promoter. Signaling through beta1 integrins and increased phosphorylation of ERK1/2 are involved in the increased promoter activity. Phorbol-12-myristate-13-acetate (PMA) and thapsigargin increase amylase promoter activity, suggesting that phorbol ester and calcium-dependent protein kinase C (PKC) pathways are also involved. The combination of specific inhibitors of PKC and MEK1 inhibits the amylase promoter. Inhibitors of the calcium-dependent PKC isoforms alpha, beta, and gamma decrease the promoter activity; however, PKCbeta is not detectable in HSG cells. TGFalpha alters the cellular localization of PKCalpha but not -gamma, suggesting PKCalpha is involved in TGFalpha upregulation of the amylase promoter. Furthermore, rottlerin, a PKCdelta-specific inhibitor, increases the promoter activity, suggesting PKC isoforms differentially regulate the amylase promoter. In conclusion, beta1-integrin and TGFalpha signaling pathways regulate the amylase promoter activity in HSG cells. In response to Matrigel and TGFalpha, the activation of both PKCalpha and phosphorylation of ERK1/2 results in synergistic activation of the amylase promoter. Published 2000 Wiley-Liss, Inc.

New thiol and sulfodiimine metalloproteinase inhibitors and their effect on human microvascular endothelial cell growth

Matrix metalloproteinases (MMPs, matrixins) are a family of homologous zinc endopeptidases that may play a very important role in many physiological and pathological processes, e.g., the initiation of angiogenesis. Two new matrixin inhibitors were synthesized and characterized. A thiol inhibitor MAG-283 had IC(50) values of 480, 3, 280, 14, 1.1, and 2.3 nM against human interstitial collagenase (MMP-1), gelatinase A (MMP-2), stromelysin (MMP-3), matrilysin (MMP-7), neutrophil collagenase (MMP-8), and gelatinase B (MMP-9), respectively. A sulfodiimine inhibitor YLL-224 had IC(50) values of 180, 63, 4500, 210, 5.9, and 44 nM against MMP-1, -2, -3, -7, -8, and -9, respectively. Human skin microvascular endothelial cells were treated with these two compounds in culture. These inhibitors at very low micromolar concentrations suppressed proliferation of the endothelial cells stimulated by acidic fibroblast growth factor and vascular endothelial growth factor. They also partially blocked cell invasion through type IV collagen. These results suggested a correlation between the anti-metalloenzyme activity and the effects of these inhibitors on the growth and invasion of endothelial cells.

Neural cell response to multiple novel sites on laminin-1

The basement membrane protein laminin-1 is a potent stimulator of neurite outgrowth for a variety of neuronal cell types. Previous studies have identified neurite outgrowth activity in several distinct regions of the laminin-1 molecule. In this study, 545 overlapping 12- to 14-mer synthetic peptides, corresponding to most of the amino acid sequence of the alpha1, beta1, and gamma1 chains of laminin-1, were screened for cell attachment and neurite outgrowth activity using primary cultures of mouse cerebellar granule neurons and two neuronal cell lines. We identified 48 peptides derived from novel regions of the laminin-1 molecule that were positive for neural cell adhesion activity. Only the cerebellar cells were found to have true neurite outgrowth activity with certain of the peptides, whereas some peptides induced short spike-like process with the cell lines. Although 23 of these peptides were active on all 3 cell types screened, 25 others showed cell-type specificity in their activity. These studies show that (1) there are multiple and distinct sites on laminin-1 for cell adhesion and neurite-like outgrowth and (2) that there are neural cell-type-specific active domains. The multiple active sites found explains, in part, the potent activity of laminin-1 on neurite outgrowth.

Human endothelial cells express CCR2 and respond to MCP-1: direct role of MCP-1 in angiogenesis and tumor progression

Although several CXC chemokines have been shown to induce angiogenesis and play roles in tumor growth, to date, no member of the CC chemokine family has been reported to play a direct role in angiogenesis. Here we report that the CC chemokine, monocyte chemotactic protein 1 (MCP-1), induced chemotaxis of human endothelial cells at nanomolar concentrations. This chemotactic response was inhibited by a monoclonal antibody to MCP-1. MCP-1 also induced the formation of blood vessels in vivo as assessed by the chick chorioallantoic membrane and the matrigel plug assays. As expected, the angiogenic response induced by MCP-1 was accompanied by an inflammatory response. With the use of a rat aortic sprouting assay in the absence of leukocytic infiltrates, we ruled out the possibility that the angiogenic effect of MCP-1 depended on leukocyte products. Moreover, the direct effect of MCP-1 on angiogenesis was consistent with the expression of CCR2, the receptor for MCP-1, on endothelial cells. Assessment of supernatant from a human breast carcinoma cell line demonstrated the production of MCP-1. Treatment of immunodeficient mice bearing human breast carcinoma cells with a neutralizing antibody to MCP-1 resulted in significant increases in survival and inhibition of the growth of lung micrometastases. Taken together, our data indicate that MCP-1 can act as a direct mediator of angiogenesis. As a chemokine that is abundantly produced by some tumors, it can also directly contribute to tumor progression. Therefore, therapy employing antagonists of MCP-1 in combination with other inhibitors of angiogenesis may achieve more comprehensive inhibition of tumor growth.

Cell adhesive sequences in mouse laminin beta1 chain

Laminin-1, a major component of the basement membrane, consists of three different chains, alpha1, beta1, and gamma1. We sought to identify cell adhesive sequences from the mouse laminin beta1 chain by testing HT-1080 fibrosarcoma and B16-F10 melanoma cells for binding to 187 overlapping synthetic peptides which covered the entire chain. Fourteen peptides showed cell adhesive activities with either peptide-conjugated Sepharose beads or peptide-coated plates or both. Additional cells, including neuronal, endothelial, and salivary gland cells, showed biological responses in a cell type-specific manner. B-7, B-133, and B-160 showed the most potent cell attachment. Cell binding on three peptides (B-34, B-133, and B-160) was inhibited by EDTA. Cell adhesion to 11 of the 12 active peptides was inhibited to varying degrees by heparin. Of the 17 active peptides identified in the laminin beta1 chain in this and other studies, 8 are clustered on the amino terminal globular domain, suggesting a possible important role in cell binding for this domain that may be multifunctional. These data demonstrate that the laminin beta1 chain has multiple active sites for cell adhesion, some of which are cell-type specific.

Bioadhesive peptides as potential anticancer drug carriers: activation via isopeptide deblocking by proteases

BACKGROUND

Bioadhesive peptides are potentially useful as anticancer drug carriers, if the bioadhesivity becomes active only at the tumor site. We propose that this function can be achieved by the prodrug strategy using proteases in tumors.

MATERIALS AND METHODS

A laminin fragment peptide, Ac-AASIKVAVSADR-NH2 (5), and its derivatives, Ac-AASIK(L) VAVSADR-NH2 (6), Ac-AASIDpm(NH2)VAVSADR-NH2 (7) and Ac-AASIDpm(L)(NH2)VAVSADR-NH2 (8), were synthesized and tested for their bioadhesive activity with 6 cancer cell lines.

RESULTS

The strength of the binding was in the order of 5 >> 7 > or = 8 > or = 6. The attachment of mouse whole blood cells to peptide 6-coated surface was also weaker than to 5-coated surface. The Leu isopeptide linkage in 6 was enzymatically cleaved by the cells.

CONCLUSION

The present results suggest that isopeptide 6, working as a prodrug form for the bioadhesive peptide 5, could serve as an anticancer drug carrier for tumor targeting.

Impaired wound repair and delayed angiogenesis in aged mice

Wound repair is a multistep process consisting of hemostasis, inflammatory cell infiltration, tissue regrowth, and remodeling. In aged individuals, this progression of events is altered, resulting in wounds that heal more slowly than wounds in the young. These studies were designed to examine the proliferative phase of repair in young and aged mice, with attention to the angiogenic process. Using a standardized excisional injury model, wound re-epithelialization, collagen accumulation, and angiogenesis were examined. Re-epithelialization and collagen synthesis were substantially delayed in aged mice as compared with young mice. Angiogenesis in wounds from aged mice was also delayed, with significantly more capillary growth in wounds from young mice than aged mice. In addition, wounds from aged mice contained significantly less of the angiogenic mediators fibroblast growth factor-2 (FGF-2) and vascular endothelial growth factor (VEGF) than wounds from young animals (p < 0.05). Because macrophages are a rich source of angiogenic factors in wounds, macrophage production of VEGF was examined. Macrophages from aged mice produced significantly less VEGF than cells from young mice. To examine the in vivo endothelial cell responsiveness, a defined amount of rFGF-2 was suspended in Matrigel and placed subcutaneously in either young or aged mice. In response to FGF-2, capillary growth into Matrigel was significantly less in aged than young mice. The results suggest that a decline in angiogenic growth factor production, as well as a decline in endothelial responsiveness to specific factors, may account for the delayed wound angiogenesis in aged mice. These results also indicate that age-related alterations in macrophage function might partially account for the overall delay in the wound repair process.

Angiogenic activity of human soluble intercellular adhesion molecule-1

Serum levels of soluble intercellular adhesion molecule-1 (sICAM-1) are elevated in a number of pathological conditions associated with angiogenesis, including tumor growth. Because the increased levels of sICAM-1 suggested that it may be angiogenic, we tested the ability of sICAM-1 to promote angiogenesis. Human recombinant sICAM-1 stimulates chemokinetic endothelial cell migration, endothelial cell tube formation on Matrigel, and sprouting of aortic rings. sICAM-1 also mediates angiogenesis in the chick chorioallantoic membrane assay. Additionally, we found a Mr 49,000 molecule that binds to sICAM-1 that may be the surface ligand on endothelial cells. The evidence that sICAM-1 has angiogenic activity suggests a possible role linking inflammation and neovascularization. Furthermore, sICAM-1 may enhance tumor growth by promoting angiogenesis and escape from immunosurveillance.

Osteonectin promotes prostate cancer cell migration and invasion: a possible mechanism for metastasis to bone

The mechanism underlying the "organ-specific" metastasis of prostate cancer cells to the bone is still poorly understood. It is not clear whether the cells only invade the bone and proliferate there or whether they invade many tissues but survive mainly in the bone ("seed and soil"). Extracts from various organs were used as chemoattractants in the in vitro chemotaxis and invasion assays. Results show that, in comparison with extracts of other tissues, bone extracts promote a 2- to 4-fold increase in chemotaxis by human prostate epithelial cells and a 4-fold increase in the invasive ability of human prostate carcinoma cells. The purified active factor from bone and from marrow stromal-cell-conditioned medium is a low glycosylated osteonectin that specifically promotes the invasive ability of bone-metastasizing prostate (and breast) cancer cells but not that of non-bone-metastasizing tumor cells. It does not stimulate the growth of prostate cancer cells in vitro or in vivo. Because osteonectin specifically enhances matrix metalloprotease activity in prostate and breast cancer cells (and not in other tumor cell types), we conclude that prostate cancer cell metastasis to the bone is, in part, mediated by the ability of osteonectin to promote migration, protease activity, and invasion.

Thymosin beta4 accelerates wound healing

Angiogenesis is an essential step in the repair process that occurs after injury. In this study, we investigated whether the angiogenic thymic peptide thymosin beta4 (Tbeta4) enhanced wound healing in a rat full thickness wound model. Addition of Tbeta4 topically or intraperitoneally increased reepithelialization by 42% over saline controls at 4 d and by as much as 61% at 7 d post-wounding. Treated wounds also contracted at least 11% more than controls by day 7. Increased collagen deposition and angiogenesis were observed in the treated wounds. We also found that Tbeta4 stimulated keratinocyte migration in the Boyden chamber assay. After 4-5 h, migration was stimulated 2-3-fold over migration with medium alone when as little as 10 pg of Tbeta4 was added to the assay. These results suggest that Tbeta4 is a potent wound healing factor with multiple activities that may be useful in the clinic.

Reconstituted basement membrane reduces proliferation and increases prolactin expression of GH3 cells

This study investigated the effects of reconstituted basement membrane Matrigel on the proliferation and prolactin expression of GH3 cells in culture for 6 days. When cells were cultured on Matrigel, the initial attachment was increased but the cell number was not changed with time whereas rapid increase in cell number was observed in cultures on plastic. Bromodeoxyuridine (BrdU)-labeling showed that BrdU incorporation ratio of GH3 cells cultured on Matrigel was about one half of that observed with cells cultured on plastic (9.7+/-0.7% vs. 18.7+/-1.2%). Immunocytochemistry revealed that the ratio of the prolactin-immunoreactive GH3 cells was about 3.6 times (58.4+/-2.9% on Matrigel vs. 16.2+/-1.4% on plastic), which was compatible with the results of Western blot analysis. In situ hybridization demonstrated that prolactin mRNA-positive cells were identified more frequently when cells were cultured on Matrigel compared to cultures on plastic. These findings indicate that Matrigel is a proper culture substrate for the long-term culture of GH3 pituitary cells due to the inhibition of overgrowth and promotion of prolactin expression.

Gp38k, a protein synthesized by vascular smooth muscle cells, stimulates directional migration of human umbilical vein endothelial cells

Gp38k is a 383-amino-acid secreted glycoprotein expressed by cultured vascular smooth muscle cells during the time of transition from a proliferating monolayer culture to a nonproliferating multilayered (differentiated) culture. Expression continues as the cell culture forms multicellular nodules. Because this transition period involves active cell migration, we evaluated the effects of exogenously added gp38k on vascular endothelial cell (HUVEC) migration and chemotaxis. Here we demonstrate that gp38k acts as a chemoattractant for HUVECs and stimulates cell migration in Boyden chambers at a level comparable to that achieved with the known endothelial cell chemoattractant bFGF. The migration effect is neutralized by the presence of a polyclonal anti-gp38k antibody. Because gp38k expression is also correlated with changes in culture morphology, we also assessed its ability to act as an agonist of HUVEC morphology using cultures growing on Matrigel. We report that gp38k stimulates endothelial cell tubulogenesis in this assay system. These results provide the first evidence that gp38k may function in angiogenesis by stimulating the migration and reorganization of vascular endothelial cells.

Cutting edge: a short polypeptide domain of HIV-1-Tat protein mediates pathogenesis

HIV-1 encodes the transactivating protein Tat, which is essential for virus replication and progression of HIV disease. However, Tat has multiple domains, and consequently the molecular mechanisms by which it acts remain unclear. In this report, we provide evidence that cellular activation by Tat involves a short core domain, Tat21-40, containing only 20 aa including seven cysteine residues highly conserved in most HIV-1 subtypes. Effective induction by Tat21-40 of both NF-kappaB-mediated HIV replication and TAR-dependent transactivation of HIV-long terminal repeat indicates that this short sequence is sufficient to promote HIV infection. Moreover, Tat21-40 possesses potent angiogenic activity, further underscoring its role in HIV pathogenesis. These data provide the first demonstration that a 20-residue core domain sequence of Tat is sufficient to transactivate, induce HIV replication, and trigger angiogenesis. This short peptide sequence provides a potential novel therapeutic target for disrupting the functions of Tat and inhibiting progression of HIV disease.

Laminin-1-adherent cancer cells show increased proliferation and decreased apoptosis in vivo

BACKGROUND

The growth rate of a tumor is dependent on both cell proliferation and cell loss. We have established subpopulations of human colon cancer cells with different in vivo growth rates by selecting the cells according to their adhesiveness to laminin-1 in vitro.

MATERIALS AND METHODS

Laminin-1-adhesion selected colon cancer cells were injected into the cecal wall of nude mice. The tumors were examined 30 days later. Cell proliferation was assessed by proliferating cell nuclear antigen (PCNA) index and apoptotic cells were labeled by digoxigenin-11-dUTP using terminal deoxynucleotidyl transferase.

RESULTS

The laminin-1-adherent cells, which formed larger tumors in vivo, showed increased proliferative activity and reduced apoptosis in comparison with the laminin-1-nonadherent cells.

CONCLUSION

Laminin-1 may enhance the malignant behavior of colon cancer cells by accelerating proliferation as well as by decreasing cell loss.

Development of intracytoplasmic lumens in a colon cancer cell line cultured on a non-adhesive surface

Cell-matrix interactions have important effects on phenotypic features, such as morphology, differentiation and cell growth. Several papers have suggested that when cell-matrix interactions are interrupted, cells grow as multicellular spheroids and eventually undergo apoptosis. We found that when ET(-), a laminin non-adherent colon cancer cell line, was cultured on poly-2-hydroxyethyl methacrylate (HEMA) coated plastic, the cells floated as cellular aggregates of spheroids or as single cells. Some of the single cells contained a very large intracytoplasmic lumen (ICL) and appeared similar to signet ring cells. These ICL were lined by a layer of short microvilli. The number of the cell did not increased cells when cultured on poly-HEMA. Another type of single cells, usually without ICL, demonstrated the characteristics of apoptotic cells by histologic examination. Acridine orange staining, flow cytometry and electron microscopy confirmed the apoptotic nature of those cells. In immunohistochemical staining for proliferating cell nuclear antigen, spheroids of cells and single cells with ICL were immunoreactive, while most of the single cells without ICL were negative. These results suggest that multicellular aggregation and formation of ICL were induced by the adaptation of ET(-) colon cancer cells in a harmful environment caused by reduced adhesiveness, and these changes might be related to cell survival.

Identification of metastasis-promoting sequences in the mouse laminin alpha 1 chain

Laminin-1, a major basement membrane matrix glycoprotein, enhances adhesion, migration, and metastasis of tumor cells. We have screened 208 overlapping synthetic peptides covering the short and long arms of mouse laminin alpha1 chain for their adhesion activity with B16-F10 mouse melanoma cells. Cell adhesion activity was determined using various amounts of peptides coated on plastic dishes and by measuring cell adhesion on peptide-conjugated Sepharose beads. Nineteen peptides showed B16-F10 cell adhesion activity. Three peptides, designated A-13, -24, and -208, showed the strongest attachment activity in the plate assay, whereas 4 peptides, A-13, -51, -99, and -112, demonstrated the strongest cell adhesion when conjugated to beads. The 19 peptides were tested in vivo for their effect on experimental pulmonary metastasis by B16-F10 cells. Four peptides, A-13, -51, -64, and -119, significantly enhanced metastasis, with A-13 showing the strongest dramatic enhancement. The four metastasis-promoting peptides also stimulated migration of B16-F10 cells in the Boyden chamber assay in vitro with A-13 being the most potent stimulator. In addition, the 4 peptides inhibited laminin-induced cell attachment and migration, which indicates that these four sequences are possible functional B16-F10 cell binding sites in laminin-1. All the four sequences are located on the globular domains of the short arm. Other peptides, including strong adhesion-active peptides, A-24, -99, -112, and a scrambled A-13 peptide, did not stimulate either migration or metastasis. Thus, laminin-1 has multiple active sites in the globular domains of the short arm which promote migration and metastasis of B16-F10 cells.

Interferon-alpha may exacerbate cryoblobulinemia-related ischemic manifestations: an adverse effect potentially related to its anti-angiogenic activity

The discovery of the strong association between hepatitis C virus (HCV) infection and the development of mixed cryoglobulinemia has motivated active testing of antiviral-directed alternative therapies. Several trials have demonstrated that classic cryoglobulinemia-associated manifestations improve with interferon-alpha (IFNalpha) treatment. Herein we report on 3 HCV-infected patients with severe cryoglobulinemia-related ischemic manifestations who were closely followed up during IFNalpha therapy. Clinical evaluations with special attention to ischemic lesions, liver function tests, and cryocrit determinations were serially performed. In addition to prednisone and immunosuppressive agents, the patients received IFNalpha at 3 x 10(6) units, 3 times per week for 2 months, 3 months, and 4 months, respectively. In all 3 patients, systemic features improved, liver function results returned to normal, and cryocrit values decreased. However, ischemic lesions became less vascularized and ischemia progressed, leading to transmetatarsal and subcondylar amputation, respectively, in 2 of the patients and fingertip necrosis and ulcer enlargement in the third. Skin biopsies performed before IFNalpha therapy and after 2 months of IFNalpha therapy in the third patient showed a significant decrease in subepidermal microvessels. When IFNalpha was discontinued, the lesions finally healed. Cryoglobulinemia-related ischemic lesions may worsen during IFNalpha treatment, presumably through a decrease in inflammation-induced angiogenesis. The anti-angiogenic activity of IFNalpha may delay the appropriate healing of ischemic lesions.

Interferon-alpha may exacerbate cryoblobulinemia-related ischemic manifestations: an adverse effect potentially related to its anti-angiogenic activity

The discovery of the strong association between hepatitis C virus (HCV) infection and the development of mixed cryoglobulinemia has motivated active testing of antiviral-directed alternative therapies. Several trials have demonstrated that classic cryoglobulinemia-associated manifestations improve with interferon-alpha (IFNalpha) treatment. Herein we report on 3 HCV-infected patients with severe cryoglobulinemia-related ischemic manifestations who were closely followed up during IFNalpha therapy. Clinical evaluations with special attention to ischemic lesions, liver function tests, and cryocrit determinations were serially performed. In addition to prednisone and immunosuppressive agents, the patients received IFNalpha at 3 x 10(6) units, 3 times per week for 2 months, 3 months, and 4 months, respectively. In all 3 patients, systemic features improved, liver function results returned to normal, and cryocrit values decreased. However, ischemic lesions became less vascularized and ischemia progressed, leading to transmetatarsal and subcondylar amputation, respectively, in 2 of the patients and fingertip necrosis and ulcer enlargement in the third. Skin biopsies performed before IFNalpha therapy and after 2 months of IFNalpha therapy in the third patient showed a significant decrease in subepidermal microvessels. When IFNalpha was discontinued, the lesions finally healed. Cryoglobulinemia-related ischemic lesions may worsen during IFNalpha treatment, presumably through a decrease in inflammation-induced angiogenesis. The anti-angiogenic activity of IFNalpha may delay the appropriate healing of ischemic lesions.

Identification of endothelial cell binding sites on the laminin gamma 1 chain

The laminins belong to a family of trimeric basement membrane glycoproteins with multiple domains, structures, and functions. Endothelial cells bind laminin-1 and form capillary-like structures when plated on a laminin-1-rich basement membrane matrix, Matrigel. Laminin-1 is composed of 3 chains, alpha1, beta1, and gamma1. Because laminin-1 is known to contain multiple biologically active sites, we have screened 156 synthetic overlapping peptides spanning the entire laminin gamma1 chain for potential angiogenic sequences. Only 7 of these peptides, designated as C16, C25, C30, C38, C64, C75, and C102, disrupted the formation of capillary-like structures by human umbilical vein endothelial cells on Matrigel. Dose-response experiments in the presence of 50 to 200 microg/mL showed that tube formation was prevented by most peptides at 150 and 200 microg/mL, except for C16, which showed strong activity at all concentrations. Active peptides promoted vessel sprouting from aorta rings and angiogenesis in the chick chorioallantoic membrane assay. In addition, the active peptides also promoted endothelial cell adhesion to dishes coated with 0.1 microg of peptide and inhibited attachment to laminin-1 but not to plastic or fibronectin. Four of the active peptides, C25, C38, C75, and C102, may have cell-type specificity with endothelial cells, since they did not promote PC12 neurite outgrowth or adhesion of B16-F10 melanoma and human submandibular gland cells. These results suggest that specific laminin gamma1-chain peptides have angiogenic activity with potential therapeutic applications.