Probing glycosaminoglycan spectral signatures in live cells and their conditioned media by Raman microspectroscopy.

Spectroscopic markers characteristic of reference glycosaminoglycan molecules were identified previously based on their vibrational signatures. Infrared spectral signatures of glycosaminoglycans in fixed cells were also recently demonstrated but probing live cells still remains challenging. Raman microspectroscopy is potentially interesting to perform studies under physiological conditions. The aim of the present work was to identify the Raman spectral signatures of GAGs in fixed and live cells and in their conditioned media. Biochemical and Raman analyses were performed on five cell types: chondrocytes, dermal fibroblasts, melanoma (SK-MEL-28), wild type CHO, and glycosaminoglycan-defective mutant CHO-745 cells. The biochemical assay of sulfated GAGs in conditioned media was only possible for chondrocytes, dermal fibroblasts, and wild type CHO due to the detection limit of the test. In contrast, Raman microspectroscopy allowed probing total glycosaminoglycan content in conditioned media, fixed and live cells and the data were analysed by principal component analysis. Our results showed that the Raman technique is sensitive enough to identify spectral markers of glycosaminoglycans that were useful to characterise the conditioned media of the five cell types. The results were confirmed at the single cell level on both live and fixed cells with a good differentiation between the cell types. Furthermore, the principal component loadings revealed prominent glycosaminoglycan-related spectral information. Raman microspectroscopy allows monitoring of the glycosaminoglycan profiles of single live cells and could therefore be developed for cell screening purposes and holds promise for identifying glycosaminoglycan signatures as a marker of cancer progression in tissues.

Elastin peptides regulate HT-1080 fibrosarcoma cell migration and invasion through an Hsp90-dependent mechanism.

BACKGROUND: The elastin-derived peptides (EDPs) exert protumoural activities by potentiating the secretion of matrix metalloproteinases (MMP) and the plasminogen-plasmin activating system. In the present paper, we studied heat-shock protein 90 (Hsp90) involvement in this mechanism. METHODS: HT-1080 fibrosarcoma cell migration and invasion were studied in artificial wound assay and modified Boyden chamber assay, respectively. Heat-shock protein 90 was studied by western blot and immunofluorescence. Matrix metalloproteinase-2 and urokinase plasminogen activator (uPA) were studied by gelatin ± plasminogen zymography and immunofluorescence. Heat-shock protein 90 partners were studied by immunoprecipitation. Messenger RNA expression was studied using real-time PCR. Small interfering RNAs were used to confirm the essential role of Hsp90. RESULTS: We showed that kappa-elastin and VGVAPG elastin hexapeptide stimulated Hsp90, pro-MMP-2 and uPA secretion within 6 h, whereas AGVPGLGVG and GRKRK peptides had no effect. No increase of mRNA level was observed. Heat-shock protein 90-specific inhibitors inhibit EDP-stimulated HT-1080 cell-invasive capacity and restrained EDP-stimulated pro-MMP-2 and uPA secretions. The inhibitory effect was reproduced by using Hsp90-blocking antibody or Hsp90 knockdown by siRNA. Heat-shock protein 90 interacted with and stabilised uPA and pro-MMP-2 in conditioned culture media of HT-1080 fibrosarcoma cells. CONCLUSIONS: Taken together, our results demonstrate that EDPs exert protumoural activities through an Hsp90-dependent mechanism involving pro-MMP-2 and uPA.

Analytical methods for measuring collagen XIX in human cell cultures, tissue extracts, and biological fluids.

Type XIX collagen is a minor collagen associated with basement membranes in vascular, neuronal, mesenchymal, and epithelial tissues. We demonstrated that the NC1, C-terminal, domain of collagen XIX inhibits the migration capacities of tumor cells and exerts a strong inhibition of tumor growth. Other basement membrane collagens or derived fragments were measured in biological fluids such as blood and urine of patients and appeared to be useful for diagnosis, prognosis, or treatment monitoring. The aim of this study was to develop and validate methods to measure collagen XIX and its fragments in human cell cultures, tissue extracts, and human biological fluids. For that purpose, we developed real-time PCR, Western blot, and competitive enzyme-linked immunosorbent assays. We demonstrated that the methods developed in this paper are specific for collagen XIX. We showed that it is expressed in human cell cultures, tissue extracts, and various biological fluids. These methods may be used in various human tissue extracts and biological fluids such as serum, amniotic fluid, cord blood, and many other fluids. Collagen XIX or its fragments could constitute new biomarkers for human diseases as well as for diagnosis and/or prognosis.

Encapsulation of contrast imaging agents by polypropyleneimine-based dendrimers.

Polypropyleneimines (PPIs) functionalized by glycerol-based entities are prepared and characterized by diffusion-ordered spectroscopy NMR. Showing low cytotoxicity against MRC5 fibroblasts, their encapsulation capacities of gadolinium complexes was evaluated. T(1) measurements were performed to determine the relaxivity of the encapsulated gadopentetate dimeglumine (GdBOPTA) in dendrimers of fourth and fifth generation (GD-PPI-4 and GD-PPI-5). Comparison of the GdBOPTA relaxivity and the relaxivity of GdBOPTA-loaded dendrimers showed a slight increase of the gadolinium chelate relaxivity.

Lumican inhibits B16F1 melanoma cell lung metastasis.

BACKGROUND: Lumican is a small leucine-rich proteoglycan (SLRP) of the extracellular matrix (ECM) involved in the control of melanoma growth and invasion. The aim of the present study was to analyse the role of lumican in the regulation of the development of lung metastasis. METHODS: B16F1 melanoma cells stably transfected with lumican expressing plasmid (Lum-B16F1) were injected to syngenic mice. The lung metastasis was compared to mice injected with mock-transfected B16F1 cells (Mock-B16F1). The expression of lumican, cyclin D1, apoptotic markers, vascular endothelium growth factor (VEGF) and Von Willebrand Factor (vWF) within lung metastasis nodules was investigated by immunohistochemistry. In parallel, cells cultured in presence of lumican were assayed for apoptosis and motility. RESULTS: We observed that the number and the size of lung metastasis nodules were significantly decreased in mice injected with Lum-B16F1 cells in comparison to Mock-B16F1 cells. This was associated with an increase of tumour cell apoptosis within metastasis nodules but the cell proliferation rate remained constant in the two mice groups. In contrast, the VEGF immunostaining and the number of blood vessels within the lung metastasis nodules were decreased in the lumican-expressing tumours. In vitro, a significant decrease of apoptotic markers in wild type B16F1 cells incubated with increasing amounts of lumican core protein was observed. In addition, pseudotubes formation on Matrigel(R) and the migratory capacity of endothelial cells was inhibited by lumican. Altogether, our results indicate that lumican decreases lung metastasis development not only by inducing tumour cell apoptosis but also by inhibiting angiogenesis.

17Beta-oestradiol up-regulates the expression of a functional UDP-glucose dehydrogenase in articular chondrocytes: comparison with effects of cytokines and growth factors.

OBJECTIVES: To investigate the mechanisms by which cytokines and 17beta-oestradiol (17beta-E2) modulate gene expression and activity of uridine diphosphoglucose dehydrogenase (UGDH), a key enzyme of GAG synthesis in articular chondrocytes. METHODS: Rabbit articular chondrocytes (RAC) from 3-week-old animals were incubated for 24 h with TGF-beta, insulin like growth factor-I (IGF-I), IL-1beta, IL-6 and 17beta-E2. GAG synthesis was measured by [35S]-sulphate labelling and the expression of the UGDH gene was estimated by both real-time polymerase chain reaction and western blotting, whereas the enzyme activity was assayed by a spectrophotometric procedure. In addition, the transcriptional activity of several UGDH gene promoter constructs was determined in RAC transiently transfected with wild-type or deleted human oestrogen receptor-alpha gene (hER alpha66 or hER alpha46, respectively). RESULTS: 17Beta-E2 and its receptor hER alpha66 enhanced GAG neosynthesis in rabbit articular chondrocytes, as did TGF-beta1 whereas IL-1beta decreased this synthesis. 17Beta-E2 was found to exert positive regulatory effects at mRNA, protein and UGDH activity levels. In addition, the receptor hER alpha66, but not hER alpha46, increased the transcriptional activity of the UGDH gene. In contrast, no clear correlation between transcription, translation and activity of the UGDH was found under the effects of the cytokines studied. However, TGF-beta enhanced the enzyme activity, whereas IL-1beta, IL-6 and IGF-I were without significant effect. CONCLUSIONS: 17Beta-E2 enhanced GAG synthesis in chondrocytes via up-regulation of the UGDH gene expression and enzyme activity. These data provide insights into the molecular mechanisms involved in the regulation of the UGDH gene and offer new approaches to investigate its potential alteration in joint diseases.

Expression of lumican, a small leucine-rich proteoglycan with antitumour activity, in human malignant melanoma.

BACKGROUND: The family of small leucine-rich proteoglycans (SLRPs), which includes decorin, lumican, biglycan and fibromodulin, constitutes an abundant component of the skin extracellular matrix. We previously demonstrated that human lumican inhibits melanoma growth and progression in a mouse experimental model, by regulating cell migration, proliferation and apoptosis. AIM: The aim of this study was to investigate the expression of lumican and decorin in human malignant melanoma and adjacent peritumoral tissue, to understand better their role in the control of growth and invasion of human melanoma. METHODS: Expression of both proteoglycans was studied by immunohistochemistry using specific antibodies in 34 malignant melanomas, 12 Hutchinson's melanotic freckles and 4 cutaneous metastatic melanomas. RESULTS: We showed that lumican and decorin are located in the dermis and in the peritumoral stroma of malignant melanoma, but are not found in melanoma cells or dense tumour tissue. In the healthy dermis, distant from the tumour, the increasing ratio of lumican to decorin was inversely correlated with the proliferation of the tumour cells (P = 0.035). The comparison of the level of expression of lumican protein in superficial vs. nodular subtypes of malignant melanomas showed a decrease of lumican but not decorin in the peritumoral stroma of nodular subtypes. In the peritumoral stroma, the level of expression of lumican but not decorin decreased significantly (P = 0.016) with increasing Clark levels. In addition, immunocytochemical and reverse transcription PCR analyses of malignant melanoma cell lines (A-375, HT-144) and of MRC-5 and dermal fibroblasts from healthy donors in vitro confirmed that dermal fibroblasts are responsible for lumican and decorin synthesis in skin. CONCLUSIONS. Lumican may regulate vertical progression of human malignant melanoma, but further study is necessary to clarify the antitumour mechanism and the downstream signal transduction pathways involved.

Cell surface proteoglycan expression during maturation of human monocytes-derived dendritic cells and macrophages.

Cell surface proteoglycans play an important part in the functional and metabolic behaviour of leucocytes. We studied the expression of cell surface proteoglycans in human monocytes, in monocyte-derived immature and mature dendritic cells and in macrophages by metabolic labelling with [(35)S]-sulphate, reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blotting. Immature dendritic cells had the highest metabolic activity for the synthesis of cell surface proteoglycans. The major part of these proteoglycans was in phosphatidylinositol-anchored form and was released after treatment with phospholipase C. A minor part was released by trypsin. Digestion with chondroitinase ABC and mild HNO(2) treatment showed that cell surface proteoglycans had a higher proportion of chondroitin sulphate, both in the phospholipase C and trypsin fractions, suggesting that at least some glypicans contained chondroitin sulphate chains. RT-PCR detected the transcripts of glypicans 1, 3, 4 and 5 and all syndecans. Immature dendritic cells expressed a most complex spectrum of glypicans and syndecans, glypican-1 and syndecan-1 being expressed preferentially by this type of cells. Mature dendritic cells expressed glypican-3, which was not present in other lineages. These results suggest that different mononuclear cells synthesize cell surface proteoglycans actively with characteristic expression of different syndecans and glypicans genes, depending on the degree of cell differentiation and/or maturation.

[Role of matrikins in melanoma progression]. / Rôle des matrikines dans la progression du mélanome.

Expression of melanoma invasiveness, ultimately leading to the formation of metastases, requires that cancer cells break through the successive skin barriers (dermo-epidermal junction, dermis) constituted of various extracellular matrix constituents. In order to facilitate their progression, melanoma cells express, in concert with stromal cells, a group of proteolytic systems which degrade this extracellular structures. However, proteolysis of basement membrane, collagen or elastic fibers can uncover cryptic sites or/and liberate matrix fragments whose properties appeared distinct from their intact macromolecule counterparts. Those fragments, called matrikines, are able to empede or to accelerate melanoma progression ex vivo and in vivo. Non-collagenous domains of basement membrane collagens, which behave like potent "matstatins", are seen as potential pharmacological agents in melanoma.

Matrikines in the regulation of extracellular matrix degradation.

The term "matrikines" was coined for designating peptides liberated by partial proteolysis of extracellular matrix macromolecules, which are able to regulate cell activities. Among these peptides, some of them may modulate proliferation, migration, protease production, or apoptosis. In this review, we summarize the activity of matrikines derived from elastin and interstitial or basement membrane collagens on the regulation of matrix metalloproteinases expression and/or activation, and on the plasminogen/plasmin system. Due to their activity, matrikines may play a significant role in physiological or pathological processes such as wound healing or tumor invasion.

[Serum protein immunofixation in malignant hemopathies other than multiple myeloma and Waldenstrom's macroglobulinemia]. / Immunofixation des protéines sériques dans les hémopathies malignes autres que le myélome multiple et la maladie de Waldenström.

The interest of serum protein immunofixation in myeloma and Waldenstr m's macroglobulinemia is widely known. It is not so well defined in other malignant hemopathies. The purpose of this study was to determine immunofixation abnormalities in malignant hemopathies other than multiple myeloma and Waldenstr m's macroglobulinemia. We selected serum immunofixations of 61 patients affected by malignant hemopathies and 53 patients affected by other pathologies susceptible to give immunofixation's alterations. We showed that the frequency of immunofixation abnormalities was more important in patients affected by malignant hemopathies than in patients affected by other pathologies (70.5% vs 35.8%). A high frequency of monoclonal immunoglobulins was found in patients with lymphoma (53.3%) and oligoclonal immunoglobulins in other hemopathies (48.2%). No significant difference of the frequency of the monoclonal immunoglobulin isotypes was found. In summary, this retrospective study demonstrates a high frequency of immunofixation abnormalities in malignant hemopathies other than multiple myeloma and Waldenstr m's macroglobulinemia and different immunofixation characteristics between lymphomas and other hemopathies.

Human mast cells stimulate fibroblast proliferation, collagen synthesis and lattice contraction: a direct role for mast cells in skin fibrosis.

BACKGROUND: Mast cells, the key cells of immediate hypersensitivity type reactions, have also been postulated to have a central role in influencing tissue remodelling and fibrosis occurring in the skin. OBJECTIVE: Our aim was to investigate the direct role of human mast cells (HMC) in skin fibrotic processes, by assessing the effects of the addition of the human mast cell line HMC-1 to human skin fibroblasts, and to identify the responsible mediators. METHODS: HMC-1 sonicates were added to human skin fibroblasts and the following parameters were evaluated: proliferation ([3H]-thymidine), collagen synthesis ([3H] proline), activity of matrix metalloproteinases (MMPs) (zymography) and tissue inhibitors of metalloproteinases (TIMPs) (reverse zymography), and collagen gel contraction. RESULTS: HMC-1 sonicate increased significantly both proliferation and collagen production in the human skin fibroblasts and these properties were not affected by heating of the sonicate (56 degrees C, 30 min, or 100 degrees C, 3 min). Two main mast cell mediators, histamine and tryptase, were found to be responsible for the increase in fibroblast proliferation and collagen production. HMC-1 sonicate did not display any pre-formed gelatinase activity, and its addition to the fibroblasts did not change their pro-MMP-2 and MMP-2 activity. On the other hand, HMC-1 were found to possess TIMP-1 and TIMP-2. Addition of HMC-1 had no effect on fibroblasts TIMP-1 but induced a dose-dependent increase of TIMP-2 activity. In addition, HMC-1 sonicate seeded together with the fibroblasts in tri-dimensional collagen gel significantly enhanced their contraction. CONCLUSION: We have shown that human mast cells, by granule-stored and therefore quickly releasable mediators, increase human skin fibroblast proliferation, collagen synthesis, TIMP-2 and collagen gel contraction. Therefore, mast cells have a direct and potentiating role in skin remodelling and fibrosis.

Nerve growth factor displays stimulatory effects on human skin and lung fibroblasts, demonstrating a direct role for this factor in tissue repair.

Nerve growth factor (NGF) is a polypeptide which, in addition to its effect on nerve cells, is believed to play a role in inflammatory responses and in tissue repair. Because fibroblasts represent the main target and effector cells in these processes, to investigate whether NGF is involved in lung and skin tissue repair, we studied the effect of NGF on fibroblast migration, proliferation, collagen metabolism, modulation into myofibroblasts, and contraction of collagen gel. Both skin and lung fibroblasts were found to produce NGF and to express tyrosine kinase receptor (trkA) under basal conditions, whereas the low-affinity p75 receptor was expressed only after prolonged NGF exposure. NGF significantly induced skin and lung fibroblast migration in an in vitro model of wounded fibroblast and skin migration in Boyden chambers. Nevertheless NGF did not influence either skin or lung fibroblast proliferation, collagen production, or metalloproteinase production or activation. In contrast, culture of both lung and skin fibroblasts with NGF modulated their phenotype into myofibroblasts. Moreover, addition of NGF to both fibroblast types embedded in collagen gel increased their contraction. Fibrotic human lung or skin tissues displayed immunoreactivity for NGF, trkA, and p75. These data show a direct pro-fibrogenic effect of NGF on skin and lung fibroblasts and therefore indicate a role for NGF in tissue repair and fibrosis.

Modulation of sulfated glycosaminoglycan and small proteoglycan synthesis by the extracellular matrix.

Cell culture in collagen lattice is known to be a more physiological model than monolayer for studying the regulation of extracellular matrix protein deposition. The synthesis of sulfated glycosaminoglycans (GAG) and dermatan sulfate (DS) proteoglycans by 3 cell strains were studied in confluent monolayers grown on plastic surface, in comparison to fully retracted collagen lattices. Cells were labelled with 35S-sulfate, followed by GAG and proteoglycan analysis by cellulose acetate and SDS-polyacrylamide gel electrophoresis, respectively. The 3 cell strains contracted the lattice in a similar way. In monolayer cultures, the major part of GAG was secreted into culture medium whereas in lattice cultures of dermal fibroblasts and osteosarcoma MG-63 cells but not fibrosarcoma HT-1080 cells, a higher proportion of GAGs, including dermatan sulfate, was retained within the lattices. Small DS proteoglycans, decorin and biglycan, were detected in fibroblasts and MG-63 cultures. They were preferentially trapped within the collagen gel. In retracted lattices, decorin had a higher Mr than in monolayer. Biglycan was detected in monolayer and lattice cultures of MG-63 cells but in lattice cultures only in the case of fibroblasts. In this last case, an up regulation of biglycan mRNA steady state level and down regulation of decorin mRNA was observed, in comparison to monolayers, indicating that collagen can modulate the phenotypical expression of small proteoglycan genes.

A specific sequence of the noncollagenous domain of the alpha3(IV) chain of type IV collagen inhibits expression and activation of matrix metalloproteinases by tumor cells.

The invasive properties of melanoma cells correlate with the expression of matrix metalloproteinases (MMPs) and their physiological modulators (tissue inhibitors of metalloproteinase and membrane-type MMPs) and with that of the alphaVbeta3 integrin. We investigated the effect of anterior lens capsule type IV collagen and of the alpha3(IV) collagen chain on the invasive properties of various tumor cell lines (HT-144 melanoma cells, HT-1080 fibrosarcoma cells). We demonstrated that anterior lens capsule type IV collagen or specifically the synthetic peptide alpha3(IV) 185-203 inhibited both the migration of melanoma or fibrosarcoma cells as well as the activation of membrane-bound MMP-2 by decreasing the expressions of MT1-MMP and the beta3 integrin subunit.

Biochemical alterations of uterine leiomyoma extracellular matrix in type IV Ehlers-Danlos syndrome.

Collagens and glycosaminoglycans were assessed in 6 leiomyomas from otherwise healthy ("control") patients and 1 leiomyoma from a patient with type IV Ehlers-Danlos syndrome. The type IV Ehlers-Danlos leiomyoma contained less type III collagen and dermatan sulfate than control leiomyomas. This might contribute to the formation of a defective collagen network in type IV Ehlers-Danlos syndrome.

Transforming growth factor beta-1 up-regulates clusterin synthesis in thyroid epithelial cells.

Porcine epithelial cells in primary culture seeded on plastic substratum form a monolayer containing pseudo-vesicles. When cultured in the presence of thyreotropin (TSH) thyrocytes adopted a follicular-like structure and formed clusters. Transforming growth factor beta-1 (TGFbeta1) induced a rapid spreading of the TSH-treated cells only. At the same time, TGFbeta1 enhanced clusterin protein and mRNA expression. The increase of clusterin synthesis was proportional to the TGFbeta1 concentration in the culture medium. Tunicamycin abolished the up-regulation of whole clusterin synthesis and morphological changes. The activator protein-1 binding site partly directed the TGFbeta1-stimulated clusterin expression. Phorbol ester caused rapid spreading of the cells with disappearance of vesicular and follicular structures. It decreased clusterin mRNA and protein expression, but increased Mr 45, 000 protein secretion in both TSH-treated and nontreated cells. Up-regulation of clusterin expression may be a marker of TGFbeta-mediated thyrocyte dedifferentiation.

Influence of oleic acid on the expression, activation and activity of gelatinase A produced by oncogene-transformed human bronchial epithelial cells.

Invasiveness and metastatic capacity of tumor cells have been related to increased expression and activation of gelatinase-A (MMP-2). 9-octadecenoic acid (oleic acid, OA), a long-chain cis-unsaturated fatty acid, has been shown to partially inhibit the formation of lung metastatic colonies in an ex vivo model of implantation of metastatic cells into nude mice. Reduction of metastasis formation was suggested to be due to a decrease of MMP-2 activity in tumor tissue extracts. Since regulation of MMP-2 activity occurs at different levels, including gene expression, pro-enzyme activation and finally active enzyme inhibition, we here investigated the precise level of the inhibitory effect of OA on MMP-2 activity by oncogene-transformed human bronchial epithelial cells (BZR cells). OA, at the dose of 5 x 10(-5) M, was shown to inhibit by 50% MMP-2 activity released from BZR cells. Northern-blot analysis of mRNA encoding MMP-2, MT1-MMP, the physiological activator of MMP-2, and TIMP-2, the natural inhibitor of MMP-2, revealed that OA did not alter the steady-state levels of MMP-2, MT1-MMP and TIMP-2 mRNA. Also, gelatin zymography demonstrated that the extent of MMP-2 activation was not modified by OA treatment. On the contrary, OA could inhibit the fluorogenic quenching substrate (7-methoxycoumarin-4-yl)acetyl-L-Pro-Leu-Gly-Leu-[N-3-(2,4-dinitrophenyl)-L-2, 3-diaminopropionyl]-Ala-Arg-NH2 (Mca-Pro-Leu-Gly-Leu-Dpa-Ala-Arg-NH2) hydrolysis by recombinant MMP-2 with Ki = 4.3 microM. These data suggest that the beneficial influence of OA on the formation of lung metastatic colonies was independent of its influence on MMP-2 expression and/or activation, but could be attributed to inhibition of MMP-2 activity.

Expression and activation of pro-gelatinase A by human melanoma cell lines with different tumorigenic potential.

The production of various proteolytic enzymes by tumor cells facilitate the invasion of solid tumors into surrounding tissues. We examined three cell lines (M1Dor, M4Be and M3Da) derived from malignant melanoma which exhibited different abilities to grow in nude mice following subcutaneous grafting. By in vitro invasion assay using Boyden-chambers technique, we found that none of those cell lines were able to invade the Matrigel. Several studies have substantiated the role of matrix metalloproteinases (MMP), mainly gelatinases MMP-9 and MMP-2, in melanoma cell invasion. Each cell line constitutively produced MMP-2 (but not MMP-9) in its latent form only, with stronger production for the most tumorigenic cell line in vivo (M3Da). Integrity of the MMP-2 activation process was studied since MMP-2 was also recovered as zymogen at the cell plasma membrane. All cell lines secreted TIMP-1 and TIMP-2 in a constitutive manner and again, but TIMP-2 production as well as MT1-MMP expression were found inversely related to their tumorigenic potential. Plating cells onto type I or type IV collagen did not trigger pro-MMP-2 activation; on the contrary, conversion of pro-MMP-2 to its active form could be evidenced when melanoma cell lines were seeded in a three dimensional type I collagen lattice.

[Regulation of cell activity by the extracellular matrix: the concept of matrikines]. / Régulation de l'activité cellulaire par la matrice extracelulaire: le concept de matrikines.

The activity of connective tissue cells is modulated by a number of factors present in their environment. In addition to the soluble factors such as hormones, cytokines or growth factors, cells also receive signals from the surrounding extracellular matrix (ECM) macromolecules. Moreover, they may degrade the ECM proteins and liberate peptides which may by themselves constitute new signals for the surrounding cells. Therefore, an actual regulation loop exists in connective tissue, constituted by peptides generated by ECM degradation and connective tissue cells. The term of "matrikine" has been proposed to designate such ECM-derived peptides able to regulate cell activity. In this review, we summarize some data obtained in our laboratory with two different matrikines: the tripeptide glycyl-histidyl-lysine (GHK) and the heptapeptide cysteinyl-asparaginyl-tyrosyl-tyrosyl-seryl-asparaginyl-serine (CNYYSNS). GHK is a potent activator of ECM synthesis and remodeling, whereas CNYYSNS is able to inhibit polymorphonuclear leukocytes activation and decrease the invasive capacities of cancer cells.