Human TIMP-3 is expressed during fetal development, hair growth cycle, and cancer progression

Hypertension Promotes the Proliferation and Migration of ccRCC Cells by Downregulation of TIMP3 in Tumor Endothelial Cells through the miR-21-5p/TGFBR2/P38/EGR1 Axis

Recent studies have demonstrated that hypertension correlates with tumorigenesis and prognosis of clear-cell renal cell carcinoma (ccRCC); however, the underlying molecular mechanisms remain unclear. By analyzing bulk and single-cell RNA sequencing data and experimental examining of surgical excised ccRCC samples, we found that tissue inhibitors of metalloproteinases 3 (TIMP3), a pivotal paracrine factor in suppressing tumor progression, was significantly reduced in the tumor endothelial cells of patients with hypertensive ccRCC. Besides, in tumor xenograft of NCG mouse model, compared with saline normotensive group the expression of TIMP3 was significantly decreased in the angiotensin II-induced hypertension group. Treating human umbilical vein endothelial cells (HUVEC) with the plasma of patients with hypertensive ccRCC and miR-21-5p, elevated in the plasma of patients with hypertensive ccRCC, reduced the expression of TIMP3 compared with normotensive and control littermates. We also found that the inhibition of TIMP3 expression by miR-21-5p was not through directly targeting at 3'UTR of TIMP3 but through suppressing the expression of TGFβ receptor 2 (TGFBR2). In addition, the knockout of TGFBR2 reduced TIMP3 expression in HUVECs through P38/EGR1 (early growth response protein 1) signaling axis. Moreover, via coculture of ccRCC cell lines with HUVECs and mouse tumor xenograft model, we discovered that the TIMP3 could suppress the proliferation and migration of ccRCC.

IMPLICATIONS

Overall, our findings shed new light on the role of hypertension in promoting the progression of ccRCC and provide a potential therapeutic target for patients with ccRCC with hypertension.

Matrix metalloproteinases in keratinocyte carcinomas

The incidence of cutaneous keratinocyte-derived cancers is increasing globally. Basal cell carcinoma (BCC) is the most common malignancy worldwide, and cutaneous squamous cell carcinoma (cSCC) is the most common metastatic skin cancer. BCC can be classified into subtypes based on the histology, and these subtypes are classified further into low- and high-risk tumors. There is an increasing need to identify new therapeutic strategies for the treatment of unresectable and metastatic cSCC, and for aggressive BCC variants such as infiltrating, basosquamous or morpheaform BCCs. The most important risk factor for BCC and cSCC is solar UV radiation, which causes genetic and epigenetic alterations in keratinocytes. Similar gene mutations are noted already in sun-exposed normal skin emphasizing the role of the alterations in the tumor microenvironment in the progression of cSCC. Early events in cSCC progression are alterations in the composition of basement membrane and dermal extracellular matrix induced by influx of microbes, inflammatory cells and activated stromal fibroblasts. Activated fibroblasts promote inflammation and produce growth factors and proteolytic enzymes, including matrix metalloproteinases (MMPs). Transforming growth factor-β produced by tumor cells and fibroblasts induces the expression of MMPs by cSCC cells and promotes their invasion. Fibroblast-derived keratinocyte growth factor suppresses the malignant phenotype of cSCC cells by inhibiting the expression of several MMPs. These findings emphasize the importance of interplay of tumor and stromal cells in the progression of cSCC and BCC and suggest tumor microenvironment as a therapeutic target in cSCC and aggressive subtypes of BCC.

Melanoma-Derived Exosomes Endow Fibroblasts with an Invasive Potential via miR-21 Target Signaling Pathway

Background

Tumor-derived exosomes are messengers that participate in tumor progression. Fibroblasts are associated with the metastasis of cancer depending on their cellular plasticity. We hypothesize that tumor-derived exosomes endow the fibroblasts in tumor microenvironment with invasive phenotype to the benefit of tumor metastasis.

Materials and Methods

Exosomes derived from B16-F10 cells were identified by nanoparticle tracking analyzer (NTA), dynamic light scattering (DLS), Western blot (WB), and transmission electron microscopy (TEM). Cell invasion and migration assays were performed using the xCELLigence real-time cell analyzer (RTCA). Role of tumor-derived exosomal miR-21 in cell invasion was determined by qPCR.

Results

The invasion analysis showed that exosome-treated fibroblast cells had greater invasive capability as compared to untreated fibroblast cells, with the higher expressions of MMP2 and MMP9. miR-21 is at least partially responsible for this effect. After ingestion of melanoma-derived exosomes during incubation, mouse embryonic fibroblasts cells emerged cellular invasiveness with the presentation of a marked increase in miR-21 expression. MiR-21 promoted invasion of fibroblasts by down-regulation of tissue inhibitor of metalloproteinase 3 (TIMP3) expression and increasing of matrix metalloprotein (MMP) expression in fibroblast cells via melanoma-derived exosomes in a time-dependent manner.

Conclusion

Our results suggest that tumor-derived exosomes may facilitate stromal fibroblasts an aggressive phenotype to equip the tumor progression.

Transcriptomic analyses of regenerating adult feathers in chicken

Background

Feathers have diverse forms with hierarchical branching patterns and are an excellent model for studying the development and evolution of morphological traits. The complex structure of feathers allows for various types of morphological changes to occur. The genetic basis of the structural differences between different parts of a feather and between different types of feather is a fundamental question in the study of feather diversity, yet there is only limited relevant information for gene expression during feather development.

Results

We conducted transcriptomic analysis of five zones of feather morphologies from two feather types at different times during their regeneration after plucking. The expression profiles of genes associated with the development of feather structure were examined. We compared the gene expression patterns in different types of feathers and different portions of a feather and identified morphotype-specific gene expression patterns. Many candidate genes were identified for growth control, morphogenesis, or the differentiation of specific structures of different feather types.

Conclusion

This study laid the ground work for studying the evolutionary origin and diversification of feathers as abundant data were produced for the study of feather morphogenesis. It significantly increased our understanding of the complex molecular and cellular events in feather development processes and provided a foundation for future studies on the development of other skin appendages.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-015-1966-6) contains supplementary material, which is available to authorized users.

Epigenetic changes of TIMP-3, GSTP-1 and 14-3-3 sigma genes as indication of status of chronic inflammation and cancer

OBJECTIVES

This study aimed to compare the epigenetic changes via hypermethylation status of TIMP-3, GSTP-1 and 14-3-3σ genes, between healthy subjects and patients with reversible chronic inflammatory disease, and between healthy subjects and patients with irreversible malignant disease, to highlight the genetic changes that occur in the progression from an inflammatory condition to irreversible genetic changes commonly observed in cancer patients.

METHODS

DNA was extracted from the blood of 680 healthy subjects, and tissues and blood of 110 patients with chronic inflammation disease of the gums, as well as neoplastic tissues of 108 breast cancer patients. Methylation-specific polymerase chain reaction (PCR) for TIMP-3, GSTP-1 and 14-3-3σ was performed, and hypermethylation status was analyzed and compared between the 3 groups.

RESULTS

The hypermethylation frequencies of TIMP-3 and GSTP-1 of reversible chronic inflammatory gum disease and the control group were similar, but both were significantly lower than those for malignant disease patients (p<0.0001). The methylation frequency of 14-3-3σ in chronic inflammatory gum disease was higher than in the cancer and control groups (p<0.0001). The methylation of CpG islands in TIMP-3 and GSTP-1 in chronic inflammation patients occurred as frequently as in the control group, but less frequently than in breast cancer patients. However, the epigenetic silencing of 14-3-3σ occurred more frequently in the chronic inflammation group than in cancer patients and healthy controls.

CONCLUSIONS

The epigenetic silencing of 14-3-3σ might be essential for chronic inflammatory gum disease. The epigenetic changes presented in chronic inflammation patients might demonstrate an irreversible destruction in the tissues or organs similar to cancer.

Immunohistochemical analysis of TIMP-3 and MMP-9 in actinic keratosis, squamous cell carcinoma of the skin, and basal cell carcinoma

The expression of metalloproteinases and their inhibitors has been related to different invasive and metastatic potentials in cancer. This study aims to investigate the immunohistochemical expression of TIMP-3 and MMP-9 in samples of basal cell carcinoma (BCC), squamous cell carcinoma of the skin (SCC), and actinic keratosis (AK). Immunohistochemistry was performed to evaluate the expression of TIMP-3 and MMP-9 in samples of BCC (n=22), SCC (n=10), and AK (n=15). Ten fields of both tumor parenchyma and tumor stroma were photographed and counted in image software. The ratio of positive cells to total cells was used to quantify the staining. A higher expression of MMP-9 was found in tumor stroma of SCC compared to BCC and AK. No significant differences in TIMP-3 expression were observed among the groups. Considering the well-described differences between these neoplasms, these results provide additional evidence of the role of MMP-9 in tumor invasiveness of keratinocyte-derived tumors.

Modulation in proteolytic activity is identified as a hallmark of exogen by transcriptional profiling of hair follicles

Exogen is the process by which the hair follicle actively sheds its club fiber from the follicle. However, little is known about signals that govern the cellular mechanisms of shedding. Here, we have identified factors that are important in regulating either the retention or release of the hair club fiber from its epithelial silo within the follicle. Using the vibrissa follicle as our model, we isolated follicle segments containing club fibers and surrounding follicle tissue at different time points before their natural release from the hair follicle. We then performed microarray analysis to identify key molecular changes as the club fiber approached final release. Among the different classes of genes that were identified, we found changes in the expression pattern of protease inhibitors and proteases, suggesting that proteolysis may mediate fiber release, either through terminal differentiation or proteolytic cleavage. We validated transcriptional changes using reverse transcription-PCR, and further immunofluorescence analysis indicated that protease inhibitors surrounding the club fiber may have an important role in regulating the process of club fiber shedding. Our findings also highlighted that molecular differentiation of the innermost layer of cells immediately surrounding the club fiber, the companion(CL), is likely to be important in hair shedding.

From buds to follicles: matrix metalloproteinases in developmental tissue remodeling during feather morphogenesis

Organogenesis involves a series of dynamic morphogenesis and remodeling processes. Since feathers exhibit complex forms, we have been using the feather as a model to analyze how molecular pathways and cellular events are used. While several major molecular pathways have been studied, the roles of matrix degrading proteases and inhibitors in feather morphogenesis are unknown. Here we addressed this knowledge gap by studying the temporal and spatial expression of proteases and inhibitors in developing feathers using mammalian antibodies that cross react with chicken proteins. We also investigated the effect of protease inhibitors on feather development employing an in vitro feather bud culture system. The results show that antibodies specific for mammalian MMP2 and TIMP2 stained positive in both feather epithelium and mesenchyme. The staining co-localized in structures of E10-E13 developing feathers. Interestingly, MMP2 and TIMP2 exhibited a complementary staining pattern in developing E15 and E20 feathers and in maturing feather filaments. Although they exhibited a slight delay in feather bud development, similar patterns of MMP2 and TIMP2 staining were observed in in vitro culture explants. The broad spectrum pharmacological inhibitors AG3340 and BB103 (MMP inhibitors) but not Aprotinin (a plasmin inhibitor) showed a reversible effect on epithelium invagination and feather bud elongation. TIMP2, a physiological inhibitor to MMPs, exhibited a similar effect. Markers of feather morphogenesis showed that MMP activity was required for both epithelium invagination and mesenchymal cell proliferation. Inhibition of MMP activity led to an overall delay in the expression of molecules that regulate either early feather bud growth and/or differentiation and thereby produced abnormal buds with incomplete follicle formation. This work demonstrates that MMPs and their inhibitors are not only important in injury repair, but also in development tissue remodeling as demonstrated here for the formation of feather follicles.

Alterations in type I hemidesmosome components suggestive of epigenetic control in the salivary glands of patients with Sjögren's syndrome

Objective

Acinar cells in the salivary glands of patients with Sjögren's syndrome (SS) display severe alterations in anchorage to the basal lamina. Bioinformatics analysis of the BP230 gene sequence has revealed the presence of CpG islands that might be involved in epigenetic control of gene expression, and methylation of the BP230 promotor region may be implicated as an epigenetic control mechanism in salivary gland damage. Thus, the present study was undertaken to evaluate the protein BP230, as well as proteins BP180, α6β4 integrin, and cytokeratin‐18, for their expression levels, localization, and ability to form hemidesmosome adhesion complexes.

Methods

Eighteen patients with primary SS and 14 healthy control subjects were studied. Levels of messenger RNA (mRNA) and protein were measured by reverse transcription–polymerase chain reaction and Western blotting, respectively. BP230 methylation was determined by methylation‐sensitive polymerase chain reaction. Protein complexes were analyzed by immunoprecipitation and assessed for localization by immunofluorescence.

Results

In patients with SS as compared with controls, BP230 mRNA levels were decreased while protein levels were increased, and the gene promotor region was hypermethylated. Augmented proteolysis of BP180 was detected, since levels of linear IgA disease fragment 1 were increased. The complex‐forming ability of BP230, BP180, α6β4 integrin, and cytokeratin‐18 was maintained in patients with SS, in contrast to that in controls. BP230 and BP180 colocalized at the basal membrane of acinar cells, and cleavage of BP180 coincided with a loss of colocalization.

Conclusion

The decrease in BP230 mRNA levels may be explained by gene hypermethylation. We postulate that local epigenetic modifications of BP230 are produced in response to factors present in the damaged salivary glands of patients with SS. Additionally, the paradoxical increase in BP230 protein levels and the formation of both normal and altered adhesion complexes may help avoid cell death induced by the loss of anchorage.

Differential gene and protein expression of tissue inhibitors of metalloproteinases (TIMP)-3 and TIMP-4 in gingival tissues from drug induced gingival overgrowth

OBJECTIVES

The purpose of this study was to analyse mRNA expression and protein localization of tissue inhibitors of metalloproteinases (TIMP)-3 and TIMP-4 in gingival tissues removed from drug (calcium-channel blocker) induced gingival overgrowth and periodontitis patients.

DESIGN

Employing RT-PCR, we evaluated TIMP-3 and TIMP-4 mRNA levels of 20 human gingival tissue samples taken from patients suffering gingival overgrowth (GO) and periodontitis (P). Then, using immunohistochemistry we investigated the TIMP-3 and TIMP-4 protein localization of five sample tissues from each group.

RESULTS

TIMP-4 mRNA levels in GO-gingiva tended to be lower than in P-gingiva but the results differed little (p = 0.22). Varying degrees of inflammation in the protein localization of TIMP-3 and TIMP-4 were found. TIMP-4 immunoreactivity (IR) was weak in the endothelial cells, fibroblasts, epithelial basal and parabasal cells while the degree of inflammation differed as well. TIMP-3 and TIMP-4 IR in inflammatory cells, including lymphocytes, plasma cells, and macrophages, were faint and intense respectively. For P-gingiva, both TIMP-3 and TIMP-4 IR expression was weak in the endothelial cells, fibroblasts, basal and parabasal epithelial layers. Expression of TIMP-3 was faint in the inflammatory cells, whereas TIMP-4 IR was strong.

CONCLUSION

Our findings suggest that TIMP-3 and TIMP-4 expression differs in GO and P-gingival tissues, both of which are potentially involved in pathogenesis.

Tissue inhibitor of matrix metalloproteinase-3 levels in the extracellular matrix of lung, kidney, and eye increase with age

Tissue inhibitor of matrix metalloproteinase-3 (TIMP-3) is an important regulator of matrix metalloproteinase activity in many types of disease, including atherosclerosis, neoplasia, and inflammatory conditions. Among TIMPs, TIMP-3 uniquely binds the extracellular matrix (ECM). We performed IHC staining on 17 tissue microarrays containing >1500 samples to determine the location of ECM TIMP-3 staining in a variety of predominantly vascular tissues. We found a unique pattern of TIMP-3 staining in the ECM of renal arterioles, small pulmonary vessels and parenchyma, and Bruch's membrane in the retina. There was no staining in larger caliber arteries including coronary and internal mammary arteries. TIMP-3 protein accumulation was found to be an age-dependent phenomenon, with staining appearing in all three tissues in early adulthood and becoming more robust among the elderly. These findings may help to explain the late onset of the TIMP-3-associated ocular diseases Sorsby fundus dystrophy and age-related macular degeneration and suggest a similar phenomenon could be at work in other age-related conditions.

Tissue inhibitor of metalloproteinases-3 promoter methylation is an independent prognostic factor for bladder cancer

PURPOSE

TIMP-3 (tissue inhibitor of metalloproteinases-3) is 1 of 4 members of a family of proteins that were originally classified according to their ability to inhibit matrix metalloproteinases. We analyzed TIMP-3 methylation in 175 urine sediment DNA samples from patients with bladder cancer with well characterized clinicopathological parameters, including patient outcome.

MATERIALS AND METHODS

We examined urine sediment DNA for aberrant methylation of 9 genes, including TIMP-3, by quantitative fluorogenic real-time polymerase chain reaction.

RESULTS

Using an optimal cutoff value by TaqMan(R) quantitation we found that the risk of death was statistically significantly higher in patients with higher TIMP-3 and ARF methylation (HR 1.99, 95% CI 1.12 to 3.27, p = 0.01 and HR 1.66, 95% CI 1.00 to 2.76, p = 0.05, respectively) than in patients without/lower TIMP3 and ARF methylation in urine. A significant correlation was also seen between the risk of death and stage 3 tumor (HR 2.73, 95% CI 1.58 to 4.72, p = 0.003) and metastasis (HR 3.32, 95% CI 1.98 to 5.57, p = 0.0001). Multivariate analysis subsequently revealed that TIMP-3 methylation was an independent prognostic factor for bladder cancer survival with stage and metastasis (p = 0.001 and 0.02, respectively).

CONCLUSIONS

These results suggest that TIMP-3 promoter methylation could be a clinically applicable marker for bladder cancer progression.

Prognostic significance of matrix metalloproteinases-1, -2, -7 and -13 and tissue inhibitors of metalloproteinases-1, -2, -3 and -4 in colorectal cancer

Strong expression of many matrix metalloproteinases (MMPs) has been related to poor survival of colorectal cancer (CRC) patients. The expression of tissue inhibitors of metalloproteinases (TIMPs) has been associated with both a beneficial and a poor outcome and there is thus a need to further clarify the significance of MMPs and TIMPs in CRC. The prognostic significance of 4 MMPs and TIMPs in CRC was evaluated. Formalin-fixed, paraffin-embedded tissue arrayed samples of 351 patients with primary colon or rectal cancer of Dukes' stages A-D were selected for immunohistochemical staining of MMP-1, -2, -7 and -13, and TIMP-1, -2, -3 and -4. High expression of MMP-2 in the malignant epithelium as well as in the surrounding stroma was associated with reduced survival of colon cancer patients. Strong epithelial and stromal cytoplasmic staining of TIMP-3 was associated with a longer survival in rectal cancer patients, and here the interobserver variation for evaluating the degree of staining was lower than for epithelial staining. Strong stromal cytoplasmic staining of TIMP-4 predicted longer survival of rectal cancer patients. Multivariate analysis showed that stromal cytoplasmic TIMP-3 staining was the only marker of independent prognostic value. MMP-2 might be a useful prognostic marker in colon cancer, and TIMP-3 and TIMP-4 in rectal cancer, but the findings associated with stromal staining should be interpreted with some caution. Different biologic behavior or different genetic development may explain the differences between colon and rectal cancers regarding the expression of MMP-2, TIMP-3 and TIMP-4.

Molecular fingerprinting of BMP2- and BMP4-treated embryonic maxillary mesenchymal cells

OBJECTIVE

To determine the differences in gene expression between control-, bone morphogenetic protein (BMP)2- and BMP4-treated murine embryonic maxillary mesenchymal (MEMM) cells.

DESIGN

Transcript profiles of BMP2-, BMP4- and vehicle-treated MEMM cells were compared utilizing the murine high-density GeneChip arrays from Affymetrix. The raw chip data (probe intensities) were pre-processed using robust multichip averaging with GC-content background correction and further normalized with GeneSpring v7.2 software. Cluster analysis of the microarray data was performed with the GeneSpring software. Changes in the gene expression were verified by TaqMan quantitative real-time PCR.

RESULTS

Expression of approximately 50% of the 45 101 genes and expressed sequence tags examined in this study were detected in BMP2-, BMP4- and vehicle-treated MEMM cells and that of several hundred genes was significantly altered (up or downregulated) in these cells in response to BMP2 and BMP4. Expression profiles of each of the 26 mRNAs tested by TaqMan quantitative real-time PCR were found to be consistent with the microarray data. Genes whose expression was modulated following BMP2 or BMP4 treatment, could be broadly classified based on the functions of the encoded proteins such as the growth factors and signaling molecules, transcription factors, and proteins involved in epithelial-mesenchymal interactions, extracellular matrix synthesis, cell adhesion, proliferation, differentiation, and apoptosis.

CONCLUSION

Utilization of the Affymetrix GeneChip microarray technology has enabled us to delineate a detailed transcriptional map of BMP2 and BMP4 responsiveness in embryonic maxillary mesenchymal cells and offers revealing insights into crucial molecular regulatory mechanisms employed by these two growth factors in orchestrating embryonic orofacial cellular responses.

Collagenase-1 (MMP-1), matrilysin-1 (MMP-7), and stromelysin-2 (MMP-10) are expressed by migrating enterocytes during intestinal wound healing

BACKGROUND

Matrix metalloproteinases (MMPs) play a crucial role in wound healing of the skin, airways, and cornea, but data on MMPs in normal intestinal wound healing is limited. The aim of this study was to clarify the role of collagenase-1 (MMP-1), matrilysin-1 (MMP-7), and stromelysin-2 (MMP-10) in intestinal wound repair and to determine the effect of cytokines on the expression of these MMPs in intestinal epithelial cell lines.

METHODS

Surgical specimens from patients with ischemic colitis (n = 5) were used as an in vivo model of intestinal re-epithelialization. Fetal ileal explants were used as an ex vivo model. In situ hybridization for MMPs -1, -3, -7, and -10 was performed and immunohistochemical stainings were used to localize MMP-7 and -9 expressing cells. Stainings for cytokeratin and laminin-5 were performed to identify epithelial cells and migrating enterocytes, respectively. Caco-2, HT-29, and WiDr cell lines were treated for 6-48 h with different cytokines (e.g. EGF, KGF, IL-1 beta, TGF-alpha, TNF-alpha, and TGF-beta1) and Taqman real-time quantitative RT-PCR was used to investigate their effect on the expression of MMPs-1, -7, and -10.

RESULTS

MMP-7, MMP-10, and MMP-1 were expressed by migrating enterocytes bordering intestinal ulcers in 5/5, 3/5, and 3/5 samples, respectively. In the fetal gut model, MMP-1 and MMP-10 were expressed by migrating enterocytes, but matrilysin-1 expression was not detected. Matrilysin-1 was up-regulated by TNF-alpha and IL-1 beta, and stromelysin-2 by TNF-alpha and EGF in Caco-2 and WiDr cell cultures. MMP-1 was up-regulated in Caco-2 cells by TGF-beta, EGF, and IL-1 beta, but only by EGF in WiDR cells.

CONCLUSIONS

It is concluded that collagenase-1, stromelysin-2, and matrilysin-1 are involved in intestinal re-epithelialization in vivo and that they are up-regulated by cytokines relevant in wound repair.

Matrix remodeling during endochondral ossification

Endochondral ossification, the process by which most of the skeleton is formed, is a powerful system for studying various aspects of the biological response to degraded extracellular matrix (ECM). In addition, the dependence of endochondral ossification upon neovascularization and continuous ECM remodeling provides a good model for studying the role of the matrix metalloproteases (MMPs) not only as simple effectors of ECM degradation but also as regulators of active signal-inducers for the initiation of endochondral ossification. The daunting task of elucidating their specific role during endochondral ossification has been facilitated by the development of mice deficient for various members of this family. Here, we discuss the ECM and its remodeling as one level of molecular regulation for the process of endochondral ossification, with special attention to the MMPs.

Dystroglycan in skin and cutaneous cells: beta-subunit is shed from the cell surface

In skin, hemidesmosomal protein complexes attach the epidermis to the dermis and are critical for stable connection of the basal epithelial cell cytoskeleton with the basement membrane (BM). In muscle, a similar supramolecular aggregate, the dystrophin glycoprotein complex links the inside of muscle cells with the BM. A component of the muscle complex, dystroglycan (DG), also occurs in epithelia. In this study, we characterized the expression and biochemical properties of authentic and recombinant DG in human skin and cutaneous cells in vitro. We show that DG is present at the epidermal BM zone, and it is produced by both keratinocytes and fibroblasts in vitro. The biosynthetic precursor is efficiently processed to the alpha- and beta-DG subunits; and, in addition, a distinct extracellular segment of the transmembranous beta-subunit is shed from the cell surface by metalloproteinases. Shedding of the beta-subunit releases the alpha-subunit from the DG complex on the cell surface into the extracellular space. The shedding is enhanced by IL-1beta and phorbol esters, and inhibited by metalloproteinase inhibitors. Deficiency of perlecan, a major ligand of alpha-DG, enhanced shedding suggesting that lack of a binding partner destabilizes the epithelial DG complex and makes it accessible to proteolytic processing.

Osteoblasts and osteocytes express MMP2 and -8 and TIMP1, -2, and -3 along with extracellular matrix molecules during appositional bone formation

Our previous studies suggested that a part of bone extracellular matrix (ECM) molecules are degraded and remodeled during embryonic bone formation. In contrast, little is known about ECM remodeling in postnatal appositional bone formation. The present study was designed to investigate expression of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) during experimentally initiated appositional bone formation in rats. Expressions of ECM molecules, MMPs, and TIMPs were examined using in situ hybridization. Osteoblasts and osteocytes expressed MMP2 and -8, TIMP1, -2, and -3, as well as type I collagen, osteopontin, and osteocalcin in the course of the appositional bone formation, while they showed few transcripts of MMP13. The results indicated that while osteoblasts and osteocytes in the apposed bone produce ECM molecules, they degrade ECM molecules with MMPs and regulate the degradation by inhibiting the activity of MMPs using TIMPs. Osteoblasts and osteocytes may reorganize the ECM composition to mature the bone matrix in appositional bone formation.

Molecular fingerprinting of TGFß-treated embryonic maxillary mesenchymal cells

The transforming growth factor-beta (TGF(beta)) family represents a class of signaling molecules that plays a central role in normal embryonic development, specifically in development of the craniofacial region. Members of this family are vital to development of the secondary palate where they regulate maxillary and palate mesenchymal cell proliferation and extracellular matrix synthesis. The function of this growth factor family is particularly critical in that perturbation of either process results in a cleft of the palate. While the cellular and phenotypic effects of TGF(beta) on embryonic craniofacial tissue have been extensively cataloged, the specific genes that function as downstream mediators of TGF(beta) in maxillary/palatal development are poorly defined. Gene expression arrays offer the ability to conduct a rapid, simultaneous assessment of hundreds to thousands of differentially expressed genes in a single study. Inasmuch as the downstream sequelae of TGF(beta) action are only partially defined, a complementary DNA (cDNA) expression array technology (Clontech's Atlas Mouse cDNA Expression Arrays), was utilized to delineate a profile of differentially expressed genes from TGF(beta)-treated primary cultures of murine embryonic maxillary mesenchymal cells. Hybridization of a membrane-based cDNA array (1178 genes) was performed with 32P-labeled cDNA probes synthesized from RNA isolated from either TGF(beta)-treated or vehicle-treated embryonic maxillary mesenchymal cells. Resultant phosphorimages were subject to AtlasImage analysis in order to determine differences in gene expression between control and TGF(beta)-treated maxillary mesenchymal cells. Of the 1178 arrayed genes, 552 (47%) demonstrated detectable levels of expression. Steady state levels of 22 genes were up-regulated, while those of 8 other genes were down-regulated, by a factor of twofold or greater in response to TGF(beta). Affected genes could be grouped into three general functional categories: transcription factors and general DNA-binding proteins; growth factors/signaling molecules; and extracellular matrix and related proteins. The extent of hybridization of each gene was evaluated by comparison with the abundant, constitutively expressed mRNAs: ubiquitin, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), ornithine decarboxylase (ODC), cytoplasmic beta-actin and 40S ribosomal protein. No detectable changes were observed in the expression levels of these genes in-response to TGF(beta) treatment. Gene expression profiling results were verified by Real-Time quantitative polymerase chain reaction. Utilization of cDNA microarray technology has enabled us to delineate a preliminary transcriptional map of TGF(beta) responsiveness in embryonic maxillary mesenchymal cells. The profile of differentially expressed genes offers revealing insights into potential molecular regulatory mechanisms employed by TGF(beta) in orchestrating craniofacial ontogeny.

Molecular control of epithelial-mesenchymal interactions during hair follicle cycling

Epithelial-mesenchymal interactions play pivotal roles in the morphogenesis of many organs and various types of appendages. During hair follicle development, extensive interactions between two embryologically different hair follicle compartments (epidermal keratinocytes and dermal papilla fibroblasts) lead to the formation of the hair shaft-producing mini-organ that shows cyclic activity during postnatal life with periods of active growth, involution and resting. During the hair cycle, the epithelium and the mesenchyme are regulated by a distinct set of molecular signals that are unique for every distinct phase of the hair cycle. In telogen hair follicles, epithelial-mesenchymal interactions are characterized by a predominance of inhibitory signals that retain the hair follicle in a quiescent state. During anagen, a large variety of growth stimulatory pathways are activated in the epithelium and in the mesenchyme, the coordination of which are essential for proper hair fiber formation. During catagen, the termination of anagen-specific signaling interactions between the epithelium and the mesenchyme leads to apoptosis in the hair follicle epithelium, while activation of selected signaling pathways promotes the transition of the dermal papilla into a quiescent state. The signaling exchange between the follicular epithelium and the mesenchyme is modulated by proteoglycans, such as versican, which may significantly enhance or reduce the biological activities of secreted growth stimulators. However, additional research will be required to bridge the gap between our current understanding of mechanisms underlying epithelial-mesenchymal interactions in hair follicles and the potential clinical application of growth modulators involved in those interactions. Further progress in this area of research will hopefully lead to the development of new drugs for the treatment of hair growth disorders.

Matrix metalloproteinases in tumor progression: focus on basal and squamous cell skin cancer

Many normal biological processes, such as reproduction, fetal development and wound healing, are critically dependent on controlled degradation of extracellular matrix (ECM) macromolecules. However, excessive degradation of matrix components occurs in pathologic tissue destruction, e.g. in atherosclerosis, rheumatoid arthritis, and cancer. Matrix metalloproteinases (MMPs) are degradative enzymes that play an important role in all aspects of tumor progression by enhancing tumor-induced angiogenesis and destroying local tissue architecture and basement membranes to allow tumor invasion and metastasis. Efficient breakdown of the ECM surrounding invasive cancer islands involves interplay between tumor cells, stromal cells, and inflammatory cells, all of which express a distinct set of MMPs. Besides the classical role of MMPs in degradation of ECM, MMPs may also indirectly influence the tumor microenvironment through the release of growth factors, cryptic sites or angiogenic factors, or through the generation of matrix fragments that inhibit tumor cell proliferation, migration and angiogenesis. This makes the contribution of MMPs to tumorigenesis much more complex than initially thought. Currently, a number of clinical studies have focused on testing MMP inhibitors as potential antineoplastic agents. In this review we discuss the present role of MMPs in the development and progression of cancer, focusing on non-melanoma skin cancers basal (BCC) and squamous (SCC) cell carcinoma, and the possible influence of MMPs in their differences.

A novel function for tissue inhibitor of metalloproteinases-3 (TIMP3): inhibition of angiogenesis by blockage of VEGF binding to VEGF receptor-2

Tissue inhibitor of metalloproteinases-3 (TIMP3) is one of four members of a family of proteins that were originally classified according to their ability to inhibit matrix metalloproteinases (MMP). TIMP3, which encodes a potent angiogenesis inhibitor, is mutated in Sorsby fundus dystrophy, a macular degenerative disease with submacular choroidal neovascularization. In this study we demonstrate the ability of TIMP3 to inhibit vascular endothelial factor (VEGF)-mediated angiogenesis and identify the potential mechanism by which this occurs: TIMP3 blocks the binding of VEGF to VEGF receptor-2 and inhibits downstream signaling and angiogenesis. This property seems to be independent of its MMP-inhibitory activity, indicating a new function for this molecule.

Overexpression of tissue inhibitor of metalloproteinases-3 in intestinal and cutaneous lesions of graft-versus-host disease

Matrix metalloproteinases (MMPs) have been implicated in the pathobiology of various T-cell-mediated inflammatory disorders of the intestine and skin. Their synthetic inhibitor has been shown to prevent lethal acute graft-versus-host disease in animal models. We intended to determine the expression of MMPs 1, 3, 7, 9, 10, 12, and 19 and tissue inhibitors of metalloproteinases (TIMPs) 1 and 3 in intestinal and cutaneous lesions of patients suffering from graft-versus-host disease after bone marrow transplantation. In situ hybridizations for MMPs 1, 3, 7, 10, and 12 as well as TIMPs 1 and 3 were performed using (35)S-labeled cRNA probes on intestinal (n = 13) and cutaneous specimens (n = 9) from patients with graft-versus-host disease. Immunohistochemical stainings were carried out to localize MMP-9, MMP-19, TIMP-3, and TGF-beta1 proteins, and TUNEL staining, to detect apoptotic cells. TIMP-3 mRNA and protein were detected in cutaneous lesions in areas with vacuolar degeneration of the basal epidermal layer in all skin samples, and they colocalized with apoptotic keratinocytes and partly with staining for TGF-beta. None of the MMPs examined were overexpressed in skin lesions. Signals for MMP-1 and MMP-3 mRNA was found in 10/13 and 5/13 intestinal biopsies, respectively. In the gut, MMP-19-positive epithelial cells, particularly in the crypts, were found in 10/13 samples. Expression of MMPs 7, 9, 10, and 12 was absent or very low. TIMPs 1 and 3 were expressed by stromal cells in 12/13 and 10/13 gut samples, respectively. Whereas TIMP-1 was expressed particularly by subepithelial cells where epithelium had shed away, TIMP-3 was detected in deeper areas. We conclude that MMPs are differentially regulated in the skin and gut lesions of graft-versus-host disease. In agreement with previous data on cancer cells, TIMP-3, induced by TGF-beta1, may contribute to the apoptosis of keratinocytes in cutaneous graft-versus-host disease lesions, leading to typical histopathological changes. We also conclude that MMPs play a less important role as effector molecules in intestinal graft-versus-host disease than in celiac or inflammatory bowel disease.

Differentiative potential of human metanephric mesenchymal cells

OBJECTIVE

To evaluate the ability of mesenchymal cells derived from nonhematopoietic organs to form blood and other tissues in vitro and in vivo.

MATERIALS AND METHODS

Because of its mesodermic derivation, human fetal kidney was used as a source of mesenchymal cells. Two populations of kidney cells were studied at a nonclonal level: a crude preparation, and an adherent fraction that was derived from the first by propagation in vitro (MNMC). Both populations were transplanted into sheep fetuses and analyzed at intervals for the presence of human cells in different organs by flow cytometry, PCR, immunohistochemistry, and in situ hybridization. Secondary transplantation studies were performed using human hematopoietic cells obtained from the bone marrow (BM) of primary recipients.

RESULTS

MNMC were Thy-1(+), CD51(+), CD44(+), CD45(-), and vimentin(+), a phenotype consistent with that of metanephric mesenchyme. The crude population displayed the same phenotype but was contaminated with 0.4% CD34(+)CD45(+) cells. Cells with hepatocyte-like morphology and phenotype were obtained from the MNMC after culture in specific inducing media. After transplantation, both populations of cells produced multilineage hematopoietic engraftment and gave rise to CD34(+) cells. Successful hematopoietic engraftment in secondary recipients demonstrated the generation of long-term engrafting hematopoietic stem cells from MNMC. PCR analysis confirmed human hematopoietic engraftment and revealed that human cells were also present within other organs. Liver sections of transplanted animals contained human albumin-producing hepatocyte-like cells.

CONCLUSION

A human metanephric mesenchymal cell population simultaneously gave rise to human blood and liver-like cells, suggesting that mesenchymal cells may represent a broad population of putative stem cells in multiple adult organs.

Transmembrane collagen XVII, an epithelial adhesion protein, is shed from the cell surface by ADAMs

Collagen XVII, a type II transmembrane protein and epithelial adhesion molecule, can be proteolytically shed from the cell surface to generate a soluble collagen. Here we investigated the release of the ectodomain and identified the enzymes involved. After surface biotinylation of keratinocytes, the ectodomain was detectable in the medium within minutes and remained stable for >48 h. Shedding was enhanced by phorbol esters and inhibited by metalloprotease inhibitors, including hydroxamates and TIMP-3, but not by inhibitors of other protease classes or by TIMP-2. This profile implicated MMPs or ADAMs as candidate sheddases. MMP-2, MMP-9 and MT1-MMP were excluded, but TACE, ADAM-10 and ADAM-9 were shown to be expressed in keratinocytes and to be actively involved. Transfection with cDNAs for the three ADAMs resulted in increased shedding and, vice versa, in TACE-deficient cells shedding was significantly reduced, indicating that transmembrane collagen XVII represents a novel class of substrates for ADAMs. Functionally, release of the ectodomain of collagen XVII from the cell surface was associated with altered keratinocyte motility in vitro.

Antitumor activity and bystander effect of adenovirally delivered tissue inhibitor of metalloproteinases-3

We have studied the effect of a newly identified tumor suppressor tissue inhibitor of metalloproteinases- 3 (TIMP-3) on the growth of human melanoma and squamous-cell carcinoma (SCC). Adenoviral delivery of the TIMP-3 gene to human melanoma (A2058) and SCC (UT-SCC-7) cells ex vivo inhibited tumorigenesis after subcutaneous (s.c.) injection of the infected cells into SCID/SCID mice. Three daily consecutive intratumoral injections of 1.4x10(9) plaque-forming units (pfu) of TIMP-3 adenovirus (RAdTIMP-3) inhibited the growth of preestablished melanoma and SCC xenografts in SCID/SCID mice, whereas growth of control virus-injected tumors was not affected. The antitumor effect of RAdTIMP-3 was obtained with in vivo adenoviral transduction efficiency of 8-10%, and it was more potent than that of adenovirally delivered p53. Adenovirusmediated expression of TIMP-3 potently reduced gelatinolytic activity, increased the number of apoptotic cells, and inhibited vascularization of melanomas. Escalation of the adenoviral dose to three rounds of three daily consecutive injections with 1.4x10(9) pfu of RAdTIMP-3 every 6 days entirely inhibited growth of injected melanomas for 32 days. Mixing RAdTIMP-3-infected A2058 cells with uninfected cells in 1:1 ratio in culture resulted in death of all cells in 96 hours. Adenovirally delivered TIMP-3 was also expressed by A2058 cells in soluble form into the culture medium, where it exerted a cytotoxic effect on uninfected A2058 cell cultures after relocating to the cell layer. These results identify TIMP-3 as a novel type of secreted tumor suppressor, which has antiinvasive, antiangiogenic, and proapoptotic effects in vivo, and which displays a potent bystander effect validating further exploration of its applicability in human cancer gene therapy.

Stromelysin-1 activation correlates with invasiveness in squamous cell carcinoma

The expression of selected metalloproteinases and tissue inhibitors of metalloproteinases (TIMP) was examined in three squamous cell carcinoma (SCC) cell lines (FaDu, SiHa, A431) and a keratinocyte cell line (HaCaT) to determine which metalloproteinases function in SCC invasiveness. A Matrigel invasion assay was used to assess invasiveness of the cell lines. Only the FaDu cell line showed invasiveness in this assay, and invasion of Matrigel by FaDu cells was inhibited by treatment with the metalloproteinase inhibitor, batimastat. No correlation was found between mRNA expression for matrilysin, stromelysins 1-3, TIMP-1, or TIMP-3 and secretion of these proteins, indicating that the extracellular activity of these molecules is regulated post-transcriptionally. The SCC cell lines differed from the HaCaT line in that matrilysin and TIMP-1 proteins were detected in conditioned medium from all SCC cell lines, but not in medium from HaCaT cells. Only the invasive cell line, FaDu, released active stromelysin-1 into the culture medium. These results indicate that while matrilysin contributes to the invasive phenotype, activation of stromelysin-1 is a key regulatory step for invasiveness in SCC cells.

Topical synthetic inhibitor of matrix metalloproteinases delays epidermal regeneration of human wounds

Matrix metalloproteinases (MMPs) degrade extracellular proteins during epithelialization of wounds. To evaluate the biological significance of MMPs in epidermal healing, the synthetic broad-spectrum MMP inhibitor GM 6001 (also called Galardin and Ilomastat) was applied topically to standardized human wounds. GM 6001 (10 microg/microl) or vehicle alone was applied every second day onto 4 de-roofed 6 mm suction blister wounds on the volar forearm of healthy male volunteers for 12 days. GM 6001 delayed healing by 2-4 days as assessed macroscopically and microscopically. In situ hybridization or immunohistochemistry showed that MMP-1 (interstitial collagenase) was present in and MMP-2 (gelatinase A) close to laterally migrating keratinocytes whereas MMP-9 (gelatinase B) was seen during maturation of new epidermis. MMP-1 was undetectable in blister roofs (normal epidermis) and found in low levels in normal skin. Total MMP-1 activities increased about 100-fold in wounds, independent of treatment, compared to normal skin as analyzed by specific ELISA-based activity assay. By gelatin zymography, MMP-2, but not MMP-9, was detected in blister roofs and wound healing was associated with increased active MMP-2 and latent MMP-9 levels. GM 6001 prevented activation of MMP-2 and increased latent MMP-9 levels. GM 6001 delayed re-appearance of laminin-5, the synthesis of which correlated with epidermal regeneration. Restoration of stratum corneum, measured indirectly by transepidermal water loss, was also impaired (P<0.05) in the GM 6001 group. In conclusion, pharmacological MMP inhibition delayed epidermal regeneration in vivo, suggesting that MMPs are required to restore epidermis after epidermal ablation in humans.

Upregulation and differential expression of matrilysin (MMP-7) and metalloelastase (MMP-12) and their inhibitors TIMP-1 and TIMP-3 in Barrett's oesophageal adenocarcinoma

Oesophageal adenocarcinoma is believed to arise from metaplastic mucosa in the distal oesophagus, a condition also known as Barrett's oesophagus (BE). BE develops as a result of injury caused by refluxing gastric and duodenal contents and is associated with increased risk of malignant transformation. Matrix metalloproteinases (MMPs) have been implicated in all aspects of tumour progression; tumour growth, basement membrane degradation, invasion and metastatic spread. Using in situ hybridization, we investigated the expression patterns of collagenases-1 and -3, stromelysin-2, matrilysin, metalloelastase and TIMPs-1 and -3 in BE, adenocarcinoma and lymph-node metastases. Matrilysin was expressed abundantly in 12/15 tumours and in 4/6 lymph-node metastases and its expression correlated with the histological aggressiveness of tumour. Matrilysin and metalloelastase were upregulated already in BE. Stromelysin-2 and collagenase-3 expression was detected only in a few tumours. Collagenase-1 was expressed by cancer and stromal cells in 9/15 tumours. Tumour-infiltrating macrophages expressed metalloelastase in 13/15 cancers. TIMPs-1 and -3 were expressed in 12/15 and 11/15 tumours, respectively. Laminin-5 and tenascin were abundantly expressed at the invasive front of poorly differentiated tumours, but not in BE. Our results indicate that matrilysin is the principal MMP expressed by tumour cells in oesophageal adenocarcinoma, and further studies are needed to investigate whether matrilysin or tenascin-C could be used as a predictive marker for progression of BE to cancer.

Tissue inhibitor of metalloproteinase-3 is a basement membrane-associated protein that is significantly decreased in human colorectal cancer

PURPOSE

The balance between local levels of matrix metalloproteinases and tissue inhibitor of metalloproteinases is believed to play a key role in tumor invasion and metastases. Because tissue inhibitor of metalloproteinase-3 suppresses tumorigenicity and tumor invasion in vitro, the aim of this study was to determine its expression in human colorectal cancer.

METHODS

Thirty-nine human colorectal cancer specimens, three adenomas, and matched normal adjacent mucosa from 39 colorectal cancer patients were analyzed. Tissue inhibitor of metalloproteinase-3 ribonucleic acid and protein expression were analyzed by Northern blot hybridization and Western blot analysis, respectively. The cellular localizations of tissue inhibitor of metalloproteinase-3 ribonucleic acid and protein were determined by in situ hybridization and immunolocalization.

RESULTS

Tissue inhibitor of metalloproteinase-3 ribonucleic acid expression was increased in colorectal cancer compared with paired normal mucosa. In contrast, tissue inhibitor of metalloproteinase-3 protein level was higher in normal mucosa than in the corresponding colorectal cancer. In addition, tissue inhibitor of metalloproteinase-3 protein levels progressively decreased with advancing colorectal cancer stages. Tissue inhibitor of metalloproteinase-3 protein tumor to normal mucosa ratio was 0.74 +/- 0.12, 0.51 +/- 0.18, 0.48 +/- 0.12, and 0.45 +/- 0.2 for Dukes A (n = 8), B (n = 9), C (n = 9), and D (n = 13) stages, respectively. Both tissue inhibitor of metalloproteinase-3 messenger ribonucleic acid and protein were located predominantly within spindle-shaped and round stromal cells. Furthermore, in colonic epithelium, tissue inhibitor of metalloproteinase-3 and type IV collagen protein were similarly concentrated in the basal region.

CONCLUSIONS

These data provide the first detailed description of the cellular expression of tissue inhibitor of metalloproteinase-3 in colorectal cancer and identify it as a basement membrane-associated protein. This is an important observation, because the presence of tissue inhibitor of metalloproteinase-3 protein near the basement membrane supports its role in preventing proteolytic degradation, angiogenesis, and apoptosis.

Upregulation and differential expression of matrilysin (MMP-7) and metalloelastase (MMP-12) and their inhibitors TIMP-1 and TIMP-3 in Barrett's oesophageal adenocarcinoma

Oesophageal adenocarcinoma is believed to arise from metaplastic mucosa in the distal oesophagus, a condition also known as Barrett's oesophagus (BE). BE develops as a result of injury caused by refluxing gastric and duodenal contents and is associated with increased risk of malignant transformation. Matrix metalloproteinases (MMPs) have been implicated in all aspects of tumour progression; tumour growth, basement membrane degradation, invasion and metastatic spread. Using in situ hybridization, we investigated the expression patterns of collagenases-1 and -3, stromelysin-2, matrilysin, metalloelastase and TIMPs-1 and -3 in BE, adenocarcinoma and lymph-node metastases. Matrilysin was expressed abundantly in 12/15 tumours and in 4/6 lymph-node metastases and its expression correlated with the histological aggressiveness of tumour. Matrilysin and metalloelastase were upregulated already in BE. Stromelysin-2 and collagenase-3 expression was detected only in a few tumours. Collagenase-1 was expressed by cancer and stromal cells in 9/15 tumours. Tumour-infiltrating macrophages expressed metalloelastase in 13/15 cancers. TIMPs-1 and -3 were expressed in 12/15 and 11/15 tumours, respectively. Laminin-5 and tenascin were abundantly expressed at the invasive front of poorly differentiated tumours, but not in BE. Our results indicate that matrilysin is the principal MMP expressed by tumour cells in oesophageal adenocarcinoma, and further studies are needed to investigate whether matrilysin or tenascin-C could be used as a predictive marker for progression of BE to cancer.

Metalloelastase (MMP-12) and 92-kDa gelatinase (MMP-9) as well as their inhibitors, TIMP-1 and -3, are expressed in psoriatic lesions

In skin biology, matrix metalloproteinases (MMPs) have been implicated in inflammatory matrix remodeling, neovascularization, wound healing and malignant transformation. Psoriasis is histologically characterized by keratinocyte hyperproliferation, infiltration of inflammatory cells, neoangiogenesis and production of cytokines, such as TNF-alpha, IL-1beta, TGF-alpha, and IFN-gamma, also capable of regulating MMP transcription. To investigate the role of stromelysins-1 and -2, matrilysin, metalloelastase, collagenases-1 and -3 and 92-kDa gelatinase as well as their inhibitors, TIMPs-1 and -3, in psoriasis, we performed in situ hybridization using 35S-labeled cRNA probes on 29 psoriatic lesions and 9 samples of normal looking skin from psoriatic patients. Metalloelastase mRNA was detected in 21/27 samples in macrophages that had migrated into the epidermis or in the inflammatory infiltrates of the superficial dermis. A quantity of 92-kDa gelatinase was found in macrophages and neutrophils (25/27). Stromelysin-1 mRNA was detected in basal keratinocytes in 4/21 lesions. Intracellular laminin-5 immunosignal in basal keratinocytes of the same samples, suggested that stromelysin-1 might participate in remodeling of the basement membrane zone. No signal for stromelysin-2 or collagenase-3 was found and only sweat glands were positive for matrilysin. TIMP-1 was more abundantly expressed than TIMP-3 in the inflammatory infiltrates and endothelial cells of dermal papillae (22/29). TIMP-3 was expressed perivascularly in 9/16 samples. Our results suggest that overexpression of the investigated MMPs by keratinocytes is not associated with psoriasis. However, macrophages express MMPs in psoriatic skin. Also TIMPs, particularly TIMP-1, were abundantly expressed, suggesting that mere MMP overexpression is unlikely to contribute to psoriatic tissue changes.

Controls of hair follicle cycling

Nearly 50 years ago, Chase published a review of hair cycling in which he detailed hair growth in the mouse and integrated hair biology with the biology of his day. In this review we have used Chase as our model and tried to put the adult hair follicle growth cycle in perspective. We have tried to sketch the adult hair follicle cycle, as we know it today and what needs to be known. Above all, we hope that this work will serve as an introduction to basic biologists who are looking for a defined biological system that illustrates many of the challenges of modern biology: cell differentiation, epithelial-mesenchymal interactions, stem cell biology, pattern formation, apoptosis, cell and organ growth cycles, and pigmentation. The most important theme in studying the cycling hair follicle is that the follicle is a regenerating system. By traversing the phases of the cycle (growth, regression, resting, shedding, then growth again), the follicle demonstrates the unusual ability to completely regenerate itself. The basis for this regeneration rests in the unique follicular epithelial and mesenchymal components and their interactions. Recently, some of the molecular signals making up these interactions have been defined. They involve gene families also found in other regenerating systems such as fibroblast growth factor, transforming growth factor-beta, Wnt pathway, Sonic hedgehog, neurotrophins, and homeobox. For the immediate future, our challenge is to define the molecular basis for hair follicle growth control, to regenerate a mature hair follicle in vitro from defined populations, and to offer real solutions to our patients' problems.

Timp-1 is important for epithelial proliferation and branching morphogenesis during mouse mammary development

The dynamic process of mammary ductal morphogenesis depends on regulated epithelial proliferation and extracellular matrix (ECM) turnover. Epithelial cell-matrix contact closely dictates epithelial proliferation, differentiation, and survival. Despite the fact that tissue inhibitors of metalloproteinases (Timps) regulate ECM turnover, their function in mammary morphogenesis is unknown. We have delineated the spatiotemporal expression of all Timps (Timp-1 to Timp-4) during discrete phases of murine mammary development. Timp mRNAs were abundant in mammary tissue, each displaying differential expression patterns with predominant localization in luminal epithelial cells. Timp-1 mRNA was unique in that its expression was limited to the stage at which epithelial proliferation was high. To assess whether Timp-1 promotes or inhibits epithelial cell proliferation we manipulated mammary Timp-1 levels, genetically and biochemically. Down-regulation of epithelial-derived Timp-1 in transgenic mice, by mouse mammary tumor virus promoter-directed Timp-1 antisense RNA expression, led to augmented ductal expansion and increased number of ducts (P < 0.004). In these transgenics the integrity of basement membrane surrounding epithelial ducts, as visualized by laminin-specific immunostaining, was breached. In contrast to these mice, ductal expansion was markedly attenuated in the proximity of implanted recombinant Timp-1-releasing pellets (rTIMP-1), without an increase in basement membrane deposition around migrating terminal end buds. Epithelial proliferation and apoptosis were measured to determine the basis of altered ductal expansion. Luminal epithelial proliferation was increased by 55% (P < 0.02) in Timp-1-reduced transgenic mammary tissue and, conversely, decreased by 38% (P < 0.02) in terminal end buds by implanted rTIMP-1. Epithelial apoptosis was minimal and remained unaffected by Timp-1 manipulations. We conclude that Timps have an integral function in mammary morphogenesis and that Timp-1 regulates mammary epithelial proliferation in vivo, at least in part by maintaining basement membrane integrity.

Differential expression of tissue inhibitors of metalloproteinases (TIMP-1, -2, -3, and -4) in normal and aberrant wound healing

Wound healing is characterized by hemostasis, re-epithelialization, granulation tissue formation, and remodeling of the extracellular matrix. Matrix metalloproteinases and their specific inhibitors, TIMPs, contribute to these events. We investigated a total of 47 samples of normally healing wounds, chronic venous ulcers, ulcerative vasculitis, and suction blisters using immunohistochemistry and in situ hybridization, to clarify the role of TIMPs in normal and aberrant wound repair. Expression of TIMP-1 and -3 mRNAs was found in proliferating keratinocytes in 3- to 5-day-old normally healing wounds, whereas no epidermal expression was detected in chronic ulcers. However, TIMP-3 protein was found in the proliferating epidermis in 20 of 24 samples representing both full-thickness acute and chronic wounds. TIMP-1 and TIMP-3 also were abundantly expressed by spindle-shaped, fibroblast-like, and plump, macrophage-like stromal cells, as well as by endothelial cells. In normally healing wounds, TIMP-2 protein localized under the migrating epithelial tip and to the stromal tissue under the eschar more frequently than in chronic ulcers. Occasional staining for TIMP-4 protein was detected in stromal cells of chronic ulcers near blood vessels. Our results indicate that TIMP-1 and TIMP-3 may be involved both in the regeneration of the epidermis by stabilizing the basement membrane zone and in the regulation of stromal remodeling and angiogenesis of the wound bed. Lack of TIMP-2 near the migrating epithelial wound edges might contribute to uncontrolled activity of MMP-2 in chronic ulcers. We conclude also that TIMPs are temporally and spatially tightly regulated and that the imbalance between metalloproteinases and TIMPs-1, -2, and -3 may lead to delayed wound healing.

Sorsby's fundus dystrophy: what does TIMP3 tell us about general mechanisms underlying macular degeneration?

INTRODUCTION: Mutations in tissue inhibitor of metalloproteinases-3 (TIMP3) gene result in the rare autosomal dominant disease Sorsby's fundus dystrophy (SFD), which shows striking similarities to age-related macular degeneration (ARMD). METHODS: Current research is reviewed and suggests that these mutations result in the accumulation of TIMP3 in Bruch's membrane resulting in decreased turnover of the extracellular matrix and consequent thickening of Bruch's membrane. DNA analysis of ARMD patients has failed to show any significant mutations in the coding-regions of TIMP3. However, this should not be taken to imply that TIMP3 is not affected in the disease, as another possibility is that levels of TIMP3 might be elevated by other mechanisms. CONCLUSION: The finding that TIMP3 levels are elevated in simplex retinitis pigmentosa in the absence of coding mutations begs for a revaluation of its role in other retinal conditions such as ARMD.

Expression of collagenases-1 and -3 and their inhibitors TIMP-1 and -3 correlates with the level of invasion in malignant melanomas

Since proteolysis of the dermal collagenous matrix and basement membranes is required for local invasive growth and early metastasis formation of cutaneous melanomas, we have analysed the activities/expression levels of certain metalloproteinases in melanomas and cultured melanoma cells by in situ hybridization and Northern analysis. In addition to collagenases-1 and -3 that have been implicated in invasive growth behaviour of various malignant tumours, we analysed the levels of 72-kDa gelatinase and its activators MT1-MMP and TIMP-2 in cultured melanoma cells. The lesions examined included three cases of lentigo maligna and 28 cases of Clark grade I-V melanomas. The premalignant as well as the grade I tumours were consistently negative for collagenase-1 and -3 and TIMP-1 and -3. The collagenases were predominantly expressed in the cancer cells of Clark grade III and IV tumours. TIMP-1 and -3 were abundantly expressed in the cancer and/or stromal cells of grade III and IV melanomas, while TIMP-2 protein was detected also in melanomas representing lower invasive potential. Northern analysis of seven melanoma cell lines showed that the expression of collagenase-1 and TIMPs-1 and -3 was associated with 72-kDa gelatinase positivity. All melanoma cell lines were positive for MT1-MMP and TIMP-2 mRNAs. Our results suggest that overexpression of collagenases-1 and -3 and TIMPs-1 and -3 is induced during melanoma progression. Expression of TIMPs may reflect host response to tumour invasion in an effort to control MMP activity and preserve extracellular matrix integrity.

Matrix metalloproteinases and their inhibitors in tumour growth and invasion

Controlled degradation of the extracellular matrix (ECM) is crucial for the growth, invasive capacity, metastasis and angiogenesis of tumours. Matrix metalloproteinases (MMPs), a family of zinc-dependent neutral endopeptidases that are collectively capable of degrading essentially all ECM components, apparently play an important role in all of these aspects of tumour development. In addition, there is recent evidence that MMPs are also important for tumour cell survival. At present, therapeutic intervention on tumour growth and invasion based on the inhibition of MMP activity is under intensive investigation, and several MMP inhibitors are already being used on malignant tumours of various organs in clinical trials. In this review we discuss the role of MMPs and their inhibitors in tumour invasion as a basis for prognostic purposes and for targeted therapeutic intervention in cancer.

Matrix metalloproteinases in skin

Matrix metalloproteinases (MMPs) are a family of zinc-dependent endopeptidases collectively capable of degrading essentially all extracellular matrix components. These enzymes can be produced by several different types of cells in skin such as fibroblasts, keratinocytes, macrophages, endothelial cells, mast cells, and eosinophils and their activity can be specifically inhibited by TIMPs (tissue inhibitors of metalloproteinases), which bind to active MMPs with 1:1 stoichiometry. In general, MMPs are not constitutively expressed in skin but are induced temporarily in response to exogenous signals such as various cytokines, growth factors, cell matrix interactions and altered cell-cell contacts. At present, more evidence is accumulating that MMPs play an important role in proteolytic remodeling of extracellular matrix in various physiologic situations, including developmental tissue morphogenesis, tissue repair, and angiogenesis. On the other hand, MMPs play an important pathogenetic role in excessive breakdown of connective tissue components, e.g. in rheumatoid arthritis, osteoarthritis, chronic ulcers, dermal photoageing, and periodontitis, as well as in tumor cell invasion and metastasis. In this review we discuss the role of MMPs and TIMPs in human skin based on new observations on the regulation of the expression of MMPs, on their substrate specificity, and MMP expression in physiologic and pathologic conditions of skin involving matrix remodeling. Furthermore, therapeutic modalities based on regulating MMP activity will be reviewed.