Xenopus ADAMTS1 negatively modulates FGF signaling independent of its metalloprotease activity

Regulation of gene expression downstream of a novel Fgf/Erk pathway during Xenopus development

Activation of Map kinase/Erk signalling downstream of fibroblast growth factor (Fgf) tyrosine kinase receptors regulates gene expression required for mesoderm induction and patterning of the anteroposterior axis during Xenopus development. We have proposed that a subset of Fgf target genes are activated in the embyo in response to inhibition of a transcriptional repressor. Here we investigate the hypothesis that Cic (Capicua), which was originally identified as a transcriptional repressor negatively regulated by receptor tyrosine kinase/Erk signalling in Drosophila, is involved in regulating Fgf target gene expression in Xenopus. We characterise Xenopus Cic and show that it is widely expressed in the embryo. Fgf overexpression or ectodermal wounding, both of which potently activate Erk, reduce Cic protein levels in embryonic cells. In keeping with our hypothesis, we show that Cic knockdown and Fgf overexpression have overlapping effects on embryo development and gene expression. Transcriptomic analysis identifies a cohort of genes that are up-regulated by Fgf overexpression and Cic knockdown. We investigate two of these genes as putative targets of the proposed Fgf/Erk/Cic axis: fos and rasl11b, which encode a leucine zipper transcription factor and a ras family GTPase, respectively. We identify Cic consensus binding sites in a highly conserved region of intron 1 in the fos gene and Cic sites in the upstream regions of several other Fgf/Cic co-regulated genes, including rasl11b. We show that expression of fos and rasl11b is blocked in the early mesoderm when Fgf and Erk signalling is inhibited. In addition, we show that fos and rasl11b expression is associated with the Fgf independent activation of Erk at the site of ectodermal wounding. Our data support a role for a Fgf/Erk/Cic axis in regulating a subset of Fgf target genes during gastrulation and is suggestive that Erk signalling is involved in regulating Cic target genes at the site of ectodermal wounding.

ADAMTS1 induces epithelial-mesenchymal transition pathway in non-small cell lung cancer by regulating TGF-β

Non-small cell lung cancer (NSCLC) accounts for approximately 80% of all lung cancers. Identifying key molecular targets related to the initiation, development, and metastasis of lung cancer is important for its diagnosis and target therapy. The ADAMTS families of multidomain extracellular protease enzymes have been reported to be involved in many physiological processes. In this study, we found that ADAMTS1 was highly expressed in NSCLC tissues, which promoted cell proliferation, migration, invasion, and epithelial to mesenchymal transition (EMT) of NSCLC cells. In the NSCLC tumor metastasis model involving nude mice, overexpression of ADAMTS1 promoted EMT and lung metastasis of tumor cells. Moreover, ADAMTS1 positively regulated TGF-β expression, and TGF-β was highly expressed in NSCLC tumor tissues. si-TGF-β or inhibition of TGF-β expression through the short peptide KTFR on ADAMTS1 protein could reverse the oncogenic effects of ADAMTS1 on lung cancer cells. Taken together, ADAMTS1 functioned as an oncogene in NSCLC cells by promoting TGF-β expression, indicating that ADAMTS1 has important regulatory roles in the progression of NSCLC.

Tissue-specific expression of carbohydrate sulfotransferases drives keratan sulfate biosynthesis in the notochord and otic vesicles of Xenopus embryos

Keratan sulfate (KS) is a glycosaminoglycan that is enriched in vertebrate cornea, cartilage, and brain. During embryonic development, highly sulfated KS (HSKS) is first detected in the developing notochord and then in otic vesicles; therefore, HSKS has been used as a molecular marker of the notochord. However, its biosynthetic pathways and functional roles in organogenesis are little known. Here, I surveyed developmental expression patterns of genes related to HSKS biosynthesis in Xenopus embryos. Of these genes, the KS chain-synthesizing glycosyltransferase genes, beta-1,3-N-acetylglucosaminyltransferase (b3gnt7) and beta-1,4-galactosyltransferase (b4galt4), are strongly expressed in the notochord and otic vesicles, but also in other tissues. In addition, their notochord expression is gradually restricted to the posterior end at the tailbud stage. In contrast, carbohydrate sulfotransferase (Chst) genes, chst2, chst3, and chst5.1, are expressed in both notochord and otic vesicles, whereas chst1, chst4/5-like, and chst7 are confined to otic vesicles. Because the substrate for Chst1 and Chst3 is galactose, while that for others is N-acetylglucosamine, combinatorial, tissue-specific expression patterns of Chst genes should be responsible for tissue-specific HSKS enrichment in embryos. As expected, loss of function of chst1 led to loss of HSKS in otic vesicles and reduction of their size. Loss of chst3 and chst5.1 resulted in HSKS loss in the notochord. These results reveal that Chst genes are critical for HSKS biosynthesis during organogenesis. Being hygroscopic, HSKS forms “water bags” in embryos to physically maintain organ structures. In terms of evolution, in ascidian embryos, b4galt and chst-like genes are also expressed in the notochord and regulate notochord morphogenesis. Furthermore, I found that a chst-like gene is also strongly expressed in the notochord of amphioxus embryos. These conserved expression patterns of Chst genes in the notochord of chordate embryos suggest that Chst is an ancestral component of the chordate notochord.

Restoring mammary gland structures and functions with autogenous cell therapy

In somatic cell reprogramming, cells must escape the somatic cell-specific gene expression program to adopt other cell fates. Here, in vitro chemical induction with RepSox generated chemically induced mammary epithelial cells (CiMECs) with milk secreting functions from goat ear fibroblasts (GEFs). Transplanted CiMECs regenerated the normal mammary gland structure with milk-secreting functions in nude mice. Single-cell RNA sequencing revealed that during the reprogramming process, GEFs may sequentially undergo embryonic ectoderm (EE)-like and different MEC developmental states and finally achieve milk secreting functions, bypassing the pluripotent state. Mechanistically, Smad3 upregulation induced by transforming growth factor β (TGFβ) receptor 1 (TGFβR1) downregulation led to GEF reprogramming into CiMECs without other reprogramming factors. The TGFβR1-Smad3 regulatory effects will provide new insight into the TGFβ signaling pathway regulation of somatic cell reprogramming. These findings suggest an innovative strategy for autogenous cell therapy for mammary gland defects and the production of transgenic mammary gland bioreactors.

ADAMTS9, a member of the ADAMTS family, in Xenopus development

Extracellular matrix (ECM) remodeling by metalloproteinases is crucial during development. The ADAMTS (A Disintegrin and Metalloproteinase with Thrombospondin type I motifs) enzymes are secreted, multi-domain matrix-associated zinc metalloendopeptidases that have diverse roles in tissue morphogenesis and patho-physiological remodeling. The human family includes 19 members. In this study we identified the 19 members of the ADAMTS family in Xenopus laevis and Xenopus tropicalis. Gene identification and a phylogenetic study revealed strong conservation of the ADAMTS family and contributed to a better annotation of the Xenopus genomes. Expression of the entire ADAMTS family was studied from early stages to tadpole stages of Xenopus, and detailed analysis of ADAMTS9 revealed expression in many structures during organogenesis such as neural crest (NC) derivative tissues, the pronephros and the pancreas. Versican, a matrix component substrate of ADAMTS9 shows a similar expression pattern suggesting a role of ADAMTS9 in the remodeling of the ECM in these structures by degradation of versican.

The ADAMTS hyalectanase family: biological insights from diverse species

The a disintegrin-like and metalloproteinase with thrombospondin type-1 motifs (ADAMTS) family of metzincins are complex secreted proteins that have diverse functions during development. The hyalectanases (ADAMTS1, 4, 5, 8, 9, 15 and 20) are a subset of this family that have enzymatic activity against hyalectan proteoglycans, the processing of which has important implications during development. This review explores the evolution, expression and developmental functions of the ADAMTS family, focusing on the ADAMTS hyalectanases and their substrates in diverse species. This review gives an overview of how the family and their substrates evolved from non-vertebrates to mammals, the expression of the hyalectanases and substrates in different species and their functions during development, and how these functions are conserved across species.

ADAMTS proteases and cancer

ADAMTSs (A disintegrin and metalloprotease domains with thrombospondins motifs) are complex extracellular proteases that have been related to both oncogenic and tumor-protective functions. These enzymes can be secreted by cancer and stromal cells and may contribute to modify the tumor microenvironment by multiple mechanisms. Thus, ADAMTSs can cleave or interact with a wide range of extracellular matrix components or regulatory factors, and therefore affect cell adhesion, migration, proliferation and angiogenesis. The balance of protumor versus antitumor effects of ADAMTSs may depend on the nature of their substrates or interacting-partners upon secretion from the cell. Moreover, different ADAMTS genes have been found overexpressed, mutated or epigenetically silenced in tumors from different origins, suggesting the direct impact of these metalloproteases in cancer development. However, despite the important advances on the tumor biology of ADAMTSs in recent years, more mechanistic and functional studies are necessary to fully understand how these proteases can influence tumor microenvironment to potentiate cancer growth or to induce tumor regression. This review outlines current and emerging connections between ADAMTSs and cancer.

The splicing factor PQBP1 regulates mesodermal and neural development through FGF signaling

Alternative splicing of pre-mRNAs is an important means of regulating developmental processes, yet the molecular mechanisms governing alternative splicing in embryonic contexts are just beginning to emerge. Polyglutamine-binding protein 1 (PQBP1) is an RNA-splicing factor that, when mutated, in humans causes Renpenning syndrome, an X-linked intellectual disability disease characterized by severe cognitive impairment, but also by physical defects that suggest PQBP1 has broader functions in embryonic development. Here, we reveal essential roles for PQBP1 and a binding partner, WBP11, in early development of Xenopus embryos. Both genes are expressed in the nascent mesoderm and neurectoderm, and morpholino knockdown of either causes defects in differentiation and morphogenesis of the mesoderm and neural plate. At the molecular level, knockdown of PQBP1 in Xenopus animal cap explants inhibits target gene induction by FGF but not by BMP, Nodal or Wnt ligands, and knockdown of either PQBP1 or WBP11 in embryos inhibits expression of fgf4 and FGF4-responsive cdx4 genes. Furthermore, PQBP1 knockdown changes the alternative splicing of FGF receptor-2 (FGFR2) transcripts, altering the incorporation of cassette exons that generate receptor variants (FGFR2 IIIb or IIIc) with different ligand specificities. Our findings may inform studies into the mechanisms underlying Renpenning syndrome.

Occupancy of tissue-specific cis-regulatory modules by Otx2 and TLE/Groucho for embryonic head specification

Head specification by the head-selector gene, orthodenticle (otx), is highly conserved among bilaterian lineages. However, the molecular mechanisms by which Otx and other transcription factors (TFs) interact with the genome to direct head formation are largely unknown. Here we employ ChIP-seq and RNA-seq approaches in Xenopus tropicalis gastrulae and find that occupancy of the corepressor, TLE/Groucho, is a better indicator of tissue-specific cis-regulatory modules (CRMs) than the coactivator p300, during early embryonic stages. On the basis of TLE binding and comprehensive CRM profiling, we define two distinct types of Otx2- and TLE-occupied CRMs. Using these devices, Otx2 and other head organizer TFs (for example, Lim1/Lhx1 (activator) or Goosecoid (repressor)) are able to upregulate or downregulate a large battery of target genes in the head organizer. An underlying principle is that Otx marks target genes for head specification to be regulated positively or negatively by partner TFs through specific types of CRMs.

The novel secreted factor MIG-18 acts with MIG-17/ADAMTS to control cell migration in Caenorhabditis elegans

The migration of Caenorhabditis elegans gonadal distal tip cells (DTCs) offers an excellent model to study the migration of epithelial tubes in organogenesis. mig-18 mutants cause meandering or wandering migration of DTCs during gonad formation, which is very similar to that observed in animals with mutations in mig-17, which encodes a secreted metalloprotease of the ADAMTS (a disintegrin and metalloprotease with thrombospondin motifs) family. MIG-18 is a novel secreted protein that is conserved only among nematode species. The mig-17(null) and mig-18 double mutants exhibited phenotypes similar to those in mig-17(null) single mutants. In addition, the mutations in fbl-1/fibulin-1 and let-2/collagen IV that suppress mig-17 mutations also suppressed the mig-18 mutation, suggesting that mig-18 and mig-17 function in a common genetic pathway. The Venus-MIG-18 fusion protein was secreted from muscle cells and localized to the gonadal basement membrane, a tissue distribution reminiscent of that observed for MIG-17. Overexpression of MIG-18 in mig-17 mutants and vice versa partially rescued the relevant DTC migration defects, suggesting that MIG-18 and MIG-17 act cooperatively rather than sequentially. We propose that MIG-18 may be a cofactor of MIG-17/ADAMTS that functions in the regulation of the gonadal basement membrane to achieve proper direction of DTC migration during gonadogenesis.

Extracellular metalloproteinases in neural crest development and craniofacial morphogenesis

The neural crest (NC) is a population of migratory stem/progenitor cells that is found in early vertebrate embryos. NC cells are induced during gastrulation, and later migrate to multiple destinations and contribute to many types of cells and tissues, such as craniofacial structures, cardiac tissues, pigment cells and the peripheral nervous system. Recently, accumulating evidence suggests that many extracellular metalloproteinases, including matrix metalloproteinases (MMPs), a disintegrin and metalloproteinases (ADAMs), and ADAMs with thrombospondin motifs (ADAMTSs), play important roles in various stages of NC development. Interference with metalloproteinase functions often causes defects in craniofacial structures, as well as in other cells and tissues that are contributed by NC cells, in humans and other vertebrates. In this review, we summarize the current state of the field concerning the roles of these three families of metalloproteinases in NC development and related tissue morphogenesis, with a special emphasis on craniofacial morphogenesis.

Microarray analysis of mRNA from cumulus cells following in vivo or in vitro maturation of mouse cumulus–oocyte complexes

The IVM of mammalian cumulus–oocyte complexes (COCs) yields reduced oocyte developmental competence compared with oocytes matured in vivo. Altered cumulus cell function during IVM is implicated as one cause for this difference. We have conducted a microarray analysis of cumulus cell mRNA following IVM or in vivo maturation (IVV). Mouse COCs were sourced from ovaries of 21-day-old CBAB6F1 mice 46 h after equine chorionic gonadotrophin (5 IU, i.p.) or from oviducts following treatment with 5 IU eCG (61 h) and 5 IU human chorionic gonadotrophin (13 h). IVM was performed in α-Minimal Essential Medium with 50 mIU FSH for 17 h. Three independent RNA samples were assessed using the Affymetrix Gene Chip Mouse Genome 430 2.0 array (Affymetrix, Santa Clara, CA, USA). In total, 1593 genes were differentially expressed, with 811 genes upregulated and 782 genes downregulated in IVM compared with IVV cumulus cells; selected genes were validated by real-time reverse transcription–polymerase chain reaction (RT-PCR). Surprisingly, haemoglobin α (Hba-a1) was highly expressed in IVV relative to IVM cumulus cells, which was verified by both RT-PCR and western blot analysis. Because haemoglobin regulates O2 and/or nitric oxide availability, we postulate that it may contribute to regulation of these gases during the ovulatory period in vivo. These data will provide a useful resource to determine differences in cumulus cell function that are possibly linked to oocyte competence.

O-fucosylation of thrombospondin type 1 repeats restricts epithelial to mesenchymal transition (EMT) and maintains epiblast pluripotency during mouse gastrulation

Thrombospondin type 1 repeat (TSR) superfamily members regulate diverse biological activities ranging from cell motility to inhibition of angiogenesis. In this study, we verified that mouse protein O-fucosyltransferase-2 (POFUT2) specifically adds O-fucose to TSRs. Using two Pofut2 gene-trap lines, we demonstrated that O-fucosylation of TSRs was essential for restricting epithelial to mesenchymal transition in the primitive streak, correct patterning of mesoderm, and localization of the definitive endoderm. Although Pofut2 mutant embryos established anterior/posterior polarity, they underwent extensive mesoderm differentiation at the expense of maintaining epiblast pluripotency. Moreover, mesoderm differentiation was biased towards the vascular endothelial cell lineage. Localization of Foxa2 and Cer1 expressing cells within the interior of Pofut2 mutant embryos suggested that POFUT2 activity was also required for the displacement of the primitive endoderm by definitive endoderm. Notably, Nodal, BMP4, Fgf8, and Wnt3 expression were markedly elevated and expanded in Pofut2 mutants, providing evidence that O-fucose modification of TSRs was essential for modulation of growth factor signaling during gastrulation. The ability of Pofut2 mutant embryos to form teratomas comprised of tissues from all three germ layer origins suggested that defects in Pofut2 mutant embryos resulted from abnormalities in the extracellular environment. This prediction is consistent with the observation that POFUT2 targets are constitutive components of the extracellular matrix (ECM) or associate with the ECM. For this reason, the Pofut2 mutants represent a valuable tool for studying the role of O-fucosylation in ECM synthesis and remodeling, and will be a valuable model to study how post-translational modification of ECM components regulates the formation of tissue boundaries, cell movements, and signaling.

The RNA-binding protein Mex3b has a fine-tuning system for mRNA regulation in early Xenopus development

Post-transcriptional control by RNA-binding proteins is a precise way to assure appropriate levels of gene expression. Here, we identify a novel mRNA regulatory system involving Mex3b (RKHD3) and demonstrate its role in FGF signaling. mex3b mRNA has a 3' long conserved UTR, named 3'LCU, which contains multiple elements for both mRNA destabilization and translational enhancement. Notably, Mex3b promotes destabilization of its own mRNA by binding to the 3'LCU, thereby forming a negative autoregulatory loop. The combination of positive regulation and negative autoregulation constitutes a fine-tuning system for post-transcriptional control. In early embryogenesis, Mex3b is involved in anteroposterior patterning of the neural plate. Consistent with this, Mex3b can attenuate FGF signaling and destabilize mRNAs for the FGF signaling components Syndecan 2 and Ets1b through their 3' UTRs. These data suggest that the 3'LCU-mediated fine-tuning system determines the appropriate level of mex3b expression, which in turn contributes to neural patterning through regulating FGF signaling.

A disintegrin-like and metalloprotease (reprolysin-type) with thrombospondin type 1 motif (ADAMTS) superfamily: functions and mechanisms

Together with seven ADAMTS-like proteins, the 19 mammalian ADAMTS proteases constitute a superfamily. ADAMTS proteases are secreted zinc metalloproteases whose hallmark is an ancillary domain containing one or more thrombospondin type 1 repeats. ADAMTS-like proteins resemble ADAMTS ancillary domains and lack proteolytic activity. Vertebrate expansion of the superfamily reflects emergence of new substrates, duplication of proteolytic activities in new contexts, and cooperative functions of the duplicated genes. ADAMTS proteases are involved in maturation of procollagen and von Willebrand factor, as well as in extracellular matrix proteolysis relating to morphogenesis, angiogenesis, ovulation, cancer, and arthritis. New insights into ADAMTS mechanisms indicate significant regulatory roles for ADAMTS ancillary domains, propeptide processing, and glycosylation. ADAMTS-like proteins appear to have regulatory roles in the extracellular matrix.

Genetic inactivation of ADAMTS15 metalloprotease in human colorectal cancer

Matrix metalloproteinases have been traditionally linked to cancer dissemination through their ability to degrade most extracellular matrix components, thus facilitating invasion and metastasis of tumor cells. However, recent functional studies have revealed that some metalloproteases, including several members of the ADAMTS family, also exhibit tumor suppressor properties. In particular, ADAMTS1, ADAMTS9, and ADAMTS18 have been found to be epigenetically silenced in malignant tumors of different sources, suggesting that they may function as tumor suppressor genes. Herein, we show that ADAMTS15 is genetically inactivated in colon cancer. We have performed a mutational analysis of the ADAMTS15 gene in human colorectal carcinomas, with the finding of four mutations in 50 primary tumors and 6 colorectal cancer cell lines. Moreover, functional in vitro and in vivo studies using HCT-116 and SW-620 colorectal cancer cells and severe combined immunodeficient mice have revealed that ADAMTS15 restrains tumor growth and invasion. Furthermore, the presence of ADAMTS15 in human colorectal cancer samples showed a negative correlation with the histopathologic differentiation grade of the corresponding tumors. Collectively, these results provide evidence that extracellular proteases, including ADAMTS15, may be targets of inactivating mutations in human cancer and further validate the concept that secreted metalloproteases may show tumor suppressor properties.

A chemical genomic approach identifies matrix metalloproteinases as playing an essential and specific role in Xenopus melanophore migration

To dissect the function of matrix metalloproteinases (MMPs) involved in cellular migration in vivo, we undertook both a forward chemical genomic screen and a functional approach to discover modulators of melanophore (pigment cell) migration in Xenopus laevis. We identified the 8-quinolinol derivative NSC 84093 as affecting melanophore migration in the developing embryo and have shown it to act as a MMP inhibitor. Potential targets of NSC 84093 investigated include MMP-14 and MMP-2. MMP-14 is expressed in migrating neural crest cells from which melanophores are derived. MMP-2 is expressed at the relevant time of development and in a pattern that suggests it contributes to melanophore migration. Morpholino-mediated knockdown of both MMPs demonstrates they play a key role in melanophore migration and partially phenocopy the effect of NSC 84093.

Involvement of an inner nuclear membrane protein, Nemp1, in Xenopus neural development through an interaction with the chromatin protein BAF

To clarify the molecular mechanisms of neural development in vertebrates, we analyzed a novel gene, termed nemp1 (nuclear envelope integral membrane protein 1), which is expressed in the Xenopus anterior neuroectoderm at the neurula stage. Nemp1 has a putative signal peptide and five transmembrane domains, but does not have any other known domains. We show that Nemp1 is localized to the inner nuclear membrane (INM) with its evolutionarily conserved C-terminal region facing the nucleoplasm. Both overexpression and knockdown of Nemp1 in Xenopus embryos reduced the expression of early eye marker genes, rax, tbx3, and pax6, and later resulted mainly in severe eye defects at the tailbud stage. In contrast, the expression of a forebrain/midbrain marker, otx2, and a pan-neural marker, sox2, was largely unaffected. Deletion analysis of Nemp1 showed that nuclear envelope-localization of the C-terminal region is necessary for its eye-reducing activity. Furthermore, nemp1 is coexpressed with baf (barrier-to-autointegration factor) in the eye anlagen, and that Nemp1 interacts with BAF through the BAF-binding site in the C-terminal region and this site is required for Nemp1 activity. These data suggest that Nemp1 is involved in the expression of eye marker genes by functioning at the INM at least partly through BAF.

Lrig3 regulates neural crest formation in Xenopus by modulating Fgf and Wnt signaling pathways

Leucine-rich repeats and immunoglobulin-like domains 3 (Lrig3) was identified by microarray analysis among genes that show differential expression during gastrulation in Xenopus laevis. Lrig3 was expressed in the neural plate and neural crest (NC) at neurula stages, and in NC derivatives and other dorsal structures during tailbud stages. A prominent consequence of the morpholino-induced inhibition of Lrig3 expression was impaired NC formation, as revealed by the suppression of marker genes, including Slug, Sox9 and Foxd3. In the NC induction assay involving Chordin plus Wnt3a-injected animal caps, Lrig3 morpholino inhibited expression of Slug, Sox9 and Foxd3, but not of Pax3 and Zic1. In line with this, Lrig3 knockdown prevented NC marker induction by Pax3 and Zic1, suggesting that Lrig3 acts downstream of these two genes in NC formation. Injection of Lrig3 and Wnt3a led to low-level induction of NC markers and enhanced induction of Fgf3, Fgf4 and Fgf8 in animal caps, suggesting a positive role for Lrig3 in Wnt signaling. Lrig3 could attenuate Fgf signaling in animal caps, did interact with Fgf receptor 1 in cultured cells and, according to context, decreased or increased the induction of NC markers by Fgf. We suggest that Lrig3 functions in NC formation in Xenopus by modulating the Wnt and Fgf signaling pathways.

The ADAMTS12 metalloproteinase exhibits anti-tumorigenic properties through modulation of the Ras-dependent ERK signalling pathway

Members of the ADAMTS (a disintegrin and metalloproteinase with thrombospondin motifs) family of proteolytic enzymes are implicated in a variety of physiological processes, such as collagen maturation, organogenesis, angiogenesis, reproduction and inflammation. Moreover, deficiency or overexpression of certain ADAMTS proteins is directly involved in serious human diseases, including cancer. However, the functional roles of other family members, such as ADAMTS12, remain unknown. Here, by using different in vitro and in vivo approaches, we have evaluated the possible role of ADAMTS12 in the development and progression of cancer. First, we show that expression of ADAMTS12 in Madin-Darby canine kidney (MDCK) cells prevents the tumorigenic effects of hepatocyte growth factor (HGF) by blocking the activation of the Ras-MAPK signalling pathway and that this regulation involves the thrombospondin domains of the metalloproteinase. We also show that addition of recombinant human ADAMTS12 to bovine aortic endothelial cells (BAE-1 cells) abolishes their ability to form tubules upon stimulation with vascular endothelial growth factor (VEGF). Additionally, tumours induced in immunodeficient SCID mice injected with A549 cells overexpressing ADAMTS12 show a remarkable growth deficiency in comparison with tumours formed in animals injected with parental A549 cells. Overall, our data suggest that ADAMTS12 confers tumour-protective functions upon cells that produce this proteolytic enzyme.