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F van Roy

Publications and source records attributed to F van Roy.

At least 19 recordsLinked to original sources
PubMed2006

Regulation of vimentin by SIP1 in human epithelial breast tumor cells.

The expression of Smad interacting protein-1 (SIP1; ZEB2) and the de novo expression of vimentin are frequently involved in epithelial-to-mesenchymal transitions (EMTs) under both normal and pathological conditions. In the present study, we investigated the potential role of SIP1 in the regulation of vimentin during the EMT associated with breast tumor cell migration and invasion. Examining several breast tumor cell lines displaying various degrees of invasiveness, we found SIP1 and vimentin expression only in invasive cell lines. Also, using a model of cell migration with human mammary MCF10A cells, we showed that SIP1 is induced specifically in vimentin-positive migratory cells. Furthermore, transfection of SIP1 cDNA in MCF10A cells increased their vimentin expression both at the mRNA and protein levels and enhanced their migratory abilities in Boyden Chamber assays. Inversely, inhibition of SIP1 expression by RNAi strategies in BT-549 cells and MCF10A cells decreased vimentin expression. We also showed that SIP1 transfection did not activate the TOP-FLASH reporter system, suggesting that the beta-catenin/TCF pathway is not implicated in the regulation of vimentin by SIP1. Our results therefore implicate SIP1 in the regulation of vimentin observed in the EMT associated with breast tumor cell migration, a pathway that may contribute to the metastatic progression of breast cancer.

Base Sequence↗
PubMed2005

delta-Protocadherins: a gene family expressed differentially in the mouse brain.

Phylogenetic analysis of protocadherin genes identified a new gene subfamily, the delta-protocadherins, containing several conserved motifs in their cytoplasmic domains. This subfamily can be further subdivided into two subgroups, named delta1-protocadherins (comprising protocadherin-1, -7, -9, and -11 or X/Y) and delta2-protocadherins (comprising protocadherin-8, -10, -17, -18, and -19). The members of the delta1-protocadherin subgroup were analyzed in greater detail here. They share a similar gene structure that results in the expression of multiple alternative transcripts. All members of this subgroup have at least one transcript that contains a binding site for protein phosphatase-1alpha. Like most classic cadherins, each of three delta1-protocadherins analyzed in this study by in situ hybridization showed a unique expression pattern that differed from the patterns of the other delta1-protocadherins. Together, these results suggest that the members of the delta1-protocadherin subgroup exercise tightly regulated functions in the development, regionalization, and functional differentiation of the mouse brain.

Amino Acid Sequence↗
PubMed2005

delta-Protocadherins: unique structures and functions.

delta-Protocadherins constitute a group of cadherins characterized by several conserved motifs in their cytoplasmic domains. We present a phylogenetic analysis that further divides this group into delta1-protocadherins (comprising protocadherin-1, -7, -9 and -11 or -X/Y) and delta2-protocadherins (comprising protocadherin-8, -10, -17, -18 and -19). The delta-protocadherin genes, which are located on different chromosomes in man and mouse, have a similar gene structure. They are expressed as multiple splice forms, differing mostly in their cytoplasmic domains. Some delta-protocadherins were reported to mediate weak cell-cell adhesion in vitro and cell sorting in vivo. In addition, individual delta-protocadherins might play important roles in signaling pathways, as they bind to proteins such as TAF1/Set, protein phosphatase-1alpha and the Frizzled 7 receptor. The spatiotemporally restricted expression of delta-protocadherins in different tissues and species and the results of their functional analysis, mainly in Xenopus, suggest that they play multiple, tightly regulated roles in vertebrate development.

Alternative Splicing↗
PubMed2003

Inflammatory breast cancer shows angiogenesis with high endothelial proliferation rate and strong E-cadherin expression.

Inflammatory breast cancer (IBC) is the most aggressive form of breast cancer. Improved understanding of the mechanisms responsible for the differences between IBC and non-IBC might provide novel therapeutic targets. We studied 35 consecutive patients with IBC, biopsied prior to the initiation of chemotherapy. Angiogenesis was evaluated by Chalkley counting and by assessment of endothelial cell proliferation (ECP) and vessel maturity. The presence of fibrin, expression of the hypoxia marker carbonic anhydrase IX (CA IX) and epithelialcadherin (E-cadherin) expression were immunohistochemically detected. The same parameters were obtained in a group of 104 non-IBC patients. Vascular density, assessed by Chalkley counting (P<0.0001), and ECP (P=0.01) were significantly higher in IBC than in non-IBC. Abundant stromal fibrin deposition was observed in 26% of IBC and in only 8% of non-IBC (P=0.02). Expression of CA IX was significantly less frequent in IBC than in non-IBC with early metastasis (P=0.047). There was a significant positive correlation between the expression of CA IX and ECP in IBC (r=0.4, P=0.03), implying that the angiogenesis is partly hypoxia driven. However, the higher ECP in IBC and the less frequent expression of CA IX in IBC vs non-IBC points at a role for other factors than hypoxia in stimulating angiogenesis. Strong, homogeneous E-cadherin expression was found at cell-cell contacts in all but two IBC cases, both in lymphovascular tumour emboli and in infiltrating tumour cells, challenging our current understanding of the metastatic process. Both the intense angiogenesis and the strong E-cadherin expression may contribute to the highly metastatic phenotype of IBC.

Adult↗
PubMed2001

The lipid phosphatase activity of PTEN is critical for stabilizing intercellular junctions and reverting invasiveness.

To analyze the implication of PTEN in the control of tumor cell invasiveness, the canine kidney epithelial cell lines MDCKras-f and MDCKts-src, expressing activated Ras and a temperature-sensitive v-Src tyrosine kinase, respectively, were transfected with PTEN expression vectors. Likewise, the human PTEN-defective glioblastoma cell lines U87MG and U373MG, the melanoma cell line FM-45, and the prostate carcinoma cell line PC-3 were transfected. We demonstrate that ectopic expression of wild-type PTEN in MDCKts-src cells, but not expression of PTEN mutants deficient in either the lipid or both the lipid and protein phosphatase activities, reverted the morphological transformation, induced cell-cell aggregation, and suppressed the invasive phenotype in an E-cadherin-dependent manner. In contrast, overexpression of wild-type PTEN did not counteract Ras-induced invasiveness of MDCKras-f cells expressing low levels of E-cadherin. PTEN effects were not associated with marked changes in accumulation or phosphorylation levels of E-cadherin and associated catenins. Wild-type, but not mutant, PTEN also reverted the invasive phenotype of U87MG, U373MG, PC-3, and FM-45 cells. Interestingly, PTEN effects were mimicked by N-cadherin-neutralizing antibody in the glioblastoma cell lines. Our data confirm the differential activities of E- and N-cadherin on invasiveness and suggest that the lipid phosphatase activity of PTEN exerts a critical role in stabilizing junctional complexes and restraining invasiveness.

Animals↗
PubMed2001

The human and murine protocadherin-beta one-exon gene families show high evolutionary conservation, despite the difference in gene number.

Extensive cDNA analysis demonstrated that all human and mouse protocadherin-beta genes are one-exon genes. The protein sequences of these genes are highly conserved, especially the three most membrane-proximal extracellular domains. Phylogenetic analysis suggested that this unique gene family evolved by duplication of one single protocadherin-beta gene to 15 copies. The final difference in the number of protocadherin-beta genes in man (#19) and mouse (#22) is probably caused by duplications later in evolution. The complex relationship between human and mouse genes and the lack of pseudogenes in the mouse protocadherin-beta gene cluster suggest a species-specific evolutionary pressure for maintenance of numerous protocadherin-beta genes.

Amino Acid Sequence↗
PubMed2001

The two-handed E box binding zinc finger protein SIP1 downregulates E-cadherin and induces invasion.

Transcriptional downregulation of E-cadherin appears to be an important event in the progression of various epithelial tumors. SIP1 (ZEB-2) is a Smad-interacting, multi-zinc finger protein that shows specific DNA binding activity. Here, we report that expression of wild-type but not of mutated SIP1 downregulates mammalian E-cadherin transcription via binding to both conserved E2 boxes of the minimal E-cadherin promoter. SIP1 and Snail bind to partly overlapping promoter sequences and showed similar silencing effects. SIP1 can be induced by TGF-beta treatment and shows high expression in several E-cadherin-negative human carcinoma cell lines. Conditional expression of SIP1 in E-cadherin-positive MDCK cells abrogates E-cadherin-mediated intercellular adhesion and simultaneously induces invasion. SIP1 therefore appears to be a promoter of invasion in malignant epithelial tumors.

Animals↗
PubMed2001

alphaT-catenin: a novel tissue-specific beta-catenin-binding protein mediating strong cell-cell adhesion.

Cadherins are major cell-cell adhesion proteins whose cytoplasmic domains bind to catenin proteins. Strong intercellular adhesion depends on linkage of the cadherin/catenin complex to the actin cytoskeleton via alpha-catenin. To date, it is not clear how different cell types achieve the variable strength of cell-cell adhesion clearly needed in a multicellular organism. Here, we report the cloning and molecular characterization of alphaT(testis)-catenin, a novel human cDNA encoding a protein with homology to both human alphaE(epithelial)-catenin and alphaN(neural)-catenin. Although originally discovered in testis, alphaT-catenin is expressed in other tissues, the highest levels being observed in heart. Immunohistochemical analysis showed human alphaT-catenin localization at intercalated discs of cardiomyocytes and in peritubular myoid cells of testis. In cells transfected with alphaT-catenin cDNA, interaction with beta-catenin was demonstrated by co-immunoprecipitation. Transfection of alpha-catenin-deficient colon carcinoma cells recruited E-cadherin and beta-catenin to cell-cell contacts and functional cadherin-mediated cell-cell adhesion was restored in this way. Moreover, compaction of these cells was at least as prominent as in the case of cells expressing endogenous alphaE-catenin. We propose that alphaT-catenin is necessary for the formation of stretch-resistant cell-cell adhesion complexes, in particular, muscle cells.

Amino Acid Sequence↗
PubMed2000

Characterization of three novel human cadherin genes (CDH7, CDH19, and CDH20) clustered on chromosome 18q22-q23 and with high homology to chicken cadherin-7.

Full-length coding sequences of two novel human cadherin cDNAs were obtained by sequence analysis of several EST clones and 5' and 3' rapid amplification of cDNA ends (RACE) products. Exons for a third cDNA sequence were identified in a public-domain human genomic sequence, and the coding sequence was completed by 3' RACE. One of the sequences (CDH7L1, HGMW-approved gene symbol CDH7) is so similar to chicken cadherin-7 gene that we consider it to be the human orthologue. In contrast, the published partial sequence of human cadherin-7 is identical to our second cadherin sequence (CDH7L2), for which we propose CDH19 as the new name. The third sequence (CDH7L3, HGMW-approved gene symbol CDH20) is almost identical to the mouse "cadherin-7" cDNA. According to phylogenetic analysis, this mouse cadherin-7 and its here presented human homologue are most likely the orthologues of Xenopus F-cadherin. These novel human genes, CDH7, CDH19, and CDH20, are localized on chromosome 18q22-q23, distal of both the gene CDH2 (18q11) encoding N-cadherin and the locus of the six desmosomal cadherin genes (18q12). Based on genetic linkage maps, this genomic region is close to the region to which Paget's disease was linked. Interestingly, the expression patterns of these three closely related cadherins are strikingly different.

Amino Acid Sequence↗
PubMed2000

The protein-tyrosine phosphatase SHP-1 binds to and dephosphorylates p120 catenin.

A prominent tyrosine-phosphorylated protein of approximately 100 kDa (designated pp100) in epidermal growth factor (EGF)-stimulated A431 cells was found to be a main interaction partner of the protein-tyrosine phosphatase SHP-1 in pull-down experiments with a glutathione S-transferase-SHP-1 fusion protein. Binding was largely mediated by the N-terminal SH2 domain of SHP-1 and apparently direct and independent from the previously described association of SHP-1 with the activated EGF receptor. pp100 was partially purified and identified by mass spectrometric analysis of tryptic fragments, partial amino acid sequencing, and use of authentic antibodies as the 3A isoform of the Armadillo repeat protein superfamily member p120 catenin (p120(ctn)). Different p120(ctn) isoforms expressed in human embryonal kidney 293 cells, exhibited differential binding to SHP-1 that correlated partly with the extent of EGF-dependent p120(ctn) tyrosine phosphorylation. Despite strong phosphorylation, p120(ctn) isoforms 3B and 3AB bound, however, less readily to SHP-1. SHP-1 associated transiently with p120(ctn) in EGF-stimulated A431 cells stably transfected with a tetracycline-responsive SHP-1 expression construct, and p120(ctn) exhibited elevated phosphorylation upon a tetracycline-mediated decrease in the SHP-1 level. Functions of p120(ctn), which are regulated by tyrosine phosphorylation, may be modulated by the described SHP-1-p120(ctn) interaction.

Catenins↗
PubMed2000

Phylogenetic analysis of the cadherin superfamily allows identification of six major subfamilies besides several solitary members.

Cadherins play an important role in specific cell-cell adhesion events. Their expression appears to be tightly regulated during development and each tissue or cell type shows a characteristic pattern of cadherin molecules. Inappropriate regulation of their expression levels or functionality has been observed in human malignancies, in many cases leading to aggravated cancer cell invasion and metastasis. The cadherins form a superfamily with at least six subfamilies, which can be distinguished on the basis of protein domain composition, genomic structure, and phylogenetic analysis of the protein sequences. These subfamilies comprise classical or type-I cadherins, atypical or type-II cadherins, desmocollins, desmogleins, protocadherins and Flamingo cadherins. In addition, several cadherins clearly occupy isolated positions in the cadherin superfamily (cadherin-13, -15, -16, -17, Dachsous, RET, FAT, MEGF1 and most invertebrate cadherins). We suggest a different evolutionary origin of the protocadherin and Flamingo cadherin genes versus the genes encoding desmogleins, desmocollins, classical cadherins, and atypical cadherins. The present phylogenetic analysis may accelerate the functional investigation of the whole cadherin superfamily by allowing focused research of prototype cadherins within each subfamily.

Amino Acid Sequence↗
PubMed2000

The p300/CBP acetyltransferases function as transcriptional coactivators of beta-catenin in vertebrates.

Wnt growth factors regulate a variety of developmental processes by altering specific gene expression patterns. In vertebrates beta-catenin acts as transcriptional activator, which is needed to overcome target gene repression by Groucho/TLE proteins, and to permit promoter activation as the final consequence of Wnt signaling. However, the molecular mechanisms of transcriptional activation by beta-catenin are only poorly understood. Here we demonstrate that the closely related acetyltransferases p300 and CBP potentiate beta-catenin-mediated activation of the siamois promoter, a known Wnt target. beta-catenin and p300 also synergize to stimulate a synthetic reporter gene construct, whereas activation of the cyclin D1 promoter by beta-catenin is refractory to p300 stimulation. Axis formation and activation of the beta-catenin target genes siamois and Xnr-3 in Xenopus embryos are sensitive to the E1A oncoprotein, a known inhibitor of p300/CBP. The C-terminus of beta-catenin interacts directly with a region overlapping the CH-3 domain of p300. p300 could participate in alleviating promoter repression imposed by chromatin structure and in recruiting the basal transcription machinery to promoters of particular Wnt target genes.

Animals↗
PubMed1999

Predominance of beta-catenin mutations and beta-catenin dysregulation in sporadic aggressive fibromatosis (desmoid tumor).

Aggressive fibromatosis (also called desmoid tumor) occurs as a sporadic lesion or as part of Familial Adenomatous Polyposis, which is caused by germ line mutations in the Adenomatous polyposis Coli (APC) gene. APC is involved in the regulation of the cellular level of beta-catenin, which is a mediator in Wnt signaling. Mutational analysis of the beta-catenin and APC genes was performed in 42 sporadic aggressive fibromatoses. Nine tumors had mutations in APC, and 22 had a point mutation in beta-catenin at either codon 45 or codon 41 (producing a stabilized beta-catenin protein product). Immunohistochemistry showed an elevated beta-catenin protein level in all tumors, regardless of mutational status. Beta-catenin localized to the nucleus, and was not tyrosine phosphorylated in the six tumors in which this was tested. The demonstration of mutations in two mediators in the Wnt-APC-beta-catenin pathway implicates beta-catenin stabilization as the key factor in the pathogenesis of aggressive fibromatosis. This is the first demonstration of somatic beta-catenin mutations in a locally invasive, but non metastatic lesion composed of spindle cells, illustrating the importance of beta-catenin stabilization in a variety of cell types and neoplastic processes. Moreover, this tumor has one of the highest reported frequencies of beta-catenin mutations of any tumor type.

Base Sequence↗
PubMed1999

Human alpha-catulin, a novel alpha-catenin-like molecule with conserved genomic structure, but deviating alternative splicing.

A new human cDNA was cloned and termed alpha-catulin, based on sequence similarity with both alpha-CATenins and vincULIN. The mRNA is present ubiquitously, although low expression levels are found in neural tissues. The genomic organization of the alpha-catulin gene CTNNAL1 is closely related to that of the alphaE-catenin gene CTNNA1, but not at all to that of the vinculin gene. Alternative splicing of the last exon generates a frameshift, resulting in a truncated protein with a new carboxy-terminus.

Alternative Splicing↗
PubMed1999

Nuclear localization of the p120(ctn) Armadillo-like catenin is counteracted by a nuclear export signal and by E-cadherin expression.

The Armadillo protein p120(ctn) associates with the cytoplasmic domain of cadherins and accumulates at cell-cell junctions. Particular Armadillo proteins such as beta-catenin and plakophilins show a partly nuclear location, suggesting gene-regulatory activities. For different human E-cadherin-negative carcinoma cancer cell lines we found expression of endogenous p120(ctn) in the nucleus. Expression of E-cadherin directed p120(ctn) out of the nucleus. Previously, we reported that the human p120(ctn) gene might encode up to 32 protein isoforms as products of alternative splicing. Overexpression of p120(ctn) isoforms B in various cell lines resulted in cytoplasmic immunopositivity but never in nuclear staining. In contrast, upon expression of p120(ctn) cDNAs lacking exon B, the isoforms were detectable within both nuclei and cytoplasm. A putative nuclear export signal (NES) with a characteristic leucine-rich motif is encoded by exon B. This sequence element was shown to be required for nuclear export and to function autonomously when fused to a carrier protein and microinjected into cell nuclei. Moreover, the NES function of endogenously or exogenously expressed p120(ctn) isoforms B was sensitive to the nuclear export inhibitor leptomycin B. Expression of exogenous E-cadherin down-regulated nuclear p120(ctn) whereas activation of protein kinase C increased the level of nuclear p120(ctn). These results reveal molecular mechanisms controlling the subcellular distribution of p120(ctn).

Adenocarcinoma↗
PubMed1999

The human cadherin-10 gene: complete coding sequence, predominant expression in the brain, and mapping on chromosome 5p13-14.

In a quest for novel cadherin gene family members in the human dbEST database, an interesting EST clone was identified and chosen for subsequent analysis. Using the technique of 5' rapid amplification of cDNA ends, we isolated the complete coding sequence and a large part of the UTRs of a novel gene. The sequence appeared to correspond to the human cadherin-10 gene, whose sequence was only partially known before. The expression pattern of this cadherin was found to be largely brain-specific, with additional expression in both adult and fetal kidney, and with minor expression in prostate and fetal lung. By FISH analysis the genomic location was determined at human chromosome 5p13-14, which is nearby the reported positions of the human cadherin-6, -12, and cadherin-14 (CDH18) genes. Cadherin-10 shows high relationship to the human cadherin-6 gene.

Adult↗
PubMed1999

Beta-catenin mutations are more frequent in small colorectal adenomas than in larger adenomas and invasive carcinomas.

Loss of serine or threonine phosphorylation sites from exon 3 of beta-catenin has been identified in approximately half of colorectal tumors which lack adenomatous polyposis coli (APC) mutations, but the overall contribution of beta-catenin mutations to sporadic colorectal tumorigenesis is unclear. We therefore used PCR to amplify and sequence exon 3 of beta-catenin from 202 sporadic colorectal tumors. Exon 3 beta-catenin mutations were identified in 6 of 48 small (< 1 cm) adenomas, 2 of 82 large (> or =1 cm) adenomas, and 1 of 72 invasive carcinomas. Eight of the nine mutations, including all of those in the small adenomas and the invasive cancer, involved loss of serine or threonine phosphorylation sites. The percentage of beta-catenin mutations in small adenomas (12.5%) was significantly greater than that in large adenomas (2.4%) and invasive cancers (1.4%; P = 0.05 and P = 0.02, respectively). We conclude that mutation of beta-catenin can be an early, perhaps initiating, event in colorectal tumorigenesis. Small adenomas with beta-catenin mutations do not appear to be as likely to progress to larger adenomas and invasive carcinomas as other adenomas, however, with the result that beta-catenin mutations are only rarely seen in invasive cancers. This suggests that APC and beta-catenin mutations are not functionally equivalent, and that the APC gene may have other tumor suppressor functions besides the degradation of beta-catenin.

Adenoma↗