Abberant activation of the process of epithelial-mesenchymal transition in cancer cells is a late... more Abberant activation of the process of epithelial-mesenchymal transition in cancer cells is a late event in tumor progression. A key inducer of this transition is the transcription factor Snail, which represses E-cadherin. We report that conditional expression of the human transcriptional repressor Snail in colorectal cancer cells induces an epithelial dedifferentiation program that coincides with a drastic change in cell morphology. Snail target genes control the establishment of several junctional complexes, intermediate filament networks, and the actin cytoskeleton. Modulation of the expression of these genes is associated with loss of cell aggregation and induction of invasion. Chromatin immunoprecipitation experiments showed that repression of selected target genes is associated with increased binding of Snail to their promoters, which contain consensus Snail-binding sites. Thus, Snail constitutes a master switch that directly represses the epithelial phenotype, resulting in malignant carcinoma cells.
Supplementary Figure 2 from E-Cadherin Regulates Human Nanos1, which Interacts with p120ctn and I... more Supplementary Figure 2 from E-Cadherin Regulates Human Nanos1, which Interacts with p120ctn and Induces Tumor Cell Migration and Invasion
Supplementary Methods, Materials and Figure Legends 1-2 from E-Cadherin Regulates Human Nanos1, w... more Supplementary Methods, Materials and Figure Legends 1-2 from E-Cadherin Regulates Human Nanos1, which Interacts with p120ctn and Induces Tumor Cell Migration and Invasion
Supplementary Table 2 from The Transcription Factor Snail Induces Tumor Cell Invasion through Mod... more Supplementary Table 2 from The Transcription Factor Snail Induces Tumor Cell Invasion through Modulation of the Epithelial Cell Differentiation Program
Supplementary Table 1 from The Transcription Factor Snail Induces Tumor Cell Invasion through Mod... more Supplementary Table 1 from The Transcription Factor Snail Induces Tumor Cell Invasion through Modulation of the Epithelial Cell Differentiation Program
The human 1p36 region is deleted in many different types of tumors, and so it probably harbors on... more The human 1p36 region is deleted in many different types of tumors, and so it probably harbors one or more tumor suppressor genes. In a Belgian neuroblastoma patient, a constitutional balanced translocation t(1;17)(p36.2;q11.2) may have led to the development of the tumor by disrupting or activating a gene. Here, we report the cloning of both translocation breakpoints and the identification of a novel gene that is disrupted by this translocation. This gene, named NBPF1 for Neuroblastoma BreakPoint Family member 1, belongs to a recently described gene family encoding highly similar proteins, the functions of which are unknown. The translocation truncates NBPF1 and gives rise to two chimeric transcripts of NBPF1 sequences fused to sequences derived from chromosome 17. On chromosome 17, the translocation disrupts one of the isoforms of ACCN1, a potential glioma tumor suppressor gene. Expression of the NBPF family in neuroblastoma cell lines is highly variable, but it is decreased in cell lines that have a deletion of chromosome 1p. More importantly, expression profiling of the NBPF1 gene showed that its expression is significantly lower in cell lines with heterozygous NBPF1 loss than in cell lines with a normal 1p chromosome. Meta-analysis of the expression of NBPF and ACCN1 in neuroblastoma tumors indicates a role for the NBPF genes and for ACCN1 in tumor aggressiveness. Additionally, DLD1 cells with inducible NBPF1 expression showed a marked decrease of clonal growth in a soft agar assay. The disruption of both NBPF1 and ACCN1 genes in this neuroblastoma patient indicates that these genes might suppress development of neuroblastoma and possibly other tumor types.
Proceedings of the National Academy of Sciences of the United States of America, Dec 1, 1989
Tumor necrosis factor (TNF) is cytotoxic for several transformed cell lines in vitro. In the pres... more Tumor necrosis factor (TNF) is cytotoxic for several transformed cell lines in vitro. In the presence of LiCI, the murine fibrosarcoma cell lines L929 and WEHI 164 done 13 became >10 times more sensitive to TNF-mediated cyto-
E-cadherin-mediated cell-cell adhesion is critical for naive pluripotency of cultured mouse embry... more E-cadherin-mediated cell-cell adhesion is critical for naive pluripotency of cultured mouse embryonic stem cells (mESCs). E-cadherin-depleted mESC fail to downregulate their pluripotency program and are unable to initiate lineage commitment. To further explore the roles of cell adhesion molecules during mESC differentiation, we focused on p120 catenin (p120ctn). Although one key function of p120ctn is to stabilize and regulate cadherin-mediated cell-cell adhesion, it has many additional functions, including regulation of transcription and Rho GTPase activity. Here, we investigated the role of mouse p120ctn in early embryogenesis, mESC pluripotency and early fate determination. In contrast to the E-cadherin-null phenotype, p120ctn-null mESCs remained pluripotent, but their in vitro differentiation was incomplete. In particular, they failed to form cystic embryoid bodies and showed defects in primitive endoderm formation. To pinpoint the underlying mechanism, we undertook a structure-...
Hyperactivation of the Wnt pathway is a common hallmark of many cancers. Deregulation of the path... more Hyperactivation of the Wnt pathway is a common hallmark of many cancers. Deregulation of the pathway is mostly due to mutations in the tumor suppressor gene Adenomatous Polyposis Coli (APC) or the transcriptional regulator of the Wnt pathway β-catenin (CTNNB1). Heterozygous germline mutations in the Mutation Cluster Region (MCR) of the APC gene cause Familial Adenomatous Polyposis (FAP), a condition characterized by multiple colorectal polyps, which over time become malignant. FAP patients also frequently suffer from extracolonic manifestations, such as Congenital Hypertrophy of the Retinal Pigment Epithelium (CHRPE), desmoid tumors and medulloblastoma. Despite many mouse models and the clear etiology of colorectal cancer and FAP, no drugs targeting the Wnt pathway have reached the clinic and there is a need for new genetic animal models. The recent TALEN (Transcription Activator Like Effector Nuclease) and CRISPR/Cas9 gene targeting technologies open the door for novel genetic canc...
Tumor necrosis factor (TNF), first described as a cytokine with tumor- necrotizing activity, is n... more Tumor necrosis factor (TNF), first described as a cytokine with tumor- necrotizing activity, is now known to be a pleiotropic molecule. The mo lecular mechanisms responsible for the cytotoxic activity of TNF on ma lignant cells are still largely unknown. In this study, we report that the protein kinase inhibitor Staurosporine (56 to 1500 UM i increases about 500 times
Abstract A specific deletion mutant of human adenovirus type 2 (Ad2) was detected when pools of w... more Abstract A specific deletion mutant of human adenovirus type 2 (Ad2) was detected when pools of wild-type Ad2 were grown at high multiplicity of infection in HeLa cells. This deletion mutant, designated dl-Ad2, was enriched when the defective Ad2-SV40 hybrids of the Ad2 ++ HEY population were cloned in monkey cells in the presence of an added excess of wild-type Ad2. Electron microscope heteroduplex analysis and restriction endonuclease examination established the Ad-specific nature of the dl-Ad2 DNA and revealed a single, homogeneous deletion of about 0.08 to 0.09 fractional genome length situated between 0.78 and 0.87 Ad2 map unit. This genome structure is very similar to that of several other incomplete adenoviruses already described. The deleted segment encompasses one of the four early genome regions of Ad2. dl-Ad2 particles are not infectious in both human and monkey cells, although the mutant DNA is replicated in these cell types. dl-Ad2 is able to interfere efficiently with SV40 DNA replication in coinfected monkey cells. Furthermore, virus populations could be cloned consisting exclusively of Ad2 ++ HEY hybrid viruses and dl-Ad2 “helper” viruses, indicating that dl-Ad2 can complement sufficiently for the large Ad2 DNA deletion in the Ad2 ++ HEY hybrid genomes.
The International Journal of Developmental Biology, 2010
During and after gastrulation, the neural axis in vertebrates is patterned along the antero-poste... more During and after gastrulation, the neural axis in vertebrates is patterned along the antero-posterior axis by the combined activity of signaling factors secreted in the neural ectoderm and the underlying mesoderm. These signals divide the neural axis into four major divisions: the forebrain, midbrain, hindbrain and spinal chord. Among the signals that pattern the neural axis, Wnts play a prominent role and many patterning genes have been found to be direct Wnt/ catenin target genes, including several homeobox domain-containing transcription factors. Here we show that HoxD1 and Irx3 are transcriptionally induced by the Wnt pathway during neurulation. Using induction in the presence of the translation blocking drug cycloheximide and chromatin immunoprecipitation assays, we confirm that HoxD1 and Irx3 are both direct Wnt target genes. In addition, we identified Crabp2 (cellular retinoic acid binding protein 2) as an indirect target that potentially links the activities of Wnt and retinoic acid during antero-posterior patterning.
Fischer rat cells before and after transfection with immortalizing and transforming genes produce... more Fischer rat cells before and after transfection with immortalizing and transforming genes produced tumours after s.c., i.p., or i.v. injection of cell suspensions and after s.c. implantation of cellular aggregates in the tail of syngeneic rats. Tumours were described histologically as fibrosarcoma-like. Virtually all tumours were considered macroscopically to be invasive because they adhered to the neighbouring tissues; in many tumours invasion was confirmed microscopically. All types of cells produced lung colonies (artificial metastases) after i.v. injection. Spontaneous metastases (from a primary tumour) were found with some tumours produced by cells before as well as after transfection. Differences in metastasis between various cell types could not be ascribed to variations in the periods of observation, in the minimum tumour-bearing periods, in the latency periods, or in the volume of primary tumours. We concluded that local invasion and spontaneous metastasis are usefull for the characterization of malignancy in experimental fibrosarcoma-like tumours. Since Fischer rat cells produced invasive and sometimes metastatic tumours before transfection, the present data do not show a rôle of immortalizing and transforming genes in the acquisition of invasiveness and metastatic capability.
The expression of Smad interacting protein-1 (SIP1; ZEB2) and the de novo expression of vimentin ... more 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 b-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.
Neuroblastoma is the most frequent extracranial solid tumor in children, showing remarkable clini... more Neuroblastoma is the most frequent extracranial solid tumor in children, showing remarkable clinical and genetic heterogeneity. To make further progress in understanding the genetic basis of neuroblastoma we have applied suppression subtractive hybridization for the identification of differentially expressed transcripts. We
Loss of expression of the intercellular adhesion molecule E-cadherin frequently occurs in invasiv... more Loss of expression of the intercellular adhesion molecule E-cadherin frequently occurs in invasive lobular breast carcinomas as a result of mutational inactivation. Expression patterns of E-cadherin and the molecules comprising the cytoplasmic complex of adherens junctions, alpha-, beta- and gamma-catenin, were studied in a series of 38 lobular breast carcinomas with known E-cadherin mutation status. The effect of loss of E-cadherin by mutational inactivation (or other mechanisms) on the expression of catenins was investigated. Complete loss of plasma membrane-associated E-cadherin expression was observed in 32 out of 38 invasive lobular carcinomas, for which in 21 cases a mutation was found in the extracellular domain of E-cadherin. In total, 15 frameshift mutations of small deletions or insertions, ranging from 1 to 41 bp, three non-sense mutations, and three splice mutations were identified. Mutations were scattered over the whole coding region and no hot spots could be detected. In all cases, simultaneous loss of E-cadherin and alpha- and beta-catenin expression was found; in 50 per cent of these cases, additional loss of gamma-catenin was observed. In six invasive lobular carcinomas, expression of both E-cadherin and catenins was retained. In none of these carcinomas was an E-cadherin mutation detected. Lobular carcinoma in situ adjacent to invasive lobular carcinoma showed simultaneous loss of E-cadherin and catenins in all the cases studied--remarkably, also, in four cases positive for E-cadherin and catenin expression in the invasive component. These results indicate that simultaneous loss of E-cadherin and alpha-, beta- and gamma-catenin may be an important step in the formation of lobular carcinoma in situ, as a precursor of invasive lobular breast cancer. Events additional to E-cadherin inactivation must be involved in the transition of lobular carcinoma in situ to invasive lobular carcinoma.
the genome of the non-hybrid SV40 progeny differed slightly from that of SV40 strain 776, there i... more the genome of the non-hybrid SV40 progeny differed slightly from that of SV40 strain 776, there is no reason to believe that, these cha.nges are causally related to the integration and excision phenomena.
Reduced expression of E-cadherin has been associated with loss of differentiation and/or increase... more Reduced expression of E-cadherin has been associated with loss of differentiation and/or increased invasiveness and metastatic ability in several types of neoplasms. Rare studies on thyroid tumors have shown minimal or absent expression in undifferentiated carcinomas and a variable degree of immunoreactivity/mRNA expression in follicular and papillary carcinomas. We studied immunohistochemically 2 follicular adenomas, 8 follicular carcinomas, 18 papillary carcinomas and 3 poorly differentiated carcinomas to evaluate E-cadherin expression. In 7 papillary carcinomas, lymph node metastases were also studied. The E-cadherin gene was analysed in 27 tumors by PCR/SSCP followed, whenever appropriate, by DNA sequencing. LOH at the E-cadherin locus was assessed in 16 tumors. Reduced and heterogeneous expression of E-cadherin was found in primary and metastatic papillary carcinomas, whereas follicular carcinomas showed moderate to strong homogeneous immunoreactivity, and poorly differentiated carcinomas showed no or very faint immunoreactivity. The only case harbouring a (missense type) mutation of the E-cadherin gene was a papillary carcinoma exhibiting immunoreactivity in the primary tumor as well as in metastasis. LOH was found in a follicular adenoma and in a poorly differentiated carcinoma without evidence of mutation in the remaining allele. Our results show that irreversible alterations (allele loss or mutation) of the E-cadherin gene are infrequent in thyroid tumors. The reduced and heterogeneous expression of E-cadherin in thyroid carcinomas, particularly of the papillary histotype, appears to reflect transcriptional regulation or post-transcriptional modulation rather than structural abnormalities.
Abberant activation of the process of epithelial-mesenchymal transition in cancer cells is a late... more Abberant activation of the process of epithelial-mesenchymal transition in cancer cells is a late event in tumor progression. A key inducer of this transition is the transcription factor Snail, which represses E-cadherin. We report that conditional expression of the human transcriptional repressor Snail in colorectal cancer cells induces an epithelial dedifferentiation program that coincides with a drastic change in cell morphology. Snail target genes control the establishment of several junctional complexes, intermediate filament networks, and the actin cytoskeleton. Modulation of the expression of these genes is associated with loss of cell aggregation and induction of invasion. Chromatin immunoprecipitation experiments showed that repression of selected target genes is associated with increased binding of Snail to their promoters, which contain consensus Snail-binding sites. Thus, Snail constitutes a master switch that directly represses the epithelial phenotype, resulting in malignant carcinoma cells.
Supplementary Figure 2 from E-Cadherin Regulates Human Nanos1, which Interacts with p120ctn and I... more Supplementary Figure 2 from E-Cadherin Regulates Human Nanos1, which Interacts with p120ctn and Induces Tumor Cell Migration and Invasion
Supplementary Methods, Materials and Figure Legends 1-2 from E-Cadherin Regulates Human Nanos1, w... more Supplementary Methods, Materials and Figure Legends 1-2 from E-Cadherin Regulates Human Nanos1, which Interacts with p120ctn and Induces Tumor Cell Migration and Invasion
Supplementary Table 2 from The Transcription Factor Snail Induces Tumor Cell Invasion through Mod... more Supplementary Table 2 from The Transcription Factor Snail Induces Tumor Cell Invasion through Modulation of the Epithelial Cell Differentiation Program
Supplementary Table 1 from The Transcription Factor Snail Induces Tumor Cell Invasion through Mod... more Supplementary Table 1 from The Transcription Factor Snail Induces Tumor Cell Invasion through Modulation of the Epithelial Cell Differentiation Program
The human 1p36 region is deleted in many different types of tumors, and so it probably harbors on... more The human 1p36 region is deleted in many different types of tumors, and so it probably harbors one or more tumor suppressor genes. In a Belgian neuroblastoma patient, a constitutional balanced translocation t(1;17)(p36.2;q11.2) may have led to the development of the tumor by disrupting or activating a gene. Here, we report the cloning of both translocation breakpoints and the identification of a novel gene that is disrupted by this translocation. This gene, named NBPF1 for Neuroblastoma BreakPoint Family member 1, belongs to a recently described gene family encoding highly similar proteins, the functions of which are unknown. The translocation truncates NBPF1 and gives rise to two chimeric transcripts of NBPF1 sequences fused to sequences derived from chromosome 17. On chromosome 17, the translocation disrupts one of the isoforms of ACCN1, a potential glioma tumor suppressor gene. Expression of the NBPF family in neuroblastoma cell lines is highly variable, but it is decreased in cell lines that have a deletion of chromosome 1p. More importantly, expression profiling of the NBPF1 gene showed that its expression is significantly lower in cell lines with heterozygous NBPF1 loss than in cell lines with a normal 1p chromosome. Meta-analysis of the expression of NBPF and ACCN1 in neuroblastoma tumors indicates a role for the NBPF genes and for ACCN1 in tumor aggressiveness. Additionally, DLD1 cells with inducible NBPF1 expression showed a marked decrease of clonal growth in a soft agar assay. The disruption of both NBPF1 and ACCN1 genes in this neuroblastoma patient indicates that these genes might suppress development of neuroblastoma and possibly other tumor types.
Proceedings of the National Academy of Sciences of the United States of America, Dec 1, 1989
Tumor necrosis factor (TNF) is cytotoxic for several transformed cell lines in vitro. In the pres... more Tumor necrosis factor (TNF) is cytotoxic for several transformed cell lines in vitro. In the presence of LiCI, the murine fibrosarcoma cell lines L929 and WEHI 164 done 13 became >10 times more sensitive to TNF-mediated cyto-
E-cadherin-mediated cell-cell adhesion is critical for naive pluripotency of cultured mouse embry... more E-cadherin-mediated cell-cell adhesion is critical for naive pluripotency of cultured mouse embryonic stem cells (mESCs). E-cadherin-depleted mESC fail to downregulate their pluripotency program and are unable to initiate lineage commitment. To further explore the roles of cell adhesion molecules during mESC differentiation, we focused on p120 catenin (p120ctn). Although one key function of p120ctn is to stabilize and regulate cadherin-mediated cell-cell adhesion, it has many additional functions, including regulation of transcription and Rho GTPase activity. Here, we investigated the role of mouse p120ctn in early embryogenesis, mESC pluripotency and early fate determination. In contrast to the E-cadherin-null phenotype, p120ctn-null mESCs remained pluripotent, but their in vitro differentiation was incomplete. In particular, they failed to form cystic embryoid bodies and showed defects in primitive endoderm formation. To pinpoint the underlying mechanism, we undertook a structure-...
Hyperactivation of the Wnt pathway is a common hallmark of many cancers. Deregulation of the path... more Hyperactivation of the Wnt pathway is a common hallmark of many cancers. Deregulation of the pathway is mostly due to mutations in the tumor suppressor gene Adenomatous Polyposis Coli (APC) or the transcriptional regulator of the Wnt pathway β-catenin (CTNNB1). Heterozygous germline mutations in the Mutation Cluster Region (MCR) of the APC gene cause Familial Adenomatous Polyposis (FAP), a condition characterized by multiple colorectal polyps, which over time become malignant. FAP patients also frequently suffer from extracolonic manifestations, such as Congenital Hypertrophy of the Retinal Pigment Epithelium (CHRPE), desmoid tumors and medulloblastoma. Despite many mouse models and the clear etiology of colorectal cancer and FAP, no drugs targeting the Wnt pathway have reached the clinic and there is a need for new genetic animal models. The recent TALEN (Transcription Activator Like Effector Nuclease) and CRISPR/Cas9 gene targeting technologies open the door for novel genetic canc...
Tumor necrosis factor (TNF), first described as a cytokine with tumor- necrotizing activity, is n... more Tumor necrosis factor (TNF), first described as a cytokine with tumor- necrotizing activity, is now known to be a pleiotropic molecule. The mo lecular mechanisms responsible for the cytotoxic activity of TNF on ma lignant cells are still largely unknown. In this study, we report that the protein kinase inhibitor Staurosporine (56 to 1500 UM i increases about 500 times
Abstract A specific deletion mutant of human adenovirus type 2 (Ad2) was detected when pools of w... more Abstract A specific deletion mutant of human adenovirus type 2 (Ad2) was detected when pools of wild-type Ad2 were grown at high multiplicity of infection in HeLa cells. This deletion mutant, designated dl-Ad2, was enriched when the defective Ad2-SV40 hybrids of the Ad2 ++ HEY population were cloned in monkey cells in the presence of an added excess of wild-type Ad2. Electron microscope heteroduplex analysis and restriction endonuclease examination established the Ad-specific nature of the dl-Ad2 DNA and revealed a single, homogeneous deletion of about 0.08 to 0.09 fractional genome length situated between 0.78 and 0.87 Ad2 map unit. This genome structure is very similar to that of several other incomplete adenoviruses already described. The deleted segment encompasses one of the four early genome regions of Ad2. dl-Ad2 particles are not infectious in both human and monkey cells, although the mutant DNA is replicated in these cell types. dl-Ad2 is able to interfere efficiently with SV40 DNA replication in coinfected monkey cells. Furthermore, virus populations could be cloned consisting exclusively of Ad2 ++ HEY hybrid viruses and dl-Ad2 “helper” viruses, indicating that dl-Ad2 can complement sufficiently for the large Ad2 DNA deletion in the Ad2 ++ HEY hybrid genomes.
The International Journal of Developmental Biology, 2010
During and after gastrulation, the neural axis in vertebrates is patterned along the antero-poste... more During and after gastrulation, the neural axis in vertebrates is patterned along the antero-posterior axis by the combined activity of signaling factors secreted in the neural ectoderm and the underlying mesoderm. These signals divide the neural axis into four major divisions: the forebrain, midbrain, hindbrain and spinal chord. Among the signals that pattern the neural axis, Wnts play a prominent role and many patterning genes have been found to be direct Wnt/ catenin target genes, including several homeobox domain-containing transcription factors. Here we show that HoxD1 and Irx3 are transcriptionally induced by the Wnt pathway during neurulation. Using induction in the presence of the translation blocking drug cycloheximide and chromatin immunoprecipitation assays, we confirm that HoxD1 and Irx3 are both direct Wnt target genes. In addition, we identified Crabp2 (cellular retinoic acid binding protein 2) as an indirect target that potentially links the activities of Wnt and retinoic acid during antero-posterior patterning.
Fischer rat cells before and after transfection with immortalizing and transforming genes produce... more Fischer rat cells before and after transfection with immortalizing and transforming genes produced tumours after s.c., i.p., or i.v. injection of cell suspensions and after s.c. implantation of cellular aggregates in the tail of syngeneic rats. Tumours were described histologically as fibrosarcoma-like. Virtually all tumours were considered macroscopically to be invasive because they adhered to the neighbouring tissues; in many tumours invasion was confirmed microscopically. All types of cells produced lung colonies (artificial metastases) after i.v. injection. Spontaneous metastases (from a primary tumour) were found with some tumours produced by cells before as well as after transfection. Differences in metastasis between various cell types could not be ascribed to variations in the periods of observation, in the minimum tumour-bearing periods, in the latency periods, or in the volume of primary tumours. We concluded that local invasion and spontaneous metastasis are usefull for the characterization of malignancy in experimental fibrosarcoma-like tumours. Since Fischer rat cells produced invasive and sometimes metastatic tumours before transfection, the present data do not show a rôle of immortalizing and transforming genes in the acquisition of invasiveness and metastatic capability.
The expression of Smad interacting protein-1 (SIP1; ZEB2) and the de novo expression of vimentin ... more 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 b-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.
Neuroblastoma is the most frequent extracranial solid tumor in children, showing remarkable clini... more Neuroblastoma is the most frequent extracranial solid tumor in children, showing remarkable clinical and genetic heterogeneity. To make further progress in understanding the genetic basis of neuroblastoma we have applied suppression subtractive hybridization for the identification of differentially expressed transcripts. We
Loss of expression of the intercellular adhesion molecule E-cadherin frequently occurs in invasiv... more Loss of expression of the intercellular adhesion molecule E-cadherin frequently occurs in invasive lobular breast carcinomas as a result of mutational inactivation. Expression patterns of E-cadherin and the molecules comprising the cytoplasmic complex of adherens junctions, alpha-, beta- and gamma-catenin, were studied in a series of 38 lobular breast carcinomas with known E-cadherin mutation status. The effect of loss of E-cadherin by mutational inactivation (or other mechanisms) on the expression of catenins was investigated. Complete loss of plasma membrane-associated E-cadherin expression was observed in 32 out of 38 invasive lobular carcinomas, for which in 21 cases a mutation was found in the extracellular domain of E-cadherin. In total, 15 frameshift mutations of small deletions or insertions, ranging from 1 to 41 bp, three non-sense mutations, and three splice mutations were identified. Mutations were scattered over the whole coding region and no hot spots could be detected. In all cases, simultaneous loss of E-cadherin and alpha- and beta-catenin expression was found; in 50 per cent of these cases, additional loss of gamma-catenin was observed. In six invasive lobular carcinomas, expression of both E-cadherin and catenins was retained. In none of these carcinomas was an E-cadherin mutation detected. Lobular carcinoma in situ adjacent to invasive lobular carcinoma showed simultaneous loss of E-cadherin and catenins in all the cases studied--remarkably, also, in four cases positive for E-cadherin and catenin expression in the invasive component. These results indicate that simultaneous loss of E-cadherin and alpha-, beta- and gamma-catenin may be an important step in the formation of lobular carcinoma in situ, as a precursor of invasive lobular breast cancer. Events additional to E-cadherin inactivation must be involved in the transition of lobular carcinoma in situ to invasive lobular carcinoma.
the genome of the non-hybrid SV40 progeny differed slightly from that of SV40 strain 776, there i... more the genome of the non-hybrid SV40 progeny differed slightly from that of SV40 strain 776, there is no reason to believe that, these cha.nges are causally related to the integration and excision phenomena.
Reduced expression of E-cadherin has been associated with loss of differentiation and/or increase... more Reduced expression of E-cadherin has been associated with loss of differentiation and/or increased invasiveness and metastatic ability in several types of neoplasms. Rare studies on thyroid tumors have shown minimal or absent expression in undifferentiated carcinomas and a variable degree of immunoreactivity/mRNA expression in follicular and papillary carcinomas. We studied immunohistochemically 2 follicular adenomas, 8 follicular carcinomas, 18 papillary carcinomas and 3 poorly differentiated carcinomas to evaluate E-cadherin expression. In 7 papillary carcinomas, lymph node metastases were also studied. The E-cadherin gene was analysed in 27 tumors by PCR/SSCP followed, whenever appropriate, by DNA sequencing. LOH at the E-cadherin locus was assessed in 16 tumors. Reduced and heterogeneous expression of E-cadherin was found in primary and metastatic papillary carcinomas, whereas follicular carcinomas showed moderate to strong homogeneous immunoreactivity, and poorly differentiated carcinomas showed no or very faint immunoreactivity. The only case harbouring a (missense type) mutation of the E-cadherin gene was a papillary carcinoma exhibiting immunoreactivity in the primary tumor as well as in metastasis. LOH was found in a follicular adenoma and in a poorly differentiated carcinoma without evidence of mutation in the remaining allele. Our results show that irreversible alterations (allele loss or mutation) of the E-cadherin gene are infrequent in thyroid tumors. The reduced and heterogeneous expression of E-cadherin in thyroid carcinomas, particularly of the papillary histotype, appears to reflect transcriptional regulation or post-transcriptional modulation rather than structural abnormalities.
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Papers by Frans van Roy