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135 records · Page 8Linked to original sources
PubMed2001

Hgfr/Met oncogene acts as target for gene amplification in DMBA-induced rat sarcomas: free chromatin fluorescence in situ hybridization analysis of amplicon arrays in homogeneously staining regions.

Analysis of chromosome rearrangements in tumors is an important means for revealing genetic pathways underlying tumorigenesis and tumor progression. In five of 17 DMBA-induced rat sarcomas, cytogenetic analysis had disclosed homogeneously staining regions (hsrs), which are generally accepted to be cytogenetic signs of gene amplification. Using comparative genomic hybridization (CGH), regional increases in DNA copy number of the proximal part of rat chromosome (RNO) 4 were detected in four of the tumors harboring hsrs. Amplification of the Hgfr/Met oncogene, located at RNO4q21.2, was detected by fluorescence in situ hybridization (FISH) in five tumors. In four of them, a number of flanking genes located in the close vicinity of Hgfr/Met, including Cav1 (q21.1), Wnt2 (q21.2-q21.3), and Cftr (q21.3), also were amplified, though amplification was seen in a lower fraction of the cells than was Hgfr/Met amplification. In the fifth tumor (BL150T), Hgfr/Met was amplified in all cells and was the sole amplified gene of those tested. In addition, the Hgfr/Met FISH signals in BL150T were tightly clustered and formed compact and intense spots compared with the signals seen in the other four tumors. Application of the free chromatin FISH technique to BL150T showed that the genomic Hgfr/Met probe stained the extended chromatin fibers of up to 1.5 Mb with an almost uninterrupted signal, indicating that the BL150T amplicon was build up solely of Hgfr/Met gene sequences. Our results suggest that the Hgfr/Met oncogene is the primary target for amplification in a subset of rat DMBA sarcomas.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed2002

Expression of ST7R (ST7-like, ST7L) in normal tissues and cancer.

We have recently cloned and characterized ST7R (ST7-like, ST7L), WNT3, WNT3A, WNT5B, WNT6, WNT7B, WNT8A, WNT8B, WNT10A, WNT10B, WNT11, WNT14, WNT14B/WNT15, NKD1, NKD2, ARHU/WRCH1, ARHV/WRCH2, and VANGL1/STB2 using bioinformatics, cDNA-PCR and RACE. ST7R is a paralog of tumor suppressor gene ST7 in the human genome. ST7R gene is clustered with WNT2B gene in human chromo-some 1p13 region, while ST7 gene is clustered with WNT2 gene in human chromosome 7q31 region. Multiple ST7R mRNAs (ST7R1-ST7R4) are transcribed due to alternative splicing. ST7R4 is divergent from ST7R1-ST7R3 in the C-terminal region. Here, we investigated expression of ST7R mRNAs in normal human tissues and human cancer. Northern blot analysis with S7S1 probe corresponding to ST7R1, ST7R2 and ST7R3 isoforms detected 4.2 kb ST7R mRNA in various normal tissues, and also large amounts of 2.2-2.4 kb ST7R mRNAs in testis. Northern blot analysis with S7S4 probe corresponding to ST7R4 isoform detected 2.0 kb ST7R mRNA in testis. Expression of ST7R mRNAs in human cancer was next investigated using cDNA-PCR. Although ST7R mRNAs were almost ubiquitously expressed in 7 gastric cancer cell lines, expression levels of ST7R mRNAs were relatively lower in TMK1 cells. ST7R mRNAs were expressed in most cases of primary gastric cancer, and were up-regulated in 2 out of 10 cases of primary gastric cancer. This is the first report on expression analyses on ST7R.

Alternative Splicing↗
PubMed2002

Up-regulation of WNT8B mRNA in human gastric cancer.

WNT - beta-catenin - TCF signaling pathway is activated by Xenopus wnt-8 (Xwnt-8) during Xenopus early development, and dysregulated activation of beta-catenin - TCF signaling pathway in mammalian cells leads to carcinogenesis. We have previously cloned and characterized human WNT8A, one of human orthologues of Xwnt-8. Here, we cloned and characterized human WNT8B by using bioinformatics, cDNA-PCR, and RACE. WNT8B gene of about 23-kb in size consisted of six exons, and encoded a 351-amino-acid polypeptide with the N-terminal signal peptide and two N-linked glycosylation sites. C-terminal region of WNT8B, WNT8A, WNT2, and WNT2B were longer than that of other human WNTs. Thirty-five nucleotide changes between WNT8B isolated by us and WNT8B isolated by another group resulted in Gly230Ala and Arg284Leu amino-acid substitutions. Gly230 and Arg284 of WNT8B were conserved in WNT8A. Gly230-Arg284 WNT8B allele was also identified in human genome draft sequences AL133352.10, AL359759.18, and human EST BF732616. These results indicate that the Gly230-Arg284 WNT8B cDNA isolated in this study is derived from the more common WNT8B allele. WNT8B mRNAs of 4.4- and 3.5-kb in size were weakly detected in a colorectal cancer cell line SW480, but were undetectable in any normal human tissues by using Northern blot analyses. WNT8B was significantly up-regulated in gastric cancer cell lines KATO-III (signet-ring cell carcinoma) and MKN45 (poorly differentiated adenocarcinoma), and also in 5 out of 10 cases of primary gastric cancer. WNT8B might play key roles in gastric cancer through activation of the beta-catenin - TCF signaling pathway.

Alleles↗
PubMed2002

Expression and regulation of WNT5A and WNT5B in human cancer: up-regulation of WNT5A by TNFalpha in MKN45 cells and up-regulation of WNT5B by beta-estradiol in MCF-7 cells.

WNT signaling pathway plays key roles in carcinogenesis and embryogenesis, and WNT signaling molecules are potent targets for diagnosis, prevention and treatment of cancer as well as for regenerative medicine or tissue engineering. We have so far cloned and characterized human WNT2B/WNT13, WNT3, WNT3A, WNT5B, WNT6, WNT7B, WNT8A, WNT8B, WNT10A, WNT10B, WNT11, WNT14 and WNT14B/WNT15 using bioinformatics and cDNA-PCR. We have also reported frequent up-regulation of WNT2 and WNT5A in primary gastric cancer, which is probably due to cancer-stromal interaction. Here, expression and regulation of WNT5A and WNT5B in human cancer were investigated. WNT5A was relatively highly expressed in TE6 and TE10 among 12 esophageal cancer cell lines, and WNT5B was expressed in the majority of esophageal cancer cell lines. Among 7 pancreatic cancer cell lines, WNT5A was up-regulated in Hs700T, and WNT5B in PANC-1. WNT5A, but not WNT5B, was up-regulated by TNFalpha in MKN45 cells derived from gastric cancer. WNT5B, but not WNT5A, was up-regulated by beta-estradiol in MCF-7 cells derived from breast cancer. WNT5A and WNT5B were expressed together in 5 embryonal tumor cell lines, and were slightly down-regulated by all-trans retinoic acid in NT2 cells. Up-regulation of WNT5A and WNT5B in several types of human cancer expressing FZD5 might lead to more malignant phenotype through activation of the beta-catenin - TCF pathway.

Animals↗
PubMed2002

Molecular genetics and animal models in autistic disorder.

Autistic disorder is a behavioural syndrome beginning before the age of 3 years and lasting over the whole lifetime. It is characterised by impaired communication, impaired social interactions, and repetitive interests and behaviour. The prevalence is about 7/10,000 taking a restrictive definition and more than 1/500 with a broader definition, including all the pervasive developmental disorders. The importance of genetic factors has been highlighted by epidemiological studies showing that autistic disorder is one of the most genetic neuropsychiatric diseases. The relative risk of first relatives is about 100-fold higher than the risk in the normal population and the concordance in monozygotic twin is about 60%. Different strategies have been applied on the track of susceptibility genes. The systematic search of linked loci led to contradictory results, in part due to the heterogeneity of the clinical definitions, to the differences in the DNA markers, and to the different methods of analysis used. An oversimplification of the inferred model is probably also cause of our disappointment. More work is necessary to give a clearer picture. One region emerges more frequently: the long arm of chromosome 7. Several candidate genes have been studied and some gave indications of association: the Reelin gene and the Wnt2 gene. Cytogenetical abnormalities are frequent at 15q11-13, the region of the Angelman and Prader-Willi syndrome. Imprinting plays an important role in this region, no candidate gene has been identified in autism. Biochemical abnormalities have been found in the serotonin system. Association and linkage studies gave no consistent results with some serotonin receptors and in the transporter, although it seems interesting to go further in the biochemical characterisation of the serotonin transporter activity, particularly in platelets, easily accessible. Two monogenic diseases have been associated with autistic disorder: tuberous sclerosis and fragile X. A better knowledge of the pathophysiology of these disorders can help to understand autism. Different other candidate genes have been tested, positive results await replications in other samples. Animal models have been developed, generally by knocking out the different candidate genes. Behaviour studies have mainly focused on anxiety and learning paradigms. Another group of models results from surgical or toxic lesions of candidate regions in the brain, in general during development. The tools to analyse these animals are not yet standardised, and an important effort needs to be undertaken.

Animals↗
PubMed2002

Molecular cloning and characterization of mouse St7r (St7-like, St7l).

Human ST7R (ST7-like, ST7L) is a paralog of tumor suppressor gene ST7 in the human genome. ST7R gene is clustered with WNT2B gene in human chromosome 1p13, while ST7 gene is clustered with WNT2 gene in human chromosome 7q31. Here, we have cloned mouse ortholog of human ST7R using bioinformatics and cDNA-PCR. Mouse St7r was found to encode 559 amino-acid polypeptide. Mouse St7r showed 90.7% total-amino-acid identity with human ST7R isoform 4 (ST7R4), and 71.6% total-amino-acid identity with human ST7 and mouse St7. Three tyrosine-phosphorylation sites as well as ST7R homologous domains (S7H1, S7H2, and S7H3) were conserved among mouse St7r, human ST7R, mouse St7, and human ST7. Leucine zipper domain of mouse St7r was conserved in human ST7R, but not in mouse St7 and human ST7. Mouse St7r was expressed almost ubiquitously in adult mouse tissues and also in mouse embryos. Although mouse genome draft sequence including mouse St7r gene has not yet been identified, rat genome draft sequence AC106372.1 was found to include rat St7r gene as well as rat Wnt2b gene. These results indicate evolutional conservation of ST7R-WNT2B gene cluster. This is the first report on molecular cloning and initial characterization of mouse St7r.

Amino Acid Sequence↗
PubMed2001

WNT2B2 mRNA, up-regulated in primary gastric cancer, is a positive regulator of the WNT- beta-catenin-TCF signaling pathway.

Genetic alterations of WNT signaling molecules lead to carcinogenesis through activation of the beta-catenin-TCF signaling pathway. We have previously cloned and characterized WNT2B/WNT13 gene on human chromosome 1p13, which is homologous to proto-oncogene WNT2 on human chromosome 7q31. WNT2B1 and WNT2B2 mRNAs, generated from the WNT2B gene due to alternative splicing of the alternative promoter type, encode almost identical polypeptides with divergence in the N-terminal region. WNT2B2 mRNA rather than WNT2B1 mRNA is preferentially expressed in NT2 cells with the potential of neuronal differentiation. Here, we describe our investigations of expression of WNT2B mRNAs in various types of human primary cancer. Matched tumor/normal expression array analysis revealed that WNT2B mRNAs were significantly up-regulated in 2 of 8 cases of primary gastric cancer. WNT2B2 mRNA rather than WNT2B1 mRNA was found to be preferentially up-regulated in a case of primary gastric cancer (signet ring cell carcinoma). Function of WNT2B1 mRNA and that of WNT2B2 mRNA were investigated by using Xenopus axis duplication assay. Injection of synthetic WNT2B1 mRNA into the ventral marginal zone of fertilized Xenopus eggs at the 4-cell stage did not induce axis duplication. In contrast, ventral injection of synthetic WNT2B2 mRNA induced axis duplication in 90% of embryos (complete axis duplication, 24%). These results strongly suggest that WNT2B2 up-regulation in some cases of gastric cancer might lead to carcinogenesis through activation of the beta-catenin-TCF signaling pathway.

Animals↗
PubMed1994

Oncogene amplification in urothelial cancers with p53 gene mutation or MDM2 amplification.

BACKGROUND: Previously, p53 (also known as TP53) gene mutations have been shown to be frequently detected in highly malignant urothelial cancers. Evidence has been accumulating that the disruption of the normal function of p53 may lead to genomic instability, including predisposition to gene amplification. Furthermore, the normal function of p53 may be abrogated by MDM2 (murine double minute-2) gene amplification in some human tumors. PURPOSE: Our purpose was to investigate the relationship between protooncogene amplification and p53 alteration in urothelial cancers by examining the existence of amplification of MDM2 and 14 other protooncogenes in 50 urothelial tumors in which p53 gene status was known. METHODS: We analyzed gene amplification by Southern-blot analysis in 50 urothelial cancer specimens. These tumors were previously examined for p53 mutations by polymerase chain reaction-single-strand conformation analysis, and 17 tumors contained p53 mutations. RESULTS: Two high-grade advanced tumors (4%) without p53 mutation harbored MDM2 amplification with concurrent int-2 gene amplification. As for other genes, amplification was detected for int-2 (also known as WNT2) (seven [14%] of 50), erbB-2 (also known as ERBB2) (three [6%] of 50), N-ras (also known as NRAS) (one [2%] of 50), L-myc (also known as MYCL1) (one [2%] of 50), and raf-1 (also known as RAF1) (one [2%] of 50). The amplification of at least one gene examined was observed in 11 (22%) of 50 tumors. The presence of p53 mutations was not significantly associated with the occurrence of gene amplification, since the amplification was detected in six (35%) of 17 tumors with p53 mutations and in five (15%) of 33 tumors without p53 mutations. However, eight (73%) of 11 tumors with proto-oncogene amplification harbored p53 mutations or MDM2 amplification. CONCLUSIONS AND IMPLICATIONS: A subset of advanced urothelial cancers without p53 mutations may harbor MDM2 amplification. This finding should be taken into account when adopting p53 alteration as a marker of aggressiveness in urothelial cancers. Although the abrogation of normal p53 function may be one of the key steps to protooncogene amplification, the data further indicate that the predisposition to gene amplification in urothelial cancers was not determined by the presence of p53 alteration alone.

Blotting, Southern↗
PubMed2003

Beta-catenin abnormalities and associated insulin-like growth factor overexpression are important in phyllodes tumours and fibroadenomas of the breast.

The aim of this study was to assess the expression of IGF-I and IGF-II in phyllodes tumours and fibroadenomas and to see if there is any correlation between nuclear beta-catenin expression and IGF-I and IGF-II expression in these tumours. In a previous study, it has been shown that Wnt signalling is important in the pathogenesis of phyllodes tumours of the breast. Epithelial Wnt5a overexpression and stromal Wnt2 overexpression were associated with abnormal, nuclear localization of beta-catenin in the stromal cells of these tumours. However, not all tumours with beta-catenin accumulation showed Wnt overexpression. One other possible cause of beta-catenin accumulation is overexpression of insulin-like growth factors (IGFs), as both IGF-I and IGF-II have been shown to stabilize beta-catenin. In this study, 30 fibroadenomas of the breast were assessed for beta-catenin expression using immunohistochemistry and the results were compared with previous data from 119 phyllodes tumours. In situ hybridization was used to assess IGF-I and IGF-II expression in 23 phyllodes tumours and 16 fibroadenomas. Nineteen phyllodes tumours (83%) showed widespread overexpression of IGF-II and 5/23 (22%) showed widespread overexpression of IGF-I. IGF-I expression correlated with nuclear beta-catenin staining in phyllodes tumours. Malignant phyllodes tumours showed no or little IGF-I expression. There was a degree of nuclear beta-catenin expression in the stroma (weak in 33%, moderate in 27%, and strong in 40%) in all fibroadenomas and nuclear beta-catenin staining correlated with IGF-I overexpression. Extensive IGF-II overexpression was also found in the majority of fibroadenomas (12/16). These results support the hypothesis that IGF-I and IGF-II overexpression may be important in the pathogenesis of fibroepithelial neoplasms of the breast and that IGF-I overexpression is likely to be contributing to the nuclear beta-catenin localization observed in the tumours.

Breast Neoplasms↗