Chromosome localization of the human oncogene INT1 to 12q13 by in situ hybridization

Contactin 1: An Important and Emerging Oncogenic Protein Promoting Cancer Progression and Metastasis

Even with recent progress, cancer remains the second leading cause of death, outlining a need to widen the current understanding on oncogenic factors. Accumulating evidence from recent years suggest Contactin 1 (CNTN1)'s possession of multiple oncogenic activities in a variety of cancer types. CNTN1 is a cell adhesion molecule that is dysregulated in many human carcinomas and plays important roles in cancer progression and metastases. Abnormalities in CNTN1 expression associate with cancer progression and poor prognosis. Mechanistically, CNTN1 functions in various signaling pathways frequently altered in cancer, such as the vascular endothelial growth factor C (VEGFC)-VEGF receptor 3 (VEFGR3)/fms-related tyrosine kinase 4 (Flt4) axis, phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT), Notch signaling pathway and epithelial-mesenchymal transition (EMT) process. These oncogenic events are resulted via interactions between tumor and stroma, which can be contributed by CNTN1, an adhesion protein. CNTN1 expression in breast cancer correlates with the expression of genes functioning in cancer-stroma interactions and skeletal system development. Evidence supports that CNTN1 promotes cancer-stromal interaction, resulting in activation of a complex network required for cancer progression and metastasis (bone metastasis for breast cancer). CNTN1 inhibitions has been proven to be effective in experimental models to reduce oncogenesis. In this paper, we will review CNTN1's alterations in cancer, its main biochemical mechanisms and interactions with its relevant cancer pathways.

Hear the Wnt Ror: how melanoma cells adjust to changes in Wnt

The interplay between canonical and non-canonical Wnt pathways in development and tumorigenesis is tightly regulated. In this review we will describe the yin and the yang of canonical and non-canonical Wnt signaling pathways during melanocyte development, and melanoma genesis. Canonical Wnt signaling, represented by Wnts such as Wnt1 and Wnt3A, signals via beta-catenin to promote melanocyte differentiation and tumor development. Non-canonical Wnt signaling, specifically Wnt5A, regulates canonical pathways, and signals to induce melanoma metastasis. This review will focus on the role of Wnt5A during melanoma progression, and its relationship to canonical Wnt signaling.

Localization in man of fifteen DNA sequences within the chromosome segment 13q12-q22

Fifteen human chromosome 13 specific DNA fragments, isolated from a lambda phage genomic library, were localized within the segment 13q12-q22. One was mapped to 13q12.1-q12.2, three to 13q12.3-q13.1, one to 13q14,1-q14.2, five to 13q14.1-q21.1, one to 13q21.1-q21.2, two to 13q21.2, and one to 13q22.1, and one to 13q22. The localization was performed by hybridization to Southern blots of a panel of human cell lines with overlapping deletions in 13q, and for three probes also by in situ hybridization to metaphase chromosomes.

Anti-sense morpholino oligonucleotide assay shows critical involvement for NF-kappaB activation in the production of Wnt-1 protein by HepG2 cells: oncology implications

The link of proto-oncogenic protein Wnt-1 production with NF-kappaB activation has been functionally demonstrated in PC12 cells, a rat pheochromocytoma cell line of neural crest lineage, while it is not yet verified in human cells. The link can be indirectly supported in our previous report that functional proteomics identifies enhanced expression of NF-kappaB-associated Wnt-1 production in human hepatocellular carcinoma tissues. This study aimed to further validate this link in human cells using anti-sense strategy. The effects of sequence-specific anti-sense morpholino oligonucleotides (ONs) targeting against pre-mRNA sequences of human p50 and p65 subunits of NF-kappaB as well as Wnt-1 genes were investigated. It revealed that all the three morpholino ONs inhibited NF-kappaB activation in human hepatoblastoma cell line HepG2 cells along with decreased Wnt-1 production. Chromatin immunoprecipitation assay ascertained the direct binding of NF-kappaB-p50 to the Wnt-1 promoter. Additionally, anti-P50 and anti-P65 morpholino ONs also repressed the phosphorylation of Ikappa Balpha which temporarily correlated with the inhibition of NF-kappaB activation accompanied by decreased Wnt-1 production by HepG2 cells. In summary, NF-kappaB activation is critically involved in the production of Wnt-1 by HepG2 cells. These results may have important oncology implications in treating patients with NF-kappaB-associated Wnt-1-producing cancers.

Activation of Wnt signaling rescues neurodegeneration and behavioral impairments induced by beta-amyloid fibrils

Alzheimer's disease (AD) is a progressive neurodegenerative disorder, which is probably caused by the cytotoxic effect of the amyloid beta-peptide (Abeta). We report here molecular changes induced by Abeta, both in neuronal cells in culture and in rats injected in the dorsal hippocampus with preformed Abeta fibrils, as an in vivo model of the disease. Results indicate that in both systems, Abeta neurotoxicity resulted in the destabilization of endogenous levels of beta-catenin, a key transducer of the Wnt signaling pathway. Lithium chloride, which mimics Wnt signaling by inhibiting glycogen synthase kinase-3beta promoted the survival of post-mitotic neurons against Abeta neurotoxicity and recovered cytosolic beta-catenin to control levels. Moreover, the neurotoxic effect of Abeta fibrils was also modulated with protein kinase C agonists/inhibitors and reversed with conditioned medium containing the Wnt-3a ligand. We also examined the spatial memory performance of rats injected with preformed Abeta fibrils in the Morris water maze paradigm, and found that chronic lithium treatment protected neurodegeneration by rescuing beta-catenin levels and improved the deficit in spatial learning induced by Abeta. Our results are consistent with the idea that Abeta-dependent neurotoxicity induces a loss of function of Wnt signaling components and indicate that lithium or compounds that mimic this signaling cascade may be putative candidates for therapeutic intervention in Alzheimer's patients.

The Wnts

SUMMARY

The Wnt genes encode a large family of secreted protein growth factors that have been identified in animals from hydra to humans. In humans, 19 WNT proteins have been identified that share 27% to 83% amino-acid sequence identity and a conserved pattern of 23 or 24 cysteine residues. Wnt genes are highly conserved between vertebrate species sharing overall sequence identity and gene structure, and are slightly less conserved between vertebrates and invertebrates. During development, Wnts have diverse roles in governing cell fate, proliferation, migration, polarity, and death. In adults, Wnts function in homeostasis, and inappropriate activation of the Wnt pathway is implicated in a variety of cancers.

Neurogenetics of the cerebellar system

The development of the cerebellum occurs in four basic steps. During the first epoch, genes that mark the cerebellar territory are expressed in a restricted pattern along the anterioposterior axis of the embryo. In the second, an embryonic region termed the rhombic lip generates precursors of the granule cell population of the cerebellar cortex, and the lateral pontine nucleus and olivary nucleus of the brain stem. In the third period, the program of neurogenesis of the granule neuron gives rise to the formation of the fundamental layers of the cerebellum and to the pattern of foliation. Concomitantly, programs of gene expression define the principal neuronal classes, the granule cell and Purkinje cell, that will establish the cerebellar circuitry in the postnatal period. Understanding the molecular mechanisms underlying these steps of development is likely to yield important insights into malformations such as Joubert syndrome.

Analysis of 148 kb of Genomic DNA Around the wnt1 Locus of Fugu rubripes

The analysis of the sequence of ∼150 kb of a genomic region corresponding to the wnt1 gene of the Japanese pufferfishFugu rubripes confirms the compact structure of the genome. Fifteen genes were found in this region, and 26.6% of the analyzed sequence is coding sequence. With an average intergenic distance of <5 kb, this gene density is comparable to that ofCaenorhabditis elegans. The compactness of this region corresponds to the reduction of the overall size of the genome, consistent with the conclusion that the gene number in Fuguand human genomes is approximately the same. Eight of the genes have been mapped in the human genome and all of them are found in the chromosomal band 12q13, indicating a high degree of synteny in both species, Fugu and human. Comparative sequence analysis allows us to identify potential regulatory elements for wnt1 andARF3, which are common to fish and mammals.

[The sequence data described in this paper have been submitted to GenBank under accession no. AF056116.]

Co-amplification and overexpression of CDK4, SAS and MDM2 occurs frequently in human parosteal osteosarcomas

Amplification of genes in the 12q13-15 region occurs frequently in several malignancies including osteosarcoma. The products of these amplified genes are thought to provide cancer cells with a selective growth advantage; however, the specific gene(s) driving this amplicon is unknown. We have previously shown that the SAS gene is amplified in most parosteal osteosarcomas. In this study we analysed additional putative growth regulatory genes in this chromosomal region in 24 primary osteosarcoma specimens. CDK4 and SAS were coamplified in 6/6 parosteal tumors, and MDM2 was also amplified in 4/5 parosteal cases. In comparison, amplification occurred in only 2/16 classical intramedullary osteosarcomas and involved the SAS gene. Each amplified gene had a correspondingly elevated mRNA level. Four high grade intramedullary tumors had elevated mRNA expression of SAS, but did not exhibit gene amplification. Gene amplification/overexpression was not associated with metastatic disease and did not change markedly with tumor progression, as evidenced by analysis of sequential tumor specimens from eight patients. Three other genes in the 12q13-15 region (CDK2, WNT1 and WNT10b) were not amplified in any of the tumors. The different patterns of gene amplification and overexpression of CDK4, SAS and MDM2 in parosteal and intramedullary osteosarcomas may help explain the disparity in the biological behaviour of these two types of osteosarcoma.

Isolation of two novel WNT genes, WNT14 and WNT15, one of which (WNT15) is closely linked to WNT3 on human chromosome 17q21

The Wnt gene family consists of at least 15 structurally related genes that encode secreted extracellular signaling factors. Wnt proteins function in a range of critical developmental processes in both vertebrates and invertebrates and are implicated in regulation of cell growth and differentiation in certain adult mammalian tissues, including the mammary gland. We have isolated a number of WNT sequences from human genomic DNA, two of which, designated WNT14 and WNT15, represent novel members of the Wnt gene family. We also isolated WNT sequences from human mammary cDNA and present evidence that WNT13 is expressed in human breast tissue, in addition to those previously described. WNT14 and WNT15 appear to have originated from an ancestral branch of the Wnt gene family that also includes the Wnt9 sequences found in jawless and cartilaginous fishes. A Wnt14 cDNA was also isolated from chicken and a partial Wnt15 sequence from mouse. We show that human WNT14 maps to chromosome 1 and that WNT15 maps distal to BRCA1 on chromosome 17q21, where it lies within 125 kb of another WNT family member, WNT3.

Characterization of the 12q13-15 amplicon in soft tissue tumors

Amplification of the genes MDM2, SAS, and CDK4, all located on the long arm of chromosome 12, has recently been demonstrated in human soft tissue tumors. To determine the extent of the amplification unit, we examined 16 soft tissue tumor samples, including pleomorphic liposarcoma, malignant fibrous histiocytoma (MFH), and atypical lipoma, by Southern blot analysis using 13 chromosome 12 probes. All tumors had previously been shown to have 3- to 20-fold amplification of MDM2. In five samples, all MFH, only MDM2 was amplified, whereas in the remaining 11 samples, two to five additional genes were amplified. The amplicon included markers both proximal and distal to MDM2, but was in all but one atypical lipoma confined to the chromosome region 12q13-15. Discontinuous amplicons were found in two of the tumors. This study indicates that MDM2, or possibly an as-yet-unidentified gene in its proximity, is the target gene of the 12q13-15 amplification in soft tissue tumors.

Cytogenetic findings in 19 malignant bone tumors

BACKGROUND

The majority of karyotypes observed in osteosarcomas (OS) and chondrosarcomas (CS) are complex. Specific chromosomal abnormalities have not yet been characterized in either tumor except for a ring chromosome in parosteal OS. The purpose of this study was to determine recurrent chromosomal abnormalities and establish a possible correlation between the cytogenetic changes and the pathologic findings.

METHODS

Ten OS and nine CS were cytogenetically analyzed. Tumor samples were obtained from patients having a resection or incisional biopsy. Cytogenetic study of short term cell cultures included harvesting and G-banding, which were performed by routine methodologies.

RESULTS

Clonal abnormalities were observed in six OS and six CS. Modal chromosome numbers ranged from near diploid to near tetraploid in both types of tumors. The structural rearrangements observed in OS involved mostly chromosomes 1, 2, 6, 12, and 17. Nonreciprocal translocations were the most frequent event. Two OS had a single clonal abnormality involving 11p15 and 14q32, respectively. Double minute chromosomes were observed in three cases. In CS, the most frequent structural abnormalities were nonreciprocal translocations and deletions involving numerous chromosomes. Rearrangements of 1p together with other abnormalities were observed in four CS.

CONCLUSIONS

The karyotypes were usually complex consisting of numerical and structural changes, particularly in high grade tumors. Rearrangements of 11p15 and 14q32 in OS and possibly 1p in CS were found as primary cytogenetic aberrations. Cytogenetic analysis in more cases of OS and CS together with molecular studies are necessary to characterize further the consistent genetic changes in these tumors.

MDM2 gene amplification correlates with ring chromosome in soft tissue tumors

The human homolog of the murine double minute type 2 gene (MDM2) has been cloned and mapped to 12q13-14. The gene presumably functions as a cellular regulator and mediator of TP53 function. Amplification of the MDM2 gene has recently been observed in soft tissue sarcoma and in osteosarcoma. We studied MDM2 amplification in a series of 94 mesenchymal tumors and found 3-20-fold amplification in 20 tumors: in 10 of 49 malignant fibrous histiocytomas (MFH), in 1 of 2 pleomorphic liposarcomas, in 6 of 7 atypical lipomas, and in 3 of 12 typical lipomas. Normal hybridization patterns were detected in all 16 myxoid liposarcomas, in all 3 leiomyosarcomas, and in all 5 leiomyomas studied. The MDM2 amplification correlated with the presence of marker ring chromosomes; of the 10 MFH with MDM2 amplification, 5 had ring chromosomes, compared to 4 of 39 without MDM2 amplification, and all 9 liposomas with MDM2 amplification had ring chromosomes, in 5 of the tumors as the sole karyotypic anomaly. The correlation between ring chromosomes and MDM2 gene amplification indicates that the marker rings of MFH and of atypical lipoma often harbor genetic material derived from chromosome 12.

Translocation (12;14)(q13;q32) in myelodysplastic syndrome

We report a patient diagnosed with refractory anemia with excess blasts in transformation (RAEB-t) who underwent an evolution to a nonlymphocytic acute leukemia (ANLL-M5a). Initial cytogenetic study showed a diploid karyotype; however, when ANLL-M5a was diagnosed, the bone marrow (BM) cells showed a t(12;14)(q13;q32), which to our knowledge has not been described previously in a myelodysplastic syndrome (MDS).

12q13 abnormality in rhabdomyosarcoma. A nonrandom occurrence?

We describe two cases of rhabdomyosarcoma with a translocation involving 12q13 as the primary cytogenetic abnormality. Literature review of 35 cases has identified 3 other cases with this abnormality, and we speculate that this may be another nonrandom rearrangement in rhabdomyosarcoma.

Involvement of 3p deletions in sporadic and hereditary forms of renal cell carcinoma

Deletions of the short arm of chromosome 3 and associated allele losses have been reported in the majority of sporadic renal cell carcinomas (RCC). On the basis of the combined cytogenetic and molecular data, it is reasonable to assume that a putative RCC locus, which contributes to tumor development by its loss, is located telomerically of the D3F15S2 site. Using H3E4, a D3F15S2-specific probe, we have isolated a cDNA clone (cl.4-2), and a sequence comparison revealed that the cDNA clone corresponds to the human acyl-peptide hydrolase gene. The gene is fairly universally expressed, but in RCC biopsies its expression is severely reduced, compared to the normal kidney. Cl.4-2 was used for in situ hybridization on metaphase chromosomes prepared from an Epstein-Barr virus (EBV) transformed lymphoblastoid cell line, derived from a t(3;8) (p14.2;q24.1) carrying member of the RCC family described by Cohen et al. in 1979 (N Engl J Med: 301:592-595). Carriers of this translocation regularly develop RCC by middle age. We now report that D3F15S2 is localized on the telomeric side of the constitutional breakpoint, in 3p21. The region of 3p affected by this familial translocation is thus not identical with the region of 3p most frequently deleted in sporadic RCC.

Unusual t(3;12)(q28;q13) in childhood acute lymphoblastic leukemia

In this article we report a case of a 7-year-old boy affected by acute lymphoblastic leukemia of the common type. Bone marrow examination at diagnosis showed a reciprocal translocation between the long arm of chromosome 3 and the long arm of chromosome 12. This previously unpublished translocation is discussed and compared to the findings in the current literature.

GLI3 encodes a 190-kilodalton protein with multiple regions of GLI similarity

The GLI oncogene, discovered by virtue of its amplification in human tumors, encodes a sequence-specific DNA-binding protein containing five zinc fingers. We have now characterized one member of a family of GLI-related zinc finger genes. A previously identified fragment of GLI3 genomic DNA was used to localize GLI3 to chromosome 7p13 and to isolate cDNA clones. Sequence analysis of these clones and identification of the GLI3 protein by using polyclonal antisera demonstrated that GLI3 encodes a protein of 1,596 amino acids and an apparent molecular mass of 190 kilodaltons. Amino acid sequence comparison with GLI demonstrated seven regions of similarity (53 to 88% identity), with the zinc fingers representing the most similar region. Furthermore, when produced in vitro, the GLI3 protein bound specifically to genomic DNA fragments containing GLI-binding sites. Amino acid sequence comparison with the product of another member of the GLI family, the Drosophila segment polarity gene cubitus interruptus Dominant, revealed additional similarity that was not shared with GLI. These studies suggest that the GLI-related genes encode a family of DNA-binding proteins with related target sequence specificities. In addition, sequence similarity aside from the zinc finger region suggests that other aspects of function are shared among the members of this gene family.

GLI3 encodes a 190-kilodalton protein with multiple regions of GLI similarity

The GLI oncogene, discovered by virtue of its amplification in human tumors, encodes a sequence-specific DNA-binding protein containing five zinc fingers. We have now characterized one member of a family of GLI-related zinc finger genes. A previously identified fragment of GLI3 genomic DNA was used to localize GLI3 to chromosome 7p13 and to isolate cDNA clones. Sequence analysis of these clones and identification of the GLI3 protein by using polyclonal antisera demonstrated that GLI3 encodes a protein of 1,596 amino acids and an apparent molecular mass of 190 kilodaltons. Amino acid sequence comparison with GLI demonstrated seven regions of similarity (53 to 88% identity), with the zinc fingers representing the most similar region. Furthermore, when produced in vitro, the GLI3 protein bound specifically to genomic DNA fragments containing GLI-binding sites. Amino acid sequence comparison with the product of another member of the GLI family, the Drosophila segment polarity gene cubitus interruptus Dominant, revealed additional similarity that was not shared with GLI. These studies suggest that the GLI-related genes encode a family of DNA-binding proteins with related target sequence specificities. In addition, sequence similarity aside from the zinc finger region suggests that other aspects of function are shared among the members of this gene family.

Cytogenetic findings in nine leiomyomas of the uterus

Chromosomal analysis of nine benign leiomyomas of the uterus after short-term culture showed karyotypic abnormalities in four cases. All four exhibited multiple chromosome changes, including three cases characterized by complex chromosome rearrangements involving a number of chromosomes. Among others, these rearrangements included a translocation between chromosomes 12 and 14 in one case, a deletion of chromosome 7q in two cases, and both del(7q) and a complex translocation involving chromosomes 12 and 14 in another case. These results confirm the involvement of chromosomes 7, 12, and 14 in leiomyomas and indicate that benign tumors can also be characterized by complex cytogenetic changes.

Complex cytogenetic changes in benign neoplasms. Report of six lipomas

We report the detailed cytogenetic findings from short-term cultures of six lipomas with complex chromosomal abnormalities. In all six cases, the abnormality occurred in two stages; an initial inversion, translocation, or insertion of the involved chromosome(s) followed by a subsequent rearrangement of the resultant derivative chromosome(s). A striking feature of these rearrangements was the consistent involvement of bands q13 - q14 on chromosome 12 in all the abnormalities. This region has been shown to be specifically rearranged in most of the lipomas studied. The other chromosomes involved in the rearrangements were chromosomes 1 in four cases, 5 and 9 in two cases each, and 2, 3, 4, 7, and 10 in one case each. Our findings and published findings show that, with a few exceptions, benign tumors that were previously considered cytogenetically normal, are characterized not only by specific numerical and structural changes but may also contain complex chromosome rearrangements that are generally considered a hallmark of advanced malignancy. In benign tumors, this suggests that the genes at the region of the breakpoints may represent proliferation-related genes or that benign tumors with such complex aberrations represent neoplasms potentially capable of undergoing transformation to malignancy, or both.

The INT1 oncogene is not rearranged or amplified in lipomas with structural chromosomal abnormalities of 12q13-15

DNA from nine different solitary subcutaneous lipomas, all with clonal abnormalities affecting the chromosome segment 12q13-15, was examined for rearrangement or amplification of a human INT1 gene sequence. INT1 is a putative oncogene that has been localized to the chromosome band 12q13. No rearrangement or amplification could be detected.

The gene for the human putative apoE receptor is on chromosome 12 in the segment q13-14

We have previously described the cDNA coding for a new lipoprotein receptor that contains domains closely related to the ligand-binding domain of the LDL receptor. We have now investigated the localization of the gene for this new receptor by hybridization of the cDNA to panels of rodent cells containing subsets of human chromosomes and by in situ hybridization of the cDNA to chromosomes. The gene maps to 12q13-14, a known hot spot for chromosomal rearrangements in human neoplasia. Of particular interest is the frequent involvement of the 12q13-14 segment in clonal abnormalities in lipomas and myxoid liposarcomas, and it is possible that LRP may play a role in the pathogenesis of such tumors.

No amplification or rearrangement of INT1, GLI, or COL2A1 in uterine leiomyomas with t(12;14)(q14-15;q23-24)

We have studied three uterine leiomyoma tumors, all previously cytogenetically analyzed and shown to have the clonal abnormality t(12:14)(q14-15;q23-24), with the purpose of detecting amplification or rearrangement of three genes that are localized close to the 12q breakpoint region. The genes studied were the two putative oncogenes INT1 and GLI, and the collagen type II alpha 1 gene, COL2A1. No rearrangement or amplification could be detected for any of the three gene sequences.

Chromosome maps of man and mouse. IV

Current knowledge of man-mouse genetic homology is presented in the form of chromosomal displays, tables and a grid, which show locations of the 322 loci now assigned to chromosomes in both species, as well as 12 DNA segments not yet associated with gene loci. At least 50 conserved autosomal segments with two or more loci have been identified, twelve of which are over 20 cM long in the mouse, as well as five conserved segments on the X chromosome. All human and mouse chromosomes now have conserved regions; human 17 still shows the least evidence of rearrangement, with a single long conserved segment which apparently spans the centromere. The loci include 102 which are known to be associated with human hereditary disease; these are listed separately. Human parental effects which may well be the result of genomic imprinting are reviewed and the location of the factors concerned displayed in relation to mouse chromosomal regions which have been implicated in imprinting phenomena.

In situ hybridization localizes the human putative oncogene GLI to chromosome subbands 12q13.3-14.1

Using in situ hybridization, we have localized the human putative oncogene GLI to chromosome subbands 12q13.3-14.1. The precise genomic site is of interest since the region 12q13-15 has been found to be consistently rearranged in neoplasia-associated chromosome abnormalities in lipomas, myxoid liposarcomas, uterine leiomyomas, and pleomorphic adenomas of the salivary gland.

Three major cytogenetic subgroups can be identified among chromosomally abnormal solitary lipomas

We have investigated cytogenetically a total of 35 solitary lipomas, 10 of which have been reported previously. Of the 25 tumours presented herein for the first time, clonal chromosome aberrations were detected in 17. The remaining eight had normal karyotypes, although two of them had nonclonal aberrations in about one quarter of the cells. Based on the cytogenetic findings in all 35 lipomas, four major subgroups can be distinguished. These are characterized by: (I) hyperdiploid karyotypes including one or more supernumerary ring chromosomes (5 cases); (II) diploid karyotypes with mostly balanced rearrangements involving 12q13-14 (13 cases), including the rearrangement t(3;12) (q27-28;q13-14) in 4 cases; (III) hypodiploid or diploid karyotypes with other aberrations than ring chromosomes or rearrangements of 12q13-14 (8 cases); and (IV) normal karyotypes (9 cases).