Amplified region of chromosome band 11q13 in breast and squamous cell carcinomas encompasses three CpG islands telomeric of FGF3, including the expressed gene EMS1

DNA markers that map within the karyotypically defined band q13 on human chromosome 11 are amplified in a subset of mammary and squamous cell carcinomas. It is assumed that the amplified DNA includes a critical gene (or genes) whose overexpression provides a selective force in the development of the tumor. To help identify such genes, we have begun to construct a physical map of CpG islands in the region, making use of a squamous cell carcinoma cell line (UMSCC2) in which the 11q13 region is amplified 11-fold. We previously described the proximal end of this amplicon and the order of markers extending ～800 kb centromeric of the FGF3 locus (formerly INT2). We now report the use of chromosome jumping techniques to define additional CpG islands that lie distal to FGF3. These map within the amplified region in UMSCC2 cells and the most telomeric corresponds to the EMS1 gene. The data imply that the amplified DNA in UMSCC2 cells extends for over 1,500 kb and includes at least 7 potential genes. EMS1 and CCND1 (formerly PRAD1), the best candidates for the key gene on the 11q13 amplicon, are ≥800 kb apart. © 1993 Wiley-Liss, Inc.     

Expression of antigen reactive with a monoclonal antibody to HTLV-1 P19 in salivary glands in Sjögren''s syndrome.

To examine the possible involvement of retroviruses in Sjögren's syndrome (SS), labial salivary gland sections from 99 individuals were probed with three MoAbs to core (gag) proteins of human T cell leukaemia virus-1 (HTLV-1) and two MoAbs to HIV-1. Sections from 31% of 39 patients with primary SS (pSS) contained an epithelial cytoplasmic protein reactive with a MoAb(197) to the p19 group specific antigen (gag) of HTLV-1. The antigen was also detected in samples from 24% of 17 patients with rheumatoid arthritis (RA) and SS. 21% of 14 patients with sicca symptoms and 12.5% of 16 patients with other connective tissue diseases. It was not found in the salivary glands of 13 normal controls. A second MoAb to p19 gag, a MoAb to the p24 gag of HTLV-1 and MoAbs to HIV-1 p17and p24 gags gave negative reactions. Serum antibodies to HTLV-1 were negative, confirming that the antigen was not part of HTLV-1. The antigen showed properties consistent with an endogenous retrovirus in that it was absent in healthy tissues or resting cells but inducible by stimulation with phytohaemagglutinin (PHA) or interferon-gamma (IFN-γ) It appeared to be distinct from the endogenous retroviral sequence HRES-1. These data suggest the presence of an endogenous retrovirus in salivary gland epithelium which could contribute to the chronic inflammation of SS.     

Detection of reactive oxygen species (ROS) and apoptosis in human fragmented embryos

In human in-vitro fertilization (IVF)-embryo transfer, the in-vitro culture environment differs from in-vivo conditions in that the oxygen concentration is higher, and in such conditions the mouse embryos show a higher concentration of reactive oxygen species (ROS) in simple culture media. ROS are believed to cause damage to cell membranes and DNA fragmentation in somatic cells. This study was conducted to ascertain the level of H2O2 concentration within embryos and the morphological features of cell damage induced by H2O2. A total of 62 human oocytes and embryos (31 fragmented, 15 non-fragmented embryos, 16 unfertilized oocytes) was obtained from the IVF-embryo transfer programme. The relative intensity of H2O2 concentrations within embryos was measured using 2',7'-dichlorodihydrofluorescein diacetate by Quanti cell 500 fluorescence imaging and DNA fragmentation was observed with transmission electron microscopy and an in-situ apoptosis detection kit. The H2O2 concentrations were significantly higher in fragmented embryos (72.21 +/- 9.62, mean +/- SEM) compared to non-fragmented embryos (31.30 +/- 3.50, P < 0.05) and unfertilized oocytes (30.75 +/- 2.67, P < 0.05). Apoptosis was observed only in fragmented embryos, and was absent in non-fragmented embryos. Electron microscopic findings confirmed apoptotic bodies and cytoplasmic condensation in the fragmented blastomeres. We conclude that there is a direct relationship between increased H2O2 concentration and apoptosis, and that further studies should be undertaken to confirm these findings.      

Germline mutations of the CDKN2 gene in UK melanoma families

Germline mutations in CDKN2 on chromosome 9p21, which codes for the cyclin D kinase inhibitor p16, and more rarely, mutations in the gene coding for CDK4, the protein to which p16 binds, underlie susceptibility in some melanoma families. We have sequenced all exons of CDKN2 and analysed the CDK4 gene for mutations in 27 UK families showing evidence of predisposition to melanoma. Five different germline mutations in CDKN2 were found in six families. Three of the mutations (Met53Ile, Arg24Pro and 23ins24) have been reported previously. We have identified two novel CDKN2 mutations (88delG and Ala118Thr) which are likely to be associated with the development of melanoma, because of their co-segregation with the disease and their likely functional effect on the CDKN2 protein. In binding assays the protein expressed from the previously described mutation, Met53Ile, did not bind to CDK4/CDK6, confirming its role as a causal mutation in the development of melanoma. Ala118Thr appeared to be functional in this assay. Arg24Pro appeared to bind to CDK6, but not to CDK4. No mutations were detected in exon 2 of CDK4, suggesting that causal mutations in this gene are uncommon. The penetrance of these mutant CDKN2 genes is not yet established, nor is the risk of non-melanoma cancer to gene carriers.      

Elevated amyloid beta protein (Abeta42) and late onset Alzheimer's disease are associated with single nucleotide polymorphisms in the urokinase-type plasminogen activator gene

Plasma amyloid beta protein (Abeta42) levels and late onset Alzheimer's disease (LOAD) have been linked to the same region on chromosome 10q. The PLAU gene within this region encodes urokinase-type plasminogen activator, which converts plasminogen to plasmin. Abeta aggregates induce PLAU expression thereby increasing plasmin, which degrades both aggregated and non-aggregated forms of Abeta. We evaluated single nucleotide polymorphisms (SNPs) in PLAU for association with Abeta42 and LOAD. PLAU SNP compound genotypes composed of haplotype pairs showed significant association with AD in three independent case-control series. PLAU SNP haplotypes associated significantly with plasma Abeta42 in 10 extended LOAD families. One of the SNPs analyzed was a missense C/T polymorphism in exon 6 of PLAU (PLAU_1=rs2227564), which causes a proline to leucine change (P141L). We analyzed PLAU_1 for association with AD in six case-control series and 24 extended LOAD families. The CT and TT PLAU_1 genotypes showed association (P=0.05) with an overall estimated odds ratio of 1.2 (1.0-1.5). The CT and TT genotypes of PLAU_1 were also associated with significant age-dependent elevation of plasma Abeta42 in 24 extended LOAD families (P=0.0006). In knockout mice lacking the PLAU gene, plasma--but not brain--Abeta42 as well as Abeta40 was significantly elevated, also in an age-dependent manner. The PLAU_1 associations were independent of the associations we found among plasma Abeta42, LOAD and variants in the IDE or VR22 region. These results provide strong evidence that PLAU or a nearby gene is involved in the development of LOAD. PLAU_1 is a plausible pathogenic mutation that could act by increasing Abeta42, but additional biological experiments are required to show this definitively.     

Mechanisms of cell signaling by nitric oxide and peroxynitrite: from mitochondria to MAP kinases

Many of the biological and pathological effects of nitric oxide (NO) are mediated through cell signaling pathways that are initiated by NO reacting with metalloproteins. More recently, it has been recognized that the reaction of NO with free radicals such as superoxide and the lipid peroxyl radical also has the potential to modulate redox signaling. Although it is clear that NO can exert both cytotoxic and cytoprotective actions, the focus of this overview are those reactions that could lead to protection of the cell against oxidative stress in the vasculature. This will include the induction of antioxidant defenses such as glutathione, activation of mitogen-activated protein kinases in response to blood flow, and modulation of mitochondrial function and its impact on apoptosis. Models are presented that show the increased synthesis of glutathione in response to shear stress and inhibition of cytochrome c release from mitochondria. It appears that in the vasculature NO-dependent signaling pathways are of three types: (i) those involving NO itself, leading to modulation of mitochondrial respiration and soluble guanylate cyclase; (ii) those that involve S-nitrosation, including inhibition of caspases; and (iii) autocrine signaling that involves the intracellular formation of peroxynitrite and the activation of the mitogen-activated protein kinases. Taken together, NO plays a major role in the modulation of redox cell signaling through a number of distinct pathways in a cellular setting.     

Genetic variation in a haplotype block spanning IDE influences Alzheimer disease

Linkage studies have identified a large (>60-Mb) region on chromosome 10q that segregates with Alzheimer Disease (AD). Within the region, the gene for insulin degrading enzyme (IDE) represents a notable biological candidate given that it degrades amyloid beta-protein (one of the major constituents of senile plaques) and the intracellular amyloid precursor protein (APP) domain released by gamma-secretase processing. We have used a single nucleotide polymorphism (SNP) genetic association strategy to investigate AD in relation to a 480-kb region encompassing IDE. A 276-kb linkage disequilibrium block was revealed that spans three genes (IDE, KNSL1, and HHEX). Assessing this block in several independent sets of case-control materials (early- and late-onset AD) and focusing also upon quantitative measures that are pertinent to AD diagnosis and severity (MMSE scores, microtubule-associated protein Tau [MAPT] levels in CSF, degree of brain pathology, and age-at-onset) produced extensive evidence for significant AD association. Signals (p-values ranging from 0.05 to <1x10(-9)) were generally stronger when examining haplotypes rather than individual SNPs, and quantitative trait tests most uniformly revealed the detected associations. Consistent risk alleles and haplotypes were apparent across the study, with effects in some cases as large as that of the epsilon4 allele of APOE. A subsequent mutation screen of exons in all three suspect genes provided no evidence for common causative mutations. These results provide substantial evidence that genetic variation within or extremely close to IDE impacts both disease risk and traits related to the severity of AD.     

Linkage map of a region of human chromosome band 11q13 amplified in breast and squamous cell tumors.

DNA amplification involving markers on human chromosome band 11q13 is a consistent feature of several major cancers, notably adenocarcinoma of the breast and squamous cell carcinoma of the head, neck, lung, and esophagus. Since the presence of the amplification may be clinically significant, by defining a subset of patients at increased risk, it is important to establish which of the several genes on the amplified DNA provides the selective force. Here we describe a physical map of the centromeric end of the amplified DNA as it exists in a particular squamous carcinoma cell line (UMSCC2) and establish an unambiguous order for several known markers in the region, including pMS51/D11S97, pHB159/D11S146, BCL1, PRAD1/D11S287, HSTF1/FGF4 and INT2/FGF3. Significantly, PRAD1 is within 120-150 kb of the BCL1 translocation breakpoint and the data identify a new CpG island (D11S814) between PRAD1 and HSTF1. The ordering of the HSTF1 and INT2 genes and the clustering of CpG islands in the region have important implications in assessing whether the frequently observed amplifications at 11q13 are centered on one or more genes.     

Chromosome 11q13 markers and D-type cyclins in breast cancer

Summary One in six primary human breast cancers has DNA amplification centered on the cyclin D1 gene (CCND1) on chromosome 11q13. This genetic abnormality is preferentially associated with estrogen-receptor positive tumors and may define a sub-class of patients with an adverse prognosis. AlthoughCCND1 has the credentials of a cellular oncogene, being a target for chromosomal translocation and retroviral integration, the 11q13 amplicon encompasses several other markers andCCND1 is not the only candidate for the key gene on the amplified DNA. To assess their relative importance, we have constructed a physical map of the amplified DNA and compared the extent and frequency of amplification across the region. Since it is likely that the gene providing the selective force for amplification will be expressed at elevated levels, we have also examined expression of both RNA and protein. By these criteria, cyclin D1 remains the strongest candidate for the key oncogene on the amplicon and we are currently investigating the functional consequences of its over-expression.Presented by Gordon Peters at the 16th Annual San Antonio Breast Cancer Symposium, San Antonio TX, USA, November 4, 1993; Minisymposium on Molecular Genetics in Breast Cancer.