A mutation in POLE predisposing to a multi-tumour phenotype

Somatic mutations in the POLE gene encoding the catalytic subunit of DNA polymerase epsilon have been found in sporadic colorectal cancers (CRCs) and are most likely of importance in tumour development and/or progression. Recently, families with dominantly inherited colorectal adenomas and colorectal cancer were shown to have a causative heterozygous germline mutation in the proofreading exonuclease domain of POLE. The highly penetrant mutation was associated with predisposition to CRC only and no extra-colonic tumours were observed. We have identified a mutation in a large family in which the carriers not only developed CRC, they also demonstrate a highly penetrant predisposition to extra-intestinal tumours such as ovarian, endometrial and brain tumours. The mutation, NM_006231.2:c.1089C>A, p.Asn363Lys, also located in the proofreading exonuclease domain is directly involved in DNA binding. Theoretical prediction of the amino acid substitution suggests a profound effect of the substrate binding capability and a more severe impairment of the catalytic activity compared to the previously reported germline mutation. A possible genotype to phenotype correlation for deleterious mutations in POLE might exist that needs to be considered in the follow-up of mutation carriers

Expanding the genotype-phenotype spectrum in hereditary colorectal cancer by gene panel testing

Hereditary syndromes causing colorectal cancer include both polyposis and non-polyposis syndromes. Overlapping phenotypes between the syndromes have been recognized and this make targeted molecular testing for single genes less favorable, instead there is a gaining interest for multi-gene panel-based approaches detecting both SNVs, indels and CNVs in the same assay. We applied a panel including 19 CRC susceptibility genes to 91 individuals of six phenotypic subgroups. Targeted NGS-based sequencing of the whole gene regions including introns of the 19 genes was used. The individuals had a family history of CRC or had a phenotype consistent with a known CRC syndrome. The purpose of the study was to demonstrate the diagnostic difficulties linked to genotype-phenotype diversity and the benefits of using a gene panel. Pathogenicity classification was carried out on 46 detected variants. In total we detected sixteen pathogenic or likely pathogenic variants and 30 variants of unknown clinical significance. Four of the pathogenic or likely pathogenic variants were found in BMPR1A in patients with unexplained familial adenomatous polyposis or atypical adenomatous polyposis, which extends the genotype-phenotype spectrum for this gene. Nine patients had more than one variant remaining after the filtration, including three with truncating mutations in BMPR1A, PMS2 and AXIN2. CNVs were found in three patients, in upstream regions of SMAD4, MSH3 and CTNNB1, and one additional individual harbored a 24.2 kb duplication in CDH1 intron1

Lipoprotein(a) in cardiovascular disease

The atherosclerotic process is continuous and starts early in life. Risk factors for atherosclerosis include hyperlipidemia, hypertension, smoking and diabetes mellitus. Fatty streaks characterised by lipid-laden macrophages are early signs of atherosclerosis. Binding of LowDensityLipoproteins(LDL) to proteoglycans is believed to be one of the first steps in atherosclerosis. After many years the plaques are more complex with aggregations of lipids, extracellular matrix, and necrotic cells with variable content of inflammatory cells. The etiology of atherosclerosis is complex and multifactorial. Several new risk factors have been studied recently. On such factor may be lipoprotein(a)(Lp(a)). Lp(a) has been associated to cardiovascular disease in several studies. Lp(a) is an LDL-like particle with an apolipoprotein(a) part attached to apoB by a disulfide bridge.The regulation of serum levels of Lp(a) has been studied in this thesis. It has earlier been shown that Growth Hormone increases the levels of Lp(a). It has been speculated that this effect could be mediated by Insulin-like Growth Factor-1(IGF-1). Effects of IGF-1 treatment were tested in the present study during a two weeks period. The results demonstrate that IGF-1 treatment resulted in decreased levels of Lp(a)(-18.5%). Lowered levels of cholesterol and triglycerides were also seen. We also studied the effects of N-acetylcysteine treatment. No effect of N-acetylcysteine treatment on Lp(a) was seen during treatment. There was a reduction of homocysteine, cysteinylglycine and glycine as a response to the treatment. The interactions of Lp(a) and LDL with extracellular matrix have been investigated. In studies with human arterial smooth muscle cell derived extracellular matrix we saw an increased binding of 125I-LDL in the presence of Lp(a). This binding was reduced after treatment of the matrix with chondroitinase ABC, implying an involvement of proteoglycans in the interaction. In addition the interaction of 125I-LDL with matrix was stronger in the presence of Lp(a). In a population with coronary heart disease (n=964) Lp(a)levels and apo(a) isoforms was studied as a prognostic factor during a twelve years follow-up.A total of 363 patients died during follow-up. The smallest isoform of apo(a) was associated with a two-fold increase in risk. High levels of lipoprotein(a) were not associated with increased risk. In women, but not in men the risk decreased with increasing molecular weight of the apo(a) isoforms. These results support the endocrine regulation of serum Lp(a) levels, specifically a reduction by IGF-1 was seen. Lp(a) increases the binding of LDL to human arterial smooth muscle cell derived extracellular matrix in vitro. More LDL particles are bound in the presence of Lp(a) and the interaction is stronger. Apo(a) isoforms but not Lp(a) levels were found to be risk factors in patients with CHD, especially among women. These findings emphasize the importance of a gender-specific analysis of risk factors for CHD

Increasing peripheral artery intima thickness from childhood to seniority

Background - Using new, very high-resolution ultrasound biomicroscopy, we examined the thickness of artificial layers of silicone and intima thickness (IT) of radial and anterior tibial arteries in healthy subjects and in patients with vascular disease. Methods and Results - Silicone layers of varying thicknesses and mesenteric artery specimens obtained from 18 patients undergoing colectomy were measured by both ultrasound biomicroscopy (55 MHz) and morphometry. There was high correlation (r > 0.9; P < 0.0001) between IT and intima area versus ultrasound biomicroscopy. In 90 healthy subjects (aged between 10 and 90 years), radial and anterior tibial arterial IT and intima-media thickness were measured, as was carotid intima-media thickness in 56 of these subjects. Age was strongly related with both media thickness and IT of both peripheral arteries. Correlations were found between carotid intima-media thickness and both radial and anterior tibial IT/intima-media thickness (r=0.44 to 0.53; P < 0.0001). The IT-to-lumen diameter ratio increased with age and was larger at all ages in the anterior tibial artery (0.067 +/- 0.034) versus the radial artery (0.036 +/- 0.012; P < 0.0001). A thicker radial intimal layer was found in patients with peripheral artery disease. Conclusion - This study is the first to our knowledge in humans to show the feasibility of measuring IT of the radial and anterior tibial arteries using very high-resolution ultrasound. IT progresses with age, and the IT-to-lumen diameter ratio is largest in the arteries of the foot. Assessment of IT by ultrasound biomicroscopy may aid in detecting early peripheral vascular abnormalities

GREM1 and POLE variants in hereditary colorectal cancer syndromes

Hereditary factors are thought to play a role in at least one third of patients with colorectal cancer (CRC) but only a limited proportion of these have mutations in known high-penetrant genes. In a relatively large part of patients with a few or multiple colorectal polyps the underlying genetic cause of the disease is still unknown. Using exome sequencing in combination with linkage analyses together with detection of copy-number variations (CNV), we have identified a duplication in the regulatory region of the GREM1 gene in a family with an attenuated/atypical polyposis syndrome. In addition, 107 patients with colorectal cancer and/or polyposis were analyzed for mutations in the candidate genes identified. We also performed screening of the exonuclease domain of the POLE gene in a subset of these patients. The duplication of 16 kb in the regulatory region of GREM1 was found to be disease-causing in the family. Functional analyses revealed a higher expression of the GREM1 gene in colorectal tissue in duplication carriers. Screening of the exonuclease domain of POLE in additional CRC patients identified a probable causative novel variant c.1274A>G, p.Lys425Arg. In conclusion a high penetrant duplication in the regulatory region of GREM1, predisposing to CRC, was identified in a family with attenuated/atypical polyposis. A POLE variant was identified in a patient with early onset CRC and a microsatellite stable (MSS) tumor. Mutations leading to increased expression of genes can constitute disease-causing mutations in hereditary CRC syndromes. \ua9 2015 The Authors. Genes, Chromosomes & Cancer Published by Wiley Periodicals, Inc

GREM1 and POLE variants in hereditary colorectal cancer syndromes

Hereditary factors are thought to play a role in at least one third of patients with colorectal cancer (CRC) but only a limited proportion of these have mutations in known high-penetrant genes. In a relatively large part of patients with a few or multiple colorectal polyps the underlying genetic cause of the disease is still unknown. Using exome sequencing in combination with linkage analyses together with detection of copy-number variations (CNV), we have identified a duplication in the regulatory region of the GREM1 gene in a family with an attenuated/atypical polyposis syndrome. In addition, 107 patients with colorectal cancer and/or polyposis were analyzed for mutations in the candidate genes identified. We also performed screening of the exonuclease domain of the POLE gene in a subset of these patients. The duplication of 16 kb in the regulatory region of GREM1 was found to be disease-causing in the family. Functional analyses revealed a higher expression of the GREM1 gene in colorectal tissue in duplication carriers. Screening of the exonuclease domain of POLE in additional CRC patients identified a probable causative novel variant c.1274A>G, p.Lys425Arg. In conclusion a high penetrant duplication in the regulatory region of GREM1, predisposing to CRC, was identified in a family with attenuated/atypical polyposis. A POLE variant was identified in a patient with early onset CRC and a microsatellite stable (MSS) tumor. Mutations leading to increased expression of genes can constitute disease-causing mutations in hereditary CRC syndromes. \ua9 2015 The Authors. Genes, Chromosomes & Cancer Published by Wiley Periodicals, Inc

Orellanine specifically targets renal clear cell carcinoma

Renal cell carcinoma (RCC), arising from the proximal tubule in the kidney, accounts for approximately 85% of kidney cancers and causes over 140,000 annual deaths worldwide. In the last decade, several new therapies have been identified for treatment of metastatic RCC. Although these therapies increase survival time compared to standard care, none of them has curative properties. The nephrotoxin orellanine specifically targets proximal tubular epithelial cells, leaving other organs unaffected. We therefore hypothesized that the selective toxicity of orellanine extends to clear cell RCC (ccRCC) cells since they emanate from proximal tubular cells. Orellanine would thus target both primary and metastatic ccRCC in vitro and in vivo. We found that orellanine induces dose-dependent cell death in proximal tubular cells and in all ccRCC cells tested, both primary and cell lines, with no toxicity detected in control cells. The toxic action of orellanine involve decreased protein synthesis, disrupted cell metabolism and induction of apoptosis. In nude rats carrying human ccRCC xenografts, brief orellanine treatment eliminated more than 90% of viable tumor mass compared to control rats. This identifies orellanine as a potential treatment concept for ccRCC patients on dialysis, due to its unique selective toxicity towards ccRCC