| 1. |
- Kaaks, Rudolf, et al.
(författare)
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Insulin-like Growth Factor-II Methylation Status in Lymphocyte DNA and Colon Cancer Risk in the Northern Sweden Health and Disease Cohort
- 2009
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Ingår i: Cancer Research. - 0008-5472 .- 1538-7445. ; 69:13, s. 5400-5405
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Tidskriftsartikel (refereegranskat)abstract
- Loss of imprinting (LOI) of the insulin-like growth factor II (IGFII) gene is a frequent phenomenon in colorectal tumor tissues. Previous reports indicated that subjects with colorectal neoplasias show LOI of IGFII in circulating lymphocytes. Furthermore, LOI of IGFII is strongly related to the methylation of a differentially methylated region (DMR) in intron 2 of IGFII, suggesting that the methylation status could serve as a biomarker for early detection. Thus, hypermethylation of this DMR, even at a systemic level, e.g., in lymphocyte DNA, could be used for screening for colon cancer. To validate this, we performed a case-control study of 97 colon cancer cases and 190 age-matched and gender-matched controls, nested within the prospective Northern Sweden Health and Disease Study cohort. Methylation levels of the IGFII-DMR in lymphocyte DNA were measured at two specific CpG sites of the IGFII-DMR using a mass-spectrometric method called short oligonucleotide mass analysis, the measurements of which showed high reproducibility between replicate measurements for the two CpG sites combined and showed almost perfect validity when performed on variable mixtures of methylated and unmethylated standards. Mean fractions of CpG methylation, for the two CpG sites combined, were identical for cases and controls (0.47 and 0.46, respectively; Pdifference = 0.75), and logistic regression analyses showed no relationship between colon cancer risk and quartile levels of CpG methylation. The results from this study population do not support the hypothesis that colon cancer can be predicted from the different degrees of methylation of DMR in the IGFII gene from lymphocyte DNA. [Cancer Res 2009;69(13):5400-5].
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| 2. |
- Raval, Aparna, et al.
(författare)
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Downregulation of death-associated protein kinase 1 (DAPK1) in chronic lymphocytic leukemia
- 2007
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Ingår i: Cell. - : Elsevier BV. - 0092-8674 .- 1097-4172. ; 129:5, s. 879-890
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Tidskriftsartikel (refereegranskat)abstract
- The heritability of B cell chronic lymphocytic leukemia (CLL) is relatively high; however, no predisposing mutation has been convincingly identified. We show that loss or reduced expression of death-associated protein kinase 1 (DAPK1) underlies cases of heritable predisposition to CLL and the majority of sporadic CLL. Epigenetic silencing of DAPK1 by promoter methylation occurs in almost all sporadic CLL cases. Furthermore, we defined a disease haplotype, which segregates with the CLL phenotype in a large family. DAPK1 expression of the CLL allele is downregulated by 75% in germline cells due to increased HOXB7 binding. In the blood cells from affected family members, promoter methylation results in additional loss of DAPK1 expression. Thus, reduced expression of DAPK1 can result from germline predisposition, as well as epigenetic or somatic events causing or contributing to the CLL phenotype.
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