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Background: B-cell chronic lymphocytic leukemia (B-CLL) is characterized by highly clinical heterogeneity; the identification of reliable prognostic factors useful in predicting patient outcome and planning therapeutic strategies represent a crucial task. Global DNA hypomethylation affecting repeat sequences, such as long interspersed nuclear elements-1 (LINE-1), Alu and satellite α DNA (SAT-α DNA), has been reported in different cancer types and associated with chromosomal instability. Aim: In order to investigate the role of global DNA methylation in B-CLL we quantified the methylation levels of Alu, LINE-1 and SAT-α repetitive in B-CLL patients and correlated them with the major cytogenetic and molecular features and clinical relevance in predicting therapy-free survival (TFS). Patients and methods: A quantitative bisulfite-PCR Pyrosequencing method was used to evaluate methylation of Alu, LINE-1, and SAT-α in a panel of highly purified (>90%) peripheral mononuclear CD19+ cells from 7 healthy donors and 77 B-CLL untreated well-characterized patients in early stage disease (Binet stage A). Results: Forty-eight patients had unmutated IgVH genes; ZAP-70 and CD38 were positive in 28 and 35 cases, respectively; 13q14.3 deletion was present as a sole abnormality in 21/33 patients while in the remaining cases it was combined with 17p13.1 (4 pts) or 11q22.3 deletions (7 pts) or both (1 pt). The 11q22.3 and 17p13.1 deletions were detected as sole abnormality in 6 and 7 patients, respectively. Trisomy 12 occurred in 17 patients, as a sole abnormality in all cases. Methylation levels (median %5mC) were lower in B-CLLs compared with controls (21.4 vs. 25.9; 66.8 vs. 85.7; and 84.0, vs. 88.2; for Alu, LINE-1 and SAT-α, respectively). A significant association was observed with 17p13.1 deletion (15.4 vs. 22.4; 42.9 vs. 68.5; 32.7 vs. 85.0, for Alu, LINE-1 and SAT-α) but not with other major genetic lesions, IgVH mutation status, CD38 or ZAP-70 expression. Notably, lower SAT-α methylation levels appeared to be an independent prognostic marker significantly associated with a shorter TFS. Conclusion: Our study extended limited evidence in methylation of repetitive sequences in B-CLL suggesting an important biological and clinical relevance in the disease. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 181.

BACKGROUND: Inhalation of Particulate Matter (PM) and PM metal components has been associated with increased risk of lung cancer. MicroRNAs (miRNAs) are small, non-coding RNAs with an important role in biological activities and are linked to human diseases such as cancer. miRNA expression needs tight regulation, which also takes place at the epigenetic level. miRNAs undergo regulation by DNA methylation in miRNA coding genes, associate with silencing of miRNA expression. Increased expression of miR-21 has been implicated in various processes involved in carcinogenesis, including inhibition of apoptosis, promotion of cell proliferation and stimulation of tumor growth by targeting multiple tumor/metastasis suppressor genes. In cancer cells miR-222 promotes cell proliferation by targetting the cell cycle inhibitor and tumor suppressor p27. AIMS: We evaluated the effects of exposure to PM and PM metal components on candidate miRNAs methylation (miR-222 and miR-21) in 63 workers of an electric-furnace steel plant with well-characterized exposure. METHODS: We measured miR-222 and miR-21 methylation in blood leukocyte RNA obtained from 63 workers on the first day of a workweek (baseline) and after three days of work (post-exposure). Quantitative miRNA methylation analysis was performed through bisulfite PCR Pyrosequencing. We estimated individual exposures to PM1, PM10, coarse particles and PM metal components (chromium, lead, cadmium, arsenic, nickel, manganese) between the baseline and post-exposure measurements. RESULTS: miR-222 and miR-21 methylation was significantly decreased in post-exposure samples, compared with baseline (post-exposure=60.07±9.38, baseline=63.05±6.38; p=0.013 for miR-222; post-exposure=62.47±6.87, baseline=66.24±6.32; p=0.004 for miR-21). In post-exposure samples, miR-222 methylation was negatively associated with the average exposure to the levels of PM (βstd=-0.012, p=0.03 for PM10, βstd=-0.579, p=0.005 for PM1 and βstd=-0.013, p=0.032 for Coarse) and to the levels of PM metal components (βstd=-111.345, p=0.008 for Chromium and βstd=17.195, p=0.023 for Arsenic). CONCLUSIONS: Changes in miRNA methylation may represent a novel epigenetic mechanism mediating responses to PM and its metal components. Whether these modifications have a role in the initiation and progression of cancer needs to be evaluated in future studies. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4088.

BACKGROUND: In utero exposure to xenostrogens may modify the epigenome. We explored the association of prenatal exposure to mixtures of xenoestrogens and genome-wide placental DNA methylation. MATERIALS & METHODS: Sex-specific associations between methylation changes in placental DNA by doubling the concentration of TEXB-alpha exposure were evaluated by robust multiple linear regression. Two CpG sites were selected for validation and replication in additional male born placentas. RESULTS: No significant associations were found, although the top significant CpGs in boys were located in the LRPAP1, HAGH, PPARGC1B, KCNQ1 and KCNQ1DN genes, previously associated to birth weight, Type 2 diabetes, obesity or steroid hormone signaling. Neither technical validation nor biological replication of the results was found in boys for LRPAP and PPARGC1B. CONCLUSION: Some suggestive genes were differentially methylated in boys in relation to prenatal xenoestrogen exposure, but our initial findings could not be validated or replicated. This work was part of the European-wide project Transportation Air pollution and Physical ActivitieS (TAPAS): an integrated health risk assessment program of climate change and urban policies, which had partners in Barcelona, Basel, Copenhagen, Paris, Prague, and Warsaw. TAPAS was a 4-year project funded by the Coca-Cola Foundation, AGAUR, and CREAL (http://www.tapas-program.org/). CREAL is part of CIBERESP (http://www.ciberesp.es/), the Spanish Network for Epidemiology and Public Health Research. CREAL and its members are based at and supported by the Universitat Pompeu Fabra (http://www.upf.edu/en/).