ALBERT

Description: Gene silencing mediated by aberrant promoter DNA hypermethylation represents a key mechanism by which tumor suppressor gene expression is silenced in cancer and it is associated with multiple repressive histone modifications. Histone H3 lysine 9 (H3K9) methylation is a key repressive chromatin modification with important implications for regulating cell proliferation, differentiation, and gene expression. SUV39H1 is a methyltransferase that catalyzes the addition of trimethyl groups to H3K9. SUV39H1 is associated with regions of hypermethylated CpG islands, with repressive complexes, such as RB/E2F, and with DNA-binding proteins involved in leukemogenesis, such as AML1 and PML-RAR, where its H3K9 trimethylation activity promotes heterochromatin formation and gene silencing. We studied the requirement of SUV39H1 in the epigenetic silencing of heavily methylated tumor suppressor genes p15INK4B and E-cadherin in acute myeloid leukemia (AML). Treatment of AML cell lines AML193, KG1a, and Kasumi with the DNA methyltransferase (DNMT) inhibitor 5-Aza-2’-deoxycytidine (5-Aza-dC) induces p15INK4B and E-cadeherin re-expression in association with dramatic decreases in p15INK4B and E-cadherin promoter DNA methylation and marked reductions in the levels of SUV39H1 and H3K9 trimethylation at these promoters. Interestingly, treatment of these cell lines with SUV39H1 shRNA, or the SUV39H1 inhibitor chaetocin, also induces p15INK4B and E-cadherin re-expression and H3K9 demethylation, without affecting promoter DNA methylation. Thus, re-expression of hypermethylated tumor suppressors requires histone H3K9 demethylation, which can be achieved indirectly by decreasing the amount of SUV39H1 associated with the promoter using 5-Aza-dC, or directly by inhibiting SUV39H1 expression or activity without requiring promoter DNA demethylation. Furthermore, we found that SUV39H1 shRNA or chaetocin in combination with 5-Aza-dC acts synergistically to re-express epigenetically silenced p15INK4B and E-cadherin in AML cell lines. Treatment of primary human AML blasts obtained from two patients with combinations of 5-Aza-C and chaetocin also results in synergistic re-expression of p15INK4B and E-cadherin (2–6 fold increase with 5-Aza-C or chaetocin treatment vs. 11–14 fold increase with co-treatment). Our study has important implications for developing novel epigenetic therapies of relevance to AML as it suggests that the re-expression of tumor suppressor genes silenced by aberrant promoter DNA hypermethylation converges on the requirement for SUV39H1 and H3K9 methylation inhibition but not promoter DNA demethylation. Our finding that SUV39H1 inhibition may function synergistically with DNMT inhibitors to enhance gene reactivation and chromatin changes also highlights the needs for developing more inhibitors of histone methyltransferases and for performing detailed drug interaction studies to identify the best drug combinations for optimal epigenetic therapies.

Description: To evaluate the hypothesis that host germ line variation in immune genes is associated with overall survival in diffuse large B-cell lymphoma (DLBCL), we genotyped 73 single nucleotide polymorphisms (SNPs) from 44 candidate genes in 365 DLBCL patients diagnosed from 1998 to 2000. We estimated hazard ratios (HRs) and 95% confidence intervals (CIs) for the association of SNPs with survival after adjusting for clinical factors. During follow-up, 96 (26%) patients died, and the median follow-up was 57 months for surviving patients. The observed survival of this cohort was consistent with population-based estimates conditioned on surviving 12 months. An IL10 haplotype (global P = .03) and SNPs in IL8RB (rs1126580; HRAG/GG = 2.11; CI, 1.28-3.50), IL1A (rs1800587; HRCT/TT = 1.90; CI, 1.26-2.87), TNF (rs1800629; HRAG/GG = 1.44; CI, 0.95-2.18), and IL4R (rs2107356; HRCC/CT = 1.97; CI, 1.01-3.83) were the strongest predictors of overall survival. A risk score that combined the latter 4 SNPs with clinical factors was strongly associated with survival in a Cox model (P = 6.0 × 10−11). Kaplan-Meier 5-year survival estimates for low, intermediate-low, intermediate-high, and high-risk patients were 94%, 79%, 60%, and 48%, respectively. These data support a role for germ line variation in immune genes, particularly genes associated with a proinflammatory state, as predictors of late survival in DLBCL.

Description: The Cambrian inlier at Beaver Harbour, southern New Brunswick, is now confidently referred to the marginal platform of the late Proterozoic–Early Paleozoic Avalon microcontinent. The sub-trilobitic Lower Cambrian Chapel Island and Random Formations are unconformably overlain by the mafic volcanic-dominated Wade's Lane Formation (new). Late Early Cambrian trilobites and small shelly taxa in the lowest Wade's Lane demonstrate a long Random–Wade's Lane hiatus (middle Terreneuvian–early Branchian). Latest Early–middle Middle Cambrian pyroclastic volcanism produced a volcanic edifice at Beaver Harbour that is one of three known volcanic centers that extended 550 km along the northwest margin of Avalon. Middle Middle Cambrian sea-level rise, probably in the Paradoxides eteminicus Chron, mantled the extinct volcanics with gray-green mudstone and limestone of the Fossil Brook Member. Black, dysoxic mudstone of the upper Manuels River Formation (upper Middle Cambrian, P. davidis Zone) is the youngest Cambrian unit in the Beaver Harbour inlier. Lapworthella cornu (Wiman, 1903) emend., a senior synonym of the genotype L. nigra (Cobbold, 1921), Hyolithellus sinuosus Cobbold, 1921, and probably Acrothyra sera Matthew, 1902a, range through the ca. 8 m.y. of the trilobite-bearing upper Lower Cambrian, and H. sinuosus and A. sera persist into the middle Middle Cambrian. Lapworthella cornu and H. sinuosus replaced the tropical taxa L. schodackensis (Lochman, 1956) and H. micans Billings, 1872, in cool-water Avalon.