Somatic mutations in the transcriptional corepressor gene BCORL1 in adult acute myelogenous leukemia.

To further our understanding of the genetic basis of acute myelogenous leukemia (AML), we determined the coding exon sequences of ∼ 18 000 protein-encoding genes in 8 patients with secondary AML. Here we report the discovery of novel somatic mutations in the transcriptional corepressor gene BCORL1 that is located on the X-chromosome. Analysis of BCORL1 in an unselected cohort of 173 AML patients identified a total of 10 mutated cases (6%) with BCORL1 mutations, whereas analysis of 19 AML cell lines uncovered 4 (21%) BCORL1 mutated cell lines. The majority (87%) of the mutations in BCORL1 were predicted to inactivate the gene product as a result of nonsense mutations, splice site mutation, or out-of-frame insertions or deletions. These results indicate that BCORL1 by genetic criteria is a novel candidate tumor suppressor gene, joining the growing list of genes recurrently mutated in AML.

The prognostic significance of various 13q14 deletions in chronic lymphocytic leukemia.

PURPOSE: To further our understanding of the biology and prognostic significance of various chromosomal 13q14 deletions in chronic lymphocytic leukemia (CLL). EXPERIMENTAL DESIGN: We analyzed data from SNP 6.0 arrays to define the anatomy of various 13q14 deletions in a cohort of 255 CLL patients and have correlated two subsets of 13q14 deletions (type I exclusive of RB1 and type II inclusive of RB1) with patient survival. Furthermore, we measured the expression of the 13q14-resident microRNAs by quantitative PCR (Q-PCR) in 242 CLL patients and subsequently assessed their prognostic significance. We sequenced all coding exons of RB1 in patients with monoallelic RB1 deletion and have sequenced the 13q14-resident miR locus in all patients. RESULTS: Large 13q14 (type II) deletions were detected in approximately 20% of all CLL patients and were associated with shortened survival. A strong association between 13q14 type II deletions and elevated genomic complexity, as measured through CLL-FISH or SNP 6.0 array profiling, was identified, suggesting that these lesions may contribute to CLL disease evolution through genomic destabilization. Sequence and copy number analysis of the RB1 gene identified a small CLL subset that is RB1 null. Finally, neither the expression levels of the 13q14-resident microRNAs nor the degree of 13q14 deletion, as measured through SNP 6.0 array-based copy number analysis, had significant prognostic importance. CONCLUSIONS: Our data suggest that the clinical course of CLL is accelerated in patients with large (type II) 13q14 deletions that span the RB1 gene, therefore justifying routine identification of 13q14 subtypes in CLL management.

Acquired genomic copy number aberrations and survival in chronic lymphocytic leukemia.

Genomic aberrations are of predominant importance to the biology and clinical outcome of patients with chronic lymphocytic leukemia (CLL), and FISH-based genomic risk classifications are routinely used in clinical decision making in CLL. One of the known limitations of CLL FISH is the inability to comprehensively interrogate the CLL genome for genomic changes. In an effort at overcoming the existing limitations in CLL genome analysis, we have analyzed high-purity DNA isolated from FACS-sorted CD19(+) cells and paired CD3(+) or buccal cells from 255 patients with CLL for acquired genomic copy number aberrations (aCNAs) with the use of ultra-high-density Affymetrix SNP 6.0 arrays. Overall, ≥ 2 subchromosomal aCNAs were found in 39% (100 of 255) of all cases analyzed, whereas ≥ 3 subchromosomal aCNAs were detected in 20% (50 of 255) of cases. Subsequently, we have correlated genomic lesion loads (genomic complexity) with the clinical outcome measures time to first therapy and overall survival. With the use of multivariate analyses incorporating the most important prognostic factors in CLL together with SNP 6.0 array-based genomic lesion loads at various thresholds, we identify elevated CLL genomic complexity as an independent and powerful marker for the identification of patients with aggressive CLL and short survival.

A pathobiological role of the insulin receptor in chronic lymphocytic leukemia.

PURPOSE: The chromosomal deletion 11q affects biology and clinical outcome in chronic lymphocytic leukemia (CLL) but del11q-deregulated genes remain incompletely characterized. EXPERIMENTAL DESIGN: We have employed integrated genomic profiling approaches on CLL cases with and without del11q to identify 11q-relevant genes. RESULTS: We have identified differential expression of the insulin receptor (INSR) in CLL, including high-level INSR expression in the majority of CLL with del11q. High INSR mRNA expression in 11q CLL (∼10-fold higher mean levels than other genomic categories) was confirmed by quantitative PCR in 247 CLL cases. INSR protein measurements in 257 CLL cases through flow cytometry, compared with measurements in normal CD19(+) B cells and monocytes, confirmed that a subset of CLL aberrantly expresses high INSR levels. INSR stimulation by insulin in CLL cells ex vivo resulted in the activation of canonical INSR signaling pathways, including the AKT-mTOR and Ras/Raf/Erk pathways, and INSR activation partially abrogated spontaneous CLL cell apoptosis ex vivo. Higher INSR levels correlated with shorter time to first therapy and shorter overall survival (OS). In bivariate analysis, INSR expression predicted for rapid initial disease progression and shorter OS in ZAP-70-low/negative CLL. Finally, in multivariate analysis (ZAP-70 status, IgV(H) status, and INSR expression), we detected elevated HRs and trends for short OS for CLL cases with high INSR expression (analyzed inclusive or exclusive of cases with del11q). CONCLUSIONS: Our aggregate biochemical and clinical outcome data suggest biologically meaningful elevated INSR expression in a substantial subset of all CLL cases, including many cases with del11q.

Rational design of 6-(2,4-diaminopyrimidinyl)-1,4-benzoxazin-3-ones as small molecule renin inhibitors.

We report the design and synthesis of a series of 6-(2,4-diaminopyrimidinyl)-1,4-benzoxazin-3-ones as orally bioavailable small molecule inhibitors of renin. Compounds with a 2-methyl-2-aryl substitution pattern exhibit potent renin inhibition and good permeability, solubility, and metabolic stability. Oral bioavailability was found to be dependent on metabolic clearance and cellular permeability, and was optimized through modulation of the sidechain that binds in the S3(sp) subsite.

Metabolic aromatization of N-alkyl-1,2,3,4-tetrahydroquinoline substructures to quinolinium by human liver microsomes and horseradish peroxidase.

Metabolic aromatization of xenobiotics is an unusual reaction with some documented examples. For instance, the oxidation of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine to the neurotoxic pyridinium ion metabolite 1-methyl-4-phenylpyridinium by monoamine oxidase (MAO) B in the brain has been of interest to a number of investigators. It has also been reported that although the aromatization of N-methyl-tetrahydroisoquinoline occurs with MAO B, the metabolism does not proceed for its isomer, N-methyl-tetrahydroquinoline, by the same enzyme. The aromatization of an N-alkyl-tetrahydroquinoline substructure was identified during in vitro metabolite profiling of compound A, which was designed as a potent renin inhibitor for the treatment of hypertension. The N-alkylquinolinium metabolite of compound A was identified by liquid chromatography-tandem mass spectrometry of human liver microsomal incubates and proton NMR of the isolated metabolite. Further in vitro metabolism studies with a commercially available chemical (compound B), containing the same substructure, also generated an N-alkylquinolinium metabolite. In vitro cytochrome P450 (P450) reaction phenotyping of compound A revealed that the metabolism was catalyzed exclusively by CYP3A4. Although compound B was a substrate for several P450 isoforms, its quinolinium metabolite was also generated predominantly by CYP3A4. Neither compound A nor compound B was a substrate of MAOs. The quinolinium metabolites were readily produced by horseradish peroxidase, suggesting that aromatization of the N-alkyltetrahydroquinoline could occur via a mechanism involving single electron transfer from nitrogen. Although dihydro intermediates from the tetrahydroquinoline substrates were not observed in the formation of quinolinium metabolites, cyanide trapping results indicated the occurrence of iminium intermediates.