Project description:Mice lacking the p27Kip1 Cdk inhibitor (Cdkn1b) exhibit increased susceptibility to lymphomas from the Maloney murine leukemia virus (M-MuLV), and exhibit a high frequency of viral integrations at Xpcl1 (Kis2), a locus on the X-chromosome. Xpcl1 encodes miR-106a~363, a cluster of microRNAs that are expressed in response to adjacent retroviral integrations. We report the first large-scale profile of microRNA expression in MuLV-induced lymphomas, in combination with microarray gene expression analysis. The source material was T-cell lymphomas induced by M-MuLV in p27Kip1 knockout mice and normal thymus. Surprisingly, the overall levels of miRNA expression were equivalent in lymphomas and normal thymus. Nonetheless, the expression of specific microRNAs was altered in tumors. The miR-106a~363 miRNA were over-expressed in lymphomas, particularly those with viral integrations at the Xpcl1 locus. In contrast, p27Kip1 deletion itself was associated with a different pattern of microRNA expression. Gene expression was dramatically altered in lymphomas, yet paralleled data from T-cell lymphomas induced by other mechanisms. Genes with altered expression in association with the p27Kip1 null genotype were of similar functional classes to those associated with Xpcl1 integration, but with the opposite pattern of expression. Thus, the effect of p27Kip1 deletion may be to oppose an anti-oncogenic effect of Xpcl1 rather than enhancing its oncogenic functions. A subset of miR-106a~363 target genes was consistently reduced in lymphomas with Xpcl1 integrations, particularly genes with cell cycle and immune functions. We identify four predicted target genes of miR-106a~363 miRNA, including N-Myc (Mycn), and the TGF-beta receptor (Tgfbr2) using 3'UTR reporter assays. Still, bioinformatic miRNA target predictions were poor predictors of altered gene expression in lymphomas with Xpcl1 integration. Confirmation of miR- 106a~363 gene targeting relevant to the tumor phenotype requires in vivo validation, because only a subset of predicted targets are consistently reduced in tumors that overexpress miR- 106a~363.

Project description:The hallmark of follicular lymphoma (FL) is the t(14;18) chromosomal translocation. However, constitutive expression of anti-apoptotic Bcl-2 alone is insufficient for lymphomagenesis and subsequent molecular hits are required. We explored the role of microRNA (miRNA or miR) in the biology of FL by generating miRNA profiles of enriched sorted grade 1 and 2 FL tumor cells derived from 18 patients compared with enriched germinal center B-cells derived from seven follicular hyperplasia (FH). Expression levels of 851 human miRs were assayed and 133 miRs were significantly differentially expressed in FL tumor cells. The expression of 44 miRs in three major groups generated a unique FL signature. MiRs in group 1 were increased in FL (miR-193-5p, -193b*, -345, -513b, -574-3p, -584, -663, -1287, -1295, and -1471). Group 2 was increased in the majority of FL cases but showed lower levels of expression in a subset of FL (let-7a, let-7f, miR-7-1*, -9, -9*, -20a, -20b, -30b, -96, -98, -194, -195, -221*, -374a, -451, -454, -502-3p, -532-3p, -574-3p, -664*, -1274a, -1274b, and -1260). MiR group 3 was decreased in FL (miR-17*, -30a, 33a, 106a*, -141, 202, -205, -222, 301b, -431*, and -570). Two patterns within FL were detected, largely due to the variable expression of group 2 miRs. The pattern with higher expression of group 2 miRs was associated with complete response to chemotherapy. Gene expression analysis of 199 genes related to lymphoma and tumor development performed in tandem indicated differential expression of 47 genes in FL including increased expression of AKT-1, PRKCE, IL4R, DROSHA, and MAPK1; and decreased expression of CHEK1, RAD51, CDKN1A, SOCS2, KLF4, BLIMP1 and IRF4. Functional studies provide evidence that miR-20a and -20b target CDKN1A/p21, miR-194 targets SOCS2, and miR-301b targets MAPK1 in FL, affecting cell proliferation and potentially contributing to lymphomagenesis. These findings suggest a role for aberrant miRNA expression in the biology of FL with prognostic and mechanistic implications. miRNA profiling was performed using Agilent miRNA array platform with RNAs isolated from sorted follicular lymphoma B cells and follicular hyperplasia B cells.

Project description:The hallmark of follicular lymphoma (FL) is the t(14;18) chromosomal translocation. However, constitutive expression of anti-apoptotic Bcl-2 alone is insufficient for lymphomagenesis and subsequent molecular hits are required. We explored the role of microRNA (miRNA or miR) in the biology of FL by generating miRNA profiles of enriched sorted grade 1 and 2 FL tumor cells derived from 18 patients compared with enriched germinal center B-cells derived from seven follicular hyperplasia (FH). Expression levels of 851 human miRs were assayed and 133 miRs were significantly differentially expressed in FL tumor cells. The expression of 44 miRs in three major groups generated a unique FL signature. MiRs in group 1 were increased in FL (miR-193-5p, -193b*, -345, -513b, -574-3p, -584, -663, -1287, -1295, and -1471). Group 2 was increased in the majority of FL cases but showed lower levels of expression in a subset of FL (let-7a, let-7f, miR-7-1*, -9, -9*, -20a, -20b, -30b, -96, -98, -194, -195, -221*, -374a, -451, -454, -502-3p, -532-3p, -574-3p, -664*, -1274a, -1274b, and -1260). MiR group 3 was decreased in FL (miR-17*, -30a, 33a, 106a*, -141, 202, -205, -222, 301b, -431*, and -570). Two patterns within FL were detected, largely due to the variable expression of group 2 miRs. The pattern with higher expression of group 2 miRs was associated with complete response to chemotherapy. Gene expression analysis of 199 genes related to lymphoma and tumor development performed in tandem indicated differential expression of 47 genes in FL including increased expression of AKT-1, PRKCE, IL4R, DROSHA, and MAPK1; and decreased expression of CHEK1, RAD51, CDKN1A, SOCS2, KLF4, BLIMP1 and IRF4. Functional studies provide evidence that miR-20a and -20b target CDKN1A/p21, miR-194 targets SOCS2, and miR-301b targets MAPK1 in FL, affecting cell proliferation and potentially contributing to lymphomagenesis. These findings suggest a role for aberrant miRNA expression in the biology of FL with prognostic and mechanistic implications.

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Comparative gene expression profiling of cutaneous B cell lymphomas

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