CpG Island Methylation and Expression of the Secreted Frizzled-Related Protein Gene Family in Chronic Lymphocytic Leukemia

Abstract Abstract 3489 Telomeres are a repetitive DNA sequences associated with a protein complex named shelterin that protect chromosome ends. Two types of mechanisms maintain telomere in cancer cells. The first involves telomerase an enzyme able to copy the telomeric motif that consists of three principal subunits, including the telomerase reverse transcriptase hTERT. The second, named ALT (Alternative Lengthening of Telomere), corresponds to the recombination between telomeres that involves notably a complex formed by the topoisomerase III alpha (hTopoIIIa), BLM, RMI1 and RMI2. Little is known about the involvement of the ALT mechanism in B-chronic lymphocytic leukemia (B-CLL). In fact this leukemic disease shows low telomerase activity, shelterin defect and telomeric dysfunction. In an effort to characterize ALT cells from 31 B-CLL patients, we analyzed their telomere length and telomerase activity. B-CLL patients showed almost no hTERT transcript (detected in three cases), low telomerase activity (detected in 7 cases) and a telomere average size ranging from 3 to 10 kb. Moreover, a strong deregulation of genes encoding three shelterin proteins, TRF1, TRF2, Pot1, and an at least two fold downregulation of hTopoIIIa gene expression in 21 cases were observed, suggesting the presence of a telomere maintenance dysfunction affecting both mechanisms, telomerase dependent and ALT. CpG island methylation has been mapped for both promoters and if hTERT shows a disseminated methylation profile in 22 patients, for hTopoIIIα we identified nine CpG upstream the minimal promoter, being methylated in 19 of our 31 analyzed patients. We then performed luciferase experiments and we showed that methylation in this 9 CpG induced a strong inhibition of hTopoIIIa transcription. Finally we correlated telomere length and hTopoIIIa methylation status as we observed that 25.4% of the hTopoIIIa promoters were methylated in patients with shorter chromosomes and only 11.1 % were methylated in patients with longer telomeres (p<0.0025). As nearly no telomerase activity have been detected in our patients and as downregulation of hTopoIIIa could increase recombination rate between sister chromatid, methylation of hTERT and hTopoIIIa promoter CpG islands may lead to telomere dysfunction and increased genetic instability in B-CLL. Disclosures: No relevant conflicts of interest to declare.

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CpG island methylation patterns in chronic lymphocytic leukemia

Leukemia & Lymphoma ◽

10.1080/10428190902756594 ◽

2009 ◽

Vol 50 (3) ◽

pp. 419-426 ◽

Cited By ~ 22

Author(s):

Barbara Seeliger ◽

Stefan Wilop ◽

Rainhardt Osieka ◽

Oliver Galm ◽

Edgar Jost

Keyword(s):

Chronic Lymphocytic Leukemia ◽

Cpg Island ◽

Lymphocytic Leukemia ◽

Cpg Island Methylation ◽

Methylation Patterns

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CpG island methylation and promoter usage in the parathyroid hormone-related protein gene of cultured lung cells

Biochimica et Biophysica Acta (BBA) - Gene Structure and Expression ◽

10.1016/s0167-4781(97)00031-6 ◽

1997 ◽

Vol 1352 (3) ◽

pp. 303-310 ◽

Cited By ~ 5

Author(s):

Rosalind H Ganderton ◽

Roger S.J Briggs

Keyword(s):

Parathyroid Hormone ◽

Protein Gene ◽

Cpg Island ◽

Lung Cells ◽

Related Protein ◽

Parathyroid Hormone Related Protein ◽

Promoter Usage ◽

Cpg Island Methylation

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Glucocorticoid-induced TNFR-related protein (GITR) ligand modulates cytokine release and NK cell reactivity in chronic lymphocytic leukemia (CLL)

Leukemia ◽

10.1038/leu.2011.313 ◽

2011 ◽

Vol 26 (5) ◽

pp. 991-1000 ◽

Cited By ~ 24

Author(s):

C Buechele ◽

T Baessler ◽

S Wirths ◽

J U Schmohl ◽

B J Schmiedel ◽

...

Keyword(s):

Chronic Lymphocytic Leukemia ◽

Nk Cell ◽

Lymphocytic Leukemia ◽

Cytokine Release ◽

Related Protein ◽

Cell Reactivity

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No evidence for DNA methylation of theATMpromoter CpG island in chronic lymphocytic leukemia

Leukemia & Lymphoma ◽

10.3109/10428194.2011.653640 ◽

2012 ◽

Vol 53 (7) ◽

pp. 1420-1422 ◽

Cited By ~ 2

Author(s):

Thomas Mikeska ◽

Dennis A. Carney ◽

John F. Seymour ◽

Alexander Dobrovic

Keyword(s):

Dna Methylation ◽

Chronic Lymphocytic Leukemia ◽

Cpg Island ◽

Lymphocytic Leukemia

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CpG island methylation of the hTERT promoter is associated with lower telomerase activity in B-cell lymphocytic leukemia

Experimental Hematology ◽

10.1016/s0301-472x(01)00760-3 ◽

2002 ◽

Vol 30 (1) ◽

pp. 26-33 ◽

Cited By ~ 48

Author(s):

O Bechter

Keyword(s):

B Cell ◽

Cpg Island ◽

Telomerase Activity ◽

Lymphocytic Leukemia ◽

Htert Promoter ◽

Cpg Island Methylation

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Methylation Profile of B-Chronic Lymphocytic Leukemia Cells.

Blood ◽

10.1182/blood.v106.11.2951.2951 ◽

2005 ◽

Vol 106 (11) ◽

pp. 2951-2951

Author(s):

Jun Fan ◽

Asou Norio ◽

Masao Matsuoka

Keyword(s):

Dna Methylation ◽

Chronic Lymphocytic Leukemia ◽

Cell Lines ◽

Mammalian Cells ◽

Mononuclear Cells ◽

Cpg Island ◽

Methylation Status ◽

Lymphocytic Leukemia ◽

Dna Hypomethylation ◽

Peripheral Blood Mononuclear

Abstract DNA methylation plays an important role in the development and aging of mammalian cells, and its dysregulation has been frequently observed in cancer cells. The purpose of this study is to investigate the involvement of aberrant DNA methylation in B chronic lymphocytic leukemia (B-CLL) cells. We compared methylation status of B-CLL cells isolated from patients with that of normal CD19+ cells isolated from health donors by methylated CpG island amplification/representative difference analysis method. 5 hypermethylated and 27 hypomethylated DNA regions were identified in B-CLL sample. Among the 27 hypomethylated regions, 5 located on chromosome 9q34, 3 on 10q25-26 and 4 on 19q13. Methylation status was confirmed by sequencing using sodium bisulfite-treated DNA samples. By comparing DNA samples from same patients at different clinical stages, we found that lower methylation density in these regions is linked with disease progression. Expression of 15 genes surrounding hypomethylated regions was studied by RT-PCR. Expression of laminin beta3 gene and melanotransferrin gene was found to be upregulated in all B-CLL cell lines as well as lymphoma cell lines comparing with normal CD19+ peripheral blood mononuclear cells. B-cell CLL/lymphoma 11b gene showed increased expression in only 2 B-CLL cell lines. For other genes, no transcriptional change was found regardless of changed DNA methylation. This study showed the predominance of DNA hypomethylation in B-CLL cells compared with hypermethylation. Hypomethylated regions clustered in a limited number of chromosomes and methylation density appeared to be inversely correlated with disease progress. Figure Figure

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Distinctive IgVH Gene Segments Usage and Mutation Status in Chinese Patients with Chronic Lymphocytic Leukemia.

Blood ◽

10.1182/blood.v110.11.4708.4708 ◽

2007 ◽

Vol 110 (11) ◽

pp. 4708-4708

Author(s):

Lijuan Chen ◽

Yaping Zhang ◽

Wenjuuan Zheng ◽

Jianyong Li ◽

Changgeng Ruan

Keyword(s):

Chronic Lymphocytic Leukemia ◽

Gene Family ◽

Gene Families ◽

Lymphocytic Leukemia ◽

Chinese Patients ◽

Chain Gene ◽

Mutation Status ◽

Significant Difference ◽

Variable Heavy ◽

Vh Gene

Abstract Chronic lymphocytic leukemia (CLL) is characterized by the relentless accumulation of monoclonal B cells with the appearance of small mature lymphocytes and a characteristic CD5 and CD19 co-expression immunophenotype. The incidence of CLL in Asian countries is lower than that in the Western ones, where CLL is the most common leukemia. To evaluate the frequency and mutation status of immunoglobulin (Ig) variable heavy chain gene (IgVH) expression in Chinese patients with CLL. We investigated IgVH gene segments usage and mutation status by multiplex RT-PCR in 52 CLL patients, and analyzed the relationship between IgVH somatic mutation status and the expression of CD38, ZAP-70 and CLLU1. 38 patients had mutated IgVH, and 14 had unmutated IgVH. The most frequently expressed VH gene family was found to be VH3 (46.2%) followed by VH4 (40.4%), VH1 (5.8%), VH2 (5.8%) and VH7 (1.9%), with no expression of VH5 and VH6 gene families. VH1-69 and VH3-21 which commonly overused in Western CLL weren’t detected in our cohort. The frequency of IgVH gene families indicates significant difference in Chinese CLL patients compared with Western patients, suggesting involvement of ethnic and/or environmental factors in CLL disease initiation. IgVH gene mutation status was significantly associated with the expression of CD38 and CLLU1. The expression of them may be simple and reliable surrogates for the identification of IgVH mutations. VH gene family usage and mutation status VH family n Mutated VH gene Unmutated VH gene VH1 3 3 0 VH2 3 2 1 VH3 24 19 5 VH4 21 16 5 VH5 0 0 0 VH6 0 0 0 VH7 1 0 1

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The BCL11 gene family: involvement of BCL11A in lymphoid malignancies

Blood ◽

10.1182/blood.v98.12.3413 ◽

2001 ◽

Vol 98 (12) ◽

pp. 3413-3420 ◽

Cited By ~ 192

Author(s):

Ed Satterwhite ◽

Takashi Sonoki ◽

Tony G. Willis ◽

Lana Harder ◽

Rachael Nowak ◽

...

Keyword(s):

B Cells ◽

Gene Family ◽

B Cell ◽

Family Involvement ◽

Cpg Island ◽

Rare Event ◽

Fetal Brain ◽

Chromosomal Translocation ◽

Lymphocytic Leukemia ◽

Lymphoid Malignancies

Abstract Many malignancies of mature B cells are characterized by chromosomal translocations involving the immunoglobulin heavy chain(IGH) locus on chromosome 14q32.3 and result in deregulated expression of the translocated oncogene. t(2;14)(p13;q32.3) is a rare event in B-cell malignancies. In contrast, gains and amplifications of the same region of chromosome 2p13 have been reported in 20% of extranodal B-cell non-Hodgkin lymphomas (B-NHL), in follicular and mediastinal B-NHL, and in Hodgkin disease (HD). It has been suggested that REL, an NF-κB gene family member, mapping within the amplified region, is the pathologic target. However, by molecular cloning of t(2;14)(p13;q32.3) from 3 cases of aggressive B-cell chronic lymphocytic leukemia (CLL)/immunocytoma, this study has shown clustered breakpoints on chromosome 2p13 immediately upstream of a CpG island located about 300 kb telomeric of REL. This CpG island was associated with a Krüppel zinc finger gene (BCL11A), which is normally expressed at high levels only in fetal brain and in germinal center B-cells. There were 3 major RNA isoforms ofBCL11A, differing in the number of carboxy-terminal zinc fingers. All 3 RNA isoforms were deregulated as a consequence of t(2;14)(p13;q32.3). BCL11A was highly conserved, being 95% identical to mouse, chicken, and Xenopus homologues.BCL11A was also highly homologous to another gene(BCL11B) on chromosome 14q32.1. BCL11Acoamplified with REL in B-NHL cases and HD lymphoma cell lines with gains and amplifications of 2p13, suggesting thatBCL11A may be involved in lymphoid malignancies through either chromosomal translocation or amplification.

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