Variability in the degree of expression of phosphorylated IkappaBalpha in chronic lymphocytic leukemia cases with nodal involvement.
Journal - Clinical cancer research : an official journal of the American Association for Cancer Research (United States )
PURPOSE: Based on previous preliminary observations, we hypothesize that the molecular and clinical variability of chronic lymphocytic leukemia (CLL) reflects differences in the degree of nuclear factor (NF)-kappaB activation, as determined by the expression of phosphorylated IkappaBalpha (p-IkappaBalpha). EXPERIMENTAL DESIGN: The expression profile (mRNA and protein expression) was analyzed with the Centro Nacional de Investigaciones Oncologicas Oncochip, a cDNA microarray containing 6386 cancer-related genes, and a tissue microarray (TMA). The results were correlated with the IgV(H) mutational status, ZAP-70 expression, cytogenetic alterations, and clinical outcome. RESULTS: We found correlations between the presence of p-IkappaBalpha, a surrogate marker of NF-kappaB activation, and changes in the expression profile (mRNA and protein expression) and clinical outcome in a series of CLL cases with lymph node involvement. Activation of NF-kappaB, as determined by the expression of p-IkappaBalpha, was associated with the expression of a set of genes comprising key genes involved in the control of B-cell receptor signaling, signal transduction, and apoptosis, including SYK, LYN, BCL2, CCR7, BTK, PIK3CD, and others. Cases with increased expression of p-IkappaBalpha showed longer overall survival than cases with lower expression. A Cox regression model was derived to estimate some parameters of prognostic interest: IgV(H) mutational status, ZAP-70, and p-IkappaBalpha expression. The multivariate analysis disclosed p-IkappaBalpha and ZAP-70 expression as independent prognostic factors of survival. CONCLUSIONS: A variable degree of activation of NF-kappaB, as determined by the expression of p-IkappaBalpha, is an identifiable event in CLL, and is correlated with changes in the expression profile and overall survival.
|ISSN : ||1078-0432|
|Mesh Heading : ||Adult Aged Female Humans I-kappa B Proteins Leukemia, Lymphocytic, Chronic, B-Cell Lymph Nodes Male Middle Aged Oligonucleotide Array Sequence Analysis Phosphorylation Prognosis RNA, Messenger Survival Analysis biosynthesis|
|Mesh Heading Relevant : ||Gene Expression Profiling biosynthesis metabolism genetics pathology pathology|
Identification of Surrogate Prognostic Markers and Genes Implicated in Immunoglobulin Gene (IgVH) Somatic Hypermutation in Small B-Cell Lymphomas.
Journal - ASH Annual Meeting Abstracts
Immunoglobulin (Ig) gene somatic hypermutation (SHM) is a prognosticfactor in small B-cell lymphomas, as demonstrated by studiesreporting that hypermutated chronic lymphocytic leukemia (CLL)and splenic marginal zone lymphoma (SMZL) cases show a betterprognosis, while hypermutated mantle cell lymphoma (MCL) casesdisplay specific clinicopathological features (leukemic course,increased survival).
However both the mechanisms and markers of SHM are poorly characterized,with the partial exception of the role of the genes ZAP70 andAID. With the purpose of identifying SHM surrogate markers insmall B-cell lymphomas, we analyzed IgVH mutational status andexpression profiles of 93 small B-cell lymphoma patient samplesincluding SMZL (24 cases), MCL (33 cases) and CLL (36 cases).Patients were classified into two groups: high SHM (>5% mutations)and low SHM (<5% mutations). T-test analysis with 100,000permutations was performed and 39 genes were identified whoseexpression is significantly different (p<0.005, FDR<0.05)between cases with high and low SHM burdens.
To dissect the molecular mechanisms of Ig somatic hypermutationand validate the observed findings, SHM was induced in a modelsystem and compared to results in patient samples. The BL2 cellline was used, and SHM was induced by treating the cells withIL4 and CD40. After 24 hours, active SHM was confirmed by westernblot using an anti-AID monoclonal antibody on treated and untreatedcells. These same cells were analyzed using microarrays, toidentify the genes that were induced or downregulated duringthe SHM activation. A total of 29 genes (18 upregulated and11 downregulated) were identified which are significantly differentiallyexpressed in the cell line model during induction of SHM (expressionchange >0.4 Log2 scale) and are also differentially expressedbetween cases with high and low SHM (p<0.001, FDR<0.1).In both analyses, the upregulated genes are implicated in transcription,DNA repair and replication and chromosome maintenance, correlatingwell with previous hypotheses indicating that active transcriptionis necessary for SHM. Based on these observations, a group of10 key genes, implicated in DNA repair, replication and transcription,were selected and protein expression was analyzed in a set oftissue microrrays containing 150 paraffin embedded small B-celllymphoma cases, for which clinical data is available and SHMstatus is known. These proteins may provide a surrogate markerfor prognosis and/or analysis of IgVH SHM in patient samplesusing paraffin-embedded tissue samples.
Variability in the Degree of Expression of Phosphorylated IB in Chronic Lymphocytic Leukemia Cases With Nodal Involvement
Journal - Clinical Cancer Research
Purpose: Based on previous preliminary observations, we hypothesizethat the molecular and clinical variability of chronic lymphocyticleukemia (CLL) reflects differences in the degree of nuclearfactor (NF)-B activation, as determined by the expression ofphosphorylated IB (p-IB).Experimental Design: The expression profile (mRNA and proteinexpression) was analyzed with the Centro Nacional de InvestigacionesOncológicas Oncochip, a cDNA microarray containing 6386cancer-related genes, and a tissue microarray (TMA). The resultswere correlated with the IgVH mutational status, ZAP-70 expression,cytogenetic alterations, and clinical outcome.Results: We found correlations between the presence of p-IB,a surrogate marker of NF-B activation, and changes in the expressionprofile (mRNA and protein expression) and clinical outcome ina series of CLL cases with lymph node involvement. Activationof NF-B, as determined by the expression of p-IB, was associatedwith the expression of a set of genes comprising key genes involvedin the control of B-cell receptor signaling, signal transduction,and apoptosis, including SYK, LYN, BCL2, CCR7, BTK, PIK3CD,and others. Cases with increased expression of p-IB showed longeroverall survival than cases with lower expression. A Cox regressionmodel was derived to estimate some parameters of prognosticinterest: IgVH mutational status, ZAP-70, and p-IB expression.The multivariate analysis disclosed p-IB and ZAP-70 expressionas independent prognostic factors of survival.Conclusions: A variable degree of activation of NF-B, as determinedby the expression of p-IB, is an identifiable event in CLL,and is correlated with changes in the expression profile andoverall survival.