Distinctive gene expression pattern in VH3-21 utilizing B-cell chronic lymphocytic leukemia

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Abstract
The usage of the immunoglobulin (Ig) VH3-21 gene is associated with poor prognosis in B-cell chronic lymphocytic leukemia (B-CLL) despite VH gene mutation status. Many VH3-21+ patients also display restricted heavy- and light-chain Ig gene rearrangements, implying a role of antigen selection in disease development. To explore the specific phenotypic/genotypic features among VH3-21+ B-CLLs, we compared gene expression patterns in 15 VH3-21+ and 24 non-VH3-21 patients (11 with unmutated and 13 with mutated VH genes) using Affymetrix microarray analysis (∼12 500 genes). A distinct expression profile was identified for VH3-21+ patients in contrast to the Ig-unmutated and -mutated groups. By applying different algorithms, the data enabled an efficient class discrimination of the VH3-21+ subset based on 27 or 57 genes. A set of genes was sorted out which, using different analytical methods, consistently gave a distinction between VH3-21+ and non-VH3-21 samples. Several of these genes are involved in regulation of DNA replication/cell-cycle control, transcription and protein kinase activity, which may render the VH3-21+ cells with a higher proliferative drive. However, no clear evidence of increased B-cell receptor signaling was found in the VH3-21+ group. Altogether, our identification of a specific VH3-21 profile may provide insights into the pathogenesis of the VH3-21+ subgroup. (Blood. 2005;106:681-689)
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