Waldenstrom's Macroglobulinemia patients: expression and aCGH data

Waldenstrms macroglobulinemia (WM) is a distinct clinicobiological entity defined as a B-cell neoplasm characterized by a lymphoplasmacytic infiltrate in the bone marrow and immunoglobulin M paraprotein production. Cytogenetic analysis is limited by the difficulty in obtaining tumor metaphases and the genetic basis of the disease remains poorly defined. We performed a comprehensive analysis in 42 WM patients by using high-resolution array-based comparative genomic hybridization with the Human Genome 244A microarray. Overall, 83% of samples have chromosomal abnormalities, with a median of three abnormalities per patient (range 0 to 27). The most common abnormality was 6q deletion (40%) and four non-overlapped minimal deleted regions (MDR) were identified. Gain of 6p was the second most common abnormality (17%) and its presence was always concomitant with 6q loss. An interstitial MDR was delineated at 13q14 including MIRN15A and MIRN16-1 in 10% of patients. Other recurrent deletions were 7q22, 8p, 11q22-q23, 11q23-q24 and 17p11-p13 (7% each). Copy gains were identified in chromosomes 18 (17%), 4 (12%), 3 (10%), 8q (10%) and Xq27.1-q28 (10%). To note, we reported biallelic deletions and/or inactivating mutations with uniparental disomy in TRAF3 and TNFAIP3, two negative regulators of the NF-kB signaling pathway. Furthermore, we confirmed the association between TRAF3 inactivation and increased transcriptional activity of NF-kB target genes. Mutational activation of the NF-kB pathway, which is normally activated by ligand-receptor interactions within the bone marrow microenvironment, highlight its biologic importance, and suggest a therapeutic role for inhibitors of NF-KB pathway activation in the treatment of Waldenstrms macroglobulinemia.

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Braggio E, Keats JJ, Leleu X, Van Wier S, Jimenez-Zepeda VH, Valdez R, Schop RF, Price-Troska T, Henderson K, Sacco A, Azab F, Greipp P, Gertz M, Hayman S, Rajkumar SV, Carpten J, Chesi M, Barrett M, Stewart AK, Dogan A, Bergsagel PL, Ghobrial IM, Fonseca R