Genetic lesions of the TRAF3 and MAP3K14 genes in classical Hodgkin lymphoma.

Hodgkin and Reed/Sternberg (HRS) cells in classical Hodgkin lymphoma (cHL) show constitutive activation of nuclear factor (NF)-κB. Several genetic lesions contribute to this deregulated NF-κB activity. Here, we analysed two further NF-κB regulators for genetic lesions, the inhibitory factor TRAF3 and the key signalling component of the alternative NF-κB pathway, MAP3K14 (NIK). Single nucleotide polymorphism (SNP) array analysis of cHL cell lines revealed a uniparental disomy of the long arm of chromosome 14 associated with a biallelic deletion of TRAF3 located on this chromosome in cell line U-HO1. Cloning of the deletion breakpoint showed a 123 371 bp deletion. No inactivating mutations of TRAF3 were found in six other cHL cell lines or in microdissected HRS cells from seven cHL. However, in primary cHL samples interphase cytogenetic analyses revealed signal patterns indicating monoallelic deletion of TRAF3 in 3/20 other cases. SNP array analysis revealed a gain of copy number for MAP3K14 in three cHL cell lines. Gains of MAP3K14 were detected in 5/16 cases of primary cHL. In conclusion, in rare instances, HRS cells harbour inactivating mutations of the TRAF3 gene and recurrently show gains of MAP3K14, indicating that more components of NF-κB signalling show genetic lesions in HRS cells than previously known.

Rare occurrence of biallelic CYLD gene mutations in classical Hodgkin lymphoma.

Survival of the malignant Hodgkin and Reed/Sternberg (HRS) cells in classical Hodgkin lymphoma (cHL) is dependent on constitutive activation of the nuclear factor kappaB (NF-kappaB) transcription factor. The deubiquitinating enzyme CYLD is a negative regulator of NF-kappaB and known to function as a tumor suppressor. To determine whether CYLD mutations play a role in cHL pathogenesis, we sequenced the gene in cHL cell lines and microdissected HRS cells obtained from lymph-node biopsies. A biallelic inactivation by mutations was found in the cHL cell-line KM-H2. However, the other seven cHL cell lines analyzed and HRS cells of 10 primary cHL cases did not show any mutations. By interphase cytogenetics, a (sub)clonal biallelic CYLD deletion was observed by interphase cytogenetics in 1 of 29 primary cHL, whereas signal patterns indicating decreased CYLD copy numbers were observed in a total of 10 of 29 primary cases. Our results suggest that biallelic CYLD mutations are rarely involved in cHL pathogenesis. Nevertheless, it is remarkable that KM-H2 cells, besides the CYLD mutations, also carry inactivating mutations in the genes of two other NF-kappaB inhibitors, that is, NFKBIA and TNFAIP3, exemplifying that multiple lesions in regulators of this signaling pathway can likely cooperatively contribute to the strong NF-kappaB activity of these cells.