BCL2 is deregulated in diffuse large B-cell lymphoma (DLBCL) by the t(14;18) translocation, gene amplification and/or nuclear factor-kB signaling. RNA-seq data have recently shown that BCL2 is the most highly mutated gene in germinal center B-cell (GCB) DLBCL. We have sequenced BCL2 in 298 primary DLBCL biopsies, 131 additional non-Hodgkin lymphoma biopsies, 24 DLBCL cell lines and 51 germline DNAs. We found frequent BCL2 mutations in follicular lymphoma (FL) and GCB DLBCL, but low levels of BCL2 mutations in activated B-cell DLBCL, mantle cell lymphoma, small lymphocytic leukemia and peripheral T-cell lymphoma. We found no BCL2 mutations in GC centroblasts. Many mutations were non-synonymous; they were preferentially located in the flexible loop domain, with few in BCL2-homology domains. An elevated transition/transversions ratio supports that the mutations result from somatic hypermutation. BCL2 translocations correlate with, and are likely important in acquisition of, additional BCL2 mutations in GCB DLBCL and FL. DLBCL mutations were not independently associated with survival. Although previous studies of BCL2 mutations in FL have reported mutations to result in pseudo-negative BCL2 protein expression, we find this rare in de-novo DLBCL.Leukemia ( BCL2, discovered because of its involvement in t(14;18) in follicular lymphoma (FL), 3 has a central role in the inhibition of apoptosis. 4 BCL2 is normally transiently expressed during B-cell maturation. The t(14;18) translocation causes constitutive overexpression of BCL2 by juxtaposing it to immunoglobulin heavy chain gene enhancer elements. This translocation is found in B20% of DLBCL, 5 most often in the GCB subtype of DLBCL. 6 Other mechanisms of BCL2 deregulation, more often observed in ABC DLBCLs, include amplification of the BCL2 gene or its transcriptional upregulation through constitutive activation of the nuclear factor-kB pathway. 7 Saito et al. 8 reported that the BCL2 promoter can also be aberrantly hypermutated in DLBCL, which may prevent its inhibition by MIZ1 and BCL6. 8 They found a high number of mutations in BCL2 and suggested that the mutations described were the result of somatic hypermutation (SHM). Mutations in BCL2 have been shown to cause false-negative protein expression results in immunohistochemistry assays in FL; 9,10 however, no large study has so far investigated whether this occurs in DLBCL.

The binding of the papillomavirus E6 protein to E6AP and the induction of p53 degradation are common features of high-risk genital human papillomaviruses (HPV); cutaneous HPVs, on the other hand, lack these capacities. Nevertheless, several cutaneous HPV types of the β-genus, such as HPV38 are associated with tumor formation when combined with genetic predisposition, immunosuppression, or UV exposure. In an animal model system, the cottontail rabbit papillomavirus (CRPV) rapidly induces skin cancer without additional cofactors, and CRPVE6 and E7 immortalize rabbit keratinocytes in vitro. However, CRPVE6 neither interacts with E6AP and p53 nor does it induce p53 degradation. In this study, we show that the interaction of CRPVE6, or HPV38E6, with the histone acetyltransferase p300 is crucial to inhibit the ability of p53 to induce apoptosis. Strikingly, E6 mutants deficient for p300 binding are incapable of preventing p53 acetylation, p53-dependent transcription, and apoptosis induction. Moreover, E6 mutants deficient for p300 binding cannot contribute to HPV38-induced immortalization of human keratinocytes or CRPV-induced tumor formation. Our findings highlight changes in the p53 acetylation status mediated by the viral E6 protein as a crucial requirement in the ability of high-risk cutaneous papillomaviruses to immortalize primary keratinocytes and induce tumors.

No abstract