Identification of a novel IGH-MMSET fusion transcript in a human myeloma cell line with the t(4;14)(p16·3;q32) chromosomal translocation

The histone methyltransferase, NSD2, enhances androgen receptor-mediated transcription

In this study, we discovered that NSD2 specifically interacts with the DNA-binding domain of androgen receptor (AR) via its HMG domain, and the nuclear translocation of both NSD2 and AR is enhanced in the presence of ligand. Furthermore, we also demonstrated that the over expression of NSD2, but not of NSD2 (DeltaSET) HMT-activity defective mutant, enhanced the mRNA level of PSA in a dose-dependent manner. A chromatin immunoprecipitation assay showed that NSD2 protein is recruited to the enhancer region of the PSA gene by AR in an agonist-enhanced manner. Taken together, these results uncover a potential role for NSD2 in AR-mediated transcription, implicating NSD2 in prostate carcinogenesis.

Ten years and counting: so what do we know about t(4;14)(p16;q32) multiple myeloma

Multiple myeloma is a genetically heterogenous disease with a wide variety of characterized genetic aberrations. Until recently, the impact of these aberrations on patient outcome was not known. However, in the last 5-10 years, several genetic markers have been linked to patient outcome. One of the strongest predictors of outcome identified to date is t(4;14)(p16;q32). Although this translocation is tightly linked to chromosome 13 deletions, another poor prognosis marker, it is becoming apparent that the translocation and not the deletion of 13 is the important factor. Unfortunately, despite the known association with outcome, an understanding of the mechanism(s) whereby the translocation contributes to developing and maintaining this aggressive form of myeloma remains elusive.

Distinguishing primary and secondary translocations in multiple myeloma

Multiple myeloma (MM) is a malignant post-germinal center tumor of somatically-mutated, isotype-switched plasma cells that accumulate in the bone marrow. It often is preceded by a stable pre-malignant tumor called monoclonal gammopathy of undetermined significance (MGUS), which can sporadically progress to MM. Five recurrent primary translocations involving the immunoglobulin heavy chain (IgH) locus on chromosome 14q32 have been identified in MGUS and MM tumors. The five partner loci include 11q13, 6p21, 4p16, 16q23, and 20q12, with corresponding dysregulation of CYCLIN D1, CYCLIN D3, FGFR3/MMSET, c-MAF, and MAFB, respectively, by strong enhancers in the IgH locus. The five recurrent translocations, which are present in 40% of MM tumors, typically are simple reciprocal translocations, mostly having breakpoints within or near IgH switch regions but sometimes within or near VDJ or JH sequences. It is thought that these translocations are caused by aberrant IgH switch recombination, and possibly by aberrant somatic hypermutation in germinal center B cells, thus providing an early and perhaps initiating event in transformation. A MYC gene is dysregulated by complex translocations and insertions as a very late event during the progression of MM tumors. Since the IgH switch recombination and somatic hypermutation mechanism are turned off in plasma cells and plasma cell tumors, the MYC rearrangements are thought to be mediated by unknown mechanisms that contribute to structural genomic instability in all kinds of tumors. These rearrangements, which often but not always juxtapose MYC near one of the strong immunoglobulin enhancers, provide a paradigm for secondary translocations. It is hypothesized that secondary translocations not involving a MYC gene can occur at any stage of tumorigenesis, including in pre-malignant MGUS tumor cells.