Frequent translocation t(4;14)(p16.3;q32.3) in multiple myeloma is associated with increased expression and activating mutations of fibroblast growth factor receptor 3

Abstract

Dysregulation of oncogenes by translocation to the IgH locus (14q32) is a seminal event in the pathogenesis of B-cell tumours 1 . In multiple myeloma (MM), translocations to the IgH locus have been reported at an incidence of 20-60%. For most translocations, the partner chromosome is unknown (14q+); for the others, a diverse array of chromosomal partners have been identified, with 11q13 (cyclin D1) the only chromosome that is frequently involved [2][3][4][5][6] . Recently, we developed a Southern-blot assay that detects translocation breakpoint fragments in most MM tumours, including those with no translocation detected by conventional karyotyping 6 . In a continuing analysis of translocations in 21 myeloma cell lines and primary tumours, we show that the novel, karyotypically silent translocation t(4;14)(p16.3;q32.3) is present in five lines and at least three of ten primary tumours. The chromosome-4 breakpoints are clustered in a 70-kb region centromeric to the fibroblast growth factor receptor 3 gene (FGFR3), the apparent dysregulated oncogene. Two lines and one primary tumour with this translocation selectively express an FGFR3 allele containing activating mutations identified previously in thanatophoric dwarfism. We propose that after the t(4;14) translocation, somatic mutation during tumour progression frequently generates an FGFR3 protein that is active in the absence of ligand.As described in detail elsewhere 6 , we generated paired probes immediately upstream and downstream of the repetitive sequences in each switch region-for example, 5'Sµ and 3'Sµ probes. By Southern-blot analysis, candidate translocation breakpoint fragments were identified as rearranged fragments that hybridize to only one switch probe. Fig. 1a illustrates a balanced translocation into Sµ, with the 3'Sµ probe detecting the der(14) breakpoint and the 5'Sµ probe detecting the der(4) breakpoint. Using this approach, we cloned one translocation breakpoint fragment involving chromosome 4 from each of five samples: four MM lines (KMS11, H929, OPM2 and JIM3) and one plasma cell leukaemia tumour (PCL-1). In each case, the novel non-Ig sequences at the breakpoint and at one end of the fragment were identical to sequences present in a cosmid contig that is centromeric to the fibroblast growth factor receptor 3 (FGFR3) gene at 4pl6.3 (Fig. 1) probes that were used in Southern-blot analyses to detect and map reciprocal breakpoint fragments for KMS11, H929 and PCL-1 (Fig. 2a-c). For example, as shown in Fig. 2a for the der(4)(5'Sµ) reciprocal breakpoint in KMS11 ( Fig. 1), a 5'Sµ probe detected a rearranged 7.9-kb XbaI fragment (compared to 7.5-kb fragment in placental [P] DNA) and a 4pl6.3 probe (9226 in Fig. 1b) that detects a 13.8-kb germline fragment in the tumour and in placental DNA, co-hybridizes to the 7.9-kb XbaI fragment in KMS11. These results, together with Southern blots using other enzymes, are consistent with the der(4) (5'Sµ) translocation breakpoint occurring near the cloned der(14) (3'Sµ) translocation breakpoint for K...

Dysregulation of cyclin dependent kinase 6 expression in splenic marginal zone lymphoma through chromosome 7q translocations

“…Dysregulation of oncogenes by translocation to an immunoglobulin heavy or light chain locus is a frequent event in the pathogenesis of B-cell malignancies (Korsmeyer, 1992;Rabbitts 1994;Chesi et al, 1997). Translocations may result from aberrant VDJ or class switch recombination, or arise as a consequence of somatic hypermutation (Goossens et al, 1998) or recombinase activating gene (RAG) mediated transposition (Hiom et al, 1998).…”

“…RNA was recovered and cDNA synthesized by standard methods (Chesi et al, 1997). The e ciency of cDNA synthesis was monitored by measuring incorporation of labeled dCTP, and the quality of the cDNA veri®ed by PCR ampli®cation using RNA speci®c primers for a 520 bp fragment of the b 2 -microglobulin gene.…”

AKT activity regulates the ability of mTOR inhibitors to prevent angiogenesis and VEGF expression in multiple myeloma cells

“…In addition, cytokines which promote angiogenesis and are expressed at high levels in myeloma bone marrow also support myeloma cell growth and viability (Dankbar et al, 2000). These angiogenic cytokines overexpressed in myeloma include vascular endothelial growth factor (VEGF) (Bellamy et al, 1999), basic fibroblast growth factor (Chesi et al, 1997) and hepatocyte growth factor (HGF) (Sezer et al, 2001).…”

Nonrandom 4p13 rearrangements of the RhoH/TTF gene, encoding a GTP-binding protein, in non-Hodgkin's lymphoma and multiple myeloma

“…One case of t(4;14) was already described in MM, but with a breakpoint in the 4p16.3 region, implicating the FGFR3 gene, which was shown to be deregulated by juxtaposition to the IgH gene, in this observation (Chesi et al, 1997). Another recurrent chromosome abnormality involving the short arm of chromosome 4 has been recently described, as a dicentric (4;17) chromosome with 4p11-pter/17p11-pter deletion (Callet-Bauchu et al, 1996).…”