title: A new fusion gene TPM3-ALK in anaplastic large cell lymphoma created by a (1;2)(q25;p23) translocation.
abstract: Anaplastic large cell lymphomas (ALCL) are frequently associated with the t(2;5)(p23;q35). This translocation fuses the nucleophosmin (NPM) gene at 5q35, which encodes a nucleolar protein involved in shuttling ribonucleoproteins from the cytoplasm to the nucleus, to the anaplastic lymphoma kinase (ALK) gene at 2p23, encoding a tyrosine kinase receptor. In this report, we describe a typical case of ALCL whose malignant cells exhibited a novel (1;2)(q25;p23) translocation. These cells expressed ALK protein, but, in contrast to t(2;5)-positive ALCL (which show cytoplasmic, nuclear, and nucleolar staining), labeling was restricted to the malignant cell cytoplasm. Using a polymerase chain reaction (PCR)-based technique to walk on chromosome 2 from the known ALK gene across the breakpoint, we showed that the gene involved at 1q25 is TPM3, encoding a nonmuscular tropomyosin. We subsequently identified, using reverse transcription-PCR analysis of cases showing similar ALK cytoplasm-restricted staining, fusion of the ALK and TPM3 genes in 2 other cases of ALCL. The TPM3 gene has been previously found in papillary thyroid carcinomas as a fusion partner with the TRK kinase gene. We showed that TPM3 is constitutively expressed in lymphoid cell lines, suggesting that, in these t(1;2)-bearing ALCL cases, the TPM3 gene contributes an active promoter for ALK expression. Activation of the ALK catalytic domain probably results from homodimerization of the hybrid protein TPM3-ALK, through the TPM3 protein-protein interaction domain. The present cases of ALCL associated with a novel t(1;2)(q25;p23) demonstrate that at least one fusion partner other than NPM can activate the intracytoplasmic domain of the ALK kinase.
authors.affiliation: Department of Pathology, Hematology Laboratory, and UPCM-ERS 1590 CNRS, CHU Purpan, Toulouse, France.
authors.forename: L
authors.initials: L
authors.lastname: Lamant
authors.forename: N
authors.initials: N
authors.lastname: Dastugue
authors.forename: K
authors.initials: K
authors.lastname: Pulford
authors.forename: G
authors.initials: G
authors.lastname: Delsol
authors.forename: B
authors.initials: B
authors.lastname: Mariamé
mesh_terms: D000077548:Anaplastic Lymphoma Kinase; D001483:Base Sequence; D002874:Chromosome Mapping; D002878:Chromosomes, Human, Pair 1; D002889:Chromosomes, Human, Pair 2; D017931:DNA Primers; D006801:Humans; D007621:Karyotyping; D017728:Lymphoma, Large-Cell, Anaplastic / Q000235:genetics* / Q000473:pathology; D008969:Molecular Sequence Data; D015514:Oncogene Proteins, Fusion / Q000235:genetics*; D011505:Protein-Tyrosine Kinases / Q000235:genetics*; D020794:Receptor Protein-Tyrosine Kinases; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014178:Translocation, Genetic; D014335:Tropomyosin / Q000235:genetics*
chemical_list: D017931:DNA Primers; D015514:Oncogene Proteins, Fusion; D014335:Tropomyosin; C000626173:ALK protein, human; D000077548:Anaplastic Lymphoma Kinase; D011505:Protein-Tyrosine Kinases; D020794:Receptor Protein-Tyrosine Kinases