title: PML-RARA fusion transcripts in irradiated and normal hematopoietic cells.
abstract: It is believed that two important factors in the genesis of reciprocal chromosomal translocations in malignant cells are the physical proximity of the involved regions and local structural features of the chromatin fiber that make them more susceptible to breakage and rearrangement. In this work we sought to investigate whether PML-RARA fusion transcripts, characteristic of acute promyelocytic leukemia (APL), could be induced by a clastogenic agent in cells known to have, a priori, a favorable spatial distribution of these genes. A lymphoid-cell line, lacking the t(15;17) but having the PML and RARA genes in close proximity in specific phases of the cell cycle, was irradiated with 10 Gy of (60)Co, and the incidence of PML-RARA transcripts was analyzed by a highly sensitive PCR assay. Despite gene proximity, typical PML-RARA transcripts were only rarely detected in irradiated cells. The same phenomenon was observed at similar frequency in control non-irradiated cells. These findings made us investigate whether such transcripts could also be detected in peripheral blood cells from normal individuals. PML-RARA transcripts were observed at low frequencies in isolated lymphoid and granulocytic cell populations, with similar incidence in both cell types. The data thus indicate that the PML and RARA genes are not particularly susceptible to the clastogenic effects of gamma-irradiation, and that, similar to what has been reported for other chromosomal translocations, transcriptionally active PML-RARA rearrangements can be generated in normal hematopoietic cells of different lineages without apparent oncogenic consequences.
authors.affiliation: Institute of Histology and Embryology, Lisbon Medical School, Lisbon, Portugal.
authors.forename: A S
authors.initials: AS
authors.lastname: Quina
authors.forename: P
authors.initials: P
authors.lastname: Gameiro
authors.forename: M
authors.initials: M
authors.lastname: Sá da Costa
authors.forename: M
authors.initials: M
authors.lastname: Telhada
authors.forename: L
authors.initials: L
authors.lastname: Parreira
mesh_terms: D002869:Chromosome Aberrations / Q000209:etiology; D025063:Chromosome Disorders; D005720:Gamma Rays / Q000009:adverse effects; D006412:Hematopoietic Stem Cells / Q000378:metabolism* / Q000528:radiation effects; D006801:Humans; D015473:Leukemia, Promyelocytic, Acute / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D009363:Neoplasm Proteins / Q000235:genetics* / Q000528:radiation effects*; D009687:Nuclear Proteins; D015514:Oncogene Proteins, Fusion / Q000235:genetics* / Q000528:radiation effects*; D000071156:Promyelocytic Leukemia Protein; D018168:Receptors, Retinoic Acid / Q000235:genetics* / Q000528:radiation effects*; D011995:Recombination, Genetic / Q000528:radiation effects; D000072482:Retinoic Acid Receptor alpha; D014157:Transcription Factors / Q000235:genetics* / Q000528:radiation effects*; D014407:Tumor Cells, Cultured / Q000378:metabolism / Q000528:radiation effects; D025521:Tumor Suppressor Proteins
chemical_list: D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D015514:Oncogene Proteins, Fusion; D000071156:Promyelocytic Leukemia Protein; C000607071:RARA protein, human; D018168:Receptors, Retinoic Acid; D000072482:Retinoic Acid Receptor alpha; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; C093476:promyelocytic leukemia-retinoic acid receptor alpha fusion oncoprotein; C070576:PML protein, human