ABSTRACT
Genomic amplification of c-Jun and its upstream kinases have been implicated as a mechanism of progression from well-differentiated to dedifferentiated liposarcoma. To further define the role of c-Jun in liposarcoma progression, we performed immunohistochemistry for c-Jun and its activating kinase ASK1 on a series of liposarcomas (n = 81). We correlated the results with fluorescence in situ hybridization to detect c-Jun amplification. We also derived new cell lines from dedifferentiated liposarcomas with c-Jun amplification. c-Jun protein is expressed in the majority of dedifferentiated liposarcomas (91%) and their well-differentiated components (59%), but only in the minority of pure well-differentiated liposarcomas (27%). When c-Jun is amplified in dedifferentiated liposarcoma, it is interspersed with amplified MDM2 on ring and giant marker chromosomes. MDM2 amplification is one of the earliest events in liposarcoma development, and these results suggest that c-Jun was amplified at a similar time in the evolution of the tumour. In addition, shRNA to c-Jun in c-Jun-amplified liposarcoma cells reduces cell number in vitro and inhibits tumour formation in vivo without an observable effect on the differentiation state of the liposarcoma cells. Thus, c-Jun amplification is oncogenic in liposarcomas but not always sufficient for inhibition of adipocytic differentiation.
Subject(s)
Adipocytes/pathology , Liposarcoma/metabolism , Proto-Oncogene Proteins c-jun/metabolism , Animals , Cell Differentiation/physiology , Cell Line, Tumor , Disease Progression , Gene Amplification , Genes, jun , Humans , In Situ Hybridization, Fluorescence , Liposarcoma/genetics , Liposarcoma/pathology , MAP Kinase Kinase Kinase 5/metabolism , Mice , Mice, NudeABSTRACT
BACKGROUND: Preimplantation genetic diagnosis (PGD) by fluorescence in situ hybridization (FISH) is being employed increasingly by medical centers and private companies. Validation of any clinical assay, particularly one with novel applications such as PGD by FISH, is of critical importance in the clinical setting. This importance is recognized by both the College of American Pathologists (CAP) and the American College of Medical Genetics (ACMG), who recommend validation of FISH assays in the clinical setting. Validation of FISH assays for PGD is especially significant, as only one or two cells (blastomeres) will be available for testing of a given embryo. METHODS: We have developed validation protocols for a variety of FISH assays, including sex identification, structural chromosomal aneusomy, and aneuploidy screening with the Vysis, Inc., PGT probe panel. RESULTS: Our validation results show good individual performance of commercially available probes, and decreasing overall efficiency as the number of probes included in an assay increases.
