Liposarcomas are a heterogeneous group of
sarcomas, including well-differentiated and
dedifferentiated liposarcoma, myxoid/
round cell liposarcoma, and
pleomorphic liposarcoma. Complete surgical resection is the key of treatment.
Radiotherapy, based on the
tumor grade and the vicinity of critical structures with the
tumor, can be used to prevent local recurrence. The group of
dedifferentiated liposarcomas (DDLS) is poorly sensitive to
adjuvant chemotherapy. Improved understanding of the genetic aberrations that lead to
liposarcoma initiation is necessary for the development of targeted
therapies to improve
tumor control and survival. DDLS share genetic abnormalities with other groups, exhibiting high-level amplifications of chromosome 12, including the MDM2 and CDK4 genes, and harbor additional amplifications of chromosomes 6 and 1. Novel
therapies targeted at the gene products of chromosome 12 are currently considered in clinical trials. Our work consisted in a genomic characterization of DDLS to draw up a complete picture of alterations, including genomic signatures,
tumor mutation burden, gene mutations, copy number variations, translocations, gene fusions and methylation modifications. Analysis of translocations helped to understand the mechanisms underlying the amplification processes. Combination of mutations and loss of heterozygosity or homozygous deletions were detected and led to inactivate tumor suppressor genes (TSG). In contrast, methylation anomalies seemed not linked to any particular genomic profile. All identified anomalies, whether amplifications and/or TSG inactivation, involve genes playing a role in p53 regulation, that appears to be the epicenter of the initiation process in DDLS
tumorigenesis, as is also known to be responsible for
Li-Fraumeni syndrome, a family
cancer syndrome highly predisposing to
sarcomas.