Novel models of myxoid liposarcoma xenografts mimicking the biological and pharmacologic features of human tumors.

PURPOSE: Myxoid liposarcoma is a common subtype of liposarcoma. It is associated in more than 90% of cases with the chromosomal translocation t(12;16)(q13;p11) leading to the fusion FUS-CHOP gene that is responsible for the oncogenic transformation of preadipocytes. Recently the marine natural product trabectedin has shown highly selective activity for myxoid liposarcoma, even in the most aggressive round-cell subtype. EXPERIMENTAL DESIGN: Fragments of 17 sarcomas were transplanted s.c. in female athymic NCr-nu/nu mice. Xenografts were established and characterized by morphology, fluorescence in situ hybridization analysis for the translocation and reverse transcriptase-PCR analysis for fusion transcripts. Trabectedin was injected i.v. RESULTS: Seven of 17 tumors grew as continuous xenografts, five of them being myxoid liposarcoma of the round-cell subtype. The chromosomal rearrangement and fusion transcripts in different passages were the same as in the human tumors from which they were derived. The responsiveness to trabectedin in type II myxoid liposarcoma xenografts was as high as in patients. The pathologic response was associated with the presence of the FUS-CHOP fusion gene, indicating that the drug does not totally eradicate the disease. Type III myxoid liposarcoma xenografts seemed much less sensitive to trabectedin, confirming previous clinical observations. CONCLUSIONS: This study reports for the first time the characterization of human myxoid liposarcoma xenografts that adequately mimic the biological and pharmacologic features of the human tumor. These models offer a useful tool for investigating the mechanism of selectivity of trabectedin, testing new combinations with this drug and evaluating novel therapies for myxoid liposarcoma.

Validation of a large Italian Database of 15 STR loci.

Results from a collaborative exercise with proficiency testing conducted by 20 Italian laboratories on the 15 loci included in the Identifiler kit were analyzed by allele sharing methods and by standard population genetics tests. The validated database, including about 1500 subjects, was merged with that of a previous exercise conducted on nine loci, and the resulting allele frequencies, subdivided by Italian region, were published on-line.

Allele sharing in first-degree and unrelated pairs of individuals in the Ge F I AmpFlSTR Profiler Plus database.

Eleven Italian forensic laboratories participated in a population study based on the AB Profiler Plus loci with proficiency testing. The validated database, including 1340 individuals, is available on-line. Tests for Hardy-Weinberg equilibrium, gametic unbalance, and heterogeneity of gene frequency were generally not significant. Gene frequencies at each locus were consistent with those of two previously published Italian studies, but different from a third. Individuals of each subsample were paired, and the total number of alleles shared across the nine loci was determined in each pair. The analysis was replicated over the total sample. In addition, two samples of mother-child pairs (N=315) and full-sib pairs (N=91) were subjected to allele sharing analysis. The resulting distributions were sufficiently distinct from the sample of unrelated pairs as to be of practical usefulness.