Molecular characterization of carcinosarcomas arising in the uterus and ovaries.

Gynaecological carcinosarcomas are rare biphasic tumours which are highly aggressive. We performed molecular investigations on a series of such tumours arising in the uterus (n = 16) and ovaries (n = 10) to gain more information on their mutational landscapes and the expression status of the genes HMGA1/2, FHIT, LIN28A, and MTA1, the pseudogenes HMGA1P6 and HMGA1P7, and the miRNAs known to influence expression of the above-mentioned genes. In uterine carcinosarcomas (UCS), we identified mutations in KRAS, PIK3CA, and TP53 with a frequency of 6%, 31%, and 75%, respectively, whereas in ovarian carcinosarcomas (OCS), TP53 was the only mutated gene found (30%). An inverse correlation was observed between overexpression of HMGA1/2, LIN28A, and MTA1 and downregulation of miRNAs such as let-7a, let-7d, miR26a, miR16, miR214, and miR30c in both UCS and OCS. HMGA2 was expressed in its full length in 14 UCS and 9 OCS; in the remaining tumours, it was expressed in its truncated form. Because FHIT was normally expressed while miR30c was downregulated, not both downregulated as is the case in several other carcinomas, alterations of the epithelial-mesenchymal transition through an as yet unknown mechanism seems to be a feature of carcinosarcomas.

Novel GTF2I-PDGFRB and IKZF1-TYW1 fusions in pediatric leukemia with normal karyotype.

BACKGROUND: Many cases of acute lymphoblastic leukemia (ALL) carry visible acquired chromosomal changes of pathogenetic, diagnostic, and prognostic importance. Nevertheless, from one-fourth to half of newly diagnosed ALL patients have no visible chromosomal changes detectable by G-banding analysis at diagnosis. The introduction of powerful molecular methodologies has shown that many karyotypically normal ALLs carry clinically important submicroscopic aberrations. CASE PRESENTATION: We used fluorescence in situ hybridization (FISH), array comparative genomic hybridization (aCGH), RNA sequencing, reverse transcription (RT) and genomic polymerase chain reaction (PCR), as well as Sanger sequencing to investigate a case of pediatric ALL with a normal karyotype. FISH with a commercial PDGFRB breakapart probe showed loss of the distal part of the probe suggesting a breakpoint within the PDGFRB locus. aCGH revealed submicroscopic deletions in chromosome bands 5q32q35.3 (about 30 Mb long, starting within PDGFRB and finishing in the CANX locus), 7q34 (within TCRB), 9p13 (PAX5), 10q26.13 (DMBT1), 14q11.2 (TRAC), and 14q32.33 (within the IGH locus). RNA sequencing detected an in-frame GTF2I-PDGFRB and an out-of-frame IKZF1-TYW1 fusion transcript. Both fusion transcripts were verified by RT-PCR together with Sanger sequencing and interphase FISH. The GTF2I-PDGFRB fusion was also verified by genomic PCR and FISH. The corresponding GTF2I-PDGFRB fusion protein would consist of almost the entire GTF2I and that part of PDGFRB which harbors the catalytic domain of the tyrosine kinase. It would therefore seem to lead to abnormal tyrosine kinase activity in a manner similar to what has been seen for other PDGFRB fusion proteins. CONCLUSIONS: The examined pediatric leukemia is a Ph-like ALL which carries novel GTF2I-PDGFRB and IKZF1-TYW1 fusion genes together with additional submicroscopic deletions. Because hematologic neoplasms with PDGFRB-fusion genes can be treated with tyrosine kinase inhibitors, the detection of such novel fusions may be clinically important. Since the GTF2I-PDGFRB could be detected only after molecular studies of the leukemic cells, further investigations of ALL-cases, perhaps especially but not exclusively with a normal karyotype, are needed in order to determine the frequency of GTF2I-PDGFRB in leukemia, and also to find out which clinical impact the fusion may have.

Pyrosequencing Analysis of MGMT Promoter Methylation in Meningioma.

BACKGROUND: Methylation of the O6-methylguanine-DNA methyltransferase (MGMT) gene promoter is a well-established predictor of response to the DNA-alkylating agent temozolomide in patients with glioblastoma. MATERIALS AND METHODS: Pyrosequencing analysis was used to determine the MGMT promoter methylation status in 61 meningiomas, to clarify whether it might have a predictive role. RESULTS: Only two tumors (3%) had a mean methylation frequency higher than the cut-off value of 10% for the four CpG sites examined. CONCLUSION: The methylation of the MGMT promoter is uncommon, or occurs at a low frequency in meningiomas. There is no convincing rationale to test such tumors for their MGMT methylation status in a clinical setting.