Aneurysmal bone cysts (ABC) are locally aggressive bone tumors that often feature chromosome 17p13 rearrangements. One of the ABC 17p13 rearrangementst(16;17)(q22;p13) -was recently shown to create a CDH11-USP6 fusion in which the USP6/TRE17 oncogene is overexpressed through juxtaposition with the CDH11 promoter. Herein, we characterize four different ABC translocations involving 17p13, and we show that each is associated with a novel USP6 fusion oncogene. Specifically, we demonstrate that t(1;17), t(3;17), t(9;17), and t(17;17) result in USP6 fusions with TRAP150 (thyroid receptor-associated protein 150), ZNF9 (ZiNc Finger 9), Osteomodulin, and COL1A1 (Collagen 1A1), respectively. The oncogenic mechanism in these fusion genes is akin to CDH11-USP6, with the USP6 coding sequences juxtaposed to the promoter regions in each of the four novel translocation partners. The novel fusion partners appear well suited to drive USP6 transcription in the bone/ mesenchymal context: osteomodulin is expressed strongly in osteoblastic lineages, and the COL1A1 promoter has an oncogenic role in the mesenchymal cancer dermatofibrosarcoma protuberans. In summary, these studies show that USP6 oncogenic activation results from heterogeneous genomic mechanisms involving USP6 transcriptional upregulation by juxtaposition with ectopic promoters.

Chemotherapy-induced tumor necrosis and surgical margins are important prognostic factors for local control of patients with osteosarcoma.

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This new histopathologic analysis technique for the evaluation of neoadjuvant chemotherapy effectiveness (which does not rely on tumor volume for its assessment) is a valuable prognostic indicator for patients with Ewing's sarcoma treated with surgery. Based on this preliminary report, cases of grade I or II chemotherapeutic tumor response should be considered clinical failures and a different, more aggressive postoperative chemotherapy regimen should be considered.