14-3-3 fusion oncogenes in high-grade endometrial stromal sarcoma.

Cheng-Han Lee, Wen-Bin Ou, Adrian Mariño-Enriquez, Meijun Zhu, Mark Mayeda, Yuexiang Wang, Xiangqian Guo, Alayne L Brunner, Frédéric Amant, Christopher A French, Robert B West, Jessica N McAlpine, C Blake Gilks, Michael B Yaffe, Leah M Prentice, Andrew McPherson, Steven J M Jones, Marco A Marra, Sohrab P Shah, Matt van de Rijn, David G Huntsman, Paola Dal Cin, Maria Debiec-Rychter, Marisa R Nucci, Jonathan A Fletcher, Proceedings of the National Academy of Sciences of the United States of America 109, 929-34 (2012) 2012
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14-3-3 proteins are ubiquitously expressed regulators of various cellular functions, including proliferation, metabolism, and differentiation, and altered 14-3-3 expression is associated with development and progression of cancer. We report a transforming 14-3-3 oncoprotein, which we identified through conventional cytogenetics and whole-transcriptome sequencing analysis as a highly recurrent genetic mechanism in a clinically aggressive form of uterine sarcoma: high-grade endometrial stromal sarcoma (ESS). The 14-3-3 oncoprotein results from a t(10;17) genomic rearrangement, leading to fusion between 14-3-3ε (YWHAE) and either of two nearly identical FAM22 family members (FAM22A or FAM22B). Expression of YWHAE-FAM22 fusion oncoproteins was demonstrated by immunoblot in t(10;17)-bearing frozen tumor and cell line samples. YWHAE-FAM22 fusion gene knockdowns were performed with shRNAs and siRNAs targeting various FAM22A exons in an t(10;17)-bearing ESS cell line (ESS1): Fusion protein expression was inhibited, with corresponding reduction in cell growth and migration. YWHAE-FAM22 maintains a structurally and functionally intact 14-3-3ε (YWHAE) protein-binding domain, which is directed to the nucleus by a FAM22 nuclear localization sequence. In contrast to classic ESS, harboring JAZF1 genetic fusions, YWHAE-FAM22 ESS display high-grade histologic features, a distinct gene-expression profile, and a more aggressive clinical course. Fluorescence in situ hybridization analysis demonstrated absolute specificity of YWHAE-FAM22A/B genetic rearrangement for high-grade ESS, with no fusions detected in other uterine and nonuterine mesenchymal tumors (55 tumor types, n = 827). These discoveries reveal diagnostically and therapeutically relevant models for characterizing aberrant 14-3-3 oncogenic functions.