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

Abstract

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.

Frequent expression of KIT in endometrial stromal sarcoma with YWHAE genetic rearrangement

“…[1][2][3] Histologically, YWHAE-NUTM2A/B endometrial stromal sarcomas are characterized by round to epithelioid cells with scant to moderate faintly eosinophilic cytoplasm and high-grade cytologic features. The nuclei are larger in size and more irregular in contour compared with the tumor nuclei from classic lowgrade endometrial stromal sarcoma and mitoses are readily identified (410 mitoses per 10 high power fields).…”

YWHAE rearrangement identified by FISH and RT-PCR in endometrial stromal sarcomas: genetic and pathological correlations

“…Recently, Lee et al 8 identified the genes rearranged in the t(10;17)(q22;p13) translocation previously described in endometrial stromal sarcoma [9][10][11] and also in pediatric clear cell sarcoma of the kidney, 12,13 corresponding to an inframe YWHAE-FAM22 fusion of YWHAE exons 5-2 of FAM22A or FAM22B. 8 The goal of the present study was to analyze the rearrangement of the YWHAE gene by FISH break-apart and RT-PCR techniques, and to identify correlations between YWHAE gene status and morphology, immunohistochemistry (IHC), and clinical behavior in a series of high-grade-morphology endometrial stromal sarcomas with no JAZF1 rearrangements. Given the lack of published data about YWHAE FISH break-apart, 8 we also aimed to identify the optimal threshold for positivity in RT-PCR for cell rearrangements.…”

“…8 The goal of the present study was to analyze the rearrangement of the YWHAE gene by FISH break-apart and RT-PCR techniques, and to identify correlations between YWHAE gene status and morphology, immunohistochemistry (IHC), and clinical behavior in a series of high-grade-morphology endometrial stromal sarcomas with no JAZF1 rearrangements. Given the lack of published data about YWHAE FISH break-apart, 8 we also aimed to identify the optimal threshold for positivity in RT-PCR for cell rearrangements.…”

RNA‐sequencing identifies novel GREB1‐NCOA2 fusion gene in a uterine sarcoma with the chromosomal translocation t(2;8)(p25;q13)

“…The use in recent years of next generation sequencing (NGS) methodology has played an important role in identifying such molecular rearrangements. By way of example, NGS identified a YWHAE‐NUTM 2 fusion brought about by a 10;17‐translocation and a ZC3H7B‐BCOR caused by an X;22‐translocation in ESS, thus adding two new pathogenetic subgroups to this spectrum of tumors 6, 7…”