Abstract 4698: Gene expression profiling distinguishes between endometrial stromal tumors subtypes

Abstract

Abstract Introduction Endometrial stromal tumors (EST) are the second most prevalent uterine sarcomas. EST are divided into three histosubtypes: benign endometrial stromal nodules (ESN), low-grade endometrial stromal sarcomas (ESS) and the most malignant undifferentiated stromal sarcomas (UES). Moreover, due to clinicopathological features intermediate between classical low-grade ESS and UES, some tumors have been described in the literature as “high-grade ESS”. The histological distinction between these three subtypes has important prognostic implications. The molecular biology of these tumors remains poorly understood because of their low incidence. Patients and Methods In the present study, we performed gene expression profiling of 22 EST using microarray, RNA-Seq and qRT-PCR techniques. Our cohort included 10 classical low-grade ESS (8 with ESS-associated gene fusions), 8 UES and 4 tumors which were classified as high-grade ESS based on the presence of YWHAE-FAM22A/B fusion and histological features. Results Using gene expression microrarrays, we have identified 81 entities differentially expressed in analyzed samples (fold change > 2, p < 0.005). Hierarchical clustering analysis revealed that high-grade ESS formed a separate sub-cluster with a distinct molecular profile as compared with the low-grade ESS and UES cases. Low-grade ESS cases formed 2 distinct sub-clusters, each containing 5 cases, one of which presented gene expression profile partially corresponding to high-grade ESS cases. GO analysis of genes strongly up-regulated in UES specimens showed over-representation of immune response (GO:0006955) and immune system process (GO:0002376) pathways (MARCO, MYO1F, FCN1, GPR183, HLA-DPB1, FCGR2B, NCF1, CCL18, CD28, PTAFR, CCL13, STK4, CD14, NCF4 and CTLA4 genes) (p < 0.05). UES cases were also characterized by significant down-regulation of WT1 tumor suppressor gene as compared to the low- and high-grade ESS. Moreover, both high-grade ESS and UES cases were characterized by significantly lower expression level of PEG3 gene, which has been reported as a tumor suppressor gene. All low-grade ESS cases presented significant over-expression of estrogen receptor ESR1 gene. Microarray results were validated by RNA-Seq and qRT-PCR experiments. Conclusions This study provides gene expression profiles that distinguish between EST subtypes and sheds light on the biology of these tumors. Our results point to immune system involvement in the pathogenesis of UES and support the notion that the current EST classification should discriminate high-grade ESS as a distinct subtype. Citation Format: Joanna Przybyl, Magdalena Kowalewska, Anna Quattrone, Barbara Dewaele, Vanessa Vanspauwen, Julio Finalet-Ferreiro, Michal Swierniak, Elwira Bakula-Zalewska, Janusz A. Siedlecki, Mariusz Bidzinski, Jan Cools, Maria Debiec-Rychter. Gene expression profiling distinguishes between endometrial stromal tumors subtypes. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4698. doi:10.1158/1538-7445.AM2014-4698