Purpose: Uterine carcinosarcoma (CS) is a rare aggressive malignancy frequently presenting at advanced stage of disease with extrauterine metastases. Median survival is less than 2 years due to high relapse rates after surgery and poor response to chemotherapy or radiotherapy. The goal of this study was to identify novel therapeutic targets. Experimental Design: We applied RNA-SEQ analysis to prospectively collected uterine CS tumor samples from patients undergoing primary surgical resection and for comparison, normal endometrial tissues from postmenopausal women undergoing hysterectomy for benign indications. Functional assays were done in primary CS cell lines developed from patients and in established cell lines, as well as a cell-line derived xenograft model. Validation was done by analysis of an independent cohort of uterine CS patients from The Cancer Genome Atlas (TCGA). Results: Rac GTPase activating protein 1 (RACGAP1) was identified to be highly upregulated in uterine CS. Functional assays showed that RACGAP1 mediates motility and invasion via regulation of STAT3 phosphorylation and survivin expression. RACGAP1 depletion or survivin inhibition abrogated motility and invasiveness of CS cells, while RACGAP1 overexpression conferred invasiveness to endometrial adenocarcinoma cells. In the TCGA cohort, RACGAP1 expression correlated with survivin expression and extrauterine spread of disease. Conclusions: The RACGAP1-STAT3-survivin signaling pathway is required for the invasive phenotype of uterine CS and is a newly identified therapeutic target in this lethal disease.
- Received August 29, 2015.
- Revision received March 9, 2016.
- Accepted April 4, 2016.
- Copyright ©2016, American Association for Cancer Research.