Developing new ovarian cancer therapies – lessons from a novel genetically engineered mouse model
2The clinical research institute at Rambam (CRIR), Rambam Health Care Campus, Haifa, Israel
3Pre Clinical Research Authority, Technion – Israel Institute of Technology, Haifa, Israel
4Hebrew University, Jerusalem, Israel
5Department of Pathology, Bnai Zion Medical center, Haifa, Israel
6Department of Pathology, Ziv Medical Center, Safed, Israel
7Department of Pathology, Rambam Health Care Campus, Haifa, Israel
8Department of Oncology, Rambam Health Care Campus, Haifa, Israel
Introduction: Ovarian carcinosarcoma (OCS) is a rare and highly lethal subtype of ovarian cancer, with an admixture of epithelial (carcinoma) and mesenchymal (sarcoma) components. Limited knowledge of its pathogenesis and a lack of effective treatments highlight the need for preclinical models to study this disease.
In this study we test the effect of non-steroidal anti-inflammatory drugs (NSAIDs), for the treatment and prevention of OCS, using a newly designed genetically engineered mouse model (GEMM).
Materials and Methods: We created a novel OCS GEMM, by knocking out OCS relevant tumor suppressor genes, namely Trp53, Brca2 and Pten, in the ovarian surface epithelium and fallopian tube epithelium. The resulting tumors replicated OCS`s dual morphology and expressed OCS markers such as Vimentin, Cytokeratin, Estrogen Receptor and WT-1. Mice were engineered to express a red fluorescent marker in tumor cells for convenient tumor imaging and tracing, and cell lines were generated from these tumors. To test the role of NSAIDs, mice were treated with Indomethacin and tumor size, metastasis and survival were assessed and compared with untreated mice. In order to characterize the effects of indomethacin, we performed single-cell RNA sequencing (scRNA-seq) analysis of tumors and metastasis and validates the results using IHC and flow cytometry.
Results and discussion: Indomethacin treated mice had significantly smaller primary tumors and longer survival, but a markedly higher metastasis rate, reflecting a double-edged role for inflammation in OCS. scRNA-seq analysis revealed that Indomethacin affects the tumor micro-environment (TME) and cancer cells. Indomethacin treated cancer cells expressed lower levels of angiogenesis and ECM turnover related genes, leading to a reduction of angiogenesis and ECM deposits, resulting in smaller primary tumors. The most pronounced effect of indomethacin on the TME was a reduction in the number of macrophages in the primary tumors. The selective pressure in the primary tumor resulted in escape of highly aggressive that overcame the indomethacin suppressive effect on the premetastatic niche.
Conclusions: We have developed a reproducible model of OCS that accurately mirrors the human disease. We used this model to study the complex role of NSAIDs in OCS.