Introduction/Background High-grade serous ovarian carcinoma (HGSOC) is a major cause of gynecological mortality and is characterized by an unusual transcoelomic spread, that involves disruption of ovarian tumor capsules and the accumulation of ascites. Epithelial-to-mesenchymal transition (EMT) is a key process that transforms epithelial cells into mesenchymal ones, that express EMT-transcriptional factors (EMT-TFs), such as SNAI1, SNAI2, VIMENTIN or TWIST.

This study aims to investigate the complex interplay between EMT and treatment resistance in HGSOC.

Methodology Ascites (n=9) and tumor tissue (n=9) were collected under sterile conditions from consented patients undergoing surgery for HGSOC at Fundeni Clinical Institute. We established HGSOC ascites-derived primary cultures, followed by DOX (doxorubicin) and CPT (cisplatin) treatment. In vitro drug sensitivity was determined by MTT assay and the effect on cell growth was assessed by IC50 calculation. Total RNA was isolated with the TRIzol method and EMT markers were quantified by real-time PCR and immunohistochemistry.

Results We demonstrate that the gene and protein expression of EMT markers were significantly increased in ascites-derived primary cultures compared to tumor tissues. Moreover, treatment with different concentrations of DOX and CPT increases VIMENTIN and TWIST levels (p<0.05). For HGSOC ascites-derived primary cultures, IC50 of drugs equal to or less than their respective median IC50 (DOX = 0.6 µM, CPT = 50 µM) was considered a sensitive culture, while IC50 values greater than the median IC50 values were considered as resistant culture. We found that SNAI2 expression was increased in the CPT-sensitive group (p=0.02 ). Interestingly, this marker is downregulated in the ovarian cancer TCGA cohort compared to the normal-GTEx from the TNMPlot database (p<0.01).

Conclusion Our findings revealed that HGSOC dissemination could be detected through the dynamics of the EMT markers. Studies are currently being conducted to investigate the synergy between the EMT pathways and chemosensitivity, which can lead to improved personalized treatment.

Disclosures This work was supported by a grant of the Romanian Ministry of Research and Innovation, CCDI-UEFISCDI, project number PN-III-P1–1.2-PCCDI2017–0833/’’Multidisciplinary Consortium for Supporting Research Skills in Diagnosing, Treating and Identifying Predictive Factors of Malignant Gynecologic Disorders-ONCOGIN’’, contract no. 68PCCDI/2018.