Impact of Patient-Derived Acellular Ascites on Drug Responses in Ovarian Cancer Cell Lines Through Activation of Key Signaling Pathways

Background

Ovarian cancer is one of the deadliest gynecological malignancies, with a 5-year survival rate of only 30% for patients with advanced epithelial ovarian cancer (EOC). Although surgery and chemotherapy (e.g., carboplatin and paclitaxel) are standard treatments, many patients eventually develop chemoresistance, leading to treatment failure. Malignant ascites, a common complication in advanced ovarian cancer patients, not only provides a unique microenvironment for tumor cells but may also induce chemoresistance through signaling molecules. However, the specific mechanisms by which ascites affects drug responses in ovarian cancer cells remain incompletely understood. Therefore, studying how ascites influences drug responses by activating intracellular signaling pathways is crucial for developing more effective personalized treatment strategies.

Source of the Paper

This study was conducted by Katharina Bischof, Andrea Cremaschi, and other researchers from the Department of Cancer Immunology at the University of Oslo, Norway, in collaboration with institutions such as the National University of Singapore and Tampere University in Finland. The paper was published online on September 8, 2024, in the journal Molecular Oncology (DOI: 10.¹⁰⁰²⁄₁₈₇₈-0261.13726).

Research Process and Results

1. Study Design and Sample Preparation

The research team collected ascites samples from 20 treatment-naïve ovarian cancer patients and prepared acellular ascites fluid (AAF) through filtration and centrifugation. These AAF samples were used to culture five ovarian cancer cell lines (OVCAR3, OVCAR5, OVCAR8, SKOV3, and NCI/ADR-RES) to investigate their impact on drug responses.

2. Drug Sensitivity Testing

The researchers first tested the cytotoxicity of standard therapeutic drugs (e.g., paclitaxel and carboplatin) under different AAF conditions. Through high-throughput drug screening, they found that the addition of AAF significantly reduced cell sensitivity to standard therapeutic drugs. For example, certain AAF samples (e.g., A19) almost completely induced resistance to paclitaxel and carboplatin. Additionally, the study revealed that AAF activated key signaling pathways such as STAT3, PI3K/AKT, and MAPK/ERK, which are closely associated with chemoresistance.

3. Signaling Pathway Analysis

To further investigate how AAF influences drug responses through signaling pathways, the research team used phospho flow cytometry to analyze signaling changes in cells stimulated with AAF. The results showed that AAF significantly increased the phosphorylation levels of signaling molecules such as STAT3, STAT5, AKT, and NF-κB. In particular, STAT3 activation was closely related to the IL-6 signaling pathway, and antibodies targeting the IL-6 receptor (IL6R) effectively inhibited STAT3 phosphorylation.

4. Screening of Novel Drugs

To overcome AAF-induced chemoresistance, the research team also tested the efficacy of several FDA-approved novel drugs (e.g., trametinib, fludarabine, and rapamycin). The results demonstrated that these drugs effectively inhibited cell growth under certain conditions, especially when combined with standard therapeutic drugs, showing synergistic effects. For example, trametinib and fludarabine exhibited high efficacy in multiple conditions.

5. Evaluation of Combination Therapies

The research team further evaluated the therapeutic effects of combining standard therapeutic drugs with novel drugs. By calculating the Drug Sensitivity Score (DSS) and Combination Ratio (CR), they found that certain combinations (e.g., carboplatin with rapamycin) showed significant advantages in overcoming AAF-induced resistance. Additionally, the study used the Zero-Interaction Potency (ZIP) model to assess drug synergy, revealing that combinations of rapamycin and fludarabine with carboplatin or paclitaxel exhibited significant synergistic effects under various conditions.

Conclusions and Significance

This study reveals that patient-derived acellular ascites induces chemoresistance in ovarian cancer cells by activating key signaling pathways such as STAT3, PI3K/AKT, and MAPK/ERK. The research also demonstrates the potential of novel drugs (e.g., trametinib and fludarabine) in overcoming this resistance. These findings provide important theoretical foundations for developing personalized treatment strategies based on the molecular characteristics of ascites.

Research Highlights

1. Innovative Methodology: The study systematically analyzed the impact of ascites on drug responses in ovarian cancer cells for the first time and revealed the activation mechanisms of key signaling pathways through phospho flow cytometry.
2. Clinical Application Potential: The study proposes strategies to overcome chemoresistance by blocking the IL-6 signaling pathway or using novel drug combinations, offering new insights for precision medicine in ovarian cancer.
3. Rich Data Resources: The research team accumulated over 10,000 data points through high-throughput drug screening and signaling pathway analysis, providing valuable resources for future studies.

Additional Valuable Information

The study also found that certain ascites samples (e.g., A19) have a strong ability to induce resistance, which may be related to the molecular characteristics of the patient’s tumor. Future research could further explore the roles of other signaling molecules (e.g., cytokines and growth factors) in ascites to comprehensively understand their impact on the tumor microenvironment.

This study not only deepens our understanding of the mechanisms of chemoresistance in ovarian cancer but also provides important experimental evidence for developing more effective treatment strategies.