Ovarian cancer is the most deadly cancer of the female reproductive system. Due to its hidden location, extremely diverse tumor types, and lack of effective screening for early detection, it is often diagnosed only in advanced stages. The most common and aggressive form is high-grade serous ovarian cancer (HGSOC). Standard therapy involves treatment with platinum-based drugs such as carboplatin, but the effectiveness of treatment is greatly limited by the development of chemoresistance. Recent studies have therefore focused on identifying new biomarkers that could be used to predict cell resistance to treatment. ATP7B copper transporters have great potential, as they are capable of reducing intracellular platinum concentrations by pumping molecules into vesicular structures. In addition to efforts to improve the prediction of chemoresistance, scientists are working to identify new agents that would increase the cytotoxicity of carboplatin and thus the effectiveness of treatment for resistant forms of tumors. A promising compound in this area is brefeldin A, a fungal metabolite that causes the breakdown of the Golgi apparatus and disrupts vesicular transport. So far, the reagent has only been tested on a limited set of ovarian cancer cell lines that did not include cells with HGSOC histology and did not focus on the effect of brefeldin A on carboplatin cytotoxicity and ATP7B expression. In the future, it would be necessary to conduct more experiments to achieve higher accuracy of results, optimize the concentration of brefeldin A, and investigate its mechanism of action through which it affects the reduced expression of ATP7B in the OAW28 cell line.
In this work, we aimed to examine the effect of carboplatin on the PEO1 and OAW28 cell lines, which are cell lines with HGSOC histology. The PEO1 cell line was isolated from a platinum-sensitive patient, while OAW28 originated from a chemoresistant one. Due to the lack of protocols, we optimized conditions using the alamarBlue reagent and found that carboplatin effectiveness in both cell lines is strongly dose-dependent. In OAW28, we observed hormesis - low carboplatin concentrations promoted growth, while higher concentrations inhibited it and reduced viability. PEO1 proved more sensitive to platinum treatment than OAW28. We also tested the effect of brefeldin A on carboplatin cytotoxicity but detected no synergism, as the main issue was the intrinsic cytotoxicity of brefeldin A at high concentrations. Using flow cytometry, we were the first to demonstrate ATP7B expression in both cell lines, with no difference in expression levels. However, brefeldin A significantly reduced ATP7B expression in OAW28 but not in PEO1. Future experiments should confirm these results, optimize brefeldin A concentration, and further investigate its mechanism in reducing ATP7B expression in OAW28.
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