Establishment of Stable Knockdown of MACC1 Oncogene in Patient-Derived Ovarian Cancer Organoids.

High-grade serous ovarian cancer (HGSOC) remains the most lethal gynecological malignancy, and there is still an unmet medical need to deepen basic research on its origins and mechanisms of progression. Patient-derived organoids of high-grade serous ovarian cancer (HGSOC-PDO) are a powerful model to study the complexity of ovarian cancer as they maintain, in vitro, the mutational profile and cellular architecture of the cancer tissue. Genetic modifications by lentiviral transduction allow novel insights into signaling pathways and the potential identification of biomarkers regarding the evolution of drug resistance. Here, we provide an in-depth and detailed protocol to successfully modify the gene expression of HGSOC-PDOs by lentiviral transduction. As an example, we validate our protocol and create a stable knockdown of the MACC1 oncogene with an efficacy of ≥72% in two HGSOC-PDO lines, which remained stable for >3 months in culture. Moreover, we explain step-by-step the sample preparation for the validation procedures on transcriptional (qPCR) and protein (Western Blot) levels. Sustained downregulation of specific genes by lentiviral transduction enables the analysis of the resulting phenotypic and morphological changes. It serves as a valuable in-vitro model to study the mechanisms of ovarian cancer pathogenesis and allows for the evaluation of therapeutic approaches.