Grant: Travel Awards - Institute Community Support

Introduction: Ovarian cancers are a common and deadly group of diseases. Every year, ovarian cancer will kill over 140,000 people worldwide. Of these, roughly 70% of cases will be people with the most common subtype of ovarian cancer: High Grade Serous Ovarian Cancer (HGSC). The vast majority (96%) of HGSC cases have mutations in the gene TP53 and many also have mutations in members of the homologous recombination repair pathway. This pathway is necessary for effective DNA repair, meaning that its loss can lead to an accumulation of mutations in affected cells. This instability may be an important driver of HGSC initiation, but the effect of mutating these genes in normal human cells has not been tested. Methods: We are genetically engineering human organoids to have dual loss of both TP53 and various homologous recombination repair genes. These organoids will be modified using CRISPR-Cas9 constructs aimed at cutting and disrupting target gene function. Histology, immunofluorescence staining and single-cell DNA sequencing will be used to test for homologous recombination deficiency in the modified organoids. Knockouts that exhibit cancer-like growth will be tested for sensitivity to PARP inhibitors, a targeted clinical therapy. Results: Preliminary data from engineered organoids shows that their mutation leads to genetic instability and abnormal cell structure. Other mutants are currently being validated and their effects on growth will be forthcoming. Implications: This research will investigate early events in HGSC development, potentially identifying key events in cancer initiation. Currently, PARP inhibitors are used as an effective treatment for a specific subset of HGSCs, but their effect on a broader group remains unclear. As a result, this work may also identify a new cohort of patients that may be sensitive to PARP inhibitors, thereby expanding the pool of patients that can be treated with this targeted therapy.