Abstract B40: High-throughput screening of new potential targets for high-grade serous ovarian cancer treatment

Abstract

Abstract High-grade serous ovarian cancer (HGSOC) is the most common cause of gynecologic-cancer-associated death. Although HGSOC is initially extremely sensitive to platinum-based chemotherapy, relapse and progression to chemotherapy resistance are frequently seen, resulting in the low 5-year survival rate of this disease. Therefore, we aim to establish a feasible methodology that combines genome editing and single-cell RNA-seq to high-throughput screen new potential targets that could be utilized alone or combined with platinum for HGSOC treatment. Firstly, we constructed several inducible Cas9-expressed HGSOC cell lines, including both platinum-sensitive and -resistant cells. Secondly, we transduced these cell lines with a pooled sgRNA lentivirus consisting of 105 non-target scrambled sgRNAs and sgRNAs against 188 genes (10 sgRNAs per gene) that are currently targets of FDA/EMA approved drugs or drugs undergoing clinical trials in ovarian cancer treatment. Our analysis of multiple HGSOC dissociated tumors by single-cell RNA-seq has revealed intertumoral heterogeneity in expression of these drug targets in vivo. The majority of these 188 genes, approximately two thirds, are expressed in low level in most epithelial ovarian cancer (EOC) cells. Only 4 genes (AKT1, IL6, C1QA, INHBA) show relatively high expression, and only in a small subset of EOC cells. Also, the remaining drug target genes that are expressed show intertumoral heterogeneity, e.g., high expression of PARP-1 in tumors that are potentially deficient in homologous recombination repair. To elucidate the functionality of these drug targets, we will next analyze the transcriptomic effects of specific gene CRISPR/Cas9 knockouts in these HGSOC cell lines by droplet-based single-cell RNA-seq. From the data, we will compare the differences between platinum-sensitive and -resistant cell lines after the gene knockouts to identify the correlations between specific genetic perturbations and platinum resistance. As a future perspective, we will continue optimizing our platform for screening other potential targets. Overall, this study provides a comprehensive and unbiased approach for potential HGSOC target screening. Note: This abstract was not presented at the conference. Citation Format: Jun Dai, Erdogan Pekcan Erkan, Kaiyang Zhang, Katja Kaipio, Tarja Lamminen, Kaisa Huhtinen, Johanna Hynninen, Seija Grenman, Olli Mikael Carpen, Sampsa Hautaniemi, Anna Vähärautio. High-throughput screening of new potential targets for high-grade serous ovarian cancer treatment. [abstract]. In: Proceedings of the AACR Conference: Addressing Critical Questions in Ovarian Cancer Research and Treatment; Oct 1-4, 2017; Pittsburgh, PA. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(15_Suppl):Abstract nr B40.