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Ding, Yuchen

University of British Columbia

Clear Cell Ovarian Cancer (CCOC) is a chemoresistant subtype of ovarian cancer, accounting for ~10% of epithelial ovarian carcinomas (EOC) in North America and up to 30% in Japan. Unlike in the more common high-grade serous ovarian cancers, hematogenous spread and extraperitoneal metastasis are prevalent in CCOC but have been understudied due to a lack of suitable models. High expression of Cystathionine Gamma-Lyase (CTH) and mutations in AT-Rich Interactive Domain-Containing Protein 1A (ARID1A) are common in CCOC. CTH, a key enzyme in the transsulfuration pathway, is a marker for CCOC. Inactivating CTH reduces CCOC’s metastatic potential and improves chemotherapy responsiveness. Loss of ARID1A occurs in ~65% of CCOC cases, inducing ROS accumulation and reliance on oxidative phosphorylation (OXPHOS) for energy. EO3001, a synthetic drug, selectively transports extracellular Cu (II) to mitochondria, inducing ROS and triggering cuproptosis. ARID1A-deficient cells show increased sensitivity to EO3001. To investigate the effectiveness of EO3001 and CTH inhibitors in CCOC, we used the Pulmonary Metastasis Assay (PuMA). This model enables metastases to be seeded via tail vein injections and studied either immediately or after full establishment, providing a more complex microenvironment than traditional 2D/3D models. We generated isogenic CCOC cell lines (-/+ CTH loss & -/+ ARID1A loss) using CRISPR-Cas9. EO3001 was obtained through collaboration, while a CTH inhibitor library was screened by our collaborators; 3 candidates showed promising effects and were further tested. We evaluated EO3001's therapeutic impact on tumorigenic potential and cell growth in vitro and ex vivo. Both early- and late-harvest PuMA were optimized to assess CTH inhibitors and EO3001. In both assays, all 3 CTH inhibitors showed significant inhibitory effects on CCOC, offering a novel therapeutic strategy not only for CCOC but also other cancers expressing CTH. Differences in EO3001 response were noted between CCOC -/+ ARID1A cell lines, with hypoxia reducing EO3001's effects, likely due to changes in glycolysis and OXPHOS. Exploiting OXPHOS dependence in ARID1A-deficient CCOC, EO3001 could be a promising therapeutic approach. These findings highlight the PuMA assay’s potential for testing novel treatments for metastatic CCOC.

Text; Still Image

2025-02-24

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/90417

Pathology and Laboratory Medicine

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/