Abstract 1455: Impact of ZFHX3 loss on endometrial cancer progression

Abstract Endometrial cancer (EC) is the sixth most common cancer among women and ranks as the leading type of gynecological cancer. Although EC is often diagnosed early, current treatment plans significantly limit fertility-sparing options, posing challenges for younger patients. This research focuses on the role of the gene ZFHX3 (ATBF1) to understand its effects on the advancement of endometrial cancer. In order to investigate this, we first transfected 12Z-ESR1 epithelial endometrial cells with ZFHX3 siRNA to create transient gene knockdowns. Following cell collection, western blotting was performed to measure ZFHX3 protein expression levels. Furthermore, we used CRISPR Cas9 plasmid guides tagged with GFP to establish more stable knockdowns. After bacterial transformation, we utilized flow cytometry to sort GFP-expressing cells and confirm successful gene editing. Subsequent western blots were conducted to validate which guide were successful in creating an efficient knockdown of ZFHX3. In vivo studies complemented these cellular experiments. We dissected the uteri of mice with ZFHX3 homozygous and ZFHX3/Pten heterozygous knockdowns. Analysis through H&E staining allowed us to quantify the number of endometrial glands. Our findings revealed that ZFHX3 loss disrupts progesterone signaling, a critical regulator of endometrial function, and leads to increased cell proliferation, which may drive tumor growth. These results highlight ZFHX3 as a potential target for therapeutic strategies aimed at balancing fertility preservation and inhibiting the progression of cancer. Citation Format: Areebah Qazi, Sophia Agrusa, Swornalata Pukhrambam, Juveria Ali, Sanjeev Ganesh, Jessica Back, Mike R. Wilson. Impact of ZFHX3 loss on endometrial cancer progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 1455.