Abstract 4043: MYB/AKT3 axis is a key driver of ovarian cancer growth and aggressiveness

Ovarian cancer (OC) is the most common and lethal gynecologic malignancy in the United States, primarily due to late-stage diagnosis and limited treatment options for the advanced disease. It disproportionately affects Black women at every stage, from initial diagnosis to treatment, resulting in higher mortality rates compared to non-Hispanic White women. In an effort to identify novel biomarkers and therapeutic targets for improved clinical management, we discovered MYB as a differentially-expressed gene in OC, exhibiting a race-specific prognostic association. MYB encodes for a transcription factor protein that drives oncogenesis by regulating the expression of a wide array of gene targets. We also found that MYB is expressed in OC cell lines, having elevated levels in aggressive (SKOV3-ip) and chemo-resistant (A2780-Cip) variants compared to their parental counterpart (SKOV3 and A2780) cell lines. Gain- and loss-of-function studies suggested that MYB plays a role in growth, aggressiveness, and chemoresistance. Gene expression profiling of low (SKOV3-Neo) and high (SKOV3-ip-Scr) MYB-expressing cells along with their forced MYB-expressing (SKOV3-MYB) and MYB-silenced (SKOV3-ip-shMYB) derivative lines using the nCounter® PanCancer Progression panel on a nanoString nCounter system, revealed several MYB-driven differentially expressed genes (DEGs). With a 1.5-fold-change cutoff, we identified 164 DEGs in the SKOV3-ip (Scr vs. shMYB) comparison and 87 DEGs in SKOV3 (Neo vs. MYB) comparison. Notably, the majority of DEGs were distinct between these comparisons, suggesting that MYB alters gene expression in a cell-specific manner. Validation of commonly altered genes in additional paired MYB-overexpressing and silenced cell lines by qRT-PCR identified AKT3 as a significant downstream target of MYB. Moreover, KEGG pathway analysis of DEGs in MYB-modulated cells highlighted PI3K pathway as commonly altered. In silico analysis of AKT3 promoter identified seven putative MYB binding regions (P1-P7), and chromatin immunoprecipitation confirmed strong MYB binding to P4 region of the AKT3 promoter. Inhibition of AKT3 through RNA interference resulted in reduced cell proliferation, clonogenicity, migration and invasion, and increased apoptosis in OC cells. These findings suggest that AKT3 serves as a key mediator in driving the oncogenic actions of MYB in ovarian cancer. Citation Format: Kunwar Somesh Vikramdeo, Orlandric Miree, Shashi Anand, Sanjeev Kumar Srivastava, Seema Singh, Rodney P. Rocconi, Ajay Pratap Singh. MYB/AKT3 axis is a key driver of ovarian cancer growth and aggressiveness [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 4043.