Abstract 2657: Impact of STRN4 knockdown on TNBC migration and survival

Abstract Introduction: Striatin 4 (STRN4) is a member of the STRIPAK protein complex, including protein phosphatase 2A (PP2A) and other interacting protein kinases. These proteins interact to play a role in a range of signaling cascades, including MAPK and Hippo signaling. STRN4 has been shown to play a role in several cancer types, as it is a negative prognostic marker of renal, ovarian, and liver cancers. It has also been shown to contribute to liver cancer migration, and its knockdown diminishes pancreatic cell migration and proliferation. However, although STRN4 is associated with a trend of decreased overall survival in breast cancer patients, it is relatively understudied in the context of the disease. Experimental Methods: To better understand the role of STRN4 in breast cancer survival and related processes, an siRNA-mediated knockdown of STRN4 was performed in a patient-derived xenograft-derived triple-negative breast cancer (TNBC) cell line: TU-BcX-4IC (4IC). Using three pre-validated siRNAs (A, B, and C) specific to STRN4 paired with a polymer-based transfection reagent, we knocked down the expression of STRN4. We then monitored the effects of the knockdown on 4IC cell migration and invasion, proliferation, metabolism, and gene expression via Boyden chamber migration assays, colony-forming unit assays, XTT assays, and qRT-PCR, respectively. Results: STRN4 gene expression was significantly diminished 24 hours post-transfection, which was maintained 72 hours post-transfection. However, there was no significant difference in the migration of 4IC cells through a Boyden chamber, and only minor alterations in the expression of epithelial-to-mesenchymal transition markers E-cadherin, Vimentin, CD24, and Jagged1 24, 48 and 72 hours post-knockdown, despite significantly lower expression of STRN4 at these timepoints. However, there was substantially lower colony-forming unit potential and metabolic output in the C siRNA group despite there being no difference between the A and B siRNA groups. Conclusions: Overall, STRN4 knockdown has minimal effects on TNBC cell migration and gene expression 24, 48, and 72 hours after the onset of diminished expression. While this may suggest that STRN4 is not as crucial to TNBC-related processes, much research remains. In the future, we plan to add additional cell lines to the knockdown experimental groups and monitor protein expression during STRN4 knockdown. Citation Format: Caroline Rinderle, Jordan Wright, Olivia Mayer, Bruce Bunnell. Impact of STRN4 knockdown on TNBC migration and survival [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 2657.