Abstract 5418: Lamellipodial protrusions induced by hypoxia depend upon kindlin-2 in prostate cancer cells
Authors: Nelson Colin , Hernandez-Cortes Daniel , Marr Kendra D. , Gard Jaime MC , Paxson Allan I. , Harryman William L. , Seppanen Natalya K. , Ryniawec John M. , Cress Anne E. 
Published: March 2024

Abstract
Hypoxia is a physiologically relevant feature of the prostate microenvironment that promotes migration and invasion resulting in extracapsular extension, the first step toward metastatic progression. Prostate cancer invasion depends on integrins as mechanosensing membrane receptors during creation of membrane lamellipodial protrusions and focal adhesions (FAs). The objective of this study was to determine the molecular events that promote membrane protrusions under hypoxia and whether this was dependent upon kindlin-2, an essential integrin adapter that marks activated β1 integrin heterodimers. DU145 cells depleted of one copy of FERMT2+/- (50% kindlin-2 expression) by CRISPR/Cas9 or DU145 FERMT2wt (normal kindlin-2 expression) were grown under acute exposure to hypoxia (1% O2) and compared to cells grown under normal tissue culture conditions. Immunofluorescence microscopy experiments were performed to analyze the spatial temporal expression of kindlin-2 complexes. Kindlin-2 complexes were confirmed by immunoprecipitation using an anti-kindlin-2 3A3-antibody from Sigma-Aldrich. Colocalization was determined by obtaining 2D immunofluorescence microscopy images analyzed using ImageJ 2.1.0/1.53c and Nikon NIS-Elements 5.30.04. Under hypoxic conditions, analysis over four time points (4h, 8h, 12h & 16h) increased the number and area of FAs (marked by paxillin (PXN)) containing kindlin-2 in a time-dependent manner by 2-fold and 1.5-fold, respectively, but not in DU145 FERMT2+/- cells. Additionally, hypoxia increased membrane area, perimeter, and the plasma membrane intensity of kindlin-2 exclusive of FAs in DU145 FERMT2wt cells which was maximal after 8 hours of hypoxia. Interestingly, limiting the kindlin-2 expression in FERMT2+/- cells resulted in a loss of hypoxia-induced lamellipodial protrusions (marked by lamellipodin (RAPH1)) containing kindlin-2 while hypoxia-induced kindlin-2 FA changes were preserved. The current working hypothesis is that lamellipodial protrusions are dependent upon kindlin-2 expression whereas the established FAs are stable under conditions of reduced kindlin-2 expression in hypoxia. This data suggests that an early stage of migration, lamellipodial extensions are sensitive to kindlin-2 availability. Further studies are required to determine the dynamic interplay between protrusive events and focal adhesions in relation to kindlin-2 for prostate cancer cells to migrate and invade.
Citation Format: Colin Nelson, Daniel Hernandez-Cortes, Kendra D. Marr, Jaime MC Gard, Allan I. Paxson, William L. Harryman, Natalya K. Seppanen, John M. Ryniawec, Anne E. Cress. Lamellipodial protrusions induced by hypoxia depend upon kindlin-2 in prostate cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5418.