Abstract 3835: Kindlin-2 complexes containing α6β1 integrin are responsive to hypoxia

Abstract

Abstract The laminin-binding integrins are mechanosensory receptors critical for cell adhesion and structural organization that link the extracellular matrix (ECM) to the cytoskeleton. Integrin α6β1 is associated with prostate cancer (PCa) migration, invasion, metastasis, and decreased cancer-specific survival. Kindlin-2 (FERMT2) is a β1 integrin adaptor and mechanosensory focal adhesion (FA) protein that activates and clusters integrins in response to structural ECM alterations in the tumor microenvironment. Our goal was to determine if integrin-kindlin-2 adhesion complexes (kindlin-2:α6β1) were responsive to hypoxia, a physiologically relevant and altered microenvironment in PCa progression. Five different endpoints were tested including the biochemical analysis of kindlin-2 complexes, qRT-PCR, immunoblotting, immunocytochemistry, and electric cell impedance sensing (ECIS). Using DU145 prostate cancer cells grown under hypoxia (1% O2) for up to 16 hours, the results showed a reversible increase in kindlin-2:α6β1 complexes with maximal assembly within 4 hours and disassembly starting by 8 hours. Notably, kindlin-2:α6β1 complexes were found exclusively within membrane projections and were not observed within hypoxia-inducible paxillin (PXN)-containing FAs. The hypoxia induced kindlin-2:α6β1 complexes and classical FAs were dependent on kindlin-2 as determined by CRISPR-Cas9 heterozygous deletion of FERMT2. Protein co-localization of α6 integrin and PXN with kindlin-2 within membrane projections and FAs, respectively, was also induced under hypoxia. Further, non-invasive ECIS measurements in live cells confirmed functional cell-cell and cell-ECM dynamics driven by hypoxia and requiring kindlin-2. Our results indicate that the kindlin-2:α6β1 complexes are uniquely associated with FA-independent membrane projections induced by hypoxia, a tumor microenvironment associated with aggressive prostate cancer. The novel kindlin-2:α6β1 complexes may represent an actionable pharmacological target for blocking escape of organ confined disease and metastasis promoting steps of human prostate cancer. (Partially supported by NIH grants CA P30 23074, DOD W81XWH-19-1-0455, and NCI R01 CA242226). Citation Format: Daniel Hernandez-Cortes, Jaime M.C. Gard, Beatrice S. Knudsen, Noel A. Warfel, Anne E. Cress. Kindlin-2 complexes containing α6β1 integrin are responsive to hypoxia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3835.