Abstract 5062: Hypoxia-induced amoeboid cancer cell migration

Abstract

Abstract Tumor hypoxia, by elevating hypoxia-inducible factors (HIFs), is an established inducer of epithelial-to-mesenchymal transition (EMT) and subsequent cancer cell invasion and metastasis. However, how hypoxia impacts on tumor cell invasion programs and translates into modes of dissemination of moving tumor cells remains unknown. Using breast cancer (BC) and head and neck cancer (HNC) cells which efficiently invade from multicellular spheroids into 3D fibrillar collagen, we addressed which signaling programs that control cell-cell adhesions, cell-matrix interactions and cytoskeletal dynamics and which modes of tumor cell migration are induced by hypoxia. While both cancer models primarily invaded collectively under normoxic conditions, severe hypoxia (0.2% oxygen) or pharmacological stabilization of HIF-1 using the prolyl hydroxylase inhibitor dimethyloxalylglycine (DMOG) induced EMT-like detachment and migration of single cells into collagen, exhibiting a 2- and 4-fold increase of single BC and HNC cells, respectively. Besides infrequent spindle-shaped movement, hypoxia or DMOG predominantly induced the transition from collective to amoeboid single-cell migration, with blebby amoeboid migration as the predominant migration mode (4- and 3-fold increase for BC and HNC, respectively) next to filopodial amoeboid migration. Hypoxia-induced amoeboid migration is characterized by variably fast and persistent migration, reaching up to several 100 μm/day, mediated by actin-rich filopodial or blebby protrusions at the leading edge. Criteria for amoeboid movement included (i) actin-containing blebs that interacted with collagen structures in a polarized fashion, (ii) weak dependence on matrix-metalloproteinase-mediated collagen remodeling, (iii) low dependence on focalized integrin-mediated matrix adhesions, and (iv) high dependence on RhoA-mediated actomyosin contraction for efficient bleb formation and migration speed. Interference with ROCK signaling using Y-27632 and myosin using blebbistatin significantly inhibited hypoxia-induced amoeboid dissemination and bleb formation. Thus, hypoxia induces plasticity of cancer invasion modes, with efficient blebby amoeboid dissemination as primary outcome. While blebby amoeboid motion is known as a rudimentary migration mode in embryonic stem cells, here we observe blebby amoeboid migration as a simple (low MMP- and integrin dependent) but efficient salvage migration mode of cancer cells under severe hypoxic stress. Citation Format: Veronika te Boekhorst, Liying Jiang, Steffi Lehmann, Alba Zuidema, Peter Friedl. Hypoxia-induced amoeboid cancer cell migration. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 5062.