Abstract 1521: New roles of ATP in metastasis: Extracellular and macropinocytosis internalized ATP work together to induces epithelial to mesenchymal transition and other early steps of metastasis

Abstract

Abstract Metastasis is estimated to be responsible for more than 90% of all cancer-related deaths. Metastasis is initiated by induction of epithelial-mesenchymal transition (EMT) of cancer cells, but factors and mechanisms involved in EMT are far from being fully elucidated. Intratumoral extracellular ATP (eATP), at levels of 100-700 μM or 103 to 104 times higher than in normal tissues, has been known to induce epithelial-mesenchymal-transition (EMT) of cancer cells via purinergic receptor signaling. However, the exact induction mechanisms are far from fully known. We previously described that eATP is internalized by cancer cells in vitro and in vivo by macropinocytosis in human non-small cell lung cancer cells, drastically elevates intracellular ATP levels, enhances cell proliferation and resistance to anticancer drugs. In this study, we tested the hypothesis that eATP and macropinocytosis-internalized eATP also induces EMT and other early steps of metastasis. Here we report that eATP, at the concentrations reported in tumors, potently induces expression of matrix metallopeptidases (MMPs), detachment, EMT, migration, and invasion of lung cancer cells. The induction was independent of TGF-β and semi-independent of P2X7 activation. eATP performs these functions not only extracellularly, but also intracellularly after being macropinocytically internalized to further enhance P2X7-mediated EMT, filopodia formation and other early steps of metastasis. The knockout of the macropinocytosis-associated SNX5 gene significantly reduces macropinocytosis and slows down tumor growth in nude mice. Collectively, these results show that eATP functions on these processes not only from outside of cancer cells but also inside after being macropinocytotically internalized. These findings which shed light on eATP's initiator and effector roles in almost every step in early metastasis call for rethinking and rebalancing energy equations of intracellular biochemical reactions and the Warburg effect, and identify eATP and macropinocytosis as novel targets for potentially slowing down EMT, preventing metastasis, and reducing metastasis-related death in cancer patients. Citation Format: Yanyang Cao, Xuan Wang, Maria Evers, Yunsheng Li, Haiyun Zhang, Xiaozhuo Chen. New roles of ATP in metastasis: Extracellular and macropinocytosis internalized ATP work together to induces epithelial to mesenchymal transition and other early steps of metastasis [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1521.