Institute of Biomedicine and Molecular Immunology "A. Monroy" (IBIM), National Research Council (CNR), Palermo, Italy.
Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), University of Palermo, Palermo, Italy.
Sci Rep. 2017 Jun 19;7(1):3841. doi: 10.1038/s41598-017-04185-8.
Cell surface expression of alpha-enolase, a glycolytic enzyme displaying moonlighting activities, has been shown to contribute to the motility and invasiveness of cancer cells through the protein non-enzymatic function of binding plasminogen and enhancing plasmin formation. Although a few recent records indicate the involvement of protein partners in the localization of alpha-enolase to the plasma membrane, the cellular mechanisms underlying surface exposure remain largely elusive. Searching for novel interactors and signalling pathways, we used low-metastatic breast cancer cells, a doxorubicin-resistant counterpart and a non-tumourigenic mammary epithelial cell line. Here, we demonstrate by a combination of experimental approaches that epidermal growth factor (EGF) exposure, like lipopolysaccharide (LPS) exposure, promotes the surface expression of alpha-enolase. We also establish Heat shock protein 70 (Hsp70), a multifunctional chaperone distributed in intracellular, plasma membrane and extracellular compartments, as a novel alpha-enolase interactor and demonstrate a functional involvement of Hsp70 in the surface localization of alpha-enolase. Our results contribute to shedding light on the control of surface expression of alpha-enolase in non-tumourigenic and cancer cells and suggest novel targets to counteract the metastatic potential of tumours.
细胞表面烯醇化酶的表达，一种具有多种活性的糖酵解酶，通过与纤溶酶原结合并增强纤溶酶形成的非酶蛋白功能，促进癌细胞的运动性和侵袭性。尽管最近有一些记录表明蛋白质伴侣参与了烯醇化酶向质膜的定位，但细胞表面暴露的细胞机制在很大程度上仍未被揭示。为了寻找新的相互作用蛋白和信号通路，我们使用低转移性乳腺癌细胞、阿霉素耐药的对应细胞和非肿瘤性乳腺上皮细胞系。在这里，我们通过一系列实验方法证明，表皮生长因子（EGF）暴露，如脂多糖（LPS）暴露，可促进烯醇化酶的表面表达。我们还确定热休克蛋白 70（Hsp70），一种分布在内质网、质膜和细胞外区室的多功能伴侣蛋白，是烯醇化酶的一个新的相互作用蛋白，并证明 Hsp70 参与了烯醇化酶的表面定位。我们的研究结果有助于阐明非肿瘤性和肿瘤细胞中烯醇化酶表面表达的调控，并为对抗肿瘤的转移潜能提供新的靶标。
