Moderate and strong static magnetic fields directly affect EGFR kinase domain orientation to inhibit cancer cell proliferation
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Lei Zhang1,*, Jihao Wang1,2,*, HongLei Wang3,*, Wenchao Wang1, Zhiyuan Li1, Juanjuan Liu1, Xingxing Yang1, Xinmiao Ji1, Yan Luo1, Chen Hu1, Yubin Hou1, Qianqian He1, Jun Fang1, Junfeng Wang1, Qingsong Liu1, Guohui Li3, Qingyou Lu1,2,4, Xin Zhang1
1High Magnetic Field Laboratory, Chinese Academy of Sciences and University of Science and Technology of China, Hefei, Anhui 230026, China
2Hefei National Laboratory for Physical Sciences at The Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China
3Laboratory of Molecular Modeling and Design, State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning 116023, China
4Collaborative Innovation Center of Advanced Microstructure, Nanjing University, Nanjing, Jiangsu 210093, China
*These authors have contributed equally to this work
Xin Zhang, email: firstname.lastname@example.org
Qingyou Lu, email: email@example.com
Guohui Li, email: firstname.lastname@example.org
Keywords: EGFR, magnetic field, STM, cancer
Received: March 09, 2016 Accepted: April 27, 2016 Published: May 19, 2016
Static magnetic fields (SMFs) can affect cell proliferation in a cell-type and intensity-dependent way but the mechanism remains unclear. At the same time, although the diamagnetic anisotropy of proteins has been proposed decades ago, the behavior of isolated proteins in magnetic fields has not been directly observed. Here we show that SMFs can affect isolated proteins at the single molecular level in an intensity-dependent manner. We found that Epidermal Growth Factor Receptor (EGFR), a protein that is overexpressed and highly activated in multiple cancers, can be directly inhibited by SMFs. Using Liquid-phase Scanning Tunneling Microscopy (STM) to examine pure EGFR kinase domain proteins at the single molecule level in solution, we observed orientation changes of these proteins in response to SMFs. This may interrupt inter-molecular interactions between EGFR monomers, which are critical for their activation. In molecular dynamics (MD) simulations, 1-9T SMFs caused increased probability of EGFR in parallel with the magnetic field direction in an intensity-dependent manner. A superconducting ultrastrong 9T magnet reduced proliferation of CHO-EGFR cells (Chinese Hamster Ovary cells with EGFR overexpression) and EGFR-expressing cancer cell lines by ~35%, but minimally affected CHO cells. We predict that similar effects of magnetic fields can also be applied to some other proteins such as ion channels. Our paper will help clarify some dilemmas in this field and encourage further investigations in order to achieve a better understanding of the biological effects of SMFs.
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