1. Academic Validation
  2. Activating mutations in MEK1 enhance homodimerization and promote tumorigenesis

Activating mutations in MEK1 enhance homodimerization and promote tumorigenesis

  • Sci Signal. 2018 Oct 30;11(554):eaar6795. doi: 10.1126/scisignal.aar6795.
Jimin Yuan 1 Wan Hwa Ng 1 Zizi Tian 2 Jiajun Yap 1 Manuela Baccarini 3 Zhongzhou Chen 2 Jiancheng Hu 4 5
Affiliations

Affiliations

  • 1 Division of Cellular and Molecular Research, National Cancer Centre Singapore, 11 Hospital Drive, 169610 Singapore, Singapore.
  • 2 State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing 100193, China.
  • 3 Max F. Perutz Laboratories, University of Vienna, Doktor-Bohr-Gasse 9, 1030 Vienna, Austria.
  • 4 Division of Cellular and Molecular Research, National Cancer Centre Singapore, 11 Hospital Drive, 169610 Singapore, Singapore. hu.jiancheng@nccs.com.sg.
  • 5 Cancer and Stem Cell Program, Duke-NUS Medical School, 8 College Road, 169857 Singapore, Singapore.
Abstract

RAS-RAF-MEK-ERK signaling has a well-defined role in Cancer biology. Although aberrant pathway activation occurs mostly upstream of the kinase MEK, mutations in MEK are prevalent in some Cancer subsets. Here, we found that cancer-related, activating mutations in MEK can be classified into two groups: those that relieve inhibitory interactions with the helix A region and those that are in-frame deletions of the β3-αC loop, which enhance MEK1 homodimerization. The former, helix A-associated mutants, are inhibited by traditional MEK inhibitors. However, we found that the increased homodimerization associated with the loop-deletion mutants promoted intradimer cross-phosphorylation of the activation loop and conferred differential resistance to MEK inhibitors both in vitro and in vivo. MEK1 dimerization was required both for its activation by the kinase Raf and for its catalytic activity toward the kinase ERK. Our findings not only identify a previously unknown group of MEK mutants and provide insight into some key steps in RAF-MEK-ERK activation but also have implications for the design of therapies targeting RAS-ERK signaling in cancers.

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