LEM4 confers tamoxifen resistance to breast cancer cells by activating cyclin D-CDK4/6-Rb and ER? pathway.

ABSTRACT: The elucidation of molecular events that confer tamoxifen resistance to estrogen receptor ? (ER) positive breast cancer is of major scientific and therapeutic importance. Here, we report that LEM4 overexpression renders ER+ breast cancer cells resistant to tamoxifen by activating the cyclin D-CDK4/6 axis and the ER? signaling. We show that LEM4 overexpression accelerates tumor growth. Interaction with LEM4 stabilizes CDK4 and Rb, promotes Rb phosphorylation and the G1/S phase transition. LEM4 depletion or combined tamoxifen and PD0332991 treatment significantly reverses tamoxifen resistance. Furthermore, LEM4 interacts with and stabilizes both Aurora-A and ER?, promotes Aurora-A mediated phosphorylation of ER?-Ser167, leading to increase in ER? DNA-binding and transactivation activity. Elevated levels of LEM4 correlates with poorer relapse-free survival in patients with ER+ breast cancer undergoing endocrine therapy. Thus, LEM4 represents a prognostic marker and an attractive target for breast cancer therapeutics. Functional antagonism of LEM4 could overcome tamoxifen resistance.

SUBMITTER: Gao A 

PROVIDER: S-EPMC6177406 | biostudies-literature | 2018 Oct

REPOSITORIES: biostudies-literature