Aurora kinase A promotes AR degradation via the E3 ligase CHIP

S Sarkar, DL Brautigan, JM Larner - Molecular Cancer Research, 2017 - AACR
S Sarkar, DL Brautigan, JM Larner
Molecular Cancer Research, 2017AACR
Reducing the levels of the androgen receptor (AR) is one of the most viable approaches to
combat castration-resistant prostate cancer. Previously, we observed that proteasomal-
dependent degradation of AR in response to 2-methoxyestradiol (2-ME) depends primarily
on the E3 ligase C-terminus of HSP70-interacting protein (STUB1/CHIP). Here, 2-ME
stimulation activates CHIP by phosphorylation via Aurora kinase A (AURKA). Aurora A
kinase inhibitors and RNAi knockdown of Aurora A transcript selectively blocked CHIP …
Abstract
Reducing the levels of the androgen receptor (AR) is one of the most viable approaches to combat castration-resistant prostate cancer. Previously, we observed that proteasomal-dependent degradation of AR in response to 2-methoxyestradiol (2-ME) depends primarily on the E3 ligase C-terminus of HSP70-interacting protein (STUB1/CHIP). Here, 2-ME stimulation activates CHIP by phosphorylation via Aurora kinase A (AURKA). Aurora A kinase inhibitors and RNAi knockdown of Aurora A transcript selectively blocked CHIP phosphorylation and AR degradation. Aurora A kinase is activated by 2-ME in the S-phase as well as during mitosis, and phosphorylates CHIP at S273. Prostate cancer cells expressing an S273A mutant of CHIP have attenuated AR degradation upon 2-ME treatment compared with cells expressing wild-type CHIP, supporting the idea that CHIP phosphorylation by Aurora A activates its E3 ligase activity for the AR. These results reveal a novel 2-ME→Aurora A→CHIP→AR pathway that promotes AR degradation via the proteasome that may offer novel therapeutic opportunities for prostate cancer. Mol Cancer Res; 15(8); 1063–72. ©2017 AACR.
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