TY - JOUR
T1 - The APC/C E3 ligase complex activator fzr1 restricts braf oncogenic function
AU - Wan, Lixin
AU - Chen, Ming
AU - Cao, Juxiang
AU - Dai, Xiangpeng
AU - Yin, Qing
AU - Zhang, Jinfang
AU - Song, Su Jung
AU - Lu, Ying
AU - Liu, Jing
AU - Inuzuka, Hiroyuki
AU - Katon, Jesse M.
AU - Berry, Kelsey
AU - Fung, Jacqueline
AU - Ng, Christopher
AU - Liu, Pengda
AU - Song, Min Sup
AU - Xue, Lian
AU - Bronson, Roderick T.
AU - Kirschner, Marc W.
AU - Cui, Rutao
AU - Pandolfi, Pier Paolo
AU - Wei, Wenyi
N1 - Funding Information:
We thank Brian North, Alan W. Lau, Jianping Guo, Naoe Nihira, and Wenjian Gan for critical reading of the manuscript, William C. Hahn, Peter K. Jackson, Hans R. Widlund, Keiran S. Smalley, and Eric B. Haura for providing reagents, and members of the Wei, Kirschner, Cui, and Pandolfi labs for useful discussions.W. Wei is a Leukemia and Lymphoma Society Scholar and ACS Research Scholar. This work was supported in part by NIH grants (W. Wei, GM089763, GM094777, and CA177910; L. Wan, CA183914) and in part by the Skin SPORE (1P50CA168536) Developmental Research Program (L. Wan).
Publisher Copyright:
©2017 American Association for Cancer Research.
PY - 2017/4
Y1 - 2017/4
N2 - BRAF drives tumorigenesis by coordinating the activation of the RAS/RAF/MEK/ERK oncogenic signaling cascade. However, upstream pathways governing BRAF kinase activity and protein stability remain undefined. Here, we report that in primary cells with active APCFZR1, APCFZR1 earmarks BRAF for ubiquitination-mediated proteolysis, whereas in cancer cells with APC-free FZR1, FZR1 suppresses BRAF through disrupting BRAF dimerization. Moreover, we identified FZR1 as a direct target of ERK and CYCLIN D1/CDK4 kinases. Phosphorylation of FZR1 inhibits APCFZR1, leading to elevation of a cohort of oncogenic APCFZR1 substrates to facilitate melanomagenesis. Importantly, CDK4 and/or BRAF/MEK inhibitors restore APCFZR1 E3 ligase activity, which might be critical for their clinical effects. Furthermore, FZR1 depletion cooperates with AKT hyperactivation to transform primary mel-anocytes, whereas genetic ablation of Fzr1 synergizes with Pten loss, leading to aberrant coactivation of BRAF/ERK and AKT signaling in mice. Our findings therefore reveal a reciprocal suppression mechanism between FZR1 and BRAF in controlling tumorigenesis. SIGNIFICANCE: FZR1 inhibits BRAF oncogenic functions via both APC-dependent proteolysis and APC-independent disruption of BRAF dimers, whereas hyperactivated ERK and CDK4 reciprocally suppress APCFZR1 E3 ligase activity. Aberrancies in this newly defined signaling network might account for BRAF hyperactivation in human cancers, suggesting that targeting CYCLIN D1/CDK4, alone or in combination with BRAF/MEK inhibition, can be an effective anti-melanoma therapy.
AB - BRAF drives tumorigenesis by coordinating the activation of the RAS/RAF/MEK/ERK oncogenic signaling cascade. However, upstream pathways governing BRAF kinase activity and protein stability remain undefined. Here, we report that in primary cells with active APCFZR1, APCFZR1 earmarks BRAF for ubiquitination-mediated proteolysis, whereas in cancer cells with APC-free FZR1, FZR1 suppresses BRAF through disrupting BRAF dimerization. Moreover, we identified FZR1 as a direct target of ERK and CYCLIN D1/CDK4 kinases. Phosphorylation of FZR1 inhibits APCFZR1, leading to elevation of a cohort of oncogenic APCFZR1 substrates to facilitate melanomagenesis. Importantly, CDK4 and/or BRAF/MEK inhibitors restore APCFZR1 E3 ligase activity, which might be critical for their clinical effects. Furthermore, FZR1 depletion cooperates with AKT hyperactivation to transform primary mel-anocytes, whereas genetic ablation of Fzr1 synergizes with Pten loss, leading to aberrant coactivation of BRAF/ERK and AKT signaling in mice. Our findings therefore reveal a reciprocal suppression mechanism between FZR1 and BRAF in controlling tumorigenesis. SIGNIFICANCE: FZR1 inhibits BRAF oncogenic functions via both APC-dependent proteolysis and APC-independent disruption of BRAF dimers, whereas hyperactivated ERK and CDK4 reciprocally suppress APCFZR1 E3 ligase activity. Aberrancies in this newly defined signaling network might account for BRAF hyperactivation in human cancers, suggesting that targeting CYCLIN D1/CDK4, alone or in combination with BRAF/MEK inhibition, can be an effective anti-melanoma therapy.
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UR - http://www.scopus.com/inward/citedby.url?scp=85017180342&partnerID=8YFLogxK
U2 - 10.1158/2159-8290.CD-16-0647
DO - 10.1158/2159-8290.CD-16-0647
M3 - Article
C2 - 28174173
AN - SCOPUS:85017180342
SN - 2159-8274
VL - 7
SP - 424
EP - 441
JO - Cancer discovery
JF - Cancer discovery
IS - 4
ER -