Wnt信号通路
癌症研究
结直肠癌
MEK抑制剂
癌症
黑色素瘤
MAPK/ERK通路
激酶
连环素
医学
信号转导
生物
内科学
细胞生物学
作者
Guangming Chen,Chenxi Gao,Xuan Gao,Dennis Han Zhang,Shih–Fan Kuan,Timothy F. Burns,Jing Hu
标识
DOI:10.1158/1535-7163.mct-17-0561
摘要
Abstract One of the most encouraging developments in oncology has been the success of BRAF inhibitors in BRAF-mutant melanoma. However, in contrast to its striking efficacy in BRAF-mutant melanomas, BRAF inhibitor monotherapy is ineffective in BRAF-mutant colorectal cancer. Although many studies on BRAF inhibitor resistance in colorectal cancer have focused on mechanisms underlying the reactivation of the EGFR/RAS/RAF/MEK/ERK pathway, the current study focuses on identifying novel adaptive signaling mechanisms, a fresh angle on colorectal cancer resistance to BRAF inhibition. We found that treatment with BRAF inhibitors (both current and next-generation BRAF inhibitors) upregulated the Wnt/β-catenin pathway in BRAFV600E-mutant colorectal cancer cell lines through activating the cytoplasmic tyrosine kinase focal adhesion kinase (FAK). The results showed that FAK activation upon BRAF inhibitor treatment did not require EGFR or ERK1/2 activation, implying that BRAF inhibitor treatment-induced hyperactivation of Wnt signaling is “pathway reactivation”-independent. BRAF inhibition–induced Wnt pathway activation was further validated in preclinical models of BRAFV600E-mutant colorectal cancer, including cell line xenograft model and a patient-derived xenograft model. Combined inhibition of BRAF/Wnt pathways or BRAF/FAK pathways exerted strong synergistic antitumor effects in cell culture model and mouse xenograft model. Overall, the current study has identified activation of the Wnt/β-catenin pathway as a novel fundamental cause of colon cancer resistance to BRAF inhibition. Our results suggest that although complete vertical pathway blockade is pivotal for effective and durable control of BRAF-mutant colorectal cancer, cotargeting parallel adaptive signaling—the Wnt/β-catenin pathway—is also essential. Mol Cancer Ther; 17(4); 806–13. ©2017 AACR.
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