Reactivation of mitogen-activated protein kinase (MAPK) pathway by FGF receptor 3 (FGFR3)/Ras mediates resistance to vemurafenib in human B-RAF V600E mutant melanoma.
Oncogenic B-RAF V600E mutation is found in 50% of melanomas and drives MEK/ERK pathway and cancer progression. Recently, a selective B-RAF inhibitor, vemurafenib (PLX4032), received clinical approval for treatment of melanoma with B-RAF V600E mutation. However, patients on vemurafenib eventually develop resistance to the drug and demonstrate tumor progression within an average of 7 months. Recent reports indicated that multiple complex and context-dependent mechanisms may confer resistance to B-RAF inhibition. In the study described herein, we generated B-RAF V600E melanoma cell lines of acquired-resistance to vemurafenib, and investigated the underlying mechanism(s) of resistance. Biochemical analysis revealed that MEK/ERK reactivation through Ras is the key resistance mechanism in these cells. Further analysis of total gene expression by microarray confirmed a significant increase of Ras and RTK gene signatures in the vemurafenib-resistant cells. Mechanistically, we found that the enhanced activation of fibroblast growth factor receptor 3 (FGFR3) is linked to Ras and MAPK activation, therefore conferring vemurafenib resistance. Pharmacological or genetic inhibition of the FGFR3/Ras axis restored the sensitivity of vemurafenib-resistant cells to vemurafenib. Additionally, activation of FGFR3 sufficiently reactivated Ras/MAPK signaling and conferred resistance to vemurafenib in the parental B-RAF V600E melanoma cells. Finally, we demonstrated that vemurafenib-resistant cells maintain their addiction to the MAPK pathway, and inhibition of MEK or pan-RAF activities is an effective therapeutic strategy to overcome acquired-resistance to vemurafenib. Together, we describe a novel FGFR3/Ras mediated mechanism for acquired-resistance to B-RAF inhibition. Our results have implications for the development of new therapeutic strategies to improve the outcome of patients with B-RAF V600E melanoma.
Oncology Discovery Research, Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana 46285, USA.
Vipin
V
Yadav
Xiaoyi
X
Zhang
Jiangang
J
Liu
Shawn
S
Estrem
Shuyu
S
Li
Xue-Qian
XQ
Gong
Sean
S
Buchanan
James R
JR
Henry
James J
JJ
Starling
Sheng-Bin
SB
Peng
D019943:Amino Acid Substitution; D045744:Cell Line, Tumor; D019008:Drug Resistance, Neoplasm / Q000187:drug effects* / Q000235:genetics; D004789:Enzyme Activation / Q000187:drug effects / Q000235:genetics; D006801:Humans; D007211:Indoles / Q000494:pharmacology*; D020935:MAP Kinase Signaling System / Q000187:drug effects* / Q000235:genetics; D008545:Melanoma / Q000188:drug therapy / Q000201:enzymology* / Q000235:genetics; D020125:Mutation, Missense; D048493:Proto-Oncogene Proteins B-raf / Q000378:metabolism*; D051498:Receptor, Fibroblast Growth Factor, Type 3 / Q000235:genetics / Q000378:metabolism*; D013449:Sulfonamides / Q000494:pharmacology*; D000077484:Vemurafenib; D018631:ras Proteins / Q000235:genetics / Q000378:metabolism*
D007211:Indoles; D013449:Sulfonamides; D000077484:Vemurafenib; C496365:FGFR3 protein, human; D051498:Receptor, Fibroblast Growth Factor, Type 3; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf; D018631:ras Proteins