V600EBRAF is associated with disabled feedback inhibition of RAF–MEK signaling and elevated transcriptional output of the pathway

CA Pratilas, BS Taylor, Q Ye, A Viale… - Proceedings of the …, 2009 - National Acad Sciences
Proceedings of the National Academy of Sciences, 2009National Acad Sciences
Tumors with mutant BRAF and those with receptor tyrosine kinase (RTK) activation have
similar levels of phosphorylated ERK, but only the former depend on ERK signaling for
proliferation. The mitogen-activated protein kinase, extracellular signal-regulated kinase
kinase (MEK)/ERK-dependent transcriptional output was defined as the genes whose
expression changes significantly 8 h after MEK inhibition. In V600EBRAF cells, this output is
comprised of 52 genes, including transcription factors that regulate transformation and …
Tumors with mutant BRAF and those with receptor tyrosine kinase (RTK) activation have similar levels of phosphorylated ERK, but only the former depend on ERK signaling for proliferation. The mitogen-activated protein kinase, extracellular signal-regulated kinase kinase (MEK)/ERK-dependent transcriptional output was defined as the genes whose expression changes significantly 8 h after MEK inhibition. In V600EBRAF cells, this output is comprised of 52 genes, including transcription factors that regulate transformation and members of the dual specificity phosphatase and Sprouty gene families, feedback inhibitors of ERK signaling. No such genes were identified in RTK tumor cells, suggesting that ERK pathway signaling output is selectively activated in BRAF mutant tumors. We find that RAF signaling is feedback down-regulated in RTK cells, but is insensitive to this feedback in BRAF mutant tumors. Physiologic feedback inhibition of RAF/MEK signaling down-regulates ERK output in RTK cells; evasion of this feedback in mutant BRAF cells is associated with increased transcriptional output and MEK/ERK-dependent transformation.
National Acad Sciences