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Using cells devoid of RAS proteins as tools for drug discovery
Author(s) -
Urosevic Jelena,
Sum Eleanor Y.M.,
Moneo Victoria,
Drosten Matthias,
Dhawahir Alma,
Becerra Mercedes,
Carnero Amancio,
Barbacid Mariano
Publication year - 2009
Publication title -
molecular carcinogenesis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.254
H-Index - 97
eISSN - 1098-2744
pISSN - 0899-1987
DOI - 10.1002/mc.20555
Subject(s) - biology , kinase , mapk/erk pathway , protein kinase b , microbiology and biotechnology , mitogen activated protein kinase , anti apoptotic ras signalling cascade , p38 mitogen activated protein kinases , cancer research , cell culture , signal transduction , genetics
Abstract Mutational activation of RAS proteins occurs in nearly 30% of all human tumors. To date direct pharmacological inhibition of RAS oncoproteins has not been possible. As a consequence, current strategies are focusing on the development of inhibitors that target those kinases acting downstream of RAS proteins, including those of the RAF/MEK/ERK and PI3K/AKT pathways. Most of these inhibitors have undesired off‐target effects that mask the potential therapeutic effect of blocking their targeted kinases. To facilitate the screening of selective inhibitors, we have generated lines of mouse embryonic fibroblasts that lack endogenous Ras proteins. These cells proliferate due to ectopic expression of either Ras oncoproteins that selectively activate the Raf/Mek/Erk pathway such as H‐Ras G12V/D38E or constitutively active kinases such as B‐Raf and Mek1. These cell lines were exposed to inhibitors against the RAF, MEK, and AKT kinases as well as inhibitors of other kinases known to crosstalk with RAS signaling such as JNK and p38. Amongst all compounds tested, only the MEK inhibitors U0126 and PD0325901, showed the expected specificity pattern. Yet, PD0325901, but not U0126, was able to inhibit a cell line lacking Ras proteins that owed its proliferative properties to loss of p53. Thus, suggesting unexpected off‐target activities for this compound. The use of cell lines whose proliferative properties exclusively depend on selective targets provide a novel strategy to analyze the specificity of selective inhibitors designed against molecular targets implicated in human cancer. © 2009 Wiley‐Liss, Inc.