Lipid rafts play a key role in the regulation of fundamentally important cellular processes, including cell proliferation, differentiation, and survival. The composition of such
detergent-resistant microdomains (DRMs) is altered under pathologic conditions, including
cancer. Although DRMs have been analyzed in
colorectal carcinoma little information exists about their composition upon treatment with targeted drugs. Hence, a quantitative proteomic profiling approach was performed to define alterations within the DRM fraction of
colorectal carcinoma cells upon treatment with the drug
U0126, an inhibitor of the
mitogen-activated protein kinase pathway. Comparative expression profilings resulted in the identification of 300
proteins, which could partially be linked to key oncogenic signaling pathways and
tumor-related cellular features, such as cell proliferation, adhesion, motility, invasion, and apoptosis resistance. Most of these
proteins were downregulated upon inhibitor treatment. In addition, quantitative proteomic profilings of
cholesterol-depleted versus intact
lipid rafts were performed to define, which U0126-regulated target structures represent bona fide raft
proteins. Selected differentially abundant raft
proteins were validated at the
mRNA and/or
protein level using U0126- or
Trametinib-treated cells. The presented data provide insights into the molecular mechanisms associated with the response to the treatment with
MEK inhibitors and might also lead to novel candidates for therapeutic interventions.