Reference Detail

Ref Type

Journal Article

PMID

(21705440)

Authors

Wang H, Daouti S, Li WH, Wen Y, Rizzo C, Higgins B, Packman K, Rosen N, Boylan JF, Heimbrook D, Niu H

Title

Identification of the MEK1(F129L) activating mutation as a potential mechanism of acquired resistance to MEK inhibition in human cancers carrying the B-RafV600E mutation.

Journal	Vol	Issue	Date	Pages	Journal Short Title
Cancer research	71	16	2011 Aug 15	5535-45	Cancer Res

URL

Abstract Text

Although targeting the Ras/Raf/MEK pathway remains a promising anticancer strategy, mitogen-activated protein/extracellular signal-regulated kinase (ERK) kinase (MEK) inhibitors in clinical development are likely to be limited in their ability to produce durable clinical responses due to the emergence of acquired drug resistance. To identify potential mechanisms of such resistance, we established MEK inhibitor-resistant clones of human HT-29 colon cancer cells (HT-29R cells) that harbor the B-RafV600E mutation. HT-29R cells were specifically resistant to MEK inhibition in vitro and in vivo, with drug-induced elevation of MEK/ERK and their downstream targets primarily accountable for drug resistance. We identified MEK1(F129L) mutation as a molecular mechanism responsible for MEK/ERK pathway activation. In an isogenic cell system that extended these findings into other cancer cell lines, the MEK1(F129L) mutant exhibited higher intrinsic kinase activity than wild-type MEK1 [MEK1(WT)], leading to potent activation of ERK and downstream targets. The MEK1(F129L) mutation also strengthened binding to c-Raf, suggesting an underlying mechanism of higher intrinsic kinase activity. Notably, the combined use of Raf and MEK inhibitors overcame the observed drug resistance and exhibited greater synergy in HT-29R cells than the drug-sensitive HT-29 parental cells. Overall, our findings suggested that mutations in MEK1 can lead to acquired resistance in patients treated with MEK inhibitors and that a combined inhibition of Raf and MEK may be potentially useful as a strategy to bypass or prevent drug resistance in the clinic.

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Molecular Profile	Treatment Approach

Gene Name	Source	Synonyms	Protein Domains	Gene Description	Gene Role

Therapy Name	Drugs	Efficacy Evidence	Clinical Trials

Drug Name	Trade Name	Synonyms	Drug Classes	Drug Description

Gene	Variant	Impact	Protein Effect	Variant Description	Associated with drug Resistance
MAP2K1	F129L	missense	gain of function	MAP2K1 F129L lies within the protein kinase domain of the Map2k1 protein (UniProt.org). F129L confers a gain of function to the Map2k1 protein as demonstrated by increased kinase activity compared to wild-type, activation of downstream Erk signaling, and increased binding affinity to c-Raf (PMID: 21705440) and also demonstrates resistance to some Mek and Braf inhibitors (PMID: 29753091).	Y

Molecular Profile	Indication/Tumor Type	Response Type	Therapy Name	Approval Status	Evidence Type	Efficacy Evidence	References
MAP2K1 F129L	colorectal cancer	sensitive	RO4927350	Preclinical - Cell line xenograft	Actionable	In a preclinical study, a colorectal cancer cell line harboring MAP2K1 F129L demonstrated sensitivity to treatment with RO4927350 in culture and in cell line xenograft models, demonstrating inhibition of tumor growth (PMID: 21705440).	21705440