Discovery of Small Molecules that Bind to K‐Ras and Inhibit Sos‐Mediated Activation

Sun, Qi; Burke, Jason P.; Phan, Jason; Burns, Michael C.; Olejniczak, Edward T.; Waterson, Alex G.; Lee, Taekyu; Rossanese, Olivia W.; Fesik, Stephen W.

doi:10.1002/anie.201201358

Cited by 422 publications

(295 citation statements)

References 16 publications

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“…The development of G12C-selective inhibitors that target the thiol in order to inhibit GTP bindinglocking RAS in an inactive state so it cannot interact with its effectorshave been recently described (Hunter et al, 2014;Ostrem et al, 2013). Other molecules that block RAS interaction with the SOS1 RASGEF (Maurer et al, 2012;Sun et al, 2012) or effectors (Shima et al, 2013) have also been identified. Indirect approaches include (ii) inhibition of enzymes that target the RAS CAAX motif in order to prevent membrane association of RAS (e.g.…”

Section: Box 2 Approaches For Targeting Rasmentioning

confidence: 99%

RAS isoforms and mutations in cancer at a glance

Hobbs

Der

Rossman

2016

Journal of Cell Science

666

709

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RAS proteins (KRAS4A, KRAS4B, NRAS and HRAS) function as GDP-GTP-regulated binary on-off switches, which regulate cytoplasmic signaling networks that control diverse normal cellular processes. Gain-of-function missense mutations in RAS genes are found in ∼25% of human cancers, prompting interest in identifying anti-RAS therapeutic strategies for cancer treatment. However, despite more than three decades of intense effort, no anti-RAS therapies have reached clinical application. Contributing to this failure has been an underestimation of the complexities of RAS. First, there is now appreciation that the four human RAS proteins are not functionally identical. Second, with >130 different missense mutations found in cancer, there is an emerging view that there are mutation-specific consequences on RAS structure, biochemistry and biology, and mutation-selective therapeutic strategies are needed. In this Cell Science at a Glance article and accompanying poster, we provide a snapshot of the differences between RAS isoforms and mutations, as well as the current status of anti-RAS drug-discovery efforts.

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Section: Box 2 Approaches For Targeting Rasmentioning

confidence: 99%

RAS isoforms and mutations in cancer at a glance

Hobbs

Der

Rossman

2016

Journal of Cell Science

666

709

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“…B-Raf inhibitors also paradoxically activate the mitogen-activated protein kinase (MAPK) cascade in melanoma cells expressing oncogenic mutant N-or K-Ras (4-6). Other highly promising approaches include compounds that covalently modify K-Ras proteins with a G12C mutation to abrogate effector interactions (7,8) and allosteric modulators that directly bind Ras to inhibit guanine nucleotide exchange factor (GEF)-mediated nucleotide exchange (9)(10)(11). Chronic inhibition of Ras-GEF binding reduces GTP loading of oncogenic mutant K-Ras and hence inhibits K-Ras signaling activity (11).…”

mentioning

confidence: 99%

Inhibition of Acid Sphingomyelinase Depletes Cellular Phosphatidylserine and Mislocalizes K-Ras from the Plasma Membrane

Cho

Hoeven

Zhou

et al. 2016

Molecular and Cellular Biology

143

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e K-Ras must localize to the plasma membrane for biological activity; thus, preventing plasma membrane interaction blocks KRas signal output. Here we show that inhibition of acid sphingomyelinase (ASM) mislocalizes both the K-Ras isoforms K-Ras4A and K-Ras4B from the plasma membrane to the endomembrane and inhibits their nanoclustering. We found that fendiline, a potent ASM inhibitor, reduces the phosphatidylserine (PtdSer) and cholesterol content of the inner plasma membrane. These lipid changes are causative because supplementation of fendiline-treated cells with exogenous PtdSer rapidly restores K-Ras4A and K-Ras4B plasma membrane binding, nanoclustering, and signal output. Conversely, supplementation with exogenous cholesterol restores K-Ras4A but not K-Ras4B nanoclustering. These experiments reveal different operational pools of PtdSer on the plasma membrane. Inhibition of ASM elevates cellular sphingomyelin and reduces cellular ceramide levels. Concordantly, delivery of recombinant ASM or exogenous ceramide to fendiline-treated cells rapidly relocalizes K-Ras4B and PtdSer to the plasma membrane. K-Ras4B mislocalization is also recapitulated in ASM-deficient Neimann-Pick type A and B fibroblasts. This study identifies sphingomyelin metabolism as an indirect regulator of K-Ras4A and K-Ras4B signaling through the control of PtdSer plasma membrane content. It also demonstrates the critical and selective importance of PtdSer to K-Ras4A and K-Ras4B plasma membrane binding and nanoscale spatial organization. Ras proteins are small guanine nucleotide binding proteins that oscillate between active GTP-bound and inactive GDP-bound states. Activated Ras proteins transmit signals for cell proliferation and cell survival. Importantly, ϳ15% of all human tumors express mutant Ras proteins that are locked in the GTP-bound state (1). Of the three ubiquitously expressed Ras isoforms, H-, N-, and K-Ras, oncogenic mutant K-Ras is the most prevalent, being expressed in ϳ95% of pancreatic, ϳ45% of colorectal, and ϳ35% of lung cancers (1). Despite its importance, there are currently no clinically approved drugs that directly target oncogenic K-Ras. To date, Ras drug discovery efforts have focused largely on inhibitors of Ras downstream effectors, including B-Raf, C-Raf, phosphatidylinositol 3-kinase (PI3K), MEK, and extracellular signal-regulated kinase (ERK) (2). For example, B-Raf-specific inhibitors produce excellent albeit often short-lived responses in patients with B-Raf mutant melanoma (3), in part because of a perturbation of complex negative-feedback control loops (2). B-Raf inhibitors also paradoxically activate the mitogen-activated protein kinase (MAPK) cascade in melanoma cells expressing oncogenic mutant N-or K-Ras (4-6). Other highly promising approaches include compounds that covalently modify K-Ras proteins with a G12C mutation to abrogate effector interactions (7,8) and allosteric modulators that directly bind Ras to inhibit guanine nucleotide exchange factor (GEF)-mediated nucleotide exchange (9-11). Chronic i...

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“…This is why FBDD is patronized to find starting binders to tough targets that have been presumed undruggable. 5,6 Lastly, if the binding mode of hits is structurally elucidated, a subsequent hit-to-lead optimization is more easily accomplished by expanding from the direct binding moieties with only a few compounds. Generally, hits from FBDD have low functionality and correspondingly weaker binding affinity (mM ~ 10 uM) than that of most hits from HTS (10 uM ~ nM).…”

Section: Fragment-based Drug Discoverymentioning

confidence: 99%

NMR methods in fragment based drug discovery

Jongsoo¹

2015

Journal of the Korean Magnetic Resonance Society

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Nuclear magnetic resonance (NMR) spectroscopy, owing to its ability to provide atomic level information on molecular structure, dynamics and interaction, has become one of the most powerful methods in early drug discovery where hit finding and hit-to-lead generation are mainly pursued. In recent years, drug discovery programs originating from the fragment-based drug discovery (FBDD) strategies have been widely incorporated into academia and industry in which a wide variety of NMR methods become an indispensable arsenal to elucidate the binding of small molecules onto bimolecular targets. In this review, I briefly describe FBDD and introduce NMR methods mainly used in FBDD campaigns of my company. In addition, quality control of fragment library and practical NMR methods in industrial aspect are discussed shortly.

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Discovery of Small Molecules that Bind to K‐Ras and Inhibit Sos‐Mediated Activation

Cited by 422 publications

References 16 publications

RAS isoforms and mutations in cancer at a glance

RAS isoforms and mutations in cancer at a glance

Inhibition of Acid Sphingomyelinase Depletes Cellular Phosphatidylserine and Mislocalizes K-Ras from the Plasma Membrane

NMR methods in fragment based drug discovery

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