Inhibition of Ras–effector interactions by cyclic peptides

Wú, Xiànghóng; Upadhyaya, Punit; Villalona‐Calero, Miguel A.; Briesewitz, Roger; Pei, Dehua

doi:10.1039/c2md20329d

Cited by 58 publications

(61 citation statements)

References 24 publications

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“…Hydrolysis of GTP to GDP is the key reaction through which RAS signaling is turned off and is the center of action for oncogenic mutations at G12, G13, and Q61 that impair both intrinsic and GAP-catalyzed hydrolysis (28). The challenge of directly targeting the RAS G-domain, thus, amounts to three approaches, all of which have been attempted with little or moderate success: increasing hydrolysis rates of mutant RAS (29,30), inhibiting the exchange of GDP for GTP (31)(32)(33)(34)(35)(36)(37)(38)(39), or interfering with effector binding and activation (40)(41)(42)(43)(44)(45)(46)(47)(48)(49). Recent efforts based on high-throughput screening of fragments to identify compounds that affect downstream signaling, accompanied by crystal structures that allowed structure-based optimization in some cases, have for the first time provided a high-resolution view of how small molecules are accommodated in binding pockets near the active site to interfere with RAS signaling (33)(34)(35)39).…”

Section: The State Of Small Molecules That Directly Bind Rasmentioning

confidence: 99%

Direct Attack on RAS: Intramolecular Communication and Mutation-Specific Effects

Marcus

Mattos

2015

Clinical Cancer Research

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The crystal structure of RAS was first solved 25 years ago. In spite of tremendous and sustained efforts, there are still no drugs in the clinic that directly target this major driver of human cancers. Recent success in the discovery of compounds that bind RAS and inhibit signaling has fueled renewed enthusiasm, and in-depth understanding of the structure and function of RAS has opened new avenues for direct targeting. To succeed, we must focus on the molecular details of the RAS structure and understand at a high-resolution level how the oncogenic mutants impair function. Structural networks of intramolecular communication between the RAS active site and membraneinteracting regions on the G-domain are disrupted in oncogenic mutants. Although conserved across the isoforms, these networks are near hot spots of protein-ligand interactions with amino acid composition that varies among RAS proteins. These differences could have an effect on stabilization of conformational states of interest in attenuating signaling through RAS. The development of strategies to target these novel sites will add a fresh direction in the quest to conquer RAS-driven cancers.

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Section: The State Of Small Molecules That Directly Bind Rasmentioning

confidence: 99%

Direct Attack on RAS: Intramolecular Communication and Mutation-Specific Effects

Marcus

Mattos

2015

Clinical Cancer Research

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“…[130] Rigidified peptides have been suggested to better address the highly flexible effector binding regions and to offer more druglike properties.T wo combinatorial libraries of cyclized peptides were tested for their potential to bind to K-Ras and to impair the K-Ras-c-Raf interaction. [131,132] Screening of approximately 1.5 million compounds originating from acombinatorial library of bicyclic peptides (3-5 variable residues per ring) yielded four molecules that bind K-Ras-GTP with affinities in the low micromolar range (K d = 0.5 mm-6.8 mm). Thepeptides display ap reference for the GTP-bound state,i nhibit the Ras-Raf interaction in vitro (best IC 50 :1.4 mm), but show only poor antiproliferative activity,most probably because of poor cell penetration.…”

Section: Peptide-based Ras Inhibitorsmentioning

confidence: 99%

“…[132] Another library of six million cyclic peptides containing av ariable stretch of 4-6 residues and aF K506-binding protein 12 (FKBP) binding moiety was generated. [131] By analogy to rapamycin, the FKBP-binding moiety was included to allow formation of ab inary peptide-FKBP complex with increased interaction surface with the target protein. [133] Screening of about 3million compounds yielded several Ras-binding peptide-FKBP complexes.I nterestingly, compound 39 disrupts the interaction of K-Ras G12V and Raf-RBD in vitro with IC 50 values of 0.7 mm,e ven in the absence of FKBP.A ccording to fluorescence polarization (FP) and surface plasmon resonance (SPR) measurements, 39 binds to K-Ras with a K d value of 0.83 mm,b ut does not attenuate MEK or ERK phosphorylation in cells,p ossibly because of insufficient cell penetration (Figure 10 a).…”

Section: Peptide-based Ras Inhibitorsmentioning

confidence: 99%

“…[129] In this context, initial success has been achieved by screening libraries of mono-and bicyclicp eptides which exhibit sub-micromolar affinity and interfere with the RasRaf interaction in vitro (Figure 10). [131,132,134] Thef irst generation of these inhibitors suffered from inefficient cell penetration, but permeability was improved in av ery recent second generation of cyclorasins. [134] Their performance in in vivo studies needs to be investigated for assessment of the full potential of these promising inhibitors of Ras-effector interactions.A saconsequence of their larger interaction surfaces,m acrocycles and stabilized structured peptides are highly interesting compound classes for PPI inhibition, [160] and might provide sufficient binding affinity and selectivity for small GTPase targeting.…”

Section: Inhibition Of Gtpase-effector Interactionsmentioning

confidence: 99%

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Direct Modulation of Small GTPase Activity and Function

et al. 2015

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Small GTPases are a family of GDP-/GTP-binding proteins that serve as biomolecular switches inside cells to control a variety of essential cellular processes. Aberrant function and regulation of small GTPases is associated with a variety of human diseases, thus rendering these proteins highly interesting targets in drug discovery. However, this class of proteins has been considered "undruggable", as intensive decade-long efforts did not yield clinically relevant direct modulators of small GTPases. Recently, the targeting of small GTPases has gained fresh impetus through the discovery of novel transient cavities on the protein surfaces and the application of new targeting strategies. Besides Ras proteins, other small GTPases have attracted increased attention since improved biological insight in combination with novel targeting strategies identified them as promising targets in drug discovery. This Review gives an overview of relevant aspects of the superfamily of small GTPases and summarizes recent progress and perspectives for the direct modulation of these challenging targets.

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“…Finally, a combinatorial screening approach identified several cyclic peptides with submicromolar RAS-binding activity, but no cellular activity was observed (14). Despite the recent progress in developing small molecules and synthetic peptides to directly target RAS or RAS-SOS1, high-affinity binders with promising cellular activity across the broad spectrum of wild-type and mutant KRAS-driven cancers have remained out of reach.…”

mentioning

confidence: 99%

Direct inhibition of oncogenic KRAS by hydrocarbon-stapled SOS1 helices

Leshchiner

Parkhitko²,

Bird

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

148

121

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Activating mutations in the Kirsten rat sarcoma viral oncogene homolog (KRAS) underlie the pathogenesis and chemoresistance of ∼30% of all human tumors, yet the development of high-affinity inhibitors that target the broad range of KRAS mutants remains a formidable challenge. Here, we report the development and validation of stabilized alpha helices of son of sevenless 1 (SAH-SOS1) as prototype therapeutics that directly inhibit wild-type and mutant forms of KRAS. SAH-SOS1 peptides bound in a sequence-specific manner to KRAS and its mutants, and dose-responsively blocked nucleotide association. Importantly, this functional binding activity correlated with SAH-SOS1 cytotoxicity in cancer cells expressing wild-type or mutant forms of KRAS. The mechanism of action of SAH-SOS1 peptides was demonstrated by sequencespecific down-regulation of the ERK-MAP kinase phosphosignaling cascade in KRAS-driven cancer cells and in a Drosophila melanogaster model of Ras85D V12 activation. These studies provide evidence for the potential utility of SAH-SOS1 peptides in neutralizing oncogenic KRAS in human cancer.R AS signaling is a critical control point for a host of cellular functions ranging from cellular survival and proliferation to cellular endocytosis and motility (1). The on or off state of RAS is dictated by nucleotide exchange. GTP-bound RAS is the activated form that engages its downstream effectors with high avidity. The endogenous GTPase activity of RAS hydrolyzes GTP to GDP and inactivates signaling. This biochemical process is further regulated by GTPase-activating proteins (GAPs) that impair RAS signaling through increasing endogenous GTPase activity and guanine-nucleotide exchange factors (GEFs) that enhance RAS signaling by facilitating GDP release and, thus, GTP association. Given the central roles of RAS in cellular growth and metabolism, it is not surprising that cancer cells usurp its prosurvival activities to achieve immortality.Activating mutations in KRAS represent the most frequent oncogenic driving force among the RAS homologs K-, N-, and H-RAS, and are associated with poor prognosis and chemoresistance (2). KRAS mutations are present in ∼30% of human tumors and at even higher frequencies in cancers of the pancreas, lung, thyroid gland, colon, and liver. For example, in pancreatic ductal adenocarcinomas (PDAC) that carry a 5-y survival rate of less than 5%, activating KRAS mutations are present in more than 90% of tumors (3). Thus, therapeutic inhibition of RAS is among the highest priority goals of the cancer field. Because oncogenic forms of KRAS typically harbor single-point mutants that stabilize its active GTP-bound form, a host of recent small molecule and peptide development efforts have been aimed at disarming this pathologic biochemical state. The extremely high affinity of KRAS for its GTP substrate has hampered the development of competitive GTP inhibitors. However, a GDP mimetic that covalently modifies the mutant cysteine of KRAS G12C represents a promising approach to plugging the nucleotid...

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Inhibition of Ras–effector interactions by cyclic peptides

Cited by 58 publications

References 24 publications

Direct Attack on RAS: Intramolecular Communication and Mutation-Specific Effects

Direct Attack on RAS: Intramolecular Communication and Mutation-Specific Effects

Direct Modulation of Small GTPase Activity and Function

Direct inhibition of oncogenic KRAS by hydrocarbon-stapled SOS1 helices

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