DIRAS3 broadly suppresses signaling from diverse oncogenic KRAS hotspot variants through an inhibitory interface
- 1Department of Experimental Therapeutics, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
Abstract
Despite major advances in KRAS-directed therapies, broadly suppressing oncogenic KRAS signaling across diverse hotspot variants remains an unmet challenge. Here, we identify an endogenous inhibitory mechanism that suppresses signaling across the major oncogenic KRAS hotspot classes while largely sparing basal wild-type KRAS, revealing activation-state-selective inhibition. We demonstrate that the imprinted tumor suppressor DIRAS3 directly engages activated KRAS through a functionally defined inhibitory interface that can be molecularly mimicked to broadly inhibit KRAS-driven signaling. Using genetically controlled RASless reconstitution models, complementary cancer cell validation, structure-function analyses, molecular dynamics-based membrane topology modeling, and ultrastructural imaging, we show that dual lipid modification constrains DIRAS3 membrane topology, enabling an 5-encoded inhibitory interface to engage activated KRAS, disrupt signaling-competent membrane assemblies, and suppress downstream signaling. Structure-function analyses establish this interface as a critical determinant of DIRAS3-mediated KRAS inhibition. A conformationally constrained 5 mimetic recapitulates full-length DIRAS3 activity, broadly suppressing MAPK and PI3K signaling across multiple oncogenic KRAS variants, including Q61 mutants with reduced sensitivity to current tri-complex RAS(ON) inhibitors. Mechanistically, immunoprecipitation shows that the 5 mimetic reduces KRAS association with both RAF1 and p110 similarly across G12 and Q61 mutants, whereas RMC-7977 reduces inhibition of p110 association with Q61 KRAS. The 5 mimetic also disrupts KRAS nanocluster organization and inhibits tumor growth in vivo. These findings identify a targetable inhibitory interface within DIRAS3 and establish mimicry of an endogenous KRAS suppressor as a mechanistically distinct strategy for broad KRAS inhibition.
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BibTeX
@misc{bildik2026diras3,
title = {{DIRAS3 broadly suppresses signaling from diverse oncogenic KRAS hotspot variants through an inhibitory interface}},
author = {G. Bildik and H. Yang and W. Mao and R. B. Gannaban and V. K. Bhardwaj and M. N. Uddin and S. Y. Jung and M. Pierobon and A. Gomeiz and A. A. Gorfe and J. F. Hancock and C. B. Marshall and F. McCormick and S. W. Millward and J. Liu and R. C. Bast and Z. Lu},
howpublished = {bioRxiv},
year = {2026},
month = oct,
doi = {10.64898/2026.10.21.760748},
url = {https://www.biorxiv.org/content/10.64898/2026.10.21.760748v1},
note = {CC BY-NC-ND},
}
RIS
TY - UNPB
TI - DIRAS3 broadly suppresses signaling from diverse oncogenic KRAS hotspot variants through an inhibitory interface
AU - G. Bildik
AU - H. Yang
AU - W. Mao
AU - R. B. Gannaban
AU - V. K. Bhardwaj
AU - M. N. Uddin
AU - S. Y. Jung
AU - M. Pierobon
AU - A. Gomeiz
AU - A. A. Gorfe
AU - J. F. Hancock
AU - C. B. Marshall
AU - F. McCormick
AU - S. W. Millward
AU - J. Liu
AU - R. C. Bast
AU - Z. Lu
PY - 2026
DA - 2026/10/21
PB - bioRxiv
DO - 10.64898/2026.10.21.760748
UR - https://www.biorxiv.org/content/10.64898/2026.10.21.760748v1
AB - Despite major advances in KRAS-directed therapies, broadly suppressing oncogenic KRAS signaling across diverse hotspot variants remains an unmet challenge. Here, we identify an endogenous inhibitory mechanism that suppresses signaling across the major oncogenic KRAS hotspot classes while largely sparing basal wild-type KRAS, revealing activation-state-selective inhibition. We demonstrate that the imprinted tumor suppressor DIRAS3 directly engages activated KRAS through a functionally defined inhibitory interface that can be molecularly mimicked to broadly inhibit KRAS-driven signaling. Using genetically controlled RASless reconstitution models, complementary cancer cell validation, structure-function analyses, molecular dynamics-based membrane topology modeling, and ultrastructural imaging, we show that dual lipid modification constrains DIRAS3 membrane topology, enabling an 5-encoded inhibitory interface to engage activated KRAS, disrupt signaling-competent membrane assemblies, and suppress downstream signaling. Structure-function analyses establish this interface as a critical determinant of DIRAS3-mediated KRAS inhibition. A conformationally constrained 5 mimetic recapitulates full-length DIRAS3 activity, broadly suppressing MAPK and PI3K signaling across multiple oncogenic KRAS variants, including Q61 mutants with reduced sensitivity to current tri-complex RAS(ON) inhibitors. Mechanistically, immunoprecipitation shows that the 5 mimetic reduces KRAS association with both RAF1 and p110 similarly across G12 and Q61 mutants, whereas RMC-7977 reduces inhibition of p110 association with Q61 KRAS. The 5 mimetic also disrupts KRAS nanocluster organization and inhibits tumor growth in vivo. These findings identify a targetable inhibitory interface within DIRAS3 and establish mimicry of an endogenous KRAS suppressor as a mechanistically distinct strategy for broad KRAS inhibition.
ER -