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Comprehensive structure-function analysis reveals gain- and loss-of-function mechanisms impacting oncogenic KRAS
Jason J Kwon1,2,3, Julien Dilly1,2,3, Shengwu Liu1,2
1Department of Medical Oncology, Dana Farber Cancer Institute, Boston, MA, 02115, USA.
Abstract:
To dissect variant-function relationships in the KRAS oncoprotein, we performed deep mutational scanning (DMS) screens for both wild-type and KRASG12D mutant alleles. We defined the spectrum of oncogenic potential for nearly all possible KRAS variants, identifying several novel transforming alleles and elucidating a model to describe the frequency of KRAS mutations in human cancer as a function of transforming potential, mutational probability, and tissue-specific mutational signatures. Biochemical and structural analyses of variants identified in a KRASG12D second-site suppressor DMS screen revealed that attenuation of oncogenic KRAS can be mediated by protein instability and conformational rigidity, resulting in reduced binding affinity to effector proteins, such as RAF and PI3-kinases, or reduced SOS-mediated nucleotide exchange activity. These studies define the landscape of single amino acid alterations that modulate the function of KRAS, providing a resource for the clinical interpretation of KRAS variants and elucidating mechanisms of oncogenic KRAS inactivation for therapeutic exploitation.
Insights
Deep mutational scanning comprehensively mapped KRAS variants, revealing novel oncogenic alleles and mechanisms of inactivation. This work provides a resource for interpreting KRAS mutations and developing targeted cancer therapies.
Area of Science:
- Oncogenic signaling pathways
- Molecular mechanisms of cancer
Background:
- KRAS is a key oncoprotein frequently mutated in human cancers.
- Understanding KRAS variant function is critical for cancer therapy.
Purpose of the Study:
- To comprehensively map the functional landscape of KRAS variants.
- To identify novel oncogenic KRAS alleles and understand their transforming potential.
- To elucidate mechanisms of KRAS inactivation for therapeutic targeting.
Main Methods:
- Deep mutational scanning (DMS) of wild-type and KRASG12D alleles.
- Biochemical and structural analyses of identified KRAS variants.
- Development of a model for KRAS mutation frequency in cancer.
Main Results:
- Defined the oncogenic potential of nearly all KRAS variants, identifying novel transforming alleles.
- Established a model linking mutation frequency to transforming potential, mutational probability, and tissue-specific signatures.
- Identified protein instability and conformational rigidity as mechanisms for KRAS inactivation.
Conclusions:
- KRAS variant landscape characterized, aiding clinical interpretation.
- Mechanisms of oncogenic KRAS inactivation elucidated for therapeutic exploitation.
- Provides a foundational resource for KRAS-driven cancer research.
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