Targeting the KRAS α4-α5 allosteric interface inhibits pancreatic cancer tumorigenesis

ABSTRACT

RAS is the most frequently mutated oncogene in human cancer with nearly ~20% of cancer patients possessing mutations in one of three RAS genes (K, N or HRAS). However, KRAS is mutated in nearly 90% of pancreatic ductal carcinomas (PDAC). Although pharmacological inhibition of RAS has been challenging, KRAS(G12C)-specific inhibitors have recently entered the clinic. While KRAS(G12C) is frequently expressed in lung cancers, it is rare in PDAC. Thus, more broadly efficacious RAS inhibitors are needed for treating KRAS mutant-driven cancers such as PDAC. A RAS-specific tool biologic, NS1 Monobody, inhibits HRAS- and KRAS-mediated signalling and oncogenic transformation both in vitro and in vivo by targeting the α4–α5 allosteric site of RAS and blocking RAS self-association. Here, we evaluated the efficacy of targeting the α4-α5 interface of KRAS as an approach to inhibit PDAC development using an immunocompetent orthotopic mouse model. Chemically regulated NS1 expression inhibited ERK and AKT activation in KRAS(G12D) mutant KPC PDAC cells and reduced the formation and progression of pancreatic tumours. NS1-expressing tumours were characterized by increased infiltration of CD4 + T helper cells. These results suggest that targeting the #x3B1;4-#x3B1;5 allosteric site of KRAS may represent a viable therapeutic approach for inhibiting KRAS-mutant pancreatic tumours.

KEYWORDS:

• Pancreatic ductal adenocarcinoma
• tumourigenesis
• Monobody
• T-cell

Acknowledgments

We wish to thank members of the O’Bryan and Ostrowski labs for comments on this work. This work was supported in part by a Merit Review Award (1I01BX002095) from the United States (US) Department of Veterans Affairs Biomedical Laboratory Research and Development Service to J.P.O., an NIH award to J.P.O. and S.K. (CA212608), a Chan Zuckerberg Initiative DAF grant to T.P. (2019-198009), and support from the Hollings Cancer Center. The in vivo imaging was supported in part by the Small Animal Imaging Unit of the Cell & Molecular Imaging Shared Resource, Hollings Cancer Center, Medical University of South Carolina (P30 CA138313). The contents do not represent the views of the US Department of Veterans Affairs or the United States Government.

Disclosure statement

S.K. and A.K. are inventors on a patent that covers designs of monobody libraries (US Patent 9,512,199 B2).

Supplemental Material

Supplemental data for this article can be accessed here.

Author Contributions

I.K., M.C.O. and J.P.O. designed the study; E.D., A.K. and S.K. performed the Monobody affinity experiments; I.K. and M.Z. performed the biochemical and cell biological studies; I.K., C.M-B., J.L., D.M.C. and A.-M.B. performed the animal studies; T.P. and C.T. performed the IHC analyses; I.K. and J.P.O. wrote the manuscript and all authors commented and approved the manuscript.

Additional information

Funding

This work was supported by the National Institutes of Health [CA212608]; National Institutes of Health [P30 CA138313]; US Department of Veterans Affairs [1I01BX002095]; Chan Zuckerberg Initiative DAF grant [2019-198009].