The Q61H mutation decouples KRAS from upstream regulation and renders cancer cells resistant to SHP2 inhibitors

Abstract

Cancer cells bearing distinct KRAS mutations exhibit variable sensitivity to SHP2 inhibitors (SHP2i). Here we show that cells harboring KRAS Q61H are uniquely resistant to SHP2i, and investigate the underlying mechanisms using biophysics, molecular dynamics, and cell-based approaches. Q61H mutation impairs intrinsic and GAP-mediated GTP hydrolysis, and impedes activation by SOS1, but does not alter tyrosyl phosphorylation. Wild-type and Q61H-mutant KRAS are both phosphorylated by Src on Tyr32 and Tyr64 and dephosphorylated by SHP2, however, SHP2i does not reduce ERK phosphorylation in KRAS Q61H cells. Phosphorylation of wild-type and Gly12-mutant KRAS, which are associated with sensitivity to SHP2i, confers resistance to regulation by GAP and GEF activities and impairs binding to RAF, whereas the near-complete GAP/GEF-resistance of KRAS Q61H remains unaltered, and high-affinity RAF interaction is retained. SHP2 can stimulate KRAS signaling by modulating GEF/GAP activities and dephosphorylating KRAS, processes that fail to regulate signaling of the Q61H mutant.

ACAGT-007a, an ERK MAPK Signaling Modulator, in Combination with AKT Signaling Inhibition Induces Apoptosis in KRAS Mutant Pancreatic Cancer T3M4 and MIA-Pa-Ca-2 Cells

“…Three PDAC cell lines with different genetic backgrounds regarding KRAS mutations (MIA-Pa-Ca-2, T3M4, and PANC-1) were tested for sensitivity to GT-7 in vitro using a cell viability assay ( Figure 1 A). T3M4 cells harbor the KRAS Q61H mutation, which is found in about 5% of PDAC patients and the most prevalent mutation occurring at codon 61 of KRAS [ 12 ]. PANC-1 cells harbor the KRAS G12D mutation, which is most prevalent in PDAC.…”

RAS mutation patterns arise from tissue-specific responses to distinct oncogenic signaling

“…Generally speaking, oncogenic signaling is a product of the amplitude of the signal (quantitative signaling) and/or the effector pathway engaged (qualitative signaling). In terms of quantitative signaling, different mutations can exhibit different degrees of activation (GTP-loading) and/or different sensitivities to positive (Ras GTP exchange factors, RASGEFs) or negative (RAS GTPase activating proteins, RASGAPs) regulators (Gebregiworgis et al, 2021;Lu et al, 2016;Muñoz-Maldonado et al, 2019;Simanshu et al, 2017). Various methods to manipulate quantitative Kras signaling, such as through modulating recombination rates (Singh et al, 2020), homozygous expression of the mutant allele (Burgess et al, 2017), changing codon usage to increase translation (Pershing et al, 2015), additional pharmacologic activation of the mitogen activated protein kinase (MAPK) pathway (Cicchini et al, 2017), and so forth (Li et al, 2018), all affect tumorigenesis.…”

“…The copyright holder for this preprint this version posted December 10, 2021. ; https://doi.org/10.1101/2021.12.10.472098 doi: bioRxiv preprint et al, 2019), akin to other substitutions at these two positions (Gebregiworgis et al, 2021;Smith et al, 2013). In those few cases in which the tumorigenic potential of the G12D and Q61R mutants have been directly compared in mice, tissue specific expression of Nras G12D or Kras G12D was less potent than their Q61R counterparts at inducing melanoma (Burd et al, 2014) or myeloproliferative neoplasm (Kong et al, 2016), respectively.…”

KRAS Q61H Mutation Confers Cancer Cells with Acquired Resistance to SHP2 Inhibition

“…Thus, it is necessary to elucidate detailed mechanisms for the different sensitivity of KRAS mutants to SHP2i. 1 Gebregiworgis et al reported that pancreatic ductal adenocarcinoma cells with KRAS Q61H mutation were insensitive to both allosteric and orthosteric SHP2i, which is a unique feature for Q61H mutant. 1 Q61H mutation was insensitive to SOSmediated nucleotide exchange as for the unstable KRAS-SOS complex.…”

“…A recent work published in Nature Communications revealed the underlying drug resistance mechanism of cancer cells harboring KRAS Q61H mutation to SHP2 inhibitors (SHP2i). 1 This work showed that KRAS Q61H mutation renders cancer cells resistant to SHP2i via decoupling KRAS from SHP2-mediated upstream nucleotide exchange factors for (guanine nucleotide exchange factor [GEF])/GTPase activating protein (GAP) regulation, providing new insights into treating cancers with KRAS Q61H mutations.…”