Oncogenic RAS isoforms show a hierarchical requirement for the guanine nucleotide exchange factor SOS2 to mediate cell transformation

Sheffels, Erin; Sealover, Nancy E.; Wang, Chenyue; Kim, Do-Hyung; Vazirani, Isabella A.; Lee, Elizabeth; Terrell, Elizabeth M.; Morrison, Deborah K.; Luo, Ji; Kortum, Robert L.

doi:10.1126/scisignal.aar8371

Cited by 43 publications

(96 citation statements)

References 66 publications

(97 reference statements)

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“…The relevance of 3D culture systems extends to the identification of novel therapeutic targets and therapeutic combinations. We recently showed that SOS2 is specifically required for PI3K-dependent protection from anoikis in KRAS-mutated NSCLC cells (32) and SOS2 deletion synergizes with MEK inhibition to kill KRAS mutated cells only under 3D culture conditions (31). Here, we show marked synergy between vertical inhibition of EGFR and SOS1 in EGFR mutated cancer cells, but only under 3D culture conditions (Fig.…”

Section: Discussionsupporting

confidence: 60%

“…However, simultaneous inhibition of multiple RTKs with osimertinib may be required to eliminate oncogenic shift to alternative RTKs (8). Downstream 5 pharmacologic synergy, we demonstrate that SOS1 inhibition using BAY-293 synergizes with osimertinib only under 3D spheroid culture conditions, and in doing so add to the growing evidence that pharmacologic assessment of novel therapeutics designed to treat cancer must be performed under 3D culture conditions (27,31,(34)(35)(36). By assessing the pharmacologic landscape of EGFR/RAS pathway inhibitors, we demonstrate that inhibition of proximal signaling is required to synergize with osimertinib, and that combined EGFR and SOS1 inhibition synergizes to inhibit RAS effector signaling in 3D culture.…”

Section: Introductionsupporting

confidence: 52%

“…sgRNA studies. A non-targeting (NT) single guide RNA (sgRNA), a SOS2-targeted sgRNA (31), and 8 potential SOS1-targeted sgRNAs previously used to target SOS1 in a genome-wide CRISPR screen (37) were each cloned into pLentiCRISPRv2 as previously described (64). SOS1-2 was chosen as the SOS1 sgRNA for the study.…”

Section: Methodsmentioning

confidence: 99%

“…To determine whether SOS1 or SOS2 were required for 2D anchorage-dependent proliferation or 3D spheroid growth in EGFR-mutated NSCLC cells, SOS1 ((37) and Fig. S1) or SOS2 (31) were deleted in pooled HCC827 and H1975 cells, and both proliferation and spheroid growth were assessed versus NT controls ( Fig. 1B and C).…”

Section: Sos1 Deletion Inhibits Transformation In Egfr-mutated Nsclc mentioning

confidence: 99%

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Marked Synergy by Vertical Inhibition of EGFR signaling in NSCLC Spheroids: SOS1 as a therapeutic target in EGFR-mutated cancer

Theard

Sheffels

Sealover

et al. 2020

Preprint

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Drug treatment of 3D cancer spheroids more accurately reflects in vivo therapeutic responses compared to adherent culture studies. In EGFR-mutated lung adenocarcinoma, EGFR-TKIs show enhanced efficacy in spheroid cultures. Simultaneous inhibition of multiple parallel RTKs further enhances EGFR-TKI effectiveness. We show that the common RTK signaling intermediate SOS1 was required for 3D spheroid growth of EGFR-mutated NSCLC cells. Using two distinct measures of pharmacologic synergy, we demonstrated that SOS1 inhibition strongly synergized with EGFR-TKI treatment only in 3D spheroid cultures. Combined EGFR-and SOS1-inhibition markedly inhibited Raf/MEK/ERK and PI3K/AKT signaling. Finally, broad assessment of the pharmacologic landscape of drug-drug interactions downstream of mutated EGFR revealed synergy when combining an EGFR-TKI with inhibitors of proximal signaling intermediates SOS1 and SHP2, but not inhibitors of downstream RAS effector pathways. These data indicate that vertical inhibition of proximal EGFR signaling should be pursued as a potential therapy to treat EGFR-mutated tumors.of RAS, co-targeting intermediates of the RAF/MEK/ERK and PI3K/AKT pathways enhances of osimertinib effectiveness, however, signaling through the uninhibited effector pathway may drive resistance (17)(18)(19)(20). Thus, it may be important for therapeutic combinations including osimertinib to stifle all downstream RTK/RAS signaling to be effective.Recent studies suggest that pharmacologic assessments of targeted therapeutics should be performed under 3D culture conditions rather than in 2D adherent cultures (21,22). 3D spheroids show altered growth characteristics, changes in cell surface proteins, altered metabolism, changes in activation of signaling pathways or altered responses to targeted pathway inhibitors, and are more resistant to drug-induced apoptosis compared to 2D adherent cultures signaling (23-26). These differences may be particularly relevant in EGFR-mutated NSCLC. EGFR-mutated cells show differential RTK expression and phosphorylation in 3D versus 2Dconditions (27). Further, EGFR-mutated cells respond more robustly to first-generation EGFR-TKIs in 3D cultures, and these responses more closely resemble responses seen in vivo (28).These data highlight the need for pharmacologic assessment of therapeutics designed to treat EGFR-mutated NSCLC under 3D culture conditions. The ubiquitously expressed RasGEFs (guanine nucleotide exchange factors) SOS1 and SOS2 (son of sevenless 1 and 2) are common signaling intermediates of RTK-mediated RAS activation. Although not initially considered as drug targets because of the low oncogenic potential of SOS (29), there has been renewed interest in SOS proteins as therapeutic targets for cancer treatment. We and others have shown that SOS1 and SOS2 may be important therapeutic targets in KRAS-mutated cancer cells (30-32), and a specific SOS1 inhibitor (BAY-293) has recently been identified (33). Here, we investigate SOS1 and SOS2 as potential therapeutic targets in EGFR-mutated l...

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Section: Discussionsupporting

confidence: 60%

Section: Introductionsupporting

confidence: 52%

Section: Methodsmentioning

confidence: 99%

Section: Sos1 Deletion Inhibits Transformation In Egfr-mutated Nsclc mentioning

confidence: 99%

See 2 more Smart Citations

Marked Synergy by Vertical Inhibition of EGFR signaling in NSCLC Spheroids: SOS1 as a therapeutic target in EGFR-mutated cancer

Theard

Sheffels

Sealover

et al. 2020

Preprint

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“…Decreased affinity for the RAS-GAP NF1 (II) by the G13D mutant protein enables GAP-and EGFR-dependent regulation of wild-type RAS, thereby retaining sensitivity to EGFR inhibitors in KRAS G13D mutant cells. Sheffels et al (29) identified a role for the RAS-GEF SOS2 (III) in promoting WT HRAS activation of AKT to support MT KRAS-induced transformation of mouse fibroblasts in 3D growth culture conditions. degradation of RAS or release of nucleotide but instead locally altered RAS SWI structure that impaired both SOS1 and RAF effector binding.…”

Section: Direct Ras Targetingmentioning

confidence: 99%

RAS, wanted dead or alive: Advances in targeting RAS mutant cancers

Stalnecker

Der

2020

Sci. Signal.

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Oncogenic RAS proteins, which are mutated in approximately 24% of all human cancers, have earned a well-deserved reputation as being “undruggable.” However, several studies have challenged that reputation. With the first small molecules that directly target one oncogenic RAS mutant (G12C) undergoing clinical evaluation, there have been substantial advances in finding anti-RAS therapeutic strategies. Furthermore, new insights have come from the growing appreciation that neither all RAS proteins (HRAS, NRAS, and KRAS4A/KRAS4B) nor all oncogenic RAS mutations (such as at residues Gly12, Gly13, and Gln61) have the same impact on RAS signaling and function. The role of the nonmutated, wild-type RAS proteins in the context of mutant RAS is increasingly considered to be targetable, with reports of strategies that directly disrupt either the RAS interaction with activating guanine nucleotide exchange factors (GEFs) or receptor tyrosine kinase–mediated and GEF-dependent RAS activation (such as by targeting the scaffolding phosphatase SHP2). Last, the development of agents that target downstream effectors of RAS signaling has advanced substantially. In this review, we highlight some important trends in the targeting of RAS proteins in cancer.

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SOS2 modulates the threshold of EGFR signaling to regulate osimertinib efficacy and resistance in lung adenocarcinoma

Theard,

Linke,

Sealover

et al. 2024

Molecular Oncology

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Son of sevenless 1 and 2 (SOS1 and SOS2) are RAS guanine nucleotide exchange factors (RasGEFs) that mediate physiologic and pathologic receptor tyrosine kinase (RTK)‐dependent RAS activation. Here, we show that SOS2 modulates the threshold of epidermal growth factor receptor (EGFR) signaling to regulate the efficacy of and resistance to the EGFR tyrosine kinase inhibitor (EGFR‐TKI) osimertinib in lung adenocarcinoma (LUAD). SOS2 deletion (SOS2KO) sensitized EGFR‐mutated cells to perturbations in EGFR signaling caused by reduced serum and/or osimertinib treatment to inhibit phosphatidylinositol 3‐kinase (PI3K)/AKT pathway activation, oncogenic transformation, and survival. Bypassing RTK reactivation of PI3K/AKT signaling represents a common resistance mechanism to EGFR‐TKIs; SOS2KO reduced PI3K/AKT reactivation to limit osimertinib resistance. In a forced HGF/MET‐driven bypass model, SOS2KO inhibited hepatocyte growth factor (HGF)‐stimulated PI3K signaling to block HGF‐driven osimertinib resistance. Using a long‐term in situ resistance assay, most osimertinib‐resistant cultures exhibited a hybrid epithelial/mesenchymal phenotype associated with reactivated RTK/AKT signaling. In contrast, RTK/AKT‐dependent osimertinib resistance was markedly reduced by SOS2 deletion; the few SOS2KO cultures that became osimertinib resistant primarily underwent non‐RTK‐dependent epithelial–mesenchymal transition (EMT). Since bypassing RTK reactivation and/or tertiary EGFR mutations represent most osimertinib‐resistant cancers, these data suggest that targeting proximal RTK signaling, here exemplified by SOS2 deletion, has the potential to delay the development osimertinib resistance and enhance overall clinical responses for patients with EGFR‐mutated LUAD.

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Oncogenic RAS isoforms show a hierarchical requirement for the guanine nucleotide exchange factor SOS2 to mediate cell transformation

Cited by 43 publications

References 66 publications

Marked Synergy by Vertical Inhibition of EGFR signaling in NSCLC Spheroids: SOS1 as a therapeutic target in EGFR-mutated cancer

Marked Synergy by Vertical Inhibition of EGFR signaling in NSCLC Spheroids: SOS1 as a therapeutic target in EGFR-mutated cancer

RAS, wanted dead or alive: Advances in targeting RAS mutant cancers

SOS2 modulates the threshold of EGFR signaling to regulate osimertinib efficacy and resistance in lung adenocarcinoma

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