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TSC2 immunohistochemistry assay validation and analysis of HCC xenograft and primary tumors. (A) TSC2 immunohistochemistry (IHC) assay with HCC cell lines. (B) TSC2 IHC assay with HCC xenograft tumors. (C) TSC2 expression by IHC assay in HCC xenografts and their corresponding primary tumors.

Schematic illustration of MEKi-induced MAPK pathway feedback activation, SHP099 dose-dependent reduction of p-MEK induction by MEKi, and MEKi-induced p-AKT levels.

Race distribution of HCC patients in EVOLVE-1 trial. Percentage of Caucasian, Asian and other race in different groups of EVOLVE-1 patients (A) and TSC2 IHC H-score ranges (B).

Evaluation of the in vitro synergy in anti-proliferation and the MAPK pathway suppression of MEK and SHP2, PI3K, or RTK inhibitors.

Mechanisms of TSC2 loss in HCC cell lines and xenografts. (A) Taqman RT-PCR analysis of TSC1 and TSC2 mRNA levels in HCC cell lines. (B) Taqman RT-PCR analysis of MZB1, TSC1 and TSC2 mRNA levels in TSC2-null Li-7 cells treated with epigenetic inhibitors. (C) Taqman RT-PCR analysis and (D) immunoblot analysis of TSC2 G305V mutant in HEK293T cells.

Supplementary Table 4: List of cell lines evaluated for sensitivity to SHP099 (Tab 1) or an RTK-inhibitor (Tab 2) in 2D or 3D. Included is the lineage and the KRAS mutation status. Where data are blank, no viable data was available, or the cell line did not grow appropriately as a tumor spheroid.

Genetic characterization of 35 established HCC PTX models by targeted DNA sequencing (Excel file).

In vivo efficacy of SHP099 (100 mg/kg, daily) in the KYSE-520 esophageal cancer cell line model. Data are plotted as the treatment mean {plus minus} s.e.m (n=7) ( (B-I) In vivo efficacy data for cell line models represented in Fig. 3E. SHP099 and trametinib were orally administered at the doses, schedules and for the duration indicated. Data are plotted as the treatment mean {plus minus} s.e.m.

Supplementary Table 1. Quantification of phospho-protein levels in Figure 1B. Supplementary Table 2. Everolimus IC50 and growth inhibition at 1uM in HCC cell lines. Supplementary Table 3. Quantification of phospho-protein levels in Figure 2A.

FGFR1 was recently shown to be activated as part of a compensatory response to prolonged treatment with the MEK inhibitor trametinib in several KRAS-mutant lung and pancreatic cancer cell lines. We hypothesize that other receptor tyrosine kinases (RTK) are also feedback-activated in this context. Herein, we profile a large panel of KRAS-mutant cancer cell lines for the contribution of RTKs to the feedback activation of phospho-MEK following MEK inhibition, using an SHP2 inhibitor (SHP099) that blocks RAS activation mediated by multiple RTKs. We find that RTK-driven feedback activation widely exists in KRAS-mutant cancer cells, to a less extent in those harboring the G13D variant, and involves several RTKs, including EGFR, FGFR, and MET. We further demonstrate that this pathway feedback activation is mediated through mutant KRAS, at least for the G12C, G12D, and G12V variants, and wild-type KRAS can also contribute significantly to the feedback activation. Finally, SHP099 and MEK inhibitors exhibit combination benefits inhibiting KRAS-mutant cancer cell proliferation in vitro and in vivo. These findings provide a rationale for exploration of combining SHP2 and MAPK pathway inhibitors for treating KRAS-mutant cancers in the clinic.

mRNA levels (TPM, transcripts per million reads in RNAseq) of SHP2, RTKs, and their ligands in all cell lines tested.

Supplementary Material and Methods. File contains the following: Transcriptome sequencing and analysis, Soft agar assay, 2D and 3D Cell proliferation screen and compound characterization information.

TSC2 loss in HCC cell lines leads to mTOR activation. (A) Reverse Phase Protein Array (RPPA) analysis of nine HCC cell lines for TSC2 protein levels and phosphorylation levels of S6K1, 4E-BP1, S6 and AKT. (B) Immunoblot of TSC2 wild-type HuH-7 cells treated with inhibitors of PI3K, AKT or MEK. (C) p-S6K1(T389) immunoblot of TSC2-null HCC cell lines treated with varying concentrations of everolimus.

Quantification of p-MEK and tubulin levels and percentages of p-MEK reduction in the MEKi combination group normalized to tubulin in all cell lines tested.

Validation of HRAS/NRAS double knock-out clones and the contribution of mutant KRAS to the feedback activation in NCI-H358 and MIA PaCa-2.

A list of KRAS mutant cell lines in the study with lineages, zygosity determined by RNAseq, and percentages of p-MEK reduction by 5 micromolar SHP099 in the MEKi combination group.

Model of mTOR activation and everolimus sensitivity caused by TSC2 loss.

Changes in phospho-SHP2 levels following MEKi treatment in studied KRAS mutant lines.

Evaluation of the in vivo combination benefit and the MAPK pathway suppression of MEK and SHP2 inhibitors in MIA PaCa-2 xenograft and a colon cancer PDX model.

CSF1R-driven SHP2-dependent MAPK signaling in GDM-1 cells and SHP2 dependency of the viability in M-CSF-stimulated monocytes in the T cell co-culture assay, and the in vivo combination benefit in suppressing tumor associated macrophage by anti-PD-1 antibody and TNO155 in MC38 tumors.

Supplementary Figure Legend

The synergy in the MAPK pathway suppression and anti-proliferation effect by KRASG12C inhibitor and TNO155.

Purpose:The selective MET inhibitor capmatinib is being investigated in multiple clinical trials, both as a single agent and in combination. Here, we describe the preclinical data of capmatinib, which supported the clinical biomarker strategy for rational patient selection.Experimental Design:The selectivity and cellular activity of capmatinib were assessed in large cellular screening panels. Antitumor efficacy was quantified in a large set of cell line– or patient-derived xenograft models, testing single-agent or combination treatment depending on the genomic profile of the respective models.Results:Capmatinib was found to be highly selective for MET over other kinases. It was active against cancer models that are characterized by MET amplification, marked MET overexpression, MET exon 14 skipping mutations, or MET activation via expression of the ligand hepatocyte growth factor (HGF). In cancer models where MET is the dominant oncogenic driver, anticancer activity could be further enhanced by combination treatments, for example, by the addition of apoptosis-inducing BH3 mimetics. The combinations of capmatinib and other kinase inhibitors resulted in enhanced anticancer activity against models where MET activation co-occurred with other oncogenic drivers, for example EGFR activating mutations.Conclusions:Activity of capmatinib in preclinical models is associated with a small number of plausible genomic features. The low fraction of cancer models that respond to capmatinib as a single agent suggests that the implementation of patient selection strategies based on these biomarkers is critical for clinical development. Capmatinib is also a rational combination partner for other kinase inhibitors to combat MET-driven resistance.

Identification of the feedback activated RTK and the synergy in anti-proliferation effect by the combination of respective RTK inhibitors and dabrafenib plus trametinib in RKO and MDST8 cells.

Purpose:SHP2 inhibitors offer an appealing and novel approach to inhibit receptor tyrosine kinase (RTK) signaling, which is the oncogenic driver in many tumors or is frequently feedback activated in response to targeted therapies including RTK inhibitors and MAPK inhibitors. We seek to evaluate the efficacy and synergistic mechanisms of combinations with a novel SHP2 inhibitor, TNO155, to inform their clinical development.Experimental Design:The combinations of TNO155 with EGFR inhibitors (EGFRi), BRAFi, KRASG12Ci, CDK4/6i, and anti–programmed cell death-1 (PD-1) antibody were tested in appropriate cancer models in vitro and in vivo, and their effects on downstream signaling were examined.Results:In EGFR-mutant lung cancer models, combination benefit of TNO155 and the EGFRi nazartinib was observed, coincident with sustained ERK inhibition. In BRAFV600E colorectal cancer models, TNO155 synergized with BRAF plus MEK inhibitors by blocking ERK feedback activation by different RTKs. In KRASG12C cancer cells, TNO155 effectively blocked the feedback activation of wild-type KRAS or other RAS isoforms induced by KRASG12Ci and greatly enhanced efficacy. In addition, TNO155 and the CDK4/6 inhibitor ribociclib showed combination benefit in a large panel of lung and colorectal cancer patient–derived xenografts, including those with KRAS mutations. Finally, TNO155 effectively inhibited RAS activation by colony-stimulating factor 1 receptor, which is critical for the maturation of immunosuppressive tumor-associated macrophages, and showed combination activity with anti–PD-1 antibody.Conclusions:Our findings suggest TNO155 is an effective agent for blocking both tumor-promoting and immune-suppressive RTK signaling in RTK- and MAPK-driven cancers and their tumor microenvironment. Our data provide the rationale for evaluating these combinations clinically.

The activity of nazartinib, TNO155, and their combination in EGFR mutant NSCLC cell lines.

Supplementary text and figures Supplementary Figure 1 A, visualization of the "inflection point" (or EC50) and "Amax" parameters that are shown in Fig. 2A. B, HGF mRNA expression (by RNA-seq) vs HGF protein in culture supernatant for 76 cancer cell lines. Cell lines with high HGF mRNA expression generally led to increased protein levels in supernatant. U87-MG and IM95 are labeled, because in vivo efficacy data are presented for those models. U87-MG shows a remarkably high level of HGF protein secretion despite relatively low HGF mRNA. C, labeled cell lines scored as hits with at least 2 out of 4 MET inhibitors, each screened twice across a subset of the CCLE. Hits were defined as Amax {less than or equal to} â^'25% for all compounds, and inflection point {less than or equal to} 100 nmol/L for capmatinib, {less than or equal to} 1 ï�­mol/L for crizotinib and JNJ-38877605, and {less than or equal to} 500 nmol/L for PF-4217903. The upper panel shows MET vs HGF mRNA expression, while the lower panel shows MET expression vs MET copy number for the same cell lines. Three regions that among themselves contain all hits (amplified, overexpression, autocrine) were defined such that the hit with the lowest value for the respective expression or copy number value sets the cut-off. Number of hits compared to total number of cell lines in the respective regions are indicated in brackets. Colors as in Figure 2. D, Time course of MET phosphorylation after a 5 minute pulse treatment with 100 ng/mL recombinant HGF in 2 cell lines. NCI-H596 cells bear a MET exon14 skipping mutation while A549 cells do not. Supplementary Figure 2 A, MET dependency (x axis) vs MET gene copy number (y axis), downloaded from https://depmap.org. MET gene dependency was estimated by applying the DEMETER2 model to a combination of 3 large-scale RNAi screens (Broad Achilles, Novartis DRIVE, Marcotte et al.) (7). B, MET dependency (x axis) vs HGF mRNA expression by RNA-seq (y axis), downloaded from https://depmap.org. MET gene dependency was determined from pooled CRISPR screening data (Avana 1.0 library, Broad Institute) applying the CERES algorithm (8,9). Supplementary Figure 3 A, potency comparison of several clinical MET inhibitors in cellular proliferation assays with EBC-1 cells. Representative dose-response curves are shown on the left, numerical inflection point values (mean {plus minus} standard deviation, n = 3) are displayed on the right. B, MET mRNA expression measured by Affymetrix human genome U133 Plus 2.0 arrays (x axis) or RNA-seq (y axis) in 67 lung cancer PDX models (Supplementary Table 3). Identifiers of the 3 models with highest expression are indicated. C, same models as in B, but displaying MET mRNA by RNA-seq (x axis) vs MET copy number by Affymetrix SNP 6.0 array (y axis). D, data as in Fig. 3B but showing individual tumor volumes under treatment with capmatinib. E, mouse body weights corresponding to the experiment shown in Fig. 3B. F, data as in Fig. 3C but phospho- MET and total MET values from multi-spot ELISA shown separately. G, repeat of capmatinib efficacy study with lung PDX tumors bearing a MET exon 14 skipping mutation (model LU5381) as in Fig. 3D, but longer treatment duration. An average regression of ~60% was observed on day 12. A vehicle control was not repeated in this study. H, antitumor efficacy of capmatinib (dosed as indicated) against xenografts of the gastric cancer cell line IM95, which expresses HGF. Supplementary Figure 4 A, Loewe excess for data shown in Fig. 4C (upper panel), and % inhibition as well as Loewe excess for a combination matrix of capmatinib and the selective BCL2 inhibitor venetoclax (lower panel), in the cell line NCI-H1993. Percent dead cells were quantified by dual imaging with propidium iodide (PI) and Hoechst 33342. B, Percent dead cells by PI/Hoechst (upper panel) and Loewe excess (lower panel) for EBC-1 cells treated as in Fig. 4C and Supplementary Fig. 4A. C, Loewe excess for data shown in Fig. 4D, cell lines as indicated. Here, data are based on a CellTiter-Glo readout with quantification of seeded cells at time of compound addition ("growth inhibition" calculation). Loewe excess also refers to the "growth inhibition" data. D, treatment of EBC-1 cells with the indicated dose matrix of capmatinib and erlotinib. Experimental setup and analysis as in Fig. 4D (docetaxel combination). Supplementary Figure 5 A, HCC827 or HCC827 GR lung cancer cells were exposed to gefitinib, capmatinib, or combinations in a fixed ratio for 72 hours before measuring cell viability using a resazurin assay. The x axis label corresponds to gefitinib concentrations, while capmatinib was used at 10-fold lower concentrations due to its higher potency. In combination, gefitinib and capmatinib were mixed at a ratio of 10:1. B, HCC827 or NCI-H3255 cells were treated with a dilution series of gefitinib in the presence or absence of 50 ng/mL recombinant HGF. Cell viability was measured after 96 hours (HCC827) or 72 hours (NCIH3255) using a resazurin assay. The initial amount of viable cells was quantified at the time of compound addition (dashed line), and cell growth on the y axis is expressed as a multiple of this value. C, lysates of the lung cancer PDX model X-1787, either treated with vehicle or crizotinib, were incubated on a phospho-RTK array. Phospho-MET is clearly detectable in vehicle-treated lysate, suggesting that the high MET mRNA expression in this model leads to MET protein expression and activation. D, anti-tumor efficacy of crizotinib against X-1787 PDX tumors, characterized by presence of EML4-ALK and high MET expression. N = 4 per arm. E, RKO cells (BRAF V600E-mutant colorectal cancer cells secreting HGF) were exposed to capmatinib and fixed ratios of dabrafenib and trametinib in a dose matrix as indicated. After 3 days, viable cells were quantified by CellTiter-Glo. Inhibition is quantified in 2 different ways, without or with regard of the initial amount of viable cells at the time of compound addition (left and middle panel, respectively). Calculations are explained in detail in Materials and Methods. The right panel shows the Loewe excess for "% inhibition."

Supplementary Table 1. IC50 values for capmatinib obtained in BaF3 TRP-MET cells and mutant variants as indicated after 3-day proliferation assays with a resazurin readout. MET kinase domain mutations were either generated by site-directed mutagenesis or obtain by random mutagenesis and selection with another selective MET inhibitor (5). Supplementary Table 2. Numerical data that are graphically represented in Figure 2. Supplementary Table 3. Combined data from CCLE screens with 4 MET inhibitors (capmatinib, crizotinib, JNJ- 38877605, and PF-4217903). Related to Supplementary Fig. 1C. Supplementary Table 4. MET genomics data and additional model information for a collection of lung cancer PDX models downloaded from https://compendium.criver.com/. The Excel table is filtered down to those 66 models with complete data for MET mRNA (both Affymetrix and RNA-seq), MET mutations, and MET gene copy number, but other lung cancer models with partial data are also contained within the table. The 3 models that were used for capmatinib in vivo efficacy studies are highlighted in yellow.

Purpose: SHP2 inhibitors offer an appealing and novel approach to inhibit receptor tyrosine kinase (RTK) signaling, which is the oncogenic driver in many tumors or is frequently feedback activated in response to targeted therapies including RTK inhibitors and MAPK inhibitors. We seek to evaluate the efficacy and synergistic mechanisms of combinations with a novel SHP2 inhibitor, TNO155, to inform their clinical development. Experimental Design: The combinations of TNO155 with EGFR inhibitors (EGFRi), BRAFi, KRASG12Ci, CDK4/6i, and anti–programmed cell death-1 (PD-1) antibody were tested in appropriate cancer models in vitro and in vivo, and their effects on downstream signaling were examined. Results: In EGFR-mutant lung cancer models, combination benefit of TNO155 and the EGFRi nazartinib was observed, coincident with sustained ERK inhibition. In BRAFV600E colorectal cancer models, TNO155 synergized with BRAF plus MEK inhibitors by blocking ERK feedback activation by different RTKs. In KRASG12C cancer cells, TNO155 effectively blocked the feedback activation of wild-type KRAS or other RAS isoforms induced by KRASG12Ci and greatly enhanced efficacy. In addition, TNO155 and the CDK4/6 inhibitor ribociclib showed combination benefit in a large panel of lung and colorectal cancer patient–derived xenografts, including those with KRAS mutations. Finally, TNO155 effectively inhibited RAS activation by colony-stimulating factor 1 receptor, which is critical for the maturation of immunosuppressive tumor-associated macrophages, and showed combination activity with anti–PD-1 antibody. Conclusions: Our findings suggest TNO155 is an effective agent for blocking both tumor-promoting and immune-suppressive RTK signaling in RTK- and MAPK-driven cancers and their tumor microenvironment. Our data provide the rationale for evaluating these combinations clinically.

Ewing sarcoma (ES) is a malignant pediatric bone and soft tissue tumor. Patients with metastatic ES have a dismal outcome which has not been improved in decades. The major challenge in the treatment of metastatic ES is the lack of specific targets and rational combinatorial therapy. We recently found that protein phosphatase 1 regulatory subunit 1A (PPP1R1A) is specifically highly expressed in ES and promotes tumor growth and metastasis in ES. In the current investigation, we show that PPP1R1A regulates ES cell cycle progression in G1/S phase by down-regulating cell cycle inhibitors p21Cip1 and p27Kip1, which leads to retinoblastoma (Rb) protein hyperphosphorylation. In addition, we show that PPP1R1A promotes normal transcription of histone genes during cell cycle progression. Importantly, we demonstrate a synergistic/additive effect of the combinatorial therapy of PPP1R1A and insulin-like growth factor 1 receptor (IGF-1R) inhibition on decreasing ES cell proliferation and migration in vitro and limiting xenograft tumor growth and metastasis in vivo. Taken together, our findings suggest a role of PPP1R1A as an ES specific cell cycle modulator and that simultaneous targeting of PPP1R1A and IGF-1R pathways is a promising specific and effective strategy to treat both primary and metastatic ES.

SHP2 mediates RAS activation downstream of multiple receptor tyrosine kinases (RTKs) and cancer cell lines dependent on RTKs are in general dependent on SHP2. Profiling of the allosteric SHP2 inhibitor SHP099 across cancer cell lines harboring various RTK dependencies reveals that FGFR-dependent cells are often insensitive to SHP099 when compared to EGFR-dependent cells. We find that FGFR-driven cells depend on SHP2 but exhibit resistance to SHP2 inhibitors in vitro and in vivo. Treatment of such models with SHP2 inhibitors results in an initial decrease in phosphorylated ERK1/2 (p-ERK) levels, however p-ERK levels rapidly rebound within two hours. This p-ERK rebound is blocked by FGFR inhibitors or high doses of SHP2 inhibitors. Mechanistically, compared with EGFR-driven cells, FGFR-driven cells tend to express high levels of RTK negative regulators such as the SPRY family proteins, which are rapidly downregulated upon ERK inhibition. Moreover, over-expression of SPRY4 in FGFR-driven cells prevents MAPK pathway reactivation and sensitizes them to SHP2 inhibitors. We also identified two novel combination approaches to enhance the efficacy of SHP2 inhibitors, either with a distinct site 2 allosteric SHP2 inhibitor or with a RAS-SOS1 interaction inhibitor. Our findings suggest the rapid FGFR feedback activation following initial pathway inhibition by SHP2 inhibitors may promote the open conformation of SHP2 and lead to resistance to SHP2 inhibitors. These findings may assist to refine patient selection and predict resistance mechanisms in the clinical development of SHP2 inhibitors and to suggest strategies for discovering SHP2 inhibitors that are more effective against upstream feedback activation.

KRAS, an oncogene mutated in nearly one third of human cancers, remains a pharmacologic challenge for direct inhibition except for recent advances in selective inhibitors targeting the G12C variant. Here, we report that selective inhibition of the protein tyrosine phosphatase, SHP2, can impair the proliferation of KRAS-mutant cancer cells in vitro and in vivo using cell line xenografts and primary human tumors. In vitro, sensitivity of KRAS-mutant cells toward the allosteric SHP2 inhibitor, SHP099, is not apparent when cells are grown on plastic in 2D monolayer, but is revealed when cells are grown as 3D multicellular spheroids. This antitumor activity is also observed in vivo in mouse models. Interrogation of the MAPK pathway in SHP099-treated KRAS-mutant cancer models demonstrated similar modulation of p-ERK and DUSP6 transcripts in 2D, 3D, and in vivo, suggesting a MAPK pathway–dependent mechanism and possible non-MAPK pathway–dependent mechanisms in tumor cells or tumor microenvironment for the in vivo efficacy. For the KRASG12C MIAPaCa-2 model, we demonstrate that the efficacy is cancer cell intrinsic as there is minimal antiangiogenic activity by SHP099, and the effects of SHP099 is recapitulated by genetic depletion of SHP2 in cancer cells. Furthermore, we demonstrate that SHP099 efficacy in KRAS-mutant models can be recapitulated with RTK inhibitors, suggesting RTK activity is responsible for the SHP2 activation. Taken together, these data reveal that many KRAS-mutant cancers depend on upstream signaling from RTK and SHP2, and provide a new therapeutic framework for treating KRAS-mutant cancers with SHP2 inhibitors.

FGFR1 was recently shown to be activated as part of a compensatory response to prolonged treatment with the MEK inhibitor trametinib in several KRAS-mutant lung and pancreatic cancer cell lines. We hypothesize that other receptor tyrosine kinases (RTK) are also feedback-activated in this context. Herein, we profile a large panel of KRAS-mutant cancer cell lines for the contribution of RTKs to the feedback activation of phospho-MEK following MEK inhibition, using an SHP2 inhibitor (SHP099) that blocks RAS activation mediated by multiple RTKs. We find that RTK-driven feedback activation widely exists in KRAS-mutant cancer cells, to a less extent in those harboring the G13D variant, and involves several RTKs, including EGFR, FGFR, and MET. We further demonstrate that this pathway feedback activation is mediated through mutant KRAS, at least for the G12C, G12D, and G12V variants, and wild-type KRAS can also contribute significantly to the feedback activation. Finally, SHP099 and MEK inhibitors exhibit combination benefits inhibiting KRAS-mutant cancer cell proliferation in vitro and in vivo. These findings provide a rationale for exploration of combining SHP2 and MAPK pathway inhibitors for treating KRAS-mutant cancers in the clinic.

FGFR1 was recently shown to be activated as part of a compensatory response to prolonged treatment with MEK inhibitor trametinib in several KRAS-mutant lung and pancreatic cancer cell lines. We hypothesize that other receptor tyrosine kinases (RTKs) are also feedback activated in this context. Herein, we profile a large panel of KRAS-mutant cancer cell lines for the contribution of RTKs to the feedback activation of phospho-MEK following MEK inhibition, using a SHP2 inhibitor (SHP099) that blocks RAS activation mediated by multiple RTKs. We find that RTK-driven feedback activation widely exists in KRAS mutant cancer cells and involves several RTKs including EGFR, FGFR, and MET. We further demonstrate this pathway feedback activation is mediated through mutant KRAS. Finally, SHP099 and MEK inhibitors exhibit combination benefits inhibiting KRAS mutant cancer cell proliferation in vitro and in vivo. These findings provide a rationale for exploration of combining SHP2 and MAPK pathway inhibitors for treating KRAS-mutant cancers in the clinic. Citation Format: Hengyu Lu, Chen Liu, Roberto Velazquez, Hongyun Wang, Lukas M. Dunkl, Malika Kazic-Legueux, Anne Haberkorn, Eric Billy, Eusebio Manchado, Saskia M. Brachmann, Susan Moody, Jeffrey A. Engelman, Peter S. Hammerman, Giordano Caponigro, Morvarid Mohseni, Huai-Xiang Hao. SHP2 inhibition overcomes RTK-mediated pathway reactivation in KRAS-mutant tumors treated with MEK inhibitors [abstract]. In: Proceedings of the AACR Special Conference on Targeting RAS-Driven Cancers; 2018 Dec 9-12; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2020;18(5_Suppl):Abstract nr A44.

SHP2 is a cytoplasmic protein tyrosine phosphatase encoded by the PTPN11 gene and is involved in cell proliferation, differentiation, and survival. Recently, we reported an allosteric mechanism of inhibition that stabilizes the auto-inhibited conformation of SHP2. SHP099 (1) was identified and characterized as a moderately potent, orally bioavailable, allosteric small molecule inhibitor, which binds to a tunnel-like pocket formed by the confluence of three domains of SHP2. In this report, we describe further screening strategies that enabled the identification of a second, distinct small molecule allosteric site. SHP244 (2) was identified as a weak inhibitor of SHP2 with modest thermal stabilization of the enzyme. X-ray crystallography revealed that 2 binds and stabilizes the inactive, closed conformation of SHP2, at a distinct, previously unexplored binding site-a cleft formed at the interface of the N-terminal SH2 and PTP domains. Derivatization of 2 using structure-based design resulted in an increase in SHP2 thermal stabilization, biochemical inhibition, and subsequent MAPK pathway modulation. Downregulation of DUSP6 mRNA, a downstream MAPK pathway marker, was observed in KYSE-520 cancer cells. Remarkably, simultaneous occupation of both allosteric sites by 1 and 2 was possible, as characterized by cooperative biochemical inhibition experiments and X-ray crystallography. Combining an allosteric site 1 inhibitor with an allosteric site 2 inhibitor led to enhanced pharmacological pathway inhibition in cells. This work illustrates a rare example of dual allosteric targeted protein inhibition, demonstrates screening methodology and tactics to identify allosteric inhibitors, and enables further interrogation of SHP2 in cancer and related pathologies.

Additional file 1: Figure S1. INC280 alone is sufficient in inhibiting MKN45 proliferation. (A) INC280 (0.1, 1 µM) treatment for 72 hrs potently inhibited MKN45 proliferation as measured by the CellTiter-Glo assay. Further combination with ATM inhibitor Ku60019 did not improve efficacy. Data represents for Mean ± SD. Vertical bar represents the standard deviation. (B) INC280 mediated ATM signaling pathway activity in MKN45 cells.

Research highlights ► Mouse PDX1 Ser-269 is phosphorylated in pancreatic islets of Langerhans and beta cells. ► High glucose concentration decreases the degree of phosphorylation on PDX1 Ser-269, as assessed by a phospho-specific anti-phospho-Ser269 antibody. ► HIPK2 is a potential kinase for PDX1 Ser-269. ► Phosphorylation at Ser-269 affects the subnuclear distribution of PDX1., Pancreatic and duodenal homeobox 1 (PDX1) regulates pancreatic development and mature β-cell function. We demonstrate by mass spectrometry that serine residue at position 269 in the C-terminal domain of PDX1 is phosphorylated in β-cells. Besides we show that the degree of phosphorylation, assessed with a phospho-Ser-269-specific antibody, is decreased by elevated glucose concentrations in both MIN6 β-cells and primary mouse pancreatic islets. Homeodomain interacting protein kinase 2 (HIPK2) phosphorylates PDX1 in vitro; phosphate incorporation substantially decreases in PDX1 S269A mutant. Silencing of HIPK2 led to a 51 ± 0.2% decrease in Ser-269 phosphorylation in MIN6 β-cells. Mutation of Ser-269 to phosphomimetic residue glutamic acid (S269E) or de-phosphomimetic residue alanine (S269A) exerted no effect on PDX1 half-life. Instead, PDX1 S269E mutant displayed abnormal changes in subnuclear localization in response to high glucose. Our results suggest that HIPK2-mediated phosphorylation of PDX1 at Ser-269 might be a regulatory mechanism connecting signals generated by changes in extracellular glucose concentration to downstream effectors via changes in subnuclear localization of PDX1, thereby influencing islet cell differentiation and function.

Metabolic disorders, such as diabetes and obesity, are fundamentally caused by cellular energy imbalance and dysregulation. Therefore, understanding the regulation of cellular fuel and energy metabolism is of great importance to develop effective therapies for metabolic disease. The cellular nutrient and energy sensors, AMPK and TOR, play a key role in maintaining cellular energy homeostasis. Like AMPK and TOR, PAS kinase (PASK) is also a nutrient responsive protein kinase. In yeast, PAS kinase phosphorylates the enzyme Ugp1 and thereby shifts glucose partitioning toward cell wall glucan synthesis at the expense of glycogen synthesis. Consistent with this function, yeast PAS kinase is activated by both cell integrity stress and growth in non-fermentative carbon sources. PASK is also important for proper regulation of glucose metabolism in mammals at both the hormonal and cellular level. In cultured pancreatic beta-cells, PASK is activated by elevated glucose concentrations and is required for glucose-stimulated transcription of the insulin gene. PASK knockdown in cultured myoblasts causes increased glucose oxidation and elevated cellular ATP levels. Mice lacking PASK exhibit increased metabolic rate and resistance to diet-induced obesity. Interestingly, PGC-1 expression and AMPK and TOR activity were not affected in PASK deficient mice, suggesting PASK may exert its metabolic effects through a new mechanism. We propose that PASK plays a significant role in nutrient sensing, metabolic regulation, and energy homeostasis, and is a potential therapeutic target for metabolic disease.

The metabolic syndrome, a complex set of phenotypes typically associated with obesity and diabetes, is an increasing threat to global public health. Fundamentally, the metabolic syndrome is caused by a failure to properly sense and respond to cellular metabolic cues. We studied the role of the cellular metabolic sensor PAS kinase (PASK) in the pathogenesis of metabolic disease by using PASK −/− mice. We identified tissue-specific metabolic phenotypes caused by PASK deletion consistent with its role as a metabolic sensor. Specifically, PASK −/− mice exhibited impaired glucose-stimulated insulin secretion in pancreatic β-cells, altered triglyceride storage in liver, and increased metabolic rate in skeletal muscle. Further, PASK deletion caused nearly complete protection from the deleterious effects of a high-fat diet including obesity and insulin resistance. We also demonstrate that these cellular effects, increased rate of oxidative metabolism and ATP production, occur in cultured cells. We therefore hypothesize that PASK acts in a cell-autonomous manner to maintain cellular energy homeostasis and is a potential therapeutic target for metabolic disease.

Tapping the Mitochondrial Proteome Mitochondria produce the energy that cells need to survive, function, and divide. A growing list of human disorders has been traced to defects in mitochondrial function. About 300 mammalian mitochondrial proteins are functionally uncharacterized, and Hao et al. (p. 1139 , published online 23 July) reasoned that the most highly conserved proteins within this group might provide insights into human disease. A combination of bioinformatics, yeast genetics, biochemistry, and human genetics was used to show that a previously uncharacterized mitochondrial protein (Sdh5) is required for the activity of respiratory complex II. Inactivating mutations in the human gene encoding SDH5 were found in individuals with hereditary paraganglioma, a rare neuroendocrine tumor. Thus, analysis of a mitochondrial protein in yeast has revealed a human tumor susceptibility gene.