Research ArticleCancer

The ERBB network facilitates KRAS-driven lung tumorigenesis

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Science Translational Medicine  20 Jun 2018:
Vol. 10, Issue 446, eaao2565
DOI: 10.1126/scitranslmed.aao2565
  • Fig. 1 ERBB activity is required for KRAS-driven lung tumor formation.

    (A) Expression of ERBB family RTKs in KM lung tumors harvested 6 weeks post-allele induction (PI), measured by RNA-sequencing (RNA-seq). Mean ± SD read counts in tumors from four mice are shown. (B) Expression of ERBB family ligands in KM lung tumors harvested 6 weeks PI, as per (A). (C) Immunoblots of lysates generated from 10 individual KM tumors, harvested 6 weeks PI, using the indicated antibodies. (D) Representative images of immunohistochemistry (IHC) for Ki67 and terminal deoxynucleotidyl transferase–mediated deoxyuridine triphosphate nick end labeling (TUNEL) staining of KM mice treated for 3 days with neratinib (80 mg/kg) (n = 3) or vehicle control (n = 3). Scale bars, 100 μm. (E) Quantification (mean ± SEM) of staining in five tumors from each mouse as per (D). Left panel shows % of tumor cells expressing Ki67; right panel shows % of TUNEL-positive tumor cells; vc, vehicle control. P values are from two-tailed t tests. (F) Immunoblots of three individual KM tumors from mice treated for 3 days with neratinib or vehicle control. (G) Representative hematoxylin and eosin (H&E) images from KM mice treated daily with neratinib (2 × 40 mg/kg) or erlotinib (2 × 50 mg/kg), commencing 2 weeks PI, and harvested at 6 weeks PI. Scale bar, 1 mm. (H) Quantification of tumor burden from (G). Box and whisker plots show median, interquartile, and 99% range of tumor area, expressed as a percentage of total lung tissue area, measured across >25 sections from each mouse. n = 5 vehicle control (vc), n = 4 erlotinib, and n = 3 neratinib. Analysis of variance (ANOVA) followed by Tukey test; ns, not significant.

  • Fig. 2 KM lung tumor progression is associated with increased ERK phosphorylation.

    (A) Images of H&E-stained (upper panels) and p-ERK–stained (lower panels) KM lung tumors harvested at 6 weeks PI illustrating histological changes associated with tumor progression: Left panels are representative of >95% of total tumor area at 6 weeks PI, whereas right panels represent 2 to 5% of total tumor area at 6 weeks PI. Scale bar, 50 μm. (B) p-ERK staining in KM tumors harvested at 6 weeks PI (top and middle panels) versus 5 months PI (bottom panel). Scale bars, 1 mm (top and bottom panels) and 200 μm (middle panel). (C) Detection of Hprt-lsl-IRFP expression in primary lung tumors (left) and a liver metastasis (right) in a KM mouse harvested 6 months PI. Scale bar, 5 mm. (D) Histological confirmation of liver metastasis stained by H&E. (E) IHC detection of SPC and p-ERK in the same metastasis as (D). Scale bars, 50 μm (D and E). Images are representative of six mice. (F) Halo quantification of p-ERK–positive cells in individual metastases, expressed as % of tumor cells.

  • Fig. 3 Expression of the ERBB network increases during progression from p-ERKlow to p-ERKhigh KM tumors.

    (A) Normalized expression of RAS genes in laser-capture microdissected p-ERKHigh KM tumor regions relative to p-ERKLow regions from tumors in the same mice (n = 4 mice), measured by RNA-seq. False discovery rate (FDR) shown for KRAS. (B) Mean and SEM RNA-seq reads of Ereg and Areg mRNA from p-ERKLow and p-ERKHigh KM tumor regions from four mice. Adjusted P values were calculated in R. (C) Serial sections of KM tumors stained by IHC for p-ERK (left panels) or by ISH for Ereg (middle panels) or Areg (right panels). Scale bars, 200 μm (upper panels) and 25 μm (lower panels). (D) Representative images of p-ERK (IHC) and Areg (ISH) expression in KM liver metastasis. Scale bar, 200 μm. Images are representative of four metastases with sufficient material. (E) Normalized expression of ERBB network genes showing mean fold increase (Δ) in expression in p-ERKHigh relative to p-ERKLow KM tumor regions from four mice as per (A). (F) Diagrammatic representation of up-regulated components of the ERBB-RAS-ERK pathway associated with KM tumor progression.

  • Fig. 4 A feed-forward ERBB signaling loop drives proliferation of KRAS-mutant human NSCLC cells.

    (A) Growth curves of three KRAS-mutant human NSCLC lines upon treatment with increasing doses of the EGFR-selective inhibitor erlotinib or the multi-ERBB inhibitor neratinib, measured by IncuCyte time-lapse video microscopy. Error bars show SD for technical triplicates. Data are representative of at least two independent experiments. (B) Lysates from KRAS-mutant NSCLC cells treated with increasing doses of neratinib, immunoblotted with the indicated antibodies. Asterisks, where present, indicate the correct band. (C) RAS immunoblots of RAF-coated bead precipitates from lysates of A549 cells treated with neratinib or vehicle control for 2 hours. Lysate input aliquots were also immunoblotted with the indicated antibodies. Right panel shows mean ± SEM for quantification of KRAS band intensities from three independent experiments (arbitrary units). P values are from two-tailed t tests. (D) Top 20 significantly modulated pathways associated with the transition to p-ERKHigh disease in the KM model, identified using Metacore GeneGO analysis of RNA-seq expression data. Segment size in the pie chart (left panel) reflects ranking of the pathways by FDR. Right panels show that 18 of the same pathways are modulated in each of the three KRAS-mutant human NSCLC lines after overnight treatment with neratinib (250 nM A549 and H2009; 25 nM H358). Numbers and pie segment sizes reflect ranking by FDR. (E) Expression of ERBB ligands in the indicated cells treated overnight with vehicle (black) or neratinib (red), measured by RNA-seq as per (D). Mean and SEM of biological triplicates shown. *P < 0.05, **P < 0.01, ***P < 0.0001, two-tailed t tests. EMT, epithelial-mesenchymal transition; IL-4, interleukin 4; NGF, nerve growth factor; TGF, transforming growth factor.

  • Fig. 5 ERBB blockade enhances MEK inhibitor–driven apoptosis in vitro and therapeutic impact in vivo.

    (A) Apoptosis induced in human NSCLC cells, measured 48 hours after treatment with the indicated doses of neratinib (nera) and/or trametinib (tram). Mean ± SEM of three independent experiments shown (ANOVA and Tukey test). (B) Clonogenic assay showing suppression of colony formation in A549 and H358 cells after 48 hours of treatment with the indicated inhibitors. Lower panels show quantification of colony area (% surface coverage) from five independent experiments. Significance was determined for drug combinations versus trametinib alone (ANOVA and Tukey test). (C) Lysates from the indicated cells treated for 24 hours with increasing doses of trametinib alone or the combination of trametinib and neratinib, immunoblotted with the indicated antibodies. Asterisks, where present, indicate the correct band. (D) Overall survival, measured from the first day of treatment, of tumor-bearing KM mice treated daily for 1 week (tan bar) with neratinib (80 mg/kg), trametinib (1 mg/kg), or the combination of both, then followed without further intervention. Treatment was commenced at 5 weeks PI. Cohorts shown are vehicle (n = 9), neratinib (n = 7), trametinib (n = 10), and trametinib + neratinib (n = 10). Log-rank hazard ratios (HR ± 95% confidence interval) and P values are shown for comparisons of trametinib + neratinib versus vehicle and trametinib + neratinib versus trametinib alone (dashed lines). (E) Lysates of individual tumors from mice treated with neratinib (80 mg/kg) and/or trametinib (1 mg/kg) for 3 days, blotted with the indicated antibodies.

Supplementary Materials

  • www.sciencetranslationalmedicine.org/cgi/content/full/10/446/eaao2565/DC1

    Materials and Methods

    Fig. S1. Characterization of KM lung tumors.

    Fig. S2. Comparison of KM phenotype induced by Ad-CMV-CRE and Ad-SPC-CRE.

    Fig. S3. Genomic alterations and expression of ERBB network genes in human KRAS-mutant LuAd.

    Fig. S4. Sensitivity of KRAS-mutant cell lines to ERBB blockade.

    Fig. S5. Longitudinal in vivo imaging of nascent lung tumors.

    Table S1. Summary of Metacore GeneGO pathway analysis.

    References (4247)

  • Supplementary Material for:

    The ERBB network facilitates KRAS-driven lung tumorigenesis

    Björn Kruspig, Tiziana Monteverde, Sarah Neidler, Andreas Hock, Emma Kerr, Colin Nixon, William Clark, Ann Hedley, Sarah Laing, Seth B. Coffelt, John Le Quesne, Craig Dick, Karen H. Vousden, Carla P. Martins, Daniel J. Murphy*

    *Corresponding author. Email: daniel.murphy{at}glasgow.ac.uk

    Published 20 June 2018, Sci. Transl. Med. 10, eaao2565 (2018)
    DOI: 10.1126/scitranslmed.aao2565

    This PDF file includes:

    • Materials and Methods
    • Fig. S1. Characterization of KM lung tumors.
    • Fig. S2. Comparison of KM phenotype induced by Ad-CMV-CRE and Ad-SPC-CRE.
    • Fig. S3. Genomic alterations and expression of ERBB network genes in human KRAS-mutant LuAd.
    • Fig. S4. Sensitivity of KRAS-mutant cell lines to ERBB blockade.
    • Fig. S5. Longitudinal in vivo imaging of nascent lung tumors.
    • Table S1. Summary of Metacore GeneGO pathway analysis.
    • References (4247)

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