Unknown,Transcriptomics,Genomics,Proteomics

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Quinacrine Overcomes Resistance to Erlotinib by Inhibiting FACT, Nuclear Factor-kappa B and Cell Cycle Progression in Non-Small Cell Lung Cancer

ABSTRACT: Erlotinib is a tyrosine kinase inhibitor (TKI) that is approved as a second-line monotherapy in patients with advanced non-small cell lung cancer (NSCLC). In these patients, erlotinib prolongs survival but its benefit remains modest since many tumors express wild-type EGF receptor (wtEGFR) lacking a TKI-sensitizing mutation, develop a second-site EGFR mutation, e.g., EGFR-L858R/T790M, or activate an alternate receptor tyrosine kinase, e.g., through MET amplification. To test potential drug combinations that could improve the efficacy of erlotinib, we combined erlotinib with quinacrine, which inhibits the FACT (facilitates chromatin transcription) complex that is required for nuclear factor-M-NM-:B (NF-M-NM-:B) transcriptional activity. In A549 (wtEGFR), H1975 (EGFR-L858R/T790M) and H1993 (MET amplification) NSCLC cells, the combination of erlotinib and quinacrine was highly synergistic, as quantified by Chou-Talalay combination indices. The combination inhibited colony formation, induced cell cycle arrest and apoptosis, and slowed xenograft tumor growth. Quinacrine decreased the level of active FACT subunit SSRP1 and suppressed NF-M-NM-:B-dependent luciferase activity. Knockdown of SSRP1 decreased cell growth and sensitized cells to erlotinib. Transcriptomic profiling showed that quinacrine, alone or in combination with erlotinib, significantly affected cell cycle-related genes that contain binding sites for transcription factors that regulate SSRP1 target genes. As potential biomarkers of drug synergy, we identified genes that were more strongly suppressed by the combination than by either single treatment, and whose increased expression predicted poorer survival in lung adenocarcinoma patients. Combination of quinacrine and erlotinib is synergistic in NSCLC through suppression of FACT, resulting in inhibition of cell cycle progression. RNA was isolated from cells treated with 1 M-NM-

ORGANISM(S): Homo sapiens

SUBMITTER: George Stark

PROVIDER: E-GEOD-57422 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Introduction: The clinical benefit of EGFR tyrosine kinase inhibitor (TKI) treatment in non-small cell lung cancer (NSCLC) patients with activating EGFR mutations is temporary, as virtually all patients develop acquired EGFR TKI resistance that occurs via diverse mechanisms. Here, we identified increased FGFR1 expression as such a resistance mechanism and using pathways analysis and drug combination testing we identified a novel combination treatment to control growth of these resistant tumors. Methods: Novel erlotinib-resistant NSCLC cell lines were generated and analyzed by mass spectrometry-based proteomics to identify altered pathways associated with erlotinib resistance. The altered pathways were further analyzed in gefitinib and osibenib resistant cell lines. Small molecule inhibitor combinations were used to block the altered pathways and investigate growth reduction in vitro and in two xenograft mouse models. FGFR1 mRNA levels were examined in pre- and (post?)- EGFR TKI treatment clinical tumor samples. Results: Proteomic analysis revealed increased expression of FGFR1 and AXL as well as increased Akt and ERK1/2 activation in a panel of novel erlotinib-resistant HCC827 cell lines. Combined treatment with erlotinib or osimertinib and a panel of small molecule inhibitors targeting AXL/MET, FGFRs, Akt, PI3K/mTOR, MEK or ERK1/2 showed that the most prominent re-sensitization to EGFR TKI occurred with the pan-FGFR inhibitor, PD173074. Interestingly, simultaneous blockade of components of the Akt pathway using specific Akt or dual PI3K-mTOR inhibitors combined with inhibitors targeting the FGFR family exhibited the most efficient growth inhibition of FGFR1 overexpressing EGFR TKI-resistant cell lines. Phosphorylation of proteins downstream of Akt, including PRAS40, FOXO and S6 ribosomal protein, were completely abrogated by PD173074 combined with the Akt inhibitor GSK2141795 . Combination treatment with PD173074 and an Akt inhibitor exhibited synergistic growth inhibition in vivo in two FGFR1 overexpressing NSCLC EGFR TKI-resistant animal models. Conclusion: The significant growth inhibition in vitro and in vivo observed with PD173074 combined with Akt compared to either drug alone imply that inhibition of several key targets may be beneficial in controlling erlotinib-resistant NSCLC. The complete abrogation of PRAS40, FOXO and S6 phosphorylations by PD173074 combined with an Akt inhibitor indicates that the Akt pathway is no longer active.

Project description:Mutations in the epidermal growth factor receptor (EGFR) kinase domain occur in 10-30% of lung adenocarcinoma. Leucine to arginine substitution at amino acid position 858 (L858R) accounts for around 50% of EGFR-tyrosine kinase inhibitor (TKI) sensitizing mutations. A second site mutation in the gatekeeper residue (T790M) accounts for around 60% of acquired resistance to EGFR-TKIs. We sought to identify the immediate direct and indirect targets of these mutant EGFRs in lung adenocarcinoma and their modulation by erlotinib, the first generation, and most widely used EGFR-directed TKI. We undertook stable isotope labeling of amino acids in cell culture (SILAC), phosphopeptide enrichment, and quantitative mass spectrometry to identify dynamic changes of phosphorylation downstream of mutant EGFRs in lung adenocarcinoma cells harboring L858R or L858R/T790M mutations and their modulation by erlotinib inhibition. Phosphorylation at the majority of phosphosites identified exhibited no change upon either EGF stimulation or erlotinib inhibition. Only around 7% of phosphosites identified and quantified showed increased phosphorylation upon EGF stimulation in either cell line. However, while phosphorylation at 61% of these phosphosites decreased upon erlotinib inhibition in the TKI sensitive H3255 cells, only 24% of such sites exhibited decreased phosphorylation upon erlotinib inhibition in the TKI resistant H1975 cells. Top canonical pathways that were inhibited upon erlotinib treatment in sensitive cells, but not the resistant cells include EGFR, Insulin receptor, HGF, MAPK, mTOR, p70S6K and JAK/STAT signaling. We identified phosphosites in proteins of the autophagy network, such as ULK1 (S623) that is constitutive phosphorylated in these lung adenocarcinoma cells, but phosphorylation is inhibited upon erlotinib treatment in sensitive cells, but not resistant cells. Finally, kinase-substrate prediction analysis from our data indicated that substrates of basophilic kinase families, AGC, CAMK and STE were significantly enriched and those of proline directed kinase families, CMGC and CK were significantly depleted among substrates that exhibit increased phosphorylation upon EGF stimulation and reduced phosphorylation upon TKI inhibition. This is the first study to date to examine global phosphorylation changes upon erlotinib treatment of lung adenocarcinoma cells and results from this study provide new insights into signaling downstream of mutant EGFRs in lung adenocarcinoma.

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Quinacrine Overcomes Resistance to Erlotinib by Inhibiting FACT, Nuclear Factor-kappa B and Cell Cycle Progression in Non-Small Cell Lung Cancer

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