Project description:Metabolic reprogramming is widely known as a hallmark of cancer cells to allow adaptation of cells to sustain survival signals. In the past decade, altered lipid metabolism has been recognized to be a property of malignant cells. In this report, we describe a novel oncogenic signaling pathway exclusively in tyrosine kinase inhibitor (TKI)-resistant epidermal growth factor receptor (EGFR) mutant non-small cell lung cancer (NSCLC). EGFR mediates TKI-resistance through regulation of the fatty acid synthase (FASN), and inhibition of this pathway using the FASN inhibitor Orlistat, triggers cell death and reduces tumor sizes both in culture systems and in vivo. Together, data shown here provide compelling evidence that the fatty acid metabolism pathway is a candidate target for TKI-resistant NSCLC treatment.
Project description:Aberrant overexpression or activation of EGFR drives the development of non-small cell lung cancer (NSCLC) and acquired resistance to EGFR tyrosine kinase inhibitors (TKIs) by secondary EGFR mutations or c-MET amplification/activation remains as a major hurdle for NSCLC treatment. We previously identified WDR4 as a substrate adaptor of Cullin 4 ubiquitin ligase and an association of WDR4 high expression with poor prognosis of lung cancer. Here, using an unbiased ubiquitylome analysis, we uncover PTPN23, a component of the ESCRT complex, as a substrate of WDR4- based ubiquitin ligase. WDR4-mediated PTPN23 ubiquitination leads to its proteasomal degradation, thereby suppressing lysosome trafficking and degradation of wild type EGFR, EGFR mutant, and c-MET. Through this mechanism, WDR4 sustains EGFR and c-MET signaling to promote NSCLC proliferation, migration, invasion, stemness, and metastasis. Clinically, PTPN23 is downregulated in lung cancer and its low expression correlates with WDR4 high expression and poor prognosis. Targeting WDR4-mediated PTPN23 ubiquitination by a peptide that competes with PTPN23 for binding WDR4 promotes EGFR and c-MET degradation to block the growth and progression of EGFR TKI-resistant NSCLC. These findings identify a central role of WDR4/PTPN23 axis in EGFR and c-MET trafficking and a potential therapeutic target for treating EGFR TKI-resistant NSCLC.
Project description:Epidermal growth factor receptor (EGFR) harboring active mutations, Del19 and L858R, are most common oncogenic mutations in in non-small cell lung cancer (NSCLC) patients. The preferred treatment at first line is tyrosine kinase inhibitor (TKI) administration while the TKI-resistance usually develops because of acquiring the secondary EGFR T790M mutant. Protein-protein interactions (PPIs) constitute the signaling scaffold and thus aberrant PPIs ascribed to mutations often results in dysregulations of downstream signaling cascades. Affinity purification coupled mass spectrometry (AP-MS) was utilized to characterize the EGFR PPIs in four NSCLC cells which carry different EGFR subtypes representing as TKI-sensitive and -resistant models in this study. The EGFR interactomes of TKI-resistant NSCLC cells presented higher diversity of subcellular distribution as well as the hyperactive EGFR trafficking. Furthermore, gefitinib perturbation activated autophagy-mediated EGFR degradation in TKI-resistant NSCLC models and inhibiting autophagy process indeed reduced the TKI-resistance against gefitinib as cytotoxicity was significantly improved. Alternatively, gefitinib induced EGFR translocation toward cell periphery through Rab7 ubiquitination in TKI-sensitive models which may confer TKIs more chance to suppress EGFR activity. In brief, acquired T790M EGFR mutation rewired the EGFR inherent interactomes and thus guided EGFR moving toward distinct trafficking routes, EGFR recycling or autophagy-mediated degradation, in response to TKI insult in TKI-sensitive and -resistant NSCLC cells. These finding suggest that manipulation or combined autophagy inhibition may provide us a novel therapeutic strategy to manage TKI-resistance and tumor relapse in NSCLC.
Project description:CEACAM family proteins have been extensively studied as cell adhesion molecules, yet the biological and clinical significance of CEACAM6 remains relatively unexplored. Our research identifies a significant increase in CEACAM6 expression in lung adenocarcinoma, particularly correlating with EGFR mutation status. In EGFR-mutated lung cancer cells, CEACAM6 knockdown induced apoptosis and reduced p-ERK1/2 signaling downstream of EGFR. Treatment with EGFR-tyrosine kinase inhibitors (TKIs) decreased CEACAM6 levels, leading to TKI-resistant lung cancer cells that exhibited reduced p-ERK1/2 and increased epithelial-mesenchymal transition (EMT) characteristics. Co-immunoprecipitation assays revealed an interaction between CEACAM6 and EGFR. Although CEACAM6 expression was lost in EGFR-TKI resistant cells, its re-expression stabilized EGFR and increased sensitivity to EGFR-TKIs. TGF-? treatment, which induced EMT, also decreased CEACAM6 expression and improved EGFR-TKI resistance. Further analysis showed that EGFR-TKI resistant lung cancer cells had lower H3K27ac epigenetic modification levels at the CEACAM6 locus than EGFR-TKI sensitive cells. Treatment with HDAC1/2 inhibitors in EGFR-TKI sensitive cells reduced CEACAM6 expression, induced EMT and TGF-?-ligand/receptor gene expression, and enhanced EGFR-TKI resistance. These data highlight the crucial role of CEACAM6 in maintaining oncogenic EGFR signaling and its regulation by cytokine stimulation and epigenetic modification, influencing EGFR-TKI sensitivity. Our findings underscore CEACAM6's potential as a valuable biomarker in EGFR-driven lung adenocarcinoma and its intricate involvement in EGFR-related pathways.
Project description:Osimertinib, a third-generation EGFR-TKI, has applied to non-small cell lung cancer harboring activated EGFR mutation with or without T790M. However, the appearance of tumors resistant to osimertinib has been reported. We established and characterized osimertinib-resistant cells derived from NCI-H1975 cells harboring activating EGFR and T790M mutation.
Project description:Intrinsic and acquired resistance represent major obstacles to optimize outcomes in epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) targeted therapy in lung adenocarcinoma (LUAD). Hence, a deeper understanding of EGFR-TKI resistance mechanisms in LUAD will potentially assist in formulating strategies to delay or overcome such resistance. Herein, it was observed that trefoil factor 3 (TFF3) is a crucial mediator of the LUAD EGFR-TKI response. TFF3 conferred intrinsic resistance to EGFR inhibition in LUAD by promotion of EGFR activation. TFF3 expression was also increased in acquired EGFR-TKI resistant LUAD, accompanied by reduced EGFR activation. YAP, a key mediator of the Hippo signaling, was positively regulated by TFF3 by post-transcriptional mechanisms and was responsible for acquired EGFR-TKI resistance mediated by TFF3. Inhibition of TFF3 by a small molecule inhibitor not only enhanced EGFR-TKI sensitivity in LUAD cells but also restored the sensitivity of acquired EGFR-TKI resistant LUAD cells to EGFR-TKIs in vitro and in vivo. These findings demonstrate a pivotal function of TFF3 in mediating EGFR-TKI resistance in LUAD and may offer a potential therapeutic mechanism for delaying or overcoming resistance to EGFR-TKIs.
Project description:Acquired resistance represents a bottleneck for effective molecular targeted therapy in lung cancer. Metabolic adaptation is a distinct hallmark of human lung cancer that might contribute to acquired resistance. In this study, we discovered a novel mechanism of acquired resistance to EGFR tyrosine kinase inhibitors (TKI) mediated by IGF2BP3-dependent cross-talk between epigenetic modifications and metabolic reprogramming through the IGF2BP3–COX6B2 axis. IGF2BP3 was upregulated in patients with TKI-resistant non–small cell lung cancer, and high IGF2BP3 expression correlated with reduced overall survival. Upregulated expression of the RNA binding protein IGF2BP3 in lung cancer cells reduced sensitivity to TKI treatment and exacerbated the development of drug resistance via promoting oxidative phosphorylation (OXPHOS). COX6B2 mRNA bound IGF2BP3, and COX6B2 was required for increased OXPHOS and acquired EGFR-TKI resistance mediated by IGF2BP3. Mechanistically, IGF2BP3 bound to the untranslated region of COX6B2 in an m6A-dependent manner to increase COX6B2 mRNA stability. Moreover, the IGF2BP3–COX6B2 axis regulated nicotinamide metabolism, which can alter OXPHOS and promote EGFR-TKI acquired resistance. Inhibition of OXPHOS with IACS-010759, a small-molecule inhibitor, resulted in strong growth suppression in vitro and in vivo in a gefitinib-resistant patient-derived xenograft model. Collectively, these findings suggest that metabolic reprogramming by the IGF2BP3–COX6B2 axis plays a critical role in TKI resistance and confers a targetable metabolic vulnerability to overcome acquired resistance to EGFR-TKIs in lung cancer.
Project description:The study was designed to identify the molecular changes that occur in EGFR mutant NSCLCs that become resistant to TKI by transforming to SCLC. Tyrosine kinase inhibitors (TKIs) are effective treatments for non-small cell lung cancers (NSCLCs) with epidermal growth factor receptor (EGFR) mutations. However, they do not lead to cures, and, on average, relapse occurs after one year of continuous treatment. In a subset of patients, a fundamental histological transformation from NSCLC to small cell lung cancer (SCLC) is observed in the resistant cancers, but the molecular changes associated with this transformation remain unknown. Analysis of a cohort of tumor samples and cell lines derived from resistant EGFR mutant patients with SCLC transformation revealed that RB is lost in 100% of these cases, but rarely in those that remain NSCLC. Global changes in gene expression, including increased neuroendocrine marker expression and absence of EGFR expression, are observed in cancers that transformed to SCLC. Consistent with their genetic and epigenetic similarities to classical SCLC, cell lines derived from resistant EGFR mutant SCLC biopsies are substantially more sensitive to ABT-263 treatment compared to those derived from resistant EGFR mutant NSCLCs. Together, these findings suggest that despite developing initially as EGFR mutant adenocarcinomas, this subset of resistant cancers ultimately take on many of the molecular and phenotypic characteristics of classical SCLC. Overall, we completed array CGH analysis on 4 tumor specimens from EGFR mutant, TKI-resistant patients. Three of these samples had transformed to SCLC and one remained NSCLC.
Project description:In this study, we explored the mechanisms of hypoxia-induced EGFR TKI resistance in non-small cell lung cancer (NSCLC) harbored activating EGFR mutation. The NSCLC cell lines were exposed to normorxia or 1% oxygen for 4 weeks, and then we tested EGFR TKI sensitivity in normoxic and hypoxic NSCLC cell lines. In this microarray experiment, we used normoxic HCC827 and hypoxia-induced gefitinib resistant clones, C2-3 and C2-10. Those clones were selected with gefitinib treatment after the HCC827 were exposed to 1% oxygen for 4 weeks, and the HCC827 C2-3 and C2-10 clones were selected at random for this study.
Project description:EGFR tyrosine kinase inhibitors cause dramatic responses in EGFR-mutant lung cancer, but resistance universally develops. The involvement of β-catenin in EGFR TKI resistance has been previously reported however the precise mechanism by which β-catenin activation contributes to EGFR TKI resistance is not clear. Here, we show that EGFR inhibition results in the activation of β-catenin signaling in a Notch3-dependent manner, which facilitates the survival of a subset of cells that we call “adaptive persisters”. We previously reported that EGFR-TKI treatment rapidly activates Notch3, and here describe the physical association of Notch3 with β-catenin, leading to increased stability and activation of β-catenin. We demonstrate that the combination of EGFR-TKI and a β-catenin inhibitor inhibits the development of these adaptive persisters, decreases tumor burden, improves recurrence free survival, and overall survival in xenograft models. These results supports combined EGFR-TKI and β-catenin inhibition in patients with EGFR mutant lung cancer.