MYC expression and fatty acid oxidation in EGFR-TKI acquired resistance.

This report expands on our previous research, highlighting a unique inverse correlation between MYC expression in tumor cells and immune cells during the development of EGFR-TKI resistance. It is observed that MYC expression and fatty acid oxidation (FAO) metabolism in tissue-resident memory (TRM) CD8 + T cells are significantly impaired. These findings offer new insights into the mechanisms of TKI resistance. Although the study is preliminary, it suggests caution when interpreting the effectiveness of MYC inhibitors in reversing TKI resistance, especially when immune factors are not considered.

The later-line efficacy and safety of immune checkpoint inhibitors plus anlotinib in EGFR-mutant patients with EGFR-TKI-resistant NSCLC: a single-center retrospective study.

BACKGROUND: Effective treatment after EGFR-TKI resistance is of great clinical concern. We aimed to investigate the efficacy and safety of anlotinib in combination with an anti-PD-1/PD-L1 antibody in later-line therapy for EGFR-mutant NSCLC patients after TKI treatment failure and to explore the independent predictive factors of therapeutic efficacy. METHODS: A total of 71 patients with confirmed advanced EGFR-mutated NSCLC who progressed after previous standard EGFR-TKI therapy but still failed after multiline treatments were included retrospectively in this study. Most of the patients had previously received at least three lines of treatment. All were treated with anlotinib combined with anti-PD-1 or anti-PD-L1 therapy. The safety of this combined treatment was assessed by the incidence of adverse events. The efficacy of the regimens was evaluated by survival analysis (OS, PFS, ORR, DCR). RESULTS: The median follow-up period was 28.6 months (range: 2.3-54.0 months), and the median number of treatment lines was 4. The overall response rate (ORR) and disease control rate (DCR) were 19.7% and 77.5%, respectively. The median PFS was 5.8 months (95% CI 4.2-7.4 months), and the median OS was 17.1 months (95% CI 12.0-22.3 months). Patients who received immune checkpoint inhibitors plus anlotinib had an encouraging intracranial ORR of 38.5% and a DCR of 80.8%. ECOG performance status < 2 at baseline was independent protective factors of PFS. Metastatic organs and ECOG performance status were independent parameters in predicting OS. Treatment-related adverse events occurred in 66 (93.0%) patients; most of the adverse events were Grade 1-2, and no increase in adverse events was observed compared to monotherapy. CONCLUSION: Anlotinib combined with an anti-PD-1/PD-L1-based regimen exhibited promising efficacy and tolerance in NSCLC patients with EGFR mutations after previous TKI failure. The efficacy of this combined regimen in patients with EGFR mutations should be further evaluated.

DUSP5 regulated by YTHDF1-mediated m6A modification promotes epithelial-mesenchymal transition and EGFR-TKI resistance via the TGF-ß/Smad signaling pathway in lung adenocarcinoma.

BACKGROUND: Lung adenocarcinoma (LUAD) patients have a dismal survival rate because of cancer metastasis and drug resistance. The study aims to identify the genes that concurrently modulate EMT, metastasis and EGFR-TKI resistance, and to investigate the underlying regulatory mechanisms. METHODS: Cox regression and Kaplan-Meier analyses were applied to identify prognostic oncogenes in LUAD. Gene set enrichment analysis (GSEA) was used to indicate the biological functions of the gene. Wound-healing and Transwell assays were used to detect migratory and invasive ability. EGFR-TKI sensitivity was evaluated by assessing the proliferation, clonogenic survival and metastatic capability of cancer cells with treatment with gefitinib. Methylated RNA immunoprecipitation (MeRIP) and RNA immunoprecipitation (RIP) analyses established the level of m6A modification present on the target gene and the protein's capability to interact with RNA, respectively. Single-sample gene set enrichment (ssGSEA) algorithm used to investigate levels of immune cell infiltration. RESULTS: Our study identified dual-specificity phosphatase 5 (DUSP5) as a novel and powerful predictor of adverse outcomes for LUAD by using public datasets. Functional enrichment analysis found that DUSP5 was positively enriched in EMT and transforming growth factor-beta (TGF-ß) signaling pathway, a prevailing pathway involved in the induction of EMT. As expected, DUSP5 knockdown suppressed EMT via inhibiting the canonical TGF-ß/Smad signaling pathway in in vitro experiments. Consistently, knockdown of DUSP5 was first found to inhibit migratory ability and invasiveness of LUAD cells in in vitro and prevent lung metastasis in in vivo. DUSP5 knockdown re-sensitized gefitinib-resistant LUAD cells to gefitinib, accompanying reversion of EMT progress. In LUAD tissue samples, we found 14 cytosine-phosphate-guanine (CpG) sites of DUSP5 that were negatively associated with DUSP5 gene expression. Importantly, 5'Azacytidine (AZA), an FDA-approved DNA methyltransferase inhibitor, restored DUSP5 expression. Moreover, RIP experiments confirmed that YTH N6-methyladenosine RNA binding protein 1 (YTHDF1), a m6A reader protein, could bind DUSP5 mRNA. YTHDF1 promoted DUSP5 expression and the malignant phenotype of LUAD cells. In addition, the DUSP5-derived genomic model revealed the two clusters with distinguishable immune features and tumor mutational burden (TMB). CONCLUSIONS: Briefly, our study discovered DUSP5 which was regulated by epigenetic modification, might be a potential therapeutic target, especially in LUAD patients with acquired EGFR-TKI resistance.

Overall signature of acquired KRAS gene changes in advanced non-small cell lung cancer patient with EGFR-TKI resistance.

OBJECTIVE: Numerous scattered case studies continue to demonstrate a strong correlation between acquired KRAS mutations and epidermal growth factor receptor-tyrosine kinase inhibitor resistance in non-small cell lung cancer. However, the comprehensive understanding of the KRAS pathway following the failure of epidermal growth factor receptor-tyrosine kinase inhibitor therapy remains limited. METHODS: We conducted a retrospective evaluation of the next generation sequencing data from 323 patients with advanced non-small cell lung cancer and EGFR-activating mutations after experiencing progression with epidermal growth factor receptor-tyrosine kinase inhibitor therapy. Our analysis specifically focused on the acquired changes to the KRAS gene. RESULTS: Among the 323 patients with advanced non-small cell lung cancer and EGFR-activating mutations who experienced resistance to epidermal growth factor receptor-tyrosine kinase inhibitor therapy, 14 individuals (4.3%) developed resistance due to acquired KRAS alterations. Of these 14 patients, 10 cases (71.4%) were due to KRAS missense mutations, 1 case (7.2%) was due to KRAS gene fusion and 3 cases (21.4%) were due to KRAS amplification. Notably, we identified one newly demonstrated KRAS gene fusion (KRAS and LMNTD1), one KRAS G13D and one KRAS K117N. The emergence of acquired KRAS alterations was often accompanied by novel mutations and high tumor mutation burden, with TP53, CNKN2A, PIK3CA, MYC, STK11, CDK4, BRCA2 and ERBB2 being the most frequently observed concurrent mutations. The median progression-free survival and overall survival for the 14 patients were 5.2 and 7.3 months, respectively. Acquired KRAS missense variants were associated with significantly worse progression-free survival compared with other KRAS variant subtypes (P < 0.028). CONCLUSIONS: This study provides significant evidence of the role of acquired KRAS variants in the development of resistance to epidermal growth factor receptor-tyrosine kinase inhibitor therapy. Our results contribute to the growing body of knowledge on the mutational profiles associated with resistance to epidermal growth factor receptor-tyrosine kinase inhibitor treatment. Furthermore, our study highlights the KRAS gene change as a significant mechanism of resistance to epidermal growth factor receptor-tyrosine kinase inhibitor therapy.

Chemotherapy versus personalized therapy for EGFR mutant lung adenocarcinoma resistance to EGFR-tyrosine kinase inhibitors: a retrospective dual-center study.

BACKGROUND: Advanced lung adenocarcinoma patients often develop resistance to EGFR tyrosine kinase inhibitors (EGFR-TKIs), leaving uncertainties regarding subsequent treatment strategies. Although personalized therapy targeting individual acquired resistances (ARs) shows promise, its efficacy has not been systematically compared with platinum-containing doublet chemotherapy, a widely accepted treatment after EGFR-TKIs failure. METHODS: A retrospective dual-center study was conducted involving patients with advanced lung adenocarcinoma and EGFR mutations who developed resistance to EGFR-TKIs between January 2017 and December 2022. Eligible patients were adults aged 18 years or older with an Eastern Cooperative Oncology Group score of 0-1, normal organ function, and no prior chemotherapy. Patients were divided into the chemotherapy group (CG) or personalized therapy group (PG) based on the treatment received after disease progression. The primary endpoints were progression-free survival (PFS) and objective response rate (ORR). RESULTS: Of the 144 patients enrolled, there were 53 patients in the PG and 91 patients in the CG. The PG acquired resistance to EGFR-TKIs through the MET amplification (27, 50%) and small cell lung cancer transformation (16, 30%) and 18% of them reported multiple resistance mechanisms. The ORR of the PG was similar to that of the CG (34% vs. 33%, P = 1.0) and the PFS of the PG patients was not statistically different from that of their CG counterparts [4.2 months (95% CI: 3.6-4.8 months) vs. 5.3 months (95% CI: 4.6-6.0 months), P = 0.77]. CONCLUSIONS: These findings suggest that the therapeutic efficacy of chemotherapy approximates to that of personalized therapy, which signifies that chemotherapy is still a reliable choice for patients who develop resistance to EGFR-TKIs and that further research is awaited to explore the benefit of personalized treatment.

Single-cell transcriptional profiling uncovers the association between EOMES+CD8+ T cells and acquired EGFR-TKI resistance.

Acquired resistance to tyrosine kinase inhibitors (TKIs) is reportedly inevitable in lung cancers harboring epidermal growth factor receptor (EGFR) mutations, emphasizing the need for novel approaches to predict EGFR-TKI resistance for clinical monitoring and patient management. This study identified a significant increase in eomesodermin (EOMES)+CD8+ T cells in the TKI-resistant patients, which was correlated with poor survival. The increase in EOMES+CD8+ T cells was further confirmed in both tissue samples and peripheral blood of patients with TKIs resistance. The integrated analysis of pseudotime and Gene set variation showed that the increase in EOMES+CD8+ T cells may be attributed to TRM T cell conversion and metabolic reprogramming. Overall, this work suggested an association between the increased number of EOMES+CD8+ T cells and acquired TKI drug resistance, supporting the utility of EOMES+CD8+ T cells as a biomarker for TKI treatment response.

Co-Expression Network Analysis Unveiled lncRNA-mRNA Links Correlated to Epidermal Growth Factor Receptor-Tyrosine Kinase Inhibitor Resistance and/or Intermediate Epithelial-to-Mesenchymal Transition Phenotypes in a Human Non-Small Cell Lung Cancer Cellular Model System.

We investigated mRNA-lncRNA co-expression patterns in a cellular model system of non-small cell lung cancer (NSCLC) sensitive and resistant to the epithelial growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) erlotinib/gefitinib. The aim of this study was to unveil insights into the complex mechanisms of NSCLC targeted therapy resistance and epithelial-to-mesenchymal transition (EMT). Genome-wide RNA expression was quantified for weighted gene co-expression network analysis (WGCNA) to correlate the expression levels of mRNAs and lncRNAs. Functional enrichment analysis and identification of lncRNAs were conducted on modules associated with the EGFR-TKI response and/or intermediate EMT phenotypes. We constructed lncRNA-mRNA co-expression networks and identified key modules and their enriched biological functions. Processes enriched in the selected modules included RHO (A, B, C) GTPase and regulatory signaling pathways, apoptosis, inflammatory and interleukin signaling pathways, cell adhesion, cell migration, cell and extracellular matrix organization, metabolism, and lipid metabolism. Interestingly, several lncRNAs, already shown to be dysregulated in cancer, are connected to a small number of mRNAs, and several lncRNAs are interlinked with each other in the co-expression network.

Full spectrum flow cytometry-powered comprehensive analysis of PBMC as biomarkers for immunotherapy in NSCLC with EGFR-TKI resistance.

BACKGROUND: Clinical studies suggest that immune checkpoint inhibitor (ICI) monotherapy has limited benefits in non-small cell lung cancer (NSCLC) patients after epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) failure. However, data about efficacy of ICI plus chemotherapy remain controversial, probably attributed to the heterogeneity among such population, and robust efficacy biomarkers are urgent to explore. METHODS: A total of 60 eligible patients who received ICI plus chemotherapy after EGFR-TKI treatment failure were enrolled, 24 of whom peripheral blood mononuclear cell (PBMC) samples were collected at baseline and after 2 cycles of treatment. We have designed a 23-color-antibody panel to detect PBMC by full spectrum flow cytometry. RESULTS: For EGFR-TKI resistant NSCLC patients: 1) ICI plus chemotherapy achieved an objective response rate (ORR) of 21.7% and a median progression-free survival (PFS) of 6.4 months. 2) clinical characteristics associated with worse efficacy included liver metastasis and platelet-to-lymphocyte ratio (PLR) > 200. 3) the proportion of immune cell subset associated with better efficacy was higher baseline effective CD4+T cells (E4). 4) the baseline expression of immune checkpoint proteins (ICPs) on cell subsets associated with better efficacy included: higher expression of CD25 on dendritic cells (DC) and central memory CD8+T cells (CM8), and higher expression of Lymphocyte activation gene 3 (LAG-3) on effective memory CD8+T cells (EM8). 5) the expression of ICPs after 2 cycles of treatment associated with better efficacy included: higher expression of CD25 on CD8+T/EM8 /natural killer (NK) cells. 6) the dynamic changes of ICPs expression associated with worse efficacy included: significantly decrease of T cell immunoglobulin and ITIM domain (TIGIT) expression on regular T cells (Tregs) and decrease of V-domain immunoglobulin suppressor of T cell activation (VISTA) expression on Th1. 7) a prediction model for the efficacy of ICI plus chemotherapy was successfully constructed with a sensitivity of 62.5%, specificity of 100%, and area under curve (AUC) = 0.817. CONCLUSIONS: Some EGFR-TKI-resistant NSCLC patients could indeed benefit from ICI plus chemotherapy, but most patients are primary resistant to immunotherapy. Comprehensive analysis of peripheral immune cells using full spectrum flow cytometry showed that compared to the proportion of cell subsets, the expression type and level of ICPs on immune cells, especially CD25, were significantly correlated with the efficacy of immunotherapy.

Multiomics analysis revealed the mechanisms related to the enhancement of proliferation, metastasis and EGFR-TKI resistance in EGFR-mutant LUAD with ARID1A deficiency.

INTRODUCTION: Dysregulated ARID1A expression is frequently detected in lung adenocarcinoma (LUAD) and mediates significant changes in cancer behaviors and a poor prognosis. ARID1A deficiency in LUAD enhances proliferation and metastasis, which could be induced by activation of the Akt signaling pathway. However, no further exploration of the mechanisms has been performed. METHODS: Lentivirus was used for the establishment of the ARID1A knockdown (ARID1A-KD) cell line. MTS and migration/invasion assays were used to examine changes in cell behaviors. RNA-seq and proteomics methods were applied. ARID1A expression in tissue samples was determined by IHC. R software was used to construct a nomogram. RESULTS: ARID1A KD significantly promoted the cell cycle and accelerated cell division. In addition, ARID1A KD increased the phosphorylation level of a series of oncogenic proteins, such as EGFR, ErbB2 and RAF1, activated the corresponding pathways and resulted in disease progression. In addition, the bypass activation of the ErbB pathway, the activation of the VEGF pathway and the expression level changes in epithelial-mesenchymal transformation biomarkers induced by ARID1A KD contributed to the insensitivity to EGFR-TKIs. The relationship between ARID1A and the sensitivity to EGFR-TKIs was also determined using tissue samples from LUAD patients. CONCLUSION: Loss of ARID1A expression influences the cell cycle, accelerates cell division, and promotes metastasis. EGFR-mutant LUAD patients with low ARID1A expression had poor overall survival. In addition, low ARID1A expression was associated with a poor prognosis in EGFR-mutant LUAD patients who received first-generation EGFR-TKI treatment. Video abstract.

The Role of Proteomics and Phosphoproteomics in the Discovery of Therapeutic Targets and Biomarkers in Acquired EGFR-TKI-Resistant Non-Small Cell Lung Cancer.

The discovery of potent EGFR-tyrosine kinase inhibitors (EGFR-TKIs) has revolutionized the treatment of EGFR-mutated lung cancer. Despite the fact that EGFR-TKIs have yielded several significant benefits for lung cancer patients, the emergence of resistance to EGFR-TKIs has been a substantial impediment to improving treatment outcomes. Understanding the molecular mechanisms underlying resistance is crucial for the development of new treatments and biomarkers for disease progression. Together with the advancement in proteome and phosphoproteome analysis, a diverse set of key signaling pathways have been successfully identified that provide insight for the discovery of possible therapeutically targeted proteins. In this review, we highlight the proteome and phosphoproteomic analyses of non-small cell lung cancer (NSCLC) as well as the proteome analysis of biofluid specimens that associate with acquired resistance in response to different generations of EGFR-TKI. Furthermore, we present an overview of the targeted proteins and potential drugs that have been tested in clinical studies and discuss the challenges of implementing this discovery in future NSCLC treatment.

Identification of RET fusions in a Chinese multicancer retrospective analysis by next-generation sequencing.

Fusion of RET with different partner genes has been detected in papillary thyroid, lung, colorectal, pancreatic, and breast cancer. Approval of selpercatinib for treatment of lung and thyroid cancer with RET gene mutations or fusions calls for studies to explore RET fusion partners and their eligibility for RET-based targeted therapy. In this study, RET fusion patterns in a large group of Chinese cancer patients covering several cancer types were identified using next-generation sequencing. A total of 44 fusion patterns were identified in the study cohort with KIF5B, CCDC6, and ERC1 being the most common RET fusion partners. Notably, 17 novel fusions were first reported in this study. Prevalence of functional RET fusions was 1.05% in lung cancer, 6.03% in thyroid cancer, 0.39% in colorectal cancer, and less than 0.1% in gastric cancer and hepatocellular carcinoma. Analysis showed a preference for fusion partners in different tumor types, with KIF5B being the common type in lung cancer, CCDC6 in thyroid cancer, and NCOA4 in colorectal cancer. Co-occurrence of EGFR mutations and RET fusions with rare partner genes (rather than KIF5B) in lung cancer patients was correlated with epidermal growth factor receptor-tyrosine kinase inhibitor resistance and could predict response to targeted therapies. Findings from this study provide a guide to clinicians in determining tumors with specific fusion patterns as candidates for RET targeted therapies.

IRS4 promotes the progression of non-small cell lung cancer and confers resistance to EGFR-TKI through the activation of PI3K/Akt and Ras-MAPK pathways.

IRS4 is a member of the insulin receptor substrate (IRS) protein family. It acts as a cytoplasmic adaptor protein, integrating and transmitting signals from receptor protein tyrosine kinases to the intracellular environment. IRS4 can induce mammary tumorigenesis and is usually overexpressed in non-small cell lung cancer (NSCLC). However, little is known about the role of IRS4 in the development and progression of lung cancer. In this study, we show that IRS4 knockout suppresses the proliferation, colony formation, migration, and invasion of A549 lung cancer cells, as well as tumor growth in a nude mouse xenograft model. In contrast, stable expression of IRS4 showed the opposite effects. As expected, IRS4 was found to activate the PI3K/Akt and Ras-MAPK pathways, and we also showed that IRS4 depletion significantly enhanced the sensitivity of EGFR tyrosine kinase inhibitor (EGFR-TKI)-resistant cells to gefitinib. Taken together, these results show that IRS4 promotes NSCLC progression and may represent a potential therapeutic target for EGFR-TKI-resistant NSCLC.

LMNA Reduced Acquired Resistance to Erlotinib in NSCLC by Reversing the Epithelial-Mesenchymal Transition via the FGFR/MAPK/c-fos Signaling Pathway.

For patients exhibiting non-small-cell lung cancer (NSCLC) with activating epidermal growth factor receptor (EGFR) mutations, epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) are a first-line treatment. However, most patients who initially responded to EGFR-TKIs eventually developed acquired resistance, limiting the effectiveness of therapy. It has long been known that epithelial-mesenchymal transition (EMT) leads to acquired resistance to EGFR-TKIs in NSCLC. However, the mechanisms underlying the resistance dependent on EMT are unknown. This research aimed to reveal the effects of LMNA in the regulation of acquired resistance to erlotinib by EMT in NSCLC. The acquired erlotinib-resistant cells (HCC827/ER) were induced by gradual increase of concentrations of erlotinib in erlotinib-sensitive HCC827 cells. RNA sequencing and bioinformatics analysis were performed to uncover the involvement of LMNA in the EMT process that induced acquired resistance to erlotinib. The effect of LMNA on cell proliferation and migration was measured by clone-formation, wound-healing, and transwell assays, respectively. The EMT-related protein, nuclear shape and volume, and cytoskeleton changes were examined by immunofluorescence. Western blot was used to identify the underlying molecular mechanism of LMNA regulation of EMT. HCC827/ER cells with acquired resistance to erlotinib underwent EMT and exhibited lower LMNA expression compared to parental sensitive cells. LMNA negatively regulated the expression of EMT markers; HCC827/ER cells showed a significant up-regulation of mesenchymal markers, such as CDH2, SNAI2, VIM, ZEB1, and TWIST1. The overexpression of LMNA in HCC827/ER cells significantly inhibited EMT and cell proliferation, and this inhibitory effect of LMNA was enhanced in the presence of 2.5 µM erlotinib. Furthermore, a decrease in LMNA expression resulted in a higher nuclear deformability and cytoskeletal changes. In HCC827/ER cells, AKT, FGFR, ERK1/2, and c-fos phosphorylation levels were higher than those in HCC827 cells; Furthermore, overexpression of LMNA in HCC827/ER cells reduced the phosphorylation of AKT, ERK1/2, c-fos, and FGFR. In conclusion, our findings first demonstrated that downregulation of LMNA promotes acquired EGFR-TKI resistance in NSCLC with EGFR mutations by EMT. LMNA inhibits cell proliferation and migration of erlotinib-resistant cells via inhibition of the FGFR/MAPK/c-fos signaling pathway. These findings indicated LMNA as a driver of acquired resistance to erlotinib and provided important information about the development of resistance to erlotinib treatment in NSCLC patients with EGFR mutations.

The Root Extract of Peucedanum praeruptorum Dunn Exerts Anticancer Effects in Human Non-Small-Cell Lung Cancer Cells with Different EGFR Mutation Statuses by Suppressing MET Activity.

The aim of this study was to investigate the anticancer effects of the root extract of Peucedanum praeruptorum Dunn (EPP) in human non-small-cell lung cancer (NSCLC) cells and explore the mechanisms of action. We used four types of human lung cancer cell lines, including H1299 (epidermal growth factor receptor (EGFR) wild-type), PC9 (EGFR Glu746-Ala750 deletion mutation in exon 19; EGFR tyrosine kinase inhibitor (TKI)-sensitive), H1975 (EGFR L858R/T790M double-mutant; EGFR TKI-resistant), and PC9/ER (erlotinib-resistant) cells. EPP suppressed cell growth and the colony formation of NSCLC cells in a concentration-dependent manner. EPP stimulated chromatin condensation, increased the percentage of sub-G1 phase cells, and enhanced the proportion of annexin V-positive cells, demonstrating that EPP triggered apoptosis in NSCLC cells regardless of the EGFR mutation and EGFR TKI resistance status. The phosphorylation level of the signal transducer and activator of transcription 3 (STAT3) and AKT was decreased by EPP. The expression of STAT3 target genes was also downregulated by EPP. EPP reversed hepatocyte growth factor (HGF)-induced MET phosphorylation and gefitinib resistance. Taken together, our results demonstrate that EPP exerted anticancer effects not only in EGFR TKI-sensitive NSCLC cells, but also in EGFR TKI-resistant NSCLC cells, by suppressing MET activity.

EGFR mutation mediates resistance to EGFR tyrosine kinase inhibitors in NSCLC: From molecular mechanisms to clinical research.

With the development of precision medicine, molecular targeted therapy has been widely used in the field of cancer, especially in non-small-cell lung cancer (NSCLC). Epidermal growth factor receptor (EGFR) is a well-recognized and effective target for NSCLC therapies, targeted EGFR therapy with EGFR-tyrosine kinase inhibitors (EGFR-TKIs) has achieved ideal clinical efficacy in recent years. Unfortunately, resistance to EGFR-TKIs inevitably occurs due to various mechanisms after a period of therapy. EGFR mutations, such as T790M and C797S, are the most common mechanism of EGFR-TKI resistance. Here, we discuss the mechanisms of EGFR-TKIs resistance induced by secondary EGFR mutations, highlight the development of targeted drugs to overcome EGFR mutation-mediated resistance, and predict the promising directions for development of novel candidates.

Targeting DNA-PK overcomes acquired resistance to third-generation EGFR-TKI osimertinib in non-small-cell lung cancer.

The third-generation of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs), represented by osimertinib, has achieved remarkable clinical outcomes in the treatment of non-small-cell lung cancer (NSCLC) with EGFR mutation. However, resistance eventually emerges in most patients and the underlying molecular mechanisms remain to be fully understood. In this study, we generated an osimertinib-acquired resistant lung cancer model from a NSCLC cell line H1975 harboring EGFR L858R and T790M mutations. We found that the capacity of DNA damage repair was compromised in the osimertinib resistant cells, evidenced by increased levels of γH2AX and higher intensity of the comet tail after withdrawal from cisplatin. Pharmacological inhibiting the activity or genetic knockdown the expression of DNA-PK, a key kinase in DNA damage response (DDR), sensitized the resistant cells to osimertinib. Combination of osimertinib with the DNA-PK inhibitor, PI-103, or NU7441, synergistically suppressed the proliferation of the resistant cells. Mechanistically, we revealed that DNA-PK inhibitor in combination with osimertinib resulted in prolonged DNA damage and cell cycle arrest. These findings shed new light on the mechanisms of osimertinib resistance in the aspect of DNA repair, and provide a rationale for targeting DNA-PK as a therapeutic strategy to overcome osimertinib-acquired resistance in NSCLC.

ELF3 Is a Target That Promotes Therapeutic Efficiency in EGFR Tyrosine Kinase Inhibitor-Resistant Non-Small Cell Lung Cancer Cells via Inhibiting PKCί.

(1) Background: Mutations in epidermal growth factor receptor (EGFR) proteins account for many non-small cell lung cancers (NSCLCs), and EGFR tyrosine kinase inhibitors (TKIs) are being used as targeted therapeutics. However, resistance to TKIs continues to increase owing to additional mutations in more than half of the patients receiving EGFR TKI therapy. In addition to targeting new mutations with next-generation therapeutics, it is necessary to find an alternative target to overcome the challenges associated with resistance. (2) Methods: To identify potential alternative targets in patients with NSCLC undergoing targeted therapy, putative targets were identified by transcriptome profiling and validated for their biological and therapeutic effects in vitro and in vivo. (3) Results: ELF3 was found to be differentially expressed in NSCLC, and ELF3 knockdown significantly increased cell death in K-Ras mutant as well as in EGFR L858R/T790M mutation harboring lung cancer cells. We also found that auranofin, an inhibitor of protein kinase C iota (PKCί), a protein upstream of ELF3, effectively induced cell death. (4) Conclusions: Our study suggests that blocking ELF3 is an effective way to induce cell death in NSCLC with K-Ras and EGFR T790M/L858R mutations and thus advocates the use of auranofin as an effective alternative drug to overcome EGFR TKI resistance.

The Root Extract of Scutellaria baicalensis Induces Apoptosis in EGFR TKI-Resistant Human Lung Cancer Cells by Inactivation of STAT3.

Resistance to epidermal growth factor receptor tyrosine kinase inhibitors (EGFR TKIs) is a major obstacle in managing lung cancer. The root of Scutellaria baicalensis (SB) traditionally used for fever clearance and detoxification possesses various bioactivities including anticancer effects. The purpose of this study was to investigate whether SB exhibited anticancer activity in EGFR TKI-resistant lung cancer cells and to explore the underlying mechanism. We used four types of human lung cancer cell lines, including H1299 (EGFR wildtype; EGFR TKI-resistant), H1975 (acquired TKI-resistant), PC9/ER (acquired erlotinib-resistant), and PC9/GR (acquired gefitinib-resistant) cells. The ethanol extract of SB (ESB) decreased cell viability and suppressed colony formation in the four cell lines. ESB stimulated nuclear fragmentation and the cleavage of poly(ADP-ribose) polymerase (PARP) and caspase-3. Consistently, the proportion of sub-G1 phase cells and annexin V+ cells were significantly elevated by ESB, indicating that ESB induced apoptotic cell death in EGFR TKI-resistant cells. ESB dephosphorylated signal transducer and activator of transcription 3 (STAT3) and downregulated the target gene expression. The overexpression of constitutively active STAT3 reversed ESB-induced apoptosis, suggesting that ESB triggered apoptosis in EGFR TKI-resistant cells by inactivating STAT3. Taken together, we propose the potential use of SB as a novel therapeutic for lung cancer patients with EGFR TKI resistance.

Exosomes transmit T790M mutation-induced resistance in EGFR-mutant NSCLC by activating PI3K/AKT signalling pathway.

Emerging evidence has shown that exosomes derived from drug-resistant tumour cells are able to horizontally transmit drug-resistant phenotype to sensitive cells. However, whether exosomes shed by EGFR T790M-mutant-resistant NSCLC cells could transfer drug resistance to sensitive cells has not been investigated. We isolated exosomes from the conditioned medium (CM) of T790M-mutant NSCLC cell line H1975 and sensitive cell line PC9. The role and mechanism of exosomes in regulating gefitinib resistance was investigated both in vitro and in vivo. Exosome-derived miRNA expression profiles from PC9 and H1975 were analysed by small RNA sequencing and confirmed by qRT-PCR. We found that exosomes shed by H1975 could transfer gefitinib resistance to PC9 both in vitro and in vivo through activating PI3K/AKT signalling pathway. Small RNA sequencing and RT-PCR confirmed that miR-3648 and miR-522-3p were the two most differentially expressed miRNAs and functional study showed that up-regulation of miR-522-3p could induce gefitinib resistance in PC9 cell. The findings of our study reveal an important mechanism of acquired resistance to EGFR-TKIs in NSCLC.

Lymecycline reverses acquired EGFR-TKI resistance in non-small-cell lung cancer by targeting GRB2.

Epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) were first-line treatments for NSCLC patients with EGFR-mutations. However, about 30 % of responders relapsed within six months because of acquired resistance. In this study, we used Connectivity Map (CMap) to discover a drug capable of reversing acquired EGFR-TKIs resistance. To investigate Lymecycline's ability to reverse acquired EGFR-TKIs resistance, two Icotinib resistant cell lines were constructed. Lymecycline's ability to suppress the proliferation of Icotinib resistant cells in vitro and in vivo was then evaluated. Molecular targets were predicted using network pharmacology and used to identify the molecular mechanism. Growth factor receptor-bound protein 2 (GRB2) is an EGFR-binding adaptor protein essential for EGFR phosphorylation and regulation of AKT/ERK/STAT3 signaling pathways. Lymecycline targeted GRB2 and inhibited the resistance of the cell cycle to EGFR-TKI, arresting disease progression and inducing apoptosis in cancer cells. Combined Lymecycline and Icotinib treatment produced a synergistic effect and induced apoptosis in HCC827R5 and PC9R10 cells. Cell proliferation in resistant cancer cells was significantly inhibited by the combined Lymecycline and Icotinib treatment in mouse models. Lymecycline inhibited the resistance of the cell cycle to EGFR-TKI and induced apoptosis in NSCLC by inhibiting EGFR phosphorylation and GRB2-mediated AKT/ERK/STAT3 signaling pathways. This provided strong support that Lymecycline when combined with EGFR targeting drugs, enhanced the efficacy of treatments for drug-resistant NSCLC.