Tyrosine Kinase Inhibitors Resistance In Non-small Cell Lung Cancer Research Articles

Dual Roles of Lactate in EGFR-TKI-Resistant Lung Cancer by Targeting GPR81 and MCT1.

Lactate is critical in modeling tumor microenvironment causing chemotherapy resistance; however, the role of lactate in tyrosine kinase inhibitor (TKI) resistance has not been fully known. The aim of this study was to evaluate whether lactate could mediate TKI resistance through GPR81 and MCT1 in non-small-cell lung cancer (NSCLC). Here, we showed that lactate enhanced the cell viability and restrained erlotinib-induced apoptosis in PC9 and HCC827 cells. GPR81 and AKT expression were significantly increased with the addition of lactate, and siGPR81 reduced AKT expression resulting in a raised apoptosis rate with erlotinib treatment. Furthermore, we found that lactate also promoted MCT1 exposure, and inhibiting MCT1 with AZD3965 markedly impaired the glycolytic capacity. A significant increase of GPR81 and MCT1 expression was observed in insensitive tissues compared with sensitive ones by immunostaining in NSCLC patients. Our results indicate that lactate adopts dual strategies to promote TKI resistance in NSCLC, not only activating AKT signaling by GPR81, but also giving energy supply through MCT1-mediated input. Targeting GPR81 and MCT1 may provide new therapeutic modalities for TKI resistance in NSCLC.

Transformation of invasive lung adenocarcinoma with ALK rearrangement into pulmonary sarcomatoid carcinoma

Anaplastic lymphoma kinase (ALK) tyrosine kinase inhibitors (TKIs) improve outcomes for non-small-cell lung cancer (NSCLC) patients with ALK fusions. Nevertheless, ALK TKI resistance will inevitably occur. Histological transformation is one of the causes of TKI resistance in NSCLC. Reports of ALK-rearranged adenocarcinoma with histological transformation are limited. A case of an invasive lung adenocarcinoma patient with ALK rearrangement who experienced histological transformation into sarcomatoid carcinoma after ALK TKI resistance is reported, and ALK fusion, MET amplification and TP53 mutation were detected after transformation. This case first reported a patient with invasive lung adenocarcinoma harboring ALK rearrangement who underwent histological transformation into sarcomatoid carcinoma after ALK TKI resistance, and MET amplification might represent the cause. After transformation, the patient benefited from targeted therapy combined with chemotherapy, which represents a promising option for patients with sarcomatoid carcinoma transformation.

Tackling Drug Resistance in EGFR Exon 20 Insertion Mutant Lung Cancer.

Insertion mutations in exon 20 (Ex20ins) of the epidermal growth factor receptor (EGFR) gene are the largest class of EGFR mutations in non-small cell lung cancer (NSCLC) for which there are currently no approved targeted therapies. NSCLC patients with these mutations do not respond to clinically approved EGFR tyrosine kinase inhibitors (TKIs) and have poor outcomes. A number of early phase clinical trials are currently underway to evaluate the efficacy of a new generation of TKIs that are capable of binding to and blocking Ex20ins. Although these agents have shown some clinical activity, patient responses have been restricted by dose-limiting toxicity or rapid acquisition of resistance after a short response. Here we review the current understanding of the mechanisms of resistance to these compounds, which include on-target EGFR secondary mutations, compensatory bypass pathway activation and acquisition of an EMT phenotype. Taking lessons from conventional EGFR inhibitor therapy in NSCLC, we also consider other potential sources of resistance including the presence of drug-tolerant persister cells. We will discuss therapeutic strategies which have the potential to overcome different forms of drug resistance. We conclude by evaluating recent technological developments in drug discovery such as PROTACs as a means to better tackle TKI resistance in NSCLC harbouring Ex20ins mutations.

Long Noncoding RNA LINC01116 Contributes to Gefitinib Resistance in Non-small Cell Lung Cancer through Regulating IFI44

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs), such as gefitinib, have been established as first-line treatments for non-small cell lung cancer (NSCLC) patients and have exhibited notable clinical efficacy. However, resistance to TKIs has become one of the major obstacles in improving the therapeutic efficacy of patients with NSCLC. This study aims to investigate the role of the long non-coding RNA (lncRNA) LINC01116 in gefitinib resistance of NSCLC and explore its underlying mechanism. In this study, we found that LINC01116 is upregulated in the gefitinib-resistant NSCLC cells and tissues. Loss- and gain-of-function assays uncovered that LINC01116 downregulation sensitized gefitinib resistance, whereas the overexpression of LINC01116 conferred PC9/R cells to gefitinib treatment. Moreover, LINC01116 silencing increased IFI44 expression. Overexpression of IFI44 reversed the resistance to gefitinib in PC9/R cells, and rescue experiments confirmed that LINC01116 affects the gefitinib resistance of PC9/R cells partly dependent on regulating IFI44 expression. Moreover, downregulation of LINC01116 increased the sensitivity of PC9/R cells to gefitinib in vivo. Our study demonstrates that LINC01116 plays a critical role in gefitinib resistance of NSCLC cells by affecting IFI44 expression, providing a novel therapeutic target to overcome TKI resistance in NSCLC.

Abstract 777: Down-regulation of miR-506 contributes to EGFR-TKI resistance through inducing sonic hedgehog signaling in non-small cell lung cancer

Abstract Background: Lung cancer is the leading cause of cancer related death in the United States. Epidermal Growth Factor Receptor (EGFR) mutation predicts response to a tyrosine kinase inhibitor (TKI) of EGFR in approximately 25% of patients. Non-small cell lung cancer (NSCLC) patients with EGFR mutation eventually develop resistance to EGFR-TKI. The mechanism of resistance is not fully elucidated but majority of the cases is related to emergence of clones with T790M mutation in EGFR, amplification of cMET and Epidermal Mesenchymal Transition (EMT). Sonic Hedgehog (SHh) signaling activation is involved in EMT through FGF, notch, TGFβ signaling and microRNA (miRs) networks. Several miRs have been shown to correlate with TKI resistance indicating that miRs may serve as novel targets and/or biomarkers for anti-EGFR therapy. MiR-506 is involved in Hedgehog signaling and it is abnormally expressed in several cancers. However, the role of miR-506 in modulating TKI resistance in NSCLC remains unexplored. In this study, we investigated the role of miR-506 in the regulation of SHh in EGFR-TKI-resistant lung cancer cell lines. Methods: To generate resistant cell lines, two EGFR-TKI sensitive NSCLC cells (HCC4006 and HCC827) were exposed to increasing concentrations of erlotinib up to 20 µM over 6 months. The resultant clones were verified for sensitivity to erlotinib using a crystal violet staining assay. The expression of miR-506 in parental and resistant clones was measured using Taqman microRNA assay. Invasive/migratory ability of parental and resistant clones was measured by Boyden chamber assays. EMT and stemness markers were evaluated by Western blotting. Results: The studies demonstrated that miR-506 levels were ~90% and 75% lower in most resistant clones of HCC4006 (HCC4006ER4) and HCC827 (HCC827ER3), respectively. These clones showed overexpression of SHh (5-fold in HCC4006ER4 and 2.5-fold in HCC827ER3 as compared to their respective parental cells). Ectopic expression of miR-506 in these resistant cells inhibits the expression of SHh by ~80% as well as its downstream mediator, GLI1 by 55%. Our results showed that the IC50 of erlotinib was 22.4 μM for ER cells transfected with ctrl-miR and 4.7 μM for cells with miR-506 mimics. Moreover, an epithelial marker, E-cadherin is upregulated (~2.7-fold) and mesenchymal/cancer stem cell markers (e.g., N-cadherin, vimentin, Sox-2, Notch1, CD44 and ALDH1A1) were significantly downregulated (75-90%, p-value<0.001) in miR-506 overexpressing cells. Conclusions: Our data showed that miR-506 downregulation and induction of SHh are associated with EGFR-TKI resistance in EGFR mutated NSCLC cells. MiR-506 interference and inhibition of SHh pathway may be potential therapeutic strategies to reverse resistance to EGFR-TKI in NSCLC with EGFR mutation. (This study was funded by the support from IRG-16-194-07(IH) and Godwin's lab). Citation Format: Inamul Haque, Mukut Sharma, Andrew K. Godwin, Chao H. Huang. Down-regulation of miR-506 contributes to EGFR-TKI resistance through inducing sonic hedgehog signaling in non-small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 777.

Activation of an AKT/FOXM1/STMN1 pathway drives resistance to tyrosine kinase inhibitors in lung cancer

Background:Tyrosine kinase inhibitors (TKIs) have demonstrated clinical benefits in the treatment of several tumour types. However, the emergence of TKI resistance restricts the therapeutic effect. This study uses non-small cell lung cancer (NSCLC) to explore the mechanisms contributing to TKI resistance in tumours.Methods:Biological phenotypes and RNA microarray expression data were analysed in NSCLC cells with and without TKI pretreatment. Specific inhibitors and siRNAs were used to validate the direct involvement of an AKT/FOXM1/STMN1 pathway in TKI resistance. Patients’ tissues were analysed to explore the clinical importance of FOXM1 and STMN1.Results:In vitro and in vivo studies showed that TKIs induced the enrichment of cancer stem cells (CSC), promoted epithelial to mesenchymal transition (EMT), and conferred multidrug resistance on NSCLC cells in a cell type- and TKI class-dependent manner. Mechanistically, TKIs activated an AKT/FOXM1/STMN1 pathway. The crucial role of this pathway in TKI-induced enrichment of CSC and drug resistance was verified by silencing FOXM1 and STMN1 or blocking the AKT pathway. Additionally, overexpression of STMN1 was associated with upregulation of FOXM1 in advanced NSCLC patients, and STMN1/FOXM1 upregulation predicted a poor outcome.Conclusions:Our findings elucidate an additional common mechanism for TKI resistance and provide a promising therapeutic target for reversing TKI resistance in NSCLC.

Mechanisms of Resistance to EGFR Tyrosine Kinase Inhibitors and Therapeutic Approaches: An Update.

Resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) in non small cell lung cancer (NSCLC) is mediated by two major mechanisms namely secondary mutation T790M in EGFR and cMET amplification. Other molecular mediators which contribute towards TKI resistance include the activation of compensatory growth signaling, epithelial mesenchymal transition and microRNAs regulating EGFR and cMET levels. In this chapter, we have included the major mechanisms which contribute towards EGFR TKI resistance in NSCLC. Several therapeutic approaches to overcome TKI resistance are also presented which include second and third generation EGFR TKI inhibitors and cMET inhibitors. Further, the rationale to utilize the combination therapies to simultaneously target EGFR and other major oncogene addictive pathway such as ERBB2 and AXL kinase is outlined. Another promising approach to overcome TKI resistance is to potentiate EGFR protein for degradation. These studies will best be utilized when we can identify the oncogene addictions in an individual patient and tailor the therapy/therapies accordingly for the maximum benefits.

Posttranslational modifications of FOXO1 regulate epidermal growth factor receptor tyrosine kinase inhibitor resistance for non-small cell lung cancer cells.

Epidermal growth factor receptor tyrosine kinase inhibitors (TKIs) are effective clinical therapies for advanced non-small cell lung cancer (NSCLC) patients, while resistance to TKIs remains a serious problem in clinical practice. Recently, it has been proposed that targeting mTOR could overcome TKI resistance in NSCLC cells. Forkhead box class O1 (FOXO1) has emerged as an important rheostat that modulates the activity of Akt and mTOR signaling pathway. However, the role of FOXO1 and related regulatory mechanism in TKI resistance in NSCLC remain largely unknown. Here, we find that mTOR-AKT-FOXO1 signaling cascade is deregulated in TKI-resistant NSCLC cells and that FOXO1 was highly phosphorylated and lowly acetylated upon erlotinib treatment. Combination of mTOR or PI3K inhibitor and erlotinib overcomes TKI resistance to inhibit cell growth and induce apoptosis in TKI-resistant NSCLC cells. Furthermore, the phosphorylation and acetylation of FOXO1 are reversely modulated by mTORC2-AKT signaling pathway. FOXO1 mutation analyses reveal that FOXO1 acetylation inhibits cell proliferation and promotes NSCLC cell apoptosis, while the phosphorylation of FOXO1 plays opposite roles in NSCLC cells. Importantly, increasing FOXO1 acetylation by a HDAC inhibitor, depsipeptide, overcomes TKI resistance to effectively induce TKI-resistant NSCLC cell apoptosis. Together, FOXO1 plays dual roles in TKI resistance through posttranslational modifications in NSCLC and this study provides a possible strategy for treatment of TKI-resistant NSCLC patients.

Histone Deacetylation, Instead of Promoter Methylation, Results in the Epigenetic Silencing of Bim and Resistance to Egfr Tki in Nsclc

ABSTRACT Aim: With targeted therapy improving the survival of advanced stage epidermal growth factor receptor (EGFR)-mutant non-small cell lung cancer (NSCLC) patients, resistannce remains a major issue in the application of EGFR tyrosine kinase inhibitors (TKIs). Bim, a Bcl-2 family pro-apoptotic protein, has been intensively studied for its role in various targeted therapies. Hence we investigated the epigenetic regulation of Bim in NSCLC cell lines and patients in the hope of identifying its relationship with EGFR TKI resistance. Methods: Methylation specific PCR, pyrosequencing and nested quantitative MSP (nested q-MSP) were applied to study the methylation status of BIM in NSCLC cell lines and the BIM methylation profile in NSCLC patients was assessed by nested q-MSP. PC9 and its gefitinib-resistant cell lines were treated with methylation inhibitor 5-aza-2′-deoxycytidine (AZA) and histone deacetylation inhibitor trichostatin A (TSA) before gefitinib treatment. Bim RNA level, cell survival and resistance to gefitinib were examined. The distribution of various levels of methylated BIM and their relationship with EGFR TKI efficacy was statistically analyzed. Results: 8 NSCLC cell lines all carried hypo-methylated BIM. AZA did not increase the expression of Bim in PC9 and its gefitinib-resistant cell lines, nor did it reverse their resistance to gefitinib. Instead, cells experienced less apoptosis from gefitinib when pre-treated with AZA. TSA on the other hand, not only increased the expression of Bim RNA significantly in the three cell lines, but also reversed their resistance to gefitinib. 25 (78.1%) patients with hypo-methylated BIM and 7 (21.9%) with partial or hyper-methylated BIM were identified. Hypo-methylated BIM distributed randomly in different clinicalpathological charcteristics. In both the entire study group and EGFR mutant group, hypo-methylated BIM carriers experienced no significant PFS difference compared with patients with partial or hyper-methylated BIM. Conclusions: All cell lines in the study and the majority of patients were with hypo-methylated BIM. AZA didn't reverse the resistance to EGFR TKI in acquired resistant cell lines PC9/R and PC9/G2, while HDACi TSA did. Thus histone deacetylation, rather than promoter methylation, may play a major role in the epigenetic silencing of BIM and leads to EGFR TKI resistance in NSCLC. Disclosure: All authors have declared no conflicts of interest.

Clinical Implications of High MET Gene Dosage in Non-Small Cell Lung Cancer Patients without Previous Tyrosine Kinase Inhibitor Treatment

Recently, two studies revealed that MET amplification was associated with secondary epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) resistance in non-small cell lung cancer (NSCLC) patients. But it remains uncertain whether MET amplification could be related to primary TKI resistance in NSCLC because of limited data. MET gene dosage of the tumor tissues from 208 NSCLC patients was investigated by real time quantitative polymerase chain reaction and compared with molecular and clinical features, including EGFR mutations, KRAS mutations, EGFR gene copy numbers, and patient survivals. Three copies were used as the cutoff. Among them, 25 patients were also evaluable for EGFR TKI responsiveness. The proportion of high MET gene dosage was 10.58% (22/208) with higher incidence in squamous cell carcinoma (11.86%) and smokers (16.18%), although the differences with adenocarcinoma and nonsmokers were nonsignificant. Coexisting EGFR mutations were identified, and the incidence (8.54%) was similar to wild type (12.0%). High MET gene dosage was significantly associated with higher tumor stage (stage I + II versus stage III + IV; p = 0.0254) and prior chemotherapy for stage III + IV adenocarcinoma patients (35.71% versus 7.41%; p = 0.0145) but not correlated with primary TKI resistance. Among the 155 surgically resectable patients (stage I to IIIA), high MET gene dosage was significantly associated with shorter median survival (21.0 months versus 47.1 months; p = 0.042) by univariate analysis. High MET gene dosage was not related to primary TKI resistance and the incidence was increased after chemotherapy, suggesting high MET gene dosage may also be related to chemotherapy resistance.