Hypoxia induces gefitinib resistance in non-small-cell lung cancer with both mutant and wild-type epidermal growth factor receptors

Mechanisms of resistance to tyrosine kinase inhibitor-targeted therapy and overcoming strategies

Tyrosine kinase inhibitor (TKI)-targeted therapy has revolutionized cancer treatment by selectively blocking specific signaling pathways crucial for tumor growth, offering improved outcomes with fewer side effects compared with conventional chemotherapy. However, despite their initial effectiveness, resistance to TKIs remains a significant challenge in clinical practice. Understanding the mechanisms underlying TKI resistance is paramount for improving patient outcomes and developing more effective treatment strategies. In this review, we explored various mechanisms contributing to TKI resistance, including on-target mechanisms and off-target mechanisms, as well as changes in the tumor histology and tumor microenvironment (intrinsic mechanisms). Additionally, we summarized current therapeutic approaches aiming at circumventing TKI resistance, including the development of next-generation TKIs and combination therapies. We also discussed emerging strategies such as the use of dual-targeted antibodies and PROteolysis Targeting Chimeras. Furthermore, we explored future directions in TKI-targeted therapy, including the methods for detecting and monitoring drug resistance during treatment, identification of novel targets, exploration of dual-acting kinase inhibitors, application of nanotechnologies in targeted therapy, and so on. Overall, this review provides a comprehensive overview of the challenges and opportunities in TKI-targeted therapy, aiming to advance our understanding of resistance mechanisms and guide the development of more effective therapeutic approaches in cancer treatment.

Mechanistic prediction and validation of Brevilin A Therapeutic effects in Lung Cancer

BACKGROUND

Traditional Chinese medicine (TCM) has been found widespread application in neoplasm treatment, yielding promising therapeutic candidates. Previous studies have revealed the anti-cancer properties of Brevilin A, a naturally occurring sesquiterpene lactone derived from Centipeda minima (L.) A.Br. (C. minima), a TCM herb, specifically against lung cancer. However, the underlying mechanisms of its effects remain elusive. This study employs network pharmacology and experimental analyses to unravel the molecular mechanisms of Brevilin A in lung cancer.

METHODS

The Batman-TCM, Swiss Target Prediction, Pharmmapper, SuperPred, and BindingDB databases were screened to identify Brevilin A targets. Lung cancer-related targets were sourced from GEO, Genecards, OMIM, TTD, and Drugbank databases. Utilizing Cytoscape software, a protein-protein interaction (PPI) network was established. Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), Gene set enrichment analysis (GSEA), and gene-pathway correlation analysis were conducted using R software. To validate network pharmacology results, molecular docking, molecular dynamics simulations, and in vitro experiments were performed.

RESULTS

We identified 599 Brevilin A-associated targets and 3864 lung cancer-related targets, with 155 overlapping genes considered as candidate targets for Brevilin A against lung cancer. The PPI network highlighted STAT3, TNF, HIF1A, PTEN, ESR1, and MTOR as potential therapeutic targets. GO and KEGG analyses revealed 2893 enriched GO terms and 157 enriched KEGG pathways, including the PI3K-Akt signaling pathway, FoxO signaling pathway, and HIF-1 signaling pathway. GSEA demonstrated a close association between hub genes and lung cancer. Gene-pathway correlation analysis indicated significant associations between hub genes and the cellular response to hypoxia pathway. Molecular docking and dynamics simulations confirmed Brevilin A's interaction with PTEN and HIF1A, respectively. In vitro experiments demonstrated Brevilin A-induced dose- and time-dependent cell death in A549 cells. Notably, Brevilin A treatment significantly reduced HIF-1α mRNA expression while increasing PTEN mRNA levels.

CONCLUSIONS

This study demonstrates that Brevilin A exerts anti-cancer effects in treating lung cancer through a multi-target and multi-pathway manner, with the HIF pathway potentially being involved. These results lay a theoretical foundation for the prospective clinical application of Brevilin A.

Evaluation of AMG510 Therapy on KRAS-Mutant Non-Small Cell Lung Cancer and Colorectal Cancer Cell Using a 3D Invasive Tumor Spheroid System under Normoxia and Hypoxia

A 3D tumor spheroid has been increasingly applied in pharmaceutical development for its simulation of the tumor structure and microenvironment. The embedded-culture of a tumor spheroid within a hydrogel microenvironment could help to improve the mimicking of in vivo cell growth and the development of 3D models for tumor invasiveness evaluation, which could enhance its drug efficiency prediction together with cell viability detection. NCI-H23 spheroids and CT-26 spheroids, from a non-small cell lung cancer and colorectal cancer cell line, respectively, together with extracellular matrix were generated for evaluating their sensitivity to AMG510 (a KRAS^G12C inhibitor) under normoxia and hypoxia conditions, which were created by an on-stage environmental chamber. Results demonstrated that NCI-H23, the KRAS^G12C moderate expression cell line, only mildly responded to AMG510 treatment in normal 2D and 3D cultures and could be clearly evaluated by our system in hypoxia conditions, while the negative control CT-26 (G12D-mutant) spheroid exhibited no significant response to AMG510 treatment. In summary, our system, together with a controlled microenvironment and imaging methodology, provided an easily assessable and effective methodology for 3D in vitro drug efficiency testing and screenings.

Overview of the multifaceted resistances toward EGFR-TKIs and new chemotherapeutic strategies in non-small cell lung cancer

The role of epidermal growth factor receptor (EGFR) in non-small cell lung cancer (NSCLC) has been vastly studied over the last decade. This has led to the rapid development of many generations of EGFR tyrosine kinase inhibitors (EGFR-TKIs). However, patients treated with third-generation TKIs (osimertinib, avitinib and rociletinib) targeting the EGFR T790M mutation have shown emerging resistances and relapses. Therefore, further molecular understanding of NSCLC mutations, bypass signalling, tumour microenvironment and the existence of cancer stem cells to overcome such resistances is warranted. This will pave the way for designing novel and effective chemotherapies to improve patients' overall survival. In this review, we provide an overview of the multifaceted mechanism of resistances towards EGFR-TKIs, as well as the challenges and perspectives that should be addressed in strategising chemotherapeutic treatments to overcome the ever evolving and adaptive nature of NSCLC.

Triple therapy with osimertinib, bevacizumab and cetuximab in EGFR-mutant lung cancer with HIF-1α/TGF-α expression

Osimertinib, a third generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor, is the standard treatment for patients with lung cancer harboring EGFR T790M; however, acquired resistance is inevitable due to genetic and epigenetic changes in cancer cells. In addition, a recent randomized clinical trial revealed that the combination of osimertinib and bevacizumab failed to exhibit superior progression-free survival compared with osimertinib alone. The present study aimed to investigate the effect of triple therapy with osimertinib, bevacizumab and cetuximab in xenograft tumors with different initial tumor volumes (conventional model, 200 mm3 and large model, 500 mm3). The results demonstrated that osimertinib significantly inhibited tumor growth in both the conventional and large models; however, maximum tumor regression was attenuated in the large model in which hypoxia-inducible factor-1α (HIF-1α) and transforming growth factor-α (TGF-α) expression levels increased. Although the combination of osimertinib and bevacizumab exerted a greater inhibitory effect on tumor growth compared with osimertinib in the conventional model, the effect of this combination therapy was attenuated in the large model. TGF-α attenuated sensitivity to osimertinib in vitro; however, this negative effect was counteracted by the combination of osimertinib and cetuximab, but not osimertinib and bevacizumab. In the large xenograft tumor model, the triple therapy induced the greatest inhibitory effect on tumor growth compared with osimertinib alone and its combination with bevacizumab. Clinical trials of the triple therapy are required for patients with lung cancer with EGFR mutations and HIF-1α/TGF-α.

SIRT1/PGC-1α/PPAR-γ Correlate With Hypoxia-Induced Chemoresistance in Non-Small Cell Lung Cancer

Resistance is the major cause of treatment failure and disease progression in non-small cell lung cancer (NSCLC). There is evidence that hypoxia is a key microenvironmental stress associated with resistance to cisplatin, epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs), and immunotherapy in solid NSCLCs. Numerous studies have contributed to delineating the mechanisms underlying drug resistance in NSCLC; nevertheless, the mechanisms involved in the resistance associated with hypoxia-induced molecular metabolic adaptations in the microenvironment of NSCLC remain unclear. Studies have highlighted the importance of posttranslational regulation of molecular mediators in the control of mitochondrial function in response to hypoxia-induced metabolic adaptations. Hypoxia can upregulate the expression of sirtuin 1 (SIRT1) in a hypoxia-inducible factor (HIF)-dependent manner. SIRT1 is a stress-dependent metabolic sensor that can deacetylate some key transcriptional factors in both metabolism dependent and independent metabolic pathways such as HIF-1α, peroxisome proliferator-activated receptor gamma (PPAR-γ), and PPAR-gamma coactivator 1-alpha (PGC-1α) to affect mitochondrial function and biogenesis, which has a role in hypoxia-induced chemoresistance in NSCLC. Moreover, SIRT1 and HIF-1α can regulate both innate and adaptive immune responses through metabolism-dependent and -independent ways. The objective of this review is to delineate a possible SIRT1/PGC-1α/PPAR-γ signaling-related molecular metabolic mechanism underlying hypoxia-induced chemotherapy resistance in the NSCLC microenvironment. Targeting hypoxia-related metabolic adaptation may be an attractive therapeutic strategy for overcoming chemoresistance in NSCLC.

Hypoxia in Lung Cancer Management: A Translational Approach

Simple Summary

Hypoxia is a common feature of lung cancers. Nonetheless, no guidelines have been established to integrate hypoxia-associated biomarkers in patient management. Here, we discuss the current knowledge and provide translational novel considerations regarding its clinical detection and targeting to improve the outcome of patients with non-small-cell lung carcinoma of all stages.

Abstract

Lung cancer represents the first cause of death by cancer worldwide and remains a challenging public health issue. Hypoxia, as a relevant biomarker, has raised high expectations for clinical practice. Here, we review clinical and pathological features related to hypoxic lung tumours. Secondly, we expound on the main current techniques to evaluate hypoxic status in NSCLC focusing on positive emission tomography. We present existing alternative experimental approaches such as the examination of circulating markers and highlight the interest in non-invasive markers. Finally, we evaluate the relevance of investigating hypoxia in lung cancer management as a companion biomarker at various lung cancer stages. Hypoxia could support the identification of patients with higher risks of NSCLC. Moreover, the presence of hypoxia in treated tumours could help clinicians predict a worse prognosis for patients with resected NSCLC and may help identify patients who would benefit potentially from adjuvant therapies. Globally, the large quantity of translational data incites experimental and clinical studies to implement the characterisation of hypoxia in clinical NSCLC management.

2-Methoxyestradiol synergizes with Erlotinib to suppress hepatocellular carcinoma by disrupting the PLAGL2-EGFR-HIF-1/2α signaling loop

Erlotinib, an EGFR tyrosine kinase inhibitor has been introduced into cancer chemotherapy. However, the therapeutic effects of erlotinib in hepatocellular carcinoma (HCC) remain vaguely understood. Our previous study found that a hypoxia-mediated PLAGL2-EGFR-HIF-1/2α signaling loop in HCC decreased response to erlotinib. The current study has demonstrated that the combination of erlotinib and 2ME2 exerted synergistic antitumor effects against HCC. Further investigation showed that erlotinib increased the expression level of EGFR, HIF-2α, and PLAGL2, which contributes to the insensitivity of hypoxic HCC cells to erlotinib. The simultaneous exposure to 2ME2 effectively inhibited the expression level of EGFR, HIF-2α, and PLAGL2 that was induced by erlotinib. This contributes to the synergistic effect of the two therapeutic agents. Furthermore, the combination of erlotinib and 2ME2 induced apoptosis and inhibited the stemness of hypoxic HCC cells. Our findings potentially explain the mechanism of HCC insensitivity to erlotinib and provide a new strategy of combining EGFR and HIF1/2α inhibitors for HCC treatment.

Hypoxia-Induced FAM13A Regulates the Proliferation and Metastasis of Non-Small Cell Lung Cancer Cells

Hypoxia in non-small cell lung cancer (NSCLC) affects cancer progression, metastasis and metabolism. We previously showed that FAM13A was induced by hypoxia in NSCLC but the biological function of this gene has not been fully elucidated. This study aimed to investigate the role of hypoxia-induced FAM13A in NSCLC progression and metastasis. Lentiviral shRNAs were used for FAM13A gene silencing in NSCLC cell lines (A549, CORL-105). MTS assay, cell tracking VPD540 dye, wound healing assay, invasion assay, BrdU assay and APC Annexin V staining assays were performed to examine cell proliferation ability, migration, invasion and apoptosis rate in NSCLC cells. The results of VPD540 dye and MTS assays showed a significant reduction in cell proliferation after FAM13A knockdown in A549 cells cultured under normal and hypoxia (1% O₂) conditions (p < 0.05), while the effect of FAM13A downregulation on CORL-105 cells was observed after 96 h exposition to hypoxia. Moreover, FAM13A inhibition induced S phase cell cycle arrest in A549 cells under hypoxia conditions. Silencing of FAM13A significantly suppressed migration of A549 and CORL-105 cells in both oxygen conditions, especially after 72 and 96 h (p < 0.001 in normoxia, p < 0.01 after hypoxia). It was showed that FAM13A reduction resulted in disruption of the F-actin cytoskeleton altering A549 cell migration. Cell invasion rates were significantly decreased in A549 FAM13A depleted cells compared to controls (p < 0.05), mostly under hypoxia. FAM13A silencing had no effect on apoptosis induction in NSCLC cells. In the present study, we found that FAM13A silencing has a negative effect on proliferation, migration and invasion activity in NSCLC cells in normal and hypoxic conditions. Our data demonstrated that FAM13A depleted post-hypoxic cells have a decreased cell proliferation ability and metastatic potential, which indicates FAM13A as a potential therapeutic target in lung cancer.

Quantitative Proteomic Approach Reveals Altered Metabolic Pathways in Response to the Inhibition of Lysine Deacetylases in A549 Cells under Normoxia and Hypoxia

Growing evidence is showing that acetylation plays an essential role in cancer, but studies on the impact of KDAC inhibition (KDACi) on the metabolic profile are still in their infancy. Here, we analyzed, by using an iTRAQ-based quantitative proteomics approach, the changes in the proteome of KRAS-mutated non-small cell lung cancer (NSCLC) A549 cells in response to trichostatin-A (TSA) and nicotinamide (NAM) under normoxia and hypoxia. Part of this response was further validated by molecular and biochemical analyses and correlated with the proliferation rates, apoptotic cell death, and activation of ROS scavenging mechanisms in opposition to the ROS production. Despite the differences among the KDAC inhibitors, up-regulation of glycolysis, TCA cycle, oxidative phosphorylation and fatty acid synthesis emerged as a common metabolic response underlying KDACi. We also observed that some of the KDACi effects at metabolic levels are enhanced under hypoxia. Furthermore, we used a drug repositioning machine learning approach to list candidate metabolic therapeutic agents for KRAS mutated NSCLC. Together, these results allow us to better understand the metabolic regulations underlying KDACi in NSCLC, taking into account the microenvironment of tumors related to hypoxia, and bring new insights for the future rational design of new therapies.

Nanomedicine of tyrosine kinase inhibitors

Recent progress in nanomedicine and targeted therapy brings new breeze into the field of therapeutic applications of tyrosine kinase inhibitors (TKIs). These drugs are known for many side effects due to non-targeted mechanism of action that negatively impact quality of patients' lives or that are responsible for failure of the drugs in clinical trials. Some nanocarrier properties provide improvement of drug efficacy, reduce the incidence of adverse events, enhance drug bioavailability, helps to overcome the blood-brain barrier, increase drug stability or allow for specific delivery of TKIs to the diseased cells. Moreover, nanotechnology can bring new perspectives into combination therapy, which can be highly efficient in connection with TKIs. Lastly, nanotechnology in combination with TKIs can be utilized in the field of theranostics, i.e. for simultaneous therapeutic and diagnostic purposes. The review provides a comprehensive overview of advantages and future prospects of conjunction of nanotransporters with TKIs as a highly promising approach to anticancer therapy.

PLGA Nanofiber/PDMS Microporous Composite Membrane-Sandwiched Microchip for Drug Testing

Lung-on-a-chip devices could provide new strategies for a biomimetic lung cell microenvironment and construction of lung disease models in vitro, and are expected to greatly promote the development of drug evaluation, toxicological detection, and disease model building. In this study, we developed a novel poly (lactic-co-glycolic acid) (PLGA) nanofiber/polydimethylsiloxane (PDMS) microporous composite membrane-sandwiched lung-on-a-chip to perform anti-tumor drug testing. The composite membrane was characterized, and the results showed that it was permeable to molecules and thus could be used to study small-molecule drug diffusion. In addition, the microchip could apply perfusion fluids to simulate blood flow under extremely low fluid shear stress, and could also simulate the spherical-like shape of the alveoli by deformation of the composite membrane. Using this chip, we evaluated the anti-tumor drug efficacy of gefitinib in two kinds of non-small cell lung cancer cells, the lung adenocarcinoma NCI-H1650 cell line and the large cell lung cancer NCI-H460 cell line. We further probed the resistance of NCI-H460 cells to gefitinib under normoxic and hypoxic conditions. The established composite membrane-sandwiched lung chip can simulate more biochemical and biophysical factors in the lung physiological and pathological microenvironment, and it has important applications in the personalized treatment of lung tumors. It is expected to play a potential role in clinical diagnosis and drug screening.

Long non-coding RNAs in lung cancer: implications for lineage plasticity-mediated TKI resistance

The efficacy of targeted therapy in non-small-cell lung cancer (NSCLC) has been impeded by various mechanisms of resistance. Besides the mutations in targeted oncogenes, reversible lineage plasticity has recently considered to play a role in the development of tyrosine kinase inhibitors (TKI) resistance in NSCLC. Lineage plasticity enables cells to transfer from one committed developmental pathway to another, and has been a trigger of tumor adaptation to adverse microenvironment conditions including exposure to various therapies. More importantly, besides somatic mutation, lineage plasticity has also been proposed as another source of intratumoural heterogeneity. Lineage plasticity can drive NSCLC cells to a new cell identity which no longer depends on the drug-targeted pathway. Histological transformation and epithelial–mesenchymal transition are two well-known pathways of lineage plasticity-mediated TKI resistance in NSCLC. In the last decade, increased re-biopsy practice upon disease recurrence has increased the recognition of lineage plasticity induced resistance in NSCLC and has improved our understanding of the underlying biology. Long non-coding RNAs (lncRNAs), the dark matter of the genome, are capable of regulating variant malignant processes of NSCLC like the invisible hands. Recent evidence suggests that lncRNAs are involved in TKI resistance in NSCLC, particularly in lineage plasticity-mediated resistance. In this review, we summarize the mechanisms of lncRNAs in regulating lineage plasticity and TKI resistance in NSCLC. We also discuss how understanding these themes can alter therapeutic strategies, including combination therapy approaches to overcome TKI resistance.

Potential monoamine oxidase A inhibitor suppressing paclitaxel-resistant non-small cell lung cancer metastasis and growth

BACKGROUND

High expression of monoamine oxidase A (MAOA) in non-small cell lung cancer (NSCLC) is related to epithelial-mesenchymal transition (EMT) and the development of clinicopathological features of NSCLC. Nevertheless, the role of MAOA in drug resistance still remains unclear. Hence, the aim of this article was to evaluate a previously synthesized MAOA inhibitor (G11) on inhibiting paclitaxel-resistant NSCLC metastasis and growth.

METHODS

First, MAOA expression level was evaluated in several NSCLC cell lines. An MTT assay was used to validate the inhibitory effect of G11 on NSCLC cells in vitro. Second, gene expression in G11-treated H460/PTX cells was analyzed by microarray gene expression. Third, transwell assay was performed to assess the invasion and metastasis of G11-treated A549/PTX and H460/PTX cells and western blot assay used to analyze vital protein expression level in G11-treated H460/PTX cells. Finally, the antimetastatic effect of G11 was tested in an NSCLC in vivo model.

RESULTS

Our data revealed that G11 significantly inhibited the viability of paclitaxel (PTX)-resistant NSCLC cell lines (A549/PTX and H460/PTX). G11 dramatically reduced the expression of MAOA in A549/PTX and H460/PTX cells, which exhibited relatively high MAOA expression levels. Additionally, G11 was found to hinder A549/PTX and H460/PTX cell migration and invasion. Furthermore, the in vivo study indicated that the coadministration of G11 and paclitaxel significantly suppressed tumor metastasis in H460/PTX lung metastasis models.

CONCLUSIONS

These findings indicated G11 showed a moderate inhibitory effect on paclitaxel-resistant NSCLC metastasis and growth, and support further investigation on MAOA potentially as a promising therapeutic target for paclitaxel-resistant NSCLC treatment.

KEY POINTS

SIGNIFICANT FINDINGS OF THE STUDY: Inhibition of MAOA might contribute to the suppression of metastasis and growth in PTX-resistant NSCLC cells. What this study adds This study explored the potential function of MAOA in drug-resistant NSCLC and might consider MAOA as a promising target for the treatment of drug-resistant NSCLC.

Targeting Hypoxia Sensitizes TNBC to Cisplatin and Promotes Inhibition of Both Bulk and Cancer Stem Cells

Development of targeted therapies for triple-negative breast cancer (TNBC) is an unmet medical need. Cisplatin has demonstrated its promising potential for the treatment of TNBC in clinical trials; however, cisplatin treatment is associated with hypoxia that, in turn, promotes cancer stem cell (CSC) enrichment and drug resistance. Therapeutic approaches to attenuate this may lead to increased cisplatin efficacy in the clinic for the treatment of TNBC. In this report we analyzed clinical datasets of TNBC and found that TNBC patients possessed higher levels of EGFR and hypoxia gene expression. A similar expression pattern was also observed in cisplatin-resistant ovarian cancer cells. We, thus, developed a new therapeutic approach to inhibit EGFR and hypoxia by combination treatment with metformin and gefitinib that sensitized TNBC cells to cisplatin and led to the inhibition of both CD44+/CD24− and ALDH+ CSCs. We demonstrated a similar inhibition efficacy on organotypic cultures of TNBC patient samples ex vivo. Since these drugs have already been used frequently in the clinic; this study illustrates a novel, clinically translatable therapeutic approach to treat patients with TNBC.

GLI1 activation is a key mechanism of erlotinib resistance in human non-small cell lung cancer

Lung cancer is the leading cause of cancer-associated death worldwide. In recent years, the advancement of epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) targeted therapies has provided clinical benefits for lung cancer patients with EGFR mutations. The response to EGFR-TKI varies in patients with lung cancer, and resistance typically develops during the course of the treatment. Therefore, understanding biomarkers which can predict resistance to EGFR-TKI is important. Overexpression of GLI causes activation of the Hedgehog (Hh) signaling pathway and plays a critical role in oncogenesis in numerous types of cancer. In the present study, the role of GLI1 in erlotinib resistance was investigated. GLI1 mRNA and protein expression levels were determined using reverse transcription-quantitative PCR and immunohistochemistry (IHC) in lung cancer cell lines and tumor specimens, respectively. GLI1 mRNA expression levels were found to be positively correlated with the IC₅₀ of erlotinib in 15 non-small cell lung cancer (NSCLC) cell lines. The downregulation of GLI1 using siRNA sensitized lung cancer cells to the erlotinib treatment, whereas the overexpression of GLI1 increased the survival of lung cancer cells in the presence of erlotinib, indicating that Hh/GLI activation may play a critical role in the development of TKI resistance in lung cancer. Combined treatment with erlotinib and a GLI1 inhibitor reduced the cell viability synergistically. A retrospective study of patients with NSCLC treated with erlotinib revealed that those with a high IHC score for GLI1 protein expression had a poorer prognosis. These results indicated that GLI1 is a key regulator for TKI sensitivity, and patients with lung cancer may benefit from the combined treatment of TKI and GLI1 inhibitor.

Novel drugs targeting EGFR and HER2 exon 20 mutations in metastatic NSCLC

Approximately 4% of epidermal growth factor receptor (EGFR)-mutated non-small cell lung cancer (NSCLC) present EGFR exon 20 in-frame insertions, accounting for 0.3 %-3.7 % of NSCLC. In addition, 2 %-4 % of patients with NSCLC harbor human epidermal growth factor receptor 2 gene (HER2) mutations, being the 90 % of them exon 20 insertions. These mutations confer intrinsic resistance to available EGFR tyrosine kinase inhibitors (TKIs) and anti-HER2 treatments, as they result in steric hindrance of the drug-binding pocket. Therefore, no targeted therapies have been approved for NSCLC patients with EGFR or HER2 exon 20- activating mutations to date and remain an unmet clinical need. Promising efforts to novel treatment development have been made. Early data provide encouraging activity of novel drugs targeting EGFR and HER2 mutations in metastatic NSCLC. In this review we will summarize all the data reported to date about these driver molecular alterations and potential targeted therapies.

Advances in nanotechnology-based delivery systems for EGFR tyrosine kinases inhibitors in cancer therapy

Oral tyrosine kinase inhibitors (TKIs) against epidermal growth factor receptor (EGFR) family have been introduced into the clinic to treat human malignancies for decades. Despite superior properties of EGFR-TKIs as small molecule targeted drugs, their applications are still restricted due to their low solubility, capricious oral bioavailability, large requirement of daily dose, high binding tendency to plasma albumin and initial/acquired drug resistance. Nanotechnology is a promising tool to improve efficacy of these drugs. Through non-oral routes. Various nanotechnology-based delivery approaches have been developed for providing efficient delivery of EGFR-TKIs with a better pharmacokinetic profile and tissue-targeting ability. This review aims to indicate the advantage of nanocarriers for EGFR-TKIs delivery.

Vasodilator oxyfedrine inhibits aldehyde metabolism and thereby sensitizes cancer cells to xCT-targeted therapy

The major cellular antioxidant glutathione (GSH) protects cancer cells from oxidative damage that can lead to the induction of ferroptosis, an iron‐dependent form of cell death triggered by the aberrant accumulation of lipid peroxides. Inhibitors of the cystine‐glutamate antiporter subunit xCT, which mediates the uptake of extracellular cystine and thereby promotes GSH synthesis, are thus potential anticancer agents. However, the efficacy of xCT‐targeted therapy has been found to be diminished by metabolic reprogramming that affects redox status in cancer cells. Identification of drugs for combination with xCT inhibitors that are able to overcome resistance to xCT‐targeted therapy might thus provide the basis for effective cancer treatment. We have now identified the vasodilator oxyfedrine (OXY) as a sensitizer of cancer cells to GSH‐depleting agents including the xCT inhibitor sulfasalazine (SSZ). Oxyfedrine contains a structural motif required for covalent inhibition of aldehyde dehydrogenase (ALDH) enzymes, and combined treatment with OXY and SSZ was found to induce accumulation of the cytotoxic aldehyde 4‐hydroxynonenal and cell death in SSZ‐resistant cancer cells both in vitro and in vivo. Microarray analysis of tumor xenograft tissue showed cyclooxygenase‐2 expression as a potential biomarker for the efficacy of such combination therapy. Furthermore, OXY‐mediated ALDH inhibition was found to sensitize cancer cells to GSH depletion induced by radiation therapy in vitro. Our findings thus establish a rationale for repurposing of OXY as a sensitizing drug for cancer treatment with agents that induce GSH depletion.

Activation of insulin-like growth factor-1 receptor confers acquired resistance to osimertinib in non-small cell lung cancer with EGFR T790M mutation

Background

Osimertinib (AZD9291) is a third‐generation EGFR‐tyrosine kinase inhibitor (TKI) that selectively inhibits the activating EGFR mutation and T790M mutation, and is currently used globally to treat EGFR‐mutant non‐small cell lung cancer (NSCLC). However, acquired resistance to osimertinib is inevitable.

Methods

We established osimertinib‐resistant cells (PC9/T790M/AZDR and H1975/AZDR) derived from EGFR‐mutant NSCLC cells harboring T790M mutation, and investigated the mechanism of acquired resistance to osimertinib by whole‐exome sequencing and multiple phospho‐receptor tyrosine kinase (RTK) array. A tumor specimen from an EGFR‐mutant NSCLC patient with acquired resistance to osimertinib was also subjected to immunohistochemical analysis.

Results

Whole‐exome sequencing analysis demonstrated that genetic alterations, such as acquisition of EGFR C797S, loss of T790M mutation, MET amplification, or mutated KRAS, MEK, BRAF, PIK3CA, were not detected. Analysis of phospho‐RTK array revealed that insulin‐like growth factor‐1 receptor (IGF1R) was activated in PC9/T790M/AZDR and H1975/AZDR cells. Knockdown of IGF1R by siRNA as well as inhibition of IGF1R activation by linstinib (IGF1R inhibitor) significantly restored the sensitivity to osimertinib. Immunohistochemical analysis revealed that the expression level of phosphorylated IGF1R was higher in the tumor specimen from the EGFR‐mutant NSCLC patient with acquired resistance to osimertinib than in the specimen collected prior to the treatment.

Conclusions

IGF1R activation could occur following treatment with osimertinib in EGFR‐mutant NSCLC with T790M mutation, and might be one of the mechanisms underlying osimertinib resistance. Combined treatment of osimertinib and IGF1R inhibitor might be effective in overcoming the acquired resistance to osimertinib induced by IGF1R activation.

Key points

Significant findings of the study: Using osimertinib‐resistant cells, we found that IGF1R activation induced by osimertinib treatment in EGFR‐mutant NSCLC with T790M mutation is involved in resistance. Increased phosphorylation of IGF1R was observed in the tumor specimen from an EGFR‐mutant NSCLC patient with acquired osimertinib resistance.

What this study adds: IGF1R activation might be one of the mechanisms of osimertinib resistance. A combination therapy with osimertinib and an IGF1R inhibitor might be an optimal approach for overcoming the acquired resistance to osimertinib induced by IGF1R activation.

ΗΙF1α, EGR1 and SP1 co-regulate the erythropoietin receptor expression under hypoxia: an essential role in the growth of non-small cell lung cancer cells

BACKGROUND

Overexpression of erythropoietin (EPO) and EPO receptor (EPO-R) is associated with poor prognosis in non-small-cell lung carcinoma (NSCLC). Hypoxia, a potent EPO inducer, is a major stimulating factor in the growth of solid tumors. However, how EPO-R expression is regulated under hypoxia is largely unknown.

METHODS

The role of EPO-R in NSCLC cell proliferation was assessed by RNA interference in vitro. Luciferase reporter assays were performed to map the promoter elements involved in the EPO-R mRNA transcription. Nuclear co-immunoprecipitation and chromatin immunoprecipitation were performed to assess the interaction among transcription factors HIF1α, SP1, and EGR1 in the regulation of EPO-R under hypoxia. The expression of key EPO-R transcription factors in clinical specimens were determined by immunohistochemistry.

RESULTS

Hypoxia induced a dosage and time dependent EPO-R mRNA expression in NSCLC cells. Knockdown of EPO-R reduced NSCLC cell growth under hypoxia (P < 0.05). Mechanistically, a SP1-EGR1 overlapped DNA binding sequence was essential to the hypoxia induced EPO-R transcription. In the early phase of hypoxia, HIF1α interacted with EGR1 that negatively regulated EPO-R. With the exit of EGR1 in late phase, HIF1α positively regulated EPO-R expression through additive interaction with SP1. In clinical NSCLC specimen, SP1 was positively while EGR1 was negatively associated with active EPO-R expression (P < 0.05).

CONCLUSIONS

HIF1α, SP1 and EGR1 mediated EPO-R expression played an essential role in hypoxia-induced NSCLC cell proliferation. Our study presents a novel mechanism of EPO-R regulation in the tumor cells, which may provide information support for NSCLC diagnosis and treatment.

Role of FBXW7 in the quiescence of gefitinib-resistant lung cancer stem cells in EGFR-mutant non-small cell lung cancer

Several recent studies suggest that cancer stem cells (CSCs) are involved in intrinsic resistance to cancer treatment. Maintenance of quiescence is crucial for establishing resistance of CSCs to cancer therapeutics. F-box/WD repeat-containing protein 7 (FBXW7) is a ubiquitin ligase that regulates quiescence by targeting the c-MYC protein for ubiquitination. We previously reported that gefitinib-resistant persisters (GRPs) in EGFR-mutant non-small cell lung cancer (NSCLC) cells highly expressed octamer-binding transcription factor 4 (Oct-4) as well as the lung CSC marker CD133, and they exhibited distinctive features of the CSC phenotype. However, the role of FBXW7 in lung CSCs and their resistance to epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors in NSCLC is not fully understood. In this study, we developed GRPs from the two NSCLC cell lines PC9 and HCC827, which express an EGFR exon 19 deletion mutation, by treatment with a high concentration of gefitinib. The GRPs from both PC9 and HCC827 cells expressed high levels of CD133 and FBXW7, but low levels of c-MYC. Cell cycle analysis demonstrated that the majority of GRPs existed in the G0/G1 phase. Knockdown of the FBXW7 gene significantly reduced the cell number of CD133-positive GRPs and reversed the cell population in the G0/G1-phase. We also found that FBXW7 expression in CD133-positive cells was increased and c-MYC expression was decreased in gefitinib-resistant tumors of PC9 cells in mice and in 9 out of 14 tumor specimens from EGFR-mutant NSCLC patients with acquired resistance to gefitinib. These findings suggest that FBXW7 plays a pivotal role in the maintenance of quiescence in gefitinib-resistant lung CSCs in EGFR mutation-positive NSCLC.

Characterization of Hypoxia-associated Molecular Features to Aid Hypoxia-Targeted Therapy

Tumor hypoxia is a major contributor to resistance to anti-cancer therapies. Given that the results of hypoxia-targeted therapy trials have been disappointing, a more personalized approach may be needed. Here we characterize multi-OMIC molecular features associated with tumor hypoxia and identify molecular alterations that correlate with both drug-resistant and drug-sensitive responses to anti-cancer drugs. Based on a well-established hypoxia gene expression signature, we classify about 10,000 tumor samples into hypoxia score-high and score-low groups across different cancer types from The Cancer Genome Atlas and demonstrate their prognostic associations. We then identify various types of molecular features associated with hypoxia status that correlate with drug resistance but, in some cases, also with drug sensitivity, contrasting the conventional view that hypoxia confers drug resistance. We further show that 110 out of 121 (90.9%) clinically actionable genes can be affected by hypoxia status and experimentally validate the predicted effects of hypoxia on the response to several drugs in cultured cells. Our study provides a comprehensive molecular-level understanding of tumor hypoxia and may have practical implications for clinical cancer therapy.

Apigenin Combined With Gefitinib Blocks Autophagy Flux and Induces Apoptotic Cell Death Through Inhibition of HIF-1α, c-Myc, p-EGFR, and Glucose Metabolism in EGFR L858R+T790M-Mutated H1975 Cells

Cancer cells are characterized by abnormally increased glucose uptake and active bio-energy and biosynthesis to support the proliferation, metastasis, and drug resistant survival. We examined the therapeutic value of the combination of apigenin (a natural small-molecule inhibitor of Glut1 belonging to the flavonoid family) and gefitinib on epidermal growth factor receptor (EGFR)-resistant mutant non-small cell lung cancer, to notably damage glucose utilization and thus suppress cell growth and malignant behavior. Here, we demonstrate that apigenin combined with gefitinib inhibits multiple oncogenic drivers such as c-Myc, HIF-1α, and EGFR, reduces Gluts and MCT1 protein expression, and inactivates the 5' adenosine monophosphate-activated protein kinase (AMPK) signaling, which regulates glucose uptake and maintains energy metabolism, leading to impaired energy utilization in EGFR L858R-T790M-mutated H1975 lung cancer cells. H1975 cells exhibit dysregulated metabolism and apoptotic cell death following treatment with apigenin + gefitinib. Therefore, the combined apigenin + gefitinib treatment presents an attractive strategy as alternative treatment for the acquired resistance to EGFR-TKIs in NSCLC.

Targeting EGFR exon 20 insertion mutations in non-small cell lung cancer

Inframe insertions of three or more base pairs in exon 20 of the epidermal growth factor receptor (EGFR) gene were among the first EGFR mutations to be identified as oncogenic drivers in non-small cell lung cancer (NSCLC). However, unlike the classical EGFR L858R point mutation or exon 19 deletions, which represent the majority of EGFR mutations in NSCLC, low frequency EGFR exon 20 insertion mutations are associated with de novo resistance to targeted EGFR inhibitors and correlate with a poor patient prognosis. Here, we review the developments over the last 5 years in which pre-clinical studies, including elucidation of the crystal structure of an EGFR exon 20 insertion mutant kinase, have revealed a unique mechanism of kinase activation and steric conformation that define the lack of response of these EGFR mutations to clinically approved EGFR inhibitors. The recent development of several novel small molecule compounds that selectively inhibit EGFR exon 20 insertions holds promise for future therapeutic options that will be effective for patients with this molecular subtype of NSCLC.

Larger tumors are associated with inferior progression-free survival of first-line EGFR-tyrosine kinase inhibitors and a lower abundance of EGFR mutation in patients with advanced non-small cell lung cancer

BACKGROUND

The impact of primary tumor size on the therapeutic outcomes of EGFR-tyrosine kinase inhibitors (TKIs) in advanced non-small cell lung cancer (NSCLC) with EGFR mutation remains unclear.

METHODS

A total of 291 consecutive patients with advanced EGFR-mutant NSCLC administered first-line EGFR-TKIs were enrolled. Computed tomography was used to assess primary tumor diameter. The amplification refractory mutation system plus was used to quantitatively evaluate the abundance of EGFR mutations. Associations between depth of response, abundance of EGFR mutations, and tumor size was investigated.

RESULTS

Patients were divided into three groups according to T classification: ≤ 3 cm (n = 109), 3-5 cm (n = 121), and > 5 cm (n = 61). Median progression-free survival (PFS) was significantly longer in the ≤ 3 cm and 3-5 cm groups compared to the > 5 cm group (10.8 vs. 10.5 vs. 7.1 months; P < 0.001). Subgroup analysis revealed a consistent result in patients with exon 19 deletion and 21 L858R mutation. Multivariate analysis revealed that tumor size was an independent predictive factor for PFS (hazard ratio 1.528, 95% confidence interval 1.104-2.115; P = 0.010). Larger tumors (> 5 cm) were marginally significantly less EGFR-mutant abundant than smaller tumors (≤ 5 cm) (mean ± standard deviation 30.5 ± 29.5% vs. 45.8 ± 43.1%; P = 0.08).

CONCLUSION

Larger tumors (> 5 cm) were associated with inferior PFS of first-line EGFR-TKI therapy in advanced NSCLC patients with activating EGFR mutations. A potential explaination might be that EGFR mutations are less abundant in larger tumors.

Hypoxia-inducible factor-1 signaling pathway influences the sensitivity of HCC827 cells to gefitinib

The majority of patients with non-small cell lung cancer (NSCLC) with activating epidermal growth factor receptor (EGFR) mutations inevitably progress in stage despite an initial substantial and rapid response to EGFR-tyrosine kinase inhibitors (EGFR-TKIs). Previous research indicates that hypoxia may be associated with resistance to EGFR-TKIs in EGFR mutation-positive NSCLC. Therefore, the present study regulated the activity of hypoxia-inducible factor-1 (HIF-1) signaling pathway to observe if it is able to alter the sensitivity of lung cancer cells to gefitinib. The present study selected 3-(5'-hydroxymethyl-2'-furyl)-1-benzylindazole (YC-1) and dimethyloxalylglycine (DMOG) as a HIF-1 signaling pathway inhibitor and activator, respectively, on HCC827 cells. Cells were incubated with different treatments for different durations: A blank control, DMOG, gefitinib, or DMOG and gefitinib combined, for 36 and 48 h; and then a blank control, YC-1, gefitinib, or YC-1 and gefitinib combined, for 16 and 28 h. A western blot analysis assay was performed to evaluate the protein expression levels of HIF-1α and phosphorylated hepatocyte growth factor receptor (p-MET), an MTT assay was used to determine cell proliferation, a colony formation assay was used to investigate the colony-forming ability and a wound healing assay was used to test the cell migration ability. Additionally, Pearson's correlation analysis was used to evaluate the correlation between p-Met and HIF-1α expression levels. Finally, it was identified that gefitinib and DMOG combined notably improve the growth and cell migration ability of HCC827 cells, compared with gefitinib alone. When gefitinib and YC-1 were combined, the inhibiting effect on the growth and cell migration ability of HCC827 cells was substantially enhanced, compared with the control cells. Pearson's correlation analysis revealed that the p-Met expression level had a strong positive correlation with HIF-1α expression levels. Thus, it was concluded that the HIF-1 signaling pathway influences the sensitivity of HCC827 cells to gefitinib. The positive correlation between p-Met and HIF-1α expression levels may be the underlying mechanism of the HIF-1 signaling pathway influencing the sensitivity of HCC827 cells to gefitinib.

Metformin sensitizes hypoxia-induced gefitinib treatment resistance of HNSCC via cell cycle regulation and EMT reversal

Objectives

The objectives of this study were to explore the mechanisms of metformin sensitization to hypoxia-induced gefitinib treatment in resistant head and neck squamous cell carcinoma (HNSCC) and evaluate the effects of this combined treatment strategy.

Methods

The effects of gefitinib treatment on HNSCC were measured under normoxic and hypoxic conditions. The relationship between hypoxia and cell cycle and epithelial-mesenchymal transition (EMT) in tumor cells were analyzed. Palbociclib and LY294002 were used in combination with gefitinib to evaluate the effects on HNSCC cell cytotoxicity during hypoxia. Finally, metformin was used to evaluate the sensitizing effects of gefitinib treatment on HNSCC in vivo and in vitro.

Results

Cell viability and apoptosis assays demonstrated a significant difference in HNSCC cells treated with gefitinib between the normoxia and hypoxia groups. Hypoxia induced the expression of cyclin D1, decreased the percentage of cells in G1, and promoted the EMT of tumor cells. Both palbociclib and LY294002 enhanced gefitinib-induced cytotoxicity of HNSCC cells under hypoxic conditions. Encouragingly, metformin sensitized HNSCC to gefitinib treatment in vivo and in vitro.

Conclusion

Hypoxia promotes G1-S cell cycle progression and EMT in HNSCC, resulting in gefitinib treatment resistance. Metformin sensitizes HNSCC to gefitinib treatment, which might serve as a novel combined treatment strategy.

Thick-wall cavity predicts worse progression-free survival in lung adenocarcinoma treated with first-line EGFR-TKIs

BACKGROUND

Cavity occurs in 5.7 to 14.9% of patients with lung adenocarcinoma (ADC). However, the impact of cavity on the therapeutic response to epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) in ADC patients with EGFR mutations remains unclear. The aim of the present retrospective study was to elucidate the incidence and detailed characteristics of EGFR-mutant cavitary ADC and investigate the efficacy of EGFR-TKI treatment in this subgroup.

METHODS

Two hundred seventy-six consecutive patients with advanced EGFR-mutant lung ADC treated with first-line EGFR-TKIs were enrolled. Cavitation and the thickness of cavity wall were assessed based on high-resolution computed tomography scans. Progression-free survival (PFS) was analyzed by the Kaplan-Meier plots and the log-rank test was used to calculate the significance between groups.

RESULTS

Cavity occurred in 5.4% (15/276) of patients with EGFR-mutant lung ADC and was more prevalent among male patients (66.7% vs. 33.3%, P = 0.008). Of the 15 EGFR-mutant cavitary ADC, 9 patients had exon 19 deletion (19DEL) and 6 harbored L858R mutation, 9 patients had thick-wall cavity while 6 had thin-wall cavity. Cavity had an adverse impact on the PFS of EGFR-mutant ADC treated with first-line EGFR-TKIs (noncavity versus cavity, 11.0 versus 6.5 months, hazard ratio [HR]: 0.33, 95% confidence interval [CI], 0.15-0.73, P = 0.003). The impaired effect was only observed in patients with L858R mutation (11.0 vs. 4.2 months, HR: 0.05, 95%CI, 0.01-0.27, P = 0.0003) but not in those with 19DEL (10.4 versus 9.7 months, HR: 0.73, 95%CI, 0.30-1.75, P = 0.483). All six L858R-mutant cavitary ADC patients had thick-wall cavity while thick-wall cavity was only identified in one thirds (3/9) of patients with 19DEL. Further analyses showed that patients with thick-wall cavity had worse PFS (6.0 versus 11.0 months, P = 0.013). Multivariate analysis identified cavity as an independent predictive factor for PFS (HR: 0.49, 95% CI, 0.26-0.90, P = 0.022).

CONCLUSION

Cavitary ADC was associated with a worse PFS of first-line EGFR-TKI therapy, mainly in those with L858R mutation. Thick-wall cavity formation may be the main cause that contribute to the worse PFS.

18F-fluorodeoxyglucose positron emission tomography is correlated with the pathological necrosis and decreased microvessel density in lung adenocarcinomas

OBJECTIVE

We explored the relationship between preoperative ¹⁸F-FDG-PET parameters, tumor necrosis, and microvessel density (MVD) in patients with pulmonary adenocarcinomas.

METHODS

A total of 164 patients, who underwent surgical resection for lung adenocarcinoma, were reviewed retrospectively. The maximum standardized uptake value (SUV_max), peak SUV corrected for lean body mass (SUL_peak), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) values were measured by preoperative ¹⁸F-FDG-PET. The extent of tumor necrosis was examined and CD31 expression was evaluated to count the MVD.

RESULTS

The SUV_max, SUL_peak, MTV, and TLG levels were significantly lower in patients exhibiting no necrosis compared to those with necrosis. When we divided the patients into two groups based on high vs. low PET parameter values, elevated SUV_max, SUL_peak, MTV, and TLG values were significantly more associated with partial or diffuse necrosis than were lower values (p < 0.001). A negative correlation was evident between the MVD and SUV_max, MVD and SUL_peak, MVD and MTV, and MVD and TLG. Tumor necrosis was correlated with a shorter overall survival (OS) (p = 0.007) and recur-free survival (RFS) (p < 0.001). However, multivariate analysis revealed that necrosis was not of prognostic significance. The SUV_max, MTV and TLG were associated with inferior OS or RFS rates in univariate analysis, however, not in multivariate analysis.

CONCLUSION

High-level FDG accumulation is correlated with tumor necrosis in lung adenocarcinoma.

Severe hypoxia increases expression of ATM and DNA-PKcs and it increases their activities through Src and AMPK signaling pathways

BACKGROUND

Solid tumors often contain hypoxic regions because an abnormal and inefficient tumor vasculature is unable to supply sufficient oxygen. Tissue hypoxia is generally defined as a low oxygen concentration of less than 2%. It is well known that tumor cells under severe hypoxia, where oxygen concentration is less than 0.1%, show radioresistance. It has been reported that cells under severe hypoxia show different responses from those under mild hypoxia, where oxygen concentration is 0.5-2.0%. In the present study, we investigated the effects of severe hypoxia on expression and activities of ATM and DNA-dependent protein kinase catalytic subunit (DNA-PKcs), both of which regulate DNA double-strand breaks (DSBs) repair and radiation sensitivity. Signaling pathways for increasing expression and activities of ATM and DNA-PKcs under severe hypoxia were also investigated.

METHODS

SV40-transformed human fibroblast cell lines, LM217 and LM205, and normal human dermal fibroblasts (NHDF) were used. Cells were cultured at an oxygen concentration of less than 0.05% for 12 or 24 h. Activities and/or expression of ATM, DNA-PKcs, Src, Caveolin-1, EGFR, HIF-1α, PDK1, Akt, AMPKα, and mTOR were estimated by Western blot analyses.

RESULTS

Severe hypoxia increased expression and activities of ATM, DNA-PKcs, Src, Caveolin-1, EGFR, PDK1, Akt, and AMPKα, and decreased expression and activity of mTOR. A specific Src inhibitor, PP2 suppressed activation of ATM, DNA-PKcs, Caveolin-1, EGFR, and Akt under severe hypoxia. Treatment with siRNA for AMPKα suppressed activation of ATM and DNA-PKcs and increase of ATM expression under severe hypoxia.

CONCLUSION

Our data show that severe hypoxia increases activities of ATM and DNA-PKcs through Src and AMPK signaling pathways, and that activation of AMPK under hypoxia causes increase of ATM expression. Since ATM and DNA-PKcs play important roles in DSBs repair induced by ionizing radiation, those data provide novel insights on the molecular mechanism of the cellular radioresistance under severe hypoxia.

Dasatinib Suppresses TGFβ-Mediated Epithelial-Mesenchymal Transition in Alveolar Epithelial Cells and Inhibits Pulmonary Fibrosis

PURPOSE

Transforming growth factor β (TGFβ)-mediated epithelial-mesenchymal transition (EMT) of alveolar epithelial cells contributes to pulmonary fibrosis. Dasatinib (DAS), a potent and broad-spectrum tyrosine kinase inhibitor, has been widely studied as an anti-cancer agent. However, the therapeutic application of DAS for pulmonary fibrosis has not been clarified. Our purpose here is to investigate the effect of DAS on TGFβ1-induced EMT in human alveolar and bronchial epithelial cells in vitro and to evaluate the efficacy of DAS on lung fibrosis in vivo.

METHODS

TGFβ1-stimulated human alveolar epithelial (A549) and bronchial epithelial (BEAS-2B) cells were treated with or without DAS in vitro. Murine pulmonary fibrosis model was generated by injection of bleomycin (BLM).

RESULTS

A549 and BEAS-2B cells exposed to TGFβ1 underwent EMT, as indicated by downregulation of epithelial protein E-cadherin and induction of the mesenchymal proteins, fibronectin and type I and type IV collagen. These effects were dramatically suppressed by DAS treatment, which also prevented Smad2 and Smad3 phosphorylation. DAS inhibited TGFβ1-induced cell motility and migration. Furthermore, DAS administration significantly attenuated lung fibrosis in mice by histological analysis. Treatment with DAS also significantly reduced the levels of collagen and fibronectin and phosphorylation of Smad2 in the lung tissues of the murine model.

CONCLUSIONS

These findings suggest that DAS inhibited TGFβ-mediated EMT of alveolar and bronchial epithelial cells and attenuated BLM-induced lung fibrosis in mice by suppressing the TGFβ/Smad pathway. DAS may be a promising and novel anti-fibrotic agent for preventing lung fibrosis.

Propofol Reversed Hypoxia-Induced Docetaxel Resistance in Prostate Cancer Cells by Preventing Epithelial-Mesenchymal Transition by Inhibiting Hypoxia-Inducible Factor 1α

Prostate cancer is the second most frequently diagnosed cancer worldwide. Hypoxia-induced epithelial–mesenchymal transition (EMT), driven by hypoxia-inducible factor 1α (HIF-1α), is involved in cancer progression and metastasis. The present study was designed to explore the role of propofol in hypoxia-induced resistance of prostate cancer cells to docetaxel. We used the Cell Counting Kit-8 and 5-ethynyl-2′-deoxyuridine incorporation assay to measure cell viability and cell proliferation, respectively, in prostate cancer cell lines. Then, we detected HIF-1α, E-cadherin, and vimentin expression using western blotting. Propofol reversed the hypoxia-induced docetaxel resistance in the prostate cancer cell lines. Propofol not only decreased hypoxia-induced HIF-1α expression, but also reversed hypoxia-induced EMT by suppressing HIF-1α. Furthermore, small interfering RNA–mediated silencing of HIF-1α reversed the hypoxia-induced docetaxel resistance, although there was little change in docetaxel sensitivity between the hypoxia group and propofol group. The induction of hypoxia did not affect E-cadherin and vimentin expression, and under the siRNA knockdown conditions, the effects of propofol were obviated. These data support a role for propofol in regulating EMT in prostate cancer cells. Taken together, our findings demonstrate that propofol plays an important role in hypoxia-induced docetaxel sensitivity and EMT in prostate cancer cells and that it is a potential drug for overcoming drug resistance in prostate cancer cells via HIF-1α suppression.

Functional Genomics Approach Identifies Novel Signaling Regulators of TGFα Ectodomain Shedding

Ectodomain shedding of cell-surface precursor proteins by metalloproteases generates important cellular signaling molecules. Of importance for disease is the release of ligands that activate the EGFR, such as TGFα, which is mostly carried out by ADAM17 [a member of the A-disintegrin and metalloprotease (ADAM) domain family]. EGFR ligand shedding has been linked to many diseases, in particular cancer development, growth and metastasis, as well as resistance to cancer therapeutics. Excessive EGFR ligand release can outcompete therapeutic EGFR inhibition or the inhibition of other growth factor pathways by providing bypass signaling via EGFR activation. Drugging metalloproteases directly have failed clinically because it indiscriminately affected shedding of numerous substrates. It is therefore essential to identify regulators for EGFR ligand cleavage. Here, integration of a functional shRNA genomic screen, computational network analysis, and dedicated validation tests succeeded in identifying several key signaling pathways as novel regulators of TGFα shedding in cancer cells. Most notably, a cluster of genes with NFκB pathway regulatory functions was found to strongly influence TGFα release, albeit independent of their NFκB regulatory functions. Inflammatory regulators thus also govern cancer cell growth-promoting ectodomain cleavage, lending mechanistic understanding to the well-known connection between inflammation and cancer.Implications: Using genomic screens and network analysis, this study defines targets that regulate ectodomain shedding and suggests new treatment opportunities for EGFR-driven cancers. Mol Cancer Res; 16(1); 147-61. ©2017 AACR.

Targeting Hypoxia to Improve Non-Small Cell Lung Cancer Outcome

Oxygen deprivation (hypoxia) in non-small cell lung cancer (NSCLC) is an important factor in treatment resistance and poor survival. Hypoxia is an attractive therapeutic target, particularly in the context of radiotherapy, which is delivered to more than half of NSCLC patients. However, NSCLC hypoxia-targeted therapy trials have not yet translated into patient benefit. Recently, early termination of promising evofosfamide and tarloxotinib bromide studies due to futility highlighted the need for a paradigm shift in our approach to avoid disappointments in future trials. Radiotherapy dose painting strategies based on hypoxia imaging require careful refinement prior to clinical investigation. This review will summarize the role of hypoxia, highlight the potential of hypoxia as a therapeutic target, and outline past and ongoing hypoxia-targeted therapy trials in NSCLC. Evidence supporting radiotherapy dose painting based on hypoxia imaging will be critically appraised. Carefully selected hypoxia biomarkers suitable for integration within future NSCLC hypoxia-targeted therapy trials will be examined. Research gaps will be identified to guide future investigation. Although this review will focus on NSCLC hypoxia, more general discussions (eg, obstacles of hypoxia biomarker research and developing a framework for future hypoxia trials) are applicable to other tumor sites.

Understanding and targeting resistance mechanisms in NSCLC

The expanding spectrum of both established and candidate oncogenic driver mutations identified in non-small-cell lung cancer (NSCLC), coupled with the increasing number of clinically available signal transduction pathway inhibitors targeting these driver mutations, offers a tremendous opportunity to enhance patient outcomes. Despite these molecular advances, advanced-stage NSCLC remains largely incurable due to therapeutic resistance. In this Review, we discuss alterations in the targeted oncogene ('on-target' resistance) and in other downstream and parallel pathways ('off-target' resistance) leading to resistance to targeted therapies in NSCLC, and we provide an overview of the current understanding of the bidirectional interactions with the tumour microenvironment that promote therapeutic resistance. We highlight common mechanistic themes underpinning resistance to targeted therapies that are shared by NSCLC subtypes, including those with oncogenic alterations in epidermal growth factor receptor (EGFR), anaplastic lymphoma kinase (ALK), ROS1 proto-oncogene receptor tyrosine kinase (ROS1), serine/threonine-protein kinase b-raf (BRAF) and other less established oncoproteins. Finally, we discuss how understanding these themes can inform therapeutic strategies, including combination therapy approaches, and overcome the challenge of tumour heterogeneity.

Co-delivery of oxygen and erlotinib by aptamer-modified liposomal complexes to reverse hypoxia-induced drug resistance in lung cancer

Tumor hypoxia is a common feature of the tumor microenvironment and has been regarded as one of the key factors in driving the emergence of drug resistance in solid tumors. To surmount the hypoxia-associated drug resistance, we fabricated the novel multifunctional liposomal complexes (ACLEP) that could co-deliver oxygen and molecular targeted drug to overcome the hypoxia-induced drug resistance in lung cancer. The ACLEP were fabricated with liposomes anchored with anti-EGFR aptamer-conjugated chitosan to co-administrate erlotinib and PFOB to EGFR-overexpressing non-small-cell lung cancer. Our results showed that the ACLEP possessed desired physicochemistry, good biostability and controlled drug release. The entrapped PFOB in nanoparticle facilitated the uptake of ACLEP in either normoxia or hypoxic condition. Comparing to those nanoparticles loading erlotinib alone, our innovative oxygen/therapeutic co-delivery system showed a promising outcome in fighting against hypoxia-evoked erotinib resistance both in vitro and in vivo. Hence, this work presents a potent drug delivery platform to overcome hypoxia-induced chemotherapy resistance.

Differential expression of circulating biomarkers of tumor phenotype and outcomes in previously treated non-small cell lung cancer patients receiving erlotinib vs. cytotoxic chemotherapy

Background

The objective of this study was to identify serum biomarkers capable of predicting clinical outcomes in previously-treated NSCLC patients with wild-type for EGFR activating mutations or insufficient tissue for mutation status determination.

Methods

Sixty-six Luminex immunoassays representative of biological themes that emerged from a re-analysis of transcriptome data from the Cancer Genome Atlas (TCGA) were evaluate against pretreatment serum specimens from previously-treated advanced NSCLC patients received either cytotoxic chemotherapy (n=32) or erlotinib (n=79). Known EGFR mutation positive cases were excluded from analysis. Associations of biomarkers with outcome parameters and their differential interaction with treatment for survival outcomes were assessed using multivariate Cox PH analyses.

Results

Our EMT-based transcriptomic analysis revealed a range of biological processes associated with angiogenesis, apoptosis, cachexia, inflammation, and metabolism emerging as those most highly associated with patient outcome. These processes were evaluated via surrogate serum biomarkers. A treatment-biomarker interaction analysis revealed that higher pretreatment levels of c-Met signaling biomarkers (i.e. HGF levels), pro-inflammatory/ pro-cachexia (e.g. IL-8, sIL-2Rα, FGF-2) processes and a pro-angiogenic (e.g. TGF-α, IL-8, VEGF) milieu were associated with inferior survival (HR=0.35, 0.29, 0.58, 0.50, 0.61, 0.45, respectively; all p<0.05) for patients receiving chemotherapy, relative to erlotinib. In contrast, high levels of decoy receptor for IL-1, sIL-1RII, and a high tissue vimentin/E-cadherin ratio were associated with a poor OS (HR=3.78; p=0.00055) in the erlotinib cohort.

Conclusions

Contemporary precision medicine initiatives that pair patient tumor characteristics with the optimal therapy type may maximize the use of agents targeting EGFR in the treatment of NSCLC.

Primary Double-Strike Therapy for Cancers to Overcome EGFR Kinase Inhibitor Resistance: Proposal from the Bench

Diverse molecular mechanisms that confer acquired resistance to EGFR tyrosine kinase inhibitors (TKIs) in lung cancers with sensitive EGFR mutations have been reported. However, it is not realistic to analyze for all these mechanisms at the time of resistance in clinical practice and establish adequate treatment targeting these numerous resistance mechanisms. Therefore, we believe that we should move our research focus from the exploration of "established" diverse resistance mechanisms to the elucidation of molecular mechanisms that enable cancer cells to remain alive at the early phase of the treatment. Here in this review, we summarize up-to-date molecular mechanisms that maintain residual tumor cells against EGFR TKI monotherapy in lung cancers with EGFR mutations. We classified these mechanisms into three categories. The first is a preexisting minor subpopulation with a resistance mechanism such as a pretreatment T790M mutation that can be detected by highly sensitivity methods. The second is the reversible drug-tolerant state that is often observed in cell line models and accounts for the lack of complete response and continued survival of cells exposed to EGFR TKIs in patients. And the last is the role of the microenvironment, including survival signaling from fibroblasts or dying cancer cells and the role of poor vascularization. Primary double-strike cancer therapy, or even initial multiple-strike therapy, to cancer cells that cotarget EGFR and survival mechanism(s) simultaneously would be a promising strategy to improve the outcomes of patients with EGFR mutations.

Clinicopathological and prognostic significance of hypoxia-inducible factor-1 alpha in lung cancer: a systematic review with meta-analysis

Hypoxia-inducible factor-1 alpha (HIF-1α) plays a vital role in the initiation, evaluation and prognosis in lung cancer. The prognostic value of HIF-1α reported in diverse study remains disputable. Accordingly, a meta-analysis was implemented to further understand the prognostic role of HIF-1α in lung cancer. The relationship between HIF-1α and the clinicopathological characteristics and prognosis of lung cancer were investigated by a meta-analysis. PubMed and Embase were searched from their inception to January 2015 for observational studies. Fixed-effects or random-effects meta-analyses were used to calculate odds ratios and 95% confidence intervals of different comparisons. A total of 20 studies met the criteria. The results showed that HIF-1α expression in lung cancer tissues was significantly higher than that in normal lung tissues. Expression of HIF-1α in patients with squamous cell carcinoma was significantly higher than that of patients with adenocarcinomas. Similarly, non-small cell lung cancer (NSCLC) patients had higher HIF-1α expression than small cell lung cancer (SCLC) patients. Moreover, lymph node metastasized tissues had higher HIF-1α expression than non-lymph node metastasized tissues. A high level HIF-1α expression was well correlated with the expression of vascular endothelial growth factor and epidermal growth factor receptor in the NSCLC. Notably, NSCLC or SCLC patients with positive HIF-1α expression in tumor tissues had lower overall survival rate than patients with negative HIF-1α expression. It was suggested that HIF-1α expression may be a prognostic biomarker and a potential therapeutic target for lung cancer.

Oct4 plays a crucial role in the maintenance of gefitinib-resistant lung cancer stem cells

Several recent studies have suggested that cancer stem cells (CSCs) are involved in resistance to gefitinib in non-small cell lung cancer (NSCLC). Oct4, a member of the POU-domain transcription factor family, has been shown to be involved in CSC properties of various cancers. We previously reported that Oct4 and the putative lung CSC marker CD133 were highly expressed in gefitinib-resistant persisters (GRPs) in NSCLC cells, and GRPs exhibited characteristic features of the CSCs phenotype. The aim of this study was to elucidate the role of Oct4 in the resistance to gefitinib in NSCLC cells with an activating epidermal growth factor receptor (EGFR) mutation. NSCLC cell lines, PC9, which express the EGFR exon 19 deletion mutation, were transplanted into NOG mice, and were treated with gefitinib in vivo. After 14-17 days of gefitinib treatment, the tumors still remained; these tumors were referred to as gefitinib-resistant tumors (GRTs). PC9-GRTs showed higher expression of Oct4 and CD133. To investigate the role of Oct4 in the maintenance of gefitinib-resistant lung CSCs, we introduced the Oct4 gene into PC9 and HCC827 cells carrying an activating EGFR mutation by lentiviral infection. Transfection of Oct4 significantly increased CD133-positive GRPs and the number of sphere formation, reflecting the self-renewal activity, of PC9 and HCC827 cells under the high concentration of gefitinib in vitro. Furthermore, Oct4-overexpressing PC9 cells (PC9-Oct4) significantly formed tumors at 1 × 10 cells/injection in NOG mice as compared to control cells. In addition, PC9-Oct4 tumors were more resistant to gefitinib treatment as compared to control cells in vivo. Finally, immunohistochemical analysis revealed that Oct4 was highly expressed in tumor specimens of EGFR-mutant NSCLC patients with acquired resistance to gefitinib. Collectively, these findings suggest that Oct4 plays a pivotal role in the maintenance of lung CSCs resistant to gefitinib in EGFR mutation-positive NSCLC.

The Microenvironment of Lung Cancer and Therapeutic Implications

The tumor microenvironment (TME) represents a milieu that enables tumor cells to acquire the hallmarks of cancer. The TME is heterogeneous in composition and consists of cellular components, growth factors, proteases, and extracellular matrix. Concerted interactions between genetically altered tumor cells and genetically stable intratumoral stromal cells result in an "activated/reprogramed" stroma that promotes carcinogenesis by contributing to inflammation, immune suppression, therapeutic resistance, and generating premetastatic niches that support the initiation and establishment of distant metastasis. The lungs present a unique milieu in which tumors progress in collusion with the TME, as evidenced by regions of aberrant angiogenesis, acidosis and hypoxia. Inflammation plays an important role in the pathogenesis of lung cancer, and pulmonary disorders in lung cancer patients such as chronic obstructive pulmonary disease (COPD) and emphysema, constitute comorbid conditions and are independent risk factors for lung cancer. The TME also contributes to immune suppression, induces epithelial-to-mesenchymal transition (EMT) and diminishes efficacy of chemotherapies. Thus, the TME has begun to emerge as the "Achilles heel" of the disease, and constitutes an attractive target for anti-cancer therapy. Drugs targeting the components of the TME are making their way into clinical trials. Here, we will focus on recent advances and emerging concepts regarding the intriguing role of the TME in lung cancer progression, and discuss future directions in the context of novel diagnostic and therapeutic opportunities.

The hypoxic tumor microenvironment: driving the tumorigenesis of non-small-cell lung cancer

Since the application of molecular biology in cancer biology, lung cancer research has classically focused on molecular drivers of disease. One such pathway, the hypoxic response pathway, is activated by reduced local oxygen concentrations at the tumor site. Hypoxia-driven gene and protein changes enhance epithelial-to-mesenchymal transition, remodel the extracellular matrix, drive drug resistance, support cancer stem cells and aid evasion from immune cells. However, it is not the tumor cells alone which drive this response to hypoxia, but rather their interaction with a complex milieu of supporting cells. This review will focus on recent advances in our understanding of how these cells contribute to the tumor response to hypoxia in non-small-cell lung cancer.

Intrinsic bevacizumab resistance is associated with prolonged activation of autocrine VEGF signaling and hypoxia tolerance in colorectal cancer cells and can be overcome by nintedanib, a small molecule angiokinase inhibitor

Colorectal cancer (CRC) is a common tumor type with a high mortality rate, in part due to intrinsic drug resistance. Although bevacizumab, a VEGF-directed neutralizing antibody, is particularly active in this pathology, some patients never respond for reasons not well understood. We here wish to clarify the role of autocrine VEGF signaling in the response of CRC cells to angiogenesis inhibition. Our results show that CRC cells with intrinsic bevacizumab-resistance displayed pronounced upregulation of autocrine HIF-VEGF-VEGFR signaling in response to prolonged bevacizumab exposure whereas the same signaling pathway was downregulated in bevacizumab-sensitive xenografts. Importantly, both bevacizumab-sensitive and -resistant CRC xenografts were sensitive to nintedanib, a small molecule angiokinase inhibitor, which was associated with inhibition of mTORC1. In vitro studies revealed that bevacizumab-resistant cells displayed intrinsically higher HIF-VEGF signaling intensity and hypoxia tolerance compared to their bevacizumab-sensitive counterparts. Interestingly, although nintedanib showed comparable activity toward bevacizumab-sensitive cells under normoxia and hypoxia, the drug was three-fold more toxic to the resistant cells under hypoxia, suggesting that nintedanib attenuated the survival signaling that usually protects these cells from hypoxia-mediated cell death. In conclusion, our findings support a role for autocrine VEGF signaling in the survival of CRC cells to hypoxia and thus to angiogenesis inhibition. We further show that nintedanib, a small molecule angiokinase inhibitor, is active toward CRC models with intrinsic bevacizumab resistance supporting clinical trials of nintedanib in patients that do not respond to bevacizumab, alone or in combination with bevacizumab to increase angiogenesis inhibition.

[Advances in hypoxia microenvironment and chemotherapy-resistant of lung cancer]

肺癌是我国近年来发病率最高的恶性肿瘤之一，肿瘤低氧首先在肺癌中被发现，低氧与肿瘤细胞的耐药、凋亡、迁徙、血管生成等有密切联系。化疗耐药是肺癌治疗失败、病情进展的重要原因之一，近年来相关研究较多，现对肺癌低氧微环境以及其诱导化疗耐药作用机制的研究进展进行综述。

Hypoxia modulates the activity of a series of clinically approved tyrosine kinase inhibitors

BACKGROUND AND PURPOSE

Hypoxia in tumours is known to cause resistance to conventional chemotherapeutic drugs. In contrast, little is known about the effects of hypoxia on targeted anti-cancer drugs. This study evaluated the effect of hypoxia on a series of clinically approved tyrosine kinase inhibitors (TKIs).

EXPERIMENTAL APPROACH

The effect of hypoxia (0.1% oxygen) on the activity of conventional cytotoxic drugs (5-fluorouracil, doxorubicin and vinblastine), the hypoxia-activated prodrug tirapazamine and 9 TKIs was determined in a panel of cell lines. Where hypoxia had a marked effect on chemosensitivity, Western blot analysis was conducted to determine the effect of hypoxia on target expression and the effect of TKIs on cell signalling response under aerobic and hypoxic conditions.

KEY RESULTS

Three patterns of chemosensitivity were observed: resistance under hypoxia, equitoxic activity against hypoxic and aerobic cells, and preferential cytotoxicity to hypoxic cells. Significant hypoxia selectivity (independent of HIF1) was observed in the case of dasatinib and this correlated with the ability of dasatinib to inhibit phosphorylation of Src at tyrosine 530. Sorafenib was significantly less effective under hypoxic conditions but resistance did not correlate with hypoxia-induced changes in Raf/MEK/ERK signalling.

CONCLUSIONS AND IMPLICATIONS

Hypoxia influences the activity of TKIs but in contrast to conventional cytotoxic drugs, preferential activity against hypoxic cells can occur. The search for hypoxia-targeted therapies has been long and fruitless and this study suggests that some clinically approved TKIs could preferentially target the hypoxic fraction of some tumour types.

Hypoxia induces resistance to ALK inhibitors in the H3122 non-small cell lung cancer cell line with an ALK rearrangement via epithelial-mesenchymal transition

Patients with non-small cell lung cancer (NSCLC) with echinoderm microtubule-associated protein-like 4 (EML4)-anaplastic lymphoma kinase (ALK) rearrangements generally respond to ALK inhibitors such as crizotinib. However, some patients with EML4-ALK rearrangements respond poorly to crizotinib. Hypoxia is involved in the resistance to chemotherapeutic treatments in several cancers, and we investigated the association between the responses to ALK inhibitors and hypoxia. Sensitivity of the H3122 NSCLC cell line (EML4-ALK rearrangement) to ALK inhibitors (crizotinib or alectinib) was investigated during a normoxic or hypoxic state using an MTT assay. We found that the cell line was resistant to the inhibitors during hypoxia. Hypoxia mediated morphologic changes, including cell scattering and the elongation of the cell shape, that are characteristic of the epithelial-mesenchymal transition (EMT). A migration assay demonstrated that the number of migrating cells increased significantly during hypoxia, compared with during normoxia. Regarding EMT-related molecules, the expressions of slug, vimentin, and fibronectin were increased while that of E-cadherin was decreased by hypoxia. In addition, hypoxia inducible factor 1A-knockdown cancelled the hypoxia-induced EMT and resistance. Our findings indicate that hypoxia induces resistance to ALK inhibitors in NSCLC with an EML4-ALK rearrangement via the EMT.

Prospective neoadjuvant analysis of PET imaging and mechanisms of resistance to Trastuzumab shows role of HIF1 and autophagy

Background:

Although Trastuzumab has improved survival of HER2+ breast cancer patients, resistance to the agent pre-exists or develops through the course of therapy. Here we show that a specific metabolism and autophagy-related cancer cell phenotype relates to resistance of HER2+ breast cancer to Trastuzumab and chemotherapy.

Methods:

Twenty-eight patients with locally advanced primary breast cancer were prospectively scheduled to received one cycle of Trastuzumab followed by a new biopsy on day 21, followed by taxol/Trastuzumab chemotherapy for four cycles before surgery. FDG PET/CT scan was used to monitor tumour response. Tissue samples were immunohistochemically analysed for metabolism and autophagy markers.

Results:

In pre-Trastuzumab biopsies, the LC3A+/HER2+ cell population was correlated with HIF1α expression (P=0.01), while GLUT1 and LC3B expression were correlated with Ki67 proliferation index (P=0.01 and P=0.01, respectively). FDG PET tumour dimensions before therapy were correlated with LC3B expression (P=0.005). Administration of Trastuzumab significantly reduced clinical and PET-detected tumour dimensions (P<0.01). An inverse association of tumour response with the percentage of cells expressing HIF1α at baseline was documented (P=0.01). Administration of Trastuzumab resulted in a decrease of the proliferation index (P=0.004), GLUT1 (P=0.04) and HER2 (P=0.01) expression. In contrast, the percentage of LC3A+/HER2+ cells was increased (P=0.01). High baseline HIF1α expression was the only parameter associated with poorer pathological response to preoperative chemotherapy (P=0.001).

Conclusions:

As the HER2+/LC3A+ phenotype, which often overexpresses HIF1α, is a major subpopulation increasing after therapy with Trastuzumab, LC3A- and HIF1α-targeting therapies should be investigated for the augmentation of anti-HER2 therapy efficacy.