Characterising acquired resistance to erlotinib in non-small cell lung cancer patients

GRHL2-HER3 and E-cadherin mediate EGFR-bypass drug resistance in lung cancer cells

Epidermal growth factor receptor (EGFR) is a major oncogenic protein, and thus EGFR-targeting therapies are widely used in patients with various types of cancer, including lung cancer. However, resistance to EGFR inhibitors, such as erlotinib, presents a significant challenge in treating lung cancer. In this study, we established an EGFR-independent, erlotinib-resistant (ER) phenotype in lung cancer A549 cells by exposing them to erlotinib for an extended period. The resulting ER cells exhibited a dramatic increase in erlotinib resistance, a decreased EGFR protein level, and enhanced tumor growth, suggesting a robust mechanism bypassing EGFR inhibition. RNA sequencing identified the transcription factor GRHL2 as a critical player in this resistance. GRHL2 was upregulated in ER cells, and its knockdown and knockout significantly reduced erlotinib resistance. Further analysis revealed that GRHL2 upregulates the receptor tyrosine kinase HER3, and that HER3 knockdown similarly decreases the IC50 for erlotinib. Additionally, ER cells showed increased cell-cell adhesion, linked to upregulated E-cadherin. E-cadherin was found to be vital for erlotinib resistance, largely independent of GRHL2, highlighting multiple parallel pathways sustaining resistance. These findings provide a novel mechanism of drug resistance and suggest that combination therapies targeting both GRHL2-HER3 and E-cadherin-mediated pathways may be necessary to overcome erlotinib resistance in lung cancer.

Inhibiting FGFR by toadflax reverses erlotinib resistance in nonsmall cell lung cancer

This study aims to demonstrate the effect of toadflax (bufalin) on erlotinib resistance in nonsmall cell lung cancer (NSCLC) by inhibiting the fibroblast growth factor receptor (FGFR). The microfluidic mobility transferase and caliper mobility-shift assays were employed to detect the FGFR inhibition by bufalin and the binding reversibility. Further, the inhibitory effects of bufalin were determined in HCC827 and HCC827/ER cells in vitro, investigating relative FGFR overexpression by quantitative reverse transcriptase-PCR (RT-qPCR) and FGFR downstream proteins, that is, FGFR substrate 2 (FRS2), extracellular signal-regulated kinase (ERK), and S6 by western blot analysis. Finally, HCC827/ER-inoculated xenograft tumors were constructed to observe the effects of bufalin and bufalin + erlotinib intervention on tumor growth. Bufalin inhibited FGFR by reversibly binding to FGFR1. In addition, the western blot analysis indicated a significant reduction in the expression levels of FGFR, FRS2, ERK, and S6 proteins in HCC827 and HCC827/ER cells, increasing the expression levels of apoptotic caspase-3 and poly-(ADP-ribose) polymerase proteins. Bufalin + erlotinib combination significantly inhibited the apoptosis of HCC827/ER cells and subsequent tumor growth in vivo. In addition, FGFR overexpression significantly reversed the sensitivity of bufalin to HCC827/ER cells, promoting the value-addition of HCC827/ER cells. Further, bufalin + erlotinib significantly reduced the growth of erlotinib-resistant HCC827/ER tumors, induced apoptosis, and inhibited the expression of FGFR and p-ERK proteins. These findings indicated that bufalin could reverse the erlotinib resistance in NSCLC by inhibiting the FGFR expression.

Cancer-associated fibroblast-derived colony-stimulating factor 2 confers acquired osimertinib resistance in lung adenocarcinoma via promoting ribosome biosynthesis

Acquired resistance is a major obstacle to the therapeutic efficacy of osimertinib in lung adenocarcinoma (LUAD), but the underlying mechanisms are still not fully understood. Cancer-associated fibroblasts (CAFs) are the most abundant stromal cell type in LUAD tumor-microenvironment (TME) and have emerged as a key player in chemoresistance. However, the function of CAFs in osimertinib resistance is still unclear. Here, we showed that CAFs derived from osimertinib-resistant LUAD tissues (CAFOR) produced much more colony-stimulating factor 2 (CSF2) than those isolated from osimertinib-sensitive tissues. CAFOR-derived CSF2 activated the Janus kinase 2 (JAK2)/Signal transducer and activator of transcription 3 (STAT3) signaling pathway and upregulated lnc-CSRNP3 in LUAD cells. Lnc-CSRNP3 then promoted the expression of nearby gene CSRNP3 by recruiting chromodomain helicase DNA binding protein 9 (CHD9) and inhibited the phosphatase activity of the serine/threonine protein phosphatase 1 catalytic subunit α (PP1α), thereby induced osimertinib resistance by enhancing ribosome biogenesis. Collectively, our study reveals a critical role for CAFs in the development of osimertinib resistance and identifies the CSF2 pathway as an attractive target for monitoring osimertinib efficacy and overcoming osimertinib resistance in LUAD.

Advancements in NSCLC: From Pathophysiological Insights to Targeted Treatments

With the global incidence of non-small cell lung cancer (NSCLC) on the rise, the development of innovative treatment strategies is increasingly vital. This review underscores the pivotal role of precision medicine in transforming NSCLC management, particularly through the integration of genomic and epigenomic insights to enhance treatment outcomes for patients. We focus on the identification of key gene mutations and examine the evolution and impact of targeted therapies. These therapies have shown encouraging results in improving survival rates and quality of life. Despite numerous gene mutations being identified in association with NSCLC, targeted treatments are available for only a select few. This paper offers an exhaustive analysis of the pathogenesis of NSCLC and reviews the latest advancements in targeted therapeutic approaches. It emphasizes the ongoing necessity for research and development in this domain. In addition, we discuss the current challenges faced in the clinical application of these therapies and the potential directions for future research, including the identification of novel targets and the development of new treatment modalities.

Targeting KCa3.1 channels to overcome erlotinib resistance in non-small cell lung cancer cells

Almost all non-small cell lung cancer (NSCLC) patients initially responding to EGFR tyrosine kinase inhibitors (TKIs) develop acquired resistance. Since KCa3.1 channels, expressed in mitochondria and plasma membrane, regulate similar behavioral traits of NSCLC cells as EGFR, we hypothesized that their blockade contributes to overcoming EGFR-TKI resistance. Meta-analysis of microarray data revealed that KCa3.1 channel expression in erlotinib-resistant NSCLC cells correlates with that of genes of integrin and apoptosis pathways. Using erlotinib-sensitive and -resistant NSCLC cells we monitored the role of mitochondrial KCa3.1 channels in integrin signaling by studying cell-matrix adhesion with single-cell force spectroscopy. Apoptosis was quantified with fluorescence-based assays. The function of mitochondrial KCa3.1 channels in these processes was assessed by measuring the mitochondrial membrane potential and by quantifying ROS production. Functional assays were supplemented by biochemical analyses. We show that KCa3.1 channel inhibition with senicapoc in erlotinib-resistant NSCLC cells increases cell adhesion by increasing β1-integrin expression, that in turn depends on mitochondrial ROS release. Increased adhesion impairs migration of NSCLC cells in a 3D matrix. At the same time, the senicapoc-dependent ROS production induces cytochrome C release and triggers apoptosis of erlotinib-resistant NSCLC cells. Thus, KCa3.1 channel blockade overcomes EGFR-TKI resistance by inhibiting NSCLC motility and inducing apoptosis.

T-box transcription factor 19 promotes hepatocellular carcinoma metastasis through upregulating EGFR and RAC1

The effect of targeted therapy for metastatic hepatocellular carcinoma (HCC) is still unsatisfactory. Exploring the underlying mechanism of HCC metastasis is favorable to provide new therapeutic strategies. T-box (TBX) transcription factor family genes, which are crucial regulators in embryo and organ development, are vital for regulating tumor initiation, growth and metastasis. Here we explored the role of TBX19 in HCC metastasis, which is one of the most upregulated TBX family genes in human HCC tissues. TBX19 expression was markedly upregulated in HCC tissues and elevated TBX19 expression predicted poor prognosis. Overexpression of TBX19 enhanced HCC metastasis through upregulating epidermal growth factor receptor (EGFR) and Rac family small GTPase 1 (RAC1) expression. Downregulation of EGFR and RAC1 inhibited TBX19-mediated HCC metastasis, while upregulation of EGFR and RAC1 restored inhibition of HCC metastasis mediated by TBX19 knockdown. Furthermore, epidermal growth factor (EGF)/EGFR signaling upregulated TBX19 expression via the extracellular signal-regulated kinase (ERK)/nuclear factor (NF)-kB axis. Besides, the combined application of EGFR inhibitor Erlotinib and RAC1 inhibitor NSC23766 markedly inhibited TBX19-mediated HCC metastasis. In HCC cohorts, TBX19 expression was positively associated with EGFR and RAC1 expression. Patients with positive coexpression of TBX19/EGFR or TBX19/RAC1 displayed the poorest prognosis. In conclusion, EGF/EGFR signaling upregulated TBX19 expression via ERK/NF-kB pathway and TBX19 fostered HCC metastasis by enhancing EGFR and RAC1 expression, which formed an EGF-TBX19-EGFR positive feedback loop. Targeting this signaling pathway may offer a potential therapeutic strategy to efficiently restrain TBX19-mediated HCC metastasis.

Efficacy and Safety of First-Generation EGFR-TKIs Combined with Chemotherapy for Treatment-Naïve Advanced Non-Small-Cell Lung Cancer Patients Harboring Sensitive EGFR Mutations: A Single-Center, Open-Label, Single-Arm, Phase II Clinical Trial

PURPOSE

This single-center, open-label, single-arm, phase II clinical trial aimed to examine the efficacy and safety of the first-generation EGFR-TKIs combined with chemotherapy among treatment-naïve advanced non-small-cell lung cancer (NSCLC) patients harboring sensitive EGFR mutations.

MATERIALS AND METHODS

Patients with advanced EGFR-mutant NSCLC were given concurrent gefitinib (250 mg orally daily) and 3-week cycle of carboplatin plus pemetrexed for 4 to 6 cycles, followed by gefitinib maintenance until disease progression or unacceptable toxicity. The primary endpoint was progression-free survival (PFS), and the secondary endpoints were overall survival (OS), objective response rate (ORR), disease control rate (DCR) and safety. This trial was registered at ClinicalTrials.gov (NCT02886195).

RESULTS

Of the 21 patients enrolled in this study, a 76.2% ORR and 100% DCR were observed and a higher ORR was seen in patients with EGFR 21L858R mutations than in those with 19del mutations (P = 0.012). The subjects had a median PFS of 15.0 months and a median OS of 26.0 months, and numerically longer PFS was seen in patients with EGFR 21L858R mutations than in those with 19del mutations (P = 0.281). There were 15 NSCLC patients without cerebral metastases at baseline, with 4 cases developing cerebral metastases during the treatment, and the 6-, 12- and 24-month cumulative incidence rates of the central nervous system metastasis were 6.67%, 13.3% and 26.7%, respectively. There were 17 subjects with progressive diseases tested for EGFR T790M mutations, and 11 cases were positive for T790M mutations. Grade 3 toxicity included neutropenia (9.5%), leukopenia (4.8%), liver dysfunction (9.5%) and diarrhea (4.8%), and no grade 4 adverse events or treatment-related death occurred.

CONCLUSION

The combination of first-generation EGFR-TKIs and chemotherapy achieves a satisfactory PFS, ORR and DCR and well-tolerated toxicity in advanced NSCLC patients with EGFR mutations, notably in patients with EGFR L858R mutations.

Generation of Non-Small Cell Lung Cancer Patient-Derived Xenografts to Study Intratumor Heterogeneity

Simple Summary

It is widely thought that tumors are composed of different subpopulations of cancer cells carrying genetic alterations with some of them being common among all cells while others are unique for each subpopulation. This variable genetic profile of tumor cells is a component of what is collectively described as intratumor heterogeneity (ITH). Surviving the immune system and therapies, and establishing metastases are forces of natural selection that act upon ITH and drive tumor evolution and, eventually, the clinical presentation of patients. The aim of this prospective study was to investigate ITH in early-stage operable non-small cell lung cancer. We directly grafted human tumors in immunosuppressed mice and compared the genetic profile of the tumors grown in mice with that of the original human tumors. We identified clinical factors that affected the ability of human tumors to grow as mouse xenografts.

Abstract

Recent advances in sequencing technologies have allowed the in-depth molecular study of tumors, even at the single cell level. Sequencing efforts have uncovered a previously unappreciated heterogeneity among tumor cells, which has been postulated to be the driving force of tumor evolution and to facilitate recurrence, metastasis, and drug resistance. In the current study, focused on early-stage operable non-small cell lung cancer, we used tumor growth in patient-derived xenograft (PDX) models in mice as a fast-forward tumor evolution process to investigate the molecular characteristics of tumor cells that grow in mice, as well as the parameters that affect the grafting efficiency. We found that squamous cell carcinomas grafted significantly more efficiently compared with adenocarcinomas. Advanced stage, patient age and primary tumor size were positively correlated with grafting. Additionally, we isolated and characterized circulating tumor cells (CTC) from patients’ peripheral blood and found that the presence of CTCs expressing epithelial-to-mesenchymal (EMT) markers correlated with the grafting potential. Interestingly, exome sequencing of the PDX tumor identified genetic alterations in DNA repair and genome integrity genes that were under-represented in the human primary counterpart. In conclusion, through the generation of a PDX biobank of NSCLC, we identified the clinical and molecular properties of tumors that affected growth in mice.

Nano-synergistic combination of Erlotinib and Quinacrine for non-small cell lung cancer (NSCLC) therapeutics - Evaluation in biologically relevant in-vitro models

Non-small cell lung cancer (NSCLC), pre-dominant subtype of lung cancer, is a global disorder affecting millions worldwide. One of the early treatments for NSCLC was use of a first-generation tyrosine kinase inhibitor, Erlotinib (Erlo). However, chronic exposure to Erlo led to development of acquired drug resistance (ADR) in NSCLC, limiting the clinical use of Erlo. A potential approach to overcome development of ADR is a multi-drug therapy. It has been previously reported that Erlo and Quinacrine (QA), an anti-malarial drug, can work synergistically to inhibit tumor progression in NSCLC. However, the combination failed at clinical stages, citing lack of efficacy. In this study, an effort has been made to improve the efficacy of Erlo-QA combination via development of nanoformulations, known to enhance therapeutic efficacy of potent chemotherapies. Synergy between Erlo and QA was measured via estimating the combination indices (CI). It was seen that established combination of nanoformulations (CI: 0.25) had better synergy than plain drug solutions (CI: 0.85) in combination. Following extensive in-vitro testing, data were simulated in biologically relevant 3D tumor models. Two tumor models were developed for extensive in-vitro testing, 3D-Spheroids grown in ultra-low attachment culture plates for efficacy evaluation and a 5D-spheroid model in 5D-sphericalplate with capability of growing 750 spheroids/well for protein expression analysis. Extensive studies on these models revealed that combination of Erlo and QA nanoformulations overall had a better effect in terms of synergy enhancement as compared to plain drug combination. Further, effect of combinatorial therapy on molecular markers was evaluated on 5D-Sphericalplate leading to similar effects on synergy enhancement. Results from present study suggests that combination of nanoformulations can improve the synergy between Erlo and QA while reducing the overall therapeutic dose.

Transmembrane Peptides as Inhibitors of Protein-Protein Interactions: An Efficient Strategy to Target Cancer Cells?

Cellular functions are regulated by extracellular signals such as hormones, neurotransmitters, matrix ligands, and other chemical or physical stimuli. Ligand binding on its transmembrane receptor induced cell signaling and the recruitment of several interacting partners to the plasma membrane. Nowadays, it is well-established that the transmembrane domain is not only an anchor of these receptors to the membrane, but it also plays a key role in receptor dimerization and activation. Indeed, interactions between transmembrane helices are associated with specific biological activity of the proteins as cell migration, proliferation, or differentiation. Overexpression or constitutive dimerization (due notably to mutations) of these transmembrane receptors are involved in several physiopathological contexts as cancers. The transmembrane domain of tyrosine kinase receptors as ErbB family proteins (implicated in several cancers as HER2 in breast cancer) or other receptors as Neuropilins has been described these last years as a target to inhibit their dimerization/activation using several strategies. In this review, we will focus on the strategy which consists in using peptides to disturb in a specific manner the interactions between transmembrane domains and the signaling pathways (induced by ligand binding) of these receptors involved in cancer. This approach can be extended to inhibit other transmembrane protein dimerization as neuraminidase-1 (the catalytic subunit of elastin receptor complex), Discoidin Domain Receptor 1 (a tyrosine kinase receptor activated by type I collagen) or G-protein coupled receptors (GPCRs) which are involved in cancer processes.