Implications of MicroRNAs in the Treatment of Gefitinib-Resistant Non-Small Cell Lung Cancer

Circ_0091537 promotes gefitinib chemoresistance in non-small cell lung cancer by mediating the miR-520h/YAP1 network

Chemoresistance is the leading cause of poor outcomes of non-small cell lung cancer (NSCLC). Circular RNA (circRNA) plays a vital role in NSCLC resistance progression. Our study aimed to uncover the role of circRNA PDZ domain containing 8 (circ_0091537) in NSCLC with gefitinib resistance. The expression of circ_0091537, microRNA-520h (miR-520h), and Yes-associated protein 1 (YAP1) mRNA were detected using quantitative real-time PCR. Cell viability and cell proliferation were assessed by MTT assay and colony formation assay. Colony formation ability was detected by colony formation assay. Cell cycle distribution and cell apoptosis were determined by flow cytometry assay. Cell migration and cell invasion were detected by transwell assay. The potential relationship between miR-520h and circ_0091537 or YAP1 was verified by dual-luciferase reporter assay. Tumor formation assay in nude mice was performed to test the role of circ_0091537 in vivo . Circ_0091537 and YAP1 were upregulated, while miR-520h was downregulated in gefitinib-resistant NSCLC cells. Circ_0091537 knockdown inhibited gefitinib resistance in NSCLC cells and then inhibited NSCLC cell growth, migration, and invasion. MiR-520h was a target of circ_0091537, and miR-520h inhibition reversed the effects of circ_0091537 knockdown. Moreover, YAP1 was a target of miR-520h, and circ_0091537 competitively combined with miR-520h to enrich YAP1 expression. MiR-520h restoration impaired gefitinib resistance and suppressed NSCLC cell proliferation, migration, and invasion by repressing YAP1. Circ_0091537 overexpression weakened gefitinib sensitivity in vivo to promote tumor growth. Circ_0091537 strengthens gefitinib chemoresistance to promote NSCLC progression by mediating the miR-520h/YAP1 network, suggesting that circ_0091537 may be a key indicator in resistance to treatment of NSCLC.

The crucial roles of long noncoding RNA SNHGs in lung cancer

Lung cancer is one of the most common malignant tumors with growing morbidity and mortality worldwide. Several treatments are used to manage lung cancer, including surgery, radiotherapy and chemotherapy, as well as molecular-targeted therapy. However, the current measures are still far from satisfactory. Therefore, the current research should focus on exploring the molecular mechanism and then finding an effective treatment. Interestingly, we and others have embarked on a line of investigations focused on the mechanism of lung cancer. Specifically, lncRNA small nucleolar RNA host gene has been shown to be associated with biological characteristics and therapeutic resistance of lung cancer. In addition, small nucleolar RNA host genes may be used as diagnostic biomarker in the future. Herein, we will provide a brief review demonstrating the importance of small nucleolar RNA host genes in lung cancer, especially non-small cell lung cancer. Although lncRNA has shown a crucial role in tumor-related research, a large number of studies are needed to validate its clinical application in the future.

MicroRNAs as the critical regulators of tyrosine kinase inhibitors resistance in lung tumor cells

Lung cancer is the second most common and the leading cause of cancer related deaths globally. Tyrosine Kinase Inhibitors (TKIs) are among the common therapeutic strategies in lung cancer patients, however the treatment process fails in a wide range of patients due to TKIs resistance. Given that the use of anti-cancer drugs can always have side effects on normal tissues, predicting the TKI responses can provide an efficient therapeutic strategy. Therefore, it is required to clarify the molecular mechanisms of TKIs resistance in lung cancer patients. MicroRNAs (miRNAs) are involved in regulation of various pathophysiological cellular processes. In the present review, we discussed the miRNAs that have been associated with TKIs responses in lung cancer. MiRNAs mainly exert their role on TKIs response through regulation of Tyrosine Kinase Receptors (TKRs) and down-stream signaling pathways. This review paves the way for introducing a panel of miRNAs for the prediction of TKIs responses in lung cancer patients.

Identification of microRNA Signature and Key Genes Between Adenoma and Adenocarcinomas Using Bioinformatics Analysis

Background

In worldwide, colorectal cancer (CRC) is very common and the mechanisms remain unclear. This study aims to identify between adenomas with epithelial dislocation (false invasion) and adenomas with early adenocarcinoma (true invasion).

Methods

GSE41655 and GSE57965 datasets were obtained in the Gene Expression Omnibus (GEO) database. microRNA expression profiles and clinicopathological data from the TCGA (The Cancer Genome Atlas) database were downloaded to further validate the results in GEO. GEO software and the GEO2R calculation method were used to analyze two gene profiles. The co-expression of differentially expressed microRNAs (DEMs) and genes (DEGs) were identified and searched in the FunRich databases for pathway and ontology analysis. Cytoscape was utilized to construct the mRNA-microRNA network. Validation of gene expression levels was conducted by online databases and qRT-PCR and IHC experiments.

Results

In total, 6 DEMs and 34 DEGs are selected after calculating. KEGG results indicated that genes are enriched in certain tumor associated pathways. Four out of 6 microRNAs had a significant relationship with the overall survival (P < 0.05) and showed a good performance in predicting the survival risk of patients with colorectal carcinoma. Furthermore, expression levels of hsa-miR-455 and hsa-miR-125a were then verified by qRT-PCR which all target BCL2L12. IHC results showed that the expression level of BCL2L12 was higher in adenocarcinoma than in adenoma. Based on the selected gene, the top 10 small molecules were screened out as potential drugs.

Conclusion

By using microarray and bioinformatics analyses, DEMs and DEGs were selected and a complete gene network was constructed. To our knowledge, BCL2L12 and related molecules including hsa-miR-455 and hsa-miR-125a were firstly identified as potential biomarkers in the progression from adenoma to adenocarcinoma.

Identification of the miRNA signature and key genes in colorectal cancer lymph node metastasis

BACKGROUND

Because its metastasis to the lymph nodes are closely related to poor prognosis, miRNAs and mRNAs can serve as biomarkers for the diagnosis, prognosis, and therapy of colorectal cancer (CRC). This study aimed to identify novel gene signatures in the lymph node metastasis of CRC.

METHODS

GSE56350, GSE70574, and GSE95109 datasets were downloaded from the Gene Expression Omnibus (GEO) database, while data from 569 colorectal cancer cases were also downloaded from The Cancer Genome Atlas (TCGA) database. Differentially expressed miRNAs (DE-miRNAs) were calculated using R programming language (Version 3.6.3), while gene ontology and enrichment analysis of target mRNAs were performed using FunRich ( http://www.funrich.org ). Furthermore, the mRNA-miRNA network was constructed using Cytoscape software (Version 3.8.0). Gene expression levels were verified using the GEO datasets. Similarly, quantitative real-time PCR (qPCR) was used to examine expression profiles from 20 paired non-metastatic and metastatic lymph node tissue samples obtained from patients with CRC.

RESULTS

In total, five DE-miRNAs were selected, and 34 mRNAs were identified after filtering the results. Moreover, two key miRNAs (hsa-miR-99a, hsa-miR-100) and one gene (heparan sulfate-glucosamine 3-sulfotransferase 2 [HS3ST2]) were identified. The GEO datasets analysis and qPCR results showed that the expression of key miRNA and genes were consistent with that obtained from the bioinformatic analysis. A novel miRNA-mRNA network capable of predicting the prognosis and confirmed experimentally, hsa-miR-99a-HS3ST2-hsa-miR-100, was found after expression analysis in metastasized lymph node tissue from CRC samples.

CONCLUSION

In summary, miRNAs and genes with potential as biomarkers were found and a novel miRNA-mRNA network was established for CRC lymph node metastasis by systematic bioinformatic analysis and experimental validation. This network may be used as a potential biomarker in the development of lymph node metastatic CRC.

HS3ST2 and Its Related Molecules as Potential Biomarkers for Predicting Lymph Node Metastasis in Patients with Colorectal Cancer

Background

Lymph node metastasis is a major cause of cancer-related death in patients with colorectal cancer (CRC), but current strategies are limited to predicting this clinical behavior. Our study aims to establish a lymph node metastasis prediction model based on miRNA and mRNA to improve the accuracy of prediction.

Methods

GSE56350, GSE70574, and GSE95109 were downloaded from the Gene Expression Omnibus (GEO) database and 569 colorectal cancer statistics were also downloaded from The Cancer Genome Atlas (TCGA) database. Differentially expressed miRNAs were calculated by using R software. Besides, gene ontology and enriched pathway analysis of target mRNAs were analyzed by using FunRich. Furthermore, the mRNA–miRNA network was constructed using Cytoscape software. Gene expression level was also detected by performing qRT-PCR (quantitative real-time PCR) in colorectal cancer and lymph node tissues.

Results

In total, 5 differentially expressed miRNAs were selected, and 34 mRNAs were identified after filtering. The research of KEGG indicated that mRNAs are enriched in many cancer pathways. Differentially expressed miRNAs were most enriched in the cytoplasm, nucleoside, transcription factor activity, and RNA binding. KEGG pathway analysis of these target genes was mainly enriched in 5 pathways including fatty acid elongation, MAPK signaling pathway, autophagy, signaling pathways regulating pluripotency of stem cells, and Th17 cell differentiation. The results of qRT-PCR indicated that hsa-miR-100 and hsa-miR-99a were differentially expressed in lymph node metastatic colorectal cancer tissues and lymph node non-metastasis tissues which all target HS3ST2. Besides, we also found they have a significant difference in colorectal cancer tissues compared with normal tissues.

Conclusion

By using microarray and bioinformatics analyses, differentially expressed miRNAs were identified and a complete gene network was constructed. To our knowledge, HS3ST2 and related molecules including hsa-miR-100 and hsa-miR-99a were firstly identified as potential biomarkers in the development of lymph node metastatic colorectal cancer.

Exosomal microRNA in Pancreatic Cancer Diagnosis, Prognosis, and Treatment: From Bench to Bedside

Simple Summary

Pancreatic cancer is the fourth leading cause of cancer death in the United States and over 90% of the patients suffer from pancreatic ductal adenocarcinoma (PDAC). PDAC is the most lethal gastrointestinal malignancies and only 10% of the people survive more than 5 years, therefore, novel diagnostic, prognostic, and therapeutic strategies are an immediate necessity. Studies have demonstrated microRNAs in bodily fluids that are bound with membranes (exosomes) can act as stable biomarkers both for disease development and metastasis. The diagnostic, prognostic, as well as therapeutic roles of exosomal microRNAs in pancreatic cancer have been discussed in this review.

Abstract

Pancreatic cancer is the fourth leading cause of cancer death among men and women in the United States, and pancreatic ductal adenocarcinoma (PDAC) accounts for more than 90% of pancreatic cancer cases. PDAC is one of the most lethal gastrointestinal malignancies with an overall five-year survival rate of ~10%. Developing effective therapeutic strategies against pancreatic cancer is a great challenge. Novel diagnostic, prognostic, and therapeutic strategies are an immediate necessity to increase the survival of pancreatic cancer patients. So far, studies have demonstrated microRNAs (miRNAs) as sensitive biomarkers because of their significant correlation with disease development and metastasis. The miRNAs have been shown to be more stable inside membrane-bound vesicles in the extracellular environment called exosomes. Varieties of miRNAs are released into the body fluids via exosomes depending on the normal physiological or pathological conditions of the body. In this review, we discuss the recent findings on the diagnostic, prognostic, and therapeutic roles of exosomal miRNAs in pancreatic cancer.

microRNAs as Novel Therapeutics in Cancer

Simple Summary

Over the last few years, we have witnessed incredible advancements in anti-tumor drug development. microRNAs, a class of small non-coding RNAs dysregulated in all cancers, have been recently elected as candidate therapeutics for treating a variety of diseases, including cancer. The scope of this review is to give some insight into the role of the most relevant microRNAs in cancer. We will focus on examining their biological role in tumor development while also providing a broad overview of microRNAs as therapeutics. There is a dedicated focus on the different methods available for microRNA delivery in addition to the efforts being made to increase the specificity of these delivery methods. Finally, we discuss the ongoing clinical trials that are using microRNAs for cancer treatment.

Abstract

In the last 20 years, the functional roles for miRNAs in gene regulation have been well established. MiRNAs act as regulators in virtually all biological pathways and thus have been implicated in numerous diseases, including cancer. They are particularly relevant in regulating the basic hallmarks of cancer, including apoptosis, proliferation, migration, and invasion. Despite the substantial progress made in identifying the molecular mechanisms driving the deregulation of miRNAs in cancer, the clinical translation of these important molecules to therapy remains in its infancy. The paucity of vehicles available for the safe and efficient delivery of miRNAs and ongoing concerns for toxicity remain major obstacles to clinical application. Novel formulations and the development of new vectors have significantly improved the stability of oligonucleotides, increasing the effectiveness of therapy. Furthermore, the use of specific moieties for delivery in target tissues or cells has increased the specificity of treatment. The use of new technologies has allowed small but important steps toward more specific therapeutic delivery in tumor tissues and cells. Although a long road remains, the path ahead holds great potential. Currently, a few miRNA drugs are under investigation in human clinical trials with promising results ahead.

Identification of lymph node metastasis-related microRNAs in breast cancer using bioinformatics analysis

BACKGROUND

Lymph node metastasis is a significant problem in breast cancer, and its underlying molecular mechanism is still unclear. The purpose of this study is to research the molecular mechanism and to explore the key RNAs and pathways that mediate lymph node metastasis in breast cancer.

METHODS

GSE100453 and GSE38167 were downloaded from the Gene Expression Omnibus (GEO) database and 569 breast cancer statistics were also downloaded from the TCGA database. Differentially expressed miRNAs were calculated by using R software and GEO2R. Gene ontology and Enriched pathway analysis of target mRNAs were analyzed by using the Database for Database of Annotation Visualization and Integrated Discovery (DAVID) and R software. The protein-protein interaction (PPI) network was performed according to Metascape, String, and Cytoscape software.

RESULTS

In total, 6 differentially expressed miRNAs were selected, and 499 mRNAs were identified after filtering. The research of the Kyoto Encyclopedia of Genes and Genomes (KEGG) demonstrated that mRNAs enriched in certain tumor pathways. Also, certain hub mRNAs were highlighted after constructed and analyzed the PPI network. A total of 3 out of 6 miRNAs had a significant relationship with the overall survival (P < .05) and showed a good ability of risk prediction model of over survival.

CONCLUSIONS

By utilizing bioinformatics analyses, differently expressed miRNAs were identified and constructed a complete gene network. Several potential mechanisms and therapeutic and prognostic targets of lymph node metastasis were also demonstrated in breast cancer.

Therapeutic advances of miRNAs: A preclinical and clinical update

miRNAs, a class of small endogenous RNAs, are one of the essential biopharmaceuticals which are in commercial spans as next-generation medicine in recent times. A snapshot of the current scenario regarding the miRNAs as biopharmaceuticals have been discussed. In this work, biopharmaceutical companies working with miRNAs and the current status of preclinical/clinical trials about miRNA therapeutics have been reviewed. Finally, recent updates on the absorption, distribution, metabolism, and excretion (ADME), as well as a delivery system of miRNAs, have been illustrated.

Recent updates on the resistance mechanisms to epidermal growth factor receptor tyrosine kinase inhibitors and resistance reversion strategies in lung cancer

Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) have led to a substantial improvement in the prognosis of lung cancer patients by explicitly targeting the activating mutations within the EGFR. Initially, patients harboring tumors with EGFR mutations show progression-free survival and improvement in the response rates toward all-generation EGFR-TKIs; however, these agents fail to deliver the intended results in the long-term due to drug resistance. Therefore, it is necessary to recognize specific cardinal mechanisms that regulate the resistance phenomenon. Understanding the intricate mechanisms underlying EGFR-TKIs resistance in lung cancer could provide cognizance for more advanced targeted therapeutics. The present review features insights into current updates on the discrete mechanisms, including secondary or tertiary mutations, parallel and downstream signaling pathways, acquiring an epithelial-to-mesenchymal transition (EMT) signature, microRNAs (miRNAs), and epigenetic alterations, which lead to intrinsic and acquired resistance against EGFR-TKIs in lung cancer. In addition, this paper also reviews current possible strategies to overcome this issue using combination treatment of recently developed MET inhibitors, allosteric inhibitors or immunotherapies, transformation of EMT, targeting miRNAs, and epigenetic alterations in intrinsic and acquired EGFR-TKIs resistant lung cancer. In conclusion, multiple factors are responsible for intrinsic and acquired resistance to EGFR-TKIs and understanding of the detailed molecular mechanisms, and recent advancements in pharmacological studies are needed to develop new strategies to overcome intrinsic and acquired EGFR-TKIs resistance in lung cancer.

The miR‑625‑3p/AXL axis induces non‑T790M acquired resistance to EGFR‑TKI via activation of the TGF‑β/Smad pathway and EMT in EGFR‑mutant non‑small cell lung cancer

Gefitinib is currently the preferred treatment for non-small cell lung cancer (NSCLC) patients with epidermal growth factor receptor (EGFR)-activating mutation. However, some patients gradually develop acquired resistance after receiving treatment. In addition to secondary T790M mutation, the remaining mechanisms contributing to non-T790M mutations need to be explored. In the present study, NSCLC-derived HCC827 and PC-9 cells and the corresponding gefitinib-resistant cell lines (HCC827GR and PC9GR) were utilized. Next-generation DNA sequencing was performed on the HCC827GR and PC9GR cells. Under AXL receptor tyrosine kinase (AXL) knockdown or miR-625-3p overexpressing conditions, a cell growth inhibition assay was performed to evaluate gefitinib sensitivity. Wound healing and Transwell assays were used to examine the migratory and invasive abilities of the cells. Moreover, we also carried out western blot analysis to detect the altered downstream signaling pathway. Our study revealed markedly decreased miR-625-3p expression in the HCC827GR cell line, while its overexpression partly reversed gefitinib resistance. Integrated analysis based on Targetscan website showed that AXL can be potentially targeted by miR-625-3p and we further verified the hypothesis via dual-luciferase reporter assays. Mechanistic analysis revealed that TGF-β1-induced EMT may contribute to the miR-625-3p/AXL axis-mediated gefitinib resistance. Our data demonstrated that miR-625-3p contributes to the acquired resistance of gefitinib, which may provide novel insight to combat resistance to EGFR-TKIs.

Non-coding RNAs in Lung Cancer Chemoresistance

Background:

Lung cancer is the leading cause of cancer-associated death worldwide with limited treatment options. The major available treatment options are surgery, radiotherapy, chemotherapy and combinations of these treatments. In chemotherapy, tyrosine kinase inhibitors and taxol are the first lines of chemotherapeutics used for the treatment of lung cancer. Often drug resistance in the clinical settings hinders the efficiency of the treatment and intrigues the tumor relapse. Drug-resistance is triggered either by intrinsic factors or due to the prolonged cycles of chemotherapy as an acquired-resistance. There is an emerging role of non-coding RNAs (ncRNAs), including notorious microRNAs (miRNAs), proposed to be actively involved in the regulations of various tumor-suppressor genes and oncogenes.

Result:

The altered gene expression by miRNA is largely mediated either by the degradation or by interfering with the translation of targeted mRNA. Unlike miRNA, other type of ncRNAs, such as long non-coding RNAs (lncRNAs), can target the transcriptional activator or the repressor, RNA polymerase, and even DNA-duplex to regulate the gene expressions. Many studies have confirmed the crucial role of ncRNAs in lung adenocarcinoma progression and importantly, in the acquisition of chemoresistance. Recently, ncRNAs have become early biomarkers and therapeutic targets for lung cancer.

Conclusion:

Targeting ncRNAs could be an effective approach for the development of novel therapeutics against lung cancer and to overcome the chemoresistance.

Combination therapy of gefitinib and miR-30a-5p may overcome acquired drug resistance through regulating the PI3K/AKT pathway in non-small cell lung cancer

BACKGROUND

Non-small cell lung cancer (NSCLC) patients with an epidermal growth factor receptor (EGFR) mutation often initially respond to EGFR tyrosine kinase inhibitor (EGFR-TKI) treatment but may acquire drug resistance due to multiple factors. MicroRNAs are a class of small noncoding and endogenous RNA molecules that may play a role in overcoming the resistance.

MATERIALS AND METHODS

In this study, we explored and validated, through in vitro experiments and in vivo models, the ability of a combination treatment of EGFR-TKI, namely gefitinib, and a microRNA mimic, miR-30a-5p, to overcome drug resistance through regulation of the insulin-like growth factor receptor-1 (IGF1R) and hepatocyte growth factor receptor signaling pathways, which all converge on phosphatidylinositol 3 kinase (PI3K), in NSCLC. First, we examined the hypothesized mechanisms of drug resistance in H1650, H1650-acquired gefitinib-resistance (H1650GR), H1975, and H460 cell lines. Next, we investigated a potential combination treatment approach to overcome acquired drug resistance in the H1650GR cell line and an H1650GR cell implanted mouse model.

RESULTS

Dual inhibitors of EGFR and IGF1R significantly lowered the expression levels of phosphorylated protein kinase B (p-AKT) and phosphorylated mitogen-activated protein kinase (p-ERK) compared with the control group in all cell lines. With the ability to repress PI3K expression, miR-30a-5p mimics induced cell apoptosis, and inhibited cell invasion and migration in the treated H1650GR cell line.

CONCLUSION

Gefitinib, combined with miR-30a-5p mimics, effectively suppressed the growth of H1650GR-induced tumor in xenografts. Hence, a combination therapy of gefitinib and miR-30a-5p may play a critical role in overcoming acquired resistance to EGFR-TKIs. The reviews of this paper are available via the supplemental material section.

Research progress on the relationship between lung cancer drug-resistance and microRNAs

Lung cancer, a malignant tumor with the highest death rate of cancer, seriously endangers human health. And its pathogenesis and mechanism of drug resistance has been partially clarified, especially for the signal pathway of epidermal growth factor receptor (EGFR). The targeting therapy of EGFR signaling pathway in non-small cell lung cancer (NSCLC) has achieved a certain effect, but the two mutation of EGFR and other mechanisms of lung cancer resistance still greatly reduce the therapeutic effect of chemotherapy on it. MicroRNA is an endogenous non coding RNA, which has a regulatory function after transcriptional level. Recent studies on the mechanism of lung cancer resistance have found that a variety of microRNAs are related to the mechanism of lung cancer drug-resistance. They can regulate lung cancer resistance by participating in signal pathways, drug resistance genes and cell apoptosis, thus affecting the sensitivity of cancer cells to drugs. Therefore, microRNAs can be used as a specific target for the treatment of lung cancer and plays a vital role in the early diagnosis, prognosis and treatment of lung cancer. This article reviews the mechanisms of lung cancer resistance and its relationship with microRNAs.

Reciprocal regulation of miR-206 and IL-6/STAT3 pathway mediates IL6-induced gefitinib resistance in EGFR-mutant lung cancer cells

Persistently activated IL‐6/STAT3 pathway promotes acquired resistance to targeted therapy with epidermal growth factor receptor‐tyrosine kinase inhibitors (EGFR‐TKIs) in non–small‐cell lung cancer (NSCLC) treatment. miR‐206 has been verified to be dysregulated and plays as a negative regulator in lung cancer. However, whether miR‐206 may overcome IL6‐induced gefitinib resistance in EGFR‐mutant lung cancer remains elusive. In this study, we investigated the role of miR‐206 in IL6‐induced gefitinib‐resistant EGFR‐mutated lung cancer cell lines. We showed that forced miR‐206 expression restored gefitinib sensitivity in IL6‐induced gefitinib‐resistant EGFR‐mutant lung cancer cells by inhibiting IL6/JAK1/STAT3 pathway. Specifically, mechanistic investigations revealed that miR‐206 blocked IL‐6/STAT3 signalling via directly targeting the 3'‐UTR of intracellular IL‐6 messenger RNA. Moreover, IL‐6 induced miR‐206 down‐regulation by reducing the cropping process of primary miR‐206 (pri‐miR‐206) into the Drosha/DGCR8 complex. Taken together, our findings reveal a direct role of miR‐206 in regulating IL‐6/STAT3 pathway and contrarily activated IL‐6/STAT3 signalling mediates the miR‐206 maturation process in gefitinib‐resistant EGFR‐mutant lung cancer cells.

Trans-3,5,4´-trimethoxystilbene reduced gefitinib resistance in NSCLCs via suppressing MAPK/Akt/Bcl-2 pathway by upregulation of miR-345 and miR-498

Despite initial dramatic efficacy of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (EGFR‐TKIs) in EGFR‐mutant lung cancer patients, subsequent emergence of acquired resistance is almost inevitable. Resveratrol and its derivatives have been found to exert some effects on EGFR‐TKI resistance in non‐small cell lung cancer (NSCLC), but the underlying mechanisms remain unclear. We screened several NSCLC cell lines with gefitinib resistance by MTT assay and analysed the miR‐345/miR‐498 expression levels. NSCLC cells were pre‐treated with a resveratrol derivative, trans‐3,5,4‐trimethoxystilbene (TMS) and subsequently challenged with gefitinib treatment. The changes in apoptosis and miR‐345/miR‐498 expression were analysed by flow cytometry and q‐PCR respectively. The functions of miR‐345/miR‐498 were verified by CCK‐8 assay, cell cycle analysis, dual‐luciferase reporter gene assay and immunoblotting analysis. Our results showed that the expression of miR‐345 and miR‐498 significantly decreased in gefitinib resistant NSCLC cells. TMS pre‐treatment significantly upregulated the expression of miR‐345 and miR‐498 increasing the sensitivity of NSCLC cells to gefitinib and inducing apoptosis. MiR‐345 and miR‐498 were verified to inhibit proliferation by cell cycle arrest and regulate the MAPK/c‐Fos and AKT/Bcl‐2 signalling pathways by directly targeting MAPK1 and PIK3R1 respectively. The combination of TMS and gefitinib promoted apoptosis also by miR‐345 and miR‐498 targeting the MAPK/c‐Fos and AKT/Bcl‐2 signalling pathways. Our study demonstrated that TMS reduced gefitinib resistance in NSCLCs via suppression of the MAPK/Akt/Bcl‐2 pathway by upregulation of miR‐345/498. These findings would lay the theoretical basis for the future study of TMS for the treatment of EGFR‐TKI resistance in NSCLCs.

A large scale proteome analysis of the gefitinib primary resistance overcome by KDAC inhibition in KRAS mutated adenocarcinoma cells overexpressing amphiregulin

KDAC inhibitors (KDACi) overcome gefitinib primary resistance in non-small cell lung cancer (NSCLC) including mutant-KRAS lung adenocarcinoma. To identify which proteins are involved in the restoration of this sensitivity and to provide new therapeutic targets for mutant-KRAS lung adenocarcinoma, we performed an iTRAQ quantitative proteomic analysis after subcellular fractionation of H358-NSCLC treated with gefitinib and KDACi (TSA/NAM) versus gefitinib alone. The 86 proteins found to have been significantly dysregulated between the two conditions, were mainly involved in cellular metabolism and cell transcription processes. As expected, the pathway related to histone modifications was affected by the KDACi. Pathways known for controlling tumor development and (chemo)-resistance (miRNA biogenesis/glutathione metabolism) were affected by the KDACi/gefitinib treatment. Moreover, 57 dysregulated proteins were upstream of apoptosis (such as eEF1A2 and STAT1) and hence provide potential therapeutic targets. The inhibition by siRNA of eEF1A2 expression resulted in a slight decrease in H358-NSCLC viability. In addition, eEF1A2 and STAT1 siRNA transfections suggested that both STAT1 and eEF1A2 prevent AKT phosphorylation known for enhancing gefitinib resistance in NSCLC. Therefore, altogether our data provide new insights into proteome regulations in the context of overcoming the NSCLC resistance to gefitinib through KDACi in H358 KRAS mutated and amphiregulin-overexpressing NSCLC cells.

MicroRNA-133a downregulated EGFR expression in human non-small cell lung cancer cells via AKT/ERK signaling

MicroRNAs (miRNAs) may serve important roles in the regulation of human non-small cell lung cancer (NSCLC) cell growth and apoptosis. To the best of our knowledge, the present study was the first to explore the role of miRNA-133a/epidermal growth factor receptor (EGFR) in regulating NSCLC cell growth and apoptosis via the AKT/extracellular signal-regulated kinase (ERK) signaling pathway. It was determined that miRNA-133a expression was lower in NSCLC tissue than in the adjacent mucosae. Additionally, EGFR expression in the NSCLC tissue was higher compared with in the adjacent mucosae. Furthermore, the upregulation of miRNA-133a in NSCLC cells suppressed cell growth and induced apoptosis. Upregulating miRNA-133a also increased caspase-3 protein expression, while suppressing that of EGFR, phosphorylated (p)-AKT and p-ERK in NSCLC cells. Therefore, the results of the current study demonstrated that miRNA-133a downregulates EGFR expression in NSCLC via the AKT/ERK signaling pathway. These findings provide insights into the function of miRNA-133a in NSCLC, as well as into the molecular mechanisms underlying the miRNA-133a-mediated downregulation of the EGFR/AKT/ERK signaling pathway in NSCLC.

The long non-coding RNA SNHG5 regulates gefitinib resistance in lung adenocarcinoma cells by targetting miR-377/CASP1 axis

Gefitinib resistance is one of the major obstacles for the treatment of lung adenocarcinoma (LAD). The present study aimed to investigate the effects of the long non-coding RNA (lncRNA), small nucleolar RNA host gene 5SNHG5 on gefitinib resistance in LAD and explore the underlying mechanisms. The quantitative real-time PCR (qRT-PCR) results showed that SNHG5 expression was significantly down-regulated in LAD patients with acquired gefitinib resistance and gefitinib resistant LAD cell lines. SNHG5 overexpression sensitized gefitinib resistant LAD cells to gefitinib treatment, while knockdown of SNHG5 rendered gefitinib sensitive LAD cells to gefitinib treatment. Bioinformatics analysis showed that SNHG5 exerted its function through interaction with miR-377, which was further confirmed by luciferase reporter assay in 293T cells. Overexpression of SNHG5 suppressed the expression of miR-377, while the knockdown of SNHG5 increased the miR-377 expression. MiR-377 expression was significantly up-regulated in LAD specimens with acquired gefitinib resistance and was negatively correlated with SNHG5 expression. In addition, CASP1 was predicted as a downstream target of miR-377 Overexpression of miR-377 suppressed the expression of CASP1 in PC9 cells and knockdown of miR-377 increased the CASP1 expression in PC9GR cells. In vitro functional assay showed that knockdown of CASP1 in SNHG5-overexpressed PC9GR cells abolished their gefitinib resistance. Overall, the present study demonstrated, for the first time, that the SNHG5/miR-377/CASP1 axis functions as an important role in LAD cells gefitinib resistance and potentially contributes to the improvement of LAD diagnosis and therapy.

Differential MicroRNA Expression between EGFR T790M and L858R Mutated Lung Cancer

Background

MicroRNAs (miRNAs) are short, non-coding RNAs that mediate post-transcriptional gene regulation. They are commonly deregulated in human malignancies, including non-small cell lung cancer (NSCLC). The aim of this study is to investigate miRNA expression in T790M-mutated NSCLC resistant to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors.

Methods

Six cases of resected NSCLC harboring the T790M mutation were examined. We performed miRNA time polymerase chain reaction (PCR) array profiling using EGFR T790M-mutated NSCLC and L858R-mutated NSCLC. Once identified, miRNAs that were differentially expressed between the two groups were validated by quantitative real-time polymerase chain reaction (qRT-PCR).

Results

miRNA PCR array profiling revealed three up-regulated miRNAs whose expression levels were altered 4.0-fold or more in the EGFR T790M mutation group than in the L858R group: miR-1 (fold change, 4.384), miR-196a (fold change, 4.138), and miR-124 (fold change, 4.132). The three differentially expressed miRNAs were validated by qRT-PCR, and they were found to be overexpressed in the T790M group relative to L858R group. In particular, expression levels of miR-1 and miR-124 were significantly higher in the T790M group (p-value of miR-1 = .004, miR-124 = .007, miR-196a = .096).

Conclusions

MiR-1, miR-124, and miR-196a are overexpressed in EGFR T790M mutated NSCLC.

Differential microRNA expression profiles between young and old lung adenocarcinoma patients

Lung cancer is the leading cause of cancer-related mortality, and approximately 80% of cases are non-small cell lung cancer (NSCLC). Recently, the incidence of NSCLC has been quickly increasing, while the age of patients at diagnosis is decreasing. To date, it is still controversial whether younger patients have better or worse outcomes compared with their older counterparts. MicroRNAs (miRNAs) have been defined to play a key role in cancer pathogenesis, and their aberrant expression has been suggested as a potential biomarker of prognosis in lung adenocarcinoma. To understand the molecular features of young and old adenocarcinoma patients, we investigated the expression level of a panel of miRNAs selected after a mini-literature review. The expression analysis was performed by the nCounter System® (NanoString Technologies) directly on RNA, including small RNAs. The analysis revealed that 7 miRNAs (miR-25-3p, miR-29c-3p, miR-33a-5p, miR-144-3p, miR-153-3p, miR-342-5p and miR-485-3p) were differentially expressed in the two groups (P<0.05). All of these miRNAs showed higher expression levels in young compared to old patients, and their predicted targets included EGFR, MET, VEGF-A, TP53 and PDGFRa. miR-144-3p had an opposite influence on overall survival since its upregulation was associated with a worse prognosis in young patients (P=0.01) and with a better outcome in the older group (P=0.03). We observed that lung cancer in young and old patients may be influenced by different regulatory mechanisms. Moreover, one of the down-regulated miRNAs showed a different prognostic impact in the two groups, confirming that young and old patients deserve a specific clinical approach.

MicroRNAs associated with therapy of non-small cell lung cancer

Background & Objective: The incidence of non-small cell lung cancer (NSCLC) has been rising over the past several decades. Despite various therapeutic regimens and modern diagnostic techniques are developed, NSCLC still have an extremely poor prognosis due to drug resistance. Therefore, it is critical to find a novel precise diagnosis and effective treatment approach for NSCLC patients. MicroRNAs (MiRNAs) are a class of 18-25nt non-coding small RNAs, which have been shown to be involved profoundly in the pathogenesis such as cellular proliferation, differentiation, development, apoptosis and tumorigenesis in many human tumors including of NSCLC. We reviewed existing research literature regarding correlations between miRNAs and their target's response to anticancer treatment, and summarized the recent findings between miRNAs and therapy availability in NSCLC.

MiR-29a: a potential therapeutic target and promising biomarker in tumors

MiRNAs, small non-coding RNA molecules, were recognized to be associated with the incidence and development of diverse neoplasms. MiRNAs were small non-coding RNAs that could regulate post-transcriptional level by binding to 3'-UTR of target mRNAs. Amongst which, miR-29a was demonstrated that it had significant impact on oncogenicity in various neoplasms through binding to critical genes which enhanced or inhibited the progression of cancers. MiR-29a participated in kinds of physiological and pathological processes, including virus replication, cell proliferation, differentiation, apoptosis, fibrosis, angiogenesis, tumorigenicity, metastasis, drug-resistance, and so on. According to its sufficient sensitivity and specificity, many studies showed that miR-29a might serve as a potential therapeutic target and promising biomarker in various tumors. In this review, we discussed the functions of miR-29a and its potential application in the diagnosis, treatment and stages of carcinoma, which could provide additional insight to develop a novel therapeutic strategy.

miR-135a Confers Resistance to Gefitinib in Non-Small Cell Lung Cancer Cells by Upregulation of RAC1

The EGFR tyrosine kinase inhibitor gefitinib is used in therapy for non-small cell lung cancer (NSCLC). However, the therapeutic efficacy of gefitinib is known to be impeded by mutations of EGFR. The aim of the present study was to reveal the role of miR-135a in gefitinib resistance of NSCLC cells. Human NSCLC cell lines, NCI-H1650 and NCI-H1975, were transfected with miR-135a mimic/inhibitor or miR-135a inhibitor plus pEX-RAC1 (a RAC1-expressing vector). The effects of miR-135a and RAC1 expression on cell viability, apoptosis, migration, and invasion were then detected. The transfected cells were exposed to 0-20 μM gefitinib, and cell viability was then detected at 48 h posttreatment. Western blot analysis was performed to detect the expression changes of main factors in the PI3K/AKT pathway. miR-135a overexpression promoted viability, migration, and invasion, but inhibited apoptosis of NCI-H1650 and NCI-H1975 cells. Cell viability was significantly reduced by gefitinib, and the LC50 values of gefitinib in NCI-H1650 and NCI-H1795 cells were 0.845 and 0.667 μM, respectively. miR-135a overexpression could increase cell viability even under high concentrations of gefitinib. Rac1 was not predicted as a target of miR-135a, while miR-135a could upregulate the expression of RAC1. miR-135a promoted cell growth and metastasis and activated the PI3K/AKT signaling pathway via a RAC1-dependent manner. To conclude, this study demonstrated that miR-135a confers NSCLC cell resistance to gefitinib via upregulation of RAC1. Therapies designed to downregulate miR-135a may help NSCLC patients to overcome gefitinib resistance.

Development and characterisation of a panel of phosphatidylinositide 3-kinase - mammalian target of rapamycin inhibitor resistant lung cancer cell lines

The PI3K-mTOR pathway is involved in regulating all hallmarks of cancer, and is often dysregulated in NSCLC, making it an attractive therapeutic target in this setting. Acquired resistance to PI3K-mTOR inhibition is a major hurdle to overcome in the success of PI3K-mTOR targeted agents. H460, A549, and H1975 resistant cells were generated by prolonged treatment in culture with Apitolisib (GDC-0980), a dual PI3K-mTOR inhibitor over a period of several months, from age-matched parent cells. Resistance was deemed to have developed when a log fold difference in IC50 had been achieved. Resistant cell lines also exhibited resistance to another widely investigated PI3K-mTOR dual inhibitor; Dactolisib (BEZ235). Cell lines were characterised at the level of mRNA (expression array profiling expression of >150 genes), miRNA (expression array profiling of 2100 miRNAs), protein (bottoms-up label-free mass spectrometry) and phosphoprotein (expression array profiling of 84 phospho/total proteins). Key alterations were validated by qPCR and Western blot. H1975 cells were initially most sensitive to Apitolisib (GDC-0980), but developed resistance more quickly than the other cell lines, perhaps due to increased selective pressure from the impressive initial effect. In-depth molecular profiling suggested epithelial-mesenchymal transition (EMT) may play a role in resistance to PI3K-mTOR dual inhibition in NSCLC.

miR-495 sensitizes MDR cancer cells to the combination of doxorubicin and taxol by inhibiting MDR1 expression

MDR1 is highly expressed in MDR A2780DX5 ovarian cancer cells, MDR SGC7901R gastric cancer cells and recurrent tumours. It pumps cytoplasmic agents out of cells, leading to decreased drug accumulation in cells and making cancer cells susceptible to multidrug resistance. Here, we identified that miR-495 was predicted to target ABCB1, which encodes protein MDR1. To reduce the drug efflux and reverse MDR in cancer cells, we overexpressed a miR-495 mimic in SGC7901R and A2780DX cells and in transplanted MDR ovarian tumours in vivo. The results indicated that the expression of MDR1 in the above cells or tumours was suppressed and that subsequently the drug accumulation in the MDR cells was decreased, cell death was increased, and tumour growth was inhibited after treatment with taxol-doxorubicin, demonstrating increased drug sensitivity. This study suggests that pre-treatment with miR-495 before chemotherapy could improve the curative effect on MDR1-based MDR cancer.

Plasma microRNA alterations between EGFR-activating mutational NSCLC patients with and without primary resistance to TKI

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) have obtained excellent therapeutic effects against non-small cell lung cancer (NSCLC) harboring activating EGFR mutations. However, some patients have exhibited primary resistance which becomes a major obstacle in effective treatment of NSCLC. The mechanisms of EGFR-TKIs resistance involved are still poorly understood. Many studies suggest that miRNAs play an important role in regulating drug sensitivity of EGFR-TKIs. The aim of the present study was to examine differentially expressed miRNAs in plasma between EGFR-TKIs sensitive and EGFR-TKIs primary resistance patients. MiRNA microarray of plasma from patients' blood identified 16 differentially expressed miRNAs of which 15 (hsv2-miR-H19, hsa-miR-744-5p, hsa-miR-3196, hsa-miR-3153, hsa-miR-4791, hsa-miR-4803, hsa-miR-4796-3p, hsa-miR-372-5p, hsa-miR-138-2-3p, hsa-miR-16-1-3p, hsa-miR-1469, hsa-miR-585-3p, ebv-miR-BART14-5p, hsa-miR-769-3p, hsa-miR-548aq-5p) were down regulated while only hsa-miR-503-3p was up regulated in primary resistant patients' plasma. Volcano plot and hierarchical clustering were performed to examine the accuracy of the miRNAs. Then validation with quantitative real-time PCR was performed and the result was in accordance with the array data. Functional analysis of these differentially expressed miRNAs with Ingenuity Pathway Analysis (IPA) revealed a common signaling network including MYC, CCND1, IGF1 and RELA. In conclusion, our finding may play important role in understanding the mechanisms underlying the problem and should be further evaluated as potential biomarkers in primary resistance of NSCLC.

Polyphyllin VII increases sensitivity to gefitinib by modulating the elevation of P21 in acquired gefitinib resistant non-small cell lung cancer

Blockade of EGFR with reversible EGFR tyrosine kinase inhibitors (TKIs) is considered the frontline strategy for advanced NSCLC with EGFR mutations. However, acquired resistance to EGFR-TKI has been observed, resulting in disease progression and limited clinical benefit. Polyphyllin VII is the main member of polyphyllin family, which has been demonstrated to show strong anticancer activity against carcinomas. The sensitizing effect and underlying mechanism of Polyphyllin VII against acquired EGFR-TKI resistant NSCLC are still unexplored. In the present study, we aim to examined the sensitizing effect of Polyphyllin VII to gefitinib by modulating P21 signaling pathway in gefitinib acquired resistant NSCLC in vitro and in vivo. Gefitinib sensitive PC-9 cells and gefitinib acquired resistant H1975 cells were used. Cell proliferation and Clonogenic assay, Cell cycle analysis, Western blotting analysis and xenograft treatment were carried out. Polyphyllin VII enhanced the anti-proliferative effects of gefitinib and gefitinib-induced G1 phase arrest by modulation of P21 signaling pathway in acquired gefitinib resistant cells in vitro and in vivo. Polyphyllin VII elevated sensitization of gefitinib acquired resistant NSCLC cells to gefitinib through G1 phase arrest and modulation of P21 signaling pathway. It provides a potential new strategy to overcome gefitinib acquired resistance for EGFR-TKI resistant NSCLC.

Sensitivity of non-small cell lung cancer to erlotinib is regulated by the Notch/miR-223/FBXW7 pathway

Recent evidence supports a role for microRNA-223 (miR-223) in modulating tumor cell sensitivity to chemotherapeutic drugs; however, its role in cellular resistance to the effects of epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) used in treatment of non-small cell lung cancer (NSCLC) remains to be elucidated. The levels of miR-223 in parental cell line (HCC827) and erlotinib resistant HCC827 cell line (HCC827/ER) were detected by qRT-PCR. HCC827/ER cells were treated with MK-2206 to block the Akt signaling pathway or RO4929097 to block the Notch signaling pathway, and then transfected with an miR-223 inhibitor or interference expression plasmid of F-Box/WD repeat-containing protein 7 (FBXW7) or insulin-like growth factor 1 receptor (IGF1R). HCC827 cells were transfected with miR-223 mimics. Next, CCK-8, colony formation, and flow cytometric apoptosis assays were used to assess cell resistance to erlotinib. When compared with its expression in HCC827 cells, miR-223 expression was significantly up-regulated in HCC827/ER cells. Blocking either the Akt or Notch signaling pathway and reducing miR-223 expression resulted in decreased resistance in HCC827/ER cells. Conversely, increasing miR-223 expression induced cell resistance to erlotinib in HCC827 cells. miR-223 enhanced resistance to erlotinib by down-regulating FBXW7 expression. Reducing FBXW7 expression lowered resistance to erlotinib in HCC827/ER cells, while interference with expression of IGF1R produced no significant effect. This study demonstrated that NSCLC cells can up-regulate their levels of miR-223 expression via the Akt and Notch signaling pathways. miR-223 may serve as an important regulator of erlotinib sensitivity in NSCLC cells by targeting FBXW7.

MiR-30 Family Potentially Targeting PI3K-SIAH2 Predicted Interaction Network Represents a Novel Putative Theranostic Panel in Non-small Cell Lung Cancer

Non-small cell lung cancer (NSCLC) comprises about 84% of all lung cancers. Many treatment options are available but the survival rate is still very low due to drug resistance. It has been found that phosphoinositide-3-kinase (PI3K) affects sensitivity to tyrosine kinase inhibitors (TKIs), including gefitinib and erlotinib. Expression level of seven in absentia homolog 2 (SIAH2), an E3 ubiquitin-protein ligase, is upregulated in NSCLC and correlated with tumor grade. However, the relationship between PI3K and SIAH2 remains unclear and therefore it is not known whether they can act as treatment co-targets and theranostic dual markers for overcoming TKI resistance. It is worthy to note that PI3K and SIAH2 are potentially regulated by a common group of microRNAs in miR-30 family. Our bioinformatics analyses showed upregulated SIAH2 expression in NSCLC based on mass spectrometry data, explored its indirect interaction with PI3K and predicted their targeting microRNAs in common. We have also explored the potential role of miR-30 family in the modulation of PI3K-SIAH2 interaction in NSCLC.

MicroRNA-targeted therapeutics for lung cancer treatment

INTRODUCTION

Lung cancer is one of the leading causes of cancer-related mortality worldwide. MicroRNAs (miRNAs) are endogenous non-coding small RNAs that repress the expression of a broad array of target genes. Many efforts have been made to therapeutically target miRNAs in cancer treatments using miRNA mimics and miRNA antagonists. Areas covered: This article summarizes the recent findings with the role of miRNAs in lung cancer, and discusses the potential and challenges of developing miRNA-targeted therapeutics in this dreadful disease. Expert opinion: The development of miRNA-targeted therapeutics has become an important anti-cancer strategy. Results from both preclinical and clinical trials of microRNA replacement therapy have shown some promise in cancer treatment. However, some obstacles, including drug delivery, specificity, off-target effect, toxicity mediation, immunological activation and dosage determination should be addressed. Several delivery strategies have been employed, including naked oligonucleotides, liposomes, aptamer-conjugates, nanoparticles and viral vectors. However, delivery remains a main challenge in miRNA-targeting therapeutics. Furthermore, immune-related serious adverse events are also a concern, which indicates the complexity of miRNA-based therapy in clinical settings.

miR-346 promotes migration and invasion of nasopharyngeal carcinoma cells via targeting BRMS1

The aim of this study is to determine the expression and roles of miR-346 in nasopharyngeal carcinoma (NPC). We showed that miR-346 was upregulated in NPC tissues compared with adjacent non-tumorous nasopharyngeal tissues. Inhibition of miR-346 significantly attenuated the migration and invasion of NPC cells. Luciferase reporter assay showed that miR-346 targeted the 3'-untranslated region (3'-UTR) of breast cancer metastasis suppressor 1 (BRMS1). Overexpression of miR-346 suppressed the endogenous expression of BRMS1 in NPC cells. There was a significant negative correlation between miR-346 and BRMS1 protein expression in NPC tissues (r = -0.372, P = 0.008). Rescue experiments demonstrated that overexpression of BRMS1 lacking the 3'-UTR impaired the invasiveness of NPC cells transfected with miR-346 mimic. Taken together, miR-346 shows the ability to promote the migration and invasion of nasopharyngeal cancer cells via targeting BRMS1 and represents a potential therapeutic target for NPC.

ATP-binding cassette transmembrane transporters and their epigenetic control in cancer: an overview

INTRODUCTION

Members of the ATP-binding cassette (ABC) transmembrane transporters control the passage of several substrates across cell membranes, including drugs. This means that ABC transporters may exert a significant influence on the kinetics and dynamics of pharmacological agents, being responsible for the occurrence of multidrug-resistant (MDR) phenotype. Pharmacogenetic analyses have shed light on gene expression and polymorphisms as possible markers predictive of transporter activity. However, a non-negligible part of the variability in drug pharmacokinetics and pharmacodynamics still remains. Further research has demonstrated that different epigenetic mechanisms exert a coordinated control over ABC genes, and on the corresponding MDR phenotype. Areas covered: DNA methylation and histone modifications (namely acetylation, methylation, phosphorylation, etc.) significantly impact gene expression, as well as noncoding RNA molecules that are involved in the post-transcriptional control of the ABC transporters ABCB1, ABCC1 and ABCG2. We describe the epigenetic mechanisms of gene expression control for ABC transporters and their relevant association with the MDR phenotype in human cancer. Expert opinion: The clinical meaning of those observations is discussed in the review, highlighting the importance of the epigenetic control of the ABC transporters for the clinical therapeutic outcomes that despite their effects and applications, requires further investigation.