MiR-134/487b/655 cluster regulates TGF-β-induced epithelial-mesenchymal transition and drug resistance to gefitinib by targeting MAGI2 in lung adenocarcinoma cells

Induction of resistance to neurotrophic tropomyosin-receptor kinase inhibitors by HMGCS2 via a mevalonate pathway

INTRODUCTION

A neurotrophic tropomyosin receptor kinase (NTRK)-tyrosine kinase inhibitor (TKI) has shown dramatic efficacy against malignant tumors harboring an NTRK fusion gene. However, almost all tumors eventually acquire resistance to NTRK-TKIs.

METHOD

To investigate the mechanism of resistance to NTRK-TKIs, we established cells resistant to three types of NTRK-TKIs (larotrectinib, entrectinib, and selitrectinib) using KM12 colon cancer cells with a TPM3-NTRK1 rearrangement.

RESULT

Overexpression of 3-hydroxy-3-methylglutaryl-CoA synthase 2 (HMGCS2) was observed in three resistant cells (KM12-LR, KM12-ER, and KM12-SR) by microarray analysis. Lower expression of sterol regulatory element-binding protein 2 (SREBP2) and peroxisome proliferator activated receptor α (PPARα) was found in two cells (KM12-ER and KM12-SR) in which HMGCS2 was overexpressed compared to the parental KM12 and KM12-LR cells. In resistant cells, knockdown of HMGCS2 using small interfering RNA improved the sensitivity to NTRK-TKI. Further treatment with mevalonolactone after HMGCS2 knockdown reintroduced the NTRK-TKI resistance. In addition, simvastatin and silibinin had a synergistic effect with NTRK-TKIs in resistant cells, and delayed tolerance was observed after sustained exposure to clinical concentrations of NTRK-TKI and simvastatin in KM12 cells. In xenograft mouse models, combination treatment with entrectinib and simvastatin reduced resistant tumor growth compared with entrectinib alone.

CONCLUSION

These results suggest that HMGCS2 overexpression induces resistance to NTRK-TKIs via the mevalonate pathway in colon cancer cells. Statin inhibition of the mevalonate pathway may be useful for overcoming this mechanistic resistance.

Efficacy and Mechanisms of Natural Products as Therapeutic Interventions for Chronic Respiratory Diseases

Chronic respiratory diseases are long-term conditions affecting the airways and other lung components that are characterized by a high prevalence, disability rate, and mortality rate. Further optimization of their treatment is required. Natural products, primarily extracted from organisms, possess specific molecular and structural formulas as well as distinct chemical and physical properties. These characteristics grant them the advantages of safety, gentleness, accessibility, and minimal side effects. The numerous advances in the use of natural products for treating chronic respiratory diseases have provided a steady source of motivation for new drug research and development. In this paper, we introduced the pathogenesis of chronic respiratory diseases and natural products. Furthermore, we classified natural products according to their mechanism for treating chronic respiratory diseases and describe the ways in which these products can alleviate the pathological symptoms. Simultaneously, we elaborate on the signal transduction pathways and biological impacts of natural products' targeting. Additionally, we present future prospects for natural products, considering their combination treatment approaches and administration methods. The significance of this review extends to both the research on preventing and treating chronic respiratory diseases, as well as the advancement of novel drug development in this field.

The cell line models to study tyrosine kinase inhibitors in non-small cell lung cancer with mutations in the epidermal growth factor receptor: A scoping review

Non-Small Cell Lung Cancer (NSCLC) represents ∼85% of all lung cancers and ∼15-20% of them are characterized by mutations affecting the Epidermal Growth Factor Receptor (EGFR). For several years now, a class of tyrosine kinase inhibitors was developed, targeting sensitive mutations affecting the EGFR (EGFR-TKIs). To date, the main burden of the TKIs employment is due to the onset of resistance mutations. This scoping review aims to resume the current situation about the cell line models employed for the in vitro evaluation of resistance mechanisms induced by EGFR-TKIs in oncogene-addicted NSCLC. Adenocarcinoma results the most studied NSCLC histotype with the H1650, H1975, HCC827 and PC9 mutated cell lines, while Gefitinib and Osimertinib the most investigated inhibitors. Overall, data collected frame the current advancement of this topic, showing a plethora of approaches pursued to overcome the TKIs resistance, from RNA-mediated strategies to the innovative combination therapies.

MAGI2 ameliorates podocyte apoptosis of diabetic kidney disease through communication with TGF-β-Smad3/nephrin pathway

Podocytes, the key component of the glomerular filtration barrier (GFB), are gradually lost during the progression of diabetic kidney disease (DKD), severely compromising kidney functionality. The molecular mechanisms regulating the survival of podocytes in DKD are incompletely understood. Here, we show that membrane-associated guanylate kinase inverted 2 (MAGI2) is specifically expressed in renal podocytes, and promotes podocyte survival in DKD. We found that MAGI2 expression was downregulated in podocytes cultured with high-glucose in vitro, and in kidneys of db/db mice as well as DKD patients. Conversely, we found enforced expression of MAGI2 via AAV transduction protected podocytes from apoptosis, with concomitant improvement of renal functions. Mechanistically, we found that MAGI2 deficiency induced by high glucose levels activates TGF-β signaling to decrease the expression of anti-apoptotic proteins. These results indicate that MAGI2 protects podocytes from cell death, and can be harnessed therapeutically to improve renal function in diabetic kidney disease.

Current landscape of miRNAs and TGF-β signaling in lung cancer progression and therapeutic targets

Lung cancer (LC) is the primary reason for cancer-associated fatalities globally. Due to both tumor-suppressing and tumor-promoting activities, the TGF-β family of growth factors is extremely essential to tumorigenesis. A non-coding single-stranded short RNA called microRNA (miRNA), which is made up of about 22 nt and is encoded by endogenous genes, can control normal and pathological pathways in various kinds of cancer, including LC. Recent research demonstrated that the TGF-β signaling directly can affect the synthesis of miRNAs through suppressor of mothers against decapentaplegic (SMAD)-dependent activity or other unidentified pathways, which could generate allostatic feedback as a result of TGF-β signaling stimulation and ultimately affect the destiny of cancer tissues. In this review, we emphasize the critical functions of miRNAs in lung cancer progression and, more critically, how they affect the TGF-β signaling pathway, and explore the role of both the TGF-β signaling pathway and miRNAs as potential therapeutic targets for improving the treatments of LC patients.

The crosstalk between non-coding RNA polymorphisms and resistance to lung cancer therapies

Lung cancer (LC) is one of the most common cancer-related mortality in the world. Even with intensive multimodality therapies, lung cancer has a poor prognosis and a high morbidity rate. This review focused on the role of non-coding RNA polymorphisms such as lncRNAs and miRNAs in the resistance to LC therapies, which could open promising avenue for better therapeutic response. Of note, there is currently no valid biomarker to predict lung cancer sensitivity in patients during treatment. Since genetic variations cause many challenges in treating patients, genotyping of known polymorphisms must be thoroughly explored to find desirable treatment platforms. With this knowledge, individualized treatments could become more possible in management of LC.

MicroRNA in lung cancer-a novel potential way for early diagnosis and therapy

Lung cancer is the most common cause of cancer-related deaths in the world. One of the reasons of poor prognosis and high mortality of lung cancer patients is the diagnosis of the disease in its advanced stage. Despite innovative diagnostic methods and multiple completed and ongoing clinical trials aiming at therapy improvement, no significant increase in patients' long-term survival has been noted over last decades. Patients would certainly benefit from early detection of lung cancer. Therefore, it is crucial to find new biomarkers that can help predict outcomes and tumor responses in order to maximize therapy effectiveness and avoid over- or under-treating patients with lung cancer. Nowadays, scientists' attention is mainly dedicated to so-called liquid biopsy, which is fully non-invasive and easily available method based on simple blood draw. Among common liquid biopsy elements, circulating tumor nucleic acids are worth mentioning. Epigenetic biomarkers, particularly miRNA expression, have several distinct features that make them promising prognostic markers. In this review, we described miRNA's involvement in tumorigenesis and present it as a predictor of cancer development and progression, potential indicator of treatment efficacy, and most importantly promising therapeutic target.

AXL in cancer: a modulator of drug resistance and therapeutic target

AXL is a member of the TAM (TYRO3, AXL, and MERTK) receptor tyrosine kinases family (RTKs), and its abnormal expression has been linked to clinicopathological features and poor prognosis of cancer patients. There is mounting evidence supporting AXL's role in the occurrence and progression of cancer, as well as drug resistance and treatment tolerance. Recent studies revealed that reducing AXL expression can weaken cancer cells' drug resistance, indicating that AXL may be a promising target for anti-cancer drug treatment. This review aims to summarize the AXL's structure, the mechanisms regulating and activating it, and its expression pattern, especially in drug-resistant cancers. Additionally, we will discuss the diverse functions of AXL in mediating cancer drug resistance and the potential of AXL inhibitors in cancer treatment.

In silico analysis reveals hypoxia-induced miR-210-3p specifically targets SARS-CoV-2 RNA

Human coronaviruses (HCoVs) until the emergence of SARS in 2003 were associated with mild cold and upper respiratory tract infections. The ongoing pandemic caused by SARS-CoV-2 has enhanced the potential for infection and transmission as compared to other known members of this family. MicroRNAs (miRNA) are 21-25 nucleotides long non-coding RNA that bind to 3' UTR of genes and regulate almost every aspect of cellular function. Several human miRNAs have been known to target viral genomes, mostly to downregulate their expression and sometimes to upregulate also. In some cases, host miRNAs could be sequestered by the viral genome to create a condition for favourable virus existence. The ongoing SARS CoV-2 pandemic is unique based on its transmissibility and severity and we hypothesised that there could be a unique mechanism for its pathogenesis. In this study, we exploited in silico approach to identify human respiratory system-specific miRNAs targeting the viral genome of three highly pathogenic HCoVs (SARS-CoV-2 Wuhan strain, SARS-CoV, and MERS-CoV) and three low pathogenic HCoVs (OC43, NL63, and HKU1). We identified ten common microRNAs that target all HCoVs studied here. In addition, we identified unique miRNAs which targeted specifically one particular HCoV. miR-210-3p was the single unique lung-specific miRNA, which was found to target the NSP3, NSP4, and NSP13 genes of SARS-CoV-2. Further miR-210-NSP3, miR-210-NSP4, and miR-210-NSP13 SARS-CoV-2 duplexes were docked with the hAGO2 protein (PDB ID 4F3T) which showed Z-score values of -1.9, -1.7, and -1.6, respectively. The role of miR-210-3p as master hypoxia regulator and inflammation regulation may be important for SARS-CoV-2 pathogenesis. Overall, this analysis advocates that miR-210-3p be investigated experimentally in SARS-CoV-2 infection.Communicated by Ramaswamy H. Sarma.

miR-134 Up-Regulates Matrix Metalloproteinase 9 (MMP9) in Chronic Sinusitis

Chronic sinusitis is an upper respiratory tract disease. miR-134 involves in several diseases. However, its regulatory mechanism in chronic sinusitis has not been assessed. We aim to explore miR-134’s role in chronic sinusitis and the possible mechanism. miR-134 and MMP9 level was measured in chronic sinusitis tissues and normal tissues. The co-expression of miR-134 and MMP9 in PHNECs was detected by immunofluorescence. MMP-9 expression and IκB and α protein phosphorylation was detected by western blot. Immunofluorescence showed positive MMP-9 expression in epithelial cells. miR-134 level was significantly elevated in patients with chronic sinusitis and was co-localized with MMP-9 in the CRSwNP sample of epithelial cells. miR-134 up-regulated MMP-9, which was inhibited after addition of inhibitor BAY 11-7082. In conclusion, miR-134 up-regulates MMP-9 through NF-κB signaling to mediate the occurrence of chronic sinusitis, indicating that miR-134 may participate in the tissue remodeling of chronic sinusitis.

Inhibitors of ABCB1 and ABCG2 overcame resistance to topoisomerase inhibitors in small cell lung cancer

Background

Small cell lung cancer (SCLC) is a highly aggressive disease with a poor prognosis. Although most patients initially respond to topoisomerase inhibitors, resistance rapidly emerges. The aim, therefore, is to overcome resistance to topoisomerase I (irinotecan) or II (etoposide) inhibitors in SCLCs.

Methods

To identify key factors in the chemoresistance of SCLCs, we established four cell lines resistant to etoposide or an active metabolite of irinotecan, SN‐38, from SCLC cell lines and evaluated RNA profiles using parental and newly established cell lines.

Results

We found that the drug efflux protein, ATP‐binding cassette sub‐family B member 1 (ABCB1), was associated with resistance to etoposide, and ATP‐binding cassette sub‐family G member 2 (ABCG2) was associated with resistance to SN‐38 by RNA sequencing. The inhibition of ABCB1 or ABCG2 in each resistant cell line induced synergistic apoptotic activity and promoted drug sensitivity in resistant SCLC cells. The ABC transporter inhibitors, elacridar and tariquidar, restored sensitivity to etoposide or SN‐38 in in vitro and in vivo studies, and promoted apoptotic activity and G2‐M arrest in resistant SCLC cells.

Conclusions

ABC transporter inhibitors may be a promising therapeutic strategy for the purpose of overcoming resistance to topoisomerase inhibitors in patients with SCLC.

Cell Behavior of Non-Small Cell Lung Cancer Is at EGFR and MicroRNAs Hands

Lung cancer is a complex disease associated with gene mutations, particularly mutations of Kirsten Rat Sarcoma Viral Oncogene Homolog (KRAS) and epidermal growth factor receptor (EGFR). Non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC) are the two major types of lung cancer. The former includes most lung cancers (85%) and are commonly associated with EGFR mutations. Several EGFR-tyrosine kinase inhibitors (EGFR-TKIs), including erlotinib, gefitinib, and osimertinib, are effective therapeutic agents in EGFR-mutated NSCLC. However, their effectiveness is limited by the development (acquired) or presence of intrinsic drug resistance. MicroRNAs (miRNAs) are key gene regulators that play a profound role in the development and outcomes for NSCLC via their role as oncogenes or oncosuppressors. The regulatory role of miRNA-dependent EGFR crosstalk depends on EGFR signaling pathway, including Rat Sarcoma/Rapidly Accelerated Fibrosarcoma/Mitogen-Activated Protein Kinase/Extracellular Signal-Regulated Kinase 1/2 (Ras/Raf/MEK/ERK1/2), Signal Transducer and Activator of Transcription (STAT), Nuclear Factor Kappa-Light-Chain-Enhancer of Activated B Cells (NF-kB), phosphoinositide 3-kinase/protein kinase B (PI3K/AKT), Janus kinase 1 (JAK1), and growth factor receptor-bound protein 2 (GRB2). Dysregulated expression of miRNAs affects sensitivity to treatment with EGFR-TKIs. Thus, abnormalities in miRNA-dependent EGFR crosstalk can be used as diagnostic and prognostic markers, as well as therapeutic targets in NSCLC. In this review, we present an overview of miRNA-dependent EGFR expression regulation, which modulates the behavior and progression of NSCLC.

Genetic variants of SDCCAG8 and MAGI2 in mitosis-related pathway genes are independent predictors of cutaneous melanoma-specific survival

Mitosis is a prognostic factor for cutaneous melanoma (CM), but accurate mitosis detection in CM tissues is difficult. Therefore, the 8th Edition of the American Joint Committee on Cancer staging system has removed the mitotic rate as a category criterion of the tumor T-category, based on the evidence that the mitotic rate was not an independent prognostic factor for melanoma survival. As single-nucleotide polymorphisms (SNPs) have been shown to be potential predictors for cutaneous melanoma-specific survival (CMSS), we investigated the potential prognostic value of SNPs in mitosis-related pathway genes in CMSS by analyzing their associations with outcomes of 850 CM patients from The University of Texas MD Anderson Cancer Center in a discovery dataset and validated the findings in another dataset of 409 CM patients from the Harvard University Nurses' Health Study and Health Professionals Follow-up Study. In both datasets, we identified two SNPs (SDCCAG8 rs10803138 G>A and MAGI2 rs3807694 C>T) as independent prognostic factors for CMSS, with adjusted allelic hazards ratios of 1.49 (95% confidence interval = 1.17-1.90, P = .001) and 1.45 (1.13-1.86, P = .003), respectively. Furthermore, their combined unfavorable alleles also predicted a poor survival in both discovery and validation datasets in a dose-response manner (Ptrend  = .0006 and .0001, respectively). Additional functional analysis revealed that both SDCCAG8 rs10803138 A and MAGI2 rs3807694 T alleles were associated with elevated mRNA expression levels in normal tissues. Therefore, these findings suggest that SDCCAG8 rs10803138 G>A and MAGI2 rs3807694 C>T are independent prognostic biomarkers for CMSS, possibly by regulating the mRNA expression of the corresponding genes involved in mitosis.

A New Story of the Three Magi: Scaffolding Proteins and lncRNA Suppressors of Cancer

Scaffolding molecules exert a critical role in orchestrating cellular response through the spatiotemporal assembly of effector proteins as signalosomes. By increasing the efficiency and selectivity of intracellular signaling, these molecules can exert (anti/pro)oncogenic activities. As an archetype of scaffolding proteins with tumor suppressor property, the present review focuses on MAGI1, 2, and 3 (membrane-associated guanylate kinase inverted), a subgroup of the MAGUK protein family, that mediate networks involving receptors, junctional complexes, signaling molecules, and the cytoskeleton. MAGI1, 2, and 3 are comprised of 6 PDZ domains, 2 WW domains, and 1 GUK domain. These 9 protein binding modules allow selective interactions with a wide range of effectors, including the PTEN tumor suppressor, the β-catenin and YAP1 proto-oncogenes, and the regulation of the PI3K/AKT, the Wnt, and the Hippo signaling pathways. The frequent downmodulation of MAGIs in various human malignancies makes these scaffolding molecules and their ligands putative therapeutic targets. Interestingly, MAGI1 and MAGI2 genetic loci generate a series of long non-coding RNAs that act as a tumor promoter or suppressor in a tissue-dependent manner, by selectively sponging some miRNAs or by regulating epigenetic processes. Here, we discuss the different paths followed by the three MAGIs to control carcinogenesis.

MAGI1, a Scaffold Protein with Tumor Suppressive and Vascular Functions

MAGI1 is a cytoplasmic scaffolding protein initially identified as a component of cell-to-cell contacts stabilizing cadherin-mediated cell–cell adhesion in epithelial and endothelial cells. Clinical-pathological and experimental evidence indicates that MAGI1 expression is decreased in some inflammatory diseases, and also in several cancers, including hepatocellular carcinoma, colorectal, cervical, breast, brain, and gastric cancers and appears to act as a tumor suppressor, modulating the activity of oncogenic pathways such as the PI3K/AKT and the Wnt/β-catenin pathways. Genomic mutations and other mechanisms such as mechanical stress or inflammation have been described to regulate MAGI1 expression. Intriguingly, in breast and colorectal cancers, MAGI1 expression is induced by non-steroidal anti-inflammatory drugs (NSAIDs), suggesting a role in mediating the tumor suppressive activity of NSAIDs. More recently, MAGI1 was found to localize at mature focal adhesion and to regulate integrin-mediated adhesion and signaling in endothelial cells. Here, we review MAGI1′s role as scaffolding protein, recent developments in the understanding of MAGI1 function as tumor suppressor gene, its role in endothelial cells and its implication in cancer and vascular biology. We also discuss outstanding questions about its regulation and potential translational implications in oncology.

MicroRNA-134 inhibits tumor stem cell migration and invasion in oral squamous cell carcinomas via downregulation of PI3K-Akt signaling pathway by inhibiting LAMC2 expression

BACKGROUND

Oral squamous cell carcinoma (OSCC) is the most common malignant neoplasm of the mouth. Some studies have found that multiple microRNAs (miRs) participate in OSCC physiological and pathological processes.

METHODS

We explored the mechanism of action of miR-134 in OSCC involving the PI3K-Akt signaling pathway. Different bioinformatics methods were used to analyze the potential genes and their related miRs in OSCC. Tumor stem cells were separated from OSCCs through magnetic cell sorting. Regulatory pattern between miR-134 and LAMC2 in OSCC was evaluated by ectopic expression, knockdown and reporter assay experiments. The expression of miR-134, LAMC2, genes in PI3K-Akt signaling pathway, and apoptosis-related genes was detected. Cell proliferation was assessed by MTT assay, cell invasion by scratch test, cell migration by Transwell assay, cell cycle and apoptosis by flow cytometry, and cell growth and migration by xenograft tumor in nude mice. LAMC2 was predicted as the crucial factor related to OSCC using different chip data, and miR-134 was predicted to specifically bind LAMC2 in all five databases.

RESULTS

Overexpressed miR-134 or silenced LAMC2 was observed to inhibit cell proliferation, migration, invasion of OSCC cells, growth of subcutaneous xenograft in nude mice, as well as promote OSCC cell apoptosis. LAMC2, a target gene of miR-134, decreased following miR-134 promotion, while the PI3K-Akt signaling pathway was inactivated following LAMC2 knockdown. Furthermore, we also observed that the effect of overexpressed miR-134 was enhanced when LAMC2 was knocked down.

CONCLUSIONS

Taken together, these findings suggest that miR-134-mediated direct downregulation of LAMC2 inhibits migration and invasion of tumor stem cells in OSCC by suppressing the PI3K-Akt signaling pathway.

MiR-134, Mediated by IRF1, Suppresses Tumorigenesis and Progression by Targeting VEGFA and MYCN in Osteosarcoma

BACKGROUND

Osteosarcoma (OS) is a prevalent primary bone malignancy and its distal metastasis remains the main cause of mortality in OS patients. MicroRNAs (miRNAs) play critical roles during cancer metastasis.

OBJECTIVE

Thus, elucidating the role of miRNA dysregulation in OS metastasis may provide novel therapeutic targets.

METHODS

The previous study found a low miR-134 expression level in the OS specimens compared with paracancer tissues. Overexpression of miR-134 stable cell lines was established. Cell viability assay, cell invasion and migration assay and apoptosis assay were performed to evaluate the role of miR-134 in OS in vitro.

RESULTS

We found that miR-134 overexpression inhibits cell proliferation, migration and invasion, and induces cell apoptosis in both MG63 and Saos-2 cell lines. Mechanistically, miR-134 targets the 3'-UTR of VEGFA and MYCN mRNA to silence its translation, which was confirmed by luciferase-reporter assay. The real-time PCR analysis illustrated that miR-134 overexpression decreases VEGFA and MYCN mRNA levels. Additionally, the overexpression of VEGFA or MYCN can partly attenuate the effects of miR-134 on OS cell migration and viability. Furthermore, the overexpression of miR-134 dramatically inhibits tumor growth in the human OS cell line xenograft mouse model in vivo. Moreover, bioinformatic and luciferase assays indicate that the expression of miR-134 is regulated by Interferon Regulatory Factor (IRF1), which binds to its promoter and activates miR-134 expression.

CONCLUSION

Our study demonstrates that IRF1 is a key player in the transcriptional control of miR-134, and it inhibits cell proliferation, invasion and migration in vitro and in vivo via targeting VEGFA and MYCN.

Cancer drug resistance induced by EMT: novel therapeutic strategies

Over the last decade, important clinical benefits have been achieved in cancer patients by using drug-targeting strategies. Nevertheless, drug resistance is still a major problem in most cancer therapies. Epithelial-mesenchymal plasticity (EMP) and tumour microenvironment have been described as limiting factors for effective treatment in many cancer types. Moreover, epithelial-to-mesenchymal transition (EMT) has also been associated with therapy resistance in many different preclinical models, although limited evidence has been obtained from clinical studies and clinical samples. In this review, we particularly deepen into the mechanisms of which intermediate epithelial/mesenchymal (E/M) states and its interconnection to microenvironment influence therapy resistance. We also describe how the use of bioinformatics and pharmacogenomics will help to figure out the biological impact of the EMT on drug resistance and to develop novel pharmacological approaches in the future.

Exosome-derived miR-210 involved in resistance to osimertinib and epithelial-mesenchymal transition in EGFR mutant non-small cell lung cancer cells

Background

Osimertinib is a third‐generation epidermal growth factor receptor‐tyrosine kinase inhibitor (EGFR‐TKI) approved for the treatment of patients with EGFR‐mutant non‐small cell lung cancer (NSCLC). However, the mechanisms of acquired drug resistance to osimertinib have not as yet been clarified. Exosomes and microRNAs (miRNAs) are involved in carcinogenesis and drug resistance in human cancers.

Methods

We used previously established osimertinib‐resistant HCC827 (HCC827‐OR) and PC‐9 (PC‐9‐OR) cells. We evaluated the profiles of exosomal miRNA associated with resistance to osimertinib in EGFR‐mutant NSCLC cells.

Results

Epithelial–mesenchymal transition (EMT) phenomenon was observed in HCC827‐OR and PC‐9‐OR cells. Microarray and quantitative reverse transcription‐polymerase chain reaction analysis revealed that miR‐210‐3p was co‐upregulated in exosomes isolated from HCC827‐OR and PC‐9‐OR cells compared with those isolated from parental HCC827 and PC‐9 cells. HCC827‐OR cell‐derived exosomes induced EMT changes and resistance to osimertinib in HCC827 cells. Subsequently, the induction of miR‐210‐3p directly promoted the EMT phenomenon and resistance to osimertinib in HCC827 cells.

Conclusions

Exosomal miR‐210‐3p may play a crucial role in resistance to osimertinib in the tumor microenvironment of EGFR‐mutant NSCLC.

Long Non-Coding RNA CRNDE Is Involved in Resistance to EGFR Tyrosine Kinase Inhibitor in EGFR-Mutant Lung Cancer via eIF4A3/MUC1/EGFR Signaling

(1) Background: Acquired resistance to epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) is an intractable problem for many clinical oncologists. The mechanisms of resistance to EGFR-TKIs are complex. Long non-coding RNAs (lncRNAs) may play an important role in cancer development and metastasis. However, the biological process between lncRNAs and drug resistance to EGFR-mutated lung cancer remains largely unknown. (2) Methods: Osimertinib- and afatinib-resistant EGFR-mutated lung cancer cells were established using a stepwise method. A microarray analysis of non-coding and coding RNAs was performed using parental and resistant EGFR-mutant non-small cell lung cancer (NSCLC) cells and evaluated by bioinformatics analysis through medical-industrial collaboration. (3) Results: Colorectal neoplasia differentially expressed (CRNDE) and DiGeorge syndrome critical region gene 5 (DGCR5) lncRNAs were highly expressed in EGFR-TKI-resistant cells by microarray analysis. RNA-protein binding analysis revealed eukaryotic translation initiation factor 4A3 (eIF4A3) bound in an overlapping manner to CRNDE and DGCR5. The CRNDE downregulates the expression of eIF4A3, mucin 1 (MUC1), and phospho-EGFR. Inhibition of CRNDE activated the eIF4A3/MUC1/EGFR signaling pathway and apoptotic activity, and restored sensitivity to EGFR-TKIs. (4) Conclusions: The results showed that CRNDE is associated with the development of resistance to EGFR-TKIs. CRNDE may be a novel therapeutic target to conquer EGFR-mutant NSCLC.

Small in Size, but Large in Action: microRNAs as Potential Modulators of PTEN in Breast and Lung Cancers

MicroRNAs (miRNAs) are well-known regulators of biological mechanisms with a small size of 19–24 nucleotides and a single-stranded structure. miRNA dysregulation occurs in cancer progression. miRNAs can function as tumor-suppressing or tumor-promoting factors in cancer via regulating molecular pathways. Breast and lung cancers are two malignant thoracic tumors in which the abnormal expression of miRNAs plays a significant role in their development. Phosphatase and tensin homolog (PTEN) is a tumor-suppressor factor that is capable of suppressing the growth, viability, and metastasis of cancer cells via downregulating phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) signaling. PTEN downregulation occurs in lung and breast cancers to promote PI3K/Akt expression, leading to uncontrolled proliferation, metastasis, and their resistance to chemotherapy and radiotherapy. miRNAs as upstream mediators of PTEN can dually induce/inhibit PTEN signaling in affecting the malignant behavior of lung and breast cancer cells. Furthermore, long non-coding RNAs and circular RNAs can regulate the miRNA/PTEN axis in lung and breast cancer cells. It seems that anti-tumor compounds such as baicalein, propofol, and curcumin can induce PTEN upregulation by affecting miRNAs in suppressing breast and lung cancer progression. These topics are discussed in the current review with a focus on molecular pathways.

EMT-associated microRNAs and their roles in cancer stemness and drug resistance

Epithelial‐to‐mesenchymal transition (EMT) is implicated in a wide array of malignant behaviors of cancers, including proliferation, invasion, and metastasis. Most notably, previou studies have indicated that both cancer stem‐like properties and drug resistance were associated with EMT. Furthermore, microRNAs (miRNAs) play a pivotal role in the regulation of EMT phenotype, as a result, some miRNAs impact cancer stemness and drug resistance. Therefore, understanding the relationship between EMT‐associated miRNAs and cancer stemness/drug resistance is beneficial to both basic research and clinical treatment. In this review, we preliminarily looked into the various roles that the EMT‐associated miRNAs play in the stem‐like nature of malignant cells. Then, we reviewed the interaction between EMT‐associated miRNAs and the drug‐resistant complex signaling pathways of multiple cancers including lung cancer, gastric cancer, gynecologic cancer, breast cancer, liver cancer, colorectal cancer, pancreatic cancer, esophageal cancer, and nasopharyngeal cancer. We finally discussed the relationship between EMT, cancer stemness, and drug resistance, as well as looked forward to the potential applications of miRNA therapy for malignant tumors.

Molecular mechanisms of astragaloside‑IV in cancer therapy (Review)

Radix Astragali (RA) is widely used in traditional Chinese medicine (TCM), and astragaloside IV (AS-IV) is the most critical component of RA. Previous studies have demonstrated that AS-IV exerts effects on the myocardium, nervous system and endocrine system, among others. In the present review article, data from studies conducted over the past 20 years were collated, which have evaluated the effects of AS-IV on tumors. The mechanisms of action of AS-IV on malignant cells both in vivo and in vitro were summarized and it was demonstrated that AS-IV plays a vital role, particularly in inhibiting tumor growth and metastasis, promoting the apoptosis of tumor cells, enhancing immune function and preventing drug resistance. Moreover, AS-IV controls several epithelial-mesenchymal transformation (EMT)-related and autophagy-related pathways, such as the phosphoinositide-3-kinase (PI3K)/protein kinase B (AKT), Wnt/β-catenin, mitogen-activated protein kinase (MAPK)/extracellular regulated protein kinase (ERK) and transforming growth factor-β (TGF-β)/SMAD signaling pathways, which are commonly affected in the majority of tumors. The present review provides new perspectives on the functions of AS-IV and its role as an adjuvant treatment in cancer chemotherapy.

Flavonoid display ability to target microRNAs in cancer pathogenesis

MicroRNAs (miRNAs) are non-coding, conserved, single-stranded nucleotide sequences involved in physiological and developmental processes. Recent evidence suggests an association between miRNAs' deregulation with initiation, promotion, progression, and drug resistance in cancer cells. Besides, miRNAs are known to regulate the epithelial-mesenchymal transition, angiogenesis, autophagy, and senescence in different cancer types. Previous reports proposed that apart from the antioxidant potential, flavonoids play an essential role in miRNAs modulation associated with changes in cancer-related proteins, tumor suppressor genes, and oncogenes. Thus, flavonoids can suppress proliferation, help in the development of drug sensitivity, suppress metastasis and angiogenesis by modulating miRNAs expression. In the present review, we summarize the role of miRNAs in cancer, drug resistance, and the chemopreventive potential of flavonoids mediated by miRNAs. The potential of flavonoids to modulate miRNAs expression in different cancer types demonstrate their selectivity and importance as regulators of carcinogenesis. Flavonoids as chemopreventive agents targeting miRNAs are extensively studied in vitro, in vivo, and pre-clinical studies, but their efficiency in targeting miRNAs in clinical studies is less investigated. The evidence presented in this review highlights the potential of flavonoids in cancer prevention/treatment by regulating miRNAs, although further investigations are required to validate and establish their clinical usefulness.

Long noncoding RNA MAGI2-AS3 inhibits bladder cancer progression through MAGI2/PTEN/epithelial-mesenchymal transition (EMT) axis

BACKGROUND

Long noncoding RNA (lncRNA) are critical regulators of tumor progression.

OBJECTIVE

To determine how the lncRNA membrane associated guanylate kinase, WW and PDZ domain-containing 2 (MAG12) antisense RNA 3 (MAGI2-AS3) and the phosphatase and tensin homolog (PTEN) gene function in regulating bladder cancer (Bca) progression.

METHODS

Total RNA from 80 Bca tissues and 30 paired para-cancerous tissues from patients was sequentially extracted, quantified, purified, and reverse transcribed using RT-PCR. A library was constructed and sequenced. Four Bca cell lines and a normal urothelial cell line were transfected with lentiviral plasmids, and cell migration and invasion were assayed in vitro. An orthotopic mouse model of Bca was created for in vivo studies.

RESULTS

MAGI2-AS3 expression was significantly downregulated in Bca, compared with normal tissues, and negatively associated with tumor stage and a poor prognosis. MAGI2-AS3 and its sense RNA MAGI2 showed significant and positive correlation. The expression of MAGI2 and its downstream gene, PTEN, increased in Bca cells overexpressing MAGI2-AS3, and interference by MAGI2 expression reversed the migration and invasion inhibited by MAGI2-AS3 overexpression.

CONCLUSION

MAGI2-AS3 overexpression inhibited Bca cell progression by regulating the MAGI2/PTEN/epithelial-mesenchymal transition, offering novel insights into the mechanism of Bca progression.

Long noncoding RNA plasmacytoma variant translocation gene 1 promotes epithelial-mesenchymal transition in osteosarcoma

Objective

Long noncoding RNAs (lncRNAs) are involved in the proliferation, migration, and invasion of tumors. In the current study, our aim was to explore the role of lncRNA plasmacytoma variant translocation gene 1 (PVT1) in osteosarcoma.

Methods

Quantitative real‐time reverse transcription‐polymerase chain reaction was used to detect the expression of lncRNA PVT1 in osteosarcoma tissues and cells. The relationship between lncRNA PVT1 expression status and the prognosis of patients with osteosarcoma was analyzed. The effect of lncRNA PVT1 on the malignant biological behavior of osteosarcoma cells in vitro was also analyzed.

Results

LncRNA PVT1 was upregulated in osteosarcoma. High lncRNA PVT1 expression indicated poor prognosis in patients with osteosarcoma. In vitro knockdown of lncRNA PVT1 inhibited the proliferation, migration, and invasion ability of osteosarcoma cells. In addition, we confirmed that lncRNA PVT1 affected the epithelial‐mesenchymal transition of osteosarcoma cells.

Conclusion

LncRNA PVT1 is a potential therapeutic target for osteosarcoma.

1,25-dihydroxyvitamin D3 signaling-induced decreases in IRX4 inhibits NANOG-mediated cancer stem-like properties and gefitinib resistance in NSCLC cells

Recent studies have demonstrated that acquisition of cancer stem-like properties plays an essential role in promoting epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) resistance in non-small cell lung cancer (NSCLC); however, how to regulate cancer stem-like properties and EGFR-TKI resistance is largely unclear. In this study, we discovered that increased iroquois-class homeodomain protein 4 (IRX4) was related to gefitinib resistance in NSCLC cells. Knockdown of IRX4 inhibited cell proliferation, sphere formation, and the expression of CD133, ALDH1A1, NANOG, Sox2 and Notch1, and the transcriptional activity of NANOG promoter. IRX4 overexpression increased the protein level of NANOG and CD133 in PC-9 cells. Combination of knocking-down IRX4 with gefitinib increased cell apoptosis and decreased cell viability and the expression of p-EGFR and NANOG in PC-9/GR cells. IRX4 knockdown in a PC-9/GR xenograft tumor model inhibited tumor progression and the expression of NANOG and CD133 more effectively than single treatment alone. Knockdown of NANOG inhibited the expression of CD133 and restored gefitinib cytotoxicity, and NANOG overexpression-induced cancer stem-like properties and gefitinib resistance could be obviously reversed by knocking-down IRX4. Further, we found that 1,25-dihydroxyvitamin D3 (1,25(OH)₂D₃) reduced obviously the expression of IRX4 and NANOG by inhibiting the activation of TGF-β1/Smad3 signaling pathway; moreover, combination of 1,25(OH)₂D₃ and gefitinib decreased cell viability and proliferation or tumor progression and the expression of IRX4 and NANOG compared with single treatment alone both in PC-9/GR cells and in a PC-9/GR xenograft tumor model. These results reveal that inhibition of IRX4-mediated cancer stem-like properties by regulating 1,25(OH)₂D₃ signaling may increase gefitinib cytotoxicity. Combination therapy of gefitinib and 1,25(OH)₂D₃ by targeting IRX4 and NANOG, could provide a promising strategy to improve gefitinib cytotoxicity.

Endoplasmic reticulum stress-induced exosomal miR-27a-3p promotes immune escape in breast cancer via regulating PD-L1 expression in macrophages

Immune escape of breast cancer cells contributes to breast cancer pathogenesis. Tumour microenvironment stresses that disrupt protein homeostasis can produce endoplasmic reticulum (ER) stress. The miRNA‐mediated translational repression of mRNAs has been extensively studied in regulating immune escape and ER stress in human cancers. In this study, we identified a novel microRNA (miR)‐27a‐3p and investigated its mechanistic role in promoting immune evasion. The binding affinity between miR‐27a‐3p and MAGI2 was predicted using bioinformatic analysis and verified by dual‐luciferase reporter assay. Ectopic expression and inhibition of miR‐27a‐3p in breast cancer cells were achieved by transduction with mimics and inhibitors. Besides, artificial modulation of MAGI2 and PTEN was done to explore their function in ER stress and immune escape of cancer cells. Of note, exosomes were derived from cancer cells and co‐cultured with macrophages for mechanistic studies. The experimental data suggested that ER stress biomarkers including GRP78, PERK, ATF6, IRE1α and PD‐L1 were overexpressed in breast cancer tissues relative to paracancerous tissues. Endoplasmic reticulum stress promoted exosome secretion and elevated exosomal miR‐27a‐3p expression. Elevation of miR‐27a‐3p and PD‐L1 levels in macrophages was observed in response to exosomes‐overexpressing miR‐27a‐3p in vivo and in vitro. miR‐27a‐3p could target and negatively regulate MAGI2, while MAGI2 down‐regulated PD‐L1 by up‐regulating PTEN to inactivate PI3K/AKT signalling pathway. Less CD4⁺, CD8⁺ T cells and IL‐2, and T cells apoptosis were observed in response to co‐culture of macrophages and CD3⁺ T cells. Conjointly, exosomal miR‐27a‐3p promotes immune evasion by up‐regulating PD‐L1 via MAGI2/PTEN/PI3K axis in breast cancer.

miR-365a-5p suppresses gefitinib resistance in non-small-cell lung cancer through targeting PELI3

Aim: Demonstrate the function of dysregulated miR-365a-5p-PELI3 signaling axis in the generation of gefitinib resistance during treatment for non-small-cell lung cancer (NSCLC). Patients & methods: All the NSCLC patients who participated in this research were recruited from the Second Hospital of Hebei Medical University. PC9 cells and PC9GR cells were cultured for in vitro experiments. Results: Patients who were primary resistant to EGFR-tyrosine kinase inhibitor had lower miR-365a-5p levels. MiR-365a-5p directly targeted PELI3 mRNA. MiR-365a-5p overexpression enhanced the function of gefitinib in inhibiting cell viability. Tumor growth was suppressed through miR-365a-5p in nude mice. Conclusion: Dysregulated miR-365a-5p-PELI3 signaling axis triggered the generation of gefitinib resistance in NSCLC.

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.

miR‑10a increases the cisplatin resistance of lung adenocarcinoma circulating tumor cells via targeting PIK3CA in the PI3K/Akt pathway

Circulating tumor cells (CTCs) that are shed from the primary tumor invade the blood stream or surrounding parenchyma to form new tumors. The present study aimed to explore the underlying mechanism of cisplatin resistance in lung adenocarcinoma CTCs and provide clinical treatment guidance for lung cancer treatment. CTCs from the blood samples of 6 lung adenocarcinoma patients were treated with different concentrations of cisplatin along with A549 and H1299 cells. The sensitivity of CTCs to cisplatin was explored by detecting the inhibitory rate via CCK‑8 assay. The related molecular mechanism was investigated by western blot analysis. miR‑10a expression was detected using quantitative real‑time PCR (RT‑qPCR). The relationship between miR‑10a and phosphatidylinositol‑4,5‑bisphosphate 3‑kinase catalytic subunit α (PIK3CA) was verified and further confirmed by luciferase reporter assay, western blotting and RT‑qPCR assay. The results revealed that CTCs exhibited lower cisplatin sensitivity than A549 and H1299 cells. Moreover, CTCs treated with cisplatin demonstrated higher miR‑10a expression and lower PIK3CA expression than that in A549 and H1299 cells (P<0.01). Expression of phosphoinositide 3‑kinase (PI3K) and protein kinase B (Akt) phosphorylation were also decreased in A549 and H1299 cells compared with CTCs after cisplatin treatment. PIK3CA is a target of miR‑10a, and both miR‑10a overexpression and PIK3CA knockdown obviously decreased the sensitivity of A549 and H1299 cells to cisplatin as well as the expression of PI3K and phosphorylation of Akt. PIK3CA overexpression attenuated the cisplatin resistance of A549 and H1299 cells induced by miR‑10a. In conclusion, miR‑10a suppressed the PI3K/Akt pathway to strengthen the resistance of CTCs to cisplatin via targeting PIK3CA, providing a new therapeutic target for lung cancer treatment.

Crosstalk between Epidermal Growth Factor Receptors (EGFR) and integrins in resistance to EGFR tyrosine kinase inhibitors (TKIs) in solid tumors

Cell adhesion to the extracellular matrix (ECM) is important in a variety of physiological and pathologic processes, including development, tumor invasion, and metastasis. Integrin-mediated attachment to ECM proteins has emerged to cue events primitively important for the transformed phenotype of human cancer cells. Cross-talk between integrins and growth factor receptors takes an increasingly prominent role in defining adhesion, motility, and cell growth. This functional interaction has expanded beyond to link integrins with resistance to Tyrosine kinase inhibitors (TKIs) of Epidermal Growth Factor Receptors (EGFRs). In this regard, integrin-mediated adhesion has two separate functions one as a clear collaborator with growth factor receptor signaling and the second as a basic mechanism contributing in Epithelial to Mesenchymal Transition (EMT) which affects response to chemotherapy. This review provides an overview of these mechanisms and describes treatment options for selectively targeting and disrupting integrin interaction to EGFR for cancer therapy.

Novel Liquid Biomarker Panels for A Very Early Response Capturing of NSCLC Therapies in Advanced Stages

Computed tomography (CT) scans are the gold standard to measure treatment success of non-small cell lung cancer (NSCLC) therapies. Here, we investigated the very early tumor response of patients receiving chemotherapy or targeted therapies using a panel of already established and explorative liquid biomarkers. Blood samples from 50 patients were taken at baseline and at three early time points after therapy initiation. DNA mutations, a panel of 17 microRNAs, glycodelin, glutathione disulfide, glutathione, soluble caspase-cleaved cytokeratin 18 (M30 antigen), and soluble cytokeratin 18 (M65 antigen) were measured in serum and plasma samples. Baseline and first follow-up CT scans were evaluated and correlated with biomarker data. The detection rate of the individual biomarkers was between 56% and 100%. While only keratin 18 correlated with the tumor load at baseline, we found several individual markers correlating with the tumor response to treatment for each of the three time points of blood draws. A combination of the five best markers at each time point resulted in highly significant marker panels indicating therapeutic response (R² = 0.78, R² = 0.71, and R² = 0.71). Our study demonstrates that an early measurement of biomarkers immediately after therapy start can assess tumor response to treatment and might support an adaptation of treatment to improve patients’ outcome.

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.

miR-487b and TRAK2 that form an axis to regulate the aggressiveness of osteosarcoma, are potential therapeutic targets and prognostic biomarkers

To investigate the effect of microRNA-487b (miR-487b) as well as the underlying mechanism in osteosarcoma (OS). Data downloaded from the Gene Expression Omnibus (GEO) database were used to analyze the expression and prognostic value of miR-487b/TRAK2. Cell counting kit-8, colony formation, and transwell assays were performed to investigate the biological functions of miR-487b and TRAK2. Luciferase reporter assay was applied to confirm the interactions between miR-487b and TRAK2. miR-487b was overexpressed in OS tissues and was inversely associated with the prognosis of OS patients. We discovered that miR-487b could contribute to the proliferative, clonogenic, invasive, and migratory capabilities of OS cells. Through target prediction using miRWalk and differential expression analysis based on the GEO data set, trafficking kinesin protein 2 (TRAK2) was recognized as a potential target of miR-487b, which was further verified by luciferase reporter assay. The expression of TRAK2 was decreased in OS tissues compared with normal tissues and was positively correlated with the prognosis of OS patients. A negative relevance was presented between the expression of miR-487b and TRAK2 in OS cells. Of note, further mechanistic analyses indicated that TRAK2 was implicated in the regulatory effect of miR-487b on the cell malignant behaviors in OS. To sum up, these results demonstrated that miR-487b played an oncogenic role in OS progression via directly targeting TRAK2, which could advance the development of cancer treatment.

MiRNAs and LncRNAs: Dual Roles in TGF-β Signaling-Regulated Metastasis in Lung Cancer

Lung cancer is one of the most malignant cancers around the world, with high morbidity and mortality. Metastasis is the leading cause of lung cancer deaths and treatment failure. MicroRNAs (miRNAs) and long non-coding RNAs (lncRNAs), two groups of small non-coding RNAs (nc-RNAs), are confirmed to be lung cancer oncogenes or suppressors. Transforming growth factor-β (TGF-β) critically regulates lung cancer metastasis. In this review, we summarize the dual roles of miRNAs and lncRNAs in TGF-β signaling-regulated lung cancer epithelial-mesenchymal transition (EMT), invasion, migration, stemness, and metastasis. In addition, lncRNAs, competing endogenous RNAs (ceRNAs), and circular RNAs (circRNAs) can act as miRNA sponges to suppress miRNAs, thereby mediating TGF-β signaling-regulated lung cancer invasion, migration, and metastasis. Through this review, we hope to cast light on the regulatory mechanisms of miRNAs and lncRNAs in TGF-β signaling-regulated lung cancer metastasis and provide new insights for lung cancer treatment.

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.

MAGI1, a New Potential Tumor Suppressor Gene in Estrogen Receptor Positive Breast Cancer

Membrane-associated guanylate kinase (MAGUK) with inverted domain structure-1 (MAGI1) is an intracellular adaptor protein that stabilizes epithelial junctions consistent with a tumor suppressive function in several cancers of epithelial origin. Here we report, based on experimental results and human breast cancer (BC) patients’ gene expression data, that MAGI1 is highly expressed and acts as tumor suppressor in estrogen receptor (ER)⁺/HER2⁻ but not in HER2⁺ or triple negative breast cancer (TNBC). Within the ER⁺/HER2⁻ subset, high MAGI1 expression associates with ESR1 and luminal genes GATA3 and FOXA1 expression and better prognosis, while low MAGI1 levels correlates with higher histological grade, more aggressive phenotype and worse prognosis. Experimentally, MAGI1 downregulation in the ER⁺ human BC cells MCF7 impairs ER expression and signaling, promotes cell proliferation, and reduces apoptosis and epithelial differentiation. MAGI1 downregulation in the ER⁺ murine BC cell line 67NR accelerates primary tumor growth and enhances experimental lung metastasis formation. MAGI1 expression is upregulated by estrogen/ER, downregulated by prostaglandin E2/COX-2axis, and negatively correlates with inflammation in ER⁺/HER2⁻ BC patients. Taken together, we show that MAGI1 is a new potential tumor suppressor in ER⁺/HER2⁻ breast cancer with possible prognostic value for the identification of patients at high-risk of relapse within this subset.

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.

Cluster miRNAs and cancer: Diagnostic, prognostic and therapeutic opportunities

MiRNAs are class of noncoding RNA important for gene expression regulation in many plants, animals and viruses. MiRNA clusters contain a set of two or more miRNA encoding genes, transcribed together as polycistronic miRNAs. Currently, there are approximately 159 miRNA clusters reported in the human genome consisting of miRNAs ranging from two or more miRNA genes. A large proportion of clustered miRNAs resides in and around the fragile sites or cancer associated genomic hotspots and plays an important role in carcinogenesis. Altered expression of miRNA cluster can be pro-tumorigenic or anti-tumorigenic and can be targeted for clinical management of cancer. Over the past few years, manipulation of miRNA clusters expression is attempted for experimental purpose as well as for diagnostic, prognostic and therapeutic applications in cancer. Re-expression of miRNAs by epigenetic therapy, genome editing such as clustered regulatory interspaced short palindromic repeats (CRISPR) and miRNA mowers showed promising results in cancer therapy. In this review, we focused on the potential of miRNA clusters as a biomarker for diagnosis, prognosis, targeted therapy as well as strategies for modulating their expression in a therapeutic context. This article is categorized under: Regulatory RNAs/RNAi/Riboswitches > Regulatory RNAs RNA Processing > Processing of Small RNAs RNA in Disease and Development > RNA in Disease Regulatory RNAs/RNAi/Riboswitches > Biogenesis of Effector Small RNAs.

Drug resistance and combating drug resistance in cancer

Cancer is the second leading cause of death in the US. Current major treatments for cancer management include surgery, cytotoxic chemotherapy, targeted therapy, radiation therapy, endocrine therapy and immunotherapy. Despite the endeavors and achievements made in treating cancers during the past decades, resistance to classical chemotherapeutic agents and/or novel targeted drugs continues to be a major problem in cancer therapies. Drug resistance, either existing before treatment (intrinsic) or generated after therapy (acquired), is responsible for most relapses of cancer, one of the major causes of death of the disease. Heterogeneity among patients and tumors, and the versatility of cancer to circumvent therapies make drug resistance more challenging to deal with. Better understanding the mechanisms of drug resistance is required to provide guidance to future cancer treatment and achieve better outcomes. In this review, intrinsic and acquired resistance will be discussed. In addition, new discoveries in mechanisms of drug resistance will be reviewed. Particularly, we will highlight roles of ATP in drug resistance by discussing recent findings of exceptionally high levels of intratumoral extracellular ATP as well as intracellular ATP internalized from extracellular environment. The complexity of drug resistance development suggests that combinational and personalized therapies, which should take ATP into consideration, might provide better strategies and improved efficacy for fighting drug resistance in cancer.

miR-25 Promotes Cell Proliferation, Migration, and Invasion of Non-Small-Cell Lung Cancer by Targeting the LATS2/YAP Signaling Pathway

Metastasis is the leading cause of high mortality in lung cancer patients, and metastatic lung cancer is difficult to treat. miRNAs are involved in various biological processes of cancer, including metastasis. Our previous studies revealed that miR-25 promoted non-small-cell lung cancer (NSCLC) cell proliferation and suppressed cell apoptosis by directly targeting TP53 and MOAP1. In this work, we further explored the miR-25 expression in NSCLC patients in the Cancer Genome Atlas (TCGA) database and measured the miR-25 expression levels in the tissues of NSCLC patients and cell lines. miR-25 was overexpressed in both NSCLC tissues and cell lines. NSCLC patients who expressed a higher level of miR-25 exhibited worse overall survival than those with a lower level of miR-25. Overexpression of miR-25 enhanced NSCLC cell migration and invasion, while the inhibition of miR-25 exhibited the opposite effects. We identified the large tumor suppressor homology 2 (LATS2) as a new target gene of miR-25 in lung cancer. The effects of miR-25 on promoting NSCLC cell migration and invasion were at least partially due to activation of the Hippo signaling pathway. Additionally, miR-25 antagomir inhibited xenograft tumor growth and metastasis by the upregulation of LATS2. Taken together, our findings demonstrate that miR-25 contribute to lung cancer cell proliferation and metastasis by targeting the LATS2/YAP signaling pathway, which implicate miR-25 as a promising therapeutic target for lung cancer metastasis. Given that oxidative stress induces the overexpression of miR-25 and plays a critical role in cancer progression, this study establishes miR-25 as an intermediate between oxidative stress and lung cancer metastasis.

Downregulation of SOX2 may be targeted by miR-590-5p and inhibits epithelial-to-mesenchymal transition in non-small-cell lung cancer

Non-small-cell lung cancer (NSCLC) is the leading type of cancer worldwide and sex determining region Y-box 2 (SOX2) has been implicated as an oncogene in various types of cancer. In the present study, SOX2 was positively associated with NSCLC stage and lymph node metastasis. Wound healing and Transwell assays demonstrated that knockdown of SOX2 inhibited A549 and H1299 cell migration. Furthermore, it was identified that knockdown of SOX2 inhibited epithelial-to-mesenchymal transition of NSCLC cells, which was demonstrated by increased expression of epithelial-cadherin and decreased expression of vimentin, zinc finger protein SNAI1 and zinc finger protein SNAI2. It was then demonstrated that SOX2 may be targeted by microRNA (miR)-590-5p, which indicated a potential therapeutic strategy for NSCLC focusing on the miR-590-5p/SOX2 axis.

The Roles of MicroRNA in Lung Cancer

Lung cancer is the most devastating malignancy in the world. Beyond genetic research, epigenomic studies—especially investigations of microRNAs—have grown rapidly in quantity and quality in the past decade. This has enriched our understanding about basic cancer biology and lit up the opportunities for potential therapeutic development. In this review, we summarize the involvement of microRNAs in lung cancer carcinogenesis and behavior, by illustrating the relationship to each cancer hallmark capability, and in addition, we briefly describe the clinical applications of microRNAs in lung cancer diagnosis and prognosis. Finally, we discuss the potential therapeutic use of microRNAs in lung cancer.

TRIM59 promotes gefitinib resistance in EGFR mutant lung adenocarcinoma cells

AIMS

The relationship between TRIM59 and drug resistance is elusive despite of its multiple uncovered roles in human cancers. Here we aimed to characterize the expression status of TRIM59 in gefitinib-resistant EGFR mutant lung adenocarcinoma cells and elucidate its mechanism underlying the drug resistance.

MAIN METHODS

Gefitinib-resistant cell lines were established by progressive dosage. Relative expression of TRIM59 was determined by both real-time PCR and Western blot. Target gene knockdown was achieved by specific shRNAs. Cell viability was measured by MTT assay. Cell apoptosis was analyzed by flow cytometry with Annexin V/7-AAD double staining. Cell proliferation was determined by clonogenic formation assay. Migration and invasion capacities were detected using transwell chamber assay. Direct interaction between TRIM59 and STAT3 was analyzed by co-immunoprecipitation assay.

KEY FINDINGS

We first observed overexpression of TRIM59 in gefitinib-resistant EGFR mutant lung adenocarcinoma cells. ShRNA-mediated knockdown of TRIM59 significantly inhibited cell viability and stimulated apoptosis. Meanwhile, TRIM59-deficiency suppressed cell migration and invasion. We further identified the interaction between TRIM59 and STAT3. TRIM59-deficiency remarkably impaired the activation of STAT3 signaling. STAT3-specific shRNAs significantly re-sensitized TRIM59-proficient EGFR mutant lung adenocarcinoma cells to gefitinib.

SIGNIFICANCE

Our data characterized aberrant TRIM59 overexpression in gefitinib-resistance EGFR mutant lung adenocarcinoma cells, and indicated the potential involvement of TRIM59-STAT3 signaling in the occurrence of gefitinib-resistance.

The role and mechanisms of action of microRNAs in cancer drug resistance

MicroRNAs (miRNAs) are small non-coding RNAs with a length of about 19–25 nt, which can regulate various target genes and are thus involved in the regulation of a variety of biological and pathological processes, including the formation and development of cancer. Drug resistance in cancer chemotherapy is one of the main obstacles to curing this malignant disease. Statistical data indicate that over 90% of the mortality of patients with cancer is related to drug resistance. Drug resistance of cancer chemotherapy can be caused by many mechanisms, such as decreased antitumor drug uptake, modified drug targets, altered cell cycle checkpoints, or increased DNA damage repair, among others. In recent years, many studies have shown that miRNAs are involved in the drug resistance of tumor cells by targeting drug-resistance-related genes or influencing genes related to cell proliferation, cell cycle, and apoptosis. A single miRNA often targets a number of genes, and its regulatory effect is tissue-specific. In this review, we emphasize the miRNAs that are involved in the regulation of drug resistance among different cancers and probe the mechanisms of the deregulated expression of miRNAs. The molecular targets of miRNAs and their underlying signaling pathways are also explored comprehensively. A holistic understanding of the functions of miRNAs in drug resistance will help us develop better strategies to regulate them efficiently and will finally pave the way toward better translation of miRNAs into clinics, developing them into a promising approach in cancer therapy.

MicroRNA-302c modulates peritoneal dialysis-associated fibrosis by targeting connective tissue growth factor

Long‐term peritoneal dialysis (PD) can lead to the induction of mesothelial/epithelial‐mesenchymal transition (MMT/EMT) and fibrosis; these effects eventually result in ultrafiltration failure and the discontinuation of PD. MicroRNA‐302c (miR‐302c) is believed to be involved in regulating tumour cell growth and metastasis by suppressing MMT, but the effect of miR‐302c on MMT in the context of PD is unknown. MiR‐302c levels were measured in mesothelial cells isolated from the PD effluents of continuous ambulatory peritoneal dialysis patients. After miR‐302c overexpression using lentivirus, human peritoneal mesothelial cell line (HMrSV5) and PD mouse peritoneum were treated with TGF‐β1 or high glucose peritoneal dialysate respectively. MiR‐302c expression level and MMT‐related factors alteration were observed. In addition, fibrosis of PD mouse peritoneum was alleviated by miR‐302c overexpression. Furthermore, the expression of connective tissue growth factor (CTGF) was negatively related by miR‐302c, and LV‐miR‐302c reversed the up‐regulation of CTGF induced by TGF‐β1. These data suggest that there is a novel TGF‐β1/miR‐302c/CTGF pathway that plays a significant role in the process of MMT and fibrosis during PD. MiR‐302c might be a potential biomarker for peritoneal fibrosis and a novel therapeutic target for protection against peritoneal fibrosis in PD patients.