miR-497 may enhance the sensitivity of non-small cell lung cancer cells to gefitinib through targeting the insulin-like growth factor-1 receptor

Unraveling the Post-Translational Modifications and therapeutical approach in NSCLC pathogenesis

Non-Small Cell Lung Cancer (NSCLC) is the most prevalent kind of lung cancer with around 85% of total lung cancer cases. Despite vast therapies being available, the survival rate is low (5 year survival rate is 15%) making it essential to comprehend the mechanism for NSCLC cell survival and progression. The plethora of evidences suggests that the Post Translational Modification (PTM) such as phosphorylation, methylation, acetylation, glycosylation, ubiquitination and SUMOylation are involved in various types of cancer progression and metastasis including NSCLC. Indeed, an in-depth understanding of PTM associated with NSCLC biology will provide novel therapeutic targets and insight into the current sophisticated therapeutic paradigm. Herein, we reviewed the key PTMs, epigenetic modulation, PTMs crosstalk along with proteogenomics to analyze PTMs in NSCLC and also, highlighted how epi‑miRNA, miRNA and PTM inhibitors are key modulators and serve as promising therapeutics.

Monitoring EGFR-lung cancer evolution: a possible beginning of a "methylation era" in TKI resistance prediction

The advances in scientific knowledge on biological therapies of the last two decades have impressively oriented the clinical management of non-small-cell lung cancer (NSCLC) patients. The treatment with tyrosine kinase inhibitors (TKIs) in patients harboring Epidermal Growth Factor Receptor (EGFR)-activating mutations is dramatically associated with an improvement in disease control. Anyhow, the prognosis for this selected group of patients remains unfavorable, due to the innate and/or acquired resistance to biological therapies. The methylome analysis of many tumors revealed multiple patterns of methylation at single/multiple cytosine-phosphate-guanine (CpG) sites that are linked to the modulation of several cellular pathways involved in cancer onset and progression. In lung cancer patients, ever increasing evidences also suggest that the association between DNA methylation changes at promoter/intergenic regions and the consequent alteration of gene-expression signatures could be related to the acquisition of resistance to biological therapies. Despite this intriguing hypothesis, large confirmatory studies are demanded to consolidate and finalize many preliminary observations made in this field. In this review, we will summarize the available knowledge about the dynamic role of DNA methylation in EGFR-mutated NSCLC patients.

microRNA-497 prevents pancreatic cancer stem cell gemcitabine resistance, migration, and invasion by directly targeting nuclear factor kappa B 1

Objectives: Cancer stem cells (CSCs) comprise a small population of cells in cancerous tumors and play a critical role in tumor resistance to chemotherapy. miRNAs have been reported to enhance the sensitivity of pancreatic cancer to chemotherapy. However, the underlying molecular mechanism requires better understanding.

Methods: Cell viability and proliferation were examined with CCK8 assays. Quantitative real-time polymerase chain reaction was executed to assess mRNA expression. StarBase database was used to select the target genes of miRNA, which were further affirmed by dual luciferase assay. Transwell assay was used to analyze cell invasion and migration.

Results: We proved that miR-497 could be obviously downregulated in pancreatic cancer tissues and CSCs from Aspc-1 and Bxpc-3 cells. In addition, inhibition of miR-497 evidently accelerated pancreatic CSC gemcitabine resistance, migration and invasion. Moreover, we revealed that nuclear factor kappa B 1 (NFκB1) was prominently upregulated in pancreatic cancer tissues and pancreatic CSCs, and NFκB1 was also identified as a direct target of miR-497. Furthermore, we demonstrated that overexpression of NFκB1 could also notably promote the viability, migration, and invasion of gemcitabine-treated pancreatic CSCs, but this effect could be partially abolished by miR-497 overexpression.

Conclusions: Those findings suggest that miR-497 overexpression could suppress gemcitabine resistance and the metastasis of pancreatic CSCs and non-CSCs by directly targeting NFκB1.

Different roles of the insulin-like growth factor (IGF) axis in non-small cell lung cancer

Abstract:

Non-small cell lung cancer (NSCLC) remains one of the deadliest malignant diseases, with high incidence and mortality worldwide. The insulin-like growth factor (IGF) axis, consisting of IGF-1, IGF-2, related receptors (IGF-1R, -2R), and high-affinity binding proteins (IGFBP 1–6), is associated with promoting fetal development, tissue growth, and metabolism. Emerging studies have also identified the role of the IGF axis in NSCLC, including cancer growth, invasion, and metastasis. Upregulation of IGE-1 and IGF-2, overexpression of IGF-1R, and dysregulation of downstream signaling molecules involved in the PI-3K/Akt and MAPK pathways jointly increase the risk of cancer growth and migration in NSCLC. At the genetic level, some noncoding RNAs could influence the proliferation and differentiation of tumor cells through the IGF signaling pathway. The resistance to some promising drugs might be partially attributed to the IGF axis. Therapeutic strategies targeting the IGF axis have been evaluated, and some have shown promising efficacy. In this review, we summarize the biological roles of the IGF axis in NSCLC, including the expression and prognostic significance of the related components, noncoding RNA regulation, involvement in drug resistance, and therapeutic application. This review offers comprehensive understanding of NSCLC and provides insightful ideas for future research.

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.

miR-497 inhibits proliferation and invasion in triple-negative breast cancer cells via YAP1

MicroRNA (miR)-497 has been reported as a tumor suppressor in various cancer types. Nonetheless, the regulation of triple-negative breast cancer (TNBC) by miR-497 remains poorly understood. The present study aimed to investigate the potential function and mechanism of miR-497 in TNBC. A total of 36 TNBC and matched non-cancerous tissue samples were collected for analysis. Reverse transcription-quantitative PCR was performed to detect the miR-497 levels in TNBC tissue. The association between miR-497 expression, clinical characteristics and survival was then analyzed. To investigate the role of miR-497 in TNBC, MTT, colony formation, Transwell invasion, cell cycle and cell apoptosis assays were conducted following transfection of miR-497 mimics into the MDA-MB-231 and MDA-MB-468 cell lines. Luciferase reporter assays and western blot analysis were used to confirm the regulation of a putative target of miR-497. The results indicated that the expression of miR-497 was downregulated in the TNBC specimens. Further analysis demonstrated that the expression of miR-497 was downregulated in patients with advanced TNBC stages and that low miR-497 was associated with poor prognosis in patients with TNBC. Transfection of miR-497 mimics inhibited TNBC cell proliferation and increased cell apoptosis in MDA-MB-231 and MDA-MB-468 cells. Moreover, cell migration was inhibited following overexpression of miR-497, which also led to the arrest of the breast cancer cells in the G₀/G₁ phase of the cell cycle. Yes-associated protein 1 (YAP1), a critical molecule in the Hippo pathway, was identified as a target of miR-497. Notably, the protein and mRNA expression levels of YAP1 in MDA-MB-231 and MDA-MB-468 cells were downregulated following overexpression of miR-497. Overall, the findings of the present study indicated that miR-497 inhibited TNBC cell proliferation and migration and induced cell apoptosis by negatively regulating YAP1 expression. Thus, targeting miR-497 may represent a potential strategy for the treatment of TNBC.

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.

MicroRNA-497 functions as an inflammatory suppressor via targeting DDX3Y and modulating toll-like receptor 4/NF-κB in cigarette smoke extract-stimulated human bronchial epithelial cells

BACKGROUND

We aimed to investigate the biological effect of miR-497 in cigarette smoke extract (CSE)-damaged human bronchial epithelial (HBE) cells and the underlying molecular mechanism.

METHODS

MiR-497 mimic was transfected into HBE cells to up-regulate miR-497 expression. Cigarette smoke extract (CSE, 20 μg/mL) was utilized to treat HBE cells to form the injury model. Cell proliferation and apoptosis were detected by CCK8 and flow cytometry assays. DDX3Y mRNA expression was determined by a quantitative reverse transcriptase-polymerase chain reaction. The interaction between miR-497 and DDX3Y was verified by a luciferase reporter assay. Protein expression levels were tested by western blotting.

RESULTS

CSE treatment decreased miR-497 level in HBE cells. CSE exposure restrained cell proliferation, promoted cell apoptosis and enhanced the relative expression of TLR4 and p-NF-κB p65. DDX3Y was predicted as a target of miR-497. The mRNA and protein expression of DDX3Y was negatively modulated by miR-497 in CSE-injured HBE cells. Up-regulation of miR-497 by miR-497 mimic increased cell proliferation and reduced cell apoptosis in CSE-treated HBE cells, which were rescued by DDX3Y high expression in CSE-treated HBE cells. Consistently, Bcl-2 protein level was heightened, whereas Bax and actived caspase-3/9 protein levels were decreased by miR-497 mimic in CSE-stimulated HBE cells, which was reversed by DDX3Y over-expression in CSE-stimulated HBE cells. The relative expression of TLR4 and p-NF-κB p65 was decreased by miR-497 mimic, whereas they were rescued by DDX3Y over-expression in CSE-damaged HBE cells.

CONCLUSIONS

The results of the present study demonstrate that up-regulation of miR-497 exhibits a protective effect on CSE-damaged HBE cells, which might be achieved by targeting DDX3Y and regulating the TLR4/NF-κB pathway.

miR-762 activation confers acquired resistance to gefitinib in non-small cell lung cancer

Background

Epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs) (e.g. gefitinib) currently remain the first-line treatment for patients with advanced non-small-cell lung cancer (NSCLC) with activating EGFR mutation. However, acquired resistance to gefitinib, which occurs frequently through unidentified mechanisms, significantly attenuate therapeutic effectiveness. Previous miRNA microarray analysis reveals that expression levels of a conserved oncomiR miR-762 are significantly upregulated in gefitinib-resistant NSCLC cells. We therefore aim to elucidate the role and underlying mechanisms of miR-762 during the pathogenesis of gefitinib resistance.

Methods

miR-762 expression in gefitinib-resistant NSCLC tissues and cells was evaluated using RT-qPCR. The potential regulation of miR-762 expression by IL-6 was studied using pharmacological and biochemical approaches. Effects of miR-762 manipulation on sensitivity to gefitinib was assessed using MTT, apoptotic ELISA and xenograft model. Finally, the posttranscriptional regulation of active BCR related protein (ABR) by miR-762 was determined using luciferase assay and site-directed mutagenesis.

Results

miR-762 expression was upregulated in gefitinib-resistant NSCLC tissues and cells, and this upregulation predicted a poor post-chemotherapy prognosis in NSCLC patients. miR-762 upregulation, induced by IL-6 signaling, significantly enhanced cell survival and rendered NSCLC cells unresponsiveness to gefitinib-elicited cell death. We finally provided the evidence that the oncogenic effect of miR-762 was mediated mainly through posttranscriptional repression of ABR in gefitinib-resistant NSCLC cells.

Conclusions

Our findings provide a rationale for future efforts testing miR-762 inhibition and ABR restoration co-treatment in patients with recurrent EGFR mutant NSCLC to therapeutically combat the heterogeneity of EGFR-TKIs resistance mechanisms.

MicroRNA-625 inhibits the progression of non‑small cell lung cancer by directly targeting HOXB5 and deactivating the Wnt/β-catenin pathway

Numerous microRNAs (miRs) are dysregulated in non‑small cell lung cancer (NSCLC), serving pivotal roles in its formation and progression. miR‑625 is dysregulated in several types of human cancer, but its involvement in the formation and development of NSCLC remains poorly understood. In the present study, we aimed to investigate miR‑625 expression in NSCLC and its role in regulating NSCLC cell behavior. miR‑625 expression in NSCLC tissues and cell lines was detected using reverse transcription‑quantitative polymerase chain reaction. The effects of miR‑625 overexpression on NSCLC cell proliferation, apoptosis, migration and invasion in vitro were assessed using an MTT assay, flow cytometry, and cell migration and invasion assays, respectively. The effects of miR‑625 upregulation on NSCLC growth were evaluated in an in vivo xenograft model. The molecular mechanisms underlying the tumor‑suppressing roles of miR‑625 in NSCLC were explored in detail. miR‑625 expression was determined to be downregulated in NSCLC tissues and cell lines. This decreased expression was associated with advanced clinical features and poor overall survival of patients with NSCLC. Exogenous miR‑625 expression suppressed NSCLC cell proliferation, migration and invasion, and induced apoptosis in vitro. miR‑625 upregulation hindered NSCLC tumor growth in vivo. Homeobox B5 (HOXB5) was proposed to be the direct target gene of miR‑625 in NSCLC cells. The tumor‑suppressing effects of HOXB5 silencing were similar to those of miR‑625 overexpression in NSCLC cells. In rescue experiments, HOXB5 overexpression partially reversed the inhibitory effects of miR‑625 in NSCLC cells. miR‑625 upregulation directly targeted HOXB5 to deactivate the Wnt/β‑catenin signaling pathway in NSCLC cells in vitro and in vivo. miR‑625 was determined to be associated with HOXB5 suppression and Wnt/β‑catenin pathway deactivation, which in turn inhibited the aggressive behavior of NSCLC cells in vitro and in vivo.

Expression of miR-486-5p and its significance in lung squamous cell carcinoma

Lung squamous cell carcinoma (LUSC) is one of the main histological types of lung cancer with high mortality. The role of microRNA-486-5p in LUSC remains unclear. In the current study, the aim was to explore miR-486-5p expression and its role in LUSC. The miR-486-5p expression was significantly low-expressed in patients with LUSC from The Cancer Genome Atlas database, which was further confirmed in the Gene Expression Omnibus database, patients' tissues, different cell lines by quantitative real-time polymerase chain reaction, and the high-throughput gene sequencing data of lung tissues of mice after a long-term B(a)P exposure. The meta-analysis was performed to evaluate the expression and diagnosis power of miR-486-5p (standard mean difference = -2.25; 95% confidence interval: -3.47 to -1.03; P = 0.0003; area under curve = 0.9082). Functional enrichment analysis revealed the potential function of miR-486-5p in LUSC using gene set enrichment analysis and clusterProfiler package in R software. At last, the hub genes (PTEN, TEK, PIK3R1, PPM1B, SMAD2, and SPTA1) of miR-486-5p were verified. In conclusion, miR-486-5p may be a LUSC antioncogene, playing an important role to serve as a biomarker in LUSC.