Knockdown of microRNA-1323 restores sensitivity to radiation by suppression of PRKDC activity in radiation-resistant lung cancer cells

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.

The Molecular and Cellular Strategies of Glioblastoma and Non-Small-Cell Lung Cancer Cells Conferring Radioresistance

Ionizing radiation (IR) has been shown to play a crucial role in the treatment of glioblastoma (GBM; grade IV) and non-small-cell lung cancer (NSCLC). Nevertheless, recent studies have indicated that radiotherapy can offer only palliation owing to the radioresistance of GBM and NSCLC. Therefore, delineating the major radioresistance mechanisms may provide novel therapeutic approaches to sensitize these diseases to IR and improve patient outcomes. This review provides insights into the molecular and cellular mechanisms underlying GBM and NSCLC radioresistance, where it sheds light on the role played by cancer stem cells (CSCs), as well as discusses comprehensively how the cellular dormancy/non-proliferating state and polyploidy impact on their survival and relapse post-IR exposure.

Long non-coding RNA ZNFX1 antisense 1 (ZFAS1) suppresses anti-oxidative stress in chondrocytes during osteoarthritis by sponging microRNA-1323

LncRNAs play a regulatory role in osteoarthritis (OA); however, the detailed mechanism remains to be elucidated. This study aimed to investigate the role of lncRNA zinc finger NFX1-type containing 1 (ZNFX1) antisense 1 (ZFAS1) in OA progression and explore its possible mechanismsagainst oxidative stress. Human cartilage specimens were obtained from 10 patients without OA who underwent traumatic amputation and 25 patients with OA who underwent total knee replacement surgery. Chondrocytes were prepared from harvested articular cartilage. ZFAS1, nuclear factor erythroid 2-related factor 2 (Nrf2), and heme oxygenase 1 (HO-1) expression levels were analyzed using quantitative reverse transcription PCR and WB. The chondrocyte growth was indicated by MTT and colony formation assays. Chondrocyte apoptosis, reactive oxygen species generation, and anti-oxidative enzymes activities were also measured. ZFAS1 expression was reduced in OA samples and lipopolysaccharide (LPS)-treated chondrocytes used as an OA cell model mimic. ZFAS1 overexpression facilitated proliferation and repressed oxidative stress, inflammation, and apoptosis in LPS-induced chondrocytes. ZFAS1 also activated the anti-oxidative Nrf2-HO-1 pathway. ZFAS1 directly targeted miR-1323, which partially reversed the effects of ZFAS1 on chondrocyte proliferation, oxidative stress, inflammation, and apoptosis. Furthermore, Nrf2 was negatively regulated by miR-1323. The effect of miR-1323 inhibition was partly abrogated by the administration of brusatol, an Nrf2 inhibitor. Collectively, the results showed that ZFAS1 promoted chondrocyte proliferation and repressed oxidative stress, possibly by regulating the novel miR-1323-Nrf2 axis of the inflammation and apoptosis triggered by LPS, indicating that ZFAS1 is a promising therapeutic target for OA.

Circ_0030998 Restrains Cisplatin Resistance Through Mediating miR-1323/PDCD4 Axis in Non-small Cell Lung Cancer

We aimed to explore the underlying mechanism behind the cisplatin (DDP) resistance of non-small cell lung cancer (NSCLC) cells to identify novel potential therapeutic targets to overcome chemoresistance. Real-time quantitative polymerase chain reaction (RT-qPCR) and Western blot assay were applied to analyze RNA and protein expression, respectively. Cell Counting Kit-8 (CCK8) assay was conducted to analyze the DDP resistance of NSCLC cells. Colony formation assay and 5-Ethynyl-2'-deoxyuridine (EdU) assay were performed to analyze cell proliferation ability. Flow cytometry was applied to assess cell apoptosis. Cell migration and invasion were assessed by transwell assays. Cell glycolytic metabolism was analyzed using commercial kits. Dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay were performed to test the intermolecular target relations. Circular RNA_0030998 (circ_0030998) was down-regulated in DDP-resistant NSCLC tissues and cell lines. Circ_0030998 overexpression restrained the DDP resistance, proliferation, migration, invasion and glycolytic metabolism and triggered the apoptosis of NSCLC cells. Circ_0030998 overexpression contributed to the anti-tumor effect of DDP in the growth of xenograft tumor in vivo. MicroRNA-1323 (miR-1323) was a molecular target of circ_0030998 in NSCLC cells. Circ_0030998 overexpression-mediated effects on the DDP resistance and malignant properties of NSCLC cells were largely based on its negative regulation of miR-1323. MiR-1323 interacted with programmed cell death 4 (PDCD4). Circ_0030998 positively regulated PDCD4 expression partly through sponging miR-1323. MiR-1323 silencing restrained DDP resistance and progression of NSCLC partly through up-regulating PDCD4. Circ_0030998 suppressed DDP resistance and NSCLC progression depending on the regulation of miR-1323/PDCD4 axis.

Exosome-Mediated Transfer of miR-1323 from Cancer-Associated Fibroblasts Confers Radioresistance of C33A Cells by Targeting PABPN1 and Activating Wnt/β-Catenin Signaling Pathway in Cervical Cancer

Plenty of pieces of evidence suggest that the resistance to radiotherapy greatly influences the therapeutic effect in cervical cancer (CCa). MicroRNAs (miRNAs) have been reported to regulate cellular processes by acting as tumor suppressors or promoters, thereby driving radioresistance or radiosensitivity. Meanwhile, it has been reported that microRNA-1323 (miR-1323) widely participates in cancer progression and radiotherapy effects. However, the role of miR-1323 is still not clear in CCa. Hence, in this study, we are going to investigate the molecular mechanism of miR-1323 in CCa cells. In the beginning, miR-1323 was found aberrantly upregulated in CCa cells via RT-qPCR assay. Functional assays indicated that miR-1323 was transferred by cancer-associated fibroblasts-secreted (CAFs-secreted) exosomes and miR-1323 downregulation suppressed cell proliferation, migration, invasion, and increased cell radiosensitivity in CCa. Mechanism assays demonstrated that miR-1323 targeted poly(A)-binding protein nuclear 1 (PABPN1). Besides, PABPN1 recruited insulin-like growth factor 2 mRNA binding protein 1 (IGF2BP1) to regulate glycogen synthase kinase 3 beta (GSK-3β) and influenced Wnt/β-catenin signaling pathway. Therefore, rescue experiments were implemented to validate that PABPN1 overexpression rescued the inhibited cancer development and radioresistance induced by the miR-1323 inhibitor. In conclusion, miR-1323 was involved in CCa progression and radioresistance which might provide a novel insight for CCa treatment.

Interactions between miRNAs and Double-Strand Breaks DNA Repair Genes, Pursuing a Fine-Tuning of Repair

The repair of DNA damage is a crucial process for the correct maintenance of genetic information, thus, allowing the proper functioning of cells. Among the different types of lesions occurring in DNA, double-strand breaks (DSBs) are considered the most harmful type of lesion, which can result in significant loss of genetic information, leading to diseases, such as cancer. DSB repair occurs through two main mechanisms, called non-homologous end joining (NHEJ) and homologous recombination repair (HRR). There is evidence showing that miRNAs play an important role in the regulation of genes acting in NHEJ and HRR mechanisms, either through direct complementary binding to mRNA targets, thus, repressing translation, or by targeting other genes involved in the transcription and activity of DSB repair genes. Therefore, alteration of miRNA expression has an impact on the ability of cells to repair DSBs, which, in turn, affects cancer therapy sensitivity. This latter gives account of the importance of miRNAs as regulators of NHEJ and HRR and places them as a promising target to improve cancer therapy. Here, we review recent reports demonstrating an association between miRNAs and genes involved in NHEJ and HRR. We employed the Web of Science search query TS (“gene official symbol/gene aliases*” AND “miRNA/microRNA/miR-”) and focused on articles published in the last decade, between 2010 and 2021. We also performed a data analysis to represent miRNA–mRNA validated interactions from TarBase v.8, in order to offer an updated overview about the role of miRNAs as regulators of DSB repair.

miR-20b and miR-125a promote tumorigenesis in radioresistant esophageal carcinoma cells

Radiation therapy is an effective method in the management of esophageal cancer. MicroRNAs (miRNAs) have been reported to play an important role in tumorigenesis. However, the roles of specific miRNAs in radioresistant esophageal cancer remain to be investigated. In present study, the relative expression level of miR-20b-5p and miR-125a-5p were evaluated by quantitative Real-time polymerase chain reaction. Cell counting Kit-8 assay, wound-healing assay, transwell assay were used to assess cell proliferation, cell migration and cell invasion. TUNEL and Annexin V-FITC assays were applied to evaluate cell apoptosis. Dual-luciferase reporter gene assay was conducted to identify direct targets of miRNAs. The protein expression level was assessed by Western blot. The results indicated that miR-20b-5p was increased in radioresistant KYSE-150R cells compared with KYSE-150 cells, whereas miR-125a-5p was downregulated. MiR-20b-5p upregulation promoted cell proliferation, migration, invasion, and the EMT process, and decreased apoptosis by negatively regulating PTEN. MiR-125a-5p inhibited cell proliferation, migration, invasion, the EMT process and it induced apoptosis by negatively regulating IL6R. These data indicate that miR-20b-5p and miR-125a-5p promote tumorigenesis in radioresistant KYSE-150R cells and have the potential to be used as novel therapeutic targets for the treatment of esophageal cancer.

MicroRNA-1323 downregulation promotes migration and invasion of breast cancer cells by targeting tumour protein D52

Breast cancer (BC) is one of the most common malignancies globally in women, with high mortality rate as a result of tumour metastasis. MicroRNAs play vital roles in the occurrence and development of human cancer. This study aimed to investigate the biological roles of miR-1323 in BC. The expression levels of miR-1323 were detected by quantitative real-time PCR assay. The effect of miR-1323 on BC cell proliferation was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and colony formation assay. Wound healing analysis and Matrigel Transwell assay were conducted to evaluate miR-1323-mediated BC cell migration and invasion. A luciferase reporter assay was used to test the target of miR-1323. We found that miR-1323 levels were downregulated in BC tissues and serums. Low-miR-1323 levels were associated with lymph node metastasis and advanced clinical stage. Tumour protein D52 (TPD52) was identified as a direct target of miR-1323. Low expression of miR-1323 contributed to the overexpression of TPD52 leading to enhanced BC progression. Our findings suggest that silencing of miR-1323 enhances BC development by regulating TPD52 expression, suggesting that miR-1323 and TPD52 may serve as potential therapeutic targets for BC treatment.

Emerging role of non-coding RNAs in response of cancer cells to radiotherapy

Radiotherapy is an effective method for treatment of a large proportion of human cancers. Yet, the efficacy of this method is precluded by the induction of radioresistance in tumor cells and the radiation-associated injury of normal cells surrounding the field of radiation. These restrictions necessitate the introduction of modalities for either radiosensitization of cancer cells or protection of normal cells against adverse effects of radiation. Non-coding RNAs (ncRNAs) have essential roles in the determination of radiosensitivity. Moreover, ncRNAs can modulate radiation-induced side effects in normal cells. Several microRNAs (miRNAs) such as miR-620, miR-21 and miR-96-5p confer radioresistance, while other miRNAs including miR-340/ 429 confer radiosensitivity. The expression levels of a number of miRNAs are associated with radiation-induced complications such as lung fibrosis or oral mucositis. The expression patterns of several long non-coding RNAs (lncRNAs) such as MALAT1, LINC00630, HOTAIR, UCA1 and TINCR are associated with response to radiotherapy. Taken together, lncRNAs and miRNAs contribute both in modulation of response of cancer cells to radiotherapy and in protection of normal cells from the associated side effects. The current review provides an overview of the roles of these transcripts in these aspects.

Circular RNA_LARP4 Sponges miR-1323 and Hampers Progression of Esophageal Squamous Cell Carcinoma Through Modulating PTEN/PI3K/AKT Pathway

BACKGROUND

Emerged as important regulators in cancer progression, circular RNAs have been tested to participate in diverse biological processes. Former studies have suggested that circular RNA_LARP4 (circLARP4) exerts indispensable function on the development of different cancers such as gastric cancer and ovarian cancer. Nonetheless, the specific role of circLARP4 has not been discovered in ESCC.

AIMS

The aim of this study is to explore the biological function and regulatory mechanism of circLARP4 in ESCC.

METHODS

CircLARP4, miR-1323, and PTEN expression levels were quantified by RT-qPCR. CCK-8, EdU, caspase-3 activity, wound healing, transwell, and western blot assays were chosen to assess ESCC cell growth. Luciferase reporter, RIP, and RNA pull-down assays were performed to examine the interaction between miR-1323 and circLARP4 (or PTEN).

RESULTS

CircLARP4 expression was observably downregulated in ESCC cell lines, and overexpressed circLARP4 restrained cell proliferation and migration whereas boosted cell apoptosis in ESCC. Molecular mechanism experiments revealed that circLARP4 could act as a sponge for miR-1323 and negatively modulated miR-1323 expression in ESCC. Interestingly, the repression of miR-1323 was correlated with inhibitive cell proliferation, migration, and promotive apoptosis. Besides, miR-1323 bound with PTEN, and PTEN expression was negatively regulated by miR-1323 whereas positively regulated by circLARP4 in ESCC. Moreover, rescue assays testified that miR-1323 overexpression or PTEN deficiency could countervail the function of circLARP4 overexpression on ESCC progression. More importantly, circLARP4 played an inhibitory role in PI3K/AKT pathway.

CONCLUSIONS

CircLARP4 sponges miR-1323 and hampers tumorigenesis of ESCC through modulating PTEN/PI3K/AKT pathway.

miR-1323 Promotes Cell Migration in Lung Adenocarcinoma by Targeting Cbl-b and Is an Early Prognostic Biomarker

Purpose: MicroRNAs are known to regulate cellular processes in non-small cell lung cancer (NSCLC) cells and predict prognosis. However, identification of specific microRNAs in NSCLC as potential therapeutic targets is controversial. We aim to determine the clinical significance of miR-1323 in the prognosis of patients with lung cancer and the potential mechanism. Patients and methods: A bioinformatics approach was used to screen the importance microRNA in NSCLC through the online GEO database (GSE42425). The relationship between expression level of miR-1323 and overall survival of lung cancer patients was analyzed. Additionally, an independent corhort including 53 NSCLC cases that underwent resection validated the connection between miR-1323 and LUAD patients' overall survival. Next, the function of miR-1323 was studied in vitro by transient transfection. A more in-depth mechanism was studied through luciferase reporter gene experiments. Results: High miR-1323 expression correlated with poor survival in NSCLC patients (P = 0.011), and in lung adenocarcinoma (LUAD) patients (P = 0.015) based on GEO database (GSE42425). In the independent cohort based on our hospital, high miR-1323 expression was associated with LUAD patients (P = 0.025). Moreover, transfection with mimics of miR-1323 showed an increased migratory capacity in LUAD A549 and HCC827 cells. In addition, E3 ubiquitin-protein ligase Casitas B-lineage Lymphoma-b (Cbl-b) was found to be the target genes of miR-1323 and significantly down regulated after mimics of miR-1323 transfection, and high Cbl-b expression predicted better prognosis in NSCLC and LUAD (P = 0.00072 and P = 0.02, respectively). Conclusion: The miR-1323 promoted LUAD migration through inhibiting Cbl-b expression. High miR-1323 expression predicted poor prognosis in LUAD patients.

The characteristics of lung cancer in Xuanwei County: A review of differentially expressed genes and noncoding RNAs on cell proliferation and migration

The occurrence of lung cancers is the highest in Xuanwei County, Yunnan province, China, especially among nonsmoking women. Domestic combustion of smoky coal induces serious indoor air pollution and is considered to be the main cause of human lung cancers. The occurrence of lung cancer in Xuanwei County has unique characteristics, such as the high morbidity in nonsmoking women or people with no family history. In the present review, we summarize advances in identification of differentially expressed genes, regulatory lncRNAs and miRNAs in cell proliferation and migration of lung cancers in Xuanwei County. Moreover, several regulatory differentially expressed genes (DEGs) or noncoding RNAs have diagnostic and prognostic significance for lung cancers in Xuanwei County and have the potential to serve as biomarkers.

HNRNPA2/B1 is upregulated in endocrine-resistant LCC9 breast cancer cells and alters the miRNA transcriptome when overexpressed in MCF-7 cells

MicroRNAs are dysregulated in breast cancer. Heterogeneous Nuclear Ribonucleoprotein A2/B1 (HNRNPA2/B1) is a reader of the N(6)-methyladenosine (m6A) mark in primary-miRNAs (pri-miRNAs) and promotes DROSHA processing to precursor-miRNAs (pre-miRNAs). We examined the expression of writers, readers, and erasers of m6A and report that HNRNPA2/B1 expression is higher in tamoxifen-resistant LCC9 breast cancer cells as compared to parental, tamoxifen-sensitive MCF-7 cells. To examine how increased expression of HNRNPA2/B1 affects miRNA expression, HNRNPA2/B1 was transiently overexpressed (~5.4-fold) in MCF-7 cells for whole genome miRNA profiling (miRNA-seq). 148 and 88 miRNAs were up- and down-regulated, respectively, 48 h after transfection and 177 and 172 up- and down-regulated, respectively, 72 h after transfection. MetaCore Enrichment analysis identified progesterone receptor action and transforming growth factor β (TGFβ) signaling via miRNA in breast cancer as pathways downstream of the upregulated miRNAs and TGFβ signaling via SMADs and Notch signaling as pathways of the downregulated miRNAs. GO biological processes for mRNA targets of HNRNPA2/B1-regulated miRNAs included response to estradiol and cell-substrate adhesion. qPCR confirmed HNRNPA2B1 downregulation of miR-29a-3p, miR-29b-3p, and miR-222 and upregulation of miR-1266-5p, miR-1268a, miR-671-3p. Transient overexpression of HNRNPA2/B1 reduced MCF-7 sensitivity to 4-hydroxytamoxifen and fulvestrant, suggesting a role for HNRNPA2/B1 in endocrine-resistance.

LncRNA GAS5-mediated miR-1323 promotes tumor progression by targeting TP53INP1 in hepatocellular carcinoma

Background: MiR-1323 was identified in 2006. Until now, the roles and mechanisms of miR-1323 in the progression of cancers including hepatocellular carcinoma (HCC) remain unknown. The aim of this study was to investigate the expressions, roles and mechanisms of miR-1323 in HCC development.

Methods: QRT-PCR was used to evaluate the expressions of miR-1323, GAS5 and TP53INP1 in HCC tissues and cell lines. CCK-8 assay, transwell invasion assay and flow cytometry assay were conducted to evaluate the proliferation, invasion and apoptosis of HCC cells. Luciferase assay was used to identify microRNA-target interaction.

Results: Firstly, our results showed that miR-1323 promoted proliferation and invasion, and inhibited apoptosis of HCC cells. Secondly, we found that TP53INP1 was a direct target of miR-1323 and could reverse the effects of miR-1323 on proliferation, invasion and apoptosis of HCC cells. Thirdly, our results showed that long non-coding RNA (lncRNA) GAS5 and miR-1323 could interact with each other and affect biological processes of HCC cells. Furthermore, we identified the negative correlations between miR-1323 and TP53INP1, and between miR-1323 and GAS5 in tumor tissues of patients with HCC.

Conclusion: Taken together, our study revealed the important roles of GAS5/miR-1323/TP53INP1 axis in HCC progression. This study also provided promising strategies for targeted therapy of patients with HCC.

Tissue-specific and exosomal miRNAs in lung cancer radiotherapy: from regulatory mechanisms to clinical implications

Lung cancer is the most prevalent and deadly malignancy. Radiotherapy is a major treatment modality for lung cancer. Nevertheless, radioresistance poses a daunting challenge that largely limits the efficacy of radiotherapy. There is a pressing need for deciphering molecular mechanisms underlying radioresistance and elucidating novel therapeutic targets for individualized radiotherapy. MicroRNAs are categorized as small noncoding RNAs that modulate target-gene expression posttranscriptionally and are implicated in carcinogenesis and cancer resistance to treatment. Overwhelming evidence has unraveled that tissue-specific miRNAs are essential for regulation of the radiosensitivity in lung cancer cells through a complex interaction with multiple biological processes and radiation-induced pathways. Moreover, exosome-derived miRNAs are a novel horizon in lung cancer treatment in which exosomal miRNAs act as potential diagnostic and therapeutic biomarkers of radiotherapy. In the present review, we discuss the mediation of key biological processes and signaling pathways by tissue-specific miRNAs in lung cancer radiotherapy. Additionally, we provide new insight into the potential significance of exosomal miRNAs in radiation response. Lastly, we highlight miRNAs as promising predictors and therapeutic targets to tailor personalized lung cancer radiotherapy.

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.

MicroRNA in lung cancer: role, mechanisms, pathways and therapeutic relevance

Lung cancer is the cardinal cause of cancer-related deaths with restricted recourse of therapy throughout the world. Clinical success of therapies is not very promising due to - late diagnosis, limited therapeutic tools, relapse and the development of drug resistance. Recently, small ∼20-24 nucleotides molecules called microRNAs (miRNAs) have come into the limelight as they play outstanding role in the process of tumorigenesis by regulating cell cycle, metastasis, angiogenesis, metabolism and apoptosis. miRNAs essentially regulate gene expression via post-transcriptional regulation of mRNA. Nevertheless, few studies have conceded the role of miRNAs in activation of gene expression. A large body of data generated by numerous studies is suggestive of their tumor-suppressing, oncogenic, diagnostic and prognostic biomarker roles in lung cancer. They have also been implicated in regulating cancer cell metabolism and resistance or sensitivity towards chemotherapy and radiotherapy. Further, miRNAs have also been convoluted in regulation of immune checkpoints - Programmed death 1 (PD-1) and its ligand (PD-L1). These molecules play a significant role in tumor immune escape leading to the generation of a microenvironment favouring tumor growth and progression. Therefore, it is imperative to explore the expression of miRNA and understand its relevance in lung cancer and development of anti-cancer strategies (anti - miRs, miR mimics and micro RNA sponges). In view of the above, the role of miRNA in lung cancer has been dissected and the associated mechanisms and pathways are discussed in this review.

Radiosensitizing effects of miR-18a-5p on lung cancer stem-like cells via downregulating both ATM and HIF-1α

Lung cancer is one of the main causes of cancer mortality globally. Most patients received radiotherapy during the course of disease. However, radioresistance generally occurs in the majority of these patients, leading to poor curative effect, and the underlying mechanism remains unclear. In the present study, miR-18a-5p expression was downregulated in irradiated lung cancer cells. Overexpression of miR-18a-5p increased the radiosensitivity of lung cancer cells and inhibited the growth of A549 xenografts after radiation exposure. Dual luciferase report system and miR-18a-5p overexpression identified ataxia telangiectasia mutated (ATM) and hypoxia inducible factor 1 alpha (HIF-1α) as the targets of miR-18a-5p. The mRNA and protein expressions of ATM and HIF-1α were dramatically downregulated by miR-18a-5p in vitro and in vivo. Clinically, plasma miR-18a-5p expression was significantly higher in radiosensitive than in radioresistant group (P < .001). The cutoff value of miR-18a-5p >2.28 was obtained from receiver operating characteristic (ROC) curve. The objective response rate (ORR) was significantly higher in miR-18a-5p-high group than in miR-18a-5p-low group (P < .001). A tendency demonstrated that the median local progression-free survival (PFS) from radiotherapy was longer in miR-18a-5p-high than in miR-18a-5p-low group (P = .082). The median overall survival (OS) from radiotherapy was numerically longer in miR-18a-5p-high than in miR-18a-5p-low group (P = .281). The sensitivity and specificity of plasma miR-18a-5p to predict radiosensitivity was 87% and 95%, respectively. Collectively, these results indicate that miR-18a-5p increases the radiosensitivity in lung cancer cells and CD133+ stem-like cells via downregulating ATM and HIF-1α expressions. Plasma miR-18a-5p would be an available indicator of radiosensitivity in lung cancer patients.

DNA-dependent protein kinase: Epigenetic alterations and the role in genomic stability of cancer

DNA-dependent protein kinase (DNA-PK), a member of phosphatidylinositol-kinase family, is a key protein in mammalian DNA double-strand break (DSB) repair that helps to maintain genomic integrity. DNA-PK also plays a central role in immune cell development and protects telomerase during cellular aging. Epigenetic deregulation due to endogenous and exogenous factors may affect the normal function of DNA-PK, which in turn could impair DNA repair and contribute to genomic instability. Recent studies implicate a role for epigenetics in the regulation of DNA-PK expression in normal and cancer cells, which may impact cancer progression and metastasis as well as provide opportunities for treatment and use of DNA-PK as a novel cancer biomarker. In addition, several small molecules and biological agents have been recently identified that can inhibit DNA-PK function or expression, and thus hold promise for cancer treatments. This review discusses the impact of epigenetic alterations and the expression of DNA-PK in relation to the DNA repair mechanisms with a focus on its differential levels in normal and cancer cells.

A meta-analysis of transcriptome datasets characterizes malignant transformation from melanocytes and nevi to melanoma

Melanoma represents one of the most aggressive malignancies and has a high tendency to metastasize. The present study aims to investigate the molecular mechanisms of two pathways to cancer transformation with the purpose of identifying potential biomarkers. Our approach is based on a meta-analysis of gene expression profiling contrasting two scenarios: A model that describes a transformation pathway from melanocyte to melanoma and a second model where transformation occurs through an intermediary nevus. Data consists of three independent, publicly available microarray datasets from the Gene Expression Omnibus (GEO) database comprising samples from melanocytes, nevi and melanoma. The present analysis identified 808 differentially expressed genes (528 upregulated and 360 downregulated) in melanoma compared with nevi, and 2,331 differentially expressed genes (946 upregulated and 1,385 downregulated) in melanoma compared with melanocytes. Further analysis narrowed down this list, since 682 differentially expressed genes were found in both models (417 upregulated and 265 downregulated). Enrichment analysis identified relevant dysregulated pathways. This article also presented a discussion on significant genes including ADAM like decysin 1, neudesin neurotrophic factor, MMP19, apolipoprotein L6, C-X-C motif chemokine ligand (CXCL)8, basic, immunoglobulin-like variable motif containing and CXCL16. These are of particular interest because they encode secreted proteins hence represent potential blood biomarkers for the early detection of malignant transformation in both scenarios. Cytotoxic T-lymphocyte associated protein 4, an important therapeutic target in melanoma treatment, was also upregulated in both comparisons indicating a potential involvement in immune tolerance, not only at advanced stages but also during the early transformation to melanoma. The results of the present study may provide a research direction for studying the mechanisms underlying the development of melanoma, depending on its origin.

MicroRNAs associated with therapy of non-small cell lung cancer

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

Unveiling massive numbers of cancer-related urinary-microRNA candidates via nanowires

Analyzing microRNAs (miRNAs) within urine extracellular vesicles (EVs) is important for realizing miRNA-based, simple, and noninvasive early disease diagnoses and timely medical checkups. However, the inherent difficulty in collecting dilute concentrations of EVs (<0.01 volume %) from urine has hindered the development of these diagnoses and medical checkups. We propose a device composed of nanowires anchored into a microfluidic substrate. This device enables EV collections at high efficiency and in situ extractions of various miRNAs of different sequences (around 1000 types) that significantly exceed the number of species being extracted by the conventional ultracentrifugation method. The mechanical stability of nanowires anchored into substrates during buffer flow and the electrostatic collection of EVs onto the nanowires are the two key mechanisms that ensure the success of the proposed device. In addition, we use our methodology to identify urinary miRNAs that could potentially serve as biomarkers for cancer not only for urologic malignancies (bladder and prostate) but also for nonurologic ones (lung, pancreas, and liver). The present device concept will provide a foundation for work toward the long-term goal of urine-based early diagnoses and medical checkups for cancer.

MicroRNA‑210 negatively regulates the radiosensitivity of nasopharyngeal carcinoma cells

Radiotherapy is one of the primary methods of treatment of malignant tumors, however, resistance to radiation is a major problem. The reasons for the radioresistance are still poorly understood. However, it is generally accepted that microRNAs (miRNAs or miRs) can regulate the radiosensitivity of tumors. The present study therefore aimed to identify specific miRNAs and their effects on radioresistant cells. More specifically, the aim was to investigate specific miRNAs and their effects on radioresistant tumor cells. The radioresistant tumor cells (CNE‑2R) were established using a dose gradient method, and the miRNA expression profiles of CNE‑2R cells and the parental cells (CNE‑2) were determined. The expression of miR‑210 in CNE‑2R cells was significantly higher than in CNE‑2 cells. CNE‑2R cells were transfected with LV‑hsa‑miR‑210‑inhibitor, and CNE‑2 cells were transfected with LV‑hsa‑miR‑210. The expression of miR‑210 was confirmed by reverse transcription quantitative‑polymerase chain reaction. The percentages of CNE‑2R‑miR‑210‑inhibitor and CNE‑2 cells in the G2/M phase were higher than in the CNE‑2R and CNE‑2‑miR‑210 cells, and the percentages of cells in S phase were lower than in the CNE‑2R and CNE‑2‑miR‑210 cells. Following 4 Gy of radiation, CNE‑2R‑miR‑210‑inhibitor and CNE‑2 cells, which express low levels of miR‑210, had a higher apoptosis rate than CNE‑2R and CNE‑2‑miR‑210 cells. Following 4, 8 and 12 Gy of radiation, cell viability and survival fraction of CNE‑2R‑miR‑210‑inhibitor cells were lower than those of CNE‑2R and CNE‑2‑miR‑210 cells, and similar to those of CNE‑2 cells. Together, these findings strongly suggest that miR‑210 negatively regulates the radiosensitivity of tumor cells, and may therefore have therapeutic potential for the treatment of radiation resistance.

MicroRNA-488-3p sensitizes malignant melanoma cells to cisplatin by targeting PRKDC

Deregulation of microRNAs (miRNAs) has been implicated in drug resistance in various types of cancers, including malignant melanoma (MM). MiR-488-3p has been reported as a tumor suppressor in several cancers. However, the exact expression patterns of miR-488-3p and the precise molecular mechanisms underlying its role in MM remain largely unknown and require further investigation. In this study, we demonstrated that miR-488-3p is significantly downregulated in MM clinical specimens and cell lines. Ectopic expression of miR-488-3p resulted in markedly increased drug sensitivity of MM cells in vitro and in vivo. The DNA-activated, catalytic polypeptide (PRKDC), which encodes DNA-dependent protein kinase catalytic subunit (DNA-PKcs), was identified as a direct target of miR-488-3p using luciferase reporter assays, qRT-PCR, and western blotting analyses. PRKDC knockdown by small interfering RNA (siRNA) alone promoted sensitivity of MM cells to cisplatin (DDP) while overexpression of PRKDC partially rescued the miR-488-3p-mediated acceleration of sensitivity to DDP in MM cells. Taken together, our results indicate that miR-488-3p serves as a drug resistance sensitizer in MM, supporting its potential as a promising therapeutic candidate.

MicroRNAs Involvement in Radioresistance of Head and Neck Cancer

Resistance to the ionizing radiation is a current problem in the treatment and clinical management of various cancers including head and neck cancer. There are several biological and molecular mechanisms described to be responsible for resistance of the tumors to radiotherapy. Among them, the main mechanisms include alterations in intracellular pathways involved in DNA damage and repair, apoptosis, proliferation, and angiogenesis. It has been found that regulation of these complex processes is often controlled by microRNAs. MicroRNAs are short endogenous RNA molecules that posttranscriptionally modulate gene expression and their deregulated expression has been observed in many tumors including head and neck cancer. Specific expression patterns of microRNAs have also been shown to predict prognosis and therapeutic response in head and neck cancer. Therefore, microRNAs present promising biomarkers and therapeutic targets that might overcome resistance to radiation and improve prognosis of head and neck cancer patients. In this review, we summarize the current knowledge of the functional role of microRNAs in radioresistance of cancer with special focus on head and neck cancer.

MicroRNA-124 regulates the radiosensitivity of non-small cell lung cancer cells by targeting TXNRD1

Radiation treatment remains one of the major modalities in the treatment of lung cancer. Although the majority of patients initially respond to treatment with radiation, resistance inevitably develops and leads to treatment failure. Therefore, the identification of the underlying molecular mechanisms of radiation resistance may facilitate the development of novel approaches for overcoming resistance, and enhance the efficacy of treatment with radiation in lung and other types of cancer. In the present study we established three radiation-resistant sub-cell lines derived from the radiation-sensitive lung cancer cell line HCC827. Using a polymerase chain reaction microRNA (miRNA) array, multiple miRNAs were identified to be markedly downregulated in radiation-resistant cells, including miRNA (miR)-124, miR-191 and miR-205. It was observed that overexpression of miR-124 sensitized the resistant cells to treatment with radiation and that thioredoxin reductase 1 (TXNRD1) is a novel target of miR-124. Furthermore, it was demonstrated that knockdown of TXNRD1 using small interfering RNA increased the basal level of reactive oxygen species and sensitized the cells to radiation treatment. The results of the present study demonstrated that multiple miRNAs are downregulated in radiation-resistant lung cancer cells and that downregulation of miR-124 mediates radiation resistance through the targeting of TXNRD1 mRNA expression. The present study revealed a novel molecular mechanism of miRNA-mediated radiation resistance and identified miR-124-regulated TXNRD1 as a novel therapeutic target for overcoming radiation resistance in the treatment of lung cancer.

Long Noncoding RNA GAS5 Inhibits Tumorigenesis and Enhances Radiosensitivity by Suppressing miR-135b Expression in Non-Small Cell Lung Cancer

Growth arrest-specific transcript 5 (GAS5) has been demonstrated to correlate with clinicopathological characteristics and serve as a tumor suppressor in non-small cell lung cancer (NSCLC). However, the underlying mechanism of the competing endogenous RNA (ceRNA) regulatory network involving GAS5 in NSCLC remains to be elucidated. In this study, qRT-PCR results showed that GAS5 was downregulated and miR-135b was upregulated in NSCLC tissues and cells. The expressions of GAS5 and miR-135b changed inversely in response to irradiation. Gain-of-function experiments revealed that GAS5 overexpression and miR-135b downregulation significantly suppressed tumorigenesis by repressing cell proliferation and invasion, and enhanced the radiosensitivity of NSCLC cells by reducing colony formation rates. Luciferase reporter assay confirmed that GAS5 could directly target miR-135b and negatively regulate its expression. Moreover, rescue experiments demonstrated that miR-135b upregulation markedly abolished GAS5 overexpression-induced tumorigenesis inhibition and radiosensitivity improvement. Furthermore, xenograft model analysis validated that GAS5 overexpression suppressed tumor growth and improved radiosensitivity of NSCLC cells in vivo. Taken together, GAS5 inhibits tumorigenesis and enhances radiosensitivity by suppressing miR-135b expression in NSCLC cells, deepening our understanding of the mechanism of miRNA-lncRNA interaction and providing a novel therapeutic strategy for NSCLC.

MicroRNAs and Their Impact on Radiotherapy for Cancer

Resistance to radiation is considered to be an important reason for local failure after radiotherapy and tumor recurrence. However, the exact mechanisms of tumor resistance remain poorly understood. Current investigations of microRNAs as potential diagnostic and therapeutic tools for cancer treatment have shown promising results. With respect to radiotherapy resistance and response, there is now emerging evidence that microRNAs modulate key cellular pathways that mediate response to radiation. These data suggest that microRNAs might have significant potential as targets for the development of new therapeutic strategies to overcome radioresistance in cancer. This review summarizes the current literature pertinent to the influence of microRNAs in the response to radiotherapy for cancer treatment, with an emphasis on microRNAs as novel diagnostic and prognostic markers, as well as their potential to alter radiosensitivity.

Knockdown of TC-1 enhances radiosensitivity of non-small cell lung cancer via the Wnt/β-catenin pathway

Thyroid cancer 1 (TC-1, C8ofr4) is widely expressed in vertebrates and associated with many kinds of tumors. Previous studies indicated that TC-1 functions as a positive regulator in the Wnt/β-catenin signaling pathway in non-small cell lung cancer (NSCLC). However, its exact role and regulation mechanism in radiosensitivity of NSCLC are still unclear. The expression level of TC-1 was measured by qRT-PCR and western blot in NSCLC cell lines. Proliferation and apoptosis of NSCLC cells in response to TC-1 knockdown or/and radiation were determined by MTT assay and flow cytometry, respectively. The activation of the Wnt/β-catenin signaling pathway was further examined by western blot in vitro and in vivo. Compared to TC-1 siRNA or radiotherapy alone, TC-1 silencing combined with radiation inhibited cell proliferation and induced apoptosis in NSCLC cell lines by inactivating of the Wnt/β-catenin signaling pathway. Furthermore, inhibition of the Wnt/β-catenin signaling pathway by XAV939, a Wnt/β-catenin signaling inhibitor, contributed to proliferation inhibition and apoptosis induction in NSCLC A549 cells. Combinative treatment of A549 xenografts with TC-1 siRNA and radiation caused significant tumor regression and inactivation of the Wnt/β-catenin signaling pathway relative to TC-1 siRNA or radiotherapy alone. The results from in vitro and in vivo studies indicated that TC-1 silencing sensitized NSCLC cell lines to radiotherapy through the Wnt/β-catenin signaling pathway.

Summary: TC-1 silencing inhibited cell proliferation and induced apoptosis in non-small cell lung cancer (NSCLC) both in vitro and in vivo through the Wnt/β-catenin signaling pathway, thereby increasing the susceptibility of NSCLC to radiotherapy.