Recent advances of microRNA-based molecular diagnostics to reduce false-positive lung cancer imaging

Non-invasive detection of tumor markers in salivary extracellular vesicles based on digital PCR chips

The World Health Organization (WHO) has stated that countless cancer patients could be saved if early detection and treatment were available. However, current clinical evaluation of tumors still relies primarily on imaging examinations and tissue biopsies. These methods not only require sophisticated equipment, but also have high false positive rates or invasive problems. Here, we describe a digital polymerase chain reaction (dPCR) chip for the detection of biomarkers in salivary extracellular vesicles (SEVs), which can be used to identify markers for the early diagnosis of tumors. Based on microfluidic technology fine microstructure and microfluidics operations, this dPCR chip can accurate quantitative SEVs in a variety of tumor markers, and shows extremely strong sensitivity (10 copies). In the detection of clinical samples, the chip can effectively distinguish lung cancer cases from normal controls (P < 0.001; two-tailed t-test), and in the detection of extremely low concentration samples, it shows considerably higher precise quantitative ability than quantitative real-time polymerase chain reaction (qPCR). Overall, this study may shed new light on non-invasive early screening of tumor markers by detecting extracellular vesicle-associated markers in saliva.

Impact of low-dose computed tomography (LDCT) screening on lung cancer-related mortality

BACKGROUND

Lung cancer is the most common cause of cancer-related death in the world, however lung cancer screening has not been implemented in most countries at a population level. A previous Cochrane Review found limited evidence for the effectiveness of lung cancer screening with chest radiography (CXR) or sputum cytology in reducing lung cancer-related mortality, however there has been increasing evidence supporting screening with low-dose computed tomography (LDCT).  OBJECTIVES: To determine whether screening for lung cancer using LDCT of the chest reduces lung cancer-related mortality and to evaluate the possible harms of LDCT screening.

SEARCH METHODS

We performed the search in collaboration with the Information Specialist of the Cochrane Lung Cancer Group and included the Cochrane Lung Cancer Group Trial Register, Cochrane Central Register of Controlled Trials (CENTRAL, the Cochrane Library, current issue), MEDLINE (accessed via PubMed) and Embase in our search. We also searched the clinical trial registries to identify unpublished and ongoing trials. We did not impose any restriction on language of publication. The search was performed up to 31 July 2021.  SELECTION CRITERIA: Randomised controlled trials (RCTs) of lung cancer screening using LDCT and reporting mortality or harm outcomes.  DATA COLLECTION AND ANALYSIS: Two review authors were involved in independently assessing trials for eligibility, extraction of trial data and characteristics, and assessing risk of bias of the included trials using the Cochrane RoB 1 tool. We assessed the certainty of evidence using GRADE. Primary outcomes were lung cancer-related mortality and harms of screening. We performed a meta-analysis, where appropriate, for all outcomes using a random-effects model. We only included trials in the analysis of mortality outcomes if they had at least 5 years of follow-up. We reported risk ratios (RRs) and hazard ratios (HRs), with 95% confidence intervals (CIs) and used the I2 statistic to investigate heterogeneity.  MAIN RESULTS: We included 11 trials in this review with a total of 94,445 participants. Trials were conducted in Europe and the USA in people aged 40 years or older, with most trials having an entry requirement of ≥ 20 pack-year smoking history (e.g. 1 pack of cigarettes/day for 20 years or 2 packs/day for 10 years etc.). One trial included male participants only. Eight trials were phase three RCTs, with two feasibility RCTs and one pilot RCT. Seven of the included trials had no screening as a comparison, and four trials had CXR screening as a comparator. Screening frequency included annual, biennial and incrementing intervals. The duration of screening ranged from 1 year to 10 years. Mortality follow-up was from 5 years to approximately 12 years.  None of the included trials were at low risk of bias across all domains. The certainty of evidence was moderate to low across different outcomes, as assessed by GRADE. In the meta-analysis of trials assessing lung cancer-related mortality, we included eight trials (91,122 participants), and there was a reduction in mortality of 21% with LDCT screening compared to control groups of no screening or CXR screening (RR 0.79, 95% CI 0.72 to 0.87; 8 trials, 91,122 participants; moderate-certainty evidence). There were probably no differences in subgroups for analyses by control type, sex, geographical region, and nodule management algorithm. Females appeared to have a larger lung cancer-related mortality benefit compared to males with LDCT screening. There was also a reduction in all-cause mortality (including lung cancer-related) of 5% (RR 0.95, 95% CI 0.91 to 0.99; 8 trials, 91,107 participants; moderate-certainty evidence).  Invasive tests occurred more frequently in the LDCT group (RR 2.60, 95% CI 2.41 to 2.80; 3 trials, 60,003 participants; moderate-certainty evidence). However, analysis of 60-day postoperative mortality was not significant between groups (RR 0.68, 95% CI 0.24 to 1.94; 2 trials, 409 participants; moderate-certainty evidence).  False-positive results and recall rates were higher with LDCT screening compared to screening with CXR, however there was low-certainty evidence in the meta-analyses due to heterogeneity and risk of bias concerns. Estimated overdiagnosis with LDCT screening was 18%, however the 95% CI was 0 to 36% (risk difference (RD) 0.18, 95% CI -0.00 to 0.36; 5 trials, 28,656 participants; low-certainty evidence). Four trials compared different aspects of health-related quality of life (HRQoL) using various measures. Anxiety was pooled from three trials, with participants in LDCT screening reporting lower anxiety scores than in the control group (standardised mean difference (SMD) -0.43, 95% CI -0.59 to -0.27; 3 trials, 8153 participants; low-certainty evidence). There were insufficient data to comment on the impact of LDCT screening on smoking behaviour.  AUTHORS' CONCLUSIONS: The current evidence supports a reduction in lung cancer-related mortality with the use of LDCT for lung cancer screening in high-risk populations (those over the age of 40 with a significant smoking exposure). However, there are limited data on harms and further trials are required to determine participant selection and optimal frequency and duration of screening, with potential for significant overdiagnosis of lung cancer. Trials are ongoing for lung cancer screening in non-smokers.

MiR-205-5p promotes lung cancer progression and is valuable for the diagnosis of lung cancer

BACKGROUND

MicroRNAs (miRNAs) function as potential diagnostic biomarkers in various cancers. This study aimed to evaluate the roles of miR-205-5p in lung cancer progression and diagnosis.

MATERIALS AND METHODS

MiR-205-5p was detected by quantitative real-time PCR. The effect of miR-205-5p on cell proliferation and metastasis was estimated by MTT and flow cytometry. The expression of TP53INP1 and related genes was analyzed by immunoblotting. The diagnostic value of miR-205-5p was analyzed using receiver operating characteristic (ROC) curve analysis, sensitivity, and specificity.

RESULTS

The miR-205-5p was increased in lung cancer tissues. MiR-205-5p mimics were promoted but its inhibitor suppressed cell proliferation and metastasis compared with control treatment in vitro and in vivo. By regulating the 3' untranslated region, miR-205-5p could negatively regulate TP53INP1 expression, which further inhibited the expression of RB1 and P21, but increased that of cyclinD1. Moreover, the serum miR-205-5p levels of patients with lung cancer were significantly higher than those of normal controls, and they were correlated with patients' gender, drinking status, and clinical stage. The area under the ROC curve of serum miR-205-5p in the diagnosis of non-small-cell lung cancer was 0.8250, respectively. The finding supported its possession of high diagnostic efficiency for lung cancer.

CONCLUSIONS

MiR-205-5p promoted lung cancer cell proliferation and metastasis by negatively regulating the novel target TP53INP1, which further affected the expression of P21, RB1, and cyclin D1. Serum miR-205-5p is a novel and valuable biomarker for lung cancer diagnosis.

Delivery of miR-320a-3p by gold nanoparticles combined with photothermal therapy for directly targeting Sp1 in lung cancer

Lung cancer is the second most common tumor and has the highest mortality rate. Both novel therapeutic targets and approaches are needed to improve the overall survival of patients with lung cancer. MicroRNA-320a-3p belongs to the miR-320a family and has been reported as a tumor suppressor in multiple cancers. However, its definitive role and precise mechanism in the progression of lung cancer remain unclear. In this study, we developed a new type of gold nanorod modified with polyethyleneimine that targets cancer-specific nanoparticles by RGD peptide, which could condense miRNA to self-assemble supramolecular nanoparticles. The designed nanoparticles can achieve integrin αvβ3-targeted cancer therapy, realize photosensitive therapy by laser irradiation and attain gene-targeted therapy by miRNAs. These nanoparticles could deliver miR-320a into lung cancer cells specifically and efficiently. Moreover, we demonstrated that Au-RGD-miR-320a nanoparticles combined with laser irradiation dramatically inhibited the proliferation and metastasis, and enhanced the apoptosis of lung cancer, both in vitro and in vivo. In terms of the mechanism, miR-320a inhibits Sp1 expression by directly binding to the 3'UTR of Sp1, and it eventually enhanced the expression of PTEN and inhibited the expression of matrix metallopeptidase 9 (MMP9). These findings provide a new and promising anticancer strategy via the use of Au-RGD-miR-320a nanoparticles, and identify miR-320a/Sp1 as a potential target for future systemic therapy against lung cancer.

Circulating extracellular vesicles from individuals at high-risk of lung cancer induce pro-tumorigenic conversion of stromal cells through transfer of miR-126 and miR-320

BACKGROUND

Extracellular vesicles (EVs) containing specific subsets of functional biomolecules are released by all cell types and analysis of circulating EVs can provide diagnostic and prognostic information. To date, little is known regarding the role of EVs both as biomarkers and potential key players in human lung cancer.

METHODS

Plasma EVs were isolated from 40 cancer-free heavy-smokers classified according to a validated 24-microRNA signature classifier (MSC) at high (MSCpos-EVs) or low (MSCneg-EVs) risk to develop lung cancer. EVs origin and functional properties were investigated using in vitro 3D cultures and in vivo models. The prognostic value of miRNAs inside EVs was assessed in training and in validation cohorts of 54 and 48 lung cancer patients, respectively.

RESULTS

Different membrane composition, biological cargo and pro-tumorigenic activity were observed in MSCpos vs MSCneg-EVs. Mechanistically, in vitro and in vivo results showed that miR-126 and miR-320 from MSCpos-EVs increased pro-angiogenic phenotype of endothelial cells and M2 polarization of macrophage, respectively. MSCpos-EVs prompted 3D proliferation of non-tumorigenic epithelial cells through c-Myc transfer. Moreover, hypoxia was shown to stimulate the secretion of EVs containing c-Myc from fibroblasts, miR-126-EVs from endothelial cells and miR-320-EVs from granulocytes. Lung cancer patients with higher levels of mir-320 into EVs displayed a significantly shorter overall survival in training [HR2.96] and validation sets [HR2.68].

CONCLUSION

Overall our data provide a new perspective on the pro-tumorigenic role of circulating EVs in high risk smokers and highlight the significance of miR-320-EVs as a new prognostic biomarker in lung cancer patients.

c-Myc shuttled by tumour-derived extracellular vesicles promotes lung bronchial cell proliferation through miR-19b and miR-92a

Lung cancer causes approximately one fifth of all cancer deaths. Tumour cells actively communicate with the surrounding microenvironment to support malignant progression. Extracellular vesicles (EVs) play a pivotal role in intercellular communication and modulate recipient cells by delivering their contents, including proteins and nucleic acids such as microRNAs (miRNAs). We isolated EVs from the conditioned medium (CM) of human lung cancer cell lines and plasma of lung cancer patients and cancer-free smokers using an ultracentrifugation method. A significant increase in bronchial HBEC-KRAS^V12high cell proliferation, confirmed by cell cycle analysis, was observed after treatment with cancer-derived EVs. Lung cancer-derived EVs induced transcription of the pri-miR-92a gene, resulting in the overexpression of mature miR-19b and miR-92a in recipient bronchial cells. Modulation of these two miRNAs using miRNA mimics or inhibitors confirmed their ability to promote proliferation. In silico analysis and experimental validation showed that miR-19b and miR-92a impaired the TGF-beta (TGFB) pathway and identified TGFBRI and TGFBRII as target genes involved in EV-mediated bronchial cell proliferation. Interestingly, the oncoprotein c-Myc, a well-known miR-17-92 cluster activator, was detected only in the EVs derived from lung cancer patients and cell lines and was able to modulate the proliferation of HBEC-KRAS^V12high recipient cells. These data support the role of c-Myc shuttling in lung cancer-derived EVs in inducing the upregulation of onco-miR-19b and miR-92a expression with concomitant impairment of the TGFB signalling pathway in recipient cells.

Down-regulation of microRNA-200b is a potential prognostic marker of lung cancer in southern-central Chinese population

MicroRNAs (miRNAs) may regulate diverse biological processes and play an important role in cancer. And MiRNAs have been proposed as a useful tool for lung cancer diagnosis and therapeutics in cancer. The purpose of the present study was to investigate the association among the expression level of mature miR-200b-5p in peripheral blood and the risk of lung cancer and clinic pathological characteristics. This case-control study included 24 patients with lung cancer and 12 healthy controls. MiR-200b expression was deleted using real-time PCR. and the miR-200b expression of normal controls was significantly higher than that in lung cancer patients (1732.13 pg/mL vs 881.67 pg/mL, P < 0.05), no difference with age, sex, tissue type and clinical stage of lung cancer patients (P > 0.05). Furthermore, miR-200b expression level fluctuated with tumor progression in lung cancer, and there was highly significant for clinical stage II compared with the clinical stage III (P < 0.05). In addition, the down-regulation of miR-200b showed a highly discriminative receiver operating characteristic (ROC) curve profile, clearly distinguishing cancer patients from cancer-free subjects with an area under the ROC curve (AUROC) of 0.87. The detection of miR-200b expression yielded 83.30% sensitivity and 100.00% specificity in the diagnosis of lung cancer. Therefore, these findings suggested that miR-200b may be used as a marker for the detection and diagnosis of lung cancer in peripheral blood.

Biomarkers in Lung Cancer Screening: Achievements, Promises, and Challenges

The present review is an update of the research and development efforts regarding the use of molecular biomarkers in the lung cancer screening setting. The two main unmet clinical needs, namely, the refinement of risk to improve the selection of individuals undergoing screening and the characterization of undetermined nodules found during the computed tomography-based screening process are the object of the biomarkers described in the present review. We first propose some principles to optimize lung cancer biomarker discovery projects. Then, we summarize the discovery and developmental status of currently promising molecular candidates, such as autoantibodies, complement fragments, microRNAs, circulating tumor DNA, DNA methylation, blood protein profiling, or RNA airway or nasal signatures. We also mention other emerging biomarkers or new technologies to follow, such as exhaled breath biomarkers, metabolomics, sputum cell imaging, genetic predisposition studies, and the integration of next-generation sequencing into study of circulating DNA. We also underline the importance of integrating different molecular technologies together with imaging, radiomics, and artificial intelligence. We list a number of completed, ongoing, or planned trials to show the clinical utility of molecular biomarkers. Finally, we comment on future research challenges in the field of biomarkers in the context of lung cancer screening and propose a design of a trial to test the clinical utility of one or several candidate biomarkers.

MicroRNA-212 suppresses nonsmall lung cancer invasion and migration by regulating ubiquitin-specific protease-9

MicroRNAs (miRNAs) play crucial roles in various biological processes, including migration, proliferation, differentiation, cell cycling, and apoptosis. Epithelial-mesenchymal transition (EMT) has been shown to be related to the capability of migration and invasion in many tumor cells. In this study, we used wound-healing assay and transwell invasion to analysis the capability of migration and invasion in non-small-cell lung carcinoma (NSCLC), respectively. The expression of ubiquitin-specific protease-9-X-linked (USP9X) and miR-212 messenger RNA (mRNA) was determined by quantitative real-time polymerase chain reaction and Western blot analysis was used to determine the E-cadherin and vimentin expression. Our results showed that miR-212 mimic inhibited cell migration and invasion, while miR-212 inhibitor increased cell migration and invasion. There was no significant difference between WP1130 and miR-212 mimic combined with WP1130 groups. Moreover, WP1130 inhibited the capability of the migration and invasion of NSCLC cells. Western blot analysis displayed that miR-212 mimic upregulated E-cadherin expression and downregulated vimentin expression, while miR-212 inhibitor downregulated E-cadherin and upregulated vimentin expression. These data showed that miR-212 regulated NSCLC cell invasion and migration by regulating USP9X expression. Taken together, these findings indicated that miR-212 regulated NSCLC cells migration and invasion through targeting USP9X involved in EMT.

microRNA-107 inhibits gastric cancer cell proliferation and metastasis by targeting PI3K/AKT pathway

The present study was aimed to investigate the effect of miR-107 transfection on gastric cancer cell growth. Results from qRT-PCR revealed that level of miR-107 in SGC-7901 and MKN1 cell lines was down-regulated in comparison to the normal cells, GES-1. CCK-8 assay revealed a significant reduction in the proliferation of SGC-7901 cells on transfection with miR-107. The tumor growth was very slow in the mice implanted with SGC-7901/miR-107 compared to those bearing SGC-7901/miR-NC. In SGC-7901 cells metastasis potential after miR-107 transfection was examined using wound-healing and Transwell invasion assays. The migration as well as invasion potential of SGC-7901 cells was significantly lower on transfection with miR-107. The activity of luciferase was reduced markedly in SGC-7901 cells co-transfected with miR-107 mimic compared to miR-NC. However, miR-107 mimic co-transfection did not affect the luciferase activity in SGC-7901 cells bearing mutant-type BDNF 3'UTR. Western blot assay showed that miR-107 overexpression causes inhibition of BDNF mRNA and protein expression in SGC-7901 cells. The CCK8 assay showed that pBDNF transfection prevented miR-107 mediated inhibition of SGC-7901 cell proliferation. miR-107 mimic transfection inhibited expression of BDNF and activation of PI3K (p-PI3K) and AKT (p-AKT) in SGC-7901 cells. In order to confirm whether activation of PI3K and AKT by miR-107 mimic involves inhibition of BDNF, the cells were co-transfected with si-BDNF. The results revealed that si-BDNF transfection led to inhibition of BDNF expression and PI3K and AKT activation in SGC-7901 cells. In summary, the present study demonstrates that miR-107 expression inhibits proliferation and metastasis in gastric cancer cells. Therefore, miR-107 acts as tumor inhibitor for gastric cancer through targeting BDNF expression. Thus miR-107 can be used for treatment of gastric cancer.

miR‑185 inhibits non‑small cell lung cancer cell proliferation and invasion through targeting of SOX9 and regulation of Wnt signaling

SRY-box 9 (SOX9) is an important transcription factor required for development, which has additionally been reported to be an independent prognostic indicator for the survival of patients with non‑small cell lung cancer (NSCLC). Accumulating evidence has indicated that dysregulation of microRNAs (miRNAs/miRs) may contribute to the initiation and progression of cancer. SOX9 may be regulated by a number of miRNAs in different types of cancer, including in NSCLC. The present study sought to identify novel candidate miRNAs associated with SOX9 in NSCLC using online tools, and investigated the detailed functions of miR‑185, which suppressed SOX9 mRNA expression most strongly out of the candidate miRNAs. It was observed that ectopic miR‑185 expression significantly suppressed NSCLC cell proliferation, invasion and migration. Using luciferase reporter gene and RNA immunoprecipitation assays, SOX9 was confirmed to be a direct target of miR‑185. In addition, the downstream Wnt signaling‑associated factors β‑catenin and c‑Myc proto‑oncogene protein (Myc) were demonstrated to be inhibited by miR‑185 overexpression. SOX9, β‑catenin and c‑Myc mRNA expression was significantly upregulated in NSCLC tissues, and was inversely correlated with miR‑185 expression. The results of the present study demonstrated that rescuing miR‑185 expression in NSCLC, thereby inhibiting SOX9 expression and the downstream Wnt signaling, and leading to the suppression of NSCLC cell proliferation, invasion and migration, may be a promising strategy for the treatment of NSCLC.

Seven-microRNA panel for lung adenocarcinoma early diagnosis in patients presenting with ground-glass nodules

Background

MicroRNA (miRNA) expression is correlated with tumor histology, differentiation, invasiveness and treatment outcome. We aimed to identify miRNAs whose differential expression might enable early diagnosis of lung adenocarcinoma in patients presenting with ground-glass nodules (GGNs).

Methods

To identify potential miRNAs of interest, we analyzed the miRNA expression profile of tumor and adjacent non-para-tumor tissue in three participants by next-generation sequencing (NGS). We then assessed the expression levels of the miRNAs of interest in 73 lung adenocarcinomas presenting with GGNs with matched adjacent non-tumor tissue by quantitative real-time polymerase chain reaction (qRT-PCR). We also detected the miRNA panel in 66 lung benign diseases and 66 lung adenocarcinomas presenting with GGN lesion tissues by qRT-PCR. Target genes of our selected miRNA panel were predicted using Miranda with default parameters.

Results

Twenty-three miRNAs showed differential expression between tumor and adjacent non-tumor tissue by NGS. Five miRNAs exhibited higher expression in tumor tissue compared to adjacent non-tumor tissue (P<0.05); 18 miRNAs demonstrated lower expression in tumor tissue versus adjacent non-tumor tissue (P<0.05). When qRT-PCR was performed for the 23 miRNAs identified by NGS in the pilot stage, seven were found to have statistically significant expression in tumor versus adjacent non-tumor tissue (P<0.05). The sensitivity and specificity of seven-miRNA panel were 86.4% and 60.6%, respectively.

Conclusion

The predicted targets of our miRNAs of interest are frequently associated with cancer signaling pathways. We developed a miRNA panel that could potentially predict the presence of lung adenocarcinoma in patients presenting with GGNs.

Systematic review and critique of circulating miRNAs as biomarkers of stage I-II non-small cell lung cancer

Selected circulating microRNAs (miRNAs) have been suggested for non-invasive screening of non-small cell lung cancer (NSCLC), however the numerous proposed miRNA signatures are inconsistent. Aiming to identify miRNAs suitable specifically for stage I-II NSCLC screening in serum/plasma samples, we searched the databases "Pubmed", "Medline", "Scopus", "Embase" and "WOS" and systematically reviewed the publications reporting quantitative data on the efficacy [sensitivity, specificity and/or area under the curve (AUC)] of circulating miRNAs as biomarkers of NSCLC stage I and/or II. The 20 studies fulfilling the search criteria included 1110 NSCLC patients and 1009 controls, and were of medium quality according to Quality Assessment of Diagnostic Accuracy Studies checklist. In these studies, the patient cohorts as well as the control groups were heterogeneous for demographics and clinicopathological characteristics; moreover, numerous pre-analytical and analytical variables likely influenced miRNA determinations, and potential bias of hemolysis was often underestimated. We identified four circulating miRNAs scarcely influenced by hemolysis, each featuring high sensitivity (> 80%) and AUC (> 0.80) as biomarkers of stage I-II NSCLC: miR-223, miR-20a, miR-448 and miR-145; four other miRNAs showed high specificity (> 90%): miR-628-3p, miR-29c, miR-210 and miR-1244. In a model of two-step screening for stage I-II NSCLC using first the above panel of serum miRNAs with high sensitivity and high AUC, and subsequently the panel with high specificity, the estimated overall sensitivity is 91.6% and overall specificity is 93.4%. These and other circulating miRNAs suggested for stage I-II NSCLC screening require validation in multiple independent studies before they can be proposed for clinical application.

MicroRNA Based Liquid Biopsy: The Experience of the Plasma miRNA Signature Classifier (MSC) for Lung Cancer Screening

The development of a minimally invasive test, such as liquid biopsy, for early lung cancer detection in its preclinical phase is crucial to improve the outcome of this deadly disease. MicroRNAs (miRNAs) are tissue specific, small, non-coding RNAs regulating gene expression, which may act as extracellular messengers of biological signals derived from the cross-talk between the tumor and its surrounding microenvironment. They could thus represent ideal candidates for early detection of lung cancer. In this work, a methodological workflow for the prospective validation of a circulating miRNA test using custom made microfluidic cards and quantitative Real-Time PCR in plasma samples of volunteers enrolled in a lung cancer screening trial is proposed. In addition, since the release of hemolysis-related miRNAs and more general technical issues may affect the analysis, the quality control steps included in the standard operating procedures are also presented. The protocol is reproducible and gives reliable quantitative results; however, when using large clinical series, both pre-analytical and analytical features should be cautiously evaluated.

Inhibition of miR-32 activity promoted EMT induced by PM2.5 exposure through the modulation of the Smad1-mediated signaling pathways in lung cancer cells

Epithelial mesenchymal transition (EMT) is a crucial morphological event during tumor progression. The present study reported that EMT could be triggered by airborne fine particulate matter (PM) with a mean diameter of less than 2.5 μm (PM2.5) in human lung cancer cells. We also aimed to elucidate the possible mechanisms of these processes. The results showed that treatment with PM2.5 promoted the activity of the SMAD family member 1 (Smad1)-mediated signaling pathway and downregulated the expression of the inhibitory Smad proteins Smad6 and Smad7 in lung cancer cells. Moreover, the knockdown of Smad1 suppressed the EMT process induced by PM2.5 exposure. Our data further revealed that miR-32 has a negative effect on PM2.5-induced EMT. The results showed that the expression level of miR-32 was significantly upregulated in the PM2.5-induced EMT process. The knockdown of miR-32 enhances the activity of the Smad1-mediated signaling pathway, which promotes the EMT process induced by PM2.5. Thus, these findings indicate that PM2.5 can induce the EMT process through the Smad1-mediated signaling pathway, and miR-32 may act as an EMT inhibitor in lung cancer cells.

Circulating cell-free microRNAs as clinical cancer biomarkers

MicroRNAs (miRNAs) are non-coding small RNAs that are master regulators of genic expression and consequently of many cellular processes. But their expression is often deregulated in human tumors leading to cancer development. Recently miRNAs were discovered in body fluids (serum, plasma and others) and their levels have often been reported to be altered in patients. Circulating miRNAs became one of the most promising biomarkers in oncology for early diagnosis, prognosis and therapeutic response prediction. Here we describe the origins and roles of miRNAs, and summarize the most recent studies focusing on their usefulness as cancer biomarkers in lung, breast, colon, prostate, ovary cancers and melanoma. Lastly, we describe the main methodologies related to miRNA detection, which should be standardized for their use in clinical practice.

Mutational Profile from Targeted NGS Predicts Survival in LDCT Screening-Detected Lung Cancers

Background:

The issue of overdiagnosis in low-dose computed tomography (LDCT) screening trials could be addressed by the development of complementary bio-markers able to improve detection of aggressive disease. The mutation profile of LDCT screening–detected lung tumors is currently unknown.

Methods:

Targeted next-generation sequencing was performed on 94 LDCT screening–detected lung tumors. Associations with clinicopathologic features, survival, and the risk profile of a plasma microRNA signature classifier were analyzed.

Results:

The mutational spectrum and frequency observed in screening series was similar to that reported in public data sets, although a larger number of tumors without mutations in driver genes was detected. The 5-year overall survival (OS) rates of patients with and without mutations in the tumors were 66% and 100%, respectively (p = 0.015). By combining the mutational status with the microRNA signature classifier risk profile, patients were stratified into three groups with 5-year OS rates ranging from 42% to 97% (p < 0.0001) and the prognostic value was significant after controlling for stage (p = 0.02).

Conclusion:

Tumor mutational status along with a microRNA-based liquid biopsy can provide additional information in planning clinical follow-up in lung cancer LDCT screening programs.

MicroRNA-520e suppresses non-small-cell lung cancer cell growth by targeting Zbtb7a-mediated Wnt signaling pathway

MicroRNAs (miRNAs) that negatively regulated gene expression have emerged as novel therapeutic target for non-small-cell lung cancer (NSCLC) treatment. In this study, we investigated the potential role of miR-520e and examined its functional role in NSCLCs. Loss-and-gain of function assays show that miR-520e significantly modulated NSCLC cell growth, cell invasion and cell migration via directly targeting the 3'-untranslated region (UTR) of Zbtb7a and therefore reduced Zbtb7a protein level. These effects of miR-520e on NSCLC progression could be rescued by Zbtb7a overexpression in A549 cells. Furthermore, both of miR-520e level and Zbtb7a level were correlated with Wnt signaling in NSCLC cells. Taken together, these results indicate that overexpressing miR-520e is involved in regulating the NSCLC cell growth, invasion and migration by targeting Zbtb7a partly depending on Wnt signaling.

The roles of miRNAs as potential biomarkers in lung diseases

MicroRNAs (miRNAs) are small non-coding RNAs which can act as master regulators of gene expression, modulate almost all biological process and are essential for maintaining cellular homeostasis. Dysregulation of miRNA expression has been associated with aberrant gene expression and may lead to pathological conditions. Evidence suggests that miRNA expression profiles are altered between health and disease and as such may be considered as biomarkers of disease. Evidence is increasing that miRNAs are particularly important in lung homeostasis and development and have been demonstrated to be the involved in many pulmonary diseases such as asthma, COPD, sarcoidosis, lung cancer and other smoking related diseases. Better understanding of the function of miRNA and the mechanisms underlying their action in the lung, would help to improve current diagnosis and therapeutics strategies in pulmonary diseases. Recently, some miRNA-based drugs have been introduced as possible therapeutic agents. In this review we aim to summarize the recent findings regarding the role of miRNAs in the airways and lung and emphasise their potential therapeutic roles in pulmonary diseases.

Circulating microRNA signature as liquid-biopsy to monitor lung cancer in low-dose computed tomography screening

Liquid biopsies can detect biomarkers carrying information on the development and progression of cancer. We demonstrated that a 24 plasma-based microRNA signature classifier (MSC) was capable of increasing the specificity of low dose computed tomography (LDCT) in a lung cancer screening trial. In the present study, we tested the prognostic performance of MSC, and its ability to monitor disease status recurrence in LDCT screening-detected lung cancers.Between 2000 and 2010, 3411 heavy smokers enrolled in two screening programmes, underwent annual or biennial LDCT. During the first five years of screening, 84 lung cancer patients were classified according to one of the three MSC levels of risk: high, intermediate or low. Kaplan-Meier survival analysis was performed according to MSC and clinico-pathological information. Follow-up MSC analysis was performed on longitudinal plasma samples (n = 100) collected from 31 patients before and after surgical resection.Five-year survival was 88.9% for low risk, 79.5% for intermediate risk and 40.1% for high risk MSC (p = 0.001). The prognostic power of MSC persisted after adjusting for tumor stage (p = 0.02) and when the analysis was restricted to LDCT-detected cases after exclusion of interval cancers (p < 0.001). The MSC risk level decreased after surgery in 76% of the 25 high-intermediate subjects who remained disease free, whereas in relapsing patients an increase of the MSC risk level was observed at the time of detection of second primary tumor or metastatic progression.These results encourage exploiting the MSC test for lung cancer monitoring in LDCT screening for lung cancer.

MicroRNA-107 inhibits tumor growth and metastasis by targeting the BDNF-mediated PI3K/AKT pathway in human non-small lung cancer

Abnormal expression of microRNA-107 (miR-107) was found in non-small cell lung cancer (NSCLC). However, little is known about its role and molecular mechanism in NSCLC progression and metastasis. Therefore, the aims of this study were to clarify the potential role of miR-107 and molecular mechanism in NSCLC progression and metastasis. Quantitative real-time polymerase chain reaction assay showed that miR-107 expression levels were significantly decreased in NSCLC tissue and cell lines. Low miR-107 levels in tumor tissue correlated with advanced TNM stage and lymph node metastasis. Function assays showed that overexpression of miR-107 suppressed cell proliferation, migration and invasion in A549 cells in vitro, and inhibited NSCLC tumor growth in vivo. Further mechanism assays suggested the brain-derived neurotrophic factor (BDNF) was identified as a target gene of miR-107 in NSCLC cells. In addition, BDNF expression was upregulated, and inversely correlated with miR-107 in NSCLC tissues. Enforced overexpression of BDNF effectively reversed the tumor suppressive functions of miR-107 on NSCLC proliferation, migration and invasion. miR-107 overexpression or downregulation of BDNF was able to inhibit activation of PI3K/AKT signaling pathway. Taken together, our findings present the first evidence that miR-107 could suppress NSCLC metastasis by targeting BDNF and indirectly regulating PI3K/AKT signaling pathway, which might lead to a potential therapeutic strategy focusing on miR-107 and BDNF for human NSCLC.

MicroRNA Profile of Lung Tumor Tissues Is Associated with a High Risk Plasma miRNA Signature

Lung cancer is the most common cause of cancer deaths worldwide. MicroRNAs (miRNAs) are short, non-coding RNAs that regulate gene expression. Many studies have reported that alterations in miRNA expression are involved in several human tumors. We have previously identified a circulating miRNA signature classifier (MSC) able to discriminate lung cancer with more aggressive features. In the present work, microarray miRNA profiling of tumor tissues collected from 19 lung cancer patients with an available MSC result were perform in order to find a possible association between miRNA expression and the MSC risk level. Eleven tissue mature miRNAs and six miRNA precursors were observed to be associated with the plasma MSC risk level of patients. Not one of these miRNAs was included in the MSC algorithm. A pathway enrichment analysis revealed a role of these miRNA in the main pathways determining lung cancer aggressiveness. Overall, these findings add to the knowledge that tissue and plasma miRNAs behave as excellent diagnostic and prognostic biomarkers, which may find rapid application in clinical settings.

miR-154 inhibits migration and invasion of human non-small cell lung cancer by targeting ZEB2

Emerging evidence suggests that microRNAs (miRs) play critical roles in the development and progression of non-small cell lung cancer (NSCLC). In a previous study, the present authors demonstrated that miR-154 acts as a tumor suppressor in NSCLC; however, its underlying molecular mechanism and target in NSCLC remain poorly understood. In the present study, ectopic expression of miR-154 remarkably suppressed cell migration and invasion in NSCLC cells. Zinc finger E-box binding homeobox 2 (ZEB2) was identified as a direct target of miR-154 in NSCLC cells. Furthermore, overexpression of miR-154 could decrease the expression of ZEB2 at the messenger RNA and protein levels. Ectopic expression of miR-154 also increased the levels of E-cadherin, an epithelial marker, and decreased the levels of vimentin, a mesenchymal marker, which contributed to suppress epithelial-mesenchymal transition (EMT) and to inhibit cell migration and invasion. In addition, downregulation of ZEB2 exerted similar effects to those caused by miR-154 overexpression on NSCLC cell migration and invasion, while upregulation of ZEB2 could significantly reverse the inhibitory effects on migration and invasion caused by miR-154 on NSCLC cells. These findings demonstrated that miR-154 inhibited migration and invasion of NSCLC cells by regulating EMT through targeting ZEB2, suggesting that miR-154 may be a potential anticancer therapeutic target for NSCLC.

Novel method to detect microRNAs using chip-based QuantStudio 3D digital PCR

Background

Research efforts for the management of cancer, in particular for lung cancer, are directed to identify new strategies for its early detection. MicroRNAs (miRNAs) are a new promising class of circulating biomarkers for cancer detection, but lack of consensus on data normalization methods has affected the diagnostic potential of circulating miRNAs. There is a growing interest in techniques that allow an absolute quantification of miRNAs which could be useful for early diagnosis. Recently, digital PCR, mainly based on droplets generation, emerged as an affordable technology for precise and absolute quantification of nucleic acids.

Results

In this work, we described a new interesting approach for profiling circulating miRNAs in plasma samples using a chip-based platform, the QuantStudio 3D digital PCR. The proposed method was validated using synthethic oligonucleotide at serial dilutions in plasma samples of lung cancer patients and in lung tissues and cell lines.

Conclusion

Given its reproducibility and reliability, our approach could be potentially applied for the identification and quantification of miRNAs in other biological samples such as circulating exosomes or protein complexes. As chip-digital PCR becomes more established, it would be a robust tool for quantitative assessment of miRNA copy number for diagnosis of lung cancer and other diseases.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-015-2097-9) contains supplementary material, which is available to authorized users.