MicroRNAs for the Diagnosis and Management of Malignant Pleural Mesothelioma: A Literature Review

Deciphering signaling pathway interplay via miRNAs in malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is a highly invasive form of lung cancer that adversely affects the pleural and other linings of the lungs. MPM is a very aggressive tumor that often has an advanced stage at diagnosis and a bad prognosis (between 7 and 12 months). When people who have been exposed to asbestos experience pleural effusion and pain that is not explained, MPM should be suspected. After being diagnosed, most MPM patients have a one- to four-year life expectancy. The life expectancy is approximately six months without treatment. Despite the plethora of current molecular investigations, a definitive universal molecular signature has yet to be discovered as the causative factor for the pathogenesis of MPM. MicroRNAs (miRNAs) are known to play a crucial role in the regulation of gene expression at the posttranscriptional level. The association between the expression of these short, non-coding RNAs and several neoplasms, including MPM, has been observed. Although the incidence of MPM is very low, there has been a significant increase in research focused on miRNAs in the past few years. In addition, miRNAs have been found to have a role in various regulatory signaling pathways associated with MPM, such as the Notch signaling network, Wnt/β-catenin, mutation of KRAS, JAK/STAT signaling circuit, protein kinase B (AKT), and Hedgehog signaling pathway. This study provides a comprehensive overview of the existing understanding of the roles of miRNAs in the underlying mechanisms of pathogenic symptoms in MPM, highlighting their potential as viable targets for therapeutic interventions.

Melodic maestros: Unraveling the role of miRNAs in the diagnosis, progression, and drug resistance of malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is a highly lethal form of pleural cancer characterized by a scarcity of effective therapeutic interventions, resulting in unfavorable prognoses for afflicted individuals. Besides, many patients experience substantial consequences from being diagnosed in advanced stages. The available diagnostic, prognostic, and therapeutic options for MPM are restricted in scope. MicroRNAs (miRNAs) are a subset of small, noncoding RNA molecules that exert significant regulatory influence over several cellular processes within cell biology. A wide range of miRNAs have atypical expression patterns in cancer, serving specific functions as either tumor suppressors or oncomiRs. This review aims to collate, epitomize, and analyze the latest scholarly investigations on miRNAs that are believed to be implicated in the dysregulation leading to MPM. miRNAs are also discussed concerning their potential clinical usefulness as diagnostic and prognostic biomarkers for MPM. The future holds promising prospects for enhancing diagnostic, prognostic, and therapeutic modalities for MPM, with miRNAs emerging as a potential trigger for such advancements.

LncRNAs and related molecular basis in malignant pleural mesothelioma: challenges and potential

Malignant pleural mesothelioma (MPM) is a rare but invasive cancer, which mainly arises from mesothelial tissues of pleura, peritoneum and pericardium. Despite significant advances in treatments, the prognosis of MPM patients remains poor, and the 5-year survival rate is less than 10%. Therefore, it is urgent to explore novel therapeutic targets for the treatment of MPM. Growing evidence has indicated that long non-coding RNAs (lncRNAs) potentially could be promising therapeutic targets for numerous cancers. In this regard, lncRNAs might also potentially therapeutic targets for MPM. Recent advances have been made to investigate the molecular basis of MPM. This review first provides a comprehensive overview of roles of lncRNAs in MPM and then discusses the relationship between molecular basis of MPM and MPM-related lncRNAs to implement them as promising therapeutic targets for MPM.

Assessment of miR-103a-3p in leukocytes-No diagnostic benefit in combination with the blood-based biomarkers mesothelin and calretinin for malignant pleural mesothelioma diagnosis

Malignant pleural mesothelioma (MPM) is a cancer associated with asbestos exposure and its diagnosis is challenging due to the moderate sensitivities of the available methods. In this regard, miR-103a-3p was considered to increase the sensitivity of established biomarkers to detect MPM. Its behavior and diagnostic value in the Mexican population has not been previously evaluated. In 108 confirmed MPM cases and 218 controls, almost all formerly exposed to asbestos, we quantified miR-103-3a-3p levels in leukocytes using quantitative Real-Time PCR, together with mesothelin and calretinin measured in plasma by ELISA. Sensitivity and specificity of miR-103-3a-3p alone and in combination with mesothelin and calretinin were determined. Bivariate analysis was performed using Mann-Whitney U test and Spearman correlation. Non-conditional logistic regression models were used to calculate the area under curve (AUC), sensitivity, and specificity for the combination of biomarkers. Mesothelin and calretinin levels were higher among cases, remaining as well among males and participants ≤60 years old (only mesothelin). Significant differences for miR-103a-3p were observed between male cases and controls, whereas significant differences between cases and controls for mesothelin and calretinin were observed in men and women. At 95.5% specificity the individual sensitivity of miR-103a-3p was 4.4% in men, whereas the sensitivity of mesothelin and calretinin was 72.2% and 80.9%, respectively. Positive correlations for miR-103a-3p were observed with age, environmental asbestos exposure, years with diabetes mellitus, and glucose levels, while negative correlations were observed with years of occupational asbestos exposure, creatinine, erythrocytes, direct bilirubin, and leukocytes. The addition of miR-103a-3p to mesothelin and calretinin did not increase the diagnostic performance for MPM diagnosis. However, miR-103a-3p levels were correlated with several characteristics in the Mexican population.

Exploring MicroRNA and Exosome Involvement in Malignant Pleural Mesothelioma Drug Response

Malignant pleural mesothelioma (MPM) is a deadly thoracic malignancy and existing treatment options are limited. Chemotherapy remains the most widely used first-line treatment regimen for patients with unresectable MPM, but is hampered by drug resistance issues. The current study demonstrated a modest enhancement of MPM cell sensitivity to chemotherapy drug treatment following microRNA (miRNA) transfection in MPM cell lines, albeit not for all tested miRNAs. This effect was more pronounced for FAK (PND-1186) small molecule inhibitor treatment; consistent with previously published data. We previously established that MPM response to survivin (YM155) small molecule inhibitor treatment is unrelated to basal survivin expression. Here, we showed that MPM response to YM155 treatment is enhanced following miRNA transfection of YM155-resistant MPM cells. We determined that YM155-resistant MPM cells secrete a higher level of exosomes in comparison to YM155-sensitive MPM cells. Despite this, an exosome inhibitor (GW4896) did not enhance MPM cell sensitivity to YM155. Additionally, our study showed no evidence of a correlation between the mRNA expression of inhibitor of apoptosis (IAP) gene family members and MPM cell sensitivity to YM155. However, two drug transporter genes, ABCA6 and ABCA10, were upregulated in the MPM cell lines and correlated with poor sensitivity to YM155.

Serum Expression Levels of Certain miRNAs in Predicting Diagnosis, Prognosis, and Response to Chemotherapy in Malignant Pleural Mesothelioma

Background:

miRNAs are involved in tumor pathogenesis and can therefore be determined in the primary tumor, plasma and serum, and body fluids. As in various cancers, their role in the diagnosis, prognosis, and treatment of patients with malignant pleural mesothelioma (MPM) may be important.

Aims:

To analyze the predictive value of miR-16-5p, miR-29c-3p, miR-31-5p, miR-125a-5p, miR-320a, miR-484 and miR-532-5p expressions for diagnosis, prognosis and response to treatment in patients with MPM.

Study Design:

Prospective case-control study.

Methods:

In the first phase of the study, blood samples were collected from 101 MPM patients before chemotherapy and from 24 healthy donors (HDs). In the second phase, the blood samples were collected from 74 MPM patients who had received chemotherapy when the best overall response and disease recurrence were determined. A quantitative real-time polymerase chain reaction was undertaken to detect the miRNA expression levels. The miRNA expression profiles of MPM patients were compared with those of HDs. The associations between the expression levels of miRNAs and prognosis and response to treatment were then evaluated.

Results:

All miRNAs, except miR-31-5p, were expressed differently in MPM relative to that in HDs. The expression level of miR-16-5p decreased when compared with that of HDs, and the expression levels of miR-29c-3p, miR-125a-5p, miR-320a, miR-484, and miR-532-5p increased when compared with that of HDs. The sensitivity and specificity values of miR-29c-3p, miR-125a-5p, miR-320a, miR-484, and miR-532-5p for discriminating MPM from HDs were 85.9% and 59.1%, 95.1% and 62.5%, 87.1% and 79.2%, 82.2% and 58.3%, and 69.3% and 82.6%, respectively. After adjusting for the histological subtype, stage, and treatment, the miR-29c-3p, miR-125a-5p, and miR-484 were associated with longer survival. The miRNA expression levels did not change longitudinally for the determination of chemotherapy response and recurrence.

Conclusion:

miRNAs may be useful in diagnosing patients with MPM and provides helpful information in determining the prognosis of patients.

Effects of microRNA-101-3p on predicting pediatric acute respiratory distress syndrome and its role in human alveolar epithelial cell

Pediatric acute respiratory distress syndrome (PARDS) is a severe form of respiratory failure associated with high mortality among children. The objective of this study is reported to explore the clinical function and molecular roles of microRNA-101-3p (miR-101-3p) in PARDS. The levels of miR-101-3p and mRNA levels of SRY-related high-mobility group box 9 (Sox9) were measured by quantitative reverse transcription polymerase chain reaction (RT-qPCR). Additionally, the diagnostic role of miR-101-3p was identified by using the Receiver operating characteristic (ROC) curve. The cell proliferation and apoptosis were examined through Cell Counting Kit-8 (CCK-8) assay and flow cytometry. To detect inflammation in cells, enzyme-linked immunosorbent assays (ELISA) were performed. The target gene of miR-101-3p was confirmed through data obtained from the luciferase activity. In patients with PARDS, miR-101-3p expression was decreased. Moderate and severe PARDS patients had lower levels of miR-101-3p than mild PARDS patients. The inflammatory progression was related to the aberrant expression of miR-101-3p in all PARDS children. MiR-101-3p was highly predictive for the detection of children with PARDS. In addition, miR-101-3p might protect A549 cells from abnormal proliferation, apoptosis, and inflammation caused by lipopolysaccharide (LPS). Sox9 might be a target gene of miR-101-3p and increased mRNA expression of Sox9 in LPS-treated A549 cells was inhibited by overexpression of miR-101-3p. Ultimately, this study suggested that reduced expression of miR-101-3p plays a role in PARDS, providing a novel angle to study the disease.

Bioinformatic Analysis of Potential Biomarker for hsa-miR-196b-5p in Mesothelioma

Purpose: Malignant pleural mesothelioma is a rare neoplasia with a poor prognosis, and the majority of patients have advanced disease at the time of presentation. Exposure to asbestos is the most important risk factor for malignant pleural mesothelioma. Materials and Methods: To determine the cytotoxicity of geldanamycin in mesothelioma H28 cells, the MTT assay was used. To determine changes in microRNA (miRNA) expression in geldanamycin-treated H28 cells, miRNA microarray analysis was performed. To determine the function of miR-196b-5p, we performed Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses of miR-196b-5p targets predicted by miRwalk. Results: Our data showed that geldanamycin treatment reduced H28 cell viability in a dose-dependent manner. MicroRNA array analyses showed that expression of hsa-miR-196b-5p was downregulated in geldanamycin-treated H28 cells. Geldanamycin regulated miRNAs with roles in processes such as aging, angiogenesis, apoptosis, cell cycle, cell differentiation, cell proliferation, DNA repair, and secretion. Survival analysis showed that decreased expression of hsa-miR-196b-5p was significantly associated with a better outcome in mesothelioma patients. Expression of miR-196b-5p was also significantly associated with the developmental stages of mesothelioma. To narrow down the target genes of miR-196b-5p, we determined the overlap between the predicted target genes of miR-196b-5p and downregulated mRNAs in ovarian cancer based on the Gene Expression Omnibus dataset GSE12345. PDE1A, LAMA4, and PAPPA were identified as both miR-196b-5p targets and downregulated genes in GSE12345 and were thus considered targets of miR-196b-5p. Gene-miRNA expression correlation analysis showed that PDE1A, LAMA4, and PAPPA expression was negatively correlated with miR-196b-5p expression. Conclusions: We suggest that geldanamycin has potential for the treatment of mesothelioma via regulating miR-196b-5p. Furthermore, miR-196b-5p may be a potential biomarker for mesothelioma.

Extracellular Vesicle Enriched miR-625-3p Is Associated with Survival of Malignant Mesothelioma Patients

Malignant mesothelioma (MM) is characterized by poor prognosis and short survival. Extracellular vesicles (EVs) are membrane-bound particles released from cells into various body fluids, and their molecular composition reflects the characteristics of the origin cell. Blood EVs or their miRNA cargo might serve as new minimally invasive biomarkers that would enable earlier detection of MM or treatment outcome prediction. Our aim was to evaluate miRNAs enriched in serum EVs as potential prognostic biomarkers in MM patients in a pilot longitudinal study. EVs were isolated from serum samples obtained before and after treatment using ultracentrifugation on 20% sucrose cushion. Serum EV-enriched miR-103-3p, miR-126-3p and miR-625-3p were quantified using qPCR. After treatment, expression of miR-625-3p and miR-126-3p significantly increased in MM patients with poor treatment outcome (p = 0.012 and p = 0.036, respectively). A relative increase in miR-625-3p expression after treatment for more than 3.2% was associated with shorter progression-free survival (7.5 vs. 19.4 months, HR = 3.92, 95% CI = 1.20-12.80, p = 0.024) and overall survival (12.5 vs. 49.1 months, HR = 5.45, 95% CI = 1.06-28.11, p = 0.043) of MM patients. Bioinformatic analysis showed enrichment of 33 miR-625-3p targets in eight biological pathways. Serum EV-enriched miR-625-3p could therefore serve as a prognostic biomarker in MM and could contribute to a more personalized treatment.

Inhibition of miR-214-3p Protects Endothelial Cells from ox-LDL-Induced Damage by Targeting GPX4

It is generally believed that excessive production of reactive oxygen species (ROS) during cardiovascular diseases impairs endothelial function. In this study, we aimed to investigate whether miR-214-3p is involved in the endothelial dysfunction induced by oxidized low-density lipoprotein (ox-LDL). In cultured vascular endothelial cells (VECs), the effects of miR-214-3p on endothelial injury induced by 100 mg/L ox-LDL were evaluated by knockdown of miR-214-3p. Western blotting was used to determine the expression of glutathione peroxidase 4 (GPX4) and endothelial nitric oxide synthase (eNOS) in VECs under different conditions. A luciferase reporter assay was used to identify GPX4 as the target of miR-214-3p. Our data showed that 100 mg/L ox-LDL significantly decreased the expression of GPX4 and eNOS, which was associated with increases in ROS levels and impairments of VEC viability and migration. Knockdown of miR-214-3p could partially reduce the increase in ROS, restore the decreased expression of GPX4 and eNOS, and thus rescue the impaired endothelial function caused by ox-LDL. Our data demonstrated that ox-LDL could induce upregulation of miR-214-3p and result in suppression of GPX4 in VECs. Downregulation of miR-214-3p could protect VECs from ROS-induced endothelial dysfunction by reversing its inhibitory effect on GPX4 expression.

Overexpression of microRNA‑486 affects the proliferation and chemosensitivity of mesothelioma cell lines by targeting PIM1

Dysregulated levels of microRNAs (miRNAs or miRs), involved in oncogenic pathways, have been proposed to contribute to the aggressiveness of malignant pleural mesothelioma (MPM). Previous studies have highlighted the downregulation of miRNA miR-486-5p in patients with mesothelioma and the introduction of miRNA mimics to restore their reduced or absent functionality in cancer cells is considered an important therapeutic strategy. The aim of the present study was to evaluate the mechanisms through which miRNAs may influence the functions, proliferation and sensitivity to cisplatin of MPM cells. In the present study, a miR-486-5p mimic was transfected into the H2052 and H28 MPM cell lines, and cell viability, proliferation, apoptosis and mitochondrial membrane potential were monitored. miR-486-5p overexpression led to a clear impairment of cell proliferation, targeting CDK4 and attenuating cell cycle progression. In addition, transfection with miR-486-5p mimic negatively regulated the release of inflammatory factors and the expression of Provirus integration site for Moloney murine leukaemia virus 1 (PIM1). The sensitivity of the cells to cisplatin was enhanced by enhancing the apoptotic effects of the drug and impairing mitochondrial function. On the whole, the present study demonstrates that miR-486-5p may play an important role in MPM treatment by targeting multiple pathways involved in tumour development and progression. These activities may be mostly related to the downregulation of PIM1, a crucial regulator of cell survival and proliferation. Furthermore, these results provide support for the combined use of miR-486-5p with chemotherapy as a therapeutic strategy for MPM.

Micro-RNA 122 and micro-RNA 96 affected human osteosarcoma biological behavior and associated with prognosis of patients with osteosarcoma

Osteosarcoma (OS) is the most common bone malignancy in both children and adolescents. In the present study, we aimed to explore the association of miRNA-122 and miRNA-96 expression with the clinical characteristics and prognosis of patients with osteosarcoma. The expression of miRNA-122 and miRNA-96 in human osteosarcoma cell lines and tissues were detected in the present study. Reverse transcriptase-PCR (RT-PCR) was used to determine the expression levels of miRNA-122 and miRNA-96 in 68 human OS samples. We found that MiRNA-122 and miRNA-96 were widely up-regulated in osteosarcoma, gastric cancer and pancreatic cancer. In HOS, Saos-2 and U2OS osteosarcoma cells, miRNA-122 and miRNA-96 were up-regulated significantly, while down-regulated in MG-63 cells. After further investigation, we found that miRNA-122 and miRNA-96 concentrations were significantly higher in the tumor tissues than those in the normal tissues (P<0.01). Moreover, the cell proliferation of LV-miRNA-122-RNAi and LV-miRNA-96-RNAi transfected SaOS2 was significantly decreased compared with the LV- miRNA-122-RNAi-CN and LV- miRNA-96-RNAi group. After adjusting for competing risk factors, we found combined high miRNA-122 and miRNA-96 expression was identified as independent predictor of overall survival.

The Evolving Landscape of the Molecular Epidemiology of Malignant Pleural Mesothelioma

Malignant pleural mesothelioma (MPM) is a rare and aggressive malignancy that most commonly affects the pleural lining of the lungs. It has a strong association with exposure to biopersistent fibers, mainly asbestos (80% of cases) and—in specific geographic regions—erionite, zeolites, ophiolites, and fluoro-edenite. Individuals with a chronic exposure to asbestos generally have a long latency with no or few symptoms. Then, when patients do become symptomatic, they present with advanced disease and a worse overall survival (about 13/15 months). The fibers from industrial production not only pose a substantial risk to workers, but also to their relatives and to the surrounding community. Modern targeted therapies that have shown benefit in other human tumors have thus far failed in MPM. Overall, MPM has been listed as orphan disease by the European Union. However, molecular high-throughput profiling is currently unveiling novel biomarkers and actionable targets. We here discuss the natural evolution, mainly focusing on the novel concept of molecular epidemiology. The application of innovative endpoints, quantification of genetic damages, and definition of genetic susceptibility are reviewed, with the ultimate goal to point out new tools for screening of exposed subject and for designing more efficient diagnostic and therapeutic strategies.

Diagnostic mesothelioma biomarkers in effusion cytology

Malignant mesothelioma is a rare malignancy with a poor prognosis whose development is related to asbestos fiber exposure. An increasing role of genetic predisposition has been recognized recently. Pleural biopsy is the gold standard for diagnosis, in which the identification of pleural invasion by atypical mesothelial cell is a major criterion. Pleural effusion is usually the first sign of disease; therefore, a cytological specimen is often the initial or the only specimen available for diagnosis. Given that reactive mesothelial cells may show marked atypia, the diagnosis of mesothelioma on cytomorphology alone is challenging. Accordingly, cell block preparation is encouraged, as it permits immunohistochemical staining. Traditional markers of mesothelioma such as glucose transporter 1 (GLUT1) and insulin-like growth factor 2 mRNA-binding protein 3 (IMP3) are informative, but difficult to interpret when reactive proliferations aberrantly stain positive. BRCA1-associated protein 1 (BAP1) nuclear staining loss is highly specific for mesothelioma, but sensitivity is low in sarcomatoid tumors. Cyclin-dependent kinase inhibitor 2A (CDKN2A)/p16 homozygous deletion, assessed by fluorescence in situ hybridization, is more specific for mesothelioma with better sensitivity, even in the sarcomatoid variant. The surrogate marker methylthioadenosine phosphorylase (MTAP) has been found to demonstrate excellent diagnostic correlation with p16. The purpose of this review is to provide an essential appraisal of the literature regarding the diagnostic value of many of these emerging biomarkers for malignant mesothelioma in effusion cytology.

Potential role of serum mesothelin in predicting survival of patients with malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is an aggressive tumor with poor survival rates. Therefore, it is essential to have effective biological markers predicting the course of the disease and prognosis. The aim of the present study was to highlight the prognostic significance of serum soluble mesothelin-related protein (Se-SMRP) in patients with MPM at diagnosis. Se-SMRP was determined in 60 patients using an ELISA commercial kit. Se-SMRP levels were subdivided into three tertile-based categories and in each category overall survival (OS) indexes were determined using the Kaplan-Meier and Cox regression analyses. The association between Se-SMRP levels and OS was also assessed by restricted cubic spline (RCS) analysis. No notable differences in the Kaplan-Meier probabilities were identified across the Se-SMRP categories (<0.66 nM, 0.66-1.46 nM, >1.46 nM) although an upward trend in death rate ratios (RR) was pointed out by comparing the higher (RR=1.95) and intermediate (RR=1.86) categories with the lower category (RR=1.00). In addition, such an increasing tendency, particularly when the biomarker exceeded 1.0 nM, was confirmed by an RCS function of Se-SMPR levels fitted to survival data using the Cox regression equation. The present study provided evidence in favor of a prognostic value of Se-SMRP in patients with MPM.

Epigenetic Alterations and Biomarkers for Immune Checkpoint Inhibitors-Current Standards and Future Perspectives in Malignant Pleural Mesothelioma Treatment

Malignant pleural mesothelioma (MPM) is strongly associated with occupational or environmental asbestos exposure and arises from neoplastic transformation of mesothelial cells in the pleural cavity. The only standard initial treatment for unresectable MPM is combination chemotherapy with cisplatin (CDDP) and pemetrexed (PEM). Further, CDDP/PEM is the only approved regimen with evidence of prolonged overall survival (OS), although the median OS for patients treated with this regimen is only 12 months after diagnosis. Thus, the development of new therapeutic strategies has been investigated for approximately 20 years. In contrast to recent advances in personalized lung cancer therapies, diagnostic and prognostic biomarker research has just started in mesothelioma. Epigenetic alterations include DNA methylation, histone modifications, and other chromatin-remodeling events. These processes are involved in numerous cellular processes including differentiation, development, and tumorigenesis. Epigenetic modifications play an important role in gene expression and regulation related to malignant MPM phenotypes and histological subtypes. An immune checkpoint PD-1 inhibitor, nivolumab, was approved as second-line therapy for patients who had failed initial chemotherapy, based on the results of the MERIT study. Various clinical immunotherapy trials are ongoing in patients with advanced MPM. In this review, we describe recent knowledge on epigenetic alterations, which might identify candidate therapeutic targets and immunotherapeutic regimens under development for MPM.

A comparison between the effects of over-expression of miRNA-16 and miRNA-34a on cell cycle progression of mesothelioma cell lines and on their cisplatin sensitivity

The prognosis of patients affected by malignant pleural mesothelioma (MPM) is presently poor and no therapeutic strategies have improved their survival yet. Introduction of miRNA mimics to restore their reduced or absent functionality in cancer cells is considered an important opportunity and a combination of miR's might be even more effective. In the present study, miR-16 and miR-34a were transfected, singularly and in combination, in MPM cell lines H2052 and H28, and their effects on cell proliferation and sensitivity to cisplatin are reported. Interestingly, the overexpression of both miRs, alone or combined, slows down the cell cycle progression, modulates the p53 and HMGB1 expression and increases the sensitivity of cells to cisplatin, producing a marked impairment of cell proliferation and strengthening the apoptotic effect of the drug. However, the co-overexpression of the two miRs results more effective only in the regulation of the cell cycle, but does not enhance the sensitivity of MPM cells to cisplatin. Consequently, although the potential of miR-16 and miR-34a is confirmed, we must conclude that their combination does not improve the response of MPM to chemotherapy.

Circulating biomarkers in malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is an aggressive tumor strictly connected to asbestos exposure. Prognosis is dismal as diagnosis commonly occurs in advanced stage. Radiological screenings have not proven to be effective and also pathological diagnosis may be challenging. In the era of precision oncology, validation of robust non-invasive biomarkers for screening of asbestos-exposed individuals, assessment of prognosis and prediction of response to treatments remains an important unmet clinical need. This review provides an overview on current understanding and possible applications of liquid biopsy in MPM, mostly focused on the utility as diagnostic and prognostic test.

The influence of genetic variability in IL1B and MIR146A on the risk of pleural plaques and malignant mesothelioma

Background

Asbestos exposure is associated with the development of pleural plaques as well as malignant mesothelioma (MM). Asbestos fibres activate macrophages, leading to the release of inflammatory mediators including interleukin 1 beta (IL-1β). The expression of IL-1β may be influenced by genetic variability of IL1B gene or regulatory microRNAs (miRNAs). This study investigated the effect of polymorphisms in IL1B and MIR146A genes on the risk of developing pleural plaques and MM.

Subjects and methods

In total, 394 patients with pleural plaques, 277 patients with MM, and 175 healthy control subjects were genotyped for IL1B and MIR146A polymorphisms. Logistic regression was used in statistical analysis.

Results

We found no association between MIR146A and IL1B genotypes, and the risk of pleural plaques. MIR146A rs2910164 was significantly associated with a decreased risk of MM (OR = 0.31, 95% CI = 0.13–0.73, p = 0.008). Carriers of two polymorphic alleles had a lower risk of developing MM, even after adjustment for gender and age (OR = 0.34, 95% CI = 0.14–0.85, p = 0.020). Among patients with known asbestos exposure, carriers of at least one polymorphic IL1B rs1143623 allele also had a lower risk of MM in multivariable analysis (OR = 0.50, 95% CI = 0.28–0.92, p = 0.025). The interaction between IL1B rs1143623 and IL1B rs1071676 was significantly associated with an increased risk of MM (p = 0.050).

Conclusions

Our findings suggest that genetic variability of inflammatory mediator IL-1β could contribute to the risk of developing MM, but not pleural plaques.

MicroRNA (MiR)-301a-3p regulates the proliferation of esophageal squamous cells via targeting PTEN

Human esophageal carcinoma (EC) is a common cancer, which leads to many deaths worldwide every year. Our study aimed to explore the mechanism of miR-301a-3p regulating the proliferation of esophageal squamous cell carcinoma (ESCC) cells. We had collected ESCC tissues and adjacent normal esophageal tissues from 47 patients. The relative levels of miR-301a-3p/U6 in ESCC tissues and cells were analyzed by real-time PCR. And we measured the relative protein levels of PTEN, BCL-2, BAX, and p-AKT/AKT by Western blot. Eca-109 cell proliferation was detected by MTT assay and colony formation. Compared with adjacent normal esophageal tissues, the relative level of miR-301a-3p/U6 was elevated in ESCC tissues. MiR-301a-3p could facilitate ESCC cell proliferation. And miR-301a-3p directly bind to PTEN 3ʹ-UTR and negatively regulated PTEN protein expression. Moreover, silencing PTEN could reversed inhibited proliferation of Eca-109 cells induced by miR-301a-3p inhibitor, while overexpression PTEN could reversed enhanced proliferation of Eca-109 cells induced by miR-301a-3p mimic. Taken together, miR-301a-3p promoted ESCC cell proliferation by supressing PTEN.

P53-regulated miR-320a targets PDL1 and is downregulated in malignant mesothelioma

Malignant pleural mesothelioma (MPM) is an aggressive cancer, related to asbestos exposure, which has a dismal prognosis. MPM diagnosis is late and often challenging, suggesting the need to identify more reliable molecular biomarkers. Here, we set out to identify differentially expressed miRNAs in epithelioid, biphasic, and sarcomatoid MPMs versus normal mesothelium and explored specific miRNA contribution to mesothelial tumorigenesis. We screened an LNA™-based miRNA-microrray with 14 formalin-fixed paraffin-embedded (FFPE) MPMs and 6 normal controls. Through real-time qRT-PCR we extended the analysis of a miRNA subset and further investigated miR-320a role through state-of-the-art techniques. We identified 16 upregulated and 32 downregulated miRNAs in MPMs versus normal tissue, including the previously identified potential biomarkers miR-21, miR-126, miR-143, miR-145. We showed in an extended series that miR-145, miR-10b, and miR-320a levels can discriminate tumor versus controls with high specificity and sensitivity. We focused on miR-320a because other family members were found downregulated in MPMs. However, stable miR-320a ectopic expression induced higher proliferation and migration ability, whereas miR-320a silencing reduced these processes, not supporting a classic tumor-suppressor role in MPM cell lines. Among putative targets, we found that miR-320a binds the 3'-UTR of the immune inhibitory receptor ligand PDL1 and, consistently, miR-320a modulation affects PDL1 levels in MPM cells. Finally, we showed that p53 over-expression induces the upregulation of miR-320a, along with miR-200a and miR-34a, both known to target PDL1, and reduces PDL1 levels in MPM cells. Our data suggest that PDL1 expression might be due to a defective p53-regulated miRNA response, which could contribute to MPM immune evasion or tumorigenesis through tumor-intrinsic roles.

Mesothelioma Biomarkers: Discovery in Search of Validation

Malignant pleural mesothelioma (MPM) is an asbestos-related neoplasm that can only be treated successfully when correctly diagnosed and treated early. The asbestos-exposed population is a high-risk group that could benefit from sensitive and specific blood- or tissue-based biomarkers. We review recent work with biomarker development in MPM and literature of the last 20 years on the most promising blood- and tissue-based biomarkers. Proteomic, genomic, and epigenomic platforms are covered. SMRP is the only validated blood-based biomarker with diagnostic, monitoring and prognostic value. To strengthen development and testing of MPM biomarkers, cohorts for validation must be established by enlisting worldwide collaborations.

The Use of Immunohistochemistry, Fluorescence in situ Hybridization, and Emerging Epigenetic Markers in the Diagnosis of Malignant Pleural Mesothelioma (MPM): A Review

Malignant pleural mesothelioma (MPM) is an aggressive asbestos related disease that is generally considered to be difficult to diagnose, stage and treat. The diagnostic process is continuing to evolve and requires highly skilled pathology input, and generally an extensive list of biomarkers for definitive diagnosis. Diagnosis of MPM requires histological evidence of invasion by malignant mesothelial cells often confirmed by various immunohistochemical biomarkers in order to separate it from pleural metastatic carcinoma. Often when invasion of neoplastic mesothelial cells into adjacent tissue is not apparent, further immunohistochemical testing - namely BAP1 and MTAP, as well as FISH testing for loss of p16 (CDKN2A) are used to separate reactive mesothelial proliferation due to benign processes, from MPM. Various combinations of these markers, such as BAP1 and/or MTAP immunohistochemistry alongside FISH testing for loss of p16, have shown excellent sensitivity and specificity in the diagnosis of MPM. Additionally, over the recent years, research into epigenetic marker use in the diagnosis of MPM has gained momentum. Although still in their research stages, various markers in DNA methylation, long non-coding RNA, micro RNA, circular RNA, and histone modifications have all been found to support diagnosis of MPM with generally good sensitivity and specificity. Many of these studies are however, limited by small sample sizes or other study limitations and further research into the area would be beneficial. Epigenetic markers show promise for use in the future to facilitate the diagnosis of MPM.

Multiplex Soluble Biomarker Analysis from Pleural Effusion

Malignant pleural mesothelioma (MPM) is a highly aggressive and therapy resistant pleural malignancy that is caused by asbestos exposure. MPM is associated with poor prognosis and a short patient survival. The survival time is strongly influenced by the subtype of the tumor. Dyspnea and accumulation of pleural effusion in the pleural cavity are common symptoms of MPM. The diagnostic distinction from other malignancies and reactive conditions is done using histopathology or cytopathology, always supported by immunohistochemistry, and sometimes also by analyses of soluble biomarkers in effusion supernatant. We evaluated the soluble angiogenesis related molecules as possible prognostic and diagnostic biomarkers for MPM by Luminex multiplex assay. Pleural effusion from 42 patients with malignant pleural mesothelioma (MPM), 36 patients with adenocarcinoma (AD) and 40 benign (BE) effusions were analyzed for 10 different analytes that, in previous studies, were associated with angiogenesis, consisting of Angiopoietin-1, HGF, MMP-7, Osteopontin, TIMP-1, Galectin, Mesothelin, NRG1-b1, Syndecan-1 (SDC-1) and VEGF by a Human Premixed Multi-Analyte Luminex kit. We found that shed SDC-1 and MMP-7 levels were significantly lower, whereas Mesothelin and Galectin-1 levels were significantly higher in malignant mesothelioma effusions, compared to adenocarcinoma. Galectin-1, HGF, Mesothelin, MMP-7, Osteopontin, shed SDC-1, NRG1-β1, VEGF and TIMP-1 were significantly higher in malignant pleural mesothelioma effusions compared to benign samples. Moreover, there is a negative correlation between Mesothelin and shed SDC-1 and positive correlation between VEGF, Angiopoietin-1 and shed SDC-1 level in the pleural effusion from malignant cases. Shed SDC-1 and VEGF have a prognostic value in malignant mesothelioma patients. Collectively, our data suggest that MMP-7, shed SDC-1, Mesothelin and Galectin-1 can be diagnostic and VEGF and SDC-1 prognostic markers in MPM patients. Additionally, Galectin-1, HGF, Mesothelin, MMP-7, Osteopontin, shed SDC-1 and TIMP-1 can be diagnostic for malignant cases.

Mesothelioma Biomarkers: A Review Highlighting Contributions from the Early Detection Research Network

Malignant pleural mesothelioma (MPM) is an asbestos-related neoplasm, which can be treated successfully only if correctly diagnosed and treated in early stages. The asbestos-exposed population serves as a high-risk group that could benefit from sensitive and specific blood- or tissue-based biomarkers. This review details the recent work with biomarker development in MPM and the contributions of the NCI Early Detection Research Network Biomarker Developmental Laboratory of NYU Langone Medical Center. The literature of the last 20 years was reviewed to comment on the most promising of the blood- and tissue-based biomarkers. Proteomic, genomic, and epigenomic platforms as well as novel studies such as "breath testing" are covered. Soluble mesothelin-related proteins (SMRP) have been characterized extensively and constitute an FDA-approved biomarker in plasma with diagnostic, monitoring, and prognostic value in MPM. Osteopontin is found to be a valuable prognostic biomarker for MPM, while its utility in diagnosis is slightly lower. Other biomarkers, such as calretinin, fibulin 3, and High-Mobility Group Box 1 (HMGB1), remain under study and need international validation trials with large cohorts of cases and controls to demonstrate any utility. The EDRN has played a key role in the development and testing of MPM biomarkers by enlisting collaborations all over the world. A comprehensive understanding of previously investigated biomarkers and their utility in screening and early diagnosis of MPM will provide guidance for further future research.See all articles in this CEBP Focus section, "NCI Early Detection Research Network: Making Cancer Detection Possible."

Overexpression of miR-199/214 is a distinctive feature of iron-induced and asbestos-induced sarcomatoid mesothelioma in rats

Malignant mesothelioma (MM) is one of the most lethal tumors in humans. The onset of MM is linked to exposure to asbestos, which generates reactive oxygen species (ROS). ROS are believed to be derived from the frustrated phagocytosis and the iron in asbestos. To explore the pathogenesis of MM, peritoneal MM was induced in rats by the repeated intraperitoneal injection of iron saccharate and nitrilotriacetate. In the present study, we used microarray techniques to screen the microRNA (miR) expression profiles of these MM. We observed that the histological subtype impacted the hierarchical clustering of miR expression profiles and determined that miR-199/214 is a distinctive feature of iron saccharate-induced sarcomatoid mesothelioma (SM). Twist1, a transcriptional regulator of the epithelial-mesenchymal transition, has been shown to activate miR-199/214 transcription; thus, the expression level of Twist1 was examined in iron-induced and asbestos-induced mesotheliomas in rats. Twist1 was exclusively expressed in iron saccharate-induced SM but not in the epithelioid subtype. The Twist1-miR-199/214 axis is activated in iron saccharate-induced and asbestos-induced SM. The expression levels of miR-214 and Twist1 were correlated in an asbestos-induced MM cell line, suggesting that the Twist1-miR-199/214 axis is preserved. MeT5A, an immortalized human mesothelial cell line, was used for the functional analysis of miR. The overexpression of miR-199/214 promoted cellular proliferation, mobility and phosphorylation of Akt and ERK in MeT5A cells. These results indicate that miR-199/214 may affect the aggressive biological behavior of SM.

HEG1-responsive microRNA-23b regulates cell proliferation in malignant mesothelioma cells

Malignant mesothelioma (MM) is a fatal tumor, and the absence of a specific diagnostic marker and/or a pathogenic molecule-targeting drug is a major issue for its pathological diagnosis and for targeting therapy. The molecular target of MM has not been elucidated because of unknown survival, death, and cytotoxic signals in MM. HEG homolog 1 (HEG1) is a mucin-like membrane protein that contains epidermal growth factor-like domains, and it plays an important role in cancers through aberrant signaling, including that during cell adhesion, as well as through protection from invasion of tumor cells. HEG1 expression supports the survival and proliferation of MM cells. In this study, functional analysis of HEG1 and microRNAs using MM cell lines (H226, MESO4, H2052) was performed. The MTS assay revealed that cell proliferation was significantly reduced upon transient transfection with microRNA-23b (miR-23b) inhibitor and/or HEG1 siRNA. The Annexin V assay revealed that apoptosis was induced upon suppression of miR-23b and/or HEG1. Western blotting showed that the autophagy-related protein LC3-II was induced upon suppression of miR-23b and/or HEG1. These results revealed that miR-23b contributes to HEG1-dependent cell proliferation through evasion of cytotoxicity induced by apoptosis and autophagy in MM cells. HEG1-dependent/mediated miR-23b signaling may therefore be a potential target for MM diagnosis and therapy.

Extracellular vesicles as biomarkers in malignant pleural mesothelioma: A review

Extracellular vesicles (EV) are secreted by all cells, including cancer cells, as a mode of intercellular transport and communication. The main types of EV known to date include exosomes, microvesicles and apoptotic bodies, as well as oncosomes and large oncosomes, which are specific to cancer cells. These different EV populations carry specific cargo from one cell to another to stimulate a specific response. They can be found in all body fluids and can be detected in liquid biopsies. EV released from mesothelioma cells can reveal important information about the molecules and signalling pathways involved in the development and progression of the tumour. The presence of tumour-derived EV in circulating body fluids makes them potential novel biomarkers for early diagnosis, prognostication and surveillance of cancer. In this review, we explore the characteristics and functional roles of EV reported in the literature, with a focus on their role in malignant pleural mesothelioma.

Inhibition of miR-18a-3p reduces proliferation of mesothelioma cells and sensitizes them to cisplatin

Malignant pleural mesothelioma is a notorious human malignancy. Despite combination chemotherapy with cisplatin and pemetrexed, the majority of patients with advanced malignant pleural mesothelioma have a poor prognosis. MicroRNAs (miRNAs/miRs) are short non-coding RNAs that regulate various biological processes by binding to the 3'-untranslated region of target gene mRNAs and suppressing their expression. Since abnormal expression patterns of miRNAs are a common feature in human malignancies, a number of them have been researched as potential therapeutic targets. Our previous study demonstrated that microRNA-18a (miR-18a) is upregulated in mesothelioma cell lines compared with in non-neoplastic mesothelial tissues, but its function remains unclear. In the present study, miRNA inhibitor was transfected into mesothelioma cell lines and then analyzed various cellular functions. Mesothelioma cells transfected with the miR-18a inhibitor exhibited lower proliferation and migration rates compared with cells transfected with a negative control inhibitor in proliferation and wound scratch assays, respectively. Additionally, the present study revealed that downregulation of miR-18a increased mesothelioma cell apoptosis. In a chemosensitivity assay, transfection of the miR-18a inhibitor significantly increased the sensitivity of mesothelioma cells to cisplatin but not to pemetrexed. Therefore, miR-18a may be a potential therapeutic target for mesothelioma resistant to cisplatin.

Epigenetic Regulation of miRNA Expression in Malignant Mesothelioma: miRNAs as Biomarkers of Early Diagnosis and Therapy

Asbestos exposure leads to epigenetic and epigenomic modifications that, in association with ROS-induced DNA damage, contribute to cancer onset. Few miRNAs epigenetically regulated in MM have been described in literature; miR-126, however, is one of them, and its expression is regulated by epigenetic mechanisms. Asbestos exposure induces early changes in the miRNAs, which are reversibly expressed as protective species, and their inability to reverse reflects the inability of the cells to restore the physiological miRNA levels despite the cessation of carcinogen exposure. Changes in miRNA expression, which results from genetic/epigenetic changes during tumor formation and evolution, can be detected in fluids and used as cancer biomarkers. This article has reviewed the epigenetic mechanisms involved in miRNA expression in MM, focusing on their role as biomarkers of early diagnosis and therapeutic effects.

MicroRNAs - novel biomarkers for malignant pleural effusions

Lung cancer is one of the most common causes of cancer death. Its poor prognosis can be attributed to the patients’ advanced or metastatic presentation at the time of diagnosis. To improve and accelerate the diagnosis, better therapeutic and diagnostic methods are constantly being sought. MicroRNAs (miRNAs) are short nucleotide sequences of single-stranded, non-coding RNA that function as critical post-transcriptional regulators of gene expression. They are identified not only intracellularly, but also in physiological and pathological body fluids. These molecules are responsible for the regulation of approximately 33% of human genes, either regulating the expression of both oncogenes and suppressor genes or acting directly as an oncogene or suppressor gene itself. MiRNAs can contribute to the formation of cancer. The high specificity and sensitivity of miRNAs have been demonstrated with various malignant diseases, and for this reason, they raise particular interest as new and perspective biomarkers of tumours. Our work summarises the available information from recent years regarding the possibility of using miRNAs as biomarkers in the diagnosis of neoplasms. In this review, we focused on malignant pleural effusions with an emphasis on non-small cell lung cancer (NSCLC).

[MicroRNA-152 and microRNA-448 inhibit proliferation of colorectal cancer cells in vitro by targeting Rictor]

OBJECTIVE

To screen the microRNAs (miRNAs) targeting Rictor and investigate their effects in regulating the biological behaviors of colorectal cancer (CRC).

METHODS

Human colorectal cancer cell line KM12SM was transfected with the miRNAs targeting Rictor identified by prediction software to test inhibitory effects of these miRNAs on Rictor expression using qRT-PCR and Western blotting. Dual luciferase reporter assay was used to further confirm the binding of these miRNAs to the 3'UTR of Rictor mRNA. Cell survival and colony formation assays were used to investigate the effects of these miRNAs on survival and colony formation in KM12SM cells.

RESULTS

miR-152 and miR-448 were identified as the Rictor-targeting miRNAs, which significantly inhibited the expression of Rictor in KM12SM cells (P &lt; 0.05). The two miRNAs were confirmed to bind to the 3'UTR of Rictor mRNA and significantly inhibited luciferase activity in KM12SM cells (P &lt; 0.01, P &lt; 0.05); they also showed activities of posttranscriptional modulation of Rictor. Overexpression of miR-152 and miR-448 both significantly inhibited the growth and colony formation of KM12SM cells.

CONCLUSIONS

miR-152 and miR-448 can down-regulate the protein expression of Rictor by targeting Rictor mRNA to negatively regulate the growth and colony formation of colorectal cancer cells.

MicroRNA-300 inhibits the growth of hepatocellular carcinoma cells by downregulating CREPT/Wnt/β-catenin signaling

A number of studies have demonstrated that altered expression levels of microRNA-300 (miR-300) are associated with tumor progression; however, little is understood regarding the role of miR-300 in hepatocellular carcinoma (HCC). The present study aimed to investigate the expression, biological function and potential regulatory mechanism of miR-300 in HCC. A miR-300 mimic and miR-300 inhibitor were transfected into liver cancer cells using RNAiMAX reagent. The expression levels of miR and mRNA were detected by reverse transcription-quantitative polymerase chain reaction. Protein expression levels were detected by western blot analysis. Cell growth was determined using Cell Counting Kit-8, a colony formation assay and cell cycle assay. miRNA targeting sites were analyzed using bioinformatics analysis and dual-luciferase reporter assay. The results revealed that miR-300 expression was significantly decreased in HCC tissues and cell lines. In vitro experiments demonstrated that overexpression of miR-300 could inhibit cell proliferation, colony formation and cell cycle progression of liver cancer cells. By contrast, inhibition of miR-300 was associated with increased rates of cell proliferation, colony formation and cell cycle progression. Notably, regulation of nuclear pre-mRNA domain-containing protein 1B (CREPT) was identified as a putative target gene of miR-300 by bioinformatics analysis. A luciferase reporter assay revealed that miR-300 directly targets the 3′-untranslated region of CREPT. Further data demonstrated that miR-300 can regulate CREPT expression levels in liver cancer cells. Notably, miR-300 was identified to regulate the Wnt/β-catenin signaling pathway in liver cancer cells. The restoration of CREPT expression partially reversed the antitumor effect of miR-300. In conclusion, the current results revealed a tumor suppressive role of miR-300 in HCC and indicated that the underlying mechanism was associated with a regulation of CREPT. The present study suggests that miR-300 and CREPT may serve as potential therapeutic targets for liver cancer.

Downregulation of microRNA‑629‑5p in colorectal cancer and prevention of the malignant phenotype by direct targeting of low‑density lipoprotein receptor‑related protein 6

Aberrant expression of numerous microRNAs (miRNAs/miRs) in colorectal cancer (CRC) significantly affects disease progression. Recently, miR‑629‑5p (miR‑629) was identified as a tumor‑promoting miRNA in the malignant processes of a number of human cancers. However, few studies have been conducted regarding expression profiles and detailed roles of miR‑629 in CRC. In the present study, reverse transcription‑quantitative polymerase chain reaction was used to assess miR‑629 expression in CRC tissues and cell lines. Cell Counting Kit‑8 assay, flow cytometry and Transwell assays were performed to determine the in vitro effects of miR‑629 on CRC cell proliferation, apoptosis, and metastasis, respectively. Xenograft models were employed to determine the in vivo effects of miR‑629 on tumor growth in nude mice. Molecular mechanisms underlying the activity of miR‑629 in CRC cells were explored. miR‑629 expression decreased in CRC tissues and cell lines. The decreased aberrant miR‑629 expression was significantly associated with tumor size, lymphatic metastasis and tumor‑node‑metastasis stage of CRC, and was a predictor of poor prognosis. Restoring miR‑629 expression attenuated CRC cell proliferation, migration and invasion; promoted cell apoptosis in vitro; and inhibited tumor growth in vivo. Low‑density lipoprotein receptor‑related protein 6 (LRP6) was a direct target gene of miR‑629 in CRC cells. Furthermore, the effect of LRP6 knockdown was similar to that of miR‑629 overexpression in CRC cells. Restoration of LRP6 expression neutralized the effects of miR‑629 in CRC cells. miR‑629 suppressed the activation of the Wnt/β‑catenin pathway through LRP6 regulation both in vitro and in vivo. In conclusion, miR‑629 suppressed the development and progression of CRC by directly targeting LRP6 and inhibiting the Wnt/β‑catenin pathway both in vitro and in vivo. Therefore, miR‑629 may be a novel prognostic biomarker and therapeutic target in CRC.

miR-186 Suppresses the Progression of Cholangiocarcinoma Cells Through Inhibition of Twist1

Deregulation of miR-186 and Twist1 has been identified to be involved in the progression of multiple cancers. However, the detailed molecular mechanisms underlying miR-186-involved cholangiocarcinoma (CCA) are still unknown. In this study, we found that miR-186 was downregulated in CCA tissues and cell lines, and negatively correlated with the expression of Twist1 protein. In vitro assays demonstrated that miR-186 mimics repressed cell proliferation, in vivo tumor formation, and caused cell cycle arrest. miR-186 mimics also inhibited the migration and invasion of CCLP1 and SG-231 cells. Mechanistically, the 3′-untranslated region (3′-UTR) of Twist1 mRNA is a direct target of miR-186. Further, miR-186 inhibited the expressions of Twist1, N-cadherin, vimentin, and matrix metallopeptidase 9 (MMP9) proteins, whereas it increased the expression of E-cadherin in CCLP1 and SG-231 cells. Silencing of Twist1 expression enhanced the inhibitory effects of miR-186 on the proliferation, migration, and invasion of CCLP1 and SG-231 cells. In conclusion, miR-186 inhibited cell proliferation, migration, invasion, and epithelial–mesenchymal transition (EMT) through targeting Twist1 in human CCA. Thus, miR-186/Twist1 axis may benefit the development of therapies for CCA.