Deregulation of miRNAs in malignant pleural mesothelioma is associated with prognosis and suggests an alteration of cell metabolism

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.

Emerging roles of miR-145 in gastrointestinal cancers: A new paradigm

Gastrointestinal (GI) carcinomas are a group of cancers affecting the GI tract and digestive organs, such as the gastric, liver, bile ducts, pancreas, small intestine, esophagus, colon, and rectum. MicroRNAs (miRNAs) are small functional non-coding RNAs (ncRNAs) which are involved in regulating the expression of multiple target genes; mainly at the post-transcriptional level, via complementary binding to their 3'-untranslated region (3'-UTR). Increasing evidence has shown that miRNAs have critical roles in modulating of various physiological and pathological cellular processes and regulating the occurrence and development of human malignancies. Among them, miR-145 is recognized for its anti-oncogenic properties in various cancers, including GI cancers. MiR-145 has been implicated in diverse biological processes of cancers through the regulation of target genes or signaling, including, proliferation, differentiation, tumorigenesis, angiogenesis, apoptosis, metastasis, and therapy resistance. In this review, we have summarized the role of miR-145 in selected GI cancers and also its downstream molecules and cellular processes targets, which could lead to a better understanding of the miR-145 in these cancers. In conclusion, we reveal the potential diagnostic, prognostic, and therapeutic value of miR-145 in GI cancer, and hope to provide new ideas for its application as a biomarker as well as a therapeutic target for the treatment of these cancer.

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.

The role of mir-151a-5p in tumorigenesis; A systematic review

BACKGROUND

Highly supported microRNAs (miRNAs) are key players in cancer development. Each of these miRNAs may act as an oncomir, a tumor-suppressor, or both in various cancers. Mir-151a-5p is believed to be one of these miRNAs with diverse roles. We have conducted this systematic review to clarify the role of mir-151a-5p in formation of various cancers.

METHODS AND MATERIALS

We searched for existing articles in PubMed, Web of Science, Cochrane, Scopus, and RNAcentral databases up to November 2022. A total of 23 articles were qualified and included in the present systematic review. This review is registered on JBI at https://jbi.global/systematic-review-register. Expression levels, diagnostic and prognostic values, biological processes, and targeted downstream genes are included.

RESULTS

Assembled data indicate the expression levels of mir-151a-5p vary from down- to up-regulated based on the type of the cancer. Its functional role depends on the genetic profile of cancerous tissue. Results mostly point to the oncogenic role of this miRNA in Pituitary adenomas, Acute Myeloid Leukemia (AML), Endometrial, Lung, Barrett's carcinogenesis, Colorectal, Myelodysplastic syndromes, Hepatocellular carcinoma and Breast cancers, as its inhibited targets seem to be controlling several signaling pathways, cell adhesion, and cell cycle. At the same time, tumor-suppressing role has also been observed only in Malignant Pleural Mesothelioma, Central Nerve System (CNS) lymphoma, Chronic Myeloid and Acute Lymphocytic Leukemia. Two types of cancers, prostate and colon, show contradictory results as there are studies supporting both up- and down-regulation in these cancers. Pituitary adenomas, Barrett's carcinogenesis and CNS lymphomas are top cancers diagnosed with mir-151-5p. However, prognostic feature is only applicable to Lung adenocarcinoma.

DISCUSSION

Based on the present findings and further studies in the future, mir-151a-5p may be used as diagnostic and prognostic biomarkers or even a therapeutic target in cancer studies.

DATA AVAILABILITY STATEMENT

The articles used in this study can be found with the defined search phrase in mentioned databases. A list of selected articles will be available on reasonable requests.

ATG5 as biomarker for early detection of malignant mesothelioma

OBJECTIVES

Malignant pleural mesothelioma (MPM) is an aggressive disease with grim prognosis due to lack of effective treatment options. Disease prediction in association with early diagnosis may both contribute to improved MPM survival. Inflammation and autophagy are two processes associated with asbestos-induced transformation. We evaluated the level of two autophagic factors ATG5 and HMGB1, microRNAs (miRNAs) such as miR-126 and miR-222, and the specific biomarker of MPM, soluble mesothelin related proteins (Mesothelin) in asbestos-exposed individuals, MPM patients, and healthy subjects. The performance of these markers in detecting MPM was investigated in pre-diagnostic samples of asbestos-subjects who developed MPM during the follow-up and compared for the three groups.

RESULTS

The ATG5 best distinguished the asbestos-exposed subjects with and without MPM, while miR-126 and Mesothelin were found as a significant prognostic biomarker for MPM. ATG5 has been identified as an asbestos-related biomarker that can help to detect MPM with high sensitivity and specificity in pre-diagnostic samples for up to two years before diagnosis. To utilize this approach practically, higher number of cases has to be tested in order to give the combination of the two markers sufficient statistical power. Performance of the biomarkers should be confirmed by testing their combination in an independent cohort with pre-diagnostic samples.

The Genes-Stemness-Secretome Interplay in Malignant Pleural Mesothelioma: Molecular Dynamics and Clinical Hints

MPM has a uniquely poor somatic mutational landscape, mainly driven by environmental selective pressure. This feature has dramatically limited the development of effective treatment. However, genomic events are known to be associated with MPM progression, and specific genetic signatures emerge from the exceptional crosstalk between neoplastic cells and matrix components, among which one main area of focus is hypoxia. Here we discuss the novel therapeutic strategies focused on the exploitation of MPM genetic asset and its interconnection with the surrounding hypoxic microenvironment as well as transcript products and microvesicles representing both an insight into the pathogenesis and promising actionable targets.

Define the Two Molecular Subtypes of Epithelioid Malignant Pleural Mesothelioma

Malignant pleural mesothelioma (MPM) is a fatal disease of respiratory system. Despite the availability of invasive biomarkers with promising results, there are still significant diagnostic and therapeutic challenges in the treatment of MPM. One of three main mesothelioma cell types, epithelioid mesothelioma makes up approximately 70% of all mesothelioma cases. Different observational findings are under process, but the molecular heterogeneity and pathogenesis of epithelioid malignant pleural mesothelioma (eMPM) are still not well understood. Through molecular analysis, expression profiling data were used to determine the possibility and optimal number of eMPM molecular subtypes. Next, clinicopathological characteristics and different molecular pathways of each subtype were analyzed to prospect the clinical applications and advanced mechanisms of eMPM. In this study, we identified two distinct epithelioid malignant pleural mesothelioma subtypes with distinct gene expression patterns. Subtype I eMPMs were involved in steroid hormone biosynthesis, porphyrin and chlorophyll metabolism, and drug metabolism, while subtype II eMPMs were involved in rational metabolism, tyrosine metabolism, and chemical carcinogenesis pathways. Additionally, we identified potential subtype-specific therapeutic targets, including CCNE1, EPHA3, RNF43, ROS1, and RSPO2 for subtype I and CDKN2A and RET for subtype II. Considering the need for potent diagnostic and therapeutic biomarkers for eMPM, we are anticipating that our findings will help both in exploring underlying mechanisms in the development of eMPM and in designing targeted therapy for eMPM.

Novel Insights Into Mesothelioma Therapy: Emerging Avenues and Future Prospects

Malignant mesothelioma is a rare and aggressive cancer that develops in the thin layer surrounding the mesothelium and is mainly caused by asbestos exposure. Despite improvements in patient prognosis with conventional cancer treatments, such as surgery, chemotherapy, and radiotherapy, there are still no curative treatment modalities for advanced disease. In recent years, new therapeutic avenues have been explored. Improved understanding of the mechanisms underlying the dynamic tumor interaction with the immune system has led to the development of immunotherapeutic approaches. Numerous recent clinical trials have shown a desire to develop more effective treatments that can be used to fight against the disease. Immune checkpoint inhibitors, oncolytic adenoviruses, and their combination represent a promising strategy that can be used to synergistically overcome immunosuppression in the mesothelioma tumor microenvironment. This review provides a synthesized overview of the current state of knowledge on new therapeutic options for mesothelioma with a focus on the results of clinical trials conducted in the field.

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.

Splicing deregulation, microRNA and Notch aberrations: fighting the three-headed dog to overcome drug resistance in malignant mesothelioma

INTRODUCTION

Malignant mesothelioma (MMe) is an aggressive rare cancer of the mesothelium, associated with asbestos exposure. MMe is currently an incurable disease at all stages mainly due to resistance to treatments. It is therefore necessary to elucidate key mechanisms underlying chemoresistance, in an effort to exploit them as novel therapeutic targets.

AREAS COVERED

Chemoresistance is frequently elicited by microRNA (miRNA) alterations and splicing deregulations. Indeed, several miRNAs, such as miR-29c, have been shown to exert oncogenic or oncosuppressive activity. Alterations in the splicing machinery might also be involved in chemoresistance. Moreover, the Notch signaling pathway, often deregulated in MMe, plays a key role in cancer stem cells formation and self-renewal, leading to drug resistance and relapses.

EXPERT OPINION

The prognosis of MMe in patients varies among different tumors and patient characteristics, and novel biomarkers and therapies are warranted. This work aims at giving an overview of MMe, with a special focus on state-of-the-art treatments and new therapeutic strategies against vulnerabilities emerging from studies on epigenetics factors. Besides, this review is also the first to discuss the interplay between miRNAs and alternative splicing as well as the role of Notch as new promising frontiers to overcome drug resistance in MMe.

Long Non-coding RNA HOXA11-AS Facilitates Proliferation of Lung Adenocarcinoma Cells via Targeting the Let-7c-5p/IGF2BP1 Axis

Objective: This study investigates the relationship between the HOXA11-AS/let-7c-5p/IGF2BP1 regulatory axis and lung adenocarcinoma.

Methods: The expression levels of HOXA11-AS, let-7c-5p, and IGF2BP1 were evaluated in LUAD tissue and cell lines. Subcellular fractionation detection assay was adopted to verify the HOXA11-AS distribution in LUAD cells. The interaction relationship between let-7c-5p and HOXA11-AS or IGF2BP1 was validated by dual-luciferase reporter detection. In RNA binding protein immunoprecipitation assay, the binding relationship between HOXA11-AS and let-7c-5p was identified. The cell viability of transfected cells was tested by the Cell Counting Kit-8 assay. The mouse xenograft model was used to identify the effect of HOXA11-AS on tumor growth in vivo.

Results: Upregulation of lncRNA HOXA11-AS was found in LUAD, and suppression of HOXA11-AS could suppress the proliferative ability of LUAD cells. The let-7c-5p was expressed to be downregulated, which played an inhibitory role in LUAD cell proliferation. Let-7c-5p was negatively regulated by HOXA11-AS. HOXA11-AS promoted LUAD cell proliferation, while let-7c-5p had an inverse effect. Besides, IGF2BP1, regulated by let-7c-5p, had a positive relation with HOXA11-AS, while overexpression of IGF2BP1 could suppress the inhibition of silencing HOXA11-AS on LUAD cell proliferation. Experiments on mice confirmed that HOXA11-AS facilitated LUAD cell growth in vivo through regulating the let-7c-5p/IGF2BP1 axis.

Conclusion: HOXA11-AS promoted LUAD cell proliferation by targeting let-7c-5p/IGF2BP1, which could be potential molecular targets for LUAD.

Effects of hsa-mir-145-5p on the Regulation of msln Expression in Colorectal Adenocarcinoma

Colorectal cancer (CRC) is one of the most common gastrointestinal cancers in the world, and its incidence is increasing all over the world including China. In recent years, research data show that some miRNAs are differentially expressed in cancer tissues, and their expression is closely contributed with the prognosis of CRC. Microarray technology was used, and 179 miRNAs were screened out with significantly altered expression in CRC tissues compared with adjacent tissues. The expression of mir-145-5p in tumor tissues was 3.48 times lower than that in normal tissues. Using bioinformatics technology and network resource prediction, we found that mir-145-5p had a potential target gene relationship with msln gene. Then, qRT-PCR was used to validate the expression level of mir-145-5p and msln mRNA in CRC and paracancerous tissues. The results showed that msln mRNA was higher than in normal tissues, while mir-145-5p was lower, with statistically significant difference (P < 0.01, n = 3). Furthermore, the expression of msln protein in CRC and normal colorectal tissues was detected by protein mass spectrometry (MRM) (n = 3) and immunohistochemistry in a total case of 30 colorectal cancer tissues and normal tissues. Result showed that the positive expression of msln in CRC was higher than that in normal colorectal tissues, 1.38e-6 and 1.89e-6, respectively (P < 0.01, n = 3). Furthermore, in 48 h RTCA real-time monitoring experiment, mir-145-5p showed inhibitory effect on the proliferation of colo320 cells stimulated by msln. This study demonstrated that msln is a target gene of mir-145-5p in CRC. Besides, mir-145-5p negatively regulates the proliferation of CRC colo320 cells through downregulating msln gene expression in CRC colo320 cells.

Extracellular vesicles derived from tumour cells as a trigger of energy crisis in the skeletal muscle

BACKGROUND

Cachexia, a syndrome frequently occurring in cancer patients, is characterized by muscle wasting, altered energy and protein metabolism and impaired myogenesis. Tumour-derived microvesicles (TMVs) containing proteins, messenger RNAs (mRNAs), and non-coding RNAs could contribute to cancer-induced muscle wasting.

METHODS

Differential ultracentrifugation was used to isolate TMVs from the conditioned medium of Lewis lung carcinoma and C26 colon carcinoma cell cultures. TMVs were added to the culture medium of C2C12 myoblasts and myotubes for 24-48-72 h, and the effects on protein and energy metabolism were assessed. TMVs were also isolated from the blood of C26-bearing mice. MicroRNA (miR) profile of TMVs was obtained by RNA-seq and validated by digital drop PCR. Selected miRs were overexpressed in C2C12 myoblasts to assess the effects on myogenic differentiation.

RESULTS

Differentiation was delayed in C2C12 myoblasts exposed to TMVs, according to reduced expression of myosin heavy chain (MyHC; about 62% of controls at Day 4) and myogenin (about 68% of controls at Day 4). As for myotubes, TMVs did not affect the expression of MyHC, while revealed able to modulate mitochondria and oxidative metabolism. Indeed, reduced mRNA levels of PGC-1α (C = 1 ± 0.2, TMV = 0.57 ± 0.06, normalized fold change, P < 0.05) and Cytochrome C (C = 1 ± 0.2, TMV = 0.65 ± 0.04, normalized fold change, P < 0.05), associated with increased BNIP3 expression (C = 1 ± 0.1, TMV = 1.29 ± 0.2, normalized fold change, P < 0.05), were observed, suggesting reduced mitochondrial biogenesis/amount and enhanced mitophagy. These changes were paralleled by decreased oxygen consumption (C = 686.9 ± 44 pmol/min, TMV = 552.25 ± 24 pmol/min, P < 0.01) and increased lactate levels (C = 0.0063 ± 0.00045 nmol/μL, TMV = 0.0094 ± 0.00087 nmol/μL, P < 0.01). A total of 118 miRs were found in MVs derived from the plasma of the C26 hosts; however, only three of them were down-regulated (RNA-seq): miR-181a-5p (-1.46 fold change), miR-375-3p (-2.52 fold change), and miR-455-5p (-3.87 fold change). No correlation could be observed among miRs in the MVs obtained from the blood of the C26 host and those released by C26 cells in the culture medium. Overexpression of miR-148a-3p and miR-181a-5p in C2C12 myoblasts revealed the ability to impinge on the mRNA levels of Myf5, Myog, and MyHC (Myh4 and Myh7).

CONCLUSIONS

These results show that in C2C12 cultures, TMVs are able to affect both differentiation and the mitochondrial system. Such effects could be related to TMV-contained miRs.

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.

Update of in vitro, in vivo and ex vivo fluoro-edenite effects on malignant mesothelioma: A systematic review (Review)

Fluoro-edenite (FE), asbestiform fiber found in Biancavilla (Sicily, Italy), presents various characteristics similar to the asbestos group, in particular two fibrous phases tremolite and actinolite. Indeed, epidemiological studies have shown that FE fibers have similar effects to those of asbestos fibers. Such studies have reported a high incidence of malignant mesothelioma (MM), an aggressive neoplasm of the serosal membranes lining the pleural cavity, in individuals residing there due to FE exposure in Biancavilla related to environmental contamination. Evidence has led to the classification of FE as a Group 1 human carcinogen by the International Agency for Research on Cancer (IARC). The aim of this systematic review is to compare the results achieved in in vitro, in vivo and ex vivo experimental studies involving FE in order to update the current knowledge on the pathogenesis and molecular mechanisms responsible for FE-mediated MM development as well as the availability of effective biomarkers for MM prevention and diagnosis. This review is focused on the pathophysiological mechanisms mediated by inflammation induced by FE fiber exposure and which are responsible for MM development. This review also discusses the discovery of new diagnostic and prognostic biomarkers for the management of this pathology. It is known that the risk of cancer development increases with chronic inflammation, arising from enhanced reactive oxygen species (ROS) and NO^• production stimulated by the body to remove exogenous agents, causing DNA damage and enhanced signal transduction that may lead to activation of oncogenes. Studies concerning MM biomarker discovery indicate that several biomarkers have been proposed for MM, but mesothelin is the only Food and Drug Administration (FDA)-approved biomarker for MM, with limitations. In recent studies, in silico analysis to identify selected miRNAs highly deregulated in cancer samples when compared with normal control have been developed. This in silico approach could represent an effort in the field of biomarker discovery for MM.

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.

Temporally Altered miRNA Expression in a Piglet Model of Hypoxic Ischemic Brain Injury

Hypoxic ischemic encephalopathy (HIE) is the most frequent cause of acquired infant brain injury. Early, clinically relevant biomarkers are required to allow timely application of therapeutic interventions. We previously reported early alterations in several microRNAs (miRNA) in umbilical cord blood at birth in infants with HIE. However, the exact timing of these alterations is unknown. Here, we report serial changes in six circulating, cross-species/bridging biomarkers in a clinically relevant porcine model of neonatal HIE with functional analysis. Six miRNAs—miR-374a, miR-181b, miR-181a, miR-151a, miR-148a and miR-128—were significantly and rapidly upregulated 1-h post-HI. Changes in miR-374a, miR-181b and miR-181a appeared specific to moderate-severe HI. Histopathological injury and five miRNAs displayed positive correlations and were predictive of MRS Lac/Cr ratios. Bioinformatic analysis identified that components of the bone morphogenic protein (BMP) family may be targets of miR-181a. Inhibition of miR-181a increased neurite length in both SH-SY5Y cells at 1 DIV (days in vitro) and in primary cultures of rat neuronal midbrain at 3 DIV. In agreement, inhibition of miR-181a increased expression of BMPR2 in differentiating SH-SY5Y cells. These miRNAs may therefore act as early biomarkers of HIE, thereby allowing for rapid diagnosis and timely therapeutic intervention and may regulate expression of signalling pathways vital to neuronal survival.

Lipids and cancer: Emerging roles in pathogenesis, diagnosis and therapeutic intervention

With the advent of effective tools to study lipids, including mass spectrometry-based lipidomics, lipids are emerging as central players in cancer biology. Lipids function as essential building blocks for membranes, serve as fuel to drive energy-demanding processes and play a key role as signaling molecules and as regulators of numerous cellular functions. Not unexpectedly, cancer cells, as well as other cell types in the tumor microenvironment, exploit various ways to acquire lipids and extensively rewire their metabolism as part of a plastic and context-dependent metabolic reprogramming that is driven by both oncogenic and environmental cues. The resulting changes in the fate and composition of lipids help cancer cells to thrive in a changing microenvironment by supporting key oncogenic functions and cancer hallmarks, including cellular energetics, promoting feedforward oncogenic signaling, resisting oxidative and other stresses, regulating intercellular communication and immune responses. Supported by the close connection between altered lipid metabolism and the pathogenic process, specific lipid profiles are emerging as unique disease biomarkers, with diagnostic, prognostic and predictive potential. Multiple preclinical studies illustrate the translational promise of exploiting lipid metabolism in cancer, and critically, have shown context dependent actionable vulnerabilities that can be rationally targeted, particularly in combinatorial approaches. Moreover, lipids themselves can be used as membrane disrupting agents or as key components of nanocarriers of various therapeutics. With a number of preclinical compounds and strategies that are approaching clinical trials, we are at the doorstep of exploiting a hitherto underappreciated hallmark of cancer and promising target in the oncologist's strategy to combat cancer.

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.

Malignant Pleural Mesothelioma: Genetic and Microenviromental Heterogeneity as an Unexpected Reading Frame and Therapeutic Challenge

Mesothelioma is a malignancy of serosal membranes including the peritoneum, pleura, pericardium and the tunica vaginalis of the testes. Malignant mesothelioma (MM) is a rare disease with a global incidence in countries like Italy of about 1.15 per 100,000 inhabitants. Malignant Pleural Mesothelioma (MPM) is the most common form of mesothelioma, accounting for approximately 80% of disease. Although rare in the global population, mesothelioma is linked to industrial pollutants and mineral fiber exposure, with approximately 80% of cases linked to asbestos. Due to the persistent asbestos exposure in many countries, a worldwide progressive increase in MPM incidence is expected for the current and coming years. The tumor grows in a loco-regional pattern, spreading from the parietal to the visceral pleura and invading the surrounding structures that induce the clinical picture of pleural effusion, pain and dyspnea. Distant spreading and metastasis are rarely observed, and most patients die from the burden of the primary tumor. Currently, there are no effective treatments for MPM, and the prognosis is invariably poor. Some studies average the prognosis to be roughly one-year after diagnosis. The uniquely poor mutational landscape which characterizes MPM appears to derive from a selective pressure operated by the environment; thus, inflammation and immune response emerge as key players in driving MPM progression and represent promising therapeutic targets. Here we recapitulate current knowledge on MPM with focus on the emerging network between genetic asset and inflammatory microenvironment which characterize the disease as amenable target for novel therapeutic approaches.

MicroRNAs diagnostic and prognostic value as predictive markers for malignant mesothelioma

Malignant mesothelioma is an aggressive tumor resistant to current therapies with a latency period ranging between 20 and 60 years, caused by inhalation of asbestos fibers, that continues to represent a social and healthcare issue. The high percentage of people exposed to asbestos for professional or environmental reasons is associated with the high biopersistence of its fibers and with its widespread use in the last century. Approximately 20-40% of men report an occupational history that might have caused the workplace exposure (criteria Helsinki, 1997). Some authors are evaluating the possible use of bioindicators as a screening and early diagnosis tool. In this regard, the use of microRNAs has been proposed as powerful diagnostic and prognostic biomarkers for many tumors and human diseases. This review focuses on the current state of knowledge on the key role of microRNAs expression as new malignant mesothelioma biomarkers, in early clinical diagnostic applications.

Identifying Small Molecule-miRNA Associations Based on Credible Negative Sample Selection and Random Walk

Recently, many studies have demonstrated that microRNAs (miRNAs) are new small molecule drug targets. Identifying small molecule-miRNA associations (SMiRs) plays an important role in finding new clues for various human disease therapy. Wet experiments can discover credible SMiR associations; however, this is a costly and time-consuming process. Computational models have therefore been developed to uncover possible SMiR associations. In this study, we designed a new SMiR association prediction model, RWNS. RWNS integrates various biological information, credible negative sample selections, and random walk on a triple-layer heterogeneous network into a unified framework. It includes three procedures: similarity computation, negative sample selection, and SMiR association prediction based on random walk on the constructed small molecule-disease-miRNA association network. To evaluate the performance of RWNS, we used leave-one-out cross-validation (LOOCV) and 5-fold cross validation to compare RWNS with two state-of-the-art SMiR association methods, namely, TLHNSMMA and SMiR-NBI. Experimental results showed that RWNS obtained an AUC value of 0.9829 under LOOCV and 0.9916 under 5-fold cross validation on the SM2miR1 dataset, and it obtained an AUC value of 0.8938 under LOOCV and 0.9899 under 5-fold cross validation on the SM2miR2 dataset. More importantly, RWNS successfully captured 9, 17, and 37 SMiR associations validated by experiments among the predicted top 10, 20, and 50 SMiR candidates with the highest scores, respectively. We inferred that enoxacin and decitabine are associated with mir-21 and mir-155, respectively. Therefore, RWNS can be a powerful tool for SMiR association prediction.

Exosomal miRNA profiling before and after surgery revealed potential diagnostic and prognostic markers for lung adenocarcinoma

Exosome is a crucial manner for cancer cell to cell communication and circulating exosomes sever as promising diagnostic and prognostic markers for various types of diseases. A predominant type of cargo of exosome is small RNAs, especially miRNAs. Here, we profiled plasma exosomal miRNAs of six lung adenocarcinoma patients before and after surgery, as well as six healthy individuals as normal control. Our profiling revealed 38 upregulated and 37 downregulated exosomal miRNAs in the plasma of lung adenocarcinoma patients. Additionally, we found that most upregulated miRNAs were increased in the lung adenocarcinoma samples of TCGA database. We further evaluated the correlation between the upregulated exosomal miRNAs and overall survival with Kaplan-Meier survival analysis using online databases. Our results suggested that exosomal miR-151a-5p, miR-10b-5p, miR-192-5p, miR-106b-3p, and miR-484 are potential prognostic markers for lung adenocarcinoma. Importantly, we validated candidate miRNAs in lung adenocarcinoma patients before and after surgery as well as in healthy controls and found that miR-484 was significantly increased in the plasma of lung adenocarcinoma patients and strikingly decreased post-surgery. Hence, we provided novel information on lung adenocarcinoma-derived exosomal miRNA and potential non-invasive diagnostic and prognostic markers for lung adenocarcinoma.

MicroRNA-98 is a prognostic factor for asbestos-induced mesothelioma

Malignant pleural mesothelioma (MPM) is a type of cancer characterized by a short survival time and poor prognosis. Malignant pleural mesothelioma is most frequently associated with exposure to asbestos and other elongated mineral fibers. The aim of this study was to examine molecular differences between asbestos-exposed and non-exposed MPM patients and assess prognostic significances of molecular factors. Clinical and genetic data were downloaded from Cancer Genome Atlas. To identify the molecular differences, Significant Analysis of Microarray method was used. Prognostic significances of differentially expressed genes were confirmed by using Kaplan-Meier curve with the Log-Rank test. Although mRNAs did not exhibit any significant differences between the two patient groups, nine miRNAs were found to be down-regulated in the asbestos-exposed group. The top five pathways most relevant to the selected miRNAs were extracted through pathway enrichment analysis. Survival analysis revealed that high expression of only hsa-miR-98 was significantly associated with poor prognosis in patients with asbestos-exposed MPM. Evidence suggests that management of the aggressiveness and progression of asbestos-induced MPM may require high levels of hsa-miR-98 due to its tumor-suppressive role. This study might be helpful in enhancing our understanding of the biological mechanisms underlying asbestos-induced MPM and for acquiring greater insights into targeted therapy.Abbreviations: FDR: false discovery rate; MM: malignant mesothelioma; MPM: malignant pleural mesothelioma; mRNA: messenger RNA; miRNA: microRNA; SAM: significance analysis of microarrays; TCGA: the cancer genome atlas.

MicroRNAs in Tumor Cell Metabolism: Roles and Therapeutic Opportunities

Dysregulated metabolism is a common feature of cancer cells and is considered a hallmark of cancer. Altered tumor-metabolism confers an adaptive advantage to cancer cells to fulfill the high energetic requirements for the maintenance of high proliferation rates, similarly, reprogramming metabolism confers the ability to grow at low oxygen concentrations and to use alternative carbon sources. These phenomena result from the dysregulated expression of diverse genes, including those encoding microRNAs (miRNAs) which are involved in several metabolic and tumorigenic pathways through its post-transcriptional-regulatory activity. Further, the identification of key actionable altered miRNA has allowed to propose novel targeted therapies to modulated tumor-metabolism. In this review, we discussed the different roles of miRNAs in cancer cell metabolism and novel miRNA-based strategies designed to target the metabolic machinery in human cancer.

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).

Exosomal miR-16-5p as a target for malignant mesothelioma

Malignant mesothelioma (MM) is an asbestos-induced cancer arising on the mesothelial surface of organ cavities. MM is essentially incurable without a means of early diagnosis and no successful standard of care. These facts indicate a deep chasm of knowledge that needs to be filled. Our group recently delved into MM tumor biology from the perspective of exosome-contained microRNAs (miRNAs). We discovered that the most abundant miRNAs in MM cancer exosomes were tumor suppressors, particularly miR-16-5p. This observation lead us to hypothesize that MM cells preferentially secreted tumor-suppressor miRNAs via exosomes. Through separate avenues of potential therapeutic advance, we embarked on an innovative strategy to kill MM tumor cells. We employed small molecule inhibitors to block exosome secretion, thereby reducing miR-16-5p exosome loss and replenishing cellular miR-16-5p leading to reduced tumorigenic capacity and miR-16-5p target oncoproteins CCND1 and BCL2. Additionally, we force-fed MM tumor exosomes back to MM tumor cells, which led to cell death, and a reduction in the same oncoproteins. We recapitulated these results with direct transfection of miR-16-5p, confirmed that this is a cancer-cell specific effect, and elucidated a part of the miR-16-5p mechanism of exosome loading.

Exosomal transfer of miR-126 promotes the anti-tumour response in malignant mesothelioma: Role of miR-126 in cancer-stroma communication

MiR-126 has been shown to suppress malignant mesothelioma (MM) by targeting cancer-related genes without inducing toxicity or histopathological changes. Exosomes provide the opportunity to deliver therapeutic cargo to cancer stroma. Here, a tumour stromal model composed of endothelial cells (HUVECs), fibroblasts (IMR-90 cells), non-malignant mesothelial cells (Met-5A cells) and MM cells (H28 and MM-B1 cells) was used. The cells were treated with exosomes from HUVECs carrying endogenous (exo-HUVEC) and enriched miR-126 (exo-HUVEC^miR-126), and the uptake/turnover of exosomes; miR-126 distribution within the stroma; and effect of miR-126 on cell signalling, angiogenesis and cell proliferation were evaluated. Based on the sensitivity of MM cells to exo-HUVEC miR-126 treatment, miR-126 was distributed differently across stromal cells. The reduced miR-126 content in fibroblasts in favour of endothelial cells reduced angiogenesis and suppressed cell growth in an miR-126-sensitive environment. Conversely, the accumulation of miR-126 in fibroblasts and the reduced level of miR-126 in endothelial cells induced tube formation in an miR-126-resistant environment via VEGF/EGFL7 upregulation and IRS1-mediated cell proliferation. These findings suggest that transfer of miR-126 via HUVEC-derived exosomes represents a novel strategy to inhibit angiogenesis and cell growth in MM.

What can independent research for mesothelioma achieve to treat this orphan disease?

Introduction: Malignant pleural mesothelioma (MPM) is a rare neoplasm with a poor prognosis, as current therapies are ineffective. Despite the increased understanding of the molecular biology of mesothelioma, there is still a lack of drugs that dramatically enhance patient survival. Area Covered: This review discusses recent and complete clinical trials supported by the NIH, other U.S. Federal agencies, universities and organizations found on clinicaltrials.gov. Firstly, chemotherapy-based trials are described, followed by immunotherapy and multitargeted therapy. Then we introduce drug repositioning and the use of drug docking as tools to find new interesting molecules. Finally, we highlight potential molecular pathways that may play a role in mesothelioma biology and therapy. Expert Opinion: Numerous biases are present in the clinical trials due to a restricted number of cases, inappropriate endpoints and inaccurate stratification of patients which delay the finding of a treatment for MPM. The most crucial issue of independent research for MPM is the lack of more substantive funding to translate these findings to the clinical setting. However, this approach is not necessarily scientific given the low mutational load of mesothelioma relative to other cancers, and therefore patients need a more solid rationale to have a good chance of successful treatment.

A perspective on the diagnostics, prognostics, and therapeutics of microRNAs of triple-negative breast cancer

Triple-negative breast cancer (TNBC) is the most aggressive and prevalent subtype of breast cancer in women worldwide. Currently, chemotherapy remains the main modality for the treatment at an early stage, as there is no approved targeted therapy for early TNBC. In this review, we investigate the use of microRNAs (miRNAs), which play a key role in the post-transcriptional regulation of genes involved in the key biological processes, namely proliferation, differentiation, angiogenesis, migration, apoptosis, and carcinogenesis. Here, we emphasize the importance of the recent advances related to miRNAs, involving diagnosis, prognosis, and treatment of TNBC. We focus on the development, optimization, and stabilization of miRNA-based drugs; improvement of miRNA delivery; and control of the off-target effects of miRNA therapeutics. We speculate as to which features may present themselves as promising approaches in the treatment of TNBC.

Development and Validation of a Prognostic Signature for Malignant Pleural Mesothelioma

Introduction: Dysregulated genes play a critical role in the development and progression of cancer, suggesting their potential as novel independent biomarkers for cancer diagnosis and prognosis. Prognostic model-based gene expression profiles are not widely utilized in clinical medicine. We investigated the prognostic significance of an expression profile-based gene signature for outcome prediction in patients with malignant pleural mesothelioma (MPM).

Methods: The gene expression profiles of a large cohort of patients with MPM were obtained and analyzed by repurposing publicly available microarray data. A gene-based risk score model was developed with the training dataset and then validated with the TCGA-MESO (mesothelioma) dataset. The time-dependent receiver operating characteristic (ROC) curve was used to evaluate the prognostic performance of survival prediction. The biological function of the prognostic genes was predicted using bioinformatics analysis.

Results: Three genes in the training dataset (GSE2549) were identified as significantly associated with the overall survival (OS) of patients with MPM and were combined to develop a three-gene prognostic signature to stratify patients into low-risk and high-risk groups. The MPM patients of the training dataset in the low-risk group exhibited longer OS than those in the high-risk group (HR = 0.25, 95% CI = 0.11–0.56, P < 0.001). Similar prognostic values for the three-gene signature were observed in the validated TCGA-MESO cohort (HR = 0.53 95% CI = 0.33–0.85, P = 0.008). ROC analysis also demonstrated the good performance in predicting 3-year OS in the GEO and TCGA cohorts (KM-AUC for GEO = 0.989, KM-AUC for TCGA = 0.618). The C-statistic for the 3-gene model was 0.761. Validation with TCGA-MESO confirmed the model's ability to discriminate between risk groups in an alternative data set with fair performance (C-statistic: 0.68). Functional enrichment analysis suggested that these three genes may be involved in genetic and epigenetic events with known links to MPM.

Conclusions: This study has identified and validated a novel 3-gene model to reliably discriminate patients at high and low risk of death in unselected populations of patients with MPM. Further larger, prospective multi-institutional cohort studies are necessary to validate this model.

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

Malignant pleural mesothelioma (MPM) is a rare and aggressive tumor with a variable incidence among different countries. Occupational asbestos exposure is the most important etiological factor and a very long latency period is widely reported. In the early phase of the disease, clinical signs are absent or not specific. For this reason, the diagnosis is frequently achieved only in the advanced stages. The histopathological diagnosis per se is also very complex, and no known factor can predict the prognosis with certainty. Nonetheless, current survival rates remain very low, despite the use of standard treatments, which include surgery, chemotherapy and radiotherapy. The identification of new prognostic and/or diagnostic biomarkers, and the discovery of therapeutic targets is a priority and could lead to a real significant impact on the management of malignant pleural mesothelioma. In this scenario, the role of microRNAs is becoming increasingly relevant, with the promise of a quick translation in the current clinical practice. Despite the relative novelty of this field, the number of works and candidate microRNAs that are present in literature is striking. Unfortunately, to date the microRNAs with the most clinical relevance for MPM are still matter of debate, probably due to the variety of approaches, techniques, and collected samples. Although specific microRNAs (e.g., let-7, miR-15 and miR-16, miR-21, miR-34a, and the miR-200 family) have been reported several times from different groups, the heterogeneity of published data reinforces the need of more comprehensive and unified studies on this topic. In this review we collect and discuss the studies focused on the involvement of microRNAs in different aspects of MPM, from their biological role in tumorigenesis and progression, to their possible application as diagnostic, prognostic and predictive biomarkers. Lastly, we examine their potential value as for the design of therapeutic approaches that could benefit MPM patients.

Clinical significance of serum DRAM1 mRNA, ARSA mRNA, hsa-miR-2053 and lncRNA-RP1-86D1.3 axis expression in malignant pleural mesothelioma

AIM AND BACKGROUND

Malignant pleural mesothelioma (MPM) is a lethal cancer mainly caused by chronic exposure of asbestos. In this pilot study, we aimed to assess the expression of serum RNA-based biomarker panel exploring their clinical utility as diagnostic and prognostic biomarkers for MPM.

METHODS

We have selected an MPM-specific RNA-based biomarker panel through bioinformatics analysis based on the integration of DNA damage regulated autophagy modulator 1 (DRAM1) and arylsulfatase A ( ARSA) gene expression with their epigenetic regulators microRNA ( miR-2053) and long noncoding RNA ( lncRNA-RP1-86D1.3). Then, quantitative real-time polymerase chain reaction (qPCR) validation in sera of 60 MPM patients, 20 chronic asbestos exposure patients, and 20 healthy volunteers was done. Lastly, the prognostic power of the selected panel was assessed.

RESULTS

The expression of serum DRAM1 messenger RNA (mRNA), ARSA mRNA, hsa-miR-2053 and lncRNA-RP1-86D1.3 were positive in 78.3%, 90%, 85%, and 83.3% of MPM patients, respectively. The RNA-based biomarker panel was able to discriminate between MPM patients and controls with high accuracy and their combined sensitivity reached 100% for the diagnosis of MPM. Kaplan-Meier analysis showed that hsa-miR-2053 is an independent prognostic factor of MPM.

CONCLUSION

Our preliminary data revealed that the chosen RNAs play an important role in driving MPM development and progression.

Mesotheliomas in Genetically Engineered Mice Unravel Mechanism of Mesothelial Carcinogenesis

Malignant mesothelioma (MM), a rare and severe cancer, mainly caused as a result of past-asbestos exposure, is presently a public health concern. Current molecular studies aim to improve the outcome of the disease, providing efficient therapies based on the principles of precision medicine. To model the molecular profile of human malignant mesothelioma, animal models have been developed in rodents, wild type animals and genetically engineered mice harbouring mutations in tumour suppressor genes, especially selecting genes known to be inactivated in human malignant mesothelioma. Animals were either exposed or not exposed to asbestos or to other carcinogenic fibres, to understand the mechanism of action of fibres at the molecular level, and the role of the selected genes in mesothelial carcinogenesis. The aim of the manuscript was to compare mesothelioma models to human malignant mesothelioma and to specify the clue genes playing a role in mesothelial carcinogenesis. Collectively, MM models recapitulate the clinical features of human MM. At least two altered genes are needed to induce malignant mesothelioma in mice. Two pathways regulated by Cdkn2a and Trp53 seem independent key players in mesothelial carcinogenesis. Other genes and pathways appear as bona fide modulators of the neoplastic transformation.

Genomics and Epigenetics of Malignant Mesothelioma

Malignant mesothelioma is an aggressive and lethal asbestos-related disease. Diagnosis of malignant mesothelioma is particularly challenging and is further complicated by the lack of disease subtype-specific markers. As a result, it is especially difficult to distinguish malignant mesothelioma from benign reactive mesothelial proliferations or reactive fibrosis. Additionally, mesothelioma diagnoses can be confounded by other anatomically related tumors that can invade the pleural or peritoneal cavities, collectively resulting in delayed diagnoses and greatly affecting patient management. High-throughput analyses have uncovered key genomic and epigenomic alterations driving malignant mesothelioma. These molecular features have the potential to better our understanding of malignant mesothelioma biology as well as to improve disease diagnosis and patient prognosis. Genomic approaches have been instrumental in identifying molecular events frequently occurring in mesothelioma. As such, we review the discoveries made using high-throughput technologies, including novel insights obtained from the analysis of the non-coding transcriptome, and the clinical potential of these genetic and epigenetic findings in mesothelioma. Furthermore, we aim to highlight the potential of these technologies in the future clinical applications of the novel molecular features in malignant mesothelioma.

Biomarkers for Early Diagnosis and Prognosis of Malignant Pleural Mesothelioma: The Quest Goes on

Malignant pleural mesothelioma (MM) is a highly aggressive tumor characterized by a poor prognosis. Although its carcinogenesis mechanism has not been strictly understood, about 80% of MM can be attributed to occupational and/or environmental exposure to asbestos fibers. The identification of non-invasive molecular markers for an early diagnosis of MM has been the subject of several studies aimed at diagnosing the disease at an early stage. The most studied biomarker is mesothelin, characterized by a good specificity, but it has low sensitivity, especially for non-epithelioid MM. Other protein markers are Fibulin-3 and osteopontin which have not, however, showed a superior diagnostic performance. Recently, interesting results have been reported for the HMGB1 protein in a small but limited series. An increase in channel proteins involved in water transport, aquaporins, have been identified as positive prognostic factors in MM, high levels of expression of aquaporins in tumor cells predict an increase in survival. MicroRNAs and protein panels are among the new indicators of interest. None of the markers available today are sufficiently reliable to be used in the surveillance of subjects exposed to asbestos or in the early detection of MM. Our aim is to give a detailed account of biomarkers available for MM.

Progress in the Management of Malignant Pleural Mesothelioma in 2017

Malignant pleural mesothelioma (MPM) is an uncommon, almost universally fatal, asbestos-induced malignancy. New and effective strategies for diagnosis, prognostication, and treatment are urgently needed. Herein we review the advances in MPM achieved in 2017. Whereas recent epidemiological data demonstrated that the incidence of MPM-related death continued to increase in United States between 2009 and 2015, new insight into the molecular pathogenesis and the immunological tumor microenvironment of MPM, for example, regarding the role of BRCA1 associated protein 1 and the expression programmed death receptor ligand 1, are highlighting new potential therapeutic strategies. Furthermore, there continues to be an ever-expanding number of clinical studies investigating systemic therapies for MPM. These trials are primarily focused on immunotherapy using immune checkpoint inhibitors alone or in combination with other immunotherapies and nonimmunotherapies. In addition, other promising targeted therapies, including pegylated adenosine deiminase (ADI-PEG20), which focuses on argininosuccinate synthase 1-deficient tumors, and tazemetostat, an enhancer of zeste 2 polycomb repressive complex 2 subunit inhibitor of BRCA1 associated protein 1 gene (BAP1)-deficient tumors, are currently being explored.

Serum mesothelin and other biomarkers: what have we learned in the last decade?

In the last decade there is been much interest in noninvasive, economic and well-accepted diagnostic tests for screening of subjects exposed to asbestos, and in patients with malignant pleuric mesothelioma (MPM) for diagnosis or monitoring response to treatment. Several biomarkers have been suggested as tools for screening and early diagnosis of MPM. Currently, in patients with MPM, have been reported high levels of soluble mesothelin-related peptides (SMRP), plasmatic osteopontin (pOPN), vimentin, fibulin-3 and many others as promising marker for diagnosis, even their use in prevention monitoring is still discussed. In this type of disease, a key role could be played by miRNAs, which expression has been investigated in a large series of MPM to examine new pathways useful in diagnosis, prognosis and therapy. An altered expression of some proteins has been reported, useful as biomarkers, in comparative proteomic analysis of malignant pleural mesothelioma. New promising markers are nowadays under study and alone or better in combination, they'll be very helpful in diagnosing, monitoring mesothelioma patients or for screening of risk groups.

Biomarkers in the prevention and follow-up of workers exposed to asbestos

Although in most developed countries the use of asbestos is banned, there is still a consistent portion of the world where asbestos extraction, trading and manufacturing of asbestos-made products is largely diffuse. Worldwide, hundreds of millions of people are at risk of developing an asbestos caused disease because of occupational, environmental or domestic exposure. The WHO estimates that asbestos is responsible for more than 100,000 deaths yearly. This scenario has prompted the research on biomarkers potentially useful for early diagnosis, prognosis and preventive programs on exposed population as well. Here we reviewed the up-to-date literature on this field of research highlighting that along with mesothelin and osteopontin (OPN), some more recently investigated molecules, such as high mobility group box 1 (HMGB1) protein, fibulin-3 and some miRNAs showed very promising. Most of the carried-out studies showed an interesting diagnostic and prognostic performance of some biomarkers, but since they usually lack adequate either specificity or sensitivity, their use in screening or in preventive programs is still not recommended on a routine basis. However, this review suggests the need for more reliable experimental design involving larger population and preferring longitudinal screening of asbestos exposed individuals rather than a single baseline assessment investigation. In addition, given their better diagnostic accuracy, the use of panels including several biomarkers is highly recommended.

Targeting microRNA to improve diagnostic and therapeutic approaches for malignant mesothelioma

Malignant mesothelioma is an aggressive and often fatal cancer associated with asbestos exposure. The disease originates in the mesothelial lining of the serosal cavities, most commonly affecting the pleura. Survival rates are low as diagnosis often occurs at an advanced stage and current treatments are limited. Identifying new diagnostic and therapeutic targets for mesothelioma remains a priority, particularly for the new wave of victims exposed to asbestos through do-it-yourself renovations and in countries where asbestos is still mined and used. Recent advances have demonstrated a biological role for the small but powerful gene regulators microRNA (miRNA) in mesothelioma. A number of potential therapeutic targets have been identified. MiRNA have also become popular as potential biomarkers for mesothelioma due to their stable expression in bodily fluid and tissues. In this review, we highlight the current challenges associated with the diagnosis and treatment of mesothelioma and discuss how targeting miRNA may improve diagnostic, prognostic and therapeutic approaches.