The Role of E-Cadherin and microRNA on FAK Inhibitor Response in Malignant Pleural Mesothelioma (MPM).

Malignant pleural mesothelioma (MPM) is an aggressive malignancy with limited effective treatment options. Focal adhesion kinase (FAK) inhibitors have been shown to efficiently suppress MPM cell growth initially, with limited utility in the current clinical setting. In this study, we utilised a large collection of MPM cell lines and MPM tissue samples to study the role of E-cadherin (CDH1) and microRNA on the efficacy of FAK inhibitors in MPM. The immunohistochemistry (IHC) results showed that the majority of MPM FFPE samples exhibited either the absence of, or very low, E-cadherin protein expression in MPM tissue. We showed that MPM cells with high CDH1 mRNA levels exhibited resistance to the FAK inhibitor PND-1186. In summary, MPM cells that did not express CDH1 mRNA were sensitive to PND-1186, and MPM cells that retained CDH1 mRNA were resistant. A cell cycle analysis showed that PND-1186 induced cell cycle disruption by inducing the G2/M arrest of MPM cells. A protein-protein interaction study showed that EGFR is linked to the FAK pathway, and a target scan of the microRNAs revealed that microRNAs (miR-17, miR221, miR-222, miR137, and miR148) interact with EGFR 3'UTR. Transfection of MPM cells with these microRNAs sensitised the CHD1-expressing FAK-inhibitor-resistant MPM cells to the FAK inhibitor.

KCa1.1, a calcium-activated potassium channel subunit alpha 1, is targeted by miR-17-5p and modulates cell migration in malignant pleural mesothelioma.

BACKGROUND: Malignant pleural mesothelioma (MPM) is an aggressive, locally invasive, cancer elicited by asbestos exposure and almost invariably a fatal diagnosis. To date, we are one of the leading laboratory that compared microRNA expression profiles in MPM and normal mesothelium samples in order to identify dysregulated microRNAs with functional roles in mesothelioma. We interrogated a significant collection of MPM tumors and normal pleural samples in our biobank in search for novel therapeutic targets. METHODS: Utilizing mRNA-microRNA correlations based on differential gene expression using Gene Set Enrichment Analysis (GSEA), we systematically combined publicly available gene expression datasets with our own MPM data in order to identify candidate targets for MPM therapy. RESULTS: We identified enrichment of target binding sites for the miR-17 and miR-30 families in both MPM tumors and cell lines. RT-qPCR revealed that members of both families were significantly downregulated in MPM tumors and cell lines. Interestingly, lower expression of miR-17-5p (P = 0.022) and miR-20a-5p (P = 0.026) was clearly associated with epithelioid histology. We interrogated the predicted targets of these differentially expressed microRNA families in MPM cell lines, and identified KCa1.1, a calcium-activated potassium channel subunit alpha 1 encoded by the KCNMA1 gene, as a target of miR-17-5p. KCa1.1 was overexpressed in MPM cells compared to the (normal) mesothelial line MeT-5A, and was also upregulated in patient tumor samples compared to normal mesothelium. Transfection of MPM cells with a miR-17-5p mimic or KCNMA1-specific siRNAs reduced mRNA expression of KCa1.1 and inhibited MPM cell migration. Similarly, treatment with paxilline, a small molecule inhibitor of KCa1.1, resulted in suppression of MPM cell migration. CONCLUSION: These functional data implicating KCa1.1 in MPM cell migration support our integrative approach using MPM gene expression datasets to identify novel and potentially druggable targets.

A proteomics-based approach identifies secreted protein acidic and rich in cysteine as a prognostic biomarker in malignant pleural mesothelioma.

BACKGROUND: We aimed to identify prognostic blood biomarkers using proteomics-based approaches in malignant pleural mesothelioma (MPM). METHODS: Plasma samples from 12 MPM patients were used for exploratory mass spectrometry and ELISA analyses. The significance of secreted protein acidic and rich in cysteine (SPARC) was examined in sera from a Dutch series (n=97). To determine the source of the circulating SPARC, we investigated SPARC expression in MPM tumours and healthy controls, as well as the expression and secretion from cell lines and xenografts. RESULTS: Secreted protein acidic and rich in cysteine was identified as a putative prognostic marker in plasma. Validation in the Dutch series showed that the median survival was higher in patients with low SPARC compared with those with high SPARC (19.0 vs 8.8 months; P=0.01). In multivariate analyses, serum SPARC remained as an independent predictor (HR 1.55; P=0.05). In MPM tumour samples, SPARC was present in the tumour cells and stromal fibroblasts. Cellular SPARC expression was higher in 5 out of 7 cell lines compared with two immortalized mesothelial lines. Neither cell lines nor xenograft tumours secreted detectable SPARC. CONCLUSIONS: Low circulating SPARC was associated with favourable prognosis. Secreted protein acidic and rich in cysteine was present in both tumour cells and stromal fibroblasts; and our in vitro and in vivo experiments suggest that stromal fibroblasts are a potential source of circulating SPARC.

Survival of Australian lung cancer patients and the impact of distance from and attendance at a thoracic specialist centre: a data linkage study.

BACKGROUND: Lung cancer patients have better survival when treated in thoracic surgical (specialist) centres. AIMS: To determine whether outcome of non-small cell lung cancer (NSCLC) patients is poorer with increasing distance to the nearest accessible specialist hospital (NASH). METHODS: We linked cancer registry, hospital and death records of 23,871 NSCLC patients; 3240 localised, 2435 regional and 3540 distant stage patients hospitalised within 12 months of diagnosis were analysed. Distance from patients' residences to the NASH was measured using geographical coordinates. Cox proportional hazards models examined predictors of NSCLC death. RESULTS: Having a resection of the cancer, which admission to a specialist hospital made more likely, substantially reduced hazard of NSCLC death. Distance influenced hazard of death through both these variables; a patient was less likely to be admitted to a specialist hospital than a general hospital and less likely to have a resection the further they lived from the NASH. However, patients who lived distant from the NASH and were admitted to a specialist hospital were more likely to have a resection and less likely to die from NSCLC than patients admitted to a specialist hospital and living closer to the NASH. These patterns varied little with lung cancer stage. CONCLUSIONS: NSCLC outcome is best when patients are treated in a specialist hospital. Greater distance to the NASH can affect its outcome by reducing the likelihood of being treated in a specialist hospital. Research is needed into patient and health service barriers to referral of NSCLC patients for specialist care.

What factors are predictive of surgical resection and survival from localised non-small cell lung cancer?

OBJECTIVE: To investigate opportunities to reduce lung cancer mortality after diagnosis of localised non-small cell lung cancer (NSCLC) in New South Wales through surgical resection. DESIGN, PATIENTS AND SETTING: In this cohort study, resection rates and lung cancer mortality risk were explored using multivariate logistic regression and competing risk regression, respectively. Data for 3040 patients were extracted from the NSW Central Cancer Registry for the diagnostic period 1 January 2003 to 31 December 2007. Subset analyses for patients at low surgical risk indicated resection rates and outcomes under ideal circumstances. MAIN OUTCOME MEASURES: Resection rates and lung cancer mortality. RESULTS: The resection rate in NSW was estimated to be between 38% and 43%, peaking at 59% by local health district (LHD) of residence. Not having a resection was associated with older age, lower socioeconomic status, lack of private health insurance, and residence by LHD. Adjusted 5-year cumulated probabilities of death were 76% in absence of resection, 30% for wedge resection, 18% for segmental resection, 22% for lobectomy and 45% for pneumonectomy. Of 255 "low surgical risk" patients, 71% had a resection. Those not receiving a resection had a higher probability of death (adjusted subhazard ratio, 14.1; 95% CI, 7.2-27.5). If the low overall resection rate of 38%-43% in NSW were increased to 59% (the highest LHD resection rate), the proportion of all patients with localised NSCLC dying of NSCLC in the 5 years from diagnosis would decrease by about 10%, based on differences in probabilities of death by resection estimated in this study. CONCLUSIONS: Potential exists to reduce deaths from NSCLC in NSW through increased resection.

Prognostic coronary surgery in a case of malignant mesothelioma previously managed with trimodality treatment.

We report a case of malignant pleural mesothelioma treated with trimodality treatment. At three years after the extrapleural pneumonectomy, coronary artery revascularisation surgery for NSTEMI was performed in view of favourable long term prognostic and survival outcome. Five years following pleuropneumonectomy there is no clinical or radiological evidence of mesothelioma and the patient remains free of cardiac symptoms.

Testing for ALK rearrangement in lung adenocarcinoma: a multicenter comparison of immunohistochemistry and fluorescent in situ hybridization.

Rearrangements of anaplastic lymphoma kinase (ALK) gene in non-small cell lung cancer (NSCLC) define a molecular subgroup of tumors characterized clinically by sensitivity to ALK tyrosine kinase inhibitors such as crizotinib. Although ALK rearrangements may be detected by reverse transcriptase-PCR, immunohistochemistry or fluorescence in situ hybridization (FISH), the optimal clinical strategy for identifying ALK rearrangements in clinical samples remains to be determined. We evaluated immunohistochemistry using three different antibodies (ALK1, 5A4 and D5F3 clones) to detect ALK rearrangements and compared those with FISH. We report the frequency and clinicopathologic features of lung cancers harboring ALK translocations in 594 resected NSCLCs (470 adenocarcinomas; 83 squamous carcinomas, 26 large cell carcinomas and 15 other histological subtypes) using a tissue microarray approach. We identified an ALK gene rearrangement in 7/594 cases (1%) by FISH and all anti-ALK antibodies correctly identified the seven ALK-positive cases (100% sensitivity), although the intensity of staining was weak in some cases. These data indicate that the use of antibodies with high sensitivity and avidity to ALK may provide an effective pre-screening technique to complement the more expensive and labor-intensive approach of ALK FISH testing.

Aquaporin 1 is an independent prognostic factor in pleural malignant mesothelioma.

BACKGROUND: Malignant mesothelioma (MM) is an aggressive cancer of serosal membranes, mostly pleura. It is related to asbestos exposure and its incidence in most industrialized countries is projected to remain stable or to increase until 2020. Prognosis remains poor. Clinical prognostic scoring systems lack precision. No prognostic tissue markers are available. Aquaporin 1 (AQP1) is a cell membrane channel involved in water transport, cell motility, and proliferation. A blocker and an agonist are available. METHODS: Two independent cohorts of MM were studied. Cohort 1 consisted of 80 consecutive patients who underwent radical surgery (extrapleural pneumonectomy [EPP]). Cohort 2 included 56 conservatively managed patients from another institution. Clinical information was obtained from files. Diagnoses were histologically verified. Immunohistochemical labeling for AQP1 was performed on tumor tissue and the percentage of positive cells was scored. RESULTS: We demonstrated expression of AQP1 in normal and neoplastic mesothelium at the apical aspect of the cell, in keeping with a role in water transport. For both cohorts, expression of AQP1 by ≥50% of tumor cells was associated with significantly enhanced survival (9.4 months vs 30.4 months in EPP patients and 5 months vs 15 months in conservatively treated patients). This was independent of established prognostic factors, including histologic subtype, pathologic stage, sex, and age at time of diagnosis. CONCLUSION: Expression of AQP1 correlated significantly with prognosis in MM, irrespective of treatment or established prognostic factors. Immunohistochemical labeling for AQP1 should be included in the routine histopathologic workup. An agonist or blocker may become useful for treatment.

Surgical management of melanoma lung metastasis: an analysis of survival outcomes in 292 consecutive patients.

BACKGROUND: The role of surgical resection of melanoma lung metastases (MLM) remains controversial. Some authorities advocate an aggressive surgical approach, while others recommend a conservative strategy. This study sought to identify the clinicopathologic and predictors of outcome after surgical management of MLM in a large series of melanoma patients from a single institution. METHODS: All patients undergoing surgical management of MLM between November 1984 and April 2010 were identified and predictors of outcome analyzed. RESULTS: Of the 292 patients eligible for the study, 112 (38%) had previously undergone surgery for nonpulmonary recurrences. Four patients (1%) died within 30 days of surgery for MLM. The median progression-free survival time was 10 months. The median overall survival and 3- and 5-year survival were 23 months [95% confidence interval (CI) 17­30], 41 and 34%, respectively. Metastasis size >2 cm [hazard ratio (HR) 1.4, 95% CI 1.0­1.8, P = 0.03, HR 1.6, 95% CI 1.2­2.2; P = 0.002] and positive surgical margin (HR 1.5, 95% CI 1.2­1.9, P < 0.001; HR 1.4, 95% CI 1.1­1.7, P = 0.003) were independently associated with poorer progression-free survival and overall survival, respectively. The presence of more than one metastasis (HR 1.4, 95% CI 1.1­1.7, P = 0.013) was independently associated with poorer overall survival. CONCLUSIONS: The results support the role of pulmonary metastasectomy in selected patients with MLM. Patients with small (<2 cm) and solitary tumors that can be completely resected with a negative margin are most likely to experience prolonged survival.

Asbestos-related lung cancer: Clinical characteristics and survival outcomes in an Australian cohort seeking workers compensation.

BACKGROUND AND OBJECTIVES: Due to difficulties in identifying sufficient-sized cohorts there remains uncertainty about prognostic and clinical differences that may be unique to asbestos-related lung cancer (ARLC). In this study, we use the Helsinki Criteria to define a group of ex-workers with lung cancer attributable to asbestos exposure and investigate differences that may exist. METHODS: A total of 529 patients seeking workers' compensation for their lung cancer were assigned to either ARLC or the non-ARLC based on parameters defined in the Helsinki Criteria. Clinical and survival details were collected and analyzed. RESULTS: In our study population, ARLC patients were on average older (72.1 ± 7.8) than non-ARLC patients (66.5 ± 10.2, P < 0.001) and were more likely to be diagnosed as a result of incidental findings or screening program (P < 0.001). The groups were similar in terms of clinical characteristics with the only difference being that plaques were more prevalent among ARLC patients (P < 0.001). Differences were observed for median overall survival (OS), ARLC (9 months) and non-ARLC (13 months, P = 0.005), as well for treatment (P = 0.01). After adjusting for age, however, these differences disappeared. CONCLUSIONS: Age at diagnosis, pleural plaques, and asymptomatic presentation were the attributes that we identified as significantly different between asbestos-related cancer and other lung cancers. In this cohort, ARLC patients were older diagnosis and with worse overall survival.

3-Dimensional mesothelioma spheroids provide closer to natural pathophysiological tumor microenvironment for drug response studies.

Traditional studies using cancer cell lines are often performed on a two-dimensional (2D) cell culture model with a low success rate of translating to Phase I or Phase II clinical studies. In comparison, with the advent of developments three-dimensional (3D) cell culture has been championed as the latest cellular model system that better mimics in vivo conditions and pathological conditions such as cancer. In comparison to biospecimens taken from in vivo tissue, the details of gene expression of 3D culture models are largely undefined, especially in mesothelioma - an aggressive cancer with very limited effective treatment options. In this study, we examined the veracity of the 3D mesothelioma cell culture model to study cell-to-cell interaction, gene expression and drug response from 3D cell culture, and compared them to 2D cell and tumor samples. We confirmed via SEM analysis that 3D cells grown using the spheroid methods expressed highly interconnected cell-to-cell junctions. The 3D spheroids were revealed to be an improved mini-tumor model as indicated by the TEM visualization of cell junctions and microvilli, features not seen in the 2D models. Growing 3D cell models using decellularized lung scaffold provided a platform for cell growth and infiltration for all cell types including primary cell lines. The most time-effective method was growing cells in spheroids using low-adhesive U-bottom plates. However, not every cell type grew into a 3D model using the the other methods of hanging drop or poly-HEMA. Cells grown in 3D showed more resistance to chemotherapeutic drugs, exhibiting reduced apoptosis. 3D cells stained with H&E showed cell-to-cell interactions and internal architecture that better represent that of in vivo patient tumors when compared to 2D cells. IHC staining revealed increased protein expression in 3D spheroids compared to 2D culture. Lastly, cells grown in 3D showed very different microRNA expression when compared to that of 2D counterparts. In conclusion, 3D cell models, regardless of which method is used. Showed a more realistic tumor microenvironment for architecture, gene expression and drug response, when compared to 2D cell models, and thus are superior preclinical cancer models.

Summary of prognostic factors and patient selection for extrapleural pneumonectomy in the treatment of malignant pleural mesothelioma.

BACKGROUND: Extrapleural pneumonectomy (EPP) has been shown to improve long-term survival outcomes in selected patients with malignant pleural mesothelioma (MPM). The present study aimed to evaluate potential prognostic factors on overall survival for patients who underwent EPP for MPM and to examine the patient selection process in major referral centers that perform EPP. METHODS: A systematic review of the current literature was performed using 5 electronic databases. Relevant studies with prognostic data on overall survival for patients with MPM treated by EPP were included for review. Two reviewers independently assessed each included study. RESULTS: A total of 17 studies from 13 institutions containing the most updated and complete data on prognostic factors for patients with MPM who underwent EPP were included for review. A number of quantitative, clinical, and treatment-related factors were identified to have significant impact on overall survival. CONCLUSIONS: Patients with nonepithelial MPM and nodal involvement have consistently demonstrated to have a worse prognosis after EPP. Their eligibility as candidates for EPP should be questioned. The preoperative patient selection process currently differs greatly between institutions and should focus on identifying patients with nonepithelial histologic subtypes and nodal involvement to exclude them as EPP surgical candidates in the future.

CDKN2A and MTAP Are Useful Biomarkers Detectable by Droplet Digital PCR in Malignant Pleural Mesothelioma: A Potential Alternative Method in Diagnosis Compared to Fluorescence In Situ Hybridisation.

BACKGROUND: The diagnosis of malignant pleural mesothelioma (MPM) can be difficult, in part due to the difficulty in distinguishing between MPM and reactive mesothelial hyperplasia (RMH). The tumor suppressor gene, CDKN2A, is frequently silenced by epigenetic mechanisms in many cancers; in the case of MPM it is mostly silenced via genomic deletion. Co-deletion of the CDKN2A and methylthioadenosine phosphorylase (MTAP) genes has been researched extensively and discovered to be a highly specific characteristic of MPM. Most studies have used FISH to detect the deletion of CDKN2A and IHC for MTAP as a surrogate for this. In this study, we aim to investigate and validate droplet digital PCR (ddPCR) as an emerging alternative and efficient testing method in diagnosing MPM, by particularly emphasizing on the loss of MTAP and CDKN2A. METHODS: This study included 75 formalin fixed paraffin embedded (FFPE) MPM tissue, and 12 normal pleural tissue and 10 RMH as control. Additionally, primary MPM cell lines and normal pleural samples were used as biomarker detection controls, as established in our previous publication. All FFPE specimens were processed to isolate the DNA, that was subsequently used for ddPCR detection of CDKN2A and MTAP. FFPE samples were also analyzed by fluorescence in situ hybridization (FISH) for CDKN2A and MTAP deletion, and for MTAP IHC expression. Concordance of IHC and ddPCR with FISH were studied in these samples. RESULTS: 95% and 82% of cases showed co-deletion of both MTAP and CDKN2A when determined by FISH and ddPCR respectively. ddPCR has a sensitivity of 72% and specificity of 100% in detecting CDKN2A homozygous loss in MPM. ddPCR also has a concordance rate of 92% with FISH in detecting homozygous loss of CDKN2A. MTAP IHC was 68% sensitive and 100% specific for detecting CDKN2A homozygous loss in MPM when these losses were determined by ddPCR. CONCLUSION: Our study confirms that MTAP is often co-deleted with CDKN2A in MPM. Our in-house designed ddPCR assays for MTAP and CDKN2A are useful in differentiating MPM from RMH, and is highly concordant with FISH that is currently used in diagnosing MPM. ddPCR detection of these genetic losses can potentially be utilized as an alternative method in the diagnosis of MPM and for the future development of a less-invasive MPM-specific detection technique on MPM tumor tissue DNA.

Expression and prognostic significance of cyclin B1 and cyclin A in non-small cell lung cancer.

AIMS: Aberrant expression of cell cycle regulators has been implicated in the pathogenesis of many neoplasms, including non-small cell lung cancer (NSCLC). The aim was to examine the expression and prognostic value of cyclin B1 and cyclin A, key regulators of the G(2)/M checkpoint of the cell cycle, in NSCLC and bronchial precursor lesions. METHODS AND RESULTS: Immunohistochemical expression of cyclin B1 and A was examined in 90 cases of stage I-II primary NSCLC and bronchial precursor lesions using tissue microarrays. Increased cyclin B1 and A expression was found in 40.9 and 58.9% of NSCLC cases, respectively, and was significantly higher in primary NSCLC, lymph node metastases and some bronchial precursor lesions compared with normal bronchial epithelium. Increased expression of cyclin A and cyclin B1 correlated with tumour type, poorly differentiated tumours and male gender. A significant association was found between increased cyclin B1 expression and reduced survival using Kaplan-Meier survival analysis. On multivariate analysis, cyclin B1 was not an independent prognostic factor (P = 0.067). Cyclin A expression was not associated with survival. CONCLUSIONS: Cyclin B1 and cyclin A are aberrantly expressed in NSCLC and some precursor lesions. Cyclin B1, but not cyclin A, shows some promise as a potential prognostic marker in NSCLC.

Transcriptional suppression of the miR-15/16 family by c-Myc in malignant pleural mesothelioma.

MicroRNA downregulation is frequent in malignant pleural mesothelioma (MPM), but the mechanisms responsible for loss of miR-15/16 and miR-193a are yet to be elucidated and were investigated in this study. Copy Number Variation (CNV) of microRNA-coding genes was analyzed in MPM cells by digital droplet PCR (ddPCR) and revealed heterozygous loss of miR-193a and miR-15a/16-1, but no change in miR-15b/16-2. Epigenetic control of microRNA expression was inferred following decitabine and Trichostatin A (TSA) treatment which did not substantially affect microRNA expression. Knockdown of c-Myc expression led to upregulation of SMC4, miR-15b and 16, and to a lesser extent DLEU2 and miR-15a, whereas c-Myc overexpression repressed microRNA expression. Chromatin immunoprecipitation (ChIP) assays confirmed the interaction of c-Myc with the DLEU2 and SMC4 promoters. Tumor microRNA expression was determined in samples from MPM patients, with samples of pleura from cardiac surgery patients used as controls. In tumor samples, a strong correlation was observed between the expression of miR-15b and 16 (R2=0.793), but not miR-15a and 16. Our data suggest that in MPM, the downregulation of miR-15/16 is due to transcriptional repression by c-Myc, primarily via control of the miR-15b/16-2 locus, while miR-193a-3p loss is due to genomic deletion.

High BIN1 expression has a favorable prognosis in malignant pleural mesothelioma and is associated with tumor infiltrating lymphocytes.

OBJECTIVES: A number of key immune regulators show prognostic value in malignant pleural mesothelioma (MPM), but the association between Bridging integrator 1 (BIN1), indoleamine 2,3 dioxygenase 1 (IDO1) and patient outcome has not been investigated. We aimed to determine the expression of BIN1 and IDO1, their association with other markers and impact on overall survival (OS) in MPM. MATERIALS AND METHODS: The expression of BIN1, IDO1, CD3, CD20 and CD68 were evaluated by immunohistochemistry in 67 patients who underwent pleurectomy/decortication. Survival analyses were performed using the Kaplan Meier method and significant biomarkers were entered into a Cox Regression multivariate model, accounting for known prognostic factors such as age, gender, histological subtype, PD-L1 expression and neutrophil-to-lymphocyte ratio. RESULTS: Immune markers were variably expressed in tumor cells, ranging from 0% to 100% for BIN1 (median: 89%), and 0% to 77.5% for IDO1 (median: 0%). Expression of markers of tumor-infiltrating lymphocytes (TILs) and macrophages ranged from 0% to more than 50%. BIN1 expression was high in 35 patients (51%) and was associated with increased OS (median: 12 vs 6 months for high and low BIN1 respectively,p = 0.03). Multivariate analysis showed BIN1 remained an independent prognostic indicator (HR 0.39; 95% CI: 0.18-0.82, p = 0.01). The majority of patients had immune inflamed tumors (77%) and there was a significant association between TILs and BIN1 (p = 0 < 0.01), PD-L1 (p=0.04) and CD68+ macrophages in the tumor (p < 0.01). There were no significant associations between PD-L1 and BIN1 or IDO1. CONCLUSION: High BIN1 expression is a favorable prognostic biomarker and is associated with TILs in MPM.

Prediction modelling using routine clinical parameters to stratify survival in Malignant Pleural Mesothelioma patients undergoing cytoreductive surgery.

INTRODUCTION: Malignant pleural mesothelioma (MPM) is an uncommon cancer with a poor prognosis and heterogeneous survival. Surgery for MPM is offered in some specialist centers to highly selected patients. A previously described classification and regression tree (CART) model stratified survival in unselected MPM patients using routinely collected clinical data. This study aimed to examine the performance of this CART model on a highly selected surgical population. METHODS: Data were collected from subjects undergoing cytoreductive surgery for MPM from specialist centers in Hyõgo, Japan, and Sydney, Australia, between 1991 and 2016. The CART model was applied using the combination of clinical variables to stratify subjects into risk groups (1 through 4); survival characteristics were then compared. RESULTS: Two hundred eighty-nine cases were included (205 from Australia, 84 from Japan). Overall median survival was 34.6 (interquartile range: 17.5-56.1) months; median age was 63.0 (interquartile range: 57.0-67.8) years, and 83.0% (n = 240) were male. There were no clinically meaningful differences between the two cohorts. Survival across the four risk groups was significantly different (p < 0.0001); the model stratified survival well with a Harrell's concordance statistic of 0.62 (95% confidence interval: 0.57-0.66) at 36 months. The group with the longest survival (median, 82.5 months) had: no weight loss, hemoglobin > 153 g/L and serum albumin > 43 g/L at time of referral to the surgical center. CONCLUSIONS: Using routinely available clinical variables, the CART model was able to stratify surgical patients into risk groups with statistically different survival characteristics with fair to good performance. Presence of weight loss, anemia, and low albumin should confer caution when considering surgical therapy for MPM.

Dysregulated Expression of the MicroRNA miR-137 and Its Target YBX1 Contribute to the Invasive Characteristics of Malignant Pleural Mesothelioma.

INTRODUCTION: Malignant pleural mesothelioma (MPM) is an aggressive malignancy linked to asbestos exposure. On a genomic level, MPM is characterized by frequent chromosomal deletions of tumor suppressors, including microRNAs. MiR-137 plays a tumor suppressor role in other cancers, so the aim of this study was to characterize it and its target Y-box binding protein 1 (YBX1) in MPM. METHODS: Expression, methylation, and copy number status of miR-137 and its host gene MIR137HG were assessed by polymerase chain reaction. Luciferase reporter assays confirmed a direct interaction between miR-137 and Y-box binding protein 1 gene (YBX1). Cells were transfected with a miR-137 inhibitor, miR-137 mimic, and/or YBX1 small interfering RNA, and growth, colony formation, migration and invasion assays were conducted. RESULTS: MiR-137 expression varied among MPM cell lines and tissue specimens, which was associated with copy number variation and promoter hypermethylation. High miR-137 expression was linked to poor patient survival. The miR-137 inhibitor did not affect target levels or growth, but interestingly, it increased miR-137 levels by means of mimic transfection suppressed growth, migration, and invasion, which was linked to direct YBX1 downregulation. YBX1 was overexpressed in MPM cell lines and inversely correlated with miR-137. RNA interference-mediated YBX1 knockdown significantly reduced cell growth, migration, and invasion. CONCLUSIONS: MiR-137 can exhibit a tumor-suppressive function in MPM by targeting YBX1. YBX1 knockdown significantly reduces tumor growth, migration, and invasion of MPM cells. Therefore, YBX1 represents a potential target for novel MPM treatment strategies.