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.

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.

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.

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.

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.

The IASLC Mesothelioma Staging Project: Proposals for the M Descriptors and for Revision of the TNM Stage Groupings in the Forthcoming (Eighth) Edition of the TNM Classification for Mesothelioma.

INTRODUCTION: The M component and TNM stage groupings for malignant pleural mesothelioma (MPM) have been empirical. The International Association for the Study of Lung Cancer developed a multinational database to propose evidence-based revisions for the eighth edition of the TNM classification of MPM. METHODS: Data from 29 centers were submitted either electronically or by transfer of existing institutional databases. The M component as it currently stands was validated by confirming sufficient discrimination (by Kaplan-Meier analysis) with respect to overall survival (OS) between the clinical M0 (cM0) and cM1 categories. Candidate stage groups were developed by using a recursive partitioning and amalgamation algorithm applied to all cM0 cases. RESULTS: Of 3519 submitted cases, 2414 were analyzable and 84 were cM1 cases. Median OS for cM1 cases was 9.7 months versus 13.4 months (p = 0.0013) for the locally advanced (T4 or N3) cM0 cases, supporting inclusion of only cM1 in the stage IV group. Exploratory analyses suggest a possible difference in OS for single- versus multiple-site cM1 cases. A recursive partitioning and amalgamation-generated survival tree on the OS outcomes restricted to cM0 cases with the newly proposed (eighth edition) T and N components indicates that optimal stage groupings for the eighth edition will be as follows: stage IA (T1N0), stage IB (T2-3N0), stage II (T1-2N1), stage IIIA (T3N1), stage IIIB (T1-3N2 or any T4), and stage IV (any M1). CONCLUSIONS: This first evidence-based revision of the TNM classification for MPM leads to substantial changes in the T and N components and the stage groupings.

Randomized controlled trial of the role of positron emission tomography in the management of stage I and II non-small-cell lung cancer.

PURPOSE: Positron emission tomography (PET) is a costly new technology with potential to improve preoperative evaluation for patients with non-small-cell lung cancer (NSCLC). There is increasing pressure for PET to be included in standard diagnostic work-up before decisions about surgical management of NSCLC. The resource implications of its widespread use in staging NSCLC are significant. METHODS: A randomized controlled trial was conducted to investigate the impact of PET on clinical management and surgical outcomes for patients with stage I-II NSCLC. The primary hypothesis was that PET would reduce the proportion of patients with stage I-II NSCLC who underwent thoracotomy by at least 10% through identification of patients with inoperable disease. RESULTS: One hundred eighty-four patients with stage I-II NSCLC were recruited and randomly assigned; 92% had stage I disease. Following exclusion of one ineligible patient, 92 patients were assigned to no PET and 91 to PET. Compared with conventional staging, PET upstaged 22 patients, confirmed staging in 61 and staged two patients as benign. Stage IV disease was rarely detected (two patients). PET led to further investigation or a change in clinical management in 13% of patients and provided information that could have affected management in a further 13% of patients. There was no significant difference between the trial arms in the number of thoracotomies avoided (P =.2). CONCLUSION: For patients who are carefully and appropriately staged as having stage I-II disease, PET provides potential for more appropriate stage-specific therapy but may not lead to a significant reduction in the number of thoracotomies avoided.

Isolated melanoma in the lung where there is no known primary site: metastatic disease or primary lung tumour?

Patients with no history of melanoma occasionally present with apparently metastatic melanoma in the lungs, but have no evidence of a primary melanoma. The aims of this study were to investigate the role of surgical resection in the treatment of such patients, and to examine the evidence for a diagnosis of primary pulmonary melanoma in each case. Patients with an unknown primary melanoma who presented with pulmonary disease and subsequently underwent surgical resection were identified from the Sydney Melanoma Unit database. Fifteen patients fulfilled the study criteria. Multiple lesions were present in four. Eight wedge resections and 10 lobectomies were performed. The patients' median survival was 32 months and the 5-year actuarial survival was 42%. This compares with the overall Sydney Melanoma Unit experience of lung resection for melanoma in 83 patients, where the median survival was 19 months and the 5-year survival was 22%. Resection of pulmonary disease in melanoma patients with an unknown primary lesion can result in long-term survival, and even apparent cure. It is possible that some of the patients in this series had primary melanoma of the lung, but this is impossible to prove.

MiR-score: a novel 6-microRNA signature that predicts survival outcomes in patients with malignant pleural mesothelioma.

BACKGROUND: Prognosis of malignant pleural mesothelioma (MPM) is poor, and predicting the outcomes of treatment is difficult. Here we investigate the potential of microRNA expression to estimate prognosis of MPM patients. METHODS: Candidate microRNAs from microarray profiling of tumor samples from 8 long (median: 53.7 months) and 8 short (median: 6.4 months) survivors following extrapleural pneumonectomy (EPP) were validated by RT-qPCR in 48 additional EPP samples. Kaplan-Meier log ranking was used to further explore the association between microRNA expression and overall survival (OS). Binary logistic regression was used to construct a microRNA signature (miR-Score) that was able to predict an OS of ≥20 months. Performance of the miR-Score was evaluated by receiver operating characteristic (ROC) curve analysis and validated in a series of 43 tumor samples from patients who underwent palliative surgery [pleurectomy/decortication (P/D)]. RESULTS: The miR-Score, using expression data of six microRNAs (miR-21-5p, -23a-3p, -30e-5p, -221-3p, -222-3p, and -31-5p), enabled prediction of long survival with an accuracy of 92.3% for EPP and 71.9% for palliative P/D. Hazard ratios for score-negative patients were 4.12 (95% CI: 2.03-8.37) for EPP and 1.93 (95% CI: 1.01-3.69) for P/D. Importantly, adding the miR-Score to a set of clinical selection criteria (histology, age, gender) increased predictive accuracy in the independent validation set from 76.3% for clinical factors only to 87.3%. CONCLUSIONS: This study has identified a novel 6-microRNA signature (miR-Score) that can accurately predict prognosis of MPM patients.

PD-L1 expression is a favorable prognostic factor in early stage non-small cell carcinoma.

OBJECTIVES: Immune checkpoint blockade using inhibitors of programmed death-1 have shown promise in early phase clinical trials in NSCLC and programmed death-ligand 1 (PD-L1) tumoral expression could potentially be a useful predictive marker. Data reporting the prevalence of PD-L1 expression in NSCLC and clinicopathologic associations is very limited. We sought to determine the frequency of PD-L1 expression in NSCLC and investigate associations with clinicopathologic features and patient outcome. MATERIALS AND METHODS: PD-L1 expression was analyzed using immunohistochemistry (Merck; clone 22C3) in 678 stages I-III NSCLC and 52 paired nodal metastases using tissue microarrays. Tumors with ≥50% cells showing positive membrane staining were considered to have high expression of PD-L1. RESULTS: PD-L1 expression of any intensity was identified in 32.8% of cases. High PD-L1 expression was found in 7.4% of NSCLC. Squamous cell carcinomas (8.1%) and large cell carcinomas (12.1%) showed high PD-L1 expression more commonly than adenocarcinomas (5.1%) but this was not statistically significant (p=0.072). High PD-L1 expression was associated with younger patient age and high tumor grade (p<0.05). There was no association with gender, tumor size, stage, nodal status, EGFR or KRAS mutation status. In multivariate analysis, patients with high PD-L1 expression had significantly longer overall survival (p<0.05). CONCLUSIONS: PD-L1 is expressed at high levels in a significant proportion of NSCLC and appears to be a favorable prognostic factor in early stage disease. As there are potential sampling limitations using tissue microarrays to assess heterogeneously expressed biomarkers, and as the results may differ in advanced stage disease, further studies are recommended.

miR-193a-3p is a potential tumor suppressor in malignant pleural mesothelioma.

Malignant pleural mesothelioma (MPM) is an asbestos-induced cancer with poor prognosis that displays characteristic alterations in microRNA expression. Recently it was reported that the expression of a subset of microRNAs can distinguish between MPM and adenocarcinoma of the lung. However, the functional importance of these changes has yet to be investigated. We compared expression of miR-192, miR-193a-3p and the miR-200 family in normal pleura and MPM tumor specimens and found a statistically significant reduction in the levels of miR-193a-3p (3.1-fold) and miR-192 (2.8-fold) in MPM. Transfection of MPM cells with a miR-193a-3p mimic resulted in inhibition of growth and an induction of apoptosis and necrosis in vitro. The growth inhibitory effects of miR-193a-3p were associated with a decrease in MCL1 expression and were recapitulated by RNAi-mediated MCL1 silencing. Targeted delivery of miR-193a-3p mimic using EDV minicells inhibited MPM xenograft tumour growth, and was associated with increased apoptosis. In conclusion, miR-193a-3p appears to have importance in the biology of MPM and may represent a target for therapeutic intervention.

Polymorphous low-grade adenocarcinoma in the lung: a case report.

Although uncommon, it is well recognized that salivary gland-type tumors can occur as primary lung tumors, probably arising from minor salivary-type glands lining the bronchial tree. Polymorphous low-grade adenocarcinoma (PLGA) is a rare tumor that usually originates from oral minor salivary glands. There are only 2 reported cases showing metastasis to the lung; however, a primary lung tumor has not been reported so far. In this report we describe the clinical and pathological features of another case of PLGA involving the lung, but in a patient with no evidence of a previous oropharyngeal primary. While our case probably represents another example of metastatic PLGA to the lung, to our knowledge, it is the first description of a PLGA involving the lung in the absence of a history of a previous primary oral salivary gland tumor.

Fibroblast growth factor receptor 1 (FGFR1) copy number is an independent prognostic factor in non-small cell lung cancer.

Fibroblast growth factor receptor 1 (FGFR1) is an oncogene that can potentially be targeted by tyrosine kinase inhibitors. We aimed to investigate the prevalence and prognostic significance of alterations in FGFR1 copy number in non-small cell lung cancer (NSCLC). FGFR1 status was evaluated by chromogenic silver in situ hybridisation (ISH) in tissue microarray sections from a retrospective cohort of 304 surgically resected NSCLCs and results were correlated with the clinicopathological features and overall survival. High FGFR1 gene copy number (amplification or high-level polysomy) was significantly more frequent in squamous cell carcinomas (SCC) (24.8%) and large cell carcinomas (LCC) (25%) compared to adenocarcinomas (11.3%) (p = 0.01 and p = 0.03 respectively). Among NSCLC there was no significant correlation between FGFR1-positive status and other clinicopathological features including age, gender, smoking history, tumour size, lymph node status, stage, grade, vascular, lymphatic or perineural invasion. FGFR1-positive patients showed a tendency to longer overall survival in univariate analysis (p = 0.14). Multivariate survival analysis using Cox regression model confirmed FGFR1-positive patients had a significant reduction in the risk of death compared to FGFR1-negative patients (HR 0.6; p = 0.02). High FGFR1 gene copy number is a common finding in SCC and LCC and is an independent favourable prognostic factor.

ZIC1 is silenced and has tumor suppressor function in malignant pleural mesothelioma.

INTRODUCTION: Epigenetic inactivation of tumor suppressor genes is involved in the development of malignant pleural mesothelioma (MPM). ZIC1, a potential tumor suppressor gene involved in regulating cell growth and apoptosis, was investigated in MPM cell lines and tumors. METHODS: ZIC1 expression and promoter methylation were evaluated in MPM cell lines and tumor samples by quantitative polymerase chain reaction (PCR), Combined Bisulfite Restriction Analysis, and methylation-specific PCR. ZIC1 was reexpressed in cell lines and functional effects were assessed. miRNA expression was quantified by microarray and reverse transcription quantitative PCR. ZIC1 knockdown and miRNA inhibitors were used to study the relationship between ZIC1 and miRNA expression and confirmed by chromatin immunoprecipitation PCR. RESULTS: ZIC1 expression was low in MPM cells, and was correlated with ZIC1 promoter methylation and reversed upon decitabine treatment. ZIC1 reexpression inhibited proliferation and invasion in MPM cells whereas knockdown enhanced the growth of MeT-5A. In MPM tumor samples ZIC1 expression was either low or undetectable, with promoter methylation observed in 16 of 24 cases. The overexpression of miR-23a and miR-27a was reduced by ZIC1 reexpression, with inhibitors of miR-23a or miR-27a reducing colony formation. miR-23a overexpression was also associated with shorter survival of MPM patients. CONCLUSION: ZIC1 is down-regulated in MPM through promoter methylation and acts as a tumor suppressor through down-regulation of its direct targets miR-23a and miR-27a.