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R. Lin
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OA02 - Novel Targets and Biomarkers in Malignant Pleural Mesothelioma (ID 369)
- Event: WCLC 2016
- Type: Oral Session
- Track: Mesothelioma/Thymic Malignancies/Esophageal Cancer/Other Thoracic Malignancies
- Presentations: 2
- Moderators:L.E. Raez, M. Jakopovic
- Coordinates: 12/05/2016, 11:00 - 12:30, Stolz 2
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OA02.01 - The microRNA-15/16 Family Regulates Tumour Cell Growth via Fibroblast Growth Factor Signals in Malignant Pleural Mesothelioma (ID 5395)
11:00 - 12:30 | Author(s): R. Lin
- Abstract
- Presentation
Background:
Malignant pleural mesothelioma (MPM) is a highly aggressive, asbestos-related malignancy characterized by poor outcome and limited therapeutic options. Fibroblast growth factor (FGF) signals play important roles in mesothelioma cell growth and malignant behavior and their inhibition leads to reduced tumor growth. MicroRNAs (miRNAs) are conserved noncoding RNAs controlling gene expression via translational repression of target mRNAs. The miR-15/16 family is downregulated in MPM and has tumor suppressor functions. Several FGFs/FGFRs are predicted miR-15/16 targets. The aim of this study was to explore the link between the miR-15/16 and the FGF/R family in MPM.
Methods:
Gene and microRNA expression was determined by RT-qPCR or Taqman Low Density Arrays (TLDAs). Mimics were used for restoring microRNA expression. Stimulation or inhibition of FGF signals or bcl-2 was achieved by recombinant FGF2, siRNAs, or small-molecule inhibitors, respectively. A SYBR green-based proliferation assay and colony formation assays were used to monitor effects on cell growth.
Results:
Expression analysis showed a consistent downregulation of target FGF/FGFR genes after transfection with miRNA mimics. Restoration of miR-15/16 led to dose-dependent growth inhibition, which significantly correlated with sensitivity to the specific FGFR1 inhibitor PD166866. Re-expression of microRNAs in combination with FGFR knock-down or pharmacological inhibition resulted in reduced activity, indicating target competition. Combined inhibition of the FGF-axis and bcl-2, another established target of miR-15/16, resulted in enhanced activity. Treatment with recombinant FGF2 further reduced mature as well as pri-microRNA levels and also could prevent/reduce growth inhibition by mimics, but only when added within 24 hours after transfection. TLDA screens after stimulation/inhibition of FGF signals identified regulation of several other miRNAs involved in pathways relevant for tumour growth and aggressiveness.
Conclusion:
Our data shows that the post-transcriptional repression of FGF-mediated signals contributes to the tumour-suppressor function of the microRNA-15/16 family. Impairing hyperactivated FGF signals as well as the anti-apoptotic protein bcl-2 through the restoration of this miRNA family might serve as a novel therapeutic strategy in mesothelioma.
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OA02.05 - Expression of miR-223 in Mesothelioma Xenografts Originates from Stromal Cells in the Tumour Microenvironment (ID 5875)
11:00 - 12:30 | Author(s): R. Lin
- Abstract
- Presentation
Background:
Malignant pleural mesothelioma (MPM) is an aggressive cancer caused by asbestos exposure with limited therapeutic options. Dysregulated microRNAs play an important role in MPM biology and candidate microRNAs have been investigated as diagnostic and prognostic biomarkers or as a potential treatment targets. The role of miR-223 has previously been investigated in MPM tumour cells and was shown to act as a tumour suppressor by regulating cell mobility. Previous research indicated miR-223 to be primarily expressed by myeloid progenitor derived cells during differentiation of granulocytes and monocytes. This suggests miR-223 might have a more significant role in the inflammatory response during tumourigenesis. In this study we aimed to investigate the origin of miR-223 using mesothelioma xenograft and syngraft models.
Methods:
Human and mouse mesothelioma cell line-derived xenograft (MSTO-H211 and H226) and syngraft (AB1) models were established. MicroRNA profiles of xenografts were compared against profiles of their corresponding in vitro cultured cells to determine candidates. RT-qPCR using TaqMan MicroRNA assays was used to validate expression levels of miR-143-3p, miR-214-3p and miR-223-3p in tumour xenografts and syngrafts with those in corresponding cell lines in vitro. Species-specific ddPCR analysis was performed on RNA from xenograft tumours to determine the expression of human and mouse pri-miR-223.
Results:
MicroRNA profiles of xenograft tumours showed significant upregulation (p < 0.05) of miR-143-3p, miR-214-3p and miR-223-3p compared to corresponding in vitro mesothelioma cell lines. Only miR-223 showed significant upregulation in both xenograft and syngraft tumours compared to corresponding in vitro mesothelioma cell lines (>10000-fold increase). Other microRNAs were not significantly different between cell lines and tumours. RNA isolated from xenograft tumours contained significantly more mouse pri-miR-223 than human pri-miR-223 (p < 0.001), with only minimal expression levels of human tumour pri-miR-223 within xenograft tumours.
Conclusion:
Mature miR-223 is significantly overexpressed in xenograft tumours compared to corresponding in vitro mesothelioma cell lines suggesting stromal contribution. Species-specific pri-miRNA confirmed miR-223 is almost exclusively expressed by the mouse stromal cells in xenograft tumours. Ultimately, localising the expression of miR-223 to specific cell types (such as myeloid derived cells) through in situ hybridisation should help identify a more biologically relevant role for miR-223 in the tumour microenvironment.
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P1.05 - Poster Session with Presenters Present (ID 457)
- Event: WCLC 2016
- Type: Poster Presenters Present
- Track: Early Stage NSCLC
- Presentations: 1
- Moderators:
- Coordinates: 12/05/2016, 14:30 - 15:45, Hall B (Poster Area)
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P1.05-021 - circRNAs: Potential Novel Biomarkers for the Early Detection of Lung Cancer (ID 5020)
14:30 - 15:45 | Author(s): R. Lin
- Abstract
Background:
Lung cancer is the leading cancer killer globally. Cancers such as colon, breast, and prostate all have relatively reliable early detection tests. In contrast, lung cancer does not. If caught early, lung cancer has a much better prognosis. Non-invasive or minimally invasive tools to improve early detection of lung cancer represents a critical unmet need. Analysis of the human transcriptome indicates that a mere 2% of the genome corresponds to protein coding transcripts, yet ~ 75% of the genome is transcribed. It is now well established that these non-coding RNAs (ncRNAs) play important regulatory functions within the cell and their expression are often altered in cancer. Circular RNAs (circRNAs) are a species of ncRNAs. They are abundant, conserved and demonstrate cell-type specific expression patterns. Moreover, they are extremely stable with half-life’s greater than 48 hours, are resistant to degradation by RNA exonucleases, and have been shown to play important roles in cancer. Taken together these suggest that circRNAs could potentially be important biomarkers in early lung cancer diagnosis.
Methods:
Total RNAs isolated from a panel of matched normal/tumour NSCLC adenocarcinoma (Stage IA/IB) samples (n=6) were probed for circRNAs using the Arraystar circRNA microarray. Survival was assessed on linear mRNAs with associated circRNAs using KM-Plot.
Results:
Interim analysis of the data has identified n=206 circRNAs with a 2-fold difference in expression between their matched normal vs. tumour counterparts. Principal Component Analysis (PCA) demonstrated a clear separation of the samples (Tumour vs. Normal). Self-Organizing Maps (SOMs) analysis generated distinctive SOMS clusters of circRNAs, while associated linear pathway enrichment for microRNA and transcriptional binding motifs identified several additional potential networks. Moreover, an analysis of linear mRNAs associated with 10 circRNAs with altered expression in adenocarcinomas found that these mRNAs were linked to overall survival, and that the majority were adenocarcinoma specific.
Conclusion:
Altered levels of a number of circRNAs were associated with lung adenocarcinoma. A separate cohort of squamous cell carcinomas is currently being assessed for circRNAs. At present we are validating the expression of these circRNAs in a larger cohort of specimens, and assessing whether or not these are detectable in plasma/serum from the same individuals. Overall, circRNAs may represent novel potential biomarkers for the detection of NSCLC, and may provide additional critical basic knowledge regarding the development and biology of NSCLC.
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P3.03 - Poster Session with Presenters Present (ID 473)
- Event: WCLC 2016
- Type: Poster Presenters Present
- Track: Mesothelioma/Thymic Malignancies/Esophageal Cancer/Other Thoracic Malignancies
- Presentations: 3
- Moderators:
- Coordinates: 12/07/2016, 14:30 - 15:45, Hall B (Poster Area)
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P3.03-002 - Inducible Changes in Cell Morphology and Gene Expression Reflecting the Histological Subtypes of Mesothelioma (ID 5405)
14:30 - 15:45 | Author(s): R. Lin
- Abstract
Background:
Malignant pleural mesothelioma (MPM) represents an aggressive malignancy with dismal prognosis and limited therapeutic options. MPM occurs in three main histological subtypes: epithelioid, sarcomatoid and biphasic, which are characterized by differences in morphological growth pattern, aggressiveness and patient prognosis. However, the mechanisms and causes responsible for the different cell morphologies are poorly understood. Epithelial-mesenchymal transition (EMT) has been implicated in cancer progression and chemoresistance, but its role in MPM is not well understood. Fibroblast growth factor (FGF) signals promote cell growth, survival and aggressiveness in several tumors including mesothelioma. Aim of this study was to characterize growth factor-induced, EMT-like changes with respect to the MPM histological subtypes.
Methods:
Morphological and behavioral changes of treated cell models were analyzed by morphometry, immunoblotting and functional assays. Alterations in gene or microRNA expression were evaluated via qPCR and array hybridization. Pathway enrichment analysis was based on KEGG.
Results:
In several cell lines established from biphasic MPM, treatment with FGF2 and EGF induced morphological changes reminiscent of EMT and aggressive behavior such as scattering, increased migration, proliferation and invasiveness. Inhibition of the fibroblast growth factor receptors (FGFR) or the MAPK axis via small-molecule inhibitors could prevent these changes and, in cell lines with sarcomatoid-like shape, reverse scattering and induce a more epithelioid morphology. Comparable results were obtained using an engineered FGFR1 enabling contactless activation via blue light. Analyses of genes and microRNAs regulated by FGF2 or EGF showed an overlap with previously established EMT markers but also identified several novel potential markers such as MMP1, ESM1, ETV4, PDL1, ITGA6 or BDKRB2. Blocking the FGFR or MAPK pathways resulted in the opposite regulation of these genes. Inhibition of MMP1 via siRNAs or pharmacological inhibitors prevented FGF2-induced scattering and invasiveness. In unsupervised clustering, the gene expression profiles of solvent- or cytokine-treated cells were associated with those of epithelioid and sarcomatoid MPM, respectively. Immunohistochemistry showed an association of MMP1 as well as phospho-ERK with the sarcomatoid part of tissue specimens from biphasic tumors. Pathway enrichment analysis of differentially expressed genes as well as the targets of altered microRNAs after FGF2 treatment showed that the regulated genes are assigned to categories important for cell growth and aggressive behavior.
Conclusion:
Our data characterize FGFR-mediated signals as important players in MPM aggressiveness and the morphological and behavioral plasticity of mesothelioma cells, leading to a better understanding of the link between the MPM histological subtypes and their influence on patient outcome.
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P3.03-007 - miR-137 Acts as a Tumour Suppressor via the Down-Regulation of YB-1 in Malignant Pleural Mesothelioma (ID 5579)
14:30 - 15:45 | Author(s): R. Lin
- Abstract
Background:
Malignant pleural mesothelioma (MPM) continues to increase in incidence worldwide and has limited therapeutic options. MPM displays characteristic changes in gene expression, including noncoding RNAs such as microRNAs, which have potential therapeutic relevance. One such miRNA is miR-137, a tumour suppressor whose promoter region is frequently methylated in other cancers and lies in in a commonly deleted chromosomal region in MPM (1p21-23). A potential role for miR-137 has yet to be investigated in MPM. One known target of miR-137 is YB-1, a multifunctional protein often up-regulated in other aggressive cancers, where elevated YB-1 levels are linked to poor clinical outcomes. This study investigates the causes of miR-137 suppression, the relationship between miR-137 and YB-1, one of its targets, as well as their roles in MPM cell growth and malignant behaviour.
Methods:
Basal expression of miR-137 and YB-1 was determined in 13 MPM cell lines by RT-qPCR and immunoblotting. Cells were treated with 5’Aza-cytidine and RT-qPCR was conducted to link methylation with miR-137 suppression. Copy number variation (CNV) was investigated by ddPCR. Cells were transfected with miR-137 mimic and subsequent YB-1 expression was investigated using RT-qPCR. Proliferation, colony formation and wound-healing assays were conducted after transfection with miR-137 mimics or YB-1-specific siRNAs.
Results:
miR-137 was absent in 4 MPM cell lines (p<0.01) and was up-regulated in response to 5’Aza-cytidine treatment in these lines, as well as other lines with low basal expression. Copy-number loss was evident in 5 cell lines and gain was present in 2. Increasing levels of miR-137 generally inhibited MPM cell migration, proliferation and colony formation. miR-137 mimics significantly down-regulated YB-1 expression, while YB-1 protein was overexpressed in the majority of MPM cell lines, compared to MeT-5A. YB-1 knock-down resulted in dose-dependent growth inhibition over 120 hours, reduced colony formation and also decreased cell migration. Effects were more pronounced in those cell lines showing high YB-1 protein levels.
Conclusion:
Our results show that methylation and CNV are likely to play a role in miR-137 down-regulation in MPM and that miR-137 acts as a tumour suppressor in MPM through at least in part the down-regulation of YB-1. We also demonstrated that YB-1 is commonly overexpressed and plays a role in proliferation and migration. These results imply a direct relationship between miR-137 and YB-1 expression, a biological interaction that may prove a useful target in developing future therapeutic approaches in MPM.
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P3.03-008 - Hypoxia-Induced Changes in microRNA Levels Contribute to Drug Resistance in a 3D Model of Malignant Pleural Mesothelioma (ID 5867)
14:30 - 15:45 | Author(s): R. Lin
- Abstract
Background:
Malignant pleural mesothelioma (MPM) is an aggressive asbestos-related thoracic cancer. Chemotherapy is the most frequent treatment option but almost every patient will be confronted with recurrence of disease and drug resistance. Previous studies have used 3D spheroid cultures to investigate drug response in MPM. We showed that microRNAs are important players in MPM biology and that they contribute to the response of MPM cells to some chemotherapy drugs. In the current study we aimed to investigate the role of microRNAs in the drug resistance of a 3D spheroid model of MPM.
Methods:
MPM cells were grown in standard 2D culture or as 3D spheroids in low adherence round bottom multi-well plates. The structure of the spheroids was confirmed by conventional and scanning electron microscopy. MicroRNA expression was profiled using TaqMan Low Density Arrays. RT-qPCR and droplet digital PCR were used to validate candidate microRNAs. HIF1a expression was examined in MPM spheroids using immunofluorescence staining. Drug cytotoxicity was investigated in both 2D and 3D cultures using standard proliferation assays, and the effect of drugs on gene expression was analysed. MicroRNA mimics and siRNAs were used to determine the influence of microRNA and HIF1a expression on drug resistance.
Results:
In our adapted model of 3D cell growth, MPM cell lines formed spherical 3D structures, in contrast to the donut shapes reported with other models. MPM cells in these spheroids were more resistant to cisplatin and gemcitabine when compared to cells grown in 2D cultures. Immunofluorescence revealed a hypoxic gradient with high HIF1a expression observed in the centre of the spheroids. Spheroids also exhibited a significant up-regulation of miR-210, miR-21, miR-378a, miR-195 and miR-146b, and down-regulation of miR-320b and miR-1225b. Transfecting MPM cells in 2D culture with miR-210 or miR-21 mimics resulted in increased drug resistance, whereas HIF1a knockdown inhibited spheroid formation and decreased drug resistance. Spheroids displayed higher expression of the ABCG2 drug pump, and ABCG2 was also up-regulated in cisplatin and gemcitabine treated MPM cells.
Conclusion:
Our spheroid model revealed a clear impact of hypoxia on gene expression in MPM cells. Hif1a was highly expressed in the hypoxic centre of the spheroids and is an upstream regulator of the microRNAs we found to be differentially expressed. Pharmacologic and genetic modulation of microRNA and HIF1a levels altered drug resistance in MPM cells, suggesting a link between hypoxia, microRNAs and drug resistance in MPM.
