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DISCOVERY OF MICRORNA-REGULATED PROTEIN PATHWAY AS BIO-MARKER FOR LUNG CANCER Nilubon Kurubanjerdjit1,*, Nattakarn Iam-On1 and Ka-Lok Ng2,3 1 School of Information Technology, Mea Fah Luang University, Chiang Rai 57100, Thailand Department of Biomedical Informatics, Asia University, Taichung 41354, Taiwan 3 Department of Medical Research, China Medical University Hospital, China Medical University, Taichung, Taiwan 40402 *e-mail [email protected]; [email protected] 2 Abstract Diagnosis of lung cancer at its early stage is important for improving the effect of patient’s treatment and survival rate. MicroRNAs play crucial roles in human cancers, it was know that they play an important role in the regulation of cell growth, differentiation, and apoptosis. However, their role in cancer is not yet fully discovered and understood. The identification of microRNA mechanism in cancer may provide important information of genetic regulation in tumorigenesis. In this work, our results suggested that microRNAs may act as potential biomarkers for lung cancer, by investigating their downstream regulatory pathways. The microRNA-regulated protein pathways were constructed by integrating two pieces of our previous research information; which are (i) lung cancer-associated proteins and (ii) microRNA-target gene interactions. The pathways may insight reveal crucial mechanisms of microRNA on their downstream proteins in lung cancer, and ultimately become valuable therapeutic information for drug discovery or being key information for alternative treatment discovery for lung cancer patient. Keywords: microRNA, protein-protein interaction, lung cancer, machine learning, Naïve Bayes, SVM, MCODE, protein pathway, clique percolation clustering Introduction Lung cancer is the leading cause of cancer-related deaths all over the world with a very high mortality rate. The 5-year overall survival rate highly correlates with the time of diagnosis and varies between 60-80% in clinical stage I to only 1% in clinical stage IV. Unfortunately, lung cancer is mostly diagnosed in late stages (Calin et al. 2002). There are two categories of lung cancer which are small-cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC) (Takamizawa et al. 2004). MicroRNAs are a class of naturally occurring; small non-coding RNA endogenous molecules of ribonucleic acid found in eukaryotic cells (Bartel 2004), up or down-regulation of microRNA affect their target gene expression. The translational inhibition by microRNA is a major mechanism in animal systems. A number of microRNA is known for functioning in diverse processes related to cancer formation such as cell proliferation, cell death, differentiation, and immunity (He and Hannon 2004). MicroRNA cancer biology is a major research over the past decades. Many works have demonstrated the crucial role of microRNAs in cancer though controlling expression of their target genes to facilitate tumour growth, invasion and immunity system (Ebert and Sharp 2012). Alterations of the microRNA expression have been associated with changes of cancer cells making microRNAs currently is one of the most significant molecules involved in cancer research (Leidinger et al. 2012). The work of Calin et al. (Calin et al. 2002) indicates for the first time a correlation of microRNA degradation and cancer. Subsequently, there are significant reports about microRNAs expression changes and cancer from many research works. The first finding of microRNA expression inducing lung cancer was revealed by Takamizawa et al. (Takamizawa et al. 2004). This work confirmed that reduced microRNA let-7 expression was correlated with a shorter post-operative survival. The work of Xiong et al. (Xiong et al. 2011) also reports that let-7 targets BCL-2, which is a proto-oncogene, involves in regulation of apoptosis and its expression inhibits the growth of A549 cells. Furthermore, the work of squeal-Kerscher et al. (squela-Kerscher et al. 2008) confirms that let-7 reduces lung cancer tumor cell growth in immunodeficient mice. There are many reports on other microRNAs that are deregulated in lung cancer cell lines such as, miR-21, its expression involves negative prognostic factor for the overall survival rate in non-small cell lung cancer patients (Markou et al. 2008). Besides, Volinia et al. (Volinia et al. 2012) found that the down-regulation of let-7d, miR-210 and miR-221 in ductal carcinoma in situ while they were up-regulated in the invasive transition. The work of Yanaihara et al. (Yanaihara et al. 2006) identified 43 microRNAs that were differentially expressed in microarrays between normal lung and non-small-cell lung cancer (NSCLC) pairs. Moreover, Yang et al. (Yang et al. 2010) reported that miR-30, miR-7i and miR-126 significantly down-regulated in squamous cell lung cancer. The recent study (Izzotti 2010) report that microRNAs expression changes induced by cigarette smoke may be prevented by N-acetylcysteine, oltipraz, indole-3-carbinol, 5,6-benzoflavone, phenethyl isothiocyanate and budesonide. MicroRNA expression patterns are potential prognostic tool, the knowledge on microRNA roles as tumor suppressor or activator component in cancer will be a valuable discovery to develop microRNA-based therapeutic treatment. Nowadays, computational algorithms to detect microRNA and their potential targets have been developed such as miRanda (Enright et al. 2003; John et al. 2004), TargetScan (Bartel 2009), and PITA (Kertesz et al. 2007). Multiple factors are introduced to identify microRNA target genes such as complementarily of different regions on microRNAs, binding site conservation and also target sites accessibility. Different predictive algorithms are based on different factors; therefore, integrating diverse algorithms may improve target prediction. MiRanda is an algorithm written in C for finding target genes for microRNAs. This algorithm was developed at the Computational Biology Center of Memorial Sloan-Kettering Cancer Center. MiRanda identifies microRNA-target genes based on sequence complementarily and conservation of target sites; whereas, PITA predicts microRNA-target gene by calculate the free energies of RNA-RNA duplexes, PITA gives matching scores to multiple biding sites, therefore, optimal combination of different algorithms may improve the prediction performance. Clique percolation clustering (Palla et al. 2005) is a well-known approach for analysing the overlapping community structure of networks by building up communities from k-cliques which are fully connected sub-graphs of k nodes. Any two k-cliques are adjacent if they share k-1 common nodes. A k-clique community is constructed by merging all possible adjacent kcliques. The advantage of this approach is that it allows overlaps between the communities that can be applied to discover significant proteins that involve in more than one community. In this study, microRNA-regulated protein interaction pathways were constructed in order to observe the roles of microRNA in lung cancer by integrating two pieces of information from previous works, which are i) lung cancer-associated proteins (Kurubanjerdjit et al. 2015) and ii) microRNA target genes of lung cancer (Kurubanjerdjit et al. 2016). Currently, there is growing number of evidence reporting that microRNAs polymorphisms associate with drug metabolism and resistance. Furthermore, differentially expression of microRNA plays crucial roles in sensitivity level of chemotherapeutic agents in lung cancer (Gong et al. 2014). Therefore, the drug target is integrated into the microRNA-regulated protein interaction pathways to reveal relation of microRNA and drug for lung cancer. Initially, the novel lung cancer–associated proteins based on MCODE clustering algorithm (Bader and Hogue 2003) were discovered, then enrichment analysis was performed to identify biological process and pathways that related to lung cancer formation. Secondly, an approach to identify microRNA target gene in lung cancer was introduced by adopting prediction scores from miRanda and PITA algorithms, then classification models were implemented to make the final prediction. It is expected that this current study may provide insight for the regulation of microRNA and its downstream protein interactions observed in lung cancer to reveal the role of microRNA on biological processes related lung cancer. To construct microRNA-regulated protein pathways, clique percolation clustering is adopted to discover densely connected protein-protein interaction is referred to as a community which is a functional module. Furthermore, the target drug of microRNA-related proteins also observed in this study to explore microRNA-drug target interaction. Methodology Data Sources 1. MCODE-Clustering on protein-protein interaction A collection of experimentally confirmed lung cancer proteins was obtained from two resources, i.e., Online Mendelian Inheritance in Man (OMIM) and Lung Cancer Database (HlungDB) (Yanaihara 2006). Experimentally confirmed human protein-protein interactions (PPI) were obtained from BioGrid (Database of protein and genetic interactions). The OncoProtein (OCP) and Tumor Suppressor Protein (TSP) data are derived from the following three databases: (1) Tumor Associated Gene database of Taiwan national Cheng Kung University (http://www.binfo.ncku.edu.tw/TAG/), (2) Memorial Sloan-Kettering Cancer Center (https://www.mskcc.org/) and (3) National Yang Ming University. This research collected 656 OCP and 1,024 TSP. 2. MicroRNA-target genes Prediction The predicted lung cancer genes list was obtained from MCODE-Clustering on PPI (Kurubanjerdjit et al. 2015) and their FASTA sequence was obtained from Uniprot (Bairoch 2005). A whole set of human microRNAs sequence was downloaded from mirBase (Sam 2005), list of 39,111 experimentally confirmed microRNA-target pairs were obtained from mirTarBase (Sheng 2014). System Workflow Figure.1 depicts the two steps of this integrating system; firstly, protein clusters were obtaining by using MCODE to extract associated lung cancer protein list which was an input data for the next step. Then, the process of microRNA-target prediction was executed; microRNA-target algorithms (PITA, miRanda) were applied on the clusters found by MCODE. The miRanda and PITA prediction scores were obtained .These scores were used as feature vectors for machine learning classifications to identify the final microRNA-target results. Figure.2 shows the process of protein clustering by MCODE. Initially, a set of PPIs of lung cancer proteins with their protein interacting partners was submitted into AllegroMCODE analyzer in the Cytoscape software (Shannon 2003) to obtain highly interconnected clusters with their score and ranked in a network. Then, the clusters with their complex score over 1.5 and clusters associated by greater than 50% of lung cancer proteins were filtered out to be determined. Besides, enrichment analysis was performed using DAVID (Huang et al. 2009) with the p-value of 0.005. Then, the top five biological processes or KEGG pathways related to cancer formation with the highest rank of p-value were investigated, and finally, we inferred lung cancer-related TSP and OCP based on the PPI assumption, that is, if a protein X interacts with a cancer protein (TSP or OCP), it is very likely that X may function as cancer protein (Kurubanjerdjit et al. 2015). Figure 1. The system flowchart of current study. Figure 2. Protein Clustering by MCODE. Figure.3 is a system flowchart of microRNA-target prediction. Initially, a training set was generated by inputting experimentally confirmed microRNA sequences and their target FASTA sequences into PITA and miRanda to get the prediction scores. The microRNAtarget pairs that satisfied these two algorithms were filtered as a positive set. A negative set is the pairs that satisfied those two algorithms with the positive set subtracted. Secondly, a test set was prepared by the two predictors. A whole set of microRNAs sequences and a set of cancer associated genes, where FASTA sequences were submitted into predictors. The microRNA-target pairs with two prediction scores that satisfied the predictors were extracted to be the test set. Thirdly, Naïve Bayes and Support Vector Machine (SVM) (Cortes and Vapnik 1995) were selected to classify the final prediction results. The training set was submitted into these two classifiers with optimum parameter setting in order to build up the classification models. Next, the test set was submitted to the two classifiers models to give the final prediction result. Three parameters are required for miRanda execution; threshold score, MFE and scaling factor. In this study, they were set to be 80, 14 kcal/mol and 2.0, respectively. The max-score was observed in this study. Note that, the higher the score is the better binding between microRNAs and their target genes. For PITA, sequence of microRNA and UTR were analysed by default parameter setting. In case of single binding site, the score is given by ΔΔG value; whereas, for multiple binding sites, the scores were determined by the minimum value of their binding. The open-access software RapidMiner (Hofmann and Klinkenberg 2013) was adopted as a tool for classification in this work. Two classification algorithms; Naïve Bayes and Support Vector Machine (SVM) were selected to predict which microRNAs are likely to target which associated lung cancer genes. For Naïve Bayes parameter setting, estimation mode is set to greedy, value of minimum band-width is set to 0.1 and number of kernels is set to 10. There following five parameters setting were used for the SVM classifier; ‘kernel type’ is set to radial, ‘kernel gamma’, ‘kernel cache’, ‘c value’ and ‘convergence epsilon’ are set to 1.0, 200, 0.5 and 0.001, respectively. Once the two classifiers were optimized, they were adopted to evaluate the test set. MicroRNA-target pairs obtained from these two classifiers were integrated and only the pairs that were predicted by the two classifiers were filtered as the final results. The result sets obtained from these two steps were constructed as the putative microRNAregulated protein pathways, the biological processes of microRNAs and their lung cancer protein targets were investigated to infer the roles of microRNAs in lung cancer. Figure 3. MicroRNA-target prediction. Clustering microRNA-regulated proteins-cFinder The two sets of results obtained from previous works; microRNA-target genes and proteinprotein interactions were combined to construct microRNA-regulated protein pathways for major biological processes related to lung cancer; apoptosis, programmed cell death, small cell lung cancer (SCLC), and non-small cell lung cancer (NSCLC). Clique percolation clustering was adopted to construct microRNA-regulated protein pathways. In protein-protein interaction network, a densely connected area is referred to as a cluster that all protein members are likely to function in similar biological process. A set of proteins involved in apoptosis, programmed cell death, SCLC, and NSCLC was inputted into the software, cFinder (Adamcsek et al. 2006) to analyse the network of PPI based on clique percolation clustering approach. MicroRNA-regulated protein pathways with target drugs Exploring the significant drugs for the pathways was performed based on the assumption that the expression of specific microRNA may break novel paths for overcoming lung cancer resistance and the personalised therapy. The Genomics of Drug Sensitivity in Cancer was adopted in this study (http://www.cancerrxgene.org). It is the free accessible online software constructed by Sanger Institute, Cancer Center of Massachusetts general hospital. Results Table I shows the total of seven clusters was obtained from Clique Percolation Clustering. Those clusters compose of microRNAs and their related proteins, two clusters at k equals to 3 in apoptosis, two clusters at k equals to 3 in programmed cell death, one cluster at k equals to 4 in programmed cell death, one cluster at k equals to 3 of SCLC and one cluster at k equals to 4 of NSCLC. Table 1 Target Drug for microRNA-related proteins Cluster ID k Biological Process 1 2 3 4 5 6 7 3 3 4 4 3 3 4 Apoptosis Apoptosis Programmed cell death Programmed cell death Programmed cell death SCLC NSCLC #microRNA #protein 2 3 4 4 1 2 5 3 6 5 10 3 3 4 microRNA-regulated protein pathways in Apoptosis Figure 4 shows the microRNA-regulated protein pathways (community) in apoptosis for clique community with k equals to 3. CFLAR gene is a regulator of apoptosis and clearly found that its related pathways are signaling by GPCR and apoptotic pathway in synovial fibroblasts. Jin et al. (Jin et al. 2014) reported the role of miR-146a in human chondrocyte apoptosis in response to mechanical injury, and may contribute to the mechanical injury of chondrocyte. Furthermore, it was reported that miR-146a,b involved in human dendritic cell apoptosis (Park et al. 2015). The mismatch of oxidized miR-184 with Bcl-xL and Bcl-w is involved in the initiation of apoptosis (Wang et al. 2015). Figure 5 depicts miR-422a with their protein pathway, this microRNA is found by X that it plays an important role in colorectal cancer (Faltejskova et al. 2012). MYC is widely known as a crucial regulator of cell cycle progression, apoptosis and cellular transformation. MiR34c is reported by (Catuogno et al. 2013) that it markedly increased resistance to paclitaxelinduced apoptosis. Mir-346 is reported that it up-regulates AGO2 protein expression to augment the activity of other microRNAs and contributes to cervical cancer cell malignancy(Guo et al. 2015). Figure 4. microRNA-regulated protein pathway in apoptosis (k=3). Figure 5. microRNA-regulated protein pathway in apoptosis (k=3). microRNA-regulated protein pathway in program cell death Figure 6 and Figure 7 display miR-520c-3p and their regulated protein pathway, it was found that overexpression of miR-520c-3p dramatically inhibited the proliferation, cell cycle progression, invasion, and migration of gastric cancer, while down-regulation promoted these properties (Li et al. 2014). Consistently, the report from Jie (Jie 2015) also indicates that this microRNA inhibits proliferation, apoptosis in NSCLC. Figure 8 shows the regulation of miR-326 in programmed cell death. The work of Wang (Wang 2013) indicated miR-326 functions as a tumor suppressor, the down-regulation of miR-326 may have potential value for predicting clinical outcomes in glioma patients with high pathological grades. This suggests that miR-326 is an important candidate tumour suppressor, and its down-regulated expression may contribute to glioma progression. Figure 6. microRNA-regulated protein pathway in cell death (k=4). Figure 7. microRNA-regulated protein pathway in cell death (k=4). Fig 8. microRNA-regulated protein pathway in cell death (k=3). microRNA-regulated protein pathway in SCLC and NSCLC Figure 9 depicts miR-590-3p pathway. This microRNA promotes cell proliferation and invasion in T-cell acute lymphoblastic leukaemia by inhibiting RB1 (Miao 2016). Figure 10 shows miR-217 pathway, it functions as tumour suppressor gene and correlates with cell resistance to cisplatin in lung cancer (Guo et al. 2014). Figure 9. microRNA-regulated protein pathway in SCLC (k=3). Figure 10. microRNA-regulated protein pathway in NSCLC (k=4). microRNA pathways with their target drugs Proteins in each microRNA-regulated pathway were mapped with their drug interaction from DrugBank database (David et al. 2008) Table II depicts drugs, drug targets, and interacting microRNAs found in our study. It was recorded by National Cancer Institute (NIH: http://www.cancer.gov/about-cancer/treatment/drugs/) that cetuximab is EGFR inhibitor used for the treatment of metastatic colorectal cancer, NSCLC and head and neck cancer. Besides, bupivacaine 0.25% encapsulated by multilamellar liposomes was administered epidurally to a patient suffering pain associated with lung cancer and the effect compared with a plain bupivacaine solution of the same concentration (Lafont et al. 1996). The work of Carmazzi et al. (Iorio et al. 2012) revealed mechanisms of nadroparin-mediated inhibition of proliferation of two human lung cancer cell lines. Furthermore, Inazu et al. (Inazu et al. 2013) identified choline transporter-like protein 1 (CTL1) -mediated choline transport system provides a potential new target for therapeutic intervention in lung cancer. Table II Drug, drug targets and interacting microRNAs. Drug Drug target Interacting microRNA Cetuximab, Etanercept Immune Globulin Human CFLAR miR-146-5p, miR-184 Bupivacaine Carboprost Tromethamine Alprostadil Nadroparin Pseudoephedrine 2,6-Dihydroanthra/1 9-Cd/Pyrazol-6-One Insulin Human Choline, Vitamin C HIPK2, MYC, DAXX, TP73, JUN miR-34c-5p, miR-346 EP300, HIPK2, DAXX, TP73, JUN EP300, HIPK2, MYC, DAXX, TP73, PRKDC, TSC22D3, TBP, UBC miR-422a miR-34c-5p, miR-346 UBC, MYC, JUN, PRKDC, EP300, DAXX, HIPK2, TBP, TP73 miR-422a, miR-34c-5p, miR-345, miR-520c-3p Discussion and Conclusion MicroRNAs are emerging as key components in gene regulatory pathways in human cancers. It is known that their expression patterns are able to use as potential prognostic, diagnostic and treatment methods. One important area for microRNA research is to understand their functions and the relevant signaling pathways in initiation, and then tumors progression and drug-resistance to be able to design. Discovery the roles of microRNA in cancer would be helpful in developing novel technique in microRNA-based therapeutic treatment. In this study, microRNA-regulated protein interaction pathways were constructed by integrating the lung cancer-associated proteins and microRNA target genes from previous research works. Next, microRNA-regulated protein pathways were created based on clique percolation clustering to discover densely PPI interaction regions in apoptosis, programmed cell death, SCLC and NSCLC biological process. Lastly, the drug of microRNA-target protein is observed to explore microRNA-drug target interaction. The approach introduced in this work and also the results should be of value for future studies to reveal the role of microRNAs in cancer study. 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