Micrornas And Their Related Targets Mediated Non-small Cell Lung Cancer Research Of Adverse Outcome And Resistance

Context: MicroRNAs (miRNAs) represent a class of small non-coding RNAs thatregulate the gene expressions at the posttranscriptional level, subsequently controlcrucial physiological processes. Recent evidence demonstrates that some miRNAshave the functions similar to oncogene or tumor suppressors, it may play importantroles in tumorigenesis. MiRNA expression profiles may become useful biomarkersfor cancer diagnostics, prognosis and prediction of response to treatment, and it couldbe a powerful tool for cancer prevention and therapeutics.Objective: To explore the global expression profile of miRNAs in Non Small CellLung Cancer (NSCLC) and its potential relevance to clinicopathologicalcharacteristics and prognosis.Methods: LNA microRNA microarrays were utilized to detect miRNA expressionlevels in eight surgically removed lung carcinoma tissues (LCT) and theircorresponding normal lung tissues (NT). After initial microarray validation byquantitative real-time reverse transcription polymerase chain reaction assays(qRT-PCR), miR-21, miR-143and miR-181a were selected for further study inanother47paired LCTs and matched NTs by qRT-PCR using Taqman microRNAassay.Result: Twenty-seven microRNAs were observed to be deregulated greater than two-fold in LCT compared with NT by microarray. Consistenting with the microarray,the expression level of miR-21by qRT-PCR was significantly higher in tumor tissuesthan in adjacent normal tissues (p=0.026); while miR-143(p=0.000) and miR-181a(p=0.000) were downregulated in LCT. Interestingly, among the47NSCLC cases,low level expression of miR-143was significantly correlated with smoking status(p=0.026), high miR-21expression (hazard ratio,5.993;95%confidence interval,2.518–14.264; p=0.000) and low miR-181a expression (hazard ratio,0.328;95%confidence interval0.142–0.756; p=0.009) were associated with poor survival,independent of clinical covariates, including TNM staging, lymph note status.Conclusion： Our data thus indicating the potential of miR-21, miR-143andmiR-181a as a novel diagnostic or prognostic biomarker for NSCLC. Besides, thesedata will guide further studies of specific microRNAs might become potential targetsfor therapeutic intervention. Context: Recent developments in clinical trials for adjuvant chemotherapy usingplatinum based regimens have proven to prolong survival after surgery of NSCLC.However, the ability of cancer cells to become resistant to platinum remains asignificant impediment to successful chemotherapy, which usually leads to a relapseand worsening of prognosis, even though such treatment is associated with seriousadverse effects. The mechanisms regulating lung cancer resistance to chemotherapyagents are poorly understood and biomarkers which can predict a good outcome fromadjuvant platinum based chemotherapy are required. A better understanding of theprocesses and mechanisms leading to platinum resistance of NSCLC is necessary todevelop effective therapies that can improve the prognosis of patients with this deadlydisease. Recent evidence has indicated that miRNAs are involved in tumor formationand progression by serving as either oncogenes or tumor suppressor genes, as well asby offering resistance to cytotoxic anticancer therapy. Considering the critical role ofmiRNA in cancer, it was hypothesized that miRNAs could also affect the response toplatinum by regulating the biological processes which are relevant to lung cancerchemoresistance.Purpose: To investigate the possible role of microRNAs in the resistance toplatinum based chemotherapy in Non Small Cell Lung Cancer (NSCLC), explore their potential role and find potential biomarkers for prediction of the response toplatinum.Methods: Microarray was employed to compare the expression of miRNAs betweenA549and A549/CDDP cells. The effect of a differently expressed miRNA (miR-21)was examined on the sensitivity of cells to platinumAfter a systematic review ofEnglish language studies of lung cancer-related molecules were pooled; genes wereclassified in three functional groups by gene ontology (GO) analysis. The keymolecules were indentified by establishing lung cancer related networks andpathways. MiR-21targets were predicted by computational method, followed byscreening for matched gene symbols in NCBI human sequences and GO、pathwayand network analysis. MiR-21targets and their network, which are involved in theresistant mechanisms of lung cancer, were obtained by the final integrative analysis.In vitro study such as trasfection and western blot were used to validate some ofpotential targets. Moreover, miR-21expression in NSCLC tumor tissues and matchedplasma sample was also analyzed by Real-time PCR.Results:21miRNAs were deregulated in A549/CDDP. Increased miR-21expression significantly increased the resistance of A549cell to platinum, whereasreduced miR-21decreased the resistance of A549/CDDP cell. In thesystematic-analysis of lung cancer related miR-21-targets analysis,24Hub geneswere identified by overlap calculation, suggesting that miR-21may play an importantrole in the development and progression of lung cancer through JAK/STAT signalpathway, MAPK signaling pathway, Wnt signaling pathway, cell cycle, PPARsignaling pathway, apoptosis pathway and other pathways. Finally, transfection ofA549/CDDP with anti-miR-21increased the expression of PTEN, RECK, FASLGand decreased BCL-2expression. In contrast, pre-miR-21decreased the expression ofPTEN, RECK, FASLG and increased BCL-2in A549. This finding was further validated in the tissue samples of58patients and it was found that miR-21expressionwas significantly increased in platinum based chemotherapy-resistant patients (n=58,p=0.000). And increased miR-21expression was associated with the shorter DFS (p=0.008). Among these58patients,32had the corresponding plasma samples andsimilar tendencies were detected in68.75%patients.Conclusion: Our data suggests that the expression level of miR-21in tumor tissueand plasma might be used as a biomarker to predict adjuvant platinum basedchemotherapy response and disease free survival in patients with NSCLC. Thus, itmay serve as a novel therapeutic target to modulate platinum-based chemotherapy.