Abstract
Simple SummaryCigarette smoke is a major carcinogen that causes lung cancer and induces DNA methylation. DNA methylation regulates the expression of microRNA (miRNAs), which are important regulators of cancer biology. However, the association between smoking and miRNAs has not been fully elucidated in smoking-related lung carcinogenesis. In this study, we found that miR-584-5p expression was downregulated with cancer progression using a lung carcinogenesis model cell line. Moreover, we demonstrated that miR-584-5p is downregulated by the methylation of its promoter region and that it suppresses migration and invasion by targeting YKT6 in smoking-related non-small cell lung cancer (NSCLC) cells. Our results provide a better understanding of the underlying changes in miRNA expression in smoking-related lung carcinogenesis and suggest that miR-584-5p is a potential molecular biomarker for smoking-related NSCLC.Cigarette smoke (CS) affects the expression of microRNAs (miRNAs), which are important regulators of gene expression by inducing DNA methylation. However, the effects of smoking on miRNA expression have not been fully elucidated in smoking-related lung carcinogenesis. Therefore, in this study, to investigate the change of miRNA expression pattern and to identify tumor suppressor miRNAs by smoking in lung carcinogenesis, we used lung carcinogenesis model cell lines that, derived from a murine xenograft model with human bronchial epithelial cells (BEAS-2B), exposed CS or not. The microarray analysis revealed that miR-584-5p expression was downregulated with cancer progression in lung carcinogenesis model cell lines. We confirmed by pyrosequencing that the methylation level of the miR-584-5p promoter increased with cancer progression. In vitro and in vivo experiments showed that miR-584-5p suppressed migration and invasion in non-small cell lung cancer (NSCLC) cells by targeting YKT6. Furthermore, we showed that high level of YKT6 was associated with a poor survival rate in NSCLC patients with a history of smoking. These results suggest that miR-584-5p acts as a tumor suppressor and is a potential molecular biomarker for smoking-related NSCLC.
Highlights
Lung cancer (LC) is one of the most common cancers worldwide [1,2] and is classified into two main categories: small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC)
We found that miR-584-5p expression was significantly downregulated in the lung tissue of patients with smoking-related lung cancer compared to adjacent normal tissues (GSE74190 and GSE19945) (Figure 1F)
We showed that miR-5845p expression is regulated by methylation in lung carcinogenesis model cell lines and smoking-related NSCLC cells
Summary
Lung cancer (LC) is one of the most common cancers worldwide [1,2] and is classified into two main categories: small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC). Smoking is known to contribute to carcinogenesis by causing epigenetic changes, such as DNA methylation and histone modification [8]. The DNA methylation of promotor regions regulates gene expression by suppressing the transcription of protein-coding genes and microRNA-coding genes [9]. DNA methylation of the promoter regions of tumor suppressor genes can contribute to tumor formation [11,12]. MicroRNAs (miRNAs) are small non-coding RNAs that regulate target gene expression by binding to complementary bases in the 30 untranslated region (UTR) of their target mRNAs [14,15]. No prior studies have examined miRNA expression pattern in lung carcinogenesis due to smoking. We analyzed changes in the miRNA expression pattern and degree of methylation using a lung carcinogenesis model cell line (Table 1).
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