Altered Piwi-RNA Profiles of Peripheral Blood in Bone Metastasis of Non-Small Cell Lung Cancer

Background: PIWI-interacting RNAs (piRNA) are a novel class of non-coding RNAs. They are involved in various pathophysiological activities. However, the expression profiles and functions of piRNAs in the bone metastasis of non-small cell lung cancer are still largely unknown. Methods: Blood samples were collected from patients with non-small cell lung cancer (NSCLC), NSCLC with bone metastasis (BoM) and from healthy volunteers. To evaluate piRNA expression profiles in these samples, high-throughput piRNA microarray was performed. RStudio was used for PCA analysis. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to validate significantly dysregulated piRNAs. To predict the potential functions of dysregulated piRNAs, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed. The mRNA targets of the piRNAs were predicted using TargetScan and miRanda software. The interaction networks between the piRNAs and their targets were constructed using Cytoscape software. Results: A total of 11026 differentially expressed piRNAs were identified, including 134 up-regulated piRNAs and 45 down-regulated piRNAs in NSCLC with bone metastasis (LCBM) vs. non-small cell lung cancer (LC) group and 760 up-regulated piRNAs and 975 down-regulated piRNAs in LCBM vs. healthy volunteers (Ctrl) group with P ≤0.05, fold change ≥1.0. Twenty-four dysregulated piRNA genes with statistically significant differences among all three groups were selected to be validated by qPCR. The qRT-PCR validation confirmed the reliability of the microarray data. The potential targets were predicted by combining with the miRanda and TargetScan software analyses. Through GO and KEGG analysis, these dysregulated piRNAs were found to be potentially involved in NSCLC with BoM pathogenesis. In particular, these pi-RNA might be involved in the transcriptional misregulation and osteoclast differentiation in lung cancer and the bone metastasis. Conclusions: In conclusion, we have identified novel piRNAs that play important functional roles in initiating and progressing of NSCLC with BoM. Bioinformatics analyses suggested that these dysregulated piRNAs may play an important functional role in the tumorigenesis of NSCLC, especially in the BoM. We identified that piR-hsa-16644 is a potential biomarkers and therapeutic target for BoM, and piR-hsa-11510 is strongly associated with EGFR tyrosine kinase inhibitor resistance.