Screening and potential role of tRFs and tiRNAs derived from tRNAs in the carcinogenesis and development of lung adenocarcinoma

Accumulating evidence has indicated that a group of novel molecules, known as transfer RNA (tRNA)-derived fragments (tRFs) and tRNA halves (tiRNAs), which are derived from tRNAs, serve an essential role in numerous types of human disease, in particular solid tumors. However, to the best of our knowledge, the underlying mechanisms of the effect of tRFs and tiRNAs in lung adenocarcinoma have not been reported. The present study aimed to determine the differential expression levels of tRFs and tiRNAs in lung adenocarcinoma and adjacent tissues using a NextSeq system, and further investigated their potential target genes via bioinformatics analysis. Kyoto Encyclopedia of Genes and Genomes signaling pathway and Gene Ontology functional term enrichment analyses were performed to investigate the function of these target genes in the occurrence and development of lung adenocarcinoma. In patients with lung adenocarcinoma, 338 types of tRFs and tiRNAs were detected via sequencing, 284 of which were not previously reported in the tRF database. Compared with the adjacent tissues, 17 types of tRFs and tiRNAs comprising 34 subtypes were found to be abnormally expressed in lung adenocarcinoma tissues, 20 of which were upregulated and 14 downregulated. Reverse transcription-quantitative PCR verification revealed that the expression levels of tiRNA-Lys-CTT-002, tRF-Val-CAC-010 and tRF-Val-CAC-011 were significantly upregulated, while those of tRF-Ser-TGA-005 were downregulated in lung adenocarcinoma tissues. Bioinformatics analysis identified that tRF-Ser-TGA-005 participated in the ‘cellular response to transforming growth factor β stimulus’ and tRF-Val-CAC-010 and tRF-Val-CAC-011 participated in the ‘Hedgehog signaling pathway’. In conclusion, the results of the present study suggested that tRFs and tiRNAs may be closely associated with the pathogenesis and development of lung adenocarcinoma, providing a novel insight for further studies into lung adenocarcinoma.