Abstract
tRFs and tiRNAs (tRNA-derived fragments) are an emerging class of small noncoding RNAs produced by the precise shearing of tRNAs in response to specific stimuli. They have been reported to regulate the pathological processes of numerous human cancers. However, the biofunction of tRFs and tiRNAs in the development and progression of papillary thyroid cancer (PTC) has not been reported yet. In this study, we aimed to explore the biological roles of tRFs and tiRNAs in PTC and discovered that a novel 5'tRNA-derived fragment called tRF-1:30-Gly-CCC-3 (tRF-30) was markedly down-regulated in PTC tissues and cell lines. Functionally, tRF-30 inhibited the proliferation and invasion of PTC cells. Mechanistically, tRF-30 directly bound to the biotin-dependent enzyme pyruvate carboxylase (PC), downregulated its protein level, interfered with the TCA cycle intermediate anaplerosis, and thus affected metabolic reprogramming and PTC progression. These findings revealed a novel regulatory mechanism for tRFs and a potential therapeutic target for PTC.