LAUSR

e12000 Background: It has been confirmed that tRNA-derived small RNA fragments (tRFs) participate in various kinds of biological activities. However, the function of tRFs in chemotherapy resistance in breast cancer still remains unclear. The purpose of this study is to elucidate the relation between tRFs expression character and chemotherapy resistance in breast cancer. Methods: Drug sensitivity was validated by using Cell Counting Kit-8 in ADR-sensitive breast cancer cells (MCF-7) and ADR-resistant cells (MCF-7/ADR). Next-generation sequencing technology was conducted to identify differentially expressed tRFs between MCF-7 and MCF-7/ADR breast cancer cell lines; quantitative RT-PCR (qRT-PCR) were used to validate the differentially expressed tRFs in MCF-7 and MCF-7/ADR cell lines and the serums of chemotherapy sensitive and resistant patients. Then the dysregulated tRFs were identified through Gene ontology (GO), Pathway analysis and network analysis. Finally, receiver operated-characteristic curve (ROC) analysis was carried out to assess the predictive power of the dysregulated tRFs as biomarkers for chemotherapy resistance.The growth and sensitivity of breast tumor to Adriamycin were assessed by micro-CT in vivo. Results: There were 588 differentially expressed tRFs between MCF-7 and MCF-7/ADR cell lines (fold change > 2).tRF-2023, which was significantly downregulated in chemotherapeutic resistance breast cancer tissues and cells, could induce the sensitivity of breast cancer cells to Adriamycin both in vivo and in vitro. Bio-informatic analysis showed that tRF-2023 was mainly involved in flavonoid glucuronidation and cellular gluuronidation, and the target genes of tRF-2023 were involved in RNA polymerase, purine and pyrimidine metabolism, and p53 signaling pathway, which might illuminate the function of tRF-2023 in chemotherapy resistance of breast cancer. The result of ROC also showed that tRF-2023 was involved in breast cancer resistance. Conclusions: Our study provides a comprehensive analysis of tRFs in breast cancer resistance. It is helpful in revealing the significance of tRFs during the development of chemotherapy resistance in breast cancer. We also identified that tRF-2023 could be a new potential biomarker and therapeutic target for chemotherapy-resistant breast cancer.