Level of tRNA derivative tRF-5026a in serum of breast cancer patients and experimental study of its effect on proliferation, invasion and migration of breast cancer cells / 肿瘤研究与临床

ABSTRACT

Objective:To investigate the level of the transporter RNA (tRNA) derivative tRF-5026a in the serum of breast cancer patients and its value for the diagnosis of breast cancer, and to investigate its effect on the biological functions of breast cancer cells in vitro and the possible mechanisms.Methods:Sixty female breast cancer patients (breast cancer group) hospitalized in Jiangsu Cancer Hospital from January 2016 to February 2019 and 20 healthy women undergoing physical examination during the same period (healthy control group) were retrospectively selected. The relative expression of serum tRF-5026a in the study subjects was detected by real-time quantitative polymerase chain reaction (RT-qPCR). The receiver operating characteristic (ROC) curve of serum tRF-5026a level for the diagnosis of breast cancer was drawn with pathological diagnosis as the gold standard. tRF-5026a mimics (tRF-5026a group) and negative control sequences (negative control group) were transiently transfected into MCF-7 and BT549 cells by lipofectamine method; CCK-8 assay and 5-ethynyl-2-deoxyuridine (EdU) assay were used to detect the ability of cell proliferation in cells of each group; cell apoptosis in cells of each group was detected by flow cytometry; the abilities of cell invasion and migration in cells of each group were detected by Transwell assay; the expressions of epithelial mesenchymal transition-related proteins in cells of each group were detected by Western blotting.Results:The relative expressions of tRF-5026a [ M ( Q1, Q3)] in serum of healthy control group and breast cancer group were 16.58 (6.37, 26.31) and 3.46 (0.32, 9.01), with a statistically significant difference ( Z = -4.27, P < 0.001). ROC curve analysis showed that the area under the curve (AUC) for diagnosis of breast cancer by the relative expression of serum tRF-5026a was 0.820 (95% CI 0.722-0.918), with an optimal cut-off value of 9.082, and the corresponding sensitivity and specificity were 75.0 % and 76.7%, respectively. The apoptosis rates of MCF-7 cells in the tRF-5026a group and the corresponding negative control group were (16.52±0.51)% and (12.28±1.75)%, and the BT549 cells were (13.27±2.18)% and (8.86±0.29)%, the differences were not statistically significant (both P > 0.05). MCF-7 and BT549 cells in the tRF-5026a group had lower proliferative, invasive and migratory abilities than cells in the corresponding negative control group (all P < 0.05). MCF-7 and BT549 cells in the tRF-5026a group had lower protein expressions of N-cadherin, matrix metalloproteinase (MMP)-9 and MMP-3 than cells in the corresponding negative control group. Conclusions:tRF-5026a has low level in the serum of breast cancer patients and it may be an indicator for breast cancer diagnosis. tRF-5026a can inhibit the proliferation, invasion and migration of breast cancer MCF-7 and BT549 cells in vitro, which may be related to the regulation of epithelial mesenchymal transition.