MiR-129-5p enhances the radiosensitivity of thyroid myeloid cell MZ-CRC-1 by inhibiting HMGB1

Abstract

Objective To explore whether MiR-129-5p participates in radiosensitivity of medullary thyroid cell MZ-CRC-1 by inhibiting the gene expression of high mobility group protein B1 (HMGB1). Methods The radioresistant cell line MZ-CRC-1/R was established from MZ-CRC-1. Cell survival fraction was analyzed by colony formation assay. The expressions of miR-129-5p in MZ-CRC-1 and MZ-CRC-1/R cells were detected by qRT-PCR. Cell viability was determined by MTT assay. Cell apoptosis was measured by flow cytometry. Dual-luciferase reporter assay was performed to confirm the relationship between miR-129-5p and HMGB1. Besides, the protein expressions of HMGB1 and p-AKt were evaluated by western blot. Results Compared with that of MZ-CRC-1 cells, the survival fraction of MZ-CRC-1/R cells was significantly increased (t=3.038, 4.330, 4.885, 4.568, P<0.05), the cell viability of MZ-CRC-1/R cells was also increased (t=3.637, 7.734, 11.896, 14.522, P<0.05), and the expression of miR-129-5p(0.26±0.03) was significantly decreased in MZ-CRC-1/R cells(1.00±0.06) (t=19.107, P<0.05). Compared with miR-NC-inhibitor group, cell viability was promoted and cell apoptosis was blocked in the miR-129-5p-inhibitor group (t=5.156, 6.005, 9.649, 8.659, P<0.05). Moreover, miR-129-5p mimic suppressed cell viability and enhanced cell apoptosis after irradiation (t=3.118, 5.034, 6.005, 7.488, 6.362, P<0.05). Overexpression of miR-129-5p inhibited the protein expressions of HMGB1 and p-AKt (t=9.325, 10.614, P<0.05). In addition, HMGB1 depletion rescued cell apoptosis that was reduced by miR-129-5p inhibitor in MZ-CRC-1 cells (t=6.700, P<0.05), while HMGB1 overexpression attenuated the effect of miR-129-5p upregulation on MZ-CRC-1/R cells (t=7.073, P<0.05). Conclusions miR-129-5p increased the radiosensitivity of medullary thyroid-like cell MZ-CRC-1 by inhibiting HMGB1. Key words: Medullary thyroid carcinoma cells; miR-129-5p; HMGB1; Radiosensitivity