Excessive miR-30a-5p increases the radiosensitivity of hepatoma cells by inhibiting GRP78

Abstract

Purpose: To determine the effect of miR-30a-5p on hepatoma cell radiosensitivity and elucidate the underlying mechanism.Methods: Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was used tomeasure miR-30a-5p expression in HepG2 and THLE-3 cells. After 4-Gy X-ray irradiation or miR-30a-5p mimic transfection, the miR-30a-5p level in HepG2 cells was determined using qRT-PCR. Luciferase reporter assay was used to confirm the correlation between miR-30a-5p and glucose-regulated protein 78 (GRP78) levels, while the effects of miR-30a-5p on the viability of HepG2 cells were determined using clone formation and 3-(4,5)-dimethylthiahiazo (-z-y1)-3,5-di-phenytetrazoliumromide (MTT) assays. Apoptotic cells were evaluated by flow cytometry whereas the protein levels of GRP78, B-cell lymphoma-2 (Bcl-2), BCL2-Associated X Protein (Bax), and cleaved-caspase-9 were quantified by immunoblotting.Results: MicroRNA-30a-5p expression was decreased in HepG2 cells but reduced after 4-Gy x-ray treatment, while miR-30a-5p mimic transfection upregulated miR-30a-5p expression (p < 0.05). Cell viability was inhibited after x-ray irradiation or miR-30a-5p mimic transfection and further inhibited by irradiation + miR-30a-5p (p < 0.05). Irradiation or miR-30a-5p transfection triggered cell apoptosis; however, irradiation + miR-30a-5p induced more apoptosis, upregulated Bax and cleaved-caspase-9 expression, and reduced Bcl-2 expression (p < 0.05). MicroRNA-30a-5p also suppressed GRP78 expression.Conclusion: MicroRNA-30a-5p may enhance HCC x-ray radiosensitivity by inhibiting GRP78., and may be useful in developing treatment strategies for HCC patients.