MicroRNA-1284 enhances radio-sensitivity in hepatocellular carcinoma cells by regulating SP1

Background: Hepatocellular carcinoma (HCC) is the most common cancer worldwide, with high morbidity and mortality. This study was aimed to explore the role of microRNA-1284 (miR-1284) in radio-sensitivity of HCC cells. Methods: HCC cell lines HepG2 and SMMC-7721 were used in this study and their correspondingly radioresistant cells were established. The mRNA level expression of miR-1284 in these four cells was monitored by quantitative PCR (qPCR). MiR-1284 mimic or control was transfected into cells, and transfected cells viability and radio-sensitivity were measured by Cell Counting Kit-8 (CCK-8) and clonogenic survival assay. Besides, the expression of Sp1 Transcription Factor (SP1) in miR-1284 overexpressed and suppressed cells were determined by qPCR and Western blot. Further, miR-1284 inhibitor and/or small interfering RNA (siRNA) against SP1 were transfected into cells, and transfected cells viability and radio-sensitivity were measured again. Results: Down-regulation of miR-1284 was found in radio-resistant cells (P < 0.001). Overexpression of miR-1284 significantly inhibited cell viability (P < 0.05 or P < 0.01) and enhanced radio-sensitivity (P < 0.05 or P < 0.01). SP1 was negatively regulated by miR-1284 (P < 0.01 or P < 0.001), and knock-down of SP1 significantly abolished the regulatory effects of miR1284 suppression on cell viability (P < 0.05 or P < 0.01) and radio-sensitivity (P < 0.05 or P < 0.01). Conclusion: Overexpression of miR-1284 enhanced the radio-sensitivity of HCC in vitro. Of note, SP1 might be involved in the regulatory effects of miR-1284 on HCC cells radio-sensitivity.