[Effect of lncRNA HOTAIR on the radiosensitivity of HCCLM3 cells]

Objective: To investigate the effect of down-regulating long non-coding RNA (lncRNA) and HOX transcript antisense RNA (HOTAIR) targeting miR-761 on the radiosensitivity of HCCLM3. Methods: The expression of HOTAIR in liver cancer cells HuH-7, SNU-449, HCCLM3 and normal liver cells L-02 were measured by real-time quantitative PCR. HCCLM3 cells were divided into control, Sh-NC (transfected shRNA negative control), Sh-HOTAIR (transfected HOTAIR shRNA), RAD+Sh-NC (transfected shRNA negative control and irradiated with 8Gy dose), and RAD+Sh-HOTAIR (HOTAIR shRNA was transfected and irradiated with 8Gy dose) group. Apoptosis was detected by flow cytometry, Bcl-2 Associated X Protein (Bx-2), cleaved cysteine-containing Cleaved cysteinyl aspartate specific proteinase 3 (C-Caspase-3) protein expression. Sh-NC, Sh-HOTAIR cells were irradiated with 0, 2, 4, 6, 8 Gy, and plate-clone experiments were used to determine radiosensitivity. Bioinformatics software predicted that miR-761 might be a target gene of HOTAIR, and the luciferase reporter system identified the targeting relationship. The miR-761 inhibitor, HOTAIR shRNA and inhibitor negative control, and HOTAIR shRNA were co-transfected into HCCLM3 cells, respectively. Cell apoptosis and Bax and C-cysteine-containing aspartate proteins were also measured using the above method, as well as the hydrolase-3 protein expression and cell survival fraction. Results: The expression levels of HOTAIR in liver cancer cells HuH-7, SNU-449, and HCCLM3 were higher than those in normal liver cells L-02 (1.85±0.12, 2.27±0.23, 2.68±0.15 vs 1.00±0.09, P<0.05). Compared with Sh-NC, the apoptosis rate of Sh-HOTAIR, RAD+Sh-NC cells and Bax, C-Caspase-3 protein levels are higher [Apoptotic rate: (13.47±1.32)%, (12.84±1.19)% vs (2.98±0.27)%; Bax protein: 0.74±0.08, 0.72±0.06 vs 0.42±0.06; C-Caspase-3 protein: 0.56±0.06, 0.54±0.08 vs 0.25±0.04, all P<0.05]. Compared with Sh-HOTAIR and RAD+Sh-NC, RAD+Sh-HOTAIR cell apoptosis rate and Bax, C-Caspase-3 protein levels are higher [apoptosis rate:(22.57±2.36)% vs (13.47±1.32)%, (12.84±1.19)%, Bax protein: 0.99±0.11 vs 0.74±0.08, 0.72±0.06, C-Caspase-3 protein: 1.03±0.12 vs 0.56±0.06, 0.54±0.08,all P<0.05]. Compared with Sh-NC, Sh-HOTAIR cells had lower survival scores and higher radiosensitivity (P<0.05). HOTAIR targets negative regulation of miR-761 expression. Compared with cells co-transfected with inhibitor negative control and HOTAIR shRNA, cells co-transfected with miR-761 inhibitor and HOTAIR shRNA had lower apoptosis rate after radiation treatment [(10.24±1.32)% vs (21.84±2.01))%], Bax (0.50±0.06 vs 1.01±0.10) and C-Caspase-3 protein (0.56±0.07 vs 1.05±0.14) had lower expression and higher cell survival scores (all P<0.05). Conclusion: Down-regulating lncRNA HOTAIR targets miR-761 to increase the radiosensitivity of HCCLM3.