Expression and function of long non-coding RNA epigenetically-induced 1 in hepatocellular carcinoma

Abstract

Objective To observe the expression of long non-coding RNA (lncRNA EPIC1) in hepatocellular carcinoma (HCC) and its effects on the proliferation, invasion and apoptosis of hepatoma cell lines. Methods Real-time quantitative reverse transcriptase-polymerase chain reaction (RT-qPCR) was adopted to detect the expression levels of EPIC1 in 7 cases of HCC tissues and their paracancerous tissues, 5 liver cancer cell lines (HepG2, SK-HEP-1, HuH-7-80, SMMC-7721, SNU-387) and normal human liver cell line (HL-7702). Hep G2 and HuH-7-80 cells were transfected with recombinant lentiviral particles carrying the EPIC1 genes [LV-small interfering RNA (siRNA)] as the experimental group, and Hep G2 and HuH-7-80 cells transfected with negative control lentiviral particles (LV-NC) were used as the control group. The proliferative capacity of HepG2 and HuH-7-80 cells was measured by cell counting kit-8 (CCK-8) proliferation assay after transfection. The invasion capacity of HepG2 and HuH-7-80 cells was examined by Transwell invasion assay. The apoptosis rate of HepG2 and HuH-7-80 cells was detected by flow cytometry. Results The expression level of EPIC1 in HCC tissues (8.77±0.36) was significantly higher than that in their adjacent tissues (2.39±0.45), and the difference was statistically significant (P<0.01). The expression levels of EPIC1 in HepG2, SK-HEP-1, HuH-7-80, SMMC-7721 and SNU-387 cells (7.24±0.81, 3.11±0.35, 5.17±1.12, 4.38±0.48 and 2.69±0.65) was significantly [about (5.61±0.12) and (4.01±0.16) times] higher than that of HL-7702 cells (1.29±0.13), among which HepG2 and HuH-7-80 cells had the highest expression level, and the difference was statistically significant (P<0.01). The proliferative capacity of HepG2 cells in the EPIC1 group with low expression at 24, 48, 72 h (LV-siRNA1: 0.43±0.02, 0.72±0.02, 1.31±0.01, P<0.05; LV-siRNA2: 0.42±0.02, 0.76±0.04, 1.03±0.02, P<0.01) was significantly lower than HepG2 cells (0.59±0.02, 0.98±0.02, 1.63±0.02) in the control group. The proliferative capacity of HuH-7-80 cells with low expression in the EPIC1 group at 24, 48, 72 h (LV-siRNA1: 0.59±0.01, 0.73±0.02 and 1.31±0.05, P<0.05; LV-siRNA2: 0.43±0.04, 0.74±0.04 and 1.26±0.04, P<0.01) was significantly lower than that of the HuH-7-80 cells (0.64±0.02, 0.82±0.02 and 1.78±0.02) in the control group. The number of cells across the basement membrane in the EPIC1 group with low expression in HepG2 and HuH-7-80 cells (43.35±6.16, 55.40±8.18) was significantly less than that in the control group (80.67±5.14 and 74.73±6.13) (P<0.05). The apoptosis rate of HepG2 and HuH-7-80 cells with low expression in EPIC1 group was significantly higher than that in the control group [(2.60±0.96)% and (3.60±0.33)%], and the difference was statistically significant (P<0.01). Conclusion lncRNA EPIC1 is highly expressed in HCC tissues and cells. EPIC1 with low expression can reduce the capacity of proliferation and invasion of hepatoma cells and promote the apoptosis of hepatoma cells. Key words: Carcinoma, hepatocellular; Long non-coding RNA EPIC1; Proliferation; Invasion; Apoptosis