Expression of lysine-specific demethylase 1 in hepatocellular carcinoma tissues and its effect on cell proliferation and invasion

Abstract

Objective To investigate the expression of lysine-specific demethylase 1 (LSD1) in hepatocellular carcinoma tissues, and to explore the effects of down-regulation of LSD1 gene expression on proliferation and invasion of human hepatoma HepG2 cells. Methods A total of 91 cases of hepatocellular carcinoma undergoing elective surgery in our hospital and Henan Cancer Hospital were selected. Immunohistochemistry was used to detect the expression of LSD1 protein in hepatocellular carcinoma tissues and adjacent tissues. Human hepatoma HepG2 cells were cultured and divided into LSD1 interference sequence group, negative control group and blank group. Real-time fluorescent quantitative polymerase chain reaction (FQ-PCR) was used to detect the expression of LSD1 gene in cells. Methyl thiazol tetrazolium (MTT) assay was used to detect cell proliferation. Transwell chamber was used to detect cell invasion. Western blotting was used to detect the expression of LSD1, Snail, E-cadherin and N-cadherin proteins in cells. Results The positive expression rate of LSD1 protein in hepatocellular carcinoma tissues was 81.32%, which was significantly higher than that in adjacent tissues (35.16%, P<0.01). The expression of LSD1 protein in hepatocellular carcinoma tissues was related to the degree of differentiation, TNM staging and vascular invasion (P<0.05). The relative expression level of LSD1 mRNA in LSD1 interference sequence group was 1.19±0.10, which was significantly lower than that in the negative control group and blank group (2.29±0.14 and 2.34±0.11, P<0.05). The absorbance (A) values at 24, 48, 72 and 96 h in the LSD1 interference sequence group were 0.23±0.05, 0.32±0.08, 0.38±0.08 and 0.52±0.03, respectively, which were significantly lower than those in the negative control group (0.38±0.08, 0.49±0.05, 0.67±0.04 and 0.77±0.10) and blank group (0.33±0.03, 0.52±0.09, 0.70±0.08 and 0.78±0.07, P<0.05). The number of invasive cells in the LSD1 interference sequence group was (86.3±3.9), which was significantly less than that in the negative control group (110.6±9.4) and the blank group (117.7±7.0, P<0.05). The relative expression levels of LSD1, Snail, and N-cadherin proteins in the LSD1 interference sequence group were (0.25±0.03, 0.30±0.02 and 0.32±0.03), which were significantly lower than those in the negative control group (0.77±0.06, 0.76±0.10 and 0.67±0.04) and blank group (0.84±0.14, 0.74±0.07 and 0.69±0.06, P<0.05), and the relative expression level of E-cadherin protein (0.71±0.05) was significantly higher than in the negative control group (0.37±0.02) and blank group (0.34±0.04, P<0.05). Conclusion LSD1 protein was highly expressed in hepatocellular carcinoma tissues, and might play an important role in the proliferation and invasion of human hepatoma HepG2 cells through epithelial-mesenchymal transition. Key words: Carcinoma, hepatocellular; Lysine-specific demethylase 1; Proliferation; Invasion; Epithelial-mesenchymal transition