Reversion of malignant phenotype of human hepatocellular carcinoma cells by saikosaponin D in vitro

The present study aimed to investigate the effect of Saikosaponin D (SSD) on the malignant phenotype of HepG2 cells and its potential mechanism in order to provide evidence for prevention and treatment of hepatocellular carcinoma (HCC) with SSD. HepG2 cells in the logarithmic phase were randomly divided into two groups: SSD group and control group. Cells in the SSD group were treated with 10 mg/L SSD for 48 h and those in the control group were untreated. Cell inhibition rate was measured by methlthiazolyl tetrazolium (MTT) assay, cell morphology detected by Giemsa staining followed by observation under a contrast phase microscope, the contents of alpha-fetoprotein (AFP) and albumin (ALB) in the supernatant measured by chemiluminescence and radioimmunoassay, respectively. Cell migration was determined by transwel chamber assay and flow cytometry done to measure the cell cycle. Reverse transcriptase- Polymerase chain reaction (RT-PCR) and immunohistochemistry were performed to measure the messenger ribonucleic acid (mRNA) and protein expression of p27, respectively. The growth of HepG2 cells was significantly inhibited after SSD treatment for 48 h (P<0.05). Cells in the SSD group had normal differentiation, became small and round and had small, round nucleus and reduced nuclear-cytoplasmic ratio. When compared with control group, the ALB level was significantly increased (P<0.05) and AFP level markedly reduced (P<0.05). In addition, the number of migrating cells in the SSD group was lower than that in the control group (P<0.01). The SSD treated cells had dramatically higher proportion of cells in G1 phase (P<0.05) and markedly lower proportion of cells in S phase (P<0.05). Furthermore, the mRNA and protein expressions of p27 in the SSD treated HepG2 cells were higher than in those without SSD treatment. SSD can reverse the malignant phenotype of HepG2 cells, which may be associated with up-regulation of p27 expression, arrest of cell cycle in G1 phase and promoted differentiation of HepG2 cells.   Key words: Saikosaponins D, HepG2, malignant phenotype, p27.