Aim: To explore the inhibitory effect of sulfated polysaccharide from Masson pine (Pinus massoniana) pollen (SPPM60) on G2/M phase of human liver cancer HepG2 cells and its mechanism.
Methods: The proliferation rate of HepG2 cells was evaluated by methyl thiazolyl tetrazolium (MTT) colorimetric assay. The cycles of HepG2 cells were measured by flow cytometry when 200μg/ml concentration of SPPM60 was adopted, the expression of the genes related to cell cycle was detected by real-time PCR.
Results: SPPM60 inhibited the proliferation of HepG2 cells and the inhibition rate was elevated with increase of SPPM60 concentration. After treatment with 200μg/ml of SPPM60, the percentage of S phase cells was decreased, but that of G2/M phase was significantly increased (72h vs control: 32.96±0.33% vs 18.59±0.04%, 3.44±0.05% vs 18.30±0.08%, P<0.01). The results of real-time PCR showed that SPPM60 could down-regulate the mRNA levels of CDK1 and CyclinB (P<0.01), and up-regulate the expression of p53 and p21 (P<0.05).
Conclusion: SPPM60 causes arrest of HepG2 cells at G2/M phase, and the mechanism is related to the down-regulation of CDK1 and CyclinB and up-regulation of p53 and p21 expression.
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