pPep from Schroet induces cell cycle arrest and inhibits the migration of MC-4 gastric tumor cells.

The aim of the present study was to investigate the effect of purified protein (pPep) extracted by polyvinylpyrrolidone from the fungus Schroet on the proliferation and cell cycle progression of MC-4 human gastric tumor cells. Using polyvinylpyrrolidone, pPep was extracted from . MC-4 cells were cultured with 30, 60 or 90 µg/ml pPep, with 5-fluorouracil used as a positive control. Survival rates of treated cells were significantly decreased compared with those of the untreated control group in a dose-dependent manner. Using flow cytometric analysis, cells treated with pPep were demonstrated to arrest in S phase and exhibit abnormal G0/G1 and G2/M phase cell cycle distribution. In addition, a wound healing assay demonstrated that pPep significantly inhibited the migration of MC-4 cells. The mRNA and protein expression levels of cyclin D1/cyclin-dependent kinase (CDK) 4, cyclin B/CDK1, cyclin A/CDK2, matrix metalloproteinase (MMP)-2 and MMP-9 were determined using reverse transcription-quantitative polymerase chain reaction analysis and western blotting. The mRNA expression level of CDK4 and cyclin A was significantly increased compared with the untreated control; however, cyclin D1, CDK1, CDK2, cyclin B, MMP-2, and MMP-9 exhibited a significantly decreased mRNA expression level, indicating that there is a negative association between concentration and cyclin D1 expression levels. The expression of the cycle arrest-associated proteins and migration-associated proteins examined were similar to the observed mRNA expression levels. In conclusion, pPep was identified to inhibit migration of and cause S phase cell cycle arrest in MC-4 cells.