OBJECTIVETo investigate the effects of the ultra-filtration extract mixture from Hedysarum Polybotrys (UEMHP) on the radiosensitivity of HepG2 cells, and to explore its possible mechanisms.

METHODSThe proliferation inhibition effects of UEMHP on HepG2 cells was detected by CCK-8 assay. The colony formation assay was used for the survival fraction (SF) analysis. The distribution of the cell cycle and the apoptosis rate were detected using flow cytometry (FCM). The survivin mRNA expression level was detected using reverse transcription-PCR assay.

RESULTSThe inhibition of UEMHP on HepG2 cells was time-and dose-dependent at the concentration ranging between 5 -50 mg/L (P < 0.05). The parameters of the two curve for SF (P < 0.05) showed statistical difference between the irradiation group and the UEMHP irradiation group. UEMHP could inhibit the clone formation of HepG2 cells and enhance the radiosensitivity of HepG2 cells. The results of FCM showed that UEMHP could induce G2/M phase arrest. The apoptosis rate in the UEMHP irradiation group (21.42% +/- 3.74%) was higher than that in the control group (5.35% +/- 0.41%), the only UEMHP group (10.36% +/- 1.75%), or the irradiation group (10.58% +/- 2.01%) (P < 0.01). RT-PCR showed that the survivin mRNA expression level was lower in the UEMHP irradiation group (0.31 +/- 0.02) than in the control group (0.82 +/- 0.06) and the irradiation group (0.58 +/- 0.04) respectively, showing statistical difference (P < 0.01).

CONCLUSIONUEMHP can enhance the radiosensitivity of HepG2 cells, and its possible mechanisms might be correlated to down-regulating the survivin mRNA expression and promoting the apoptosis.