Résumé
To investigate the radiosensitizing effects of Radix Angelicae Sinensis-Radix Hedysari [HAS-RH [an ultra- filtration extract]] and its underlying mechanisms in human liver cancer cells H22. This study was conducted between September 2010 and August 2012 in the Gansu University of Traditional Chinese Medicine, Lanzhou, China. The groups were assigned as the control group, drug [RAS-RH] group, [12]C[6-] radiation group, and combination group. The cell counting kit-8 assay, colony formation assay, cell cycle changes, and apoptosis analysis were carried out, and survivin and casepase-9 were evaluated by reverse transcription polymerase chain reaction and Western blot analyses in the 4 groups. The inhibitory effect of RAS-RH on H22 cells was dependent on both concentration and time, RAS-RH was able to enhance the radiosensitivity of H22 cells by increasing cell survival fraction and radiosensitization parameters. Apoptosis and the gap2/mitosis [G2/M] phase transition induced by [12]C[6-] heavy ion radiation was enhanced by RAS-RH treatment. Irradiation, combined with RAS-RH, decreased survivin expression while increasing casepase-9 expression in H22 cells. The RAS-RH increased the radiosensitivity of H22 cells of [12]C[6+] heavy ion radiation significantly, and its possible mechanism of radiosensitization is to enhance caspase-dependent apoptosis through the down-regulation of survivin, thus, it can be used as an effective radiosensitizer
Résumé
<p><b>OBJECTIVE</b>To 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.</p><p><b>METHODS</b>The 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.</p><p><b>RESULTS</b>The 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).</p><p><b>CONCLUSION</b>UEMHP 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.</p>