ABSTRACT
OBJECTIVE To investigate whether α-lipoic acid(α-LA)can promote the anti-prolifera-tion effect of pyrrolidine dithiocarbamic acid(PDTC)in Hep-2 cells. METHODS The laryngeal carcino-ma Hep-2 cells were cultured with α-LA,PDTC or α-LA+PDTC respectively for 12,24 and 48 h. The proliferation of Hep-2 cells was detected by WST-1 assay and soft agar colony formation while apoptosis and cell cycle were analyzed by Hoechst33258 staining and flow cytometry. RESULTS α-LA 5 -500 μmol·L-1 could not inhibit Hep-2 cell proliferation,but PDTC 5 -50 μmol·L-1 could( P ﹤0.05,P ﹤0.01). The cell proliferation inhibitory rate of PDTC 5 μmol·L-1 combined with α-LA 5,10 and 20 μmol·L-1 groups was much higher than in control group(P﹤0.01)and PDTC alone group(P﹤0.05). When α-LA 5 μmol·L-1 was used in combination with PDTC 5 μmol·L-1 for 12-48 h,the cell proliferation was inhibited in a time-dependent manner(r=0.987,P﹤0.05). When the cells were treated for 24 h,the number of soft agar colony formations in combined group was significantly smaller than that of both α-LA alone group(P﹤0.01)and PDTC alone group(P﹤0.05). The result of Hoechst33258 staining and flow cytometry indicated that after combined treatment with PDTC 5 μmol·L-1 and α-LA 5 μmol·L-1 for 24 h,the level of apoptosis and the percentage of cells in G2 / M stage were significantly increased compared with PDTC alone or α-LA alone treatment. CONCLUSION α-LA can enhance the anti-proliferation and pro-apoptosis effect of PDTC in Hep-2 cells.