Figure 3.

Synergistic effect of OCT and DDP on 8305C-SP cell proliferation inhibition. (A) 8305C-SP cell proliferation rates at different concentrations of OCT. (B) 8305C-SP cell proliferation rates at different concentrations of DDP. (C) 8305C-SP cell proliferation rates at 10 µM OCT in combination with different concentrations of DDP. (D) 8305C-SP cell proliferation rates at 5 µM DDP in combination with different concentrations of OCT. (E) Isobologram analysis of the combination effect of OCT and DDP. First, it was assumed that the individual IC₅₀ values of OCT and DDP were a (0, 173.8) and b (47.83, 0) in the coordinate axis, which were able to align into a straight line as ab. Next, two new IC₅₀ values, c (5, 54.58) and d (10.44, 10), were obtained following combination treatment and cd was aligned into a new straight line. If cd coincides with ab, then these two drugs do not interfere with each other. If cd is located above ab, these two drugs are antergic. If cd is located below ab, these two drugs are synergetic. OCT and DDP interaction belonged to the third type, so their combined effect is synergy. (F) The volume of mice tumor was determined with the treatment of OCT and/or DDP. (G) The weight of each tumor mass after 25 days. *P<0.05 (one-way analysis of variance). OCT, octreotide; DDP, cisplatin; SP, side population; IC₅₀, half-maximal inhibitory concentration.