Figure 5.

Low doses of perifosine enhance the cytotoxic drug activities in MYCN-amplified BE(2)-C cells. (A) Total dead cell number performed using Trypan Blue dye exclusion assay on a panel of three MYCN-amplification neuroblastoma cell lines treated for 72 h of the IC₁₀ perifosine concentration alone, IC₂₀ vincristine alone, or their combination. Data are reported as averages (n = 3, ± SEM). Statistics were calculated by comparing the cytotoxic agent-treated cells with the combination-treated cells (*, p < 0.05; **, p < 0.01). (B) Clonogenic assays were done on BE(2)-C cells treated with a range of vincristine alone (black line) or combined with IC10 perifosine (blue line). Data are reported as averages (n = 3, ± SEM). Extra sum of F² test was used to determine statistical significance between nonlinear regression of vincristine alone versus combination treatment. (C) Western blot analysis in protein extracts from BE(2)-C cells after 48 h of treatment of IC₁₀ or IC₅₀ of perifosine alone (PF), IC₂₀ or IC₅₀ of cytotoxic drug alone (VCR: vincristine, VP16: etoposide and Doxo: doxorubicin), or their combination (C: combination of IC₁₀ perifosine with IC₂₀ cytotoxic drug). Blots were probed with the indicated antibodies. GAPDH was used as a loading control.