Figure 7. Combination treatment of NPRL2 and cisplatin induces strong cell arrest in G2/M phase.

The cell cycle in tumor cells treated with NPRL2 and IC₂₀ value of cisplatin was analyzed by flow cytometry with use of the APO-BRDU KIT. (A) The shift in cell cycle parameters of cells treated with NPRL2 is manifested as clear G1 and G2 peaks 72 h after treatment. In contrast, the cell cycle distribution showed an increase in the G2/M population after treatment with empty vector and cisplatin compared with cells treated with NPRL2 alone. The shift in cell cycle distribution was seen in cells treated with NPRL2+ cisplatin: the G2/M phase population strongly increased, whereas the G1 phase population decreased. (B) The cell cycle shift was analyzed at 24, 48, and 72 h after treatment. The combination of NPRL2 and cisplatin significantly increased the G2/M population in a time-dependent manner (P<0.001 at 48 h; P<0.0001 at 72 h) and increased the sub-G0-G1 population (P<0.001 at 72 h), compared with all other treatments. Bars, SDs of the mean from three individual experiments.