Fig. 2.

The cell kinetic effect of P-ASA on SW480 colon cancer cells. SW480 cells were grown overnight and treated with P-ASA (MDC-43) as shown. (A) Cell proliferation assay based on bromodeoxyuridine (BrdU) incorporation into DNA during the S-phase of the cell cycle. The percentage of bromodeoxyuridine positive cells is shown in the right upper corner of each panel. (B) Cell cycle analysis by PI staining for DNA content of cells treated with and without P-ASA. Results, quantified in (C), demonstrate the induction of a G₂/M to G₀/G₁ block by P-ASA. (D) Flow cytometric analysis of cells stained with PI and Annexin V (A). A(−)/PI(−) cells are viable cells; A(+)/PI(−) are early apoptotic; A(+)/PI(+) are late apoptotic and A(−)/PI(+) are necrotic. The numbers inside each panel represent the percentage of cells in each category. NAC 20 mM was used to pretreat the cells for 4 h. (E) The effect of pretreatment with NAC on cell viability in response to P-ASA was determined by trypan blue staining and cell counting. Figures are representative of two experiments, whose results were within 10%.