Figure 2.

Apoptosis induction by DNA methyltransferase inhibitor. To clarify the induction of apoptosis during the growth suppression of OCUM‐2M and MKN‐74 cell lines by combined exposure of 5‐aza‐CdR with anticancer drugs, cells were double stained with Annexin V–FITC and PI. Cells staining annexin V positive and PI negative were considered to be apoptotic. Anticancer drugs were added to the cancer cell cultures at the IC₅₀ for each cell line. In OCUM‐2M, 5‐aza‐CdR induced apoptosis at a rate of 4.7%, compared with the control of 2.4%. The apoptosis rates induced by SN38, and GEM alone were 8.8%, and 12.7%, respectively. In addition, the apoptosis rates induced by combined exposure of 5‐aza‐CdR with anticancer drugs, SN38, and GEM were 21.4%, and 24.5%, respectively. In MKN‐74, 5‐aza‐CdR induced apoptosis at a rate of 3.7%, compared with the control rate of 5.7%. The apoptosis rates induced by SN38, GEM, PTX and OXA alone were 15.8%, 14.4%, 16.7% and 23.4%, respectively. The apoptosis rates induced by combined exposure of 5‐aza‐CdR with SN38, GEM, PTX and OXA were 26.5%, 21.7%, 38.9% and 38.4%, respectively. 5‐Aza‐CdR at 5 µM increased apoptosis induced by SN38 and GEM in both cell lines, and increased the apoptosis rate induced by PTX and OXA in MKN‐74 cells.