fig3

Figure 3. Epigenetic regulation mechanisms in cancer cells that result in acquired irinotecan resistance. Methylation in a promoter region of a drug efflux transporter, ABCG2, and stabilization of a mRNA binding protein, HuR, through miR-519c function are depicted as epigenetic regulation mechanisms. When positive regulation mechanisms are prevailing in cancer cells, ABCG2 gene expression will be enhanced. Thus, cancer cells will become resistant to irinotecan.