Figure 3. miR-644a overexpression acts as a therapy sensitizer in breast cancer cells and its expression correlates with doxorubicin resistance in vivo xenografts.

(A and B) Effect of miR-644a overexpression on the response of MDA-MB-231 (A) and MCF-7 (B) cells to doxorubicin. (C) qRT-PCR analysis of miR-644a expression in xenografts sensitive or resistant to doxorubicin. Nude mice were subcutaneously injected with MDA-MB-231 cells and treated with doxorubicin. Among the treated mice, sensitive and resistant tumors were selected based on changes in tumor volumes upon successive drug treatments. n = 4. (D–F) Effect of miR-644a overexpression on the response of MDA-MB-436 cells to cisplatin (D), response of MCF-7 cells to tamoxifen (E), and response of SKBR-3 cells to gefitinib (F). IC50 values for each condition are given on the left bottom corners of each curve with a color code.