Effect of MTDH gene overexpression on clinical sensitivity of doxorubicin.

<p>(A) MTDH mRNA expression determined by real time-PCR after MTDH plasmid was transfected for 48 h in MDA-MB-231 cells (untransfected group 1.00±0.00, blank plasmid group 1.03±0.12 and MTDH transfected group 3.25±0.02). (B) MTDH protein expression determined by western blot after MTDH plasmid was transfected for 48 h in MDA-MB-231 cells (untransfected group 0.48±0.07, blank plasmid group 0.50±0.06 and MTDH transfected group 1.27±0.08). (C) The cell growth curves showed the MDA-MB-231 cell growth was promoted after MTDH gene was transfected into cells. (D) The inhibitory rates measured by a MTT assay of MDA-MB-231 cells subjected to 1 mg/L doxorubicin treatment for 24 h were (60.72 ± 0.01)% and (41.68 ± 0.03)% before and after transfection of MTDH plasmid (<i>P</i> = 0.000). (D, E) The apoptosis rates of MDA-MB-231 cells measured by FCM subjected to 1 mg/L doxorubicin treatment for 24 h were (39.76 ± 0.44)% and (20.59 ± 0.59)% before and after transfection of MTDH plasmid (<i>P</i> = 0.000). <b>(</b>F, G) In the MTDH transfected group, the cell cycle measured by FCM and showed a increase in the proportion of cells in the S and G2/M phase and decrease in cells in the G0/G1 phases compared to the untransfected group. When treated with doxorubicin, the cell cycle arrest more at G0/G1 phase and reduction of G2/M phase in MTDH untransfected group compared to the transfected group. Values are expressed as means ± SD of at least three independent experiments, *p<0.05, **p<0.01 and ***p<0.001 as compared with their respective untransfected group.