Figure 4. LncRNA Sox2OT-V7 silencing increases the sensitivity of OS cells to Dox. (A) Parantal U2OS cells and Dox-resistant U2OS/Dox cells were treated with a series of concentrations of Dox (0.001, 0,01, 0.1, 1, 10, and 100 μM) and examined for cell viability by MTT assay. (B) The expression of lncRNA Sox2OT-V7 in original U2OS and Dox-resistant U2OS/Dox cells was determined using real-time PCR. (C) U2OS/Dox cells were transfected with Lsh-NC or Lsh-Sox2OT-V7, treated with a series of concentrations of Dox (0.001, 0,01, 0.1, 1, 10, and 100 μM), and examined for cell viability by MTT assay. (D) Parental U2OS and Dox-resistant U2OS/Dox cells were treated with a series of concentrations of Dox (0, 1, and 2.5 μM) and cell apoptosis was examined by flow cytometry. **P<0.01, compared to the U2OS group; #P<0.05, ##P<0.01, compared to the 0 μM Dox group. (E) U2OS/Dox cells were transfected with Lsh-NC or Lsh-Sox2OT-V7, treated with 2.5 μM Dox, and examined for cell apoptosis by flow cytometry. **P<0.01, compared to U2OS or Lsh-NC group; ##P<0.01, compared to 0 μM Dox group.