Establishment of paclitaxel-resistant breast cancer cell lines

The human TNBC cell lines (MDA-MB-453 and MCF7) were purchased from BeNa Culture Collection (Beijing, China), All cells were regularly authenticated using short tandem repeat (STR) DNA profiling and tested to confirm that they were mycoplasma contamination-free. The above cells were maintained in the DMEM medium (Gibco, USA) containing 10% fetal bovine serum (FBS, Gibco) under the conditions with 5% CO₂ atmosphere at 37°C. In addition, according to the experimental protocols recorded in our previous work (42 (link)), the paclitaxel-resistant MDA-MB-453/PTX and MCF7/PTX cell lines was established by treating the parental paclitaxel-sensitive BC cells with continuous paclitaxel treatment in a step-wise manner. The PR-BC cells were maintained in the DMEM medium (Gibco, USA) containing 10% fetal bovine serum, and the PR-BC cells at passage 2 to 4 with paclitaxel-resistant properties were used in this study. Moreover, the vectors for gp96 overexpression/downregulation and p53 overexpression were synthesized by Sangon Biotech (Shanghai, China), which were delivered into the TNBC cells by using the Lipofectamine 2000 transfection reagent (Invitrogen, USA). Moreover, the PS-BC cells were exposed to the hypoxic environment (0.2% oxygen, 5% CO₂, and 37°C) for three days to establish the hypoxic PS-BC cell models as previously described (43 (link)).