Figure 2.

Resistant MCF7 cells responded differently to the different NAC treatmenst and up‐regulated HER2 and EGFR signalling and changed their subtype from luminal A to luminal B HER2 type. (a) Representative western blots illustrating the comparison between protein levels in control and resistant MCF7 variants. The MCF7 cells resistant to 4xAC showed significantly increased NRP‐1, TNFR2, PI3K‐p110α, PTEN (trend of increase), p‐AKT‐S473, FAK, and its phosphorylated form (p‐FAK and p‐NF‐κB_p65) and HDAC3 but down‐regulated integrin β3 significantly. Unlike cells resistant to 4xAC, those resistant to 4xAC + 4xPAC showed a significant down‐regulation in NRP‐1 and an up‐regulation in BCRP levels. On the other hand, resistance to 4xAC + 4xPAC down‐regulated PI3K‐p110α and the phosphorylated forms of Akt‐S473, FAK, and NF‐κB_p65. Additionally, cells resistant to 4xAC + 4xPAC overexpressed TNFR2, integrin β3, cyclin B1, and HDAC4. DNMT1 was down‐regulated in the cells resistant to 4xAC and to a higher extent in cells resistant to 4xAC + 4xPAC. (b) Although HER2 and EGFR were not detected in the control cells, their levels and the corresponding phosphorylated forms were induced in the resistant variant cells. ER‐α was also overexpressed in resistant cells. Individual protein band density quantification was normalized against their corresponding GAPDH bands. Data are presented as the mean relative density (arbitrary units, a.u.) ± SD (n = 5). *P < .05, significantly different from control cells; ANOVA and Tukey's post hoc test