Cytoplasmic p21 is responsible for paclitaxel resistance in ovarian cancer A2780 cells

Purpose: P21 which bound to cyclin-dependent kinase complexes was originally described as a suppressor of cancer cell proliferation, while many recent studies have shown p21, when accumulated in the cell cytoplasm, could promote tumor progression. This study was conducted to investigate the role of p21 in the paclitaxel (PTX) resistance of ovarian cancer. Materials and Methods: Regulation of cytoplasmic p21 was performed through transfection of Akt2 constitutively active vector, Akt2 shRNA and p21 siRNA in the ovarian cancer cell line A2780. Akt2, p-Akt, and p21 expression were examined by Western blot and cell apoptosis rates were assessed by flow cytometry after treatment with PTX. Results: Induction of p21 translocation into the cytoplasm via constitutively active Akt2 transfection in A2780 enhanced the resistance to PTX, while inhibition of p21 translocation into the cytoplasm via Akt2 shRNA transfection in A2780 cells significantly increased PTX treatment sensitivity. Furthermore, knockdown of cytoplasmic p21 by direct p21 siRNA transfection in Akt2 overexpressed A2780 cells notably increased PTX-induced apoptosis. Conclusion: Cytoplasmic p21 may represent a potential therapeutic target for ovarian tumors that are resistant to PTX treatment.