Cytoplasmic translocation of p21 mediates NUPR1-induced chemoresistance: NUPR1 and p21 in chemoresistance.

The expression of Nuclear Protein 1 (NUPR1) is associated with chemoresistance in multiple malignancies. We previously reported that NUPR1 functions as a transcriptional cofactor for the p300-p53 complex and transcriptionally regulates p21 expression. In the present study we investigated the activity of NUPR1 in p53-deficient, triple-negative, inflammatory SUM159 breast cancer cells. Our studies reveal that NUPR1 confers growth benefit and chemoresistance by causing Akt-mediated phosphorylation and subsequent cytoplasmic re-localization of p21 and activation of the anti-apoptotic Bcl-xL protein. Our findings elucidate a NUPR1-PI-3-K/Akt-phospho-p21 axis that functions in p53-negative, inflammatory breast cancer cells to enhance chemoresistance in breast cancer.