Molecular chaperones in the acquisition of cancer cell chemoresistance with mutated TP53 and MDM2 up-regulation.

Utilizing the TCGA PANCAN12 dataset we discovered that cancer patients with mutations in TP53 tumor suppressor and overexpression of MDM2 oncogene exhibited decreased survival post treatment. Interestingly, in the case of breast cancer patients, this phenomenon correlated with high expression level of several molecular chaperones belonging to the HSPA, DNAJB and HSPC families. To verify the hypothesis that such a genetic background may promote chaperone-mediated chemoresistance, we employed breast and lung cancer cell lines that constitutively overexpressed heat shock proteins and have shown that HSPA1A/HSP70 and DNAJB1/ HSP40 facilitated the binding of mutated p53 to the TAp73a protein. This chaperone-mediated mutated p53-TAp73a complex induced chemoresistance to DNA damaging reagents, like Cisplatin, Doxorubicin, Etoposide or Camptothecin. Importantly, when the MDM2 oncogene was overexpressed, heat shock proteins were displaced and a stable multiprotein complex comprising of mutated p53-TAp73a-MDM2 was formed, additionally amplifying cancer cells chemoresistance. Our findings demonstrate that molecular chaperones aid cancer cells in surviving the cytotoxic effect of chemotherapeutics and may have therapeutic implications.