Doxorubicin induces Aberrant Self-Assembly of P53 by Phase Separation

The role of genetic mutations on the destabilization and aggregation of p53 has been extensively studied. The prevalence of WTp53 aggregates in the cancer cell lines and tumour biopsy samples of cancer patients raises the possibility of external factors that could lead to aggregation of p53. Existing reports suggest that the cellular level of p53 is increased after administration of doxorubicin, a commonly used chemo-drug for cancer treatment. However, there is no evidence which could establish a direct link between chemotherapeutic drugs and p53 aggregation. in this study, we have used a complementary imaging and spectroscopic techniques to understand the effect of doxorubicin on the self-assembly of the WTp53 and its R273 variants. The present work shows that doxorubicin interacts with the WTp53 and its mutant variants and trigger their anomalous self-assembly. The fluorescence microscopy further reveals the co-assembly of doxorubicin and p53 into droplets. interestingly, doxorubicin-induced liquid-liquid phase separation of WTp53 whereas mutant variants [R273C]p53 and [R273L]p53 phase separate out without any external aid in the crowded environment indicating their destabilizing effect. The [R273C]p53 undergoes liquid-liquid phase separation whereas [R273L]p53 experiences liquid-solid transition. The phase separation of p53 and doxorubicin further leads to the aggregation of p53. Thus, our study points out that chemotherapeutic drugs like doxorubicin induce phase separation mediated p53 aggregation which may be a cause for cancer relapse.