Oncogenic Gain of Function in Glioblastoma Is Linked to Mutant p53 Amyloid Oligomers

Murilo M Pedrote,Jerson L Silva,Tania C.L.S Spohr,Guilherme A.P De Oliveira,Michelle F Motta,Giulia D.S Ferretti,Douglas R Norberto,Flavia R.S Lima,Enrico Gratton

doi:10.1016/j.isci.2020.100820

Abstract

SummaryTumor-associated p53 mutations endow cells with malignant phenotypes, including chemoresistance. Amyloid-like oligomers of mutant p53 transform this tumor suppressor into an oncogene. However, the composition and distribution of mutant p53 oligomers are unknown and the mechanism involved in the conversion is sparse. Here, we report accumulation of a p53 mutant within amyloid-like p53 oligomers in glioblastoma-derived cells presenting a chemoresistant gain-of-function phenotype. Statistical analysis from fluorescence fluctuation spectroscopy, pressure-induced measurements, and thioflavin T kinetics demonstrates the distribution of oligomers larger than the active tetrameric form of p53 in the nuclei of living cells and the destabilization of native-drifted p53 species that become amyloid. Collectively, these results provide insights into the role of amyloid-like mutant p53 oligomers in the chemoresistance phenotype of malignant and invasive brain tumors and shed light on therapeutic options to avert cancer.

Highlights

The p53 tumor suppressor is a key protein involved in the cellular network of different types of cellular stress (Vousden and Lane, 2007) and the most frequently mutated gene in human cancer (Bisio et al, 2014; Muller and Vousden, 2013)
Amyloid Oligomers of a Chemoresistance p53 Mutant Accumulate in Glioblastoma Brain Cell Tumors Chemoresistance related to aberrant p53 involves the regulation of several target genes
We confirmed the increased RNA levels of MGMT and phosphatase and tensin (PTEN) (Figures S1A–S1C) and the increased cell motility upon scratch formation (Figures S1D and S1E) in T98G glioblastoma cells expressing a p53 protein with Met-to-Ile substitution at position 237 of p53 compared with wt-p53-expressing U87 glioblastoma cells

Summary

Introduction

The p53 tumor suppressor is a key protein involved in the cellular network of different types of cellular stress (Vousden and Lane, 2007) and the most frequently mutated gene in human cancer (Bisio et al, 2014; Muller and Vousden, 2013). A hotspot mutant of p53C (R248Q) was shown to seed the aggregation of the wild-type (wt) form of p53 in vitro, a typical behavior of a prion-like protein (Ano Bom et al, 2012; Silva et al, 2014a). Previous studies have revealed the occurrence of cell-to-cell transmissibility events involving p53 (Forget et al, 2013; Lee et al, 2009, 2013), which supports the suggested prion-like nature of this tumor suppressor. In vitro studies using the fluorescence of p53C have shown the presence of wt-p53C molten globule states prone to amyloid aggregation (Pedrote et al, 2018). Different aggregation phenotypes were observed in biopsies of breast tumor (Levy et al, 2011) and cell lines of different cancers, including breast (Ano Bom et al, 2012), ovarian (Yang-Hartwich et al, 2015), and prostate cancers (Kluth et al, 2014), supporting the hypothesis that p53 undergoes misfolding prior to amyloid aggregation in these cells

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