Oncogenic mutant p53 proteins are selectively shuttled by cancer extracellular vesicles to educate the tumor microenvironment

Introduction

Gain-of-function mutation in p53 imparts an aggressive traits to the cells when compared to the cancer cells harboring inactivating mutations or wild-type p53. Notably, multiple studies have delineated the presence of GOF-mutant p53 protein in untransformed cells or in stromal compartments of tumor microenvironment (TME). In recent years, the involvement of extracellular vesicles (EVs) in cell-to-cell communication has emerged as major route by which cancer cells can interact and educate TME. To this end, we hypothesize that mutant p53 protein can be shuttled via EVs to TME cells thus shedding light on a novel non-cell autonomous role of mutant p53 cancers

Methods

EVs were isolated from various cancer cell lines differing by their p53 status and the effect on neighboring cancer cells and TME cells was studied in vitro and in-vivo. We also utilized the human colorectal Colo-320DM cancer cell xenograft model and. FFPE sections of subcutaneous tumors derived from the Colo-320DM xenografts that were stained for p53 using antibody that specifically recognizes human p53.

Results

Our data demonstrated that mutant p53 protein can be selectively sorted into EVs; that mutant p53 in EVs can be taken up by neighboring cancer cells and macrophages. Evident of macrophage education was seen with the increased expression and secretion of pro-inflammatory cytokines. Notably, mutant p53 expression was also found in non-tumor cells in both human cancers, and in non-human tissues in human xenografts.

Summary

Cancer cells harboring GOF p53 mutants can package mutant p53 proteins in EVs, and deliver them to TME.