Pro-Inflammatory Microenvironment Modulates the Transfer of Mutated TP53 Mediated by Tumor Exosomes

Abstract

Exosomes released from tumor cells are instrumental in shaping the local tumor microenvironment to allow cancer progression. Recently, it has been shown that tumor exosomes carry large fragments of dsDNA, which may reflect the mutational status of parental cells. Although it has been described that a stressful microenvironment can influence exosomal cargo, the effects on DNA packing and its transfer into recipient cells have yet to be investigated. Here, we report that exosomes derived from SW480 (human colorectal adenocarcinoma cell line) cells can carry dsDNA fragments containing the entire coding sequence of both TP53 and KRAS genes, harboring the SW480-related TP53 c.818G > A and KRAS c.35G > T typical mutations. We also report the following: that cell stimulation with lipopolysaccharides (LPS) promotes the selective packaging of the TP53 gene, but not the KRAS gene; that exosomes secreted by SW480 cells efficiently transfer the mutated sequences into normal CCD841-CoN colon epithelial and THLE-2 hepatic cells; that this mechanism is more efficient when the cells had been previously incubated with pro-inflammatory cytokines; that the TP53 gene appears actively transcribed in both recipient cells; and that mutated mRNA levels are not influenced by cytokine treatment. Our data strongly suggest that pro-inflammatory stimulation promotes the horizontal transfer of an oncogene by exosomes, although this remains a rare event. Further studies are needed to assess the impact of the oncogenic transfer by exosomes in malignant transformation and its role in tumor progression.

Roles of Exosome Genomic DNA in Colorectal Cancer

“…The author also proved that LPS activated TLR4 of colon cancer cell SW480 and promoted the packaging of mutant TP53 in exosomes but could not promote the selective packaging of the KRAS gene. It indicates that the mechanism of gDNA packaging to exosomes is not random ( Domenis et al, 2021 ). More and more experiments proved that exosomes derived from primary tumors could be loaded with specific molecules ( Stobiecka et al, 2019 ; Baris et al, 2021 ), and the expression or lack of these molecules is helpful to the phenotype transformation of recipient cells.…”

Exosomes in Genitourinary Cancers: Emerging Mediators of Drug Resistance and Promising Biomarkers

“…For example, Domenis et al reported that exosomes derived from SW480 (human colorectal adenocarcinoma cell line) cells contributed to transferring dsDNA fragments containing the entire coding sequence of both tumor protein p53 ( TP53 ) and KRAS proto-oncogene ( KRAS ) genes, harboring the TP53 c.818G > A and KRAS c.35G > T typical mutations. In addition, the stimulation of lipopolysaccharides (LPS) could promote the packaging of the TP53 gene rather than KRAS gene indicating the selective package of gDNA 26 . Furthermore, recent studies have also suggested the essential role of exosomal DNA in the development of drug resistance in malignant cells.…”

Small extracellular vesicle DNA-mediated horizontal gene transfer as a driving force for tumor evolution: Facts and riddles

“…However, it is particularly important that this system can adapt quickly to stress (e.g., genotoxic oncotherapies) by increasing micronucleus formation and the concomitant packaging of gDNA into sEVs (sEV-gDNA) ( Figure 1D ) ( 24 ). The dynamic adaptation of sEV-mediated DNA release is further supported by the changing quality and/or quantity of transported genetic content (e.g., the proportion of genomic and mitochondrial (mt) DNA, as well as the average size of DNA fragments) upon diverse environmental effects ( 29 , 30 ).…”

“…It may lead to an increased gDNA content in MVB-originated sEVs (i.e., exosomes) ( 24 , 27 ). The rapid change in gDNA content of exosomes by existing stress factors (e.g., effects of artificial selection or the pro-inflammatory microenvironment) have been observed ( 24 , 29 , 30 ), however, it is not known how similar stress conditions may regulate the non-MVB-originated sEV release. Presumably, these sEV release pathways may change dynamically upon exposure to various microenvironmental or therapy-induced stress factors.…”

“…The presence of clonal heterogeneity in cancer ( 81 ) suggests that the HGT-based cooperation among the admixed- or the spatially non-uniformly distributed subclones may be a rare event. Regarding its frequency, it must be emphasized that some phenomena associated with oncogenic HGT can be highly context-dependent ( 23 , 24 , 29 , 30 ). Thus, the successful incorporation rate of sEV-mediated HGT may differ greatly depending on the imposed selection pressure.…”