Rapid decay of engulfed extracellular miRNA by XRN1 exonuclease promotes transient epithelial-mesenchymal transition

Abstract

Extracellular vesicles (EVs) have been shown to play an important role in intercellular communication as carriers of DNA, RNA and proteins. While the intercellular transfer of miRNA through EVs has been extensively studied, the stability of extracellular miRNA (ex-miRNA) once engulfed by a recipient cell remains to be determined. Here, we identify the ex-miRNA-directed phenotype to be transient due to the rapid decay of ex-miRNA. We demonstrate that the ex-miR-223-3p transferred from polymorphonuclear leukocytes to cancer cells were functional, as demonstrated by the decreased expression of its target FOXO1 and the occurrence of epithelial-mesenchymal transition reprogramming. We showed that the engulfed ex-miRNA, unlike endogenous miRNA, was unstable, enabling dynamic regulation and a return to a non-invasive phenotype within 8 h. This transient phenotype could be modulated by targeting XRN1/PACMAN exonuclease. Indeed, its silencing was associated with slower decay of ex-miR-223-3p and subsequently prolonged the invasive properties. In conclusion, we showed that the ‘steady step’ level of engulfed miRNA and its subsequent activity was dependent on the presence of a donor cell in the surroundings to constantly fuel the recipient cell with ex-miRNAs and of XRN1 exonuclease, which is involved in the decay of these imported miRNA.

5΄-Vinylphosphonate improves tissue accumulation and efficacy of conjugated siRNAs in vivo

“…Furthermore, XRN1 and XRN2 play a role in miRNA stability (34–36), especially if miRNA is taken up from the extracellular space (37). XRN1 also regulates accumulation of viral dsRNA (38).…”

Deciphering the roles of FOXO1 in human neoplasms

“…Previous studies have demonstrated that low levels or activity of FOXO1 have a close relationship with tumorigenesis . FOXO1 silencing is related to suppressed EMT in A549 lung adenocarcinoma epithelial cells, which is evidenced by decreased epithelial markers (E‐cadherin) and enhanced mesenchymal markers (SNAIL, SLUG) . Helicobacter pylori infection is the major risk factor for gastric cancer.…”

“…34,35 FOXO1 silencing is related to suppressed EMT in A549 lung adenocarcinoma epithelial cells, which is evidenced by decreased epithelial markers (E-cadherin) and enhanced mesenchymal markers (SNAIL, SLUG). 36 Helicobacter pylori infection is the major risk factor for gastric cancer. In human gastric cancer epithelial cells, phosphorylated FOXO1 (pFOXO1), the inactive form of FOXO1, is highly expressed in the cytoplasm rather than the nucleus, revealing that the disruption of FOXO1 subcellular location might induce early gastric carcinogenesis among Helicobacter pylori-infected patients.…”

Structure‐guided design of immunomodulatory RNAs specifically targeting the cytoplasmic viral RNA sensor RIG‐I

“…Although they are 24-25 nucleotides approximately the length of miRNAs or siRNAs, immRNAs form stable hairpins with stable blunt duplex ends [6]. So they may not be easily degraded by 5 0 exonuclease Xrn1 and 3 0 exonuclease exosome complex [46,47]. They are also not like the long double-stranded RNA which could be cleaved by Dicer into 21-23mer siRNA.…”