TP53 drives abscopal effect by secretion of senescence-associated molecular signals in non-small cell lung cancer

Anna Tesei, Chiara Arienti, Gianluca Bossi, Spartaco Santi, Ilaria De Santis, Alessandro Bevilacqua, Michele Zanoni, Sara Pignatta, Michela Cortesi, Alice Zamagni, Gianluca Storci, Massimiliano Bonafè, Anna Sarnelli, Antonino Romeo, Carola Cavallo, Armando Bartolazzi, Stefania Rossi, Antonella Soriani, Lidia Strigari

Research output: Contribution to journalArticlepeer-review


BACKGROUND: Recent developments in abscopal effect strongly support the use of radiotherapy for the treatment of metastatic disease. However, deeper understanding of the molecular mechanisms underlying the abscopal effect are required to best benefit a larger proportion of patients with metastasis. Several groups including ours, reported the involvement of wild-type (wt) p53 in radiation-induced abscopal effects, however very little is known on the role of wtp53 dependent molecular mechanisms.

METHODS: We investigated through in vivo and in vitro approaches how wtp53 orchestrates radiation-induced abscopal effects. Wtp53 bearing (A549) and p53-null (H1299) NSCLC lines were xenotransplanted in nude mice, and cultured in 2D monolayers and 3D tumor spheroids. Extracellular vesicles (EVs) were isolated from medium cell culture by ultracentrifugation protocol followed by Nanoparticle Tracking Analysis. Gene expression was evaluated by RT-Real Time, digital qRT-PCR, and dot blot technique. Protein levels were determined by immunohistochemistry, confocal anlysis, western blot techniques, and immunoassay.

RESULTS: We demonstrated that single high-dose irradiation (20 Gy) induces significant tumor growth inhibition in contralateral non-irradiated (NIR) A549 xenograft tumors but not in NIR p53-null H1299 or p53-silenced A549 (A549sh/p53) xenografts. We further demonstrates that irradiation of A549 cells in vitro induces a senescence-associated secretory phenotype (SASP) producing extracellular vesicles (EVs) expressing CD63 and carrying DNA:RNA hybrids and LINE-1 retrotransposon. IR-A549 EVs also hamper the colony-forming capability of recipient NIR A549 cells, induce senescent phenotype, nuclear expression of DNA:RNA hybrids, and M1 macrophage polarization.

CONCLUSIONS: In our models, we demonstrate that high radiation dose in wtp53 tumors induce the onset of SASP and secretion of CD63+ EVs loaded with DNA:RNA hybrids and LINE-1 retrotransposons that convey senescence messages out of the irradiation field triggering abscopal effect in NIR tumors.

Original languageEnglish
Pages (from-to)1-15
Number of pages15
JournalJournal of experimental & clinical cancer research : CR
Issue number1
Publication statusPublished - Mar 5 2021


  • Abscopal effect
  • Non-small cell lung cancer
  • TP53
  • Cellular senescence
  • Extracellular vesicles
  • DNA:RNA hybrids
  • Retrotransposon

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