title: Therapy-Induced Cellular Senescence Induces Epithelial-to-Mesenchymal Transition and Increases Invasiveness in Rectal Cancer.
abstract: DNA damaging agents and ionizing radiation used in the therapy of human cancers can induce senescence of cancer cells. Senescent cells exhibit a secretory phenotype (senescence-associated secretome [SAS]) that can affect cancer cell behavior and, eventually, clinical prognosis. We assessed the effects of the SAS on the induction of epithelial-to-mesenchymal transition (EMT) in vitro and in clinical samples from patients with rectal cancer who had undergone neoadjuvant chemoradiotherapy (CRT).
  
  
  
  Colorectal cancer cells (HCT 116) were induced into senescence by exposure to either 5-fluorouracil (5-FU) or doxorubicin. The senescent state was confirmed by staining for senescence-associated β-galactosidase (SA-β-Gal). The paracrine effects of SASs were assessed on proliferating HCT 116 cells. The quantified parameters were cell proliferation, invasive capacity, and induction of EMT. Senescence and EMT in clinical samples were assessed by the expression levels (reverse transcriptase-quantitative polymerase chain reaction) of genes related to senescence and EMT after laser-assisted microdissection of cancer cell clusters that stained either positive or negative for SA-β-Gal.
  
  
  
  We have shown that cultured colon cancer cells induced into senescence by exposure to 5-FU exhibit a SAS capable of paracrine induction of EMT in colon and rectal cancer cell lines and increased cell invasion in vitro. Using laser-assisted microdissection, we found that in rectal cancer samples from patients treated with neoadjuvant CRT, tumor cell niches enriched for senescent cells bookmark regions of increased mRNA expression levels of EMT-related proteins (Slug, Snail, vimentin) compared with the nearby senescent-null tumor cell niches.
  
  
  
  We have provided, first-hand, strongly suggestive evidence that senescent cancer cells emerging in the context of neoadjuvant CRT for rectal cancer influenced the tumor microenvironment by promoting EMT by way of short-range interactions.
authors.affiliation: Instituto de Medicina Molecular, Faculdade de Medicina de Lisboa, Lisboa, Portugal.
authors.forename: Joana
authors.initials: J
authors.lastname: Tato-Costa
authors.affiliation: Instituto de Medicina Molecular, Faculdade de Medicina de Lisboa, Lisboa, Portugal.
authors.forename: Sandra
authors.initials: S
authors.lastname: Casimiro
authors.affiliation: Instituto de Medicina Molecular, Faculdade de Medicina de Lisboa, Lisboa, Portugal.
authors.forename: Teresa
authors.initials: T
authors.lastname: Pacheco
authors.affiliation: Instituto de Medicina Molecular, Faculdade de Medicina de Lisboa, Lisboa, Portugal; Oncology Division, Hospital de Santa Maria, Centro Hospitalar Lisboa Norte, Lisboa, Portugal.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Pires
authors.affiliation: Instituto de Medicina Molecular, Faculdade de Medicina de Lisboa, Lisboa, Portugal.
authors.forename: Afonso
authors.initials: A
authors.lastname: Fernandes
authors.affiliation: Instituto de Medicina Molecular, Faculdade de Medicina de Lisboa, Lisboa, Portugal.
authors.forename: Irina
authors.initials: I
authors.lastname: Alho
authors.affiliation: Instituto de Medicina Molecular, Faculdade de Medicina de Lisboa, Lisboa, Portugal.
authors.forename: Pedro
authors.initials: P
authors.lastname: Pereira
authors.affiliation: Surgery Division, Hospital de Santa Maria, Centro Hospitalar Lisboa Norte, Lisboa, Portugal.
authors.forename: Paulo
authors.initials: P
authors.lastname: Costa
authors.affiliation: Surgery Division, Hospital de Santa Maria, Centro Hospitalar Lisboa Norte, Lisboa, Portugal.
authors.forename: Henrique Bicha
authors.initials: HB
authors.lastname: Castelo
authors.affiliation: Instituto de Medicina Molecular, Faculdade de Medicina de Lisboa, Lisboa, Portugal.
authors.forename: João
authors.initials: J
authors.lastname: Ferreira
authors.affiliation: Instituto de Medicina Molecular, Faculdade de Medicina de Lisboa, Lisboa, Portugal; Oncology Division, Hospital de Santa Maria, Centro Hospitalar Lisboa Norte, Lisboa, Portugal. Electronic address: luiscosta.oncology@gmail.com.
authors.forename: Luís
authors.initials: L
authors.lastname: Costa
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000494:pharmacology*; D016922:Cellular Senescence / Q000187:drug effects*; D004317:Doxorubicin / Q000494:pharmacology; D058750:Epithelial-Mesenchymal Transition / Q000187:drug effects*; D005260:Female; D005455:Fluorescent Antibody Technique; D005472:Fluorouracil / Q000494:pharmacology; D045325:HCT116 Cells; D006801:Humans; D061346:Laser Capture Microdissection; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness / Q000473:pathology; D012004:Rectal Neoplasms / Q000473:pathology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D059016:Tumor Microenvironment
chemical_list: D000970:Antineoplastic Agents; D004317:Doxorubicin; D005472:Fluorouracil
keywords: 5-Fluorouracil; Neoadjuvant chemotherapy; Rectal cancer; Senescence-associated secretory phenotype; Therapy-induced senescence