title: Loss of p16(INK4a) is associated with reduced patient survival in soft tissue tumours, and indicates a senescence barrier.
abstract: OBJECTIVE
  p16(INK4a) is an important factor in carcinogenesis, and its expression is linked to oncogene-induced senescence. Very recently it was shown that upregulation and downregulation of p16 indicates a senescence barrier in the serrated route of colorectal cancer. However, in soft tissue sarcoma (STS), the senescence mechanism is still not understood. In this study, we analysed a well characterised cohort of STS for p16(INK4a) expression and correlated the results with clinicopathological parameters including survival.
  
  
  METHODS
  Tissue microarrays (TMA) of 183 soft tissue and bone tumours were analysed immunohistochemically. Furthermore, mRNA expression of p16(INK4a) was evaluated in four sarcoma cell lines, and a demethylation test was performed by treatment with 5-aza-2'-deoxycytide.
  
  
  RESULTS
  On protein level, expression of p16(INK4a) was observed in undifferentiated pleomorphic sarcoma (UPS) in 69.1%, leiomyosarcoma in 85.7%, synovial sarcoma in 77.8%, liposarcoma in 88.9%, angiosarcoma in 60.9% and MPNST in 22.2%. Loss of p16(INK4a) was observed in high grade sarcomas and showed a significant correlation with reduced patient survival (p=0.032). On DNA level, one out of four sarcoma cell lines exhibited a methylated p16(INK4a) promoter analysed by methylation-specific PCR. p16(INK4a) mRNA and protein expression was restored after demethylation using 5-aza-2'-deoxycytide.
  
  
  CONCLUSIONS
  Upregulation of p16(INK4a) might be associated with the induction of senescence and indicates a senescence barrier. Downregulation of p16(INK4a) is found in malignant progression, and is significantly correlated with reduced patient survival. Downregulation of p16(INK4a) may be explained by DNA-hypermethylation in sarcoma cells.
authors.affiliation: Institute of Pathology, Ludwig-Maximilians-University (LMU), Munich, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Knösel
authors.affiliation: Department of General, Visceral und Vascular Surgery, Friedrich-Schiller University, Jena, Germany.
authors.forename: Annelore
authors.initials: A
authors.lastname: Altendorf-Hofmann
authors.affiliation: Department of Internal Medicine III, Ludwig-Maximilians-University (LMU), Munich, Germany.
authors.forename: Lars
authors.initials: L
authors.lastname: Lindner
authors.affiliation: Department of Internal Medicine III, Ludwig-Maximilians-University (LMU), Munich, Germany.
authors.forename: Rolf
authors.initials: R
authors.lastname: Issels
authors.affiliation: Experimental and Molecular Pathology, Institute of Pathology, Ludwig-Maximilians-University (LMU), Munich, Germany.
authors.forename: Heiko
authors.initials: H
authors.lastname: Hermeking
authors.affiliation: Department of Internal Medicine III, Ludwig-Maximilians-University (LMU), Munich, Germany.
authors.forename: Gesa
authors.initials: G
authors.lastname: Schuebbe
authors.affiliation: Department of Internal Medicine III, Ludwig-Maximilians-University (LMU), Munich, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Gibis
authors.affiliation: Experimental and Molecular Pathology, Institute of Pathology, Ludwig-Maximilians-University (LMU), Munich, Germany.
authors.forename: Helge
authors.initials: H
authors.lastname: Siemens
authors.affiliation: Department of Internal Medicine III, Ludwig-Maximilians-University (LMU), Munich, Germany.
authors.forename: Eric
authors.initials: E
authors.lastname: Kampmann
authors.affiliation: Institute of Pathology, Ludwig-Maximilians-University (LMU), Munich, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Kirchner
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D016922:Cellular Senescence; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000235:genetics / Q000378:metabolism*; D019175:DNA Methylation; D015536:Down-Regulation; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D012307:Risk Factors; D012509:Sarcoma / Q000235:genetics / Q000378:metabolism* / Q000401:mortality / Q000473:pathology; D012983:Soft Tissue Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000401:mortality / Q000473:pathology; D046888:Tissue Array Analysis; D055815:Young Adult
chemical_list: D014408:Biomarkers, Tumor; D019941:Cyclin-Dependent Kinase Inhibitor p16; D012333:RNA, Messenger
keywords: Molecular Pathology; Soft Tissue Tumours; Tumour Biology