title: Loss of Expression of Reprimo, a p53-induced Cell Cycle Arrest Gene, Correlates with Invasive Stage of Tumor Progression and p73 Expression in Gastric Cancer.
abstract: Reprimo (RPRM), a downstream effector of p53-induced cell cycle arrest at G2/M, has been proposed as a putative tumor suppressor gene (TSG) and as a potential biomarker for non-invasive detection of gastric cancer (GC). The aim of this study was to evaluate the epigenetic silencing of RPRM gene by promoter methylation and its tumor suppressor function in GC cell lines. Furthermore, clinical significance of RPRM protein product and its association with p53/p73 tumor suppressor protein family was explored. Epigenetic silencing of RPRM gene by promoter methylation was evaluated in four GC cell lines. Protein expression of RPRM was evaluated in 20 tumor and non-tumor matched cases. The clinical significance of RPRM association with p53/p73 tumor suppressor protein family was assessed in 114 GC cases. Tumor suppressor function was examined through functional assays. RPRM gene expression was negatively correlated with promoter methylation (Spearman rank r = -1; p = 0.042). RPRM overexpression inhibited colony formation and anchorage-independent growth. In clinical samples, RPRM gene protein expression was detected in 75% (15/20) of non-tumor adjacent mucosa, but only in 25% (5/20) of gastric tumor tissues (p = 0.001). Clinicopathological correlations of loss of RPRM expression were significantly associated with invasive stage of GC (stage I to II-IV, p = 0.02) and a positive association between RPRM and p73 gene protein product expression was found (p<0.0001 and kappa value = 0.363). In conclusion, epigenetic silencing of RPRM gene by promoter methylation is associated with loss of RPRM expression. Functional assays suggest that RPRM behaves as a TSG. Loss of expression of RPRM gene protein product is associated with the invasive stage of GC. Positive association between RPRM and p73 expression suggest that other members of the p53 gene family may participate in the regulation of RPRM expression.
authors.affiliation: Advanced Center for Chronic Diseases (ACCDiS), Pontificia Universidad Católica de Chile, Santiago, Chile; UC-Center for Investigational Oncology (CITO), Pontificia Universidad Católica de Chile, Santiago, Chile; Scientific and Technological Bioresource Nucleus (BIOREN), Centro de Estudios Genéticos e Inmunológicos (CEGIN) and Department of Pathology, Universidad de La Frontera, Temuco, Chile.
authors.forename: Kathleen
authors.initials: K
authors.lastname: Saavedra
authors.affiliation: Department of Pathology, Pontificia Universidad Católica de Chile, Santiago, Chile.
authors.forename: José
authors.initials: J
authors.lastname: Valbuena
authors.affiliation: Advanced Center for Chronic Diseases (ACCDiS), Pontificia Universidad Católica de Chile, Santiago, Chile; UC-Center for Investigational Oncology (CITO), Pontificia Universidad Católica de Chile, Santiago, Chile.
authors.forename: Wilda
authors.initials: W
authors.lastname: Olivares
authors.affiliation: Instituto de Química, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile.
authors.forename: María José
authors.initials: MJ
authors.lastname: Marchant
authors.affiliation: Advanced Center for Chronic Diseases (ACCDiS), Pontificia Universidad Católica de Chile, Santiago, Chile; UC-Center for Investigational Oncology (CITO), Pontificia Universidad Católica de Chile, Santiago, Chile.
authors.forename: Andrés
authors.initials: A
authors.lastname: Rodríguez
authors.affiliation: Advanced Center for Chronic Diseases (ACCDiS), Pontificia Universidad Católica de Chile, Santiago, Chile.
authors.forename: Verónica
authors.initials: V
authors.lastname: Torres-Estay
authors.affiliation: Department of Pathology, Universidad de Chile, Santiago, Chile; Pathology Department Icahn School of Medicine at Mount Sinai, New York, New York, United States of America.
authors.forename: Gonzalo
authors.initials: G
authors.lastname: Carrasco-Avino
authors.affiliation: Instituto de Química, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile.
authors.forename: Leda
authors.initials: L
authors.lastname: Guzmán
authors.affiliation: Virology Program, Institute of Biomedical Sciences, Faculty of Medicine, Universidad de Chile, Santiago, Chile.
authors.forename: Francisco
authors.initials: F
authors.lastname: Aguayo
authors.affiliation: Advanced Center for Chronic Diseases (ACCDiS), Pontificia Universidad Católica de Chile, Santiago, Chile; UC-Center for Investigational Oncology (CITO), Pontificia Universidad Católica de Chile, Santiago, Chile; Department of Pathology, Pontificia Universidad Católica de Chile, Santiago, Chile.
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Roa
authors.affiliation: Advanced Center for Chronic Diseases (ACCDiS), Pontificia Universidad Católica de Chile, Santiago, Chile; UC-Center for Investigational Oncology (CITO), Pontificia Universidad Católica de Chile, Santiago, Chile; Department of Hematology-Oncology, Faculty of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile.
authors.forename: Alejandro H
authors.initials: AH
authors.lastname: Corvalán
mesh_terms: D059447:Cell Cycle Checkpoints / Q000235:genetics*; D018797:Cell Cycle Proteins / Q000235:genetics* / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D019175:DNA Methylation / Q000235:genetics; D004268:DNA-Binding Proteins / Q000378:metabolism*; D018450:Disease Progression; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006023:Glycoproteins / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009687:Nuclear Proteins / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D013274:Stomach Neoplasms / Q000235:genetics* / Q000473:pathology*; D000072160:Tumor Protein p73; D014410:Tumor Stem Cell Assay; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D025521:Tumor Suppressor Proteins / Q000378:metabolism*
chemical_list: D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D006023:Glycoproteins; D009687:Nuclear Proteins; C412566:RPRM protein, human; C000606460:TP73 protein, human; D000072160:Tumor Protein p73; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins