title: Decreased expression of RASSF1A tumor suppressor gene is associated with worse prognosis in clear cell renal cell carcinoma.
abstract: Clear-cell renal cell carcinoma (ccRCC) is the most common subtype of RCC (70-80%) and is associated with poor prognosis in 40% of cases mainly due to metastasis in the course of the disease. RASSF1, with its isoforms RASSF1A and RASSF1C, is a tumor suppressor gene which has not been fully analyzed in ccRCC yet. The epigenetic downregulation of RASSF1A is commonly associated with promoter hypermethylation. The aim of the present study was to compare the ccRCC outcomes with the expression of RASSF1A and RASSF1C. Tissues were obtained from 86 ccRCC patients. RASSF1A and RASSF1C mRNA levels were assessed in tumor and matched normal kidney tissue, and in 12 samples of local metastases by quantitative PCR (qPCR). RASSF1A and RASSF1C proteins levels were semi-quantified in 58 samples by western blot analysis and their tissue localization was assessed by immunohistochemistry. Hypermethylation of RASSF1A promoter was measured by high-resolution-melting methylation-specific qPCR. RASSF1A mRNA levels were 4 and 5 times lower in 66% of tumor and 75% metastasized samples. RASSF1A hypermethylation was found in 40% of analyzed T cases. RASSF1A protein expression was 5 or 20 times decreased in 70% tumor and 75% metastatic samples, respectively. RASSF1A hypermethylation, mRNA and protein levels were associated with TNM progression and higher Fuhrman's grading. Decreased RASSF1A expression, hypermethylation, TNM and Fuhrman's grading were associated with poorer overall survival (OS). Cox hazard ratio (HR) analysis revealed predictor role of RASSF1A mRNA levels on OS and progression-free survival (PFS) in relation to Fuhrman's grading (OS HR=2.25, PFS HR=2.93). RASSF1C levels were increased in ccRCC; no correlations with clinicopathological variables were found. We conclude that RASSF1C gene is not involved in ccRCC progression and we propose that the measurements of RASSF1A mRNA levels in paired tumor-normal kidney tissue could serve as a new prognostic factor in ccRCC.
authors.affiliation: Department of Urology, Faculty of Medicine, Medical University of Gdansk, Gdansk 80-211, Poland.
authors.forename: Jakub
authors.initials: J
authors.lastname: Klacz
authors.affiliation: Department of Histology, Faculty of Medicine, Medical University of Gdansk, Gdansk 80-211, Poland.
authors.forename: Piotr M
authors.initials: PM
authors.lastname: Wierzbicki
authors.affiliation: Department of Histology, Faculty of Medicine, Medical University of Gdansk, Gdansk 80-211, Poland.
authors.forename: Agata
authors.initials: A
authors.lastname: Wronska
authors.affiliation: Department of Histology, Faculty of Medicine, Medical University of Gdansk, Gdansk 80-211, Poland.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Rybarczyk
authors.affiliation: Department of Histology, Faculty of Medicine, Medical University of Gdansk, Gdansk 80-211, Poland.
authors.forename: Marcin
authors.initials: M
authors.lastname: Stanislawowski
authors.affiliation: Department of Histology, Faculty of Medicine, Medical University of Gdansk, Gdansk 80-211, Poland.
authors.forename: Tomasz
authors.initials: T
authors.lastname: Slebioda
authors.affiliation: Department of Histology, Faculty of Medicine, Medical University of Gdansk, Gdansk 80-211, Poland.
authors.forename: Agata
authors.initials: A
authors.lastname: Olejniczak
authors.affiliation: Department of Urology, Faculty of Medicine, Medical University of Gdansk, Gdansk 80-211, Poland.
authors.forename: Marcin
authors.initials: M
authors.lastname: Matuszewski
authors.affiliation: Department of Histology, Faculty of Medicine, Medical University of Gdansk, Gdansk 80-211, Poland.
authors.forename: Zbigniew
authors.initials: Z
authors.lastname: Kmiec
mesh_terms: D000328:Adult; D000368:Aged; D002292:Carcinoma, Renal Cell / Q000235:genetics* / Q000473:pathology / Q000628:therapy; D045744:Cell Line, Tumor; D019175:DNA Methylation / Q000235:genetics*; D018572:Disease-Free Survival; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics; D006801:Humans; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D011379:Prognosis; D011401:Promoter Regions, Genetic; D025521:Tumor Suppressor Proteins / Q000096:biosynthesis* / Q000235:genetics
chemical_list: C411762:RASSF1 protein, human; D025521:Tumor Suppressor Proteins