Identification of PMF1 methylation in association with bladder cancer progression.
OBJECTIVE
Polyamines are important regulators of cell growth and death. The polyamine modulated factor-1 (PMF-1) is involved in polyamine homeostasis. After identifying an enriched CpG island encompassing the PMF1 promoter, we aimed at evaluating the clinical relevance of PMF1 methylation in bladder cancer.


METHODS
The epigenetic silencing of PMF1 by hypermethylation was tested in bladder cancer cells (n = 11) after azacytidine treatment. PMF1 methylation status was evaluated in 507 bladder tumors and 118 urinary specimens of bladder cancer patients and controls. PMF1 protein expression was analyzed by immunohistochemistry on tissue arrays containing bladder tumors for which PMF1 methylation was assessed (n = 218).


RESULTS
PMF1 hypermethylation was associated with gene expression loss, being restored in vitro by a demethylating agent. An initial set of 101 primary frozen bladder tumors served to identify PMF1 hypermethylation in 88.1% of the cases. An independent set of 406 paraffin-embedded tumors also revealed a high PMF1 methylation rate (77.6%). PMF1 methylation was significantly associated with increasing stage (P = 0.025). Immunohistochemical analyses revealed that PMF1 methylation was associated with cytoplasmic PMF1 expression loss (P = 0.032). PMF1 protein expression patterns were significantly associated with stage (P < 0.001), grade (P < 0.001), and poor overall survival using univariate (P < 0.001) and multivariate (P = 0.011) analyses. Moreover, PMF1 methylation in urinary specimens distinguished bladder cancer patients from controls (area under the curve = 0.800).


CONCLUSIONS
PMF1 was identified to be epigenetically modified in bladder cancer. The association of PMF1 methylation with tumor progression and its diagnostic ability using urinary specimens support including PMF1 assessment for the clinical management of bladder cancer patients.
Aleman
Ainel
A
Tumor Markers Group, Molecular Pathology Program, Spanish National Cancer Center, Madrid, Spain.
Cebrian
Virginia
V
Alvarez
Miguel
M
Lopez
Virginia
V
Orenes
Esteban
E
Lopez-Serra
Lidia
L
Algaba
Ferran
F
Bellmunt
Joaquin
J
López-Beltrán
Antonio
A
Gonzalez-Peramato
Pilar
P
Cordon-Cardo
Carlos
C
García
Javier
J
del Muro
Javier García
JG
Esteller
Manel
M
Sánchez-Carbayo
Marta
M
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019175:DNA Methylation; D018450:Disease Progression; D044127:Epigenesis, Genetic; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D014157:Transcription Factors / Q000235:genetics*; D001749:Urinary Bladder Neoplasms / Q000235:genetics*
C120655:PMF1 protein, human; D014157:Transcription Factors