Prostate cancer is characterized by epigenetic silencing of 14-3-3sigma expression.
In order to identify tumor suppressive genes silenced by CpG methylation in prostate carcinoma (PCa), we determined genome-wide expression changes after pharmacological reversal of CpG methylation-mediated transcriptional repression in three PCa cell lines using microarray analysis. Thereby, epigenetic silencing of the 14-3-3sigma gene was detected in the cell line LNCaP. 14-3-3sigma encodes a p53-regulated inhibitor of cell cycle progression. Laser microdissection was used to isolate different cell types present in diseased prostatic tissue. Subsequent methylation-specific PCR analysis showed CpG methylation of 14-3-3sigma in all 41 primary PCa samples analysed, which was accompanied by a decrease or loss of 14-3-3sigma protein expression. In contrast, normal prostate epithelial and benign prostate hyperplasia cells showed high levels of 14-3-3sigma expression. PCa-precursor lesions (prostatic intraepithelial neoplasia) also displayed decreased levels of 14-3-3sigma expression in luminal cells, which are known to contain shortened telomeres. RNA interference-mediated inactivation of 14-3-3sigma compromised a DNA damage-induced G(2)/M arrest in the PCa cell line PC3. The generality of CpG methylation and downregulation of 14-3-3sigma expression in PCa suggests that it significantly contributes to the formation of PCa, potentially by allowing the escape from a DNA damage-induced arrest elicited by telomere shortening.
Molecular Oncology, Max-Planck-Institute of Biochemistry, Am Klopferspitz 18, D-82152 Martinsried/Munich, Germany.
Dimitri
D
Lodygin
Joachim
J
Diebold
Heiko
H
Hermeking
D048948:14-3-3 Proteins; D001483:Base Sequence; D014408:Biomarkers, Tumor / Q000235:genetics*; D045744:Cell Line, Tumor; D018899:CpG Islands; D019175:DNA Methylation; D017931:DNA Primers; D015536:Down-Regulation; D044127:Epigenesis, Genetic; D005092:Exonucleases / Q000235:genetics*; D005095:Exoribonucleases; D020868:Gene Silencing; D006801:Humans; D008297:Male; D009363:Neoplasm Proteins / Q000235:genetics*; D020411:Oligonucleotide Array Sequence Analysis; D011471:Prostatic Neoplasms / Q000235:genetics* / Q000473:pathology; D034622:RNA Interference; D020133:Reverse Transcriptase Polymerase Chain Reaction
D048948:14-3-3 Proteins; D014408:Biomarkers, Tumor; D017931:DNA Primers; D009363:Neoplasm Proteins; D005092:Exonucleases; D005095:Exoribonucleases; C413442:SFN protein, human