DNA demethylation and histone deacetylation inhibition co-operate to re-express estrogen receptor beta and induce apoptosis in prostate cancer cell-lines.
BACKGROUND
Epigenetic silencing mechanisms are increasingly thought to play a major role in the development of human cancers, including prostate cancer. Promoter CpG island hypermethylation and histone hypoacetylation, catalyzed by DNA methyltransferase (DNMT) and histone deacetylase (HDAC), respectively, are associated with transcriptional repression in a number of cancers. Evidence is accumulating the two mechanisms are dynamically linked, yet few studies have examined a potential interaction in prostate cancer.


METHODS
LNCaP, DU-145, and PC-3 prostate cancer cells were co-treated with a DNMT inhibitor, 5'-aza-2'-deoxycytidine (5-AZAC), and an HDAC inhibitor, trichostatin A (TSA). Following treatment cells were processed for cell proliferation/apoptosis assays, or harvested for real-time RT-PCR. Assessed target genes were estrogen receptor beta (ERbeta), estrogen receptor alpha (ERalpha), androgen receptor (AR), progesterone receptor (PGR), and prostate specific antigen (PSA).


RESULTS
In all cell-lines, co-treatment was associated with reduced cell proliferation compared with control groups (P<0.05). A reciprocal rise in caspase activation was identified, indicating apoptosis was the major mechanism of cell death. Most marked effects were seen in the androgen-dependent, AR-positive LNCaP cell-line. In all cell-lines, an additive re-expression of ERbeta was identified in the co-treatment group, a finding not seen for either AR or PSA.


CONCLUSIONS
At concentrations associated with gene re-expression, the DNA demethylating agent 5-AZAC and the HDAC inhibitor TSA co-operate to induce apoptosis in prostate cancer cell-lines. Increased apoptosis in the co-treatment group was associated with marked re-expression of ERbeta, raising the possibility of further targeting of prostate cancer cells with ERbeta-selective agents.
Walton
T J
TJ
Interdisciplinary Biomedical Research Centre, Department of Biomedical and Natural Sciences, Nottingham Trent University, Nottingham, United Kingdom. tjwalton1974@btinternet.com
Li
G
G
Seth
R
R
McArdle
S E
SE
Bishop
M C
MC
Rees
R C
RC
D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D001374:Azacitidine / Q000031:analogs & derivatives / Q000494:pharmacology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D019175:DNA Methylation / Q000187:drug effects; D015254:DNA Modification Methylases / Q000037:antagonists & inhibitors*; D000077209:Decitabine; D004791:Enzyme Inhibitors / Q000494:pharmacology; D047628:Estrogen Receptor alpha / Q000378:metabolism; D047629:Estrogen Receptor beta / Q000378:metabolism*; D056572:Histone Deacetylase Inhibitors; D006657:Histones / Q000187:drug effects; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology; D008297:Male; D017430:Prostate-Specific Antigen / Q000378:metabolism; D011471:Prostatic Neoplasms / Q000378:metabolism* / Q000473:pathology*; D011944:Receptors, Androgen / Q000378:metabolism; D011980:Receptors, Progesterone / Q000378:metabolism
D004791:Enzyme Inhibitors; D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D056572:Histone Deacetylase Inhibitors; D006657:Histones; D006877:Hydroxamic Acids; D011944:Receptors, Androgen; D011980:Receptors, Progesterone; C012589:trichostatin A; D000077209:Decitabine; D015254:DNA Modification Methylases; D017430:Prostate-Specific Antigen; D001374:Azacitidine