TY - JOUR
T1 - Activation of silenced tumor suppressor genes in prostate cancer cells by a novel energy restriction-mimetic agent
AU - Lin, Hsiang Yu
AU - Kuo, Yi Chiu
AU - Weng, Yu I.
AU - Lai, I. Lu
AU - Huang, Tim H.M.
AU - Lin, Shuan Pei
AU - Niu, Dau Ming
AU - Chen, Ching Shih
PY - 2012/12/1
Y1 - 2012/12/1
N2 - Background. Targeting tumor metabolism by energy restriction-mimetic agents (ERMAs) has emerged as a strategy for cancer therapy/prevention. Evidence suggests a mechanistic link between ERMA-mediated antitumor effects and epigenetic gene regulation. Methods. Microarray analysis showed that a novel thiazolidinedione-derived ERMA, CG-12, and glucose deprivation could suppress DNA methyltransferase (DNMT)1 expression and reactivate DNA methylation-silenced tumor suppressor genes in LNCaP prostate cancer cells. Thus, we investigated the effects of a potent CG-12 derivative, CG-5, vis-À-vis 2-deoxyglucose, glucose deprivation and/or 5-aza-deoxycytidine, on DNMT isoform expression (Western blotting, RT-PCR), DNMT1 transcriptional activation (luciferase reporter assay), and expression of genes frequently hypermethylated in prostate cancer (quantitative real-time PCR). Promoter methylation was assessed by pyrosequencing analysis. SiRNA-mediated knockdown and ectopic expression of DNMT1 were used to validate DNMT1 as a target of CG-5. Results. CG-5 and glucose deprivation upregulated the expression of DNA methylation-silenced tumor suppressor genes, including GADD45a, GADD45b, IGFBP3, LAMB3, BASP1, GPX3, and GSTP1, but also downregulated methylated tumor/invasion-promoting genes, including CD44, S100A4, and TACSTD2. In contrast, 5-aza-deoxycytidine induced global reactivation of these genes. CG-5 mediated these epigenetic effects by transcriptional repression of DNMT1, which was associated with reduced expression of Sp1 and E2F1. SiRNA-mediated knockdown and ectopic expression of DNMT1 corroborated DNMT1's role in the modulation of gene expression by CG-5. Pyrosequencing revealed differential effects of CG-5 versus 5-aza-deoxycytidine on promoter methylation in these genes. Conclusions. These findings reveal a previously uncharacterized epigenetic effect of ERMAs on DNA methylation-silenced tumor suppressor genes, which may foster novel strategies for prostate cancer therapy.
AB - Background. Targeting tumor metabolism by energy restriction-mimetic agents (ERMAs) has emerged as a strategy for cancer therapy/prevention. Evidence suggests a mechanistic link between ERMA-mediated antitumor effects and epigenetic gene regulation. Methods. Microarray analysis showed that a novel thiazolidinedione-derived ERMA, CG-12, and glucose deprivation could suppress DNA methyltransferase (DNMT)1 expression and reactivate DNA methylation-silenced tumor suppressor genes in LNCaP prostate cancer cells. Thus, we investigated the effects of a potent CG-12 derivative, CG-5, vis-À-vis 2-deoxyglucose, glucose deprivation and/or 5-aza-deoxycytidine, on DNMT isoform expression (Western blotting, RT-PCR), DNMT1 transcriptional activation (luciferase reporter assay), and expression of genes frequently hypermethylated in prostate cancer (quantitative real-time PCR). Promoter methylation was assessed by pyrosequencing analysis. SiRNA-mediated knockdown and ectopic expression of DNMT1 were used to validate DNMT1 as a target of CG-5. Results. CG-5 and glucose deprivation upregulated the expression of DNA methylation-silenced tumor suppressor genes, including GADD45a, GADD45b, IGFBP3, LAMB3, BASP1, GPX3, and GSTP1, but also downregulated methylated tumor/invasion-promoting genes, including CD44, S100A4, and TACSTD2. In contrast, 5-aza-deoxycytidine induced global reactivation of these genes. CG-5 mediated these epigenetic effects by transcriptional repression of DNMT1, which was associated with reduced expression of Sp1 and E2F1. SiRNA-mediated knockdown and ectopic expression of DNMT1 corroborated DNMT1's role in the modulation of gene expression by CG-5. Pyrosequencing revealed differential effects of CG-5 versus 5-aza-deoxycytidine on promoter methylation in these genes. Conclusions. These findings reveal a previously uncharacterized epigenetic effect of ERMAs on DNA methylation-silenced tumor suppressor genes, which may foster novel strategies for prostate cancer therapy.
KW - DNA methyltransferases
KW - energy restriction
KW - energy restriction-mimetic agent
KW - epigenetics
KW - prostate cancer
UR - http://www.scopus.com/inward/record.url?scp=84867884641&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84867884641&partnerID=8YFLogxK
U2 - 10.1002/pros.22530
DO - 10.1002/pros.22530
M3 - Article
C2 - 22539223
AN - SCOPUS:84867884641
SN - 0270-4137
VL - 72
SP - 1767
EP - 1778
JO - Prostate
JF - Prostate
IS - 16
ER -