title: Anti-tumoral effect of the non-nucleoside DNMT inhibitor RG108 in human prostate cancer cells.
abstract: BACKGROUND
  Current therapeutic strategies for advanced prostate cancer (PCa) are largely ineffective. Because aberrant DNA methylation associated with inappropriate gene-silencing is a common feature of PCa, DNA methylation inhibitors might constitute an alternative therapy. In this study we aimed to evaluate the anti-cancer properties of RG108, a novel non-nucleoside inhibitor of DNA methyltransferases (DNMT), in PCa cell lines.
  
  
  METHODS
  The anti-tumoral impact of RG108 in LNCaP, 22Rv1, DU145 and PC-3 cell lines was assessed through standard cell viability, apoptosis and cell cycle assays. Likewise, DNMT activity, DNMT1 expression and global levels of DNA methylation were evaluated in the same cell lines. The effectiveness of DNA demethylation was further assessed through the determination of promoter methylation and transcript levels of GSTP1, APC and RAR-β2, by quantitative methylation-specific PCR and RT-PCR, respectively.
  
  
  RESULTS
  RG108 led to a significant dose and time dependent growth inhibition and apoptosis induction in LNCaP, 22Rv1 and DU145. LNCaP and 22Rv1 also displayed decreased DNMT activity, DNMT1 expression and global DNA methylation. Interestingly, chronic treatment with RG108 significantly decreased GSTP1, APC and RAR-β2 promoter hypermethylation levels, although mRNA reexpression was only attained for GSTP1 and APC.
  
  
  CONCLUSIONS
  RG108 is an effective tumor growth suppressor in most PCa cell lines tested. This effect is likely mediated by reversion of aberrant DNA methylation affecting cancer related-genes epigenetically silenced in PCa. However, additional mechanism might underlie the anti-tumor effects of RG108. In vivo studies are now mandatory to confirm these promising results and evaluate the potential of this compound for PCa therapy.
authors.forename: Inês
authors.initials: I
authors.lastname: Graça
authors.forename: Elsa J
authors.initials: EJ
authors.lastname: Sousa
authors.forename: Tiago
authors.initials: T
authors.lastname: Baptista
authors.forename: Mafalda
authors.initials: M
authors.lastname: Almeida
authors.forename: João
authors.initials: J
authors.lastname: Ramalho-Carvalho
authors.forename: Carlos
authors.initials: C
authors.lastname: Palmeira
authors.forename: Rui
authors.initials: R
authors.lastname: Henrique
authors.affiliation: Department of Genetics & Research Center, Portuguese Oncology Institute - Porto, Rua Dr. António Bernardino de Almeida, 4200-072 Porto, Portugal. cljeronimo@icbas.up.pt.
authors.forename: Carmen
authors.initials: C
authors.lastname: Jerónimo
mesh_terms: D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D045744:Cell Line, Tumor; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000037:antagonists & inhibitors*; D019175:DNA Methylation; D004305:Dose-Response Relationship, Drug; D044127:Epigenesis, Genetic; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D020868:Gene Silencing; D006801:Humans; D008297:Male; D010797:Phthalimides / Q000008:administration & dosage / Q000494:pharmacology*; D011401:Promoter Regions, Genetic; D011471:Prostatic Neoplasms / Q000188:drug therapy* / Q000473:pathology; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D014364:Tryptophan / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: D000970:Antineoplastic Agents; D010797:Phthalimides; C503639:RG108; D012333:RNA, Messenger; D014364:Tryptophan; D004248:DNA (Cytosine-5-)-Methyltransferases