title: DNMT1 silencing affects locus specific DNA methylation and increases prostate cancer derived PC3 cell invasiveness.
abstract: OBJECTIVE
  DNMT1 maintains genomic DNA methylation at 5'-CpG-3' residues in somatic cells. Recent findings revealed that DNMT1 depletion causes distinct phenotypic changes in colon and gastric cancer cell lines, suggesting that the extent to which DNMT1 influences the expression of its target genes is cell-type specific. We determined the impact of DNMT1 depletion in prostate cancer derived cells on their gene expression profiles and cellular phenotype.
  
  
  METHODS
  Small interfering RNA was used to silence DNMT1 expression in prostate cancer derived PC3 cells (ATCC). The resulting cell line was validated by reverse transcriptase-polymerase chain reaction and Western blotting. Proliferation, migration and invasion assays were done in engineered cells to asses the effect of DNMT1 silencing on cellular phenotype. DNA microarrays were done to monitor changes in gene expression.
  
  
  RESULTS
  Our data showed that DNMT1 loss dramatically decreased cell proliferation but significantly increased cell migratory and invasive potential. Additionally, in the limited set of genes whose expression and DNA methylation status were determined DNMT1 loss was associated with increased CDKN3 and claudin-3 expression, and also culminated in specific demethylation of Rb1 and RAR-beta promoters.
  
  
  CONCLUSIONS
  These results show that the genetic and phenotypic consequences of silencing DNMT1 in PC3 cells are markedly different from those in colon and gastric cancers, indicating that DNMT1 preferentially targets certain gene promoters. Our findings also suggest that decreasing DNMT1 levels or activity can potentially enhance prostate cancer cell invasiveness.
authors.affiliation: Department of Biological and Biomedical Sciences, Aga Khan University, Karachi, Pakistan.
authors.forename: Ahmed
authors.initials: A
authors.lastname: Yaqinuddin
authors.forename: Sohail A
authors.initials: SA
authors.lastname: Qureshi
authors.forename: Romena
authors.initials: R
authors.lastname: Qazi
authors.forename: Salman
authors.initials: S
authors.lastname: Farooq
authors.forename: Farhat
authors.initials: F
authors.lastname: Abbas
mesh_terms: D045744:Cell Line, Tumor; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000235:genetics*; D019175:DNA Methylation; D020868:Gene Silencing; D006801:Humans; D008297:Male; D009361:Neoplasm Invasiveness; D011471:Prostatic Neoplasms / Q000235:genetics* / Q000473:pathology*
chemical_list: D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases; C000619380:DNMT1 protein, human