Three PCA cell lines, LNCaP, its derivative metastatic C4-2B-2 and highly tumorigenic 22Rv1 lines were selected for this study. The
AMN-107 from all three lines express either a negligible level of or lacking endogenous DLC1 [6] and [9]. LNCaP and 22Rv1 but not C4-2B-2 cells that are metastatic to bone have been previously examined for the epigenetic modifications responsible for DLC1 down regulation. Thus, we decided to reexamine all three lines under identical conditions. DLC1 promoter methylation was detected in LNCaP and C4-2B-2 cells and not in 22Rv1 (Fig. 1A). In our previous study using 22Rv1 cells, direct evidence showing that TSA induced DLC-1 mRNA re-expression is mediated through acetylation of the DLC1 promoter region has been presented [6]. To determine whether promoter methylation was exclusively responsible for DLC1 deregulation in LNCaP and C4-2B-2 cells, we compared the effect of SAHA and TSA on histone acetylation using ChIP assay for two sets of primers from DLC1 promoter region. In all three cell lines, DLC1 specific amplification products of fragments 124 bp and 201 bp were detected in
cells treated with either SAHA or TSA, indicating that DLC1 promoter is both methylated and acetylated in LNCaP and C4-2B-2 cells (Fig. 1B).
