CpG hypermethylation of human four-and-a-half LIM domains 1 contributes to migration and invasion activity of human bladder cancer

Abstract

Abstract. We previously reported a simple technique that combines microarray data from clinical bladder cancer (BC) specimens with those from a BC cell line (BOY) treated with a pharmacologic demethylating agent (5-aza-dC). We focused on the human four-and-a-half LIM domains 1 (FHL1) gene which was selected on the basis of previous microarray data analysis. Because LIM domains provide protein-protein binding interfaces, FHL genes play an important role in cellular events, such as focal adhesion and differentiation, by interacting with the target protein as either a repressor or activator. We hypothesized that inactivation of the FHL1 gene through CpG methylation contributes to cell viability including migration and invasion activity of human BC. After 5-aza-dC treatment, the expression levels of FHL1 mRNA transcript markedly increased in all cell lines tested, as shown by real-time reverse transcription-polymerase chain reaction (RT-PCR). The methylation index of FHL1 in our samples was significantly higher in 70 BC specimens than in 10 normal bladder epithelium (NBE) specimens (63.9±25.5 and 0.3±0.2, respectively; p=0.0066). Conversely, FHL1 mRNA expression was significantly lower in the BC specimens than in the NBE ones (0.331±0.12 and 2.498±0.61, respectively; p=0.0011). In addition, significant inhibitions of wound healing (45.78±6.2, and 100±0, respectively; p=0.009) and of cell invasion (18.5±2.3 and 95.2±2.4, respectively; p=0.02) were observed in stable FHL1-transfected cells than in the control BC cells. In conclusion, we found that the mechanism of FHL1 down-regulation in BC is through CpG hypermethylation of the promoter region. FHL1 gene inactivation by CpG hypermethylation may thus contribute to migration and invasion activity of BC.

FHL1 Inhibits the Progression of Colorectal Cancer by Regulating the Wnt/β-Catenin Signaling Pathway

“…These results are consistent with those of previous studies showing that FHL1 inhibits the proliferation of lung cancer cells in vitro 9 . Studies in oral cancer and bladder cancer have also found that reduced expression of FHL1 promotes tumor progression and is associated with poor prognosis 10 , 23 . These studies strongly suggest that FHL1 plays an anticancer role in the proliferation of a variety of tumor types.…”