CLCA2, a target of the p53 family, negatively regulates cancer cell migration and invasion

The tumor suppressor p53 transcriptionally regulates a number of genes that are involved in cell-cycle inhibition, apoptosis and the maintenance of genetic stability. Recent studies suggest that p53 also contributes to the regulation of cell migration and invasion. Here, we show that human chloride channel accessory-2 (CLCA2) is a target gene of the p53 family (p53, p73 and p63). CLCA2 is induced by DNA damage in a p53-dependent manner. The p53 family proteins activate the CLCA2 promoter by binding directly to the conserved consensus p53-binding site present in the CLCA2 promoter. In terms of function, ectopic expression of CLCA2 inhibited cancer cell migration. In contrast, silencing CLCA2 with siRNA stimulated cancer cell migration and invasion. We also found that inactivation of CLCA2 enhanced the expression of focal adhesion kinase (FAK), as well as its promoter activation. A small-molecule FAK inhibitor reduced the effect of CLCA2 siRNA on cell migration and invasion, suggesting that CLCA2 inhibits cancer cell migration and invasion through suppression of the FAK signaling pathway. Furthermore, there was an inverse correlation between CLCA2 and FAK expression in 251 human breast cancer tissues. These results strongly suggest that CLCA2 is involved in the p53 tumor suppressor network and has a significant effect on cell migration and invasion.