Effects of silencing Id-1 in cell culture of human adenoid cystic carcinoma.

Adenoid cystic carcinoma (ACC) is a slow growing but highly invasive cancer with a high recurrence rate. Id (inhibitor of DNA binding) proteins are dominant regulators of basic helix-loop-helix transcription factors that control malignant cell behavior in many different tissues. This study aimed to identify the potential role of inhibiting DNA binding-1 (Id-1) in human salivary adenoid cystic carcinoma (SACC) progression. First, we compared the Id-1 protein expression in a human salivary adenoid cystic carcinoma cell line (ACCM) against three other cell lines and found that Id-1 protein expression in ACCM to be significantly higher. Then we measured Id-1 mRNA and protein expression in ACCM before and after RNA interference (RNAi), which showed successful inhibition of Id-1. Further studies then demonstrated that the proliferation and invasiveness of ACCM cells were dramatically down-regulated, and increased numbers of apoptotic cells were detected after Id-1 silencing. Consequently, our data suggest that Id-1 is a potential target in the treatment of human salivary adenoid cystic carcinoma.