Expression and importance of inhibitor of DNA binding helix-loop-helix protein in salivary adenoid cystic carcinoma

Studies have reported that Id-1 (inhibitor of DNA binding, or differentiation 1) protein, helix-loop-helix (HLH) transcription factor, has important roles in the development of several carcinomas. However, the role of Id-1 protein in salivary adenoid cystic carcinoma (ACC) is not clear. The expression of Id-1 protein was assessed in formalin-fixed, paraffin-embedded surgical specimens of ACCs by immunohistochemical staining. Thirty-nine of the 54 specimens of ACC stained for Id-1expression, which was significantly more than was found in pleomorphic adenomas (4/12) and normal salivary gland tissues (1/10, p < 0.05). There were also significant differences between stages I and II (7/14) and III-IV (32/40) (p < 0.05). Of tumours with metastases, 31/38 stained for Id-1, which was significantly higher than among those without metastases (8/16) (p < 0.05). Our results showed that Id-1 may have important roles in the development of salivary ACC. It might also be a useful therapeutic tool to help prevent salivary ACC or to inhibit its malignant progression.