Activated leukocyte cell adhesion molecule (ALCAM/CD166) expression in head and neck squamous cell carcinoma (HNSSC)

Activated leukocyte cell adhesion molecule (ALCAM/CD166) is expressed in a number of malignancies (e.g. prostate, breast, squamous cell carcinoma of the esophagus, lung and head and neck tumors). Based on studies in which ALCAM showed prognostic relevance in several carcinomas, it has been discussed as a potential therapeutic target. We evaluate its expression in head and neck squamous cell carcinomas (HNSCCs). A tissue microarray was constructed from more than 400 HNSCCs. Slides were analyzed by immunohistochemistry for ALCAM. Membranous and cytoplasmic ALCAM positivity were rated separately. The tumors were combined into (a) cases with membranous staining and (b) cases with cytoplasmic staining, independently from membranous/cytoplasmic co-expression. We found staining in 70.3% of interpretable HNSCCs. Pure membranous staining was found in 12.4% of tumors, with cytoplasmic positivity in 40.1% of cases, and membranous/cytoplasmic co-expression in 17.9%. No significant association between ALCAM positivity and clinical parameters was found. No significant association between ALCAM expression and survival data was observed for all tumors. The frequent expression of ALCAM (70.3%) in head and neck squamous cell carcinomas does not support an important role for HNSCC biology. The increased levels of ALCAM suggest the existence of a therapeutic window for potential anti-ALCAM therapies.