ALCAM/CD166 is up‐regulated in low‐grade prostate cancer and progressively lost in high‐grade lesions

Abstract

BACKGROUND Activated leukocyte cell adhesion molecule (ALCAM, CD166) is expressed in various tissues, including malignant melanoma, prostate cancer cell lines, and prostate cancer. We aimed to clarify the expression patterns of ALCAM in normal and malignant prostate tissue. METHODS RNA from 54 matched pairs of microdissected prostate tissue (tumor and normal) was hybridized to a custom built 4K GeneChip. Frozen section immunohistochemistry was used to confirm the ALCAM expression. RESULTS Chip‐based transcript analysis revealed an up‐regulation of ALCAM in prostate cancer in 22% of cases. Immunohistochemistry showed a focally raised ALCAM expression in 81% and a decreased expression in 19% of cases. These expression patterns correlated significantly with Gleason tumor grade: ALCAM up‐regulation was found in most low‐grade tumors (Gleason grade 1–3), whereas down‐regulation occurred preferentially in high‐grade tumors (Gleason grade 4 and 5), although up‐regulation of ALCAM expression was preserved in two Gleason grade 5 tumors. CONCLUSION ALCAM expression is commonly disturbed in prostate cancer, which might indicate a role of ALCAM in the progression of this disease. Prostate 54: 34–43, 2003.