Activated Leukocyte Cell Adhesion Molecule (ALCAM) is associated with suppression of breast cancer cells invasion

Activated Leukocyte Cell Adhesion Molecule (ALCAM) is expressed in different kinds of normal and neoplastic tissues. Data on the tissue distribution of ALCAM suggest that this protein is involved in tumor progression and metastasis. The lack of available data on ALCAM protein expression in breast cancer prompted us to undertake a study on the involvement of this adhesion molecule in tumor development.

The expressions of ALCAM and reference biomarkers were examined in 56 breast cancer specimens by laser scanning cytometry and confocal microscopy. The results were related to clinical and pathological parameters, i.e. histological grade, tumor diameter, lymph node involvement, NPI, steroid receptor (estrogen, ER, and progesterone, PgR) expression, and HER2/neu over-expression.

High levels of ALCAM significantly correlated with small tumor diameter (p=0.009), low tumor grade (p=0.001), and the presence of progesterone (p=0.009) and estrogen (p=0.006) receptors. Declining ALCAM concentrations correlated with HER2/neu gene amplification, inasmuch as the obtained p value, 0.065, was very close to the established statistical significance level of p=0.05. The ALCAM/MMP-2 ratio was significantly higher in cancer cases characterized by small tumor size (p=0.04) and low tumor grade (p=0.022).

Analysis of ALCAM expression in relation to other molecular biomarkers revealed that ALCAM expression and the ALCAM/MMP-2 ratio are more promising indicators of breast cancer progression than MMP-2, E-cadherin, and alpha-catenin. Low ALCAM concentration correlated with an aggressive tumor phenotype, which supports the view that this adhesion molecule is a tumor suppressor marker with prognostic significance.