Background. Activated Leukocyte Cell Adhesion Molecule, ALCAM (also known as CD166) is a member of the immunoglobulin superfamily and a cell surface adhesion molecule involved in heterophilic and homophilic interactions during cell-cell adhesion in epithelial cells, cancer cells and endothelial cells. ALCAM appears to be linked to tumour progression in a number of cancers including breast cancer, though there are conflicting reports as to its precise prognostic implications and significance. We have previously reported that ALCAM has a tumour suppressive role in breast cancer and is inversely correlated with clinical outcome (1) and interestingly bone metastasis of breast cancer (2). We have also reported that ALCAM has a diverse role in other cell types including keratinocytes and endothelial cells. In the present study, we investigated the association between ALCAM and hepatocyte growth factor (HGF)/cMET, a signalling pathway established as a key promoter of cancer progression, influencing both the aggressive nature of cancer cells and acting as an angiogenic and lymphangiogenic factor, in breast cancer and endothelial cells.

Methods. The expression pattern and correlation of ALCAM, HGF and cMET in human breast cancer were deduced from a clinical breast cancer cohort. ALCAM manipulated HECV cell lines, previously established in our laboratories, were used in conjunction with recombinant human HGF and cMET inhibitors to assess cellular functions and the implications of this relationship at a cellular level.

Results. We compared the expression of ALCAM with that of HGF and cMET within the breast cancer cohort and found that ALCAM/CD166 showed a highly significant negative correlation with the HGF receptor cMET (r=-0.17, p<0.0001) and a weak negative correlation with HGF, although this was not significant. ALCAM was not found to correlate with its heterophilic partner CD6. In previously generated HECV models, ALCAM manipulation showed a marked influence on cellular function and responsiveness to HGF treatment.

Discussion. ALCAM’s role in breast cancer progression and related mechanisms is complex. Our current data suggests this may involve an interaction with the cMET/HGF signalling pathway and may also impact the endothelial component within the tumour microenvironment to influence disease progression.

Reference1 King JA, Ofori-Acquah SF, Stevens T, et al. Activated leukocyte cell adhesion molecule in breast cancer: prognostic indicator. Breast Cancer Res. 2004;6:R478-87.

Reference2 Davies SR, Dent C, Watkins G et al. Expression of the cell to cell adhesion molecule, ALCAM, in breast cancer patients and the potential link with skeletal metastasis. Oncol Rep. 2008;19:555-61.

Citation Format: Andrew James Sanders, David Guo Jiang, Jianyuan Zeng, Robert Edward Mansel, Eleri Davies, Amber Xinyu Li, Keith Gordon Harding, Wen Guo Jiang. Potential role of activated leukocyte cell adhesion molecule (ALCAM) in hepatocyte growth factor (HGF) signalling in vascular endothelial cells and implications in breast cancer [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS17-48.