No abstract

The aberrant expression of cell adhesion molecules (CAMs) is correlated with the malignant progression of many tumors. MUC18/CD146/A32/MelCAM/S-endo, an integral membrane glycoprotein, is a CAM in the immunoglobulin gene superfamily. MUC18 has often been mistaken as a mucin because of the misleading nomenclature. Based on its biological functions and other known biochemical properties, we propose to re-name it as METCAM (metastasis CAM). METCAM/MUC18 expression has a very interesting effect on tumor formation and metastasis. The overexpression of METCAM/MUC18 has been correlated with the malignant progression of human melanoma and human prostate cancer. In melanoma, the ectopic over-expression of METCAM/MUC18 has no effect on tumorigenesis, but augments the metastasis of cancer cells. In prostate cancer, the ectopic over-expression of human METCAM/MUC18 has an even greater effect, increasing tumorigenesis and initiating the metastasis of cancer cells. However, an opposite effect of METCAM/MUC18 on tumorigenesis and metastasis of breast cancer, some mouse melanoma cell lines, and perhaps haemangioma and nasopharygeal carcinoma has also been suggested. Taken together, we suggest that the different effect of METCAM/MUC18 on tumor formation and metastasis is dependent on the intrinsic properties of each tumor cell line. This paper will review previous experiments and results and present some possible mechanisms of METCAM/MUC18-mediated tumorigenesis and metastasis for future studies.

No abstract

We therefore conclude that MUC18 is expressed at higher levels in pre-malignant and malignant prostatic epithelium, including metastasis. We suggest that over-expression of MUC18 may be a new marker of human prostate cancer and also implicates its possible role in development and progression of prostate cancer.

Enforced expression of human metastasis cell adhesion molecule/MUC18 increases prostate tumorigenesis in vivo and may affect the process by increasing proliferation, up-regulating the AKT survival pathway, and augmenting the angiogenic ability of prostate cancer cells.