EMMPRIN Expression by Cultured OSCC and Normal Oral Tissue Cells

Objectives: EMMPRIN (Extracellular Matrix Metalloproteinase Inducer), also known as CD147 or Basigin, is an integral membrane glycoprotein expressed by many types of cells and has a role in many normal and disease processes. EMMPRIN expressed by cancer cells interacts with tumor-associated fibroblasts and promotes production of fibroblast EMMPRIN and matrix metalloproteinases (MMPs), which degrade the tissue extracellular matrix (ECM), facilitating tumor invasion and metastasis. EMMPRIN expression was reported to be elevated in oral squamous cell carcinoma (OSCC) tumor tissue. Objectives: Compare EMMPRIN expression by cultured OSCC and normal oral tissue cell lines to determine whether OSCC cells express high levels of EMMPRIN.
Methods: EMMPRIN was measured in detergent-solubilized extracts of cultured cells and in conditioned media by ELISA using a monoclonal antibody against a site on the EMMPRIN extracellular domain. A line of normal gingival fibroblasts and Smulow-Glickman (S-G) gingival epithelial cells were compared with the Cal27, SCC-25, and SCC-15 lines derived from squamous cell carcinoma of the tongue (ATCC^® CRL-2095, -1628, -1623™, respectively).
Results: EMMPRIN in OSCC cells was lower than in control cells, especially epithelial cells. Values were 60±2, 102±2, 57±1, 50±1, and 41±2 ng/mg protein in extracts from fibroblasts, S-G epithelial cells, and the cancer cells Cal27, SCC-25, and SCC-15, respectively. In contrast, EMMPRIN was higher in conditioned media from OSCC cells. Values were 17±1, 18±1, 37±1, 51±1, and 41±1 ng/mg protein in media from fibroblasts, S-G, Cal27, SCC-25, and SCC-15 cells, respectively.
Conclusions: When cell lines were cultured separately rather than in the mixture of cells found in tumor tissue, EMMPRIN was not expressed at high levels that would make EMMPRIN useful as a cancer biomarker. The major difference between normal and cancer cells was greater release of EMMPRIN from OSCC cells. Released forms of EMMPRIN may be important in signaling fibroblasts to produce EMMPRIN and MMPs.