Soluble CD147Promotes MMP-2Expression In Hepatocellular Carcinoma Cells

Cancer is one of the biggest threats to human’s health. The consistentproliferation of cancer cells after tumorigenesis, and their invasion andmigration are the main reasons causing death. During the process of invasionand migration of cancer cells, the microenvironment around plays an importantrole. Various types of cells including fibroblasts assistant the invasion andmigration through different ways, one of the most important mechanism issynthesis of matrix metalloproteinases (MMPs) which can degrade extracellularmatrix. After degradation of the matrix around the cancer cells, the restriction tothe cancer cells will be relieved, this leads to the migration of cancer. There aremany inducers for MMPs, whereas CD147is one of the most importantmolecules in the cells, named extracellular matrixmetalloprteinase inducer(EMMPRIN). CD147is a single transmembrane protein which at the very beginning was discovered that it could induce the upregulation of MMPs in thefibroblasts after co-culture with the CD147-expressed cells.The soluble CD147was discovered in the culture medium of cancer cells.There are two types of soluble CD147, the full length CD147which is the sameas the molecule expressed on the cell membrane, which is estimated that it issecreted from the cells or released from the cell membrane. Another type is theextracellular portion of CD147, which is estimated that it is shedding by enzyme.Soluble CD147could contact with the membrane type CD147，which couldinduce the MMPs secretion increasing. This study is to detect the type of CD147expressed on the HCC cells, and their effect on the secretion of MMPs in HCCcells, and to elucidate the function of soluble CD147in inducing MMPs.Part Ⅰ: Soluble and membrane CD147expression in HCC cell lineSMMC-7721.We discovered the upregulation of CD147in the SMMC-7721bywestern-blot and immunoflorescent. The protein in the culture supernatant ofSMMC-7721cells was precipitated by acetone precipitation. By western-blotanalysis the soluble CD147was found and showing the samilar molecularweight with the high-glycosylation of membrane-type CD147. The solubleCD147contained the intracellular domain as shown by reaction with antibodyagainst intracellular domain of CD147.Part Ⅱ: The role of soluble CD147on the MMPs expression in SMMC-7721cells.In order to validate which domain of soluble CD147mediates theupregulation of MMP-2expression in HCC, we used recombinant extracellulardomain and intracellular domain of CD147expressed by eukaryotic cells tostimulate the cells respectively, and detected the MMP-2expression level. We found that soluble CD147promoted MMP-2expression, which was mediated bythe extracellular domain of soluble CD147molecule. Next, we usedrecombinant extracellular domain of soluble CD147stimulated the cells todetect the different types of MMP expression. We found that after stimulation,the expression level of MMP-2molecule in hepatocellular carcinoma cellsraised statistically significant. After ensuring that the extracellular domain ofCD147molecule can significantly upregulated the expression of MMP-2inhepatocellular carcinoma cells, we stimulated cells with different concentrationsof recombinant extracellular domain of CD147, we found that the optimizedconcentration of CD147molecule mediating MMP-2expression in HCC was10μg/ml.Part Ⅲ: The effect of cell membrane CD147in SMMC-7721on theregulation of MMP-2expression by soluble CD147.At first, we tested the expression level of CD147in different cell lines toconfirm the difference on CD147expression levels. Then, the expression levelof MMP-2was investigated after being stimulated by soluble CD147with thesame concentration. Our results demonstrated that the higher expression level ofCD147, the more changes in the expression level of MMP-2after beingstimulated by soluble CD147. It indicated that the regulation of soluble CD147on the expression of MMP-2is associated with its membrane CD147type.Take together, our results indicated that full lengthen soluble CD147wasexisted in SMMC-7721cell culture medium. We stimulated SMMC-7721cellswith either recombinant soluble CD147extracellular fragment or intracellularfragment and found that the expression level of MMP-2was only upregulated inSMMC-7721cells after being stimulated with soluble CD147extracellularportion and the expression level of membrane CD147played a role in the regulation of soluble CD147on the MMP-2expression.