Regulation of matrix metalloproteinase production and tumor cell invasion by four monoclonal antibodies against different epitopes of HAb18G/CD147 extracellular domain

HAb18G/CD147, a membrane spanning molecule and highly expressed in hepatocellular carcinoma (HCC) cells, was shown to stimulate the production of matrix metalloproteinases (MMPs) in the interaction of tumor cells and fibroblasts. Studies on the EMMPRIN/CD147 showed that CD147 extracellular domain is involved in the induction of MMPs. To study the biological molecular function of HAb18G/CD147 extracellular domain (HAb18G/CD147-ED) on production of MMPs following mediated tumor cell invasion, we isolated four novel monoclonal antibodies (MAbs)-1B3, 3B3, HAb18Gedomab1, and HAb18Gedomab2-against HAb18G/CD147-ED by immunization of BALB/c mice with purified HAb18G/CD147-ED fragments, which were efficiently expressed in Escherichia coli. Gelatin zymography and Boyden chamber assays were used to identify the production of MMPs in the co-cultured human fibroblast and HCC cells, and to quantify the migrated cells in the presence of the generated MAbs. The results showed that two MAbs (1B3 and 3B3) stimulated the secretion of MMP-2 and enhanced the HCC cell invasion, whereas the other two MAbs (HAb18Gedomab1 and HAb18Gedomab2) had reverse functions. FCM additive assay showed that four MAbs recognized different epitopes of HAb18G/CD147-ED. Taken together, the results suggest that various regions of HAb18G/CD147-ED participated in the regulation of MMP secretion.