Identification of an active site of EMMPRIN for the augmentation of matrix metalloproteinase-1 and -3 expression in a co-culture of human uterine cervical carcinoma cells and fibroblasts

Abstract

Objective Extracellular matrix metalloproteinase inducer (EMMPRIN) is highly expressed on malignant tumor cell surface and accelerates tumor invasion. We previously reported that human uterine cervical carcinoma SKG-II cells exhibit the progression of in-vitro invasiveness by utilizing the enhanced production of matrix metalloproteinase (MMP) in human uterine cervical fibroblasts (HUCF) under an in-vitro co-culture model (Sato T et al., Gynecol Oncol 2004; 92:47–56). The aim of this study was to clarify the active site of EMMPRIN in the augmentation of MMP production in the co-culture of SKG-II cells and HUCF. Methods Western and Northern blot analyses were used to examine EMMPRIN and MMP expression in a co-culture of SKG-II cells or EMMPRIN-transfected COS-7 cells and HUCF. A systematic peptide screening method using nine synthetic EMMPRIN peptides was used to identify active site(s) of EMMPRIN for MMP induction. Results SKG-II cells constitutively expressed 53-kDa EMMPRIN on the cell surface and EMMPRIN production was enhanced under the co-culture. The concomitant augmentation of proMMP-3 production was diminished by adding an EMMPRIN antibody. EMMPRIN-transfected COS-7 cells stimulated HUCF to predominantly augment proMMP-1 and -3 expressions. A systematic peptide screening method revealed that 42SLNDSATEVTGHRWLK 57 in the first loop domain of EMMPRIN participated in the augmentation of proMMP-1 production. Conclusions These results provide a novel mechanism of malignancy of uterine cervical carcinoma, in that the augmentation of EMMPRIN expression by tumor–stromal cell interaction progresses tumor invasion along with the increase of MMP expression via an active site of EMMPRIN, 42SLNDSATEVTGHRWLK 57.