Identification Of TIMP1 Cell Membrane Receptor And Analysis Of Its Biological Fuction

Tissue inhibitor of metalloproteinases 1(TIMP1) is a widely expressed and secreted protein that regulates the enzyme activity of matrix metalloproteinases(MMPs) and plays a role in cell motility, proliferation and apoptosis. Although the underlying pathway of TIMP1-induced apoptosis inhibition through some membrane proteins in normal cells has been partially elucidated, its pathogenic mechanism in cancer cells is not completely understood. In this study, we show that CD82, a member of the transmembrane 4 superfamily, directly interacts with TIMP1 by bioinformatics analyses and in vitro chemical crosslinking. It may be the intricate TIMP1 receptor or one component of the receptor. TIMP1-CD82 colocalization on the cancer cell surface was confirmed in vitro and in vivo. Moreover, a cell co-culture system was used to mimic cancer cell microenvironment in vivo. We observed that TIMP1 was internalized in the human pancreatic carcinoma PANC-1 cell line, breast carcinoma MCF-7 cell line and colorectal adenocarcinoma LoVo cell line, but not in the human embryonic renal fibroblasts. Silencing the expression of membrane CD82 entirely eliminated this phenomenon. In vitro, series of wound closure assay and label tracing experiment indicated that TIMP1, but not TIMP2, affected Akt signaling pathway, decreased actin cytoskeleton remodeling and specifically inhibited migration of PANC-1 cells without affecting primary cell growth, probably, in a MMP-dependent way. CD82 knockdown efficiently blocked these effects. However, CD82 transcription level was not influenced by TIMP1 overexpression in several cell lines. In conclusion, this is the first study to show the interaction between free TIMP1 and cancer cell surface CD82. CD82 directly interacts with TIMP1, facilitating its intracellular trafficking, turnover, and significantly contributes to the anticarcinogenic effect of TIMP1 in pancreatic carcinoma cells. Our results suggest that recognition of the TIMP1/CD82 axis may help further our understanding of the cancer development process.