PO-037 Role of MARCH8 in esophageal squamous cell carcinoma

Abstract

Introductionβ2-glycoprotein I (β2-GPI) is a human plasma protein which has been reported to inhibit human aorta endothelial cell migration in our previous study. Migration of endothelial cells has been found to be involved in tumorigenesis, however, whether β2-GPI regulates tumor cell migration or tumor growth is still unknown. In this study, we investigated the biological function and the structural characteristics of β2-GPI in suppression of melanoma cells.Material and methodsDifferent lengths of cDNA encoding β2-GPI gene has been constructed and cloned into the pFastBac vector using a Bac-to-Bac baculovirus expression system. This recombinant β2-GPI genes were transfected into insect Sf9 cells to generate recombinant β2-GPI peptides. Expression and purification of the recombinant proteins were performed to identify the function domain of β2-GPI in anti-melanoma cell migration. Cell migration was determined by wound healing and transwell migration assays. Cell proliferation was determined by cell counting assay. Effects of purified β2-GPI and recombinant β2-GPI domains on tumor growth in vivo were determined in the melanoma cell-implanted mice. The structural and functional relationships among specific peptide domains and regression of tumor growth were investigated using amino acid sequence alignment, solvent accessible surface area, and 3-D structure of human β2-GPI.Results and discussionsWe found for the first time that purified β2-GPI and several recombinant peptides of β2-GPI were able to suppress melanoma cell migration and proliferation. Furthermore, the purified β2-GPI and some specific recombinant domains of β2-GPI inhibited tumor growth in vivo. To highlight the structural and functional relationship between specific peptide motif and regression of melanoma growth, we compare the amino acid sequences among the DI to IV domains. The sequences of D1 contain more different amino acid residues compared to other β2-GPI domains. We thus investigate more structural characteristics of β2-GPI D1 peptide, which may shed light on its function in anti-melanoma growth.ConclusionThis study sought specific sites within β2-GPI functional domain which may interact with melanoma cell membrane and play essential roles in the suppression of melanoma growth.