Effects Of Bone Sialoprotein And Its Glycosylation On The Invasion Of Breast Cancer

Objective: To investigate the effects of BSP and its glycosylation on the invasion of breast cancer cells as well as the possible underlying mechanisms.Methods:1.The effects of BSP on the proliferation and invasion of MCF-7 cells and MDA-MB-231 cells were detected by CCK-8 and transwell assay respectively.Different glycosidases were used to remove the N-glycans,O-glycans or terminal sialic acids of BSP.The effects of different deglycosylated BSPs on the proliferation and invasion of MCF-7 cells and MDA-MB-231 cells were detected by CCK-8 and transwell assay respectively.2.Western Blot was used to detect the effects of BSP and different deglycosylated BSPs on the expression of invasion-related protein factorsin MCF-7 and MDA-MB-231 cells.3.The effects of 1?,25(OH)2D3 on proliferation and invasion of MCF-7 cells and MDA-MB-231 were detected by CCK-8 and transwell assay respectively.Co-immunoprecipitation was then used to determine whether BSP competes with1?,25(OH)2D3 for VDR binding and therefore affects the invasion of breast cancer cells.Results:1.BSP promotes the proliferation and invasion of MCF-7 cells and MDA-MB-231 cells.Different deglycosylated BSPs promote the proliferation of MCF-7 cells,but their effects on the invasion of MCF-7 cells are not significant.Different deglycosylated BSPs have different effects on the proliferation and invasion of MDA-MB-231 cells,BSP with N-glycansremoved has no significant effects on theproliferation of MDA-MB-231 cells and BSP withsialic acidsremoved exhibit little effect on the invasion of MDA-MB-231 cells.2.BSP increase the expression of TGF-?,Smad2/3,MMP2,and VEGF at protein level in MCF-7 and MDA-MB-231 cells,however the effect of BSP with sialic acidsremoved on these proteins are not significant.The increase of MMP2 at protein level in MCF-7 cells is mainly promoted by BSP with O-glycansremoved,which in MDA-MB-231 cells is mainly promoted by BSP with N-glycansremoved.3.The proliferation and invasion of MCF-7 and MDA-MB-231 cells were inhibited after 100 n Mof 1?,25(OH)2D3 was added.Co-immunoprecipitation detected that BSP associated with VDR,which was inhibited by 1?,25(OH)2D3.Conclusion:BSP promote the proliferation and invasion of MCF-7 and MDA-MB-231 cells.1?,25(OH)2D3 inhibite the proliferation and invasion of MCF-7 and MDA-MB-231 cells.BSP may affect the invasion of breast cancer cells through TGF-? signaling pathway or competition with 1?,25(OH)2D3 to bind VDR.