Proteomic Analysis Of Bone Sialoprotein–Interacting Proteins In Breast Cancer

Cancer is the second leading cause of human death globally,and is responsible for an estimated 9.6 million deaths in 2018.Globally,about 1 in 6 deaths is due to cancer.In the most countries,the incidence and mortality of breast cancer rank first among female cancers.The economic cost of cancer is estimated at $1.16 trillion in2010.Bone sialoprotein(BSP),an important extracellular matrix noncollagenous glycosylated phosphoprotein of bone,is overexpressed in many malignant tissues,including breast cancer,prostate cancer,lung cancer,thyroid cancer and melanoma.It is involved in angiogenesis and tumor cell adhesion,proliferation,migration,invasion,escaping host defense and metastasis.However,the precise molecular mechanisms remain unclear.Objective:To identify the BSP interacting proteins in breast cancer and provide important evidence for the prevention and treatment of BSP-related cancers.Methods:BSP was purified by sequential chromatography on columns of DE-52,TSK gel G3000 SW,hydroxyapatite and C4 reverse HPLC.It was covalently bound to Dynabeads Dynabeads M-450 Tosylactivated magnetic beads,then incubated with human breast cancer cell line MDA-MB-231(MDA)cells.The BSP-interacting proteins were immobilized,purified and analyzed by LC-MS/MS followed by STRING,Gene Ontology and Pathway analyses.Results:A single protein was purified from bovine bone and identified as BSP by LC-MS/MS.Proteomic analyses showed 511 BSP-interacting proteins in the MDA cells.The first 50 proteins with high Mascot scores of peptide fragments were processed and analyzed by STRING,forming a molecular network consisting of three small networks.The glyceraldehyde-3-phosphate dehydrogenase acted as a "bridge" among the three small networks.The Gene Ontology and Pathway analyses revealed that among the 50 proteins i)the majority were components of cells or organelles;ii)the majority had binding or structural molecular activity;iii)the majority were involved in cellular and metabolic processes;iv)although integrins were not detected,the pathways including integrin signaling were determined.It is it is noteworthy that BSP interacted with a2-HS glycoprotein,another extracellular matrix protein.Conclusions:This study showed the 511 BSP-interacting proteins in MDA cells.The first50 proteins with high Mascot scores of peptide fragments are processed and analyzed by STRING,forming a molecular network consisting of three small networks.The glyceraldehyde-3-phosphate dehydrogenase acted as a "bridge" among the three small networks.Among the 50 proteins i)the majority were components of cells or organelles;ii)the majority had binding or structural molecular activity;iii)the majority were involved in cellular and metabolic processes;iv)although integrins were not detected,the pathways including integrin signaling were determined.BSP interacted with α2-HS glycoprotein.