Identification of human serum protein targets of Qianggu Decoction () in primary type I osteoporosis based on tandem mass tag labeling and liquid chromatography-tandem mass spectrometry technology

Objective: To investigate the serum protein targets of Qianggu Decoction (, QGD) on treating osteoporosis by the proteomics analysis using tandem mass tag (TMT) and liquid chromatographytandem mass spectrometry (LC-MS/MS).

Methods: Twenty serum protein samples were recruited (10 patients with primary type I osteoporosis before and after QGD treatment) and the high abundance ratios protein was removed, two serum samples were extracted and labeled with TMT reagent. Then, mass spectrometric detection, identification of differentially expressed proteins and bioinformatics analysis of differentially expressed proteins were carried out.

Results: A total of 60 proteins were identified, within a 99% confidence interval, to be differentially regulated of which, 34 proteins were up-regulated and 26 proteins were down-regulated. Differentially expressed proteins analyzed by Gene Ontology (GO) annotation mainly get involved in 12 different biological processes, 7 types of cellular components, and 6 kinds of molecular functions. Angiotensinogen (AGT), stromelysin-1 (MMP3), heparanase (HPSE) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) were screened as candidate protein targets of QGD treatment, which were related to metabolic mechanism of bone remodeling and/or bone collagen of osteoporosis. By the utilization of the protein-protein interaction network analysis tool named STRING10.0, it showed that AGT, MMP3, HPSE and GAPDH were located in the key node of the protein-protein interactions network. Furthermore, AGT, MMP3, HPSE and GAPDH were found to be directly related to BMP, MAPK, Wnt, SMAD and tumor necrosis factor ligand superfamily member 11 (TNFSF11) families.

Conclusions: The proteomics analysis by using TMT combined with LC-MS/MS was a feasible method for screening the potential therapeutic targets associated with QGD treatment. It suggests that AGT, MMP3, HPSE and GAPDH may be candidate protein targets of QGD treatment which can be used as therapeutic effect monitor and early diagnosis of primary type I osteoporosis.