Network pharmacology and experimental validation to study the potential mechanism of Tongguanteng injection in regulating apoptosis in osteosarcoma
Authors: Wei Lanyi , Meng Jingjing , Xiang Danfeng , Yang Quanjun , Zhou Yangyun , Xu Lingyan , Wang Mengyue , Chen Junjun , Han Yonglong 
Published: January 2024

Abstract
Objective
The main objectives of this study were to identify the active components of Tongguanteng injection (TGT) and investigate the preclinical efficacy and mechanism of TGT on osteosarcoma using a combination of network pharmacology and experimental validation.

Methods
To identify the active constituents and targets of TGT against osteosarcoma using network pharmacology, we constructed a network consisting of an 'active ingredient-disease-target-pathway' and a protein–protein interaction (PPI) network. The target organ network was utilized to investigate the distribution of core targets in tissues. Afterwards, the core targets underwent Gene ontology (GO) functional enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. The binding energy between receptors and ligands was compared using molecular docking. In addition, SwissADME was employed to forecast the pharmacokinetic characteristics of the substances. Finally, real-time polymerase chain reaction (RT-PCR), cell proliferation assay, morphological analysis, apoptosis assay, mitochondrial membrane potential (MMP) detection, and Western blotting were utilized to confirm the potential mechanisms of TGT treatment in osteosarcoma cell lines 143B and SAOS2.

Results
A total of 54 chemical constituents of TGT and 71 targets associated with osteosarcoma were acquired. Through the molecular docking technology, Tenacigenin B, Marsdekoiside, Taraxasterol, Tenacissoside G, Tenacissoside L, and Tenacissoside J were identified as the primary active components of TGT among the various compounds. Analysis of target organs suggests that TGT may play an anti-osteosarcoma role through immune regulation. The GO and KEGG enrichment analysis revealed that TGT could trigger osteosarcoma cell apoptosis by inhibiting the HIF-1 signalling pathway and modulating PD-1 expression and the PD-1 checkpoint pathway in cancer. SwissADME database predicted that Tenacigenin B and Taraxasterol had the best drug-likeness. In vitro studies also demonstrated that TGT suppressed the activity and induced alterations in the morphology of osteosarcoma cells. It decreased MMP levels, triggered apoptosis by increasing Bax expression and Caspase-3 activity, and decreased Bcl-2 expression, thereby exerting an anti-osteosarcoma effect. In the meantime, RT-PCR tests demonstrated that TGT could control immune response against tumors and hinder the proliferation and spread of cancerous cells by impacting the levels of critical factors, including JUN, HSP90AA1, HDAC1, and CDK1.

Conclusion
The study accurately anticipated the active components, targets, and pathways of TGT in the management of osteosarcoma. The molecular mechanism of TGT-induced apoptosis in osteosarcoma cells was demonstrated by in vitro experiments. These results provide theoretical and technical support for TGT as a clinical adjuvant drug for osteosarcoma.