Triptolide is a Promising Therapeutic Approach in Treating Thyroid Cancer Based on in silico and in vitro Experiment

Abstract

Introduction

Thyroid cancer is a familiar kind of cancer. Natural products are promising therapeutic approaches in treating thyroid cancer. Triptolide is a diterpenoid epoxide extracted from Tripterygium wilfordii. The mechanism of triptolide in the treatment of thyroid cancer has not been investigated clearly.

Methods

We evaluated triptolide targets and thyroid cancer targets with related databases. The protein–protein interaction (PPI) networks of the triptolide targets and thyroid cancer targets were constructed with Cytoscape software. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses of the core PPI network were obtained. Molecular docking analysis was used to evaluated the binding of triptolide with core targets. Furthermore, apoptosis assays, real-time polymerase chain reaction (RT-PCR) and Western blotting were used to evaluate the anticancer functions of triptolide.

Results

Triptolide had 34 targets, and thyroid cancer had 210 targets. The core PPI network of merged PPI networks had 164 nodes and 4513 edges. GO and KEGG enrichment analyses showed that triptolide were related to the cell cycle, apoptosis, and inflammatory signaling pathways. Molecular docking analysis showed that triptolide directly reacted with four core targets: cyclin-dependent kinase inhibitor 1A (CDKN1A), c-JUN, RELA, and tumor protein p53 (TP53). CB-Dock analysis indicated that triptolide could stably bind to core targets. Triptolide inhibited the growth but induced apoptosis of thyroid cancer cells. Triptolide increased the mRNA expression of CDKN1A and TP53 but reduced the mRNA expression of c-JUN and RELA, as shown by RT-PCR. Triptolide increased the protein levels of CDKN1A and phospho-p53 but reduced those of phospho-c-JUN and phospho-NF-κB p65, as shown by Western blotting.

Discussion

We considered that triptolide could treat thyroid cancer by inhibiting cell proliferation, inducing apoptosis and inhibiting inflammatory pathways such as the NF-κB and MAPK signaling pathways. CDKN1A, c-JUN, RELA, and TP53 were involved in the antithyroid cancer mechanism of triptolide.

Keywords:

• triptolide
• thyroid cancer
• molecular docking
• apoptosis
• inflammation

Acknowledgments

This work was supported by the National Natural Science Foundation of China [grant numbers 81500689].

Abbreviations

AKAP9, A-Kinase Anchoring Protein 9; BC, betweenness centrality; Bcl-2, B-cell lymphoma 2; Bcl-Xl, B-cell lymphoma-extra large; BIND, Biomolecular Interaction Network Database; BioGRID, Biological General Repository for Interaction Datasets; BP, biological process; CC, closeness centrality; CC, cellular component; CCKBR, Cholecystokinin B Receptor; CKDN1A, cyclin-dependent kinase inhibitor 1A; CDKN1B, Cyclin Dependent Kinase Inhibitor 1B; CXCL8, C-X-C Motif Chemokine Ligand 8; DC, degree centrality; DIP, Database for Interacting Proteins; EC, eigenvector centrality; EDTA, Ethylenediaminetetraacetic acid; FBS, fetal bovine serum; FITC, Fluorescein isothiocyanate; GAD, Genetic Association Database; GAPDH, glyceraldehyde 3-phosphate dehydrogenase; GO, Gene ontology; HMGCR, 3-Hydroxy-3-Methylglutaryl-CoA Reductase; HPRD, Human Protein Reference Database; IBD, inflammatory bowel disease; IL-1β, interleukin 1 beta; IL-6, interleukin 6; IONM, intraoperative neuromonitoring; JAK1, Janus Kinase 1; KEGG, Kyoto Encyclopedia of Genes and Genomes; LAC, local average connectivity centrality; MAPK, Mitogen-Activated Protein Kinase; MF, molecular function; MINT, Molecular INTeraction Database; NC, neighbourhood centrality; OMIM, Online Mendelian Inheritance in Man; PBST, phosphate buffered saline with Tween 20; PharmGKB, Pharmacogenomics Knowledge Base; PI, propidium iodide; PMSF, phenylmethylsulfonyl fluoride; PPI, protein-protein interaction; RA, rheumatoid arthritis; RT-PCR, real-time polymerase chain reaction; TCMSP, traditional Chinese medicine systems pharmacology; TNF-α, tumor necrosis factor alpha; TP53, tumor protein p53; TTD, Therapeutic Target Database.

Disclosure

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.