Currently, tumors have ended up one of the most serious diseases endangering human wellbeing. It is evaluated that by 2019, the number of tumor-related deaths will surpass 20 million around the world. The frequency of tumors in China is additionally on the rise year by year[26]. Chinese traditional medicine plays an imperative role in the prevention and treatment of tumors, and its role and mechanism in enhancing the immune function of the body, preventing the multidrug resistance of tumor cells, restraining the division and expansion of tumor cells, and accelerating the apoptosis of tumor cells are gradually revealed. The foundation for its effective application in antitumor has been laid[36]. Be that as it may, the composition of Chinese traditional medications is complex and their active ingredients are still unclear in pharmacology and clinical practice. The isolation of the monomers among them is time-consuming and costly, and the specific target genes or proteins for drug action have not been fully identified. In the past decade, with the fast improvement of high-throughput innovations and bioinformatics, the research of network pharmacology in disease treatment has attracted attention. Based on computer simulation technology, it provides an effective method for component screening and prediction of drug targets, which is a feasible solution to improve the correct rate of drug target prediction[18].
COE ( Celastrus orbiculatus Thunb extract) is an ethyl acetate extract of Celastrus orbiculatus Thunb, which is considered to be a very promising antitumor drug. Our group has continuously and thoroughly investigated the antitumor pharmacology of COE and elucidated its antitumor mechanism, the important extraction prepare and utilize have gotten Chinese national invention patent Past considers by our group have appeared that Triptonodiol, a monomer in COE, has antitumor activity. In this study, we further examine the mechanism of activity of Triptonodiol in lung cancer, and eighty-eight key targets were acquired. In addition, we used PPI to explore data mining and network analysis. We found 10 core targets, which are exceedingly connected with tumor resistance and proliferation.
Drug resistance is a multifactorial process also mediated by a cellular stress response to the tumor microenvironment [33]. Heat shock proteins (HSPs) are highly conserved molecular chaperone proteins that play an important role in cell survival. In stress conditions, heat shock proteins mediate tumor drug resistance through regulation of autophagy[2; 3]. HSP90AA1 is one of the most important heat shock proteins and is considered as a potential molecular target for tumor therapy [28]. In growing cells, high mTORC1 activity promotes biomolecule synthesis while inhibiting autophagy. mTORC1 inhibits autophagy induction by phosphorylation-dependent inhibition of ULK1/2 and VPS34 complexes and strictly regulates autophagy by blocking the overall expression of lysosomal and autophagic genes through TFEB phosphorylation[15]. AKT1/MTOR inhibition of autophagy promotes cell growth by inhibiting catabolism and accelerates tumor growth by promoting the warburg effect. mTORC1 prevents ULK1 activation by AMPK, a key activator of autophagy, by phosphorylating ULK1, which is involved in angiogenesis and EMT (Epithelial-Mesenchymal Transition) processes through autophagy regulation and promotes tumor metastasis. AKT is able to increase LC3-II levels and autophagic flux through the reduction of autophosphorylation [5; 35]. Not only that, AKT1 is also able to regulate cell proliferation through PIK3CA and GSK3B, by regulating cyclin D1 protein hydrolysis and subcellular localization[6]. GSK-3 is display in all eukaryotes and could be a broadly expressed and exceedingly conserved serine/threonine protein kinase that can be inactivated by p70S6k through serine 9/21 phosphorylation[27; 29; 30]. EMT can be positively regulated by the Wnt/β-catenin pathway[8], and GSK-3 plays an imperative administrative part in this process. Active GSK-3β can prevent transcription of β-catenin target genes by stimulating the degradation of β-catenin protein and promoting the destruction of nuclear phosphorylated β-catenin[13; 32]. P53, a potent tumor suppressor, exerts antiproliferative effects when faced with stress, including growth arrest and apoptosis[24]. In this study, MDM2 was also a potential target that scored highly, an oncoprotein that inhibit p53[21]. MDM2 promotes proliferation by binding to P53 and blocking its transcriptional activation domain[9]. On the other hand, there is an autoregulatory feedback loop between p53 and MDM2. At the same time, MDM2 can promote the degradation of P53 By binding to p53, even if P53 is in a steady state[9].
At the same time, we carried out KEGG enrichment analysis on the predicted target. The calculated results of KEGG enrichment are in high agreement with those of previous analysis. Triptonodiol is highly correlated with tumor signaling, especially ERBB and PI3K/AKT signaling. ERBB receptors were linked to human cancer pathogenesis approximately thirty years ago. The transmembrane receptor tyrosine kinases (RTKs) of the ERBB family include ERBB1, HER2, ERBB3, ERBB2 and HER4 [1]. ERBB family members play an important role in the occurrence and maintenance of various solid tumors, especially HER2 amplified breast cancer and EGFR mutated lung cancer. This led to the development and widespread implementation of specific ERBB inhibitors as cancer therapies. At the same time, particularly in lung cancer, the mutations of ERBB4 have been identified[22]. The mutation in the gatekeeper residue of EGFR, T790M is the most common mechanism of acquired resistance to EGFR inhibitors in the EGFR mutant lung cancer. At least 50% of biopsies from patients with acquired drug resistance carry the T790M mutation of EGFR[16; 20]. It is reported that, S492R mutation occurred in EGFR extracellular domain, which can interfere with the binding of cetuximab[17]. In addition to the immune effect of ERBB antibody, most of the activities of many similar drugs are due to the inhibition of downstream signal transduction, especially PI3K/AKT and MEK/ERK[1]. Therefore, although the targeted receptor is completely inhibited, at least one of these key downstream pathways is still maintained, so many cancers are resistant to ERBB inhibitors. This type of drug resistance, also known as "bypass track" resistance, is usually used to describe the drug resistance caused by maintaining these key downstream signal pathways when RTK is fully inhibited[19]. Therefore, the calculation results of Triptonodiol by network pharmacology model have excellent application prospect. Because our results show that Triptonodiol can regulate ERBB signal pathway and PI3K/AKT at the same time, theoretically, it can prevent the occurrence of drug resistance while treating cancer.
In conclusion, we provides a preliminary exploration of the dominant targets and effective pathways of Triptonodiol with the help of network pharmacology and laboratory validation of the protein molecules, confirming the anti-tumor pharmacological effects of Triptonodiol. With the help of network pharmacology, possible targets in Triptonodiol can be further explored, which may become the basis for the development of novel drugs, but more trials are still needed. Meanwhile, this study also further confirmed the antitumor effect of Triptonodiol and further promoted the development of drugs related to the Chinese medicine Celastrus orbiculatus Thunb.