TCM is an important part of the world health-care system [26]. It has a unique diagnosis and treatment system - "syndrome differentiation and treatment", which can diagnose and treat diseases from a macroscopic point of view, especially those difficult lesions with unknown aetiology and molecular mechanisms. Therefore, it is widely used in the prevention and treatment of a series of refractory diseases, including inhibition of tumour proliferation, induction of apoptosis and prevention of complications [27]. The mechanism of GPL is unknown, and there is a lack of effective methods to reverse gastric mucosal lesions, making the treatment of GPL challenging [28]. It is worth mentioning that Chinese medicine has achieved good efficacy in the treatment of GPL [29]. Coptidis Rhizoma is a widely used traditional Chinese medicine, which has been clinically used to treat gastrointestinal diseases and diabetes in the long history of TCM [30]. It is also the mainstay of many Chinese herbal compounds for the treatment of GPL, such as Huazhuojiedu decoction, Qinhuayin, and Weixibaonizhuan pills [31–33]. In vitro experiments have demonstrated that the main extracts of Coptidis Rhizoma, such as berberine and quercetin, have antitumor activities, such as inhibiting angiogenesis and inducing apoptosis [34–36]. However, its specific mechanism of action has not been fully elucidated. Therefore, we used network pharmacology and molecular docking methods to explore the potential molecular mechanisms of active compounds of Coptidis Rhizoma systematically and comprehensively in the treatment of GPL.
In our study, 11 active ingredients and 146 corresponding targets of Coptidis Rhizoma were first obtained from TCMSP database mining. In addition, 2108 targets of GPL were obtained from the GeneCards database and OMIM database. Comparing the drug target set and GPL disease target set, 95 potential targets of Coptidis Rhizoma were finally obtained. The active components of Coptidis Rhizoma mainly include alkaloids and flavonoids, all of which have good pharmacokinetic properties. According to the network diagram analysis of "component-target-pathway", alkaloids and flavonoids of Coptidis Rhizoma are the main active components of anti-tumour properties. This is consistent with modern medical confirmation that these alkaloids and flavonoids can inhibit PI3K/AKT signalling pathway and tyrosine kinase, thereby inducing apoptosis and inhibiting tumour proliferation [37–40].
The top five potential targets were AKT1, TP53, VEGFA, MYC and JUN. AKT1 is a member of the serine-threonine protein kinase family that regulates many cellular processes, including metabolism, proliferation, cell survival, growth, and angiogenesis [41]. AKT1 is a key regulator of cell proliferation [42] and drives cancer progression by transducing extracellular signals to the cytoplasm and nucleus through phosphorylation [43]. TP53 gene is a cell cycle-related gene, which plays an important role in cell proliferation and apoptosis by regulating cell cycle-related protein synthesis. Mutation or deletion of TP53 leads to cell cycle disturbance and apoptosis inhibition [44]. TP53 mutations are often present in premalignant lesions and may precede morphologic changes from adenomas to carcinomas [45–46]. VEGFA is a key pro-angiogenic ligand, and highly expressed VEGFA often stimulates angiogenesis and growth and is involved in tumour angiogenesis and metastasis [47–48]. MYC is a well-established oncogene involved in cell cycle progression, apoptosis, and cell transformation [49]. Important interactions exist between MYC and TP53 in many different cancers [50]. MYC amplification and TP53 mutations have synergistic effects in promoting histological grading phenotypes from low-grade tumours to high-grade tumours [51]. Activation of JUN and Fos phosphorylation leads to the formation of AP-1 complexes that activate the transcription of target genes and regulate angiogenesis-related cell proliferation, differentiation, survival, and migration [52]. In conclusion, mutations such as AKT1, TP53, VEGFA, MYC, and JUN are likely to have been present in precancerous gastric lesions, showing an imbalance between cell proliferation and apoptosis. The active components of Coptidis Rhizoma may regulate malignant progression, such as cell proliferation and apoptosis, angiogenesis and growth, by binding to the above-related receptors.
GO enrichment analysis showed that the mechanism of Coptidis Rhizoma acting on GPL involved multiple biological processes and molecular functions, of which the most relevant biological processes were gene expression regulation and apoptosis regulation, and the most relevant molecular functions were enzyme binding, transcription factor activity, sequence-specific DNA binding, and protein binding (enzyme binding, transcription factor binding activity, sequence-specific DNA binding, protein binding). From KEGG signalling pathway analysis, GPL are most closely related to two signalling pathways, the cancer pathway and the AGE-RAGE signalling pathway in diabetic complications. It is easy to understand that abnormal cancer signalling pathways underlie the development of GPL. Diabetic complications AGE-RAGE signalling pathway is associated with a series of complications of diabetes, such as retinopathy, neuropathy, cardiovascular lesions, and so on [53–56], which need not be repeated here. AGE-RAGE signal axis was also strongly correlated with GPL. It has been shown that AGE-RAGE intracellular signal transduction usually involves PI3K/Akt signalling pathway and MAPK/ERK pathway and plays a key role in regulating cell proliferation and cell differentiation [57–58]. At the same time, the AGE-RAGE signalling axis is also involved in VEGF-mediated angiogenesis, and cellular experiments have confirmed that RAGE receptors are positively associated with increased vascular density and cancer progression [59–60]. This also demonstrates from the side that the occurrence of tumours has an important link with diabetes [61].
As with tumour development, precancerous lesions are a complex disease process that may involve the dysregulation of multiple oncogenic signalling pathways (pathways in cancer). Twelve targets (EGF, EGFR, ERBB2, AKT1, FOS, IL1B, JUN, MYC, TNF, TP53, VEGFA, CASP3) of Coptidis Rhizoma against GPL were distributed on the MAPK signalling pathway (Fig. 7). There are nine targets (EGF, EGFR, ERBB2, AKT1, IL6, MYC, CCND1, TP53, VEGFA) of Coptidis Rhizoma against GPL involving the PI3K/AKT signalling pathway (Fig. 8). EGFR is located on the cell membrane and is an upstream part of the MAPK signalling pathway and the PI3K/AKT signalling pathway. Epidermal growth factor receptor (EGFR) is a cell surface receptor tyrosine kinases (RTK) with intrinsic protein tyrosine kinase activity [62–63]. EGFR is auto phosphorylated by tyrosine kinases when growth factors bind to EGFR [64]. Both MAPK pathway and PI3K/AKT pathway are involved in EGFR downstream signal transduction [65], participate in gastric mucosal repair, regulate mucosal cell growth and development, repair damaged mucosa, and are closely related to gastrointestinal epithelial cell differentiation, proliferation and maturation [66–67]. Overexpression of EGFR leads to excessive cell differentiation, and normal epithelial cells undergo dysplasia and further develop. Therefore, we speculated that the active ingredients of Coptidis Rhizoma act on EGFR receptors on the cell membrane, inhibit the MAPK signalling pathway and PI3K/AKT pathway, and prevent atrophy and dysplasia in excessive differentiation of gastric mucosal cells. Molecular docking results showed that there was a good binding ability between the active components of Coptidis Rhizoma and each target, in which the key target EGFR had a strong binding ability with the key active components CR10, CR9, CR1, CR2, and CR3, and AKT1, MYC, and TP53 also had a good binding ability with each key active component.