Chinese medicine has a history of thousands of years, and herb medicines exert extensive biological and pharmacological effects through a variety of compounds and targets. Network pharmacology is an available tool to identify alternative targets for herbal medicines and to develop multi-target drugs. In this study, we analyzed the PPI of AR-CR on the effective targets of CG, and obtained multiple kernel targets including AKT1, TNF, JUN, MAPK3, MAPK8 and MAPK1. In order to clarify how the AR-CR worked through these targets, the GO enrichment analysis and the KEGG pathway enrichment analysis were further performed in this study. Through the GO enrichment analysis, we thought that the herb pair AR-CR was able to regulate the protein binding, enzyme binding, response to drug, response to estradiol, etc. The enrichment results of the KEGG signaling pathway showed that the main function of AR-CR might be related to the Pathways in cancer, TNF signaling pathway, Apoptosis, and VEGF signaling pathway, etc.
In the PPI network analysis, one of the key genes such as AKT1 is tightly related to gastrointestinal cancers [5]. The activation of AKT1 induces cell proliferation through the stimulation of cell cycle progression and inhibits the intrinsic apoptotic pathway [6]. The amount of AKT1 protein can stimulate the proliferation of neoplastic cells,and AKT1 was overexpressed in 8% of tumors and associated with a trend for a poor overall survival [6]. Rescue experiments demonstrated that decreased proliferation and increased apoptosis of gastric cancer cells induced by miRNA4903p overexpression were partially suppressed by AKT1 overexpression [7].
TNF is an important regulator of inflammation and immunity, including TNF - α and TNF - β. TNF - α is the main inflammatory cytokine, which maintains homeostasis by regulating inflammation, cell proliferation, differentiation, survival and apoptosis [8]. The increased expression of TNF-α in the sequential evolution of gastric cancer, the gastric precancerous conditions such as chronic gastritis, intestinal metaplasia, dysplasia and gastric adenocarcinoma patients showed the high expression of TNF-α [9]. Xu et al. reported that TNF-α was a major part in inflammatory, infectious and tumor processes, and is pivotal at the early stages of gastric cancer, and TNF-α rs361525 polymorphism is related to the risk of gastric cancer, especially for Asians [10]. In the development from CG to gastric cancer, TNF signaling pathway plays an important component in the inflammatory response and tumor [11].
Jun is also known as c-Jun, which played a key component in the tumorigenesis of gastric cancer. Miao et al. reported that KIAA1429 contributed to promoting gastric cancer by regulating c-Jun expression in a m6A independent manner [12]. Peng et al. reported that c‐Jun could promote the proliferation, metastasis, and invasion of gastric cancer cells in vitro and in vivo by accelerating the expression of FOXK1 at the transcriptional level [13].
MAPK is a group of serine/threonine protein kinases that can be activated by different extracellular stimuli, such as cytokines, neurotransmitters, hormones, cell stress and cell adhesion, which regulate cell growth, differentiation, stress adaptation to the environment, inflammatory response and other important cellular physiological and pathological processes. MAPK3, MAPK1 and MAPK8 are member of the MAPK family. The cell proliferation and invasion of gastric cancer cells were reported to be propelled by the activation of MAPK signaling pathway [14]. MAPK3 is also known as ERK1, is an important signal transduction molecule in the ERK/MAPK pathway [15]. The ERK/MAPK signal transduction pathway is widely expressed in various tissues and cells, and it can regulate various biological processes such as cell proliferation, cycle, apoptosis, migration, and invasion [16, 17]. Enhanced functional activity of MAPK3 contributed to the development and progression of gastric cancer [18–20]. Knockdown of MAPK1 expression in gastric cancer cell lines induced cell growth retardation, apoptosis, and suppressed cell migration as well as invasion [21]. Diao et al. [22] reported that lncRNA GAPLINC was increased and positively correlated with MAPK1 expression in gastric cancer tumor tissues, additionally, the enhancement of gastric cancer cell proliferation and cell cycle progression by lncRNA GAPLINC was dependent on MAPK1. MAPK1 is a direct target gene of miR-585 that promotes the proliferation and metastasis of gastric cancer [23].MAPK8, which is also known as JNK, is characterized as a pronounced marked protein, is an important cellular pathway triggered in response to DNA damage, and it was also proved to be associated with tumor progression, including cell survival, migration and autophagy [24]. Sun et al. [25] reported that MAPK8 could mediate S/G2 phase cycle arrest and apoptosis, and suppress AKT activation in gastric cancer cells, and dysregulated MAPK8 was observed in several cancers, such as glioblastoma, skin cancer, brain tumor and leukemia [26, 27].
Increased apoptosis is associated with the development of gastric carcinoma, and H. pylori infection induces apoptosis in gastric epithelial cells by stimulating the host’s inflammatory/immune responses [28]. Stimuli and inhibitors for apoptosis may act at targets on the cell membrane via Fas and TNF receptors either in the cytoplasm or in the nucleus [28]. The ethanol-induced apoptosis of gastric mucosa could be ascribed to increases in TNF-α level, Bax, and caspase-3 activity [29]. A feature of malignancies is an alteration of cell turnover leading to cell hyperproliferation and to deregulation of apoptosis [30]. With deepening researches, a sustained inflammatory reaction and abnormal apoptosis of gastric mucosa are confirmed as important causes in the pathogenesis of chronic atrophic gastritis, which have drawn growing attention [31, 32]. An impaired balance between proliferation and apoptosis was detected in gastric cancer and in atrophic gastritis or intestinal metaplasia in gastric mucosa adjacent to cancer [33].
VEGF contribute to stimulate the growth and differentiation of vascular endothelial cells, is an essential factor in cancer development and progression, its receptors include VEGFR1 and VEGFR2. VEGF could exhibit different levels of expressions in precancerous lesions and gastric cancer, and it is involved in the occurrence and development of gastric cancer [34]. Canonical VEGF signaling through VEGFR1/R2 regulates the activities of several kinases and ultimately guides cell proliferation, migration, survival, and vascular permeability during vasculogenesis and angiogenesis [35]. Inhibiting the VEGF/VEGFR pathway could cause a rapid and sustained antiangiogenic/antitumor response [36].