TCM utilizes a multicomponent and multitarget synergistic system that accounts for the complexity of various herbal components acting on multiple targets and diseases. These ingredients with distinct effects and targets can act on various aspects of a disease via multiple systems, and they interact to produce synergistic effects [11, 12]. Network pharmacology can be used to predict the target profiles and pharmacological actions of herbal compounds. The present study used network-construction approaches to identify the bioactive compounds in ADI and their potential targets, and to determine the mechanisms underlying the effects of ADI in NSCLC.
Our topological analysis of the component drugs and target interaction network revealed that the active ingredients that may play important roles in ADI are quercetin, kaempferol, sitosterol, isorhamnetin, 7-O-methylisomucronulatol, formononetin, and cantharidin. Quercetin is a flavonoid compound that functions as an antioxidant, scavenging free radicals and lowering blood lipid and blood glucose levels [13, 14]. Quercetin inhibits the activity of NSCLC cells by regulating the mir-16/HOXA10 axis, and promotes the apoptosis of NSCLC cancer cells . Quercetin may inhibit the STAT3 signaling pathway, inhibit the migration and invasion of A549 cells, and induce the apoptosis of tumor cells .
Kaempferol exerts numerous pharmacological effects, including anti-oxidation, ant-ivirus, anti-bacterial, and anti-cancer effects. By inhibiting ERR beam, kaempferol reduces the invasion and migration of NSCLC A549 cells ,inhibits the proliferation of H446 cells in small-cell lung cancer, inhibits H446 cells in the S and G2/M phases of the cell cycle, and induces the apoptosis of H446 cells .
Cantharidin is the effective medicinal component of cantharides that exerts beneficial effects against malignant tumors such as liver cancer, esophageal cancer, lung cancer, and gastric cancer . Cantharidin inhibits the activity of caspase-3 and caspase-7 downstream of the apoptotic pathway via the expression of survivin, thereby inducing apoptosis .
Formononetin can induce the apoptosis of human colon and prostate cancer cells. The mechanism via which formononetin inhibits the proliferation of lung cancer A549 cells may be related to the induction of apoptosis and down-regulation of the expression level of bcl-2 .
Isorhamnetin and quercetin are both flavonoid compounds. Recent studies have found that isorhamnetin exhibits beneficial cardiovascular effects such as anti-myocardial hypoxia and ischemia, relieving angina pectoris, anti-arrhythmia effects, inhibiting antioxidant free radicals, and lowering serum cholesterol . The anti-cancer effect of isorhamnetin is associated with the induction of apoptosis, which may change the expression of apoptosis-related genes such as down-regulating the expression of bcl-2 and changing the bcl-2/Bax ratio by regulating members of the bcl-2 protein family . Isorhamnetin down-regulates the expression of bcl-2 gene and PCNA protein. Isorhamnetin also up-regulates the tumor suppressor genes P53, Bax, and caspase-3, and so it may mainly act by inhibiting the DNA synthesis of tumor cells. The up-regulation or down-regulation of apoptosis-related genes induces the apoptosis of cancer cells to inhibits their proliferation and growth .
VEGFA binds to its receptor-2 (VEGFAR-2) to promote the proliferation, growth, and survival of vascular endothelial cells. The expression of VEGFA is increased in malignant tumor cells, which is associated with the level of VEGFAR-2 being up-regulated to enhance tumor growth and proliferation . Wei et al. found that VEGFA promoted the growth and proliferation of NSCLC tumor cells and accelerated tumor progression . C-JUN is a major member of the AP-1 family of nuclear transcription factors. Phosphorylation and activation by P-JNK results in C-JUN forming homologous or heterodimers with transcription factors such as C-FOS, activating and initiating the expression of downstream target gene cyclin D1, regulating the cell cycle, and promoting cell proliferation .
Tumor metastasis is a complex process involving intracellular signal transduction. Tumor cells synthesize and secrete MMP to degrade the extracellular matrix and promote their own invasion and metastasis . MMP9 is an important member of the family of MMPs that is closely related to tumor invasion and metastasis, and its expression is up-regulated in various tumor tissues . FOXC2 may promote the invasion and migration of NSCLC cells by up-regulating MMP9. CASP1 regulates tumors in two ways : (1) by mediating the release of IL-1β, which plays a key regulatory role in the occurrence and development of tumors by regulating the development of myeloid cells in peripheral tissues and tumor microenvironment , and (2)by inhibiting tumor growth by activating the acquired immunity or apoptosis of tumor cells.CASP1 exists in cells without an active enzyme progenitor, and is activated by the macromolecule ASC dimer , which further catalyzes the proteolysis of caspase-7 and other acting substrates, leading to apoptosis .
The results obtained in the analysis of KEGG-pathway enrichment were mainly related to cancer pathways, hepatitis B, the relaxin signaling pathway, the TNF signaling pathway, the C-type lectin receptor signaling pathway, Th17 cell differentiation, the IL-17 signaling pathway, and human T-cell leukemia virus 1 infection. The IL-17 family includes a subset of cytokines consisting of IL-17A to IL-17AF, which play crucial roles in both acute and chronic inflammatory responses. The IL-17-family protein signal via their correspondent receptors to activate downstream pathways that include NF-kappa, MAPKs, and C/EBPs to induce the expression of antimicrobial peptides, cytokines, and chemokines. Human T-cell leukemia virus type 1 is a pathogenic retrovirus that is associated with adult T-cell leukemia/lymphoma. The pathogenesis is critically affected by the expression of the viral regulatory protein Tax, which is a transcriptional cofactor that interferes in several signaling pathways related to anti-apoptosis and cell proliferation.
TNF is a critical cytokine that can induce a wide range of intracellular signal pathways, including those related to apoptosis, cell survival, inflammation, and immunity. Th17 cells serve as a subset of CD4+ T cells involved in immune responses mediated by epithelial cells and neutrophils against extracellular microbes, and they are involved in the pathogenesis of autoimmune diseases. We found that these signaling pathways are closely related to NSCLC, and the active components in ADI can exert treatment effects against that cancer via these signaling pathways.
This study utilized network pharmacology to analyze the mechanisms underlying the effects of ADI in treating NSCLC. This approach has yielded important information for improving the understanding of compound–target–disease interactions, and also for providing ideas and acting as the basis for further studies. However, this study was subject to some limitations. The mechanism of action of ADI was only analyzed theoretically, and the predicted results might not be correct. Also, network information technology is not yet fully developed, and the analyzed databases are not completely up to date.
Notwithstanding the above limitations, this study applied bioinformatics and network pharmacology to explore the multicomponent and multitarget characteristics of ADI in treating cancer. We have identified that ADI involves 33 active ingredients that act against NSCLC, and some of their active anticancer effects have been confirmed in previous studies, such as for quercetin, kaempferol, sitosterol, isorhamnetin, 7-O-methylisomucronulatol, formononetin, and cantharidin. Our enrichment analysis revealed that the TNF signaling pathway, the C-type lectin receptor signaling pathway, Th17-cell differentiation, the IL-17 signaling pathway, and human T-cell leukemia virus 1 infection are important anti-NSCLC mechanisms of the active components in ADI.