In this research, we analyzed the potential therapeutic value of mangiferin for LUAD. Cell lines A549, H2030 and H1299 were processed with mangiferin, and bioinformatic analysis was employed, which helped us to construct the top 200 lncRNA-mRNA pairs network. We also obtained 12 lncRNAs and 18 mRNAs from differential expression calculations, degrees of connection in the lncRNA-mRNA network and PPI network, which were considered to be underlying targets of mangiferin. Additionally, mangiferin was mostly thought to affect the PI3K-Akt signaling pathway in LUAD. Furthermore, lncRNA-mRNA pairs that contained the genes ARHGAP29, BRIX1, CD109, CDK1, CTNNAL1, DAB2IP, DDIT4L, GPR162, ICAM5, KCNAB3 and MMP7 were determined to be meaningful lncRNA-mRNA pairs affected by mangiferin in LUAD. Generally, our study helped to elucidate the potential therapeutic value of mangiferin for LUAD.
In recent years, traditional Chinese medicine (TCM) or products have exhibited the effects of tumor prevention and treatment. Studies employing molecular biology and biochemical pharmacology to investigate the underlying mechanism governing these effects have opened new approaches for clinical antineoplastic drug development. In our study, mangiferin is a widely sourced treatment option that has shown therapeutic value in such cancer types as liver cancer, ovarian cancer, gastric cancer, and lung cancer[15, 17, 37, 38], while potential targets, such as NFκB, PPARү, MMP-7, MMP-9 and EMT, were predicted. Similarly, we adopted the experimental method of a self-control study treated with mangiferin to explore the medicinal effect of mangiferin in LUAD cell lines.
Regarding how to evaluate the potential value of mangiferin for treating cancer, the trend of antitumor chemotherapy prefers targeted medicine development, which provides a useful reference for further research on this subject. A large amount of research has been devoted to the molecular mechanism of tumorigenesis and development, which encourage and contribute to the development of molecularly targeted treatment. Given several examples, Wang et al. have considered W934, a novel PI3K/Akt pathway inhibitor, to be a potential therapeutic drug candidate to treat the non-small-cell lung cancer (NSCLC). Research from Yang et al. showed that antipsychotic chlorpromazine has the potential to be a repurposed drug for breast cancer treatment. Among the potentially affected molecular targets, the lncRNA-mRNA interaction network has been heavily researched, as systematic analysis indicated that an lncRNA-mRNA co-expression relevant to platinum resistance in advanced serous ovarian cancer. Research of miRNA-lncRNA-mRNA interconnections also support significant academic, practical and clinical basis to gastric cancer. Moreover, Xiao et al. found that LINC0092 and chromosome 2 open reading frame 71 were correlated with better prognosis of breast cancer by analyzing the resultant ER subtype-related miRNA-lncRNA-mRNA network in breast and gastric cancer. Drawing on previous research, our research attempted to elucidate the mechanism of mangiferin in LUAD by analyzing the differentially expressed lncRNAs and mRNAs and constructing the network.
Thus, we considered three committed steps to achieve the goal. First, the lncRNAs and mRNAs that are differentially expressed after mangiferin treatment should be screened out. Second, a close association between identified common lncRNAs and mRNAs should be determined for lncRNA-mRNA network construction. Third, identification of target lncRNAs, target genes and meaningful lncRNA-mRNA pairs should be performed. Additionally, we investigated the potential mechanism by which the nodes in lncRNA-mRNA networks may be involved in the effects of mangiferin on LUAD.
Target lncRNAs and genes should be characterized as the probable targets affected by mangiferin in the network. Therefore, differentially expressed lncRNAs that have abundant connections with the mRNA group were considered. Similarly, to identify target genes, we added the protein interaction condition, as regulatory relationships among proteins have also been verified by large databases. However, when targeting these nodes, it is not clear whether mangiferin has an anticancer effect. Furthermore, for significant lncRNA-mRNA pair identification, which was predicted to be beneficial for LUAD prognosis after mangiferin treatment, DEGs of LUAD downloaded in GEPIA2 and displayed in Venn diagrams help establish links between laboratory results and databases. To elaborate, mangiferin should promote the dysregulated genes that suggest positive prognosis and inhibit those suggesting poor prognosis by upregulating or downregulating the expression levels. Consequently, the eligible genes and corresponding lncRNAs became meaningful targets for mangiferin to produce anticancer effects in LUAD.
According to the results, 12 lncRNAs were presented as targets. Based on NONCODE v5 (http://www.noncode.org), exosome expression profile analysis indicated that NONHSAT094064.2 is highly expressed in hepatocellular carcinoma cell lines, human umbilical vein endothelial cell lines and normal human blood. NONHSAT112849.2, NONHSAT099161.2 and NONHSAT176210.1 showed significant overexpression in the human umbilical vein endothelial cell line and the foreskin fibroblast cell line, while NONHSAT077537.2 was significantly present in the squamous cell carcinoma cell line and normal human blood. However, no studies have discussed these lncRNAs in detail, and to date, we have not found any basis in the published literature for demonstrating associations of these 12 lncRNAs with LUAD or mangiferin.
In addition, we extracted 18 target genes of mangiferin in LUAD, among which NGFR, RP11-203J24.9, RP11-1072A3.3, FGF11, DLX2 and EFNB3 were upregulated, while ANXA3, TSPAN8, RP11-473I1.9, SEMA3A, FRK, TOMM6, GEMIN2, CDK1, CXCL8, CCL2, HMGB1 and DDX58 were downregulated, by mangiferin treatment. NGFR was suggested to be involved in the switching of KRAS + LUAD to squamous cell carcinoma when highly expressed. Studies have shown that suppression of EFNB3 decreases NSCLC progression, but no evidence has been found in LUAD[47, 48]. ANXA3 knockdown was found to inhibit the growth, migration, invasion, and metastasis of LUAD via in vitro and in vivo experiments[49, 50]. Moreover, research has indicated TSPAN8 to be a diagnostic biomarker in lung cancer . Zhou et al. found that A549 cells secrete SEMA3A to inhibit the maturation and functions of dendritic cells, which might be associated with the unidentified mechanism of immune evasion by tumor cells. Interestingly, FRK was considered to be a underlying treatment target for drug discovery, as it has a carcinogenic effect in lung cancer cells via inducing metabolic reprogramming and finally promoting epithelial-mesenchymal transition and metastasis. TOMM6 is an upregulated mRNA-related lncRNA UCA1 that might affect cisplatin resistance in LUAD. CDK1 was found to be an adverse prognostic and diagnostic biomarker for LUAD[55, 56]. Liu et al. found that CXCL8 played an adverse role which accelerating cancer progression and bad outcome of LUAD, while human Dachshund homologue 1 antagonized CXCL8 to enhance the survival of LUAD patients. Moreover, high levels of CCL2 predict unfavorable survival in lung adenocarcinoma, and HMGB1-regulated autophagy was proven to be a significant contributor to docetaxel resistance in LUAD cells. In summary, most of these genes play roles in LUAD, at least in lung cancer. However, few or no publications have reported the associations of these genes with mangiferin. Only HMGB1, whose protein expression rate was decreased by mangiferin, effectively prevented alcohol hepatitis . Therefore, further validation is needed.
In the significant lncRNA-mRNA pairs that contained ARHGAP29, BRIX1, CD109, CDK1, CTNNAL1, DAB2IP, DDIT4L, GPR162, ICAM5, KCNAB3 and MMP7, Shukla et al. presented the first RNA-seq prognostic signature for LUAD, including CD109 . The genovariation of DAB2IP/AIP1 is related to increasing the risk of lung cancer in Chinese males. Similarly, another study revealed that an elevated circulating tumor cell count and overexpression of MMP7 correlate with metastasis and clinical progression in LUAD patients. However, most of the significant genes predicted in our study, which are related to neither LUAD nor mangiferin, still lack literature validation, and the regulatory mechanism governing the lncRNA-mRNA pairs warrants further exploration.
Potential pathway analysis under the lncRNA-mRNA network was also performed. KEGG analysis demonstrated that mangiferin was mostly centralized in the PI3K-Akt signaling pathway (P < 0.01) when LUAD cells were treated. The PI3K-Akt signaling pathway, involving the key proteins phosphatidylinositol 3-kinase (PI3K) and Akt/Protein Kinase B, is an intracellular signal transduction road that promotes metabolism, hyperplasia, cell survival, growth and angiogenesis through responsing to extracellular signals. Dysregulation of the PI3K/Akt pathway is implicated in a number of human cancers[64–67]. Studies of the PI3K-Akt signaling pathway may also help to develop targeted medicine for LUAD. For example, Zhang et al. suggested 20(S)-protopanaxadiol (PPD) as a promising chemopreventive agent that downregulated the PI3K/Akt signaling pathway in A549 cells. It was also indicated that allicin may inhibit invasion of LUAD by reducing the activity of the PI3K/AKT signaling pathway, and baicalein may increase cisplatin sensitivity of A549 cells via the PI3K/Akt/NF-κB pathway. On the other hand, it was reported that mangiferin relieves lipopolysaccharide-induced injury by activating the PI3K/AKT pathway. mangiferin also inhibits the MMP-9 gene in phorbol myristate acetate-stimulated human astroglioma, in which the PI3K/AKT pathway is involved. Therefore, we demonstrated that mangiferin may influence the prognosis of LUAD patients by regulating the PI3K/AKT signaling pathway.