The Journal of Nutritional Biochemistry

Dietary compound glycyrrhetinic acid suppresses tumor angiogenesis and growth by modulating antiangiogenic and proapoptotic pathways in vitro and in vivo

Glycyrrhetinic acid (GA) is a major bioactive compound of licorice. The objective of this study was to investigate the effects of GA on ovarian cancer, particularly those related to angiogenesis and apoptosis, and to elucidate the underlying mechanisms of action. In vitro studies showed that GA significantly inhibited proliferation, migration, invasion and tube formation in human umbilical vein endothelial cells (HUVECs) in a concentration-dependent manner. GA inhibited the phosphorylation of major receptors and enzymes involved in angiogenesis, such as VEGFR2, mTOR, Akt, ERK1/2, MEK1/2, p38 and JNK1/2 in HUVECs. In addition, GA induced apoptosis, loss of mitochondrial membrane potential and cell cycle arrest in G1 phase in A2780 ovarian cancer cells. The proapoptotic effect of GA involved the increased phosphorylation of p38 and JNK1/2; increased cleavage of caspase 3, caspase 9 and PARP; reduced phosphorylation of mTOR, Akt and ERK1/2; and reduced expressions of survivin and cyclin D1. Ex vivo studies showed that GA significantly inhibited microvessel sprouting in rat aortic ring model. In vivo studies showed that GA inhibited the formation of new blood vessels in zebrafish and mouse Matrigel plug. GA also significantly reduced the size of ovarian cancer xenograft tumors in nude mice. Taken together, GA possesses potential antitumor effects, and the underlying mechanisms may involve the inhibition of signaling pathways related to angiogenesis and the activation of apoptotic pathways in cancer cells. Our findings suggest that GA could serve as an effective regimen in the prevention or treatment of cancer.

Functional targeting of the TGF-βR1 kinase domain and downstream signaling: A role for the galloyl moiety of green tea-derived catechins in ES-2 ovarian clear cell carcinoma

The galloyl moiety is a specific structural feature which dictates, in part, the chemopreventive properties of diet-derived catechins. In ovarian cancer cells, galloylated catechins were recently demonstrated to target the transforming growth factor (TGF)-β-mediated control of the epithelial-mesenchymal transition process. The specific impact of the galloyl moiety on such signaling, however, remains poorly understood. Here, we questioned whether the sole galloyl moiety interacted with TGF-β-receptors to alter signal transduction and chemotactic migratory response in an ES-2 serous carcinoma-derived ovarian cancer cell model. In line with the LogP and LogS values of the tested molecules, we found that TGF-β-induced Smad-3 phosphorylation and cell migration were optimally inhibited, provided that the lateral aliphatic chain of the galloyl moiety reached 8-10 carbons. Functional inhibition of the TGF-β receptor (TGF-βR1) kinase activity was supported by surface plasmon resonance assays showing direct physical interaction between TGF-βR1 and the galloyl moiety. In silico molecular docking analysis predicted a model where galloylated catechins may bind TGF-βR1 within its adenosine triphosphate binding cleft in a site analogous to that of Galunisertib, a selective adenosine triphosphate-mimetic competitive inhibitor of TGF-βR1. In conclusion, our data suggest that the galloyl moiety of the diet-derived catechins provides specificity of action to galloylated catechins by positioning them within the kinase domain of the TGF-βR1 in order to antagonize TGF-β-mediated signaling that is required for ovarian cancer cell invasion and metastasis.

Folate deficiency promotes cervical squamous carcinoma SiHa cells progression by targeting miR-375/FZD4/β-catenin signaling

Epidemiological studies suggest an association between folate deficiency (FD) and cervical squamous cell carcinoma (SCC) progression. However, the underlying mechanism is unclear. Our study showed that FD-driven downregulation of miR-375 promoted proliferation of SCC SiHa cells and progression of xenograft tumors developed from SiHa; however, the exact mechanism of this process remained unclear. The current study aimed to elucidate the underlying mechanisms by which FD promotes the progression of SiHa cells by downregulating miR-375 expression. The results showed that miR-375 acted as a suppressor of SCC and inhibited the proliferation, migration, and invasion of SiHa cells. The FZD4 gene was identified as a target gene of miR-375, which can reverse the anti-onco effect of miR-375 and promote the proliferation and migration of SiHa cells. Furthermore, the regulatory effects of miR-375 and FZD4 on SiHa cells may be achieved by activating the β-catenin signaling pathway. Moreover, FD may regulate the expression of miR-375 by regulating its DNA methylation level in the promoter region. In conclusion, our study reveals that FD regulates the miR-375/FZD4 axis by increasing the methylation of the miR-375 promoter, thereby activating β-catenin signaling to promote SiHa cells progression. This study may provide new insights into the role of folic acid in the prevention and treatment of SCC.

Formononetin represses cervical tumorigenesis by interfering with the activation of PD-L1 through MYC and STAT3 downregulation

A. membranaceus is a traditional Chinese medicine that regulates blood sugar levels, suppresses inflammation, protects the liver, and enhances immunity. In addition, A. membranaceus is also widely used in diet therapy and is a well-known health tonic. Formononetin is a natural product isolated from A. membranaceus that has multiple biological functions, including anti-cancer activity. However, the mechanism by which formononetin inhibits tumor growth is not fully understood. In this present study, we demonstrated that formononetin suppresses PD-L1 protein synthesis via reduction of MYC and STAT3 protein expression. Furthermore, formononetin markedly reduced the expression of MYC protein via the RAS/ERK signaling pathway and inhibited STAT3 activation through JAK1/STAT3 pathway. Co-immunoprecipitation experiments illustrated that formononetin suppresses protein expression of PD-L1 by interfering with the interaction between MYC and STAT3. Meanwhile, formononetin promoted PD-L1 protein degradation via TFEB and TFE3-mediated lysosome biogenesis. T cell killing assay revealed that formononetin could enhance the activity of cytotoxic T lymphocytes (CTLs) and restore ability to kill tumor cells in a co-culture system of T cells and tumor cells. In addition, formononetin inhibited cell proliferation, tube formation, cell migration, and promoted tumor cell apoptosis by suppressing PD-L1. Finally, the inhibitory effect of formononetin on tumor growth was confirmed in a murine xenograft model. The present study revealed the anti-tumor potential of formononetin, and the findings should support further research and development of anti-cancer drugs for cervical cancer.