Kaempferol suppresses cell migration through the activation of the ERK signaling pathways in ARPE-19 cells

Tricetin suppresses the cell migration and BMP-6 expression through p38 signaling pathways in human retinal pigment epithelium cells

Proliferative vitreoretinopathy (PVR) is a visual-threatening disease, which cause from the migration of retinal pigment epithelium (RPE). Tricetin, a family of flavonoids, can inhibit the metastasis of several cancers. Herein, we aim to evaluate the possible effect of tricetin on inhibiting ARPE-19 cells migration. The Boyden chamber assay, wound healing assay, RNA sequencing, and Western blot analysis were applied in our experiment. The results revealed that tricetin inhibited the cell migration abilities of ARPE-19 cells. Moreover, using RNA sequencing technology, we revealed that tricetin repressed bone morphogenetic protein-6 (BMP-6) gene expressions in ARPE-19 cells. Overexpression of BMP-6 resulted in significant restoration of cell migration capabilities of tricetin-treated ARPE-19 cells. Furthermore, tricetin suppressed the phosphorylation of the p38 signaling pathway. Moreover, blocking the p38 pathway also inhibits BMP-6 expression and migration in the ARPE-19 cells. In conclusion, this study revealed that tricetin inhibits the ARPE-19 cell migration mainly via the suppression of BMP-6 expression and p38 signaling pathway.

Inhibition of hypoxia-inducible factors suppresses subretinal fibrosis

Age-related macular degeneration (AMD) is a common cause of vision loss. The aggressive form of AMD is associated with ocular neovascularization and subretinal fibrosis, representing a responsive outcome against neovascularization mediated by epithelial-mesenchymal transition of retinal pigment epithelium (RPE) cells. A failure of the current treatment (anti-vascular endothelial growth factor therapy) has also been attributed to the progression of subretinal fibrosis. Hypoxia-inducible factors (HIFs) increase gene expressions to promote fibrosis and neovascularization. HIFs act as a central pathway in the pathogenesis of AMD. HIF inhibitors may suppress ocular neovascularization. Nonetheless, further investigation is required to unravel the aspects of subretinal fibrosis. In this study, we used RPE-specific HIFs or von Hippel-Lindau (VHL, a regulator of HIFs) conditional knockout (cKO) mice, along with pharmacological HIF inhibitors, to demonstrate the suppression of subretinal fibrosis. Fibrosis was suppressed by treatments of HIF inhibitors, and similar suppressive effects were detected in RPE-specific Hif1a/Hif2a- and Hif1a-cKO mice. Promotive effects were observed in RPE-specific Vhl-cKO mice, where fibrosis-mediated pathologic processes were evident. Marine products' extracts and their component taurine suppressed fibrosis as HIF inhibitors. Our study shows critical roles of HIFs in the progression of fibrosis, linking them to the potential development of therapeutics for AMD.

The Anticancer Potential of Kaempferol: A Systematic Review Based on In Vitro Studies

Given the heterogeneity of different malignant processes, planning cancer treatment is challenging. According to recent studies, natural products are likely to be effective in cancer prevention and treatment. Among bioactive flavonoids found in fruits and vegetables, kaempferol (KMP) is known for its anti-inflammatory, antioxidant, and anticancer properties. This systematic review aims to highlight the potential therapeutic effects of KMP on different types of solid malignant tumors. This review was conducted following the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines. Searches were performed in EMBASE, Medline/PubMed, Cochrane Collaboration Library, Science Direct, Scopus, and Google Scholar. After the application of study criteria, 64 studies were included. In vitro experiments demonstrated that KMP exerts antitumor effects by controlling tumor cell cycle progression, proliferation, apoptosis, migration, and invasion, as well as by inhibiting angiogenesis. KMP was also able to inhibit important markers that regulate epithelial-mesenchymal transition and enhanced the sensitivity of cancer cells to traditional drugs used in chemotherapy, including cisplatin and 5-fluorouracil. This flavonoid is a promising therapeutic compound and its combination with current anticancer agents, including targeted drugs, may potentially produce more effective and predictable results.

Molecular pathogenesis of subretinal fibrosis in neovascular AMD focusing on epithelial-mesenchymal transformation of retinal pigment epithelium

Age-related macular degeneration (AMD) is a leading cause of vision loss among elderly people in developed countries. Neovascular AMD (nAMD) accounts for more than 90% of AMD-related vision loss. At present, intravitreal injection of anti-vascular endothelial growth factor (anti-VEGF) is widely used as the first-line therapy to decrease the choroidal and retinal neovascularizations, and thus to improve or maintain the visual acuity of the patients with nAMD. However, about 1/3 patients still progress to irreversible visual impairment due to subretinal fibrosis even with adequate anti-VEGF treatment. Extensive literatures support the critical role of epithelial-mesenchymal transformation (EMT) of retinal pigment epithelium (RPE) in the pathogenesis of subretinal fibrosis in nAMD, but the underlying mechanisms still remain largely unknown. This review summarized the molecular pathogenesis of subretinal fibrosis in nAMD, especially focusing on the transforming growth factor-β (TGF-β)-induced EMT pathways. It was also discussed how these pathways crosstalk and respond to signals from the microenvironment to mediate EMT and contribute to the progression of nAMD-related subretinal fibrosis. Targeting EMT signaling pathways might provide a promising and effective therapeutic strategy to treat subretinal fibrosis secondary to nAMD.

Flavonoids on the Frontline against Cancer Metastasis

Metastasis is the leading cause of death in cancer patients [...].

EF-24 inhibits TPA-induced cellular migration and MMP-9 expression through the p38 signaling pathway in cervical cancer cells

Diphenyl difluoroketone (EF-24), a synthetic curcumin analog, has enhanced bioavailability over curcumin. EF-24 acts more powerful bioactivity for anti-inflammatory and anti-cancer activity. However, the effects and mechanism of EF-24 on cervical cancer has not been fully investigated. Herein, this study evaluated the effects of EF-24 on TPA-induced cellular migration of cervical cancer. The results showed that EF-24 substantially reduced the cellular migration and cellular invasion of the HeLa and SiHa cells. Moreover, gelatin zymography, western blotting analyses and real-time PCR revealed that EF-24 suppressed Matrix metalloproteinase-9 (MMP-9) activity, protein expression and mRNA levels. Mechanistically, EF-24 inhibited the phosphorylation of the p38 signaling pathway. In conclusion, EF-24 inhibited TPA-induced cellular migration and cellular invasion of cervical cancer cell lines through modulating MMP-9 expression via downregulating signaling p38 pathway and EF-24 may have potential to serve as a chemopreventive agent of cervical cancer.

CCL3-CCR5 axis promotes cell migration and invasion of colon adenocarcinoma via Akt signaling pathway

BACKGROUND

Infiltration of tumor-associated macrophages (TAMs) can promote tumorigenesis and development. C-C motif chemokine ligand 3 (CCL3) was reported to be derived from TAMs and tumor cells and facilitate the progression of several cancers. Nevertheless, whether CCL3 can be derived from TAMs and tumor cells of colon adenocarcinoma (COAD) is unclarified.

METHODS

Peripheral blood monocytes-derived macrophages were polarized by the conditioned medium from COAD cells to establish TAM-like macrophages (TAM1/2). RT-qPCR and western blotting were used for detection of expression levels of CCL3 and its receptors C-C motif chemokine receptor 1 (CCR1) and CCR5 in TAM1/2 and COAD cells. Immunofluorescence staining was utilized for evaluating CCL3, CD163 and CCR5 expression. The Akt signaling pathway-associated protein levels were measured by western blotting. Transwell assays were used for assessing cell migration and invasiveness.

RESULTS

CCL3 displayed a high level in TAMs and cancer cells of COAD. CCL3 activated the Akt signaling pathway by binding to CCR5. CCL3-CCR5 axis facilitated COAD cell migration and invasiveness by activating the Akt signaling. CCL3 derived from both TAMs and cancer cells contributed to the malignant behaviors of COAD cells. High expression of CCL3/CCR5 was closely associated with poor prognoses of COAD patients.

CONCLUSION

CCL3-CCR5 interaction promotes cell migration and invasiveness, and functions as a prognostic biomarker for COAD.

CD82 attenuates TGF-β1-mediated epithelial-mesenchymal transition by blocking smad-dependent signaling in ARPE-19 cells

In retinal pigment epithelial (RPE) cells, transforming growth factor-beta (TGF-β) plays a critical role in epithelial-mesenchymal transition (EMT), which contributes to various fibrotic retinal disorders. In the present study, we investigated the effect of recombinant human cluster of differentiation 82 (rhCD82), a tumor metastasis suppressor, on TGF-β-induced EMT in the human RPE cell line APRE-19. The results show that TGF-β1 significantly enhanced cell migration, invasion and the expression of EMT-mediate factors in ARPE-19 cells. However, rhCD82 markedly inhibited cell mobility and the expression of epithelial marker, zonula occludens-1, as well as increased the expression of mesenchymal markers, such as vimentin and α-smooth muscle actin in TGF-β1-treated APRE-19 cells. In addition, TGF-β1 upregulated the phosphorylation of Smad, extracellular signal regulated kinase (ERK) and glycogen synthase kinase-3β (GSK-3β), but only phosphorylation of Smad was suppressed by rhCD82. Noteworthy, rhCD82 greatly suppressed the expression of TGF-β receptor I (TGFRI), TGFRII and integrins in TGF-β1-treated APRE-19 cells. In particular, the result of molecular docking analysis and structural modeling show that rhCD82 partially interacts with the TGF-β1 binding sites of TGFRI, TGFRII, integrin β1 and integrin αv. Taken together, this finding suggested that rhCD82 suppressed TGF-β1-induced EMT of RPE by blocking of Smad-dependent pathway, which is caused by rhCD82 interaction with TGFRs and integrins, suggesting new insight into CD82 as a potential therapeutic strategy in fibrotic retinal disorders.

Effect and mechanisms of kaempferol against endometriosis based on network pharmacology and in vitro experiments

Endometriosis is a common gynecological disease, and its underlying mechanisms remain elusive. Patients are at a higher risk of recurrence after surgery or drug withdrawal. In this study, to identify a potentially effective and safe therapy for endometriosis, we screened potential target genes of kaempferol on endometriosis using network pharmacology and further validation. Network pharmacology showed kaempferol may suppress migratory and invasive properties by modulating the phosphoinositide 3-kinase (PI3K) pathway and its downstream target matrix metalloproteinase (MMP)9. Furthermore, in vitro experiments showed that kaempferol repressed the migration and invasion of endometrial cells, and this effect may be involved in mediating the PI3K-related genes, phosphatase and tensin homolog (PTEN) and MMP9. Network pharmacology and in vitro experiments showed that kaempferol, repressed the implantation of endometrial cells and formation of ectopic lesions by inhibiting migration and invasion and regulating PTEN and MMP9, which may be associated with the PI3K pathway.

Kaempferol inhibits the cell migration of human hepatocellular carcinoma cells by suppressing MMP-9 and Akt signaling

Metastasis is the most prevalent cause of cancer-related deaths and treatment failure in patients with hepatocellular carcinoma (HCC). Kaempferol is a natural flavonol belonging to the subgroup of flavonoids and exhibits potent anticancer activities. This study provides molecular evidence on the anti-invasive and anti-migratory effects of kaempferol on human HCC cells. The anti-invasive effect was investigated by applying kaempferol on two human HCC cell lines (Huh-7 and SK-Hep-1). Kaempferol reduced the invasion and migration of Huh-7 and SK-Hep-1 cells by Boyden chamber invasion assay and wound healing assay, respectively. A protease array analysis showed that Matrix Metalloproteinase-9 (MMP-9) was dramatically downregulated in HCC cells after kaempferol treatment. Gelatin zymography and Western blot assay showed that kaempferol reduced the activities and protein expression of MMP-9, respectively. Kaempferol also sufficiently suppressed the phosphorylation of the Akt expression. Overall, kaempferol inhibited the invasive properties of human HCC cells by targeting MMP-9 and Akt pathways. Hence, kaempferol could be used as an adjuvant therapeutic agent for the treatment of human HCC cells.

Dihydromyricetin suppresses cell metastasis in human osteosarcoma through SP-1- and NF-κB-modulated urokinase plasminogen activator inhibition

BACKGROUND

Metastasis caused a decline in the 5-years survival rate of osteosarcoma. Therefore, developing new targeted therapeutics for osteosarcoma treatment is imperative. Dihydromyricetin (DHM) has several physiological functions: it counteracts inflammation, oxidation, and antitumor properties. However, the effects of DHM on osteosarcoma and its underlying mechanisms are still not well understood.

PURPOSE

In this study, we investigated the antimetastatic properties of DHM in human osteosarcoma U-2 OS and HOS cells.

METHODS

The effects of DHM (0, 25, 50, 75, and 100 μM) on cell viability, migration, and invasion were examined. Western blotting, RT-PCR, and quantitative real-time PCR (QPCR) were determined urokinase plasminogen activator (uPA) expression. The expression of transcriptional factor SP-1 and NF-κB was determined by using immunofluorescence assay, chromatin immunoprecipitation assay, and site-directed mutagenesis luciferase reporter.

RESULTS

We observed that DHM suppresses cell migration and invasion in osteosarcoma cell lines. In addition, DHM inhibits metastasis by downregulating urokinase plasminogen activator (uPA) expression. Moreover, real-time polymerase chain reaction and promoter activity assays revealed that DHM decreased uPA expression at transcription levels. Furthermore, the inhibition of uPA expression was associated with the suppression of SP-1 and NF-κB, which bind to the uPA promoter. Regardless of blocking or inducing the extracellular signal-regulated kinase (ERK) pathway, we verified that the DHM-related suppression of uPA and cell metastasis occurred through the p-ERK pathway.

CONCLUSION

We are the first study to propose that DHM suppresses osteosarcoma metastasis through the ERK pathway and through the suppression of SP-1 and NF-κB to inhibit downstream uPA expression. DHM is a potential therapeutic agent for antimetastatic therapy against osteosarcoma.

Dietary polyphenols suppress chronic inflammation by modulation of multiple inflammation-associated cell signaling pathways

The high failure rate of the reductionist approach to discover effective and safe drugs to treat chronic inflammatory diseases has led scientists to seek alternative ways. Recently, targeting cell signaling pathways has been utilized as an innovative approach to discover drug leads from natural products. Cell signaling mechanisms have been identified playing key role in diverse diseases by inducing proliferation, cell survival and apoptosis. Phytochemicals are known to be able to modulate the cellular and molecular networks which are associated to chronic diseases including cancer-associated inflammation. In this review, the roles of dietary polyphenols (apigenin, kaempferol, quercetin, curcumin, genistein, isoliquiritigenin, resveratrol and gallic acid) in modulating multiple inflammation-associated cell signaling networks are deliberated. Scientific databases on suppressive effects of the polyphenols on chronic inflammation via modulation of the pathways especially in the recent five years are gathered and critically analyzed. The polyphenols are able to modulate several inflammation-associated cell signaling pathways, namely nuclear factor-kappa β, mitogen activated protein kinases, Wnt/β-catenin and phosphatidylinositol 3-kinase and protein kinase B via selective actions on various components of the networks. The suppressive effects of the polyphenols on the multiple cell signaling pathways reveal their potential use in prevention and treatment of chronic inflammatory disorders. Understanding the mechanistic effects involved in modulation of the signaling pathways by the polyphenols is necessary for lead identification and development of future functional foods for prevention and treatment of chronic inflammatory diseases.

Antiangiogenic Activity of Flavonoids: A Systematic Review and Meta-Analysis

Abstract: An imbalance of angiogenesis contributes to many pathologies such as cancer, arthritis and retinopathy, hence molecules that can modulate angiogenesis are of considerable therapeutic importance. Despite many reports on the promising antiangiogenic properties of naturally occurring flavonoids, no flavonoids have progressed to the clinic for this application. This systematic review and meta-analysis therefore evaluates the antiangiogenic activities of a wide range of flavonoids and is presented in two sections. The first part of the study (Systematic overview) included 402 articles identified by searching articles published before May 2020 using ScienceDirect, PubMed and Web of Science databases. From this initial search, different classes of flavonoids with antiangiogenic activities, related pathologies and use of in vitro and/or in/ex vivo angiogenesis assays were identified. In the second part (Meta-analysis), 25 studies concerning the antiangiogenic evaluation of flavonoids using the in vivo chick chorioallantoic membrane (CAM) assay were included, following a targeted search on articles published prior to June 2020. Meta-analysis of 15 out of the 25 eligible studies showed concentration dependent antiangiogenic activity of six compared subclasses of flavonoids with isoflavones, flavonols and flavones being the most active (64 to 80% reduction of blood vessels at 100 µM). Furthermore, the key structural features required for the antiangiogenic activity of flavonoids were derived from the pooled data in a structure activity relationship (SAR) study. All in all, flavonoids are promising candidates for the development of antiangiogenic agents, however further investigations are needed to determine the key structural features responsible for their activity.

Anti-Cancer Potential of Cannabinoids, Terpenes, and Flavonoids Present in Cannabis

In recent years, and even more since its legalization in several jurisdictions, cannabis and the endocannabinoid system have received an increasing amount of interest related to their potential exploitation in clinical settings. Cannabinoids have been suggested and shown to be effective in the treatment of various conditions. In cancer, the endocannabinoid system is altered in numerous types of tumours and can relate to cancer prognosis and disease outcome. Additionally, cannabinoids display anticancer effects in several models by suppressing the proliferation, migration and/or invasion of cancer cells, as well as tumour angiogenesis. However, the therapeutic use of cannabinoids is currently limited to the treatment of symptoms and pain associated with chemotherapy, while their potential use as cytotoxic drugs in chemotherapy still requires validation in patients. Along with cannabinoids, cannabis contains several other compounds that have also been shown to exert anti-tumorigenic actions. The potential anti-cancer effects of cannabinoids, terpenes and flavonoids, present in cannabis, are explored in this literature review.

Flavonoids in Cancer Metastasis

Metastasis represents a serious complication in the treatment of cancer. Flavonoids are plant secondary metabolites exerting various health beneficiary effects. The effects of flavonoids against cancer are associated not only with early stages of the cancer process, but also with cancer progression and spread into distant sites. Flavonoids showed potent anti-cancer effects against various cancer models in vitro and in vivo, mediated via regulation of key signaling pathways involved in the migration and invasion of cancer cells and metastatic progression, including key regulators of epithelial-mesenchymal transition or regulatory molecules such as MMPs, uPA/uPAR, TGF-β and other contributors of the complex process of metastatic spread. Moreover, flavonoids modulated also the expression of genes associated with the progression of cancer and improved inflammatory status, a part of the complex process involved in the development of metastasis. Flavonoids also documented clear potential to improve the anti-cancer effectiveness of conventional chemotherapeutic agents. Most importantly, flavonoids represent environmentally-friendly and cost-effective substances; moreover, a wide spectrum of different flavonoids demonstrated safety and minimal side effects during long-termed administration. In addition, the bioavailability of flavonoids can be improved by their conjugation with metal ions or structural modifications by radiation. In conclusion, anti-cancer effects of flavonoids, targeting all phases of carcinogenesis including metastatic progression, should be implemented into clinical cancer research in order to strengthen their potential use in the future targeted prevention and therapy of cancer in high-risk individuals or patients with aggressive cancer disease with metastatic potential.

Recent insights into natural product inhibitors of matrix metalloproteinases

Members of the matrix metalloproteinase (MMP) family have biological functions that are central to human health and disease, and MMP inhibitors have been investigated for the treatment of cardiovascular disease, cancer and neurodegenerative disorders. The outcomes of initial clinical trials with the first generation of MMP inhibitors proved disappointing. However, our growing understanding of the complexities of the MMP function in disease, and an increased understanding of MMP protein architecture and control of activity now provide new opportunities and avenues to develop MMP-focused therapies. Natural products that affect MMP activities have been of strong interest as templates for drug discovery, and for their use as chemical tools to help delineate the roles of MMPs that still remain to be defined. Herein, we highlight the most recent discoveries of structurally diverse natural product inhibitors to these proteases.