Quercetin Inhibits Cell Survival and Metastatic Ability via the EMT-mediated Pathway in Oral Squamous Cell Carcinoma

Evaluating the effects of various ethanolic medicinal plant extracts on metastatic breast cancer proliferation, invasion, and expression of a novel potential drug target; CD82 metastatic suppressor protein, and on in vivo angiogenesis using the ex ovo yolk sac membrane (YSM) assay

PURPOSE

Breast cancer metastasis relies on cellular invasion and angiogenesis facilitated by the downregulation of metastatic suppressor proteins like Cluster of Differentiation 82 (CD82). Currently, no medicines target multiple systems to prevent metastatic progression through CD82 upregulation. This study screened for plant extracts displaying effects on cell proliferation, invasion, and CD82 expression in breast cancer cells, and in vivo angiogenesis, and further correlated between the biological activities and effect on CD82 expression.

METHODS

Seventeen ethanolic plant extracts were screened for their effect on cell proliferation (against MDA-MB-231 and MCF-7 breast cancer and Hek293 kidney cells), cell invasion and effect on CD82 expression in metastatic MDA-MB-231 cells. Selected extracts were further evaluated for in vivo anti-angiogenesis.

RESULTS

Extracts displayed varying antiproliferative activity against the different cell lines, and those that showed selectivity indexes (SI) > 0.5 against MDA-MB-231 were selected for anti-invasion evaluation. Buddleja saligna Willd. (BS), Combretum apiculatum Sond. (CA), Foeniculum vulgare, Greyia radlkoferi, Gunnera perpensa and Persicaria senegalensis (Meisn.) Soják (PS) displayed 50% inhibitory concentration (IC50) values of 44.46 ± 3.46, 74.00 ± 4.48, 180.43 ± 4.51, 96.97 ± 2.29, 55.29 ± 9.88 and 243.60 ± 2.69 µg/mL, respectively against MDA-MB-231, and compared to Hek293 showed SI of 0.9, 0.7, 1.4, 1.1, 2.2 and 0.5. Significant invasion inhibition was observed at both 20 and 40 µg/mL for BS (94.10 ± 0.74 and 96.73 ± 0.95%) and CA (87.42 ± 6.54 and 98.24 ± 0.63%), whereas GR (14.91 ± 1.62 and 41 ± 1.78%) and PS (36.58 ± 0.54 and 51.51 ± 0.83%), only showed significant inhibition at 40 µg/mL, and FV (< 5% inhibition) and GP (10 ± 1.03 and 22 ± 1.31%) did not show significant inhibition at both concentrations. Due to the significant anti-invasive activity of BS, CA and PS at 40 µg/mL, these extracts were further evaluated for their potential to stimulate CD82. BS showed significant (p < 0.05) reduction in CD82 at 20 and 40 µg/mL (13.2 ± 2.2% and 20.3 ± 1.5% decrease, respectively), whereas both CA and PS at 20 µg/mL increased (p < 0.05) CD82 expression (16.4 ± 0.8% and 5.4 ± 0.6% increase, respectively), and at 40 µg/mL significantly reduced CD82 expression (23.4 ± 3.1% and 11.2 ± 2.9% decrease, respectively). Using the yolk sac membrane assay, BS (59.52 ± 4.12 and 56.72 ± 3.13% newly formed vessels) and CA (83.33 ± 3.17 and 74.00 ± 2.12%) at both 20 and 40 µg/egg showed significant (p < 0.001) angiogenesis inhibition, with BS showing statistical similar activity to the positive control, combretastatin A4 (10 nmol/egg), whereas PS only displayed significant (p < 0.001) angiogenesis stimulation at 40 µg/egg (120.81 ± 3.34% newly formed vessels).

CONCLUSION

BS exhibits antiproliferative, anti-invasive, and anti-angiogenic activity despite inhibiting CD82, suggesting an alternative mode of action. CA at 20 µg/mL shows moderate anti-invasive and anti-angiogenic potential by stimulating CD82, while at 40 µg/mL it still displays these properties but inhibits CD82, suggesting an additional mode of action. PS, with the least antiproliferative activity, stimulates CD82 and inhibits angiogenesis at 20 µg/mL but inhibits CD82 and increases angiogenesis at 40 µg/mL, indicating CD82 targeting as a major mode of action. Future studies should explore breast cancer xenograft models to assess the extracts' impact on CD82 expression and angiogenesis in the tumor microenvironment, along with isolating bioactive compounds from the extracts.

About a Possible Impact of Endodontic Infections by Fusobacterium nucleatum or Porphyromonas gingivalis on Oral Carcinogenesis: A Literature Overview

Periodontitis is linked to the onset and progression of oral squamous cell carcinoma (OSCC), an epidemiologically frequent and clinically aggressive malignancy. In this context, Fusobacterium (F.) nucleatum and Porphyromonas (P.) gingivalis, two bacteria that cause periodontitis, are found in OSCC tissues as well as in oral premalignant lesions, where they exert pro-tumorigenic activities. Since the two bacteria are present also in endodontic diseases, playing a role in their pathogenesis, here we analyze the literature searching for information on the impact that endodontic infection by P. gingivalis or F. nucleatum could have on cellular and molecular events involved in oral carcinogenesis. Results from the reviewed papers indicate that infection by P. gingivalis and/or F. nucleatum triggers the production of inflammatory cytokines and growth factors in dental pulp cells or periodontal cells, affecting the survival, proliferation, invasion, and differentiation of OSCC cells. In addition, the two bacteria and the cytokines they induce halt the differentiation and stimulate the proliferation and invasion of stem cells populating the dental pulp or the periodontium. Although most of the literature confutes the possibility that bacteria-induced endodontic inflammatory diseases could impact on oral carcinogenesis, the papers we have analyzed and discussed herein recommend further investigations on this topic.

Plant-Derived Bioactive Compounds: Exploring Neuroprotective, Metabolic, and Hepatoprotective Effects for Health Promotion and Disease Prevention

There is a growing trend among consumers to seek out natural foods and products with natural ingredients. This shift in consumer preferences had a direct impact on both food and pharmaceutical industries, leading to a focus of scientific research and commercial efforts to meet these new demands. The aim of this work is to review recent available scientific data on foods of interest, such as the artichoke, gooseberry, and polygonoideae plants, as well as olive oil and red raspberries. Interestingly, the urgency of solutions to the climate change emergency has brought new attention to by-products of grapevine bunch stem and cane, which have been found to contain bioactive compounds with potential health benefits. There is a pressing need for a faster process of translating scientific knowledge from the laboratory to real-world applications, especially in the face of the increasing societal burden associated with non-communicable diseases (NCDs), environmental crises, the post-pandemic world, and ongoing violent conflicts around the world.

Application of Natural Medicinal Plants Active Ingredients in Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC) is the most common malignant cancer of the head and neck, with high morbidity and mortality, ranking as the sixth most common cancer in the world. The treatment of OSCC is mainly radiotherapy, chemotherapy and surgery, however, the prognosis of patients is still poor and the recurrence rate is high. This paper reviews the range of effects of natural medicinal plant active ingredients (NMPAIs) on OSCC cancer, including the types of NMPAIs, anti-cancer mechanisms, involved signaling pathways, and clinical trials. The NMPAIs include terpenoids, phenols, flavonoids, glycosides, alkaloids, coumarins, and volatile oils. These active ingredients inhibit proliferation, induce apoptosis and autophagy, inhibit migration and invasion of OSCC cells, and regulate cancer immunity to exert anti-cancer effects. The mechanism involves signaling pathways such as mitogen-activated protein kinase, phosphatidylinositol 3 kinase/protein kinase B, nuclear factor kappa B, miR-22/WNT1/β-catenin and Nrf2/Keap1. Clinically, NMPAIs can inhibit the growth of OSCC, and the combined drug is more effective. Natural medicinal plants are promising candidates for the treatment of OSCC.

Berries vs. Disease: Revenge of the Phytochemicals

Secondary metabolites and phytochemicals in plant-based diets are known to possess properties that inhibit the development of several diseases including a variety of cancers of the aerodigestive tract. Berries are currently of high interest to researchers due to their high dietary source of phytochemicals. Black raspberries (BRB), Rubus occidentalis, are of special interest due to their rich and diverse composition of phytochemicals. In this review, we present the most up-to-date preclinical and clinical data involving berries and their phytochemicals in the chemoprevention of a variety of cancers and diseases. BRBs possess a variety of health benefits including anti-proliferative properties, anti-inflammatory activity, activation of pro-cell-death pathways, modulation of the immune response, microbiome modulation, reduction in oxidative stress, and many more. However, little has been done in both preclinical and clinical settings on the effects of BRB administration in combination with other cancer therapies currently available for patients. With the high potential for BRBs as chemopreventive agents, there is a need to investigate their potential in combination with other treatments to improve therapeutic efficacy.

Design, Synthesis, and Biological Evaluation of Novel Quercetin Derivatives as PPAR-γ Partial Agonists by Modulating Epithelial-Mesenchymal Transition in Lung Cancer Metastasis

Epithelial-to-mesenchymal transition (EMT) is responsible for driving metastasis of multiple cancer types including lung cancer. Peroxisome proliferator-activated receptor (PPAR)-γ, a ligand-activated transcription factor, controls expression of variety of genes involved in EMT. Although several synthetic compounds act as potent full agonists for PPAR-γ, their long term application is restricted due to serious adverse effects. Therefore, partial agonists involving reduced and balanced PPAR-γ activity are more effective and valued. A previous study discerned the efficacy of quercetin and its derivatives to attain favorable stabilization with PPAR-γ. Here this work is extended by synthesizing five novel quercetin derivatives (QDs) namely thiosemicarbazone (QUETSC)) and hydrazones (quercetin isonicotinic acid hydrazone (QUEINH), quercetin nicotinic acid hydrazone (QUENH), quercetin 2-furoic hydrazone (QUE2FH), and quercetin salicyl hydrazone (QUESH)) and their effects are analyzed in modulating EMT in lung cancer cell lines via PPAR-γ partial activation. QDs-treated A549 cells diminish cell proliferation strongly at nanomolar concentration compared to NCI-H460 cells. Of the five screened derivatives, QUETSC, QUE2FH, and QUESH exhibit the property of partial activation as compared to the overexpressive level of rosiglitazone. Consistently, these QDs also suppress EMT process by markedly downregulating the levels of mesenchymal markers (Snail, Slug, and zinc finger E-box binding homeobox 1) and concomitant upregulation of epithelial marker (E-cadherin).

Effective inhibition of breast cancer stem cell properties by quercetin-loaded solid lipid nanoparticles via reduction of Smad2/Smad3 phosphorylation and β-catenin signaling pathway in triple-negative breast cancer

BACKGROUND

The presence of cancer stem cells (CSCs) is a major cause of resistance to cancer therapy and recurrence. Triple-negative breast cancer (TNBC) is a subtype that responds poorly to therapy, making it a significant global health issue. Quercetin (QC) has been shown to affect CSC viability, but its low bioavailability limits its clinical use. This study aims to increase the effectiveness of QC in inhibiting CSC generation by using solid lipid nanoparticles (SLNs) in MDA-MB231 cells.

MATERIALS AND METHODS

After treating MCF-7 and MDA-MB231 cells with 18.9 μM and 13.4 μM of QC and QC-SLN for 48 h, respectively, cell viability, migration, sphere formation, protein expression of β-catenin, p-Smad 2 and 3, and gene expression of EMT and CSC markers were evaluated.

RESULTS

The QC-SLN with particle size of 154 nm, zeta potential of -27.7 mV, and encapsulation efficacy of 99.6% was found to be the most effective. Compared to QC, QC-SLN significantly reduced cell viability, migration, sphere formation, protein expression of β-catenin and p-Smad 2 and 3, and gene expression of CD₄₄, zinc finger E-box binding homeobox 1 (ZEB1), vimentin, while increasing the gene expression of E-cadherin.

CONCLUSIONS

Our findings demonstrate that SLNs improve the cytotoxic effect of QC in MDA-MB231 cells by increasing its bioavailability and inhibiting epithelial-mesenchymal transition (EMT), thereby effectively inhibiting CSC generation. Therefore, SLNs could be a promising new treatment for TNBC, but more in vivo studies are needed to confirm their efficacy.

Quercetin Suppresses Human Glioblastoma Migration and Invasion via GSK3β/β-catenin/ZEB1 Signaling Pathway

High invasiveness is a biological and clinical characteristic of glioblastoma and predicts poor prognosis of patients. Quercetin, a natural flavonoid compound, exhibits anticancer activity. However, we have a limited understanding of the possible underlying mechanism of quercetin in glioblastoma. In this study, we investigated the anticancer effect of quercetin in human glioblastoma cells. Our results showed that quercetin markedly suppressed the viability of glioblastoma cells in vitro and in vivo, and significantly inhibited glioblastoma cell migration and invasion. Moreover, quercetin reversed EMT-like mesenchymal phenotype and reduced the expression levels of EMT-related markers. Furthermore, we found that quercetin suppressed GSK-3β/β-catenin/ZEB1 signaling in glioblastoma. Taken together, our results demonstrate that quercetin inhibited migration and invasion of human glioma cells by suppressing GSK3β/β-catenin/ZEB1 signaling. Our study provides evidence that quercetin is a promising therapeutic natural compound to treat glioblastoma.

STAT3-EMT axis in tumors: modulation of cancer metastasis, stemness and therapy response

Epithelial-to-mesenchymal transition (EMT) mechanism is responsible for metastasis of tumor cells and their spread to various organs and tissues of body, providing undesirable prognosis. In addition to migration, EMT increases stemness and mediates therapy resistance. Hence, pathways involved in EMT regulation should be highlighted. STAT3 is an oncogenic pathway that can elevate growth rate and migratory ability of cancer cells and induce drug resistance. The inhibition of STAT3 signaling impairs cancer progression and promotes chemotherapy-mediated cell death. Present review focuses on STAT3 and EMT interaction in modulating cancer migration. First of all, STAT3 is an upstream mediator of EMT and is able to induce EMT-mediated metastasis in brain tumors, thoracic cancers and gastrointestinal cancers. Therefore, STAT3 inhibition significantly suppresses cancer metastasis and improves prognosis of patients. EMT regulators such as ZEB1/2 proteins, TGF-β, Twist, Snail and Slug are affected by STAT3 signaling to stimulate cancer migration and invasion. Different molecular pathways such as miRNAs, lncRNAs and circRNAs modulate STAT3/EMT axis. Furthermore, we discuss how STAT3 and EMT interaction affects therapy response of cancer cells. Finally, we demonstrate targeting STAT3/EMT axis by anti-tumor agents and clinical application of this axis for improving patient prognosis.

Evaluation of Wound Healing and Antibacterial Potential of Greyia radlkoferi Szyszyl. Ethanolic Leaf Extract

Angiogenesis is an essential mechanism in both physiological and pathological functions, such as wound healing and cancer metastasis. Several growth factors mediate angiogenesis, including vascular endothelial growth factor (VEGF) and platelet derived growth factor (PDGF). This study evaluated the potential wound healing activity of Greyia radlkoferi Szyszyl (GR) and its effect on growth factors regulating angiogenesis. The ethanolic leaf extract of GR was evaluated for antibacterial activity against wound associated bacteria; Staphylococcus aureus and Pseudomonas aeruginosa. It exhibited antibacterial activity against two strains of S. aureus (ATCC 25293 and ATCC 6538) displaying a minimum inhibitory concentration (MIC) at 250 and 500 μg/ml, respectively. The antioxidant activity of the extract was investigated for nitric oxide (NO) scavenging activity and showed a fifty percent inhibitory concentration (IC₅₀) of 1266.5 ± 243.95 μg/ml. The extract was further investigated to determine its effect on the proliferation and modulation of growth factors secreted by human keratinocytes (HaCaT). Its effect on wound closure was evaluated using the scratch assay, where non-toxic concentrations were tested, as determined by the antiproliferative assay against HaCat cells (IC₅₀ > 400 μg/ml). Results showed that the extract significantly inhibited wound closure, with a percentage closure of 60.15 ± 1.41% (p < 0.05) and 49.52 ± 1.43% (p < 0.01) at a concentration of 50 and 100 μg/ml, respectively, when compared to the 0.25% Dimethyl sulfoxide vehicle control (65.86 ± 1.12%). Quantification of secreted growth factors from cell-free supernatant, collected from the scratch assay, revealed that the extract significantly decreased the concentration of platelet-derived growth factor (PDGF-AA) at both 50 (p < 0.05) and 100 μg/ml (p < 0.001) (443.08 ± 77.36 and 178.98 ± 36.60 pg/ml) when compared to the 0.25% DMSO vehicle control (538.33 ± 12.64 pg/ml). Therefore, whilst the extract showed antibacterial activity against wound associated bacteria, it did not induce wound healing but rather showed a significant inhibition of wound closure, which was confirmed by the inhibition of PDGF-AA, a major growth factor involved in angiogenesis. Therefore, the GR extract, should be considered for further investigation of anti-angiogenic and anti-metastatic properties against cancer cells.

Phytochemicals in Chemoprevention: A Cost-Effective Complementary Approach

Cancer is one of the leading causes of death across the world. Although conventional cancer treatments such as chemotherapy and radiotherapy have effectively decreased cancer progression, they come with many dose-limiting side-effects. Phytochemicals that naturally occur in spices, fruits, vegetables, grains, legumes, and other common foods are surprisingly effective complements to conventional cancer treatments. These biologically active compounds demonstrate anticancer effects via cell signaling pathway interference in cancerous cells. In addition, phytochemicals protect non-cancerous cells from chemotherapy-induced side-effects. This paper addresses the not only the potential of phytochemicals quercetin, isoflavones, curcumin, catechins, and hesperidin in terms of cancer treatment and protection against side-effects of chemotherapy, but also methods for increasing phytochemical bioavailability.

In Vitro Study of Two Edible Polygonoideae Plants: Phenolic Profile, Cytotoxicity, and Modulation of Keap1-Nrf2 Gene Expression

Polygonum aviculare and Persicaria amphibia (subfam. Polygonoideae) are used in traditional cuisines and folk medicine in various cultures. Previous studies indicated that phytochemicals obtained from Polygonoideae plants could sensitize chemoresistant cancer cells and enhance the efficacy of some cytostatics. Here, the cytotoxic properties of chemically characterized ethanol extracts obtained from P. aviculare and P. amphibia, individually and in combination with doxorubicin (D), were determined against hepatocarcinoma HepG2 cells. Phenolic composition, cell viability, cell cycle, apoptosis, and the expression of Keap1 and Nrf2 were examined by following methods: LC-MS/MS, LC-DAD-MS, MTT, flow cytometry, and qRT-PCR. Extracts were rich in dietary polyphenolics. Synergistic cytotoxicity was detected for extracts combined with D. The observed synergisms are linked to the interference with apoptosis, cell cycle, and expression of Keap1-Nrf2 genes involved in cytoprotection. The combined approach of extracts and D could emerge as a potential pathway of chemotherapy improvement.

Anticancer Potential of Selected Flavonols: Fisetin, Kaempferol, and Quercetin on Head and Neck Cancers

Flavonols are ones of the most common phytochemicals found in diets rich in fruit and vegetables. Research suggests that molecular functions of flavonoids may bring a number of health benefits to people, including the following: decrease inflammation, change disease activity, and alleviate resistance to antibiotics as well as chemotherapeutics. Their antiproliferative, antioxidant, anti-inflammatory, and antineoplastic activity has been proved. They may act as antioxidants, while preventing DNA damage by scavenging reactive oxygen radicals, reinforcing DNA repair, disrupting chemical damages by induction of phase II enzymes, and modifying signal transduction pathways. One of such research areas is a potential effect of flavonoids on the risk of developing cancer. The aim of our paper is to present a systematic review of antineoplastic activity of flavonols in general. Special attention was paid to selected flavonols: fisetin, kaempferol, and quercetin in preclinical and in vitro studies. Study results prove antiproliferative and proapoptotic properties of flavonols with regard to head and neck cancer. However, few study papers evaluate specific activities during various processes associated with cancer progression. Moreover, an attempt was made to collect the majority of substantive studies on bioactive potential of the selected flavonols, especially with regard to modulation of a range of signal transduction pathways that participate in cancer development.

The use of propolis in dentistry, oral health, and medicine: A review

BACKGROUND

Propolis is a resinous product that is collected from plants by bees to cover holes and crevices in their hives. Propolis has potent antibacterial, antiviral, anti-inflammatory, wound healing, and anticancer properties. Propolis has been used therapeutically by humans for centuries, including the treatment of dental caries and mouth infections.

HIGHLIGHT

This review article attempts to analyze the potential use of propolis in general dentistry and oral health management.

CONCLUSION

Propolis is potentially useful in dentistry and oral health management based on available in vitro, in vivo, and ex vivo studies, as well as human clinical trials.

Quercetin nanoformulations: a promising strategy for tumor therapy

Phytochemicals as dietary constituents are being widely explored for the prevention and treatment of various diseases. Quercetin, a major constituent of various dietary products, has attracted extensive interest due to its anti-proliferative capability, reversal of multidrug resistance, autophagy promotion and tumor microenvironment modulation on different cancer types. Although quercetin has shown potent medical value, its application as an antitumor drug is limited. Problems like poor solubility, bioavailability and stability, short half-life and weak tumor-targeting biodistribution make quercetin an unreliable candidate for cancer therapy. Nanoparticle based platforms have shown a number of advantages in delivering a hydrophobic drug like quercetin to diseased tissues. Quercetin nanoparticles have demonstrated high encapsulation efficiency, stability, sustained release, prolonged circulation time, improved accumulation at tumor sites and therapeutic efficiency. Moreover, a combination of quercetin with other diagnostic or therapeutic agents in one nanocarrier has achieved enhancements in detecting or treating tumors. In this review, we have tried to summarize the pharmacological activities of quercetin with regard to tumor cells and microenvironments in vitro and in vivo. Furthermore, various nanoformulations have been highlighted for quercetin delivery for cancer treatment. These results suggest that quercetin nanoparticles may be a promising antitumor therapeutic agent.