Luteolin sensitises drug-resistant human breast cancer cells to tamoxifen via the inhibition of cyclin E2 expression

Lonicerae Japonicae Flos with the homology of medicine and food: a review of active ingredients, anticancer mechanisms, pharmacokinetics, quality control, toxicity and applications

Lonicerae Japonicae Flos (LJF, called Jinyinhua in China), comes from the dried flower buds or flowers to be opened of Lonicera japonica Thunb. in the Lonicera family. It has a long history of medicinal use and has a wide range of application prospects. As modern research advances, an increasing number of scientific experiments have demonstrated the anticancer potential of LJF. However, there is a notable absence of systematic reports detailing the anti-tumor effects of LJF. This review integrates the principles of Traditional Chinese Medicine (TCM) with contemporary pharmacological techniques, drawing upon literature from authoritative databases such as PubMed, CNKI, and WanFang to conduct a comprehensive study of LJF. Notably, a total of 507 compounds have been isolated and characterized from the plant to date, which include volatile oils, organic acids, flavonoids, iridoids, triterpenes and triterpenoid saponins. Pharmacological studies have demonstrated that LJF extract, along with components such as chlorogenic acid, luteolin, rutin, luteoloside, hyperoside and isochlorogenic acid, exhibits potential anticancer activities. Consequently, we have conducted a comprehensive review and summary of the mechanisms of action and clinical applications of these components. Furthermore, we have detailed the pharmacokinetics, quality control, and toxicity of LJF, while also discussing its prospective applications in the fields of biomedicine and preventive healthcare. It is hoped that these studies will provide valuable reference for the clinical research, development, and application of LJF.

Exploration of the sensitization effect of Chaihu Shugan powder on chemotherapy for triple-negative breast cancer and its active ingredients

Chemotherapy plays a crucial role in the clinical treatment of triple-negative breast cancer (TNBC), but drug resistance limits its clinical application. The active ingredients of Chaihu Shugan Powder (CSP; Bupleurum Liver-Coursing Powder), quercetin and luteolin, both belong to flavonoid compounds and have significant anti-tumor potential, which can promote chemotherapy sensitivity. However, the correlation between the two and TNBC paclitaxel (PTX) chemotherapy sensitivity is unknown. We collected herbal components of CSP from the TCMSP database, and screened effective molecules and corresponding targets. STRING database was utilized to construct a protein-protein interaction network combining effective molecules and target genes. The top 50 nodes ranked by affinity were chosen for subsequent functional analysis, and the drug-active ingredient-gene interaction network was established using Cytoscape software. Molecular docking was used to determine the small molecules that target TNBC PTX resistance. The "clusterProfiler" package was utilized for GO and KEGG enrichment analyses on the top 50 genes to determine the pathways affected by CSP. Cell counting and colony formation assays evaluated cell viability, IC50 values, and proliferation capacity. Flow cytometry tested PTX intracellular accumulation. Western blot assayed the expression of TNF pathway-related proteins. Active ingredients of CSP, quercetin and luteolin, could inhibit TNBC cell proliferation and promote PTX chemotherapy sensitization. Quercetin and luteolin repressed the TNF signaling pathway and promoted PTX chemotherapy sensitization. Quercetin and luteolin could inhibit TNBC cell proliferation and promote PTX chemotherapy sensitization through the TNF signaling pathway. Therefore, the use of quercetin and luteolin plus PTX treatment provides a prospective strategy for TNBC treatment.

Luteolin Protects Cardiomyocytes Cells against Lipopolysaccharide-Induced Apoptosis and Inflammatory Damage by Modulating Nlrp3

PURPOSE

In this article, we aimed to investigate the influences of luteolin on inflammatory injury to cardiomyocytes induced by lipopolysaccharide (LPS).

MATERIALS AND METHODS

H9c2 cells were pretreated with different concentrations of luteolin (10, 20, and 50 µM) for 12 h and then stimulated with 10 µg/mL LPS or no LPS for 6 h. Cell viability was detected by CCK-8 assay. Cell apoptosis was determined by flow cytometry. QRT-PCR and Western blotting were utilized to examine mRNA and protein levels. ELISA was used to determine the levels of monocyte chemoattractant protein-1, tumor necrosis factor-alpha, interleukin (IL)-6, IL-1β, and IL-18 in cell supernatants among different groups of H9c2 cells. Immunofluorescence was applied to evaluate reactive oxygen species formation in H9c2 cells. M-mode images of echocardiography, the ejection fraction test, fractional shortening test, end-systolic volume test, and end-diastolic volume test of mouse heart function were obtained by ultrasonic electrocardiogram.

RESULTS

Luteolin could alleviate inflammatory damage and inflammatory factor expression among LPS-induced H9c2 cells. Additionally, we found that luteolin decreased LPS-stimulated inflammatory damage in H9c2 cells by down-regulating NOD-like receptor family pyrin domain containing 3 (Nlrp3). Luteolin also improved myocardial function in mice treated with LPS and reduced myocardial relaxation. Luteolin reversed myocardial histological abnormalities in mice and reduced inflammation and cardiomyocyte apoptosis. Additionally, luteolin inhibited oxidative stress-mediated myocardial and systemic tissue damage in mice. Finally, luteolin reduced LPS-induced inflammatory damage in mouse cardiomyocytes by down-regulating Nlrp3.

CONCLUSION

We found that luteolin could reduce inflammatory damage to cardiomyocytes induced by LPS by down-regulating Nlrp3.

Influence of Olive Oil and Its Components on Breast Cancer: Molecular Mechanisms

Breast cancer is the most frequent malignant neoplasia and a leading cause of mortality in women worldwide. The Mediterranean diet has been proposed as a healthy dietary pattern with protective effects in several chronic diseases, including breast cancer. This diet is characterized by the consumption of abundant plant foods and olive oil as the principal source of fat, which is considered one of the main components with potential antioxidant, anti-inflammatory and anticancer effects. Extra-virgin olive oil (EVOO) has several bioactive compounds, mainly including monounsaturated fatty acids, triterpenes and polyphenols, such as phenolic alcohols (e.g., hydroxytyrosol), secoiridoids (e.g., oleuropein and oleocanthal), lignans (e.g., pinoresinol) or flavonoids (e.g., luteolin). While epidemiological evidence is still limited, experimental in vivo and in vitro data have shown a protective effect of this oil and its compounds on mammary carcinogenesis. Such effects account through complex and multiple mechanisms, including changes in epigenetics, transcriptome and protein expression that modulate several signaling pathways. Molecular targets of EVOO compounds have a role in the acquisition of cancer hallmarks. Although further research is needed to elucidate their beneficial effects on human prevention and progression of the disease, evidence points to EVOO in the context of the Mediterranean diet as a heathy choice, while EVOO components may be promising adjuvants in anticancer strategies.

Network Pharmacology-Based Dissection of the Comprehensive Molecular Mechanisms of the Herbal Prescription FDY003 Against Estrogen Receptor-Positive Breast Cancer

Estrogen receptor-positive breast cancer (ERPBC) is the commonest subtype of breast cancer, with a high prevalence, incidence, and mortality. Herbal drugs are increasingly being used to treat ERPBC, although their mechanisms of action are not fully understood. Therefore, in this study, we aimed to analyze the therapeutic properties of FDY003, a herbal anti-ERPBC prescription, using a network pharmacology approach. FDY003 decreased the viability of human ERPBC cells and sensitized them to tamoxifen, an endocrine drug that is widely used in the treatment of ERPBC. The network pharmacology analysis revealed 18 pharmacologically active components in FDY003 that may interact with and regulate 66 therapeutic targets. The enriched gene ontology terms for the FDY003 targets were associated with the modulation of cell survival and death, cell proliferation and growth arrest, and estrogen-associated cellular processes. Analysis of the pathway enrichment of the targets showed that FDY003 may target a variety of ERPBC-associated pathways, including the PIK3-Akt, focal adhesion, MAPK, and estrogen pathways. Overall, these data provide a comprehensive mechanistic insight into the anti-ERPBC activity of FDY003.

Development and Evaluations of Transdermally Delivered Luteolin Loaded Cationic Nanoemulsion: In Vitro and Ex Vivo Evaluations

Introduction: Luteolin (LUT) is natural flavonoid with multiple therapeutic potentials and is explored for transdermal delivery using a nanocarrier system. LUT loaded cationic nanoemulsions (CNE1–CNE9) using bergamot oil (BO) were developed, optimized, and characterized in terms of in vitro and ex vivo parameters for improved permeation. Materials and methods: The solubility study of LUT was carried out in selected excipients, namely BO, cremophor EL (CEL as surfactant), labrasol (LAB), and oleylamine (OA as cationic charge inducer). Formulations were characterized with globular size, polydispersity index (PDI), zeta potential, pH, and thermodynamic stability studies. The optimized formulation (CNE4) was selected for comparative investigations (% transmittance as %T, morphology, chemical compatibility, drug content, in vitro % drug release, ex vivo skin permeation, and drug deposition, DD) against ANE4 (anionic nanoemulsion for comparison) and drug suspension (DS). Results: Formulations such as CNE1–CNE9 and ANE4 (except CNE6 and CNE8) were found to be stable. The optimized CNE4 based on the lowest value of globular size (112 nm), minimum PDI (0.15), and optimum zeta potential (+26 mV) was selected for comparative assessment against ANE4 and DS. The %T values of CNE1–CNE9 were found to be ˃95% and CEL content slightly improved the %T value. The spherical CNE4 was compatible with excipients and showed % total drug content in the range of 97.9–99.7%. In vitro drug release values from CNE4 and ANE4 were significantly higher than DS. Moreover, permeation flux (138.82 ± 8.4 µg/cm²·h), enhancement ratio (8.23), and DD (10.98%) were remarkably higher than DS. Thus, ex vivo parameters were relatively high as compared to DS which may be attributed to nanonization, surfactant-mediated reversible changes in skin lipid matrix, and electrostatic interaction of nanoglobules with the cellular surface. Conclusion: Transdermal delivery of LUT can be a suitable alternative to oral drug delivery for augmented skin permeation and drug deposition.

Chemoresistance in Ovarian Cancer: Prospects for New Drugs

This review focuses on the conventional treatment, signaling pathways and various reasons for drug resistance with an understanding of novel methods that can lead to effective therapies. Ovarian cancer is amongst the most common gynecological and lethal cancers in women affecting different age groups (20-60). The survival rate is limited to 5 years due to diagnosis in subsequent stages with a reoccurrence of tumor and resistance to chemotherapeutic therapy. The recent clinical trials use the combinatorial treatment of carboplatin and paclitaxel on ovarian cancer after the cytoreduction of the tumor. Predominantly, patients are responsive initially to therapy and later develop metastases due to drug resistance. Chemotherapy also leads to drug resistance causing enormous variations at the cellular level. Multifaceted mechanisms like drug resistance are associated with a number of genes and signaling pathways that process the proliferation of cells. Reasons for resistance include epithelial-mesenchyme, DNA repair activation, autophagy, drug efflux, pathway activation, and so on. Determining the routes on the molecular mechanism that target chemoresistance pathways are necessary for controlling the treatment and understanding efficient drug targets can open light on improving therapeutic outcomes. The most common drug used for ovarian cancer is Cisplatin that activates various chemoresistance pathways, ultimately causing drug resistance. There have been substantial improvements in understanding the mechanisms of cisplatin resistance or chemo sensitizing cisplatin for effective treatment. Therefore, using therapies that involve a combination of phytochemical or novel drug delivery system would be a novel treatment for cancer. Phytochemicals are plant-derived compounds that exhibit anti-cancer, anti-oxidative, anti-inflammatory properties and reduce side effects exerted by chemotherapeutics.

A Network Pharmacology Study on the Molecular Mechanisms of FDY003 for Breast Cancer Treatment

Herbal medicines have drawn considerable attention with regard to their potential applications in breast cancer (BC) treatment, a frequently diagnosed malignant disease, considering their anticancer efficacy with relatively less adverse effects. However, their mechanisms of systemic action have not been understood comprehensively. Based on network pharmacology approaches, we attempted to unveil the mechanisms of FDY003, an herbal drug comprised of Lonicera japonica Thunberg, Artemisia capillaris Thunberg, and Cordyceps militaris, against BC at a systemic level. We found that FDY003 exhibited pharmacological effects on human BC cells. Subsequently, detailed data regarding the biochemical components contained in FDY003 were obtained from comprehensive herbal medicine-related databases, including TCMSP and CancerHSP. By evaluating their pharmacokinetic properties, 18 chemical compounds in FDY003 were shown to be potentially active constituents interacting with 140 BC-associated therapeutic targets to produce the pharmacological activity. Gene ontology enrichment analysis using g:Profiler indicated that the FDY003 targets were involved in the modulation of cellular processes, involving the cell proliferation, cell cycle process, and cell apoptosis. Based on a KEGG pathway enrichment analysis, we further revealed that a variety of oncogenic pathways that play key roles in the pathology of BC were significantly enriched with the therapeutic targets of FDY003; these included PI3K-Akt, MAPK, focal adhesion, FoxO, TNF, and estrogen signaling pathways. Here, we present a network-perspective of the molecular mechanisms via which herbal drugs treat BC.

Participation of MicroRNAs in the Treatment of Cancer with Phytochemicals

Cancer is a global health concern and one of the main causes of disease-related death. Even with considerable progress in investigations on cancer therapy, effective anti-cancer agents and regimens have thus far been insufficient. There has been compelling evidence that natural phytochemicals and their derivatives have potent anti-cancer activities. Plant-based anti-cancer agents, such as etoposide, irinotecan, paclitaxel, and vincristine, are currently being applied in medical treatments for patients with cancer. Further, the efficacy of plenty of phytochemicals has been evaluated to discover a promising candidate for cancer therapy. For developing more effective cancer therapy, it is required to apprehend the molecular mechanism deployed by natural compounds. MicroRNAs (miRNAs) have been realized to play a pivotal role in regulating cellular signaling pathways, affecting the efficacy of therapeutic agents in cancer. This review presents a feature of phytochemicals with anti-cancer activity, focusing mainly on the relationship between phytochemicals and miRNAs, with insights into the role of miRNAs as the mediators and the regulators of anti-cancer effects of phytochemicals.

A bioinformatics investigation into the pharmacological mechanisms of javanica oil emulsion injection in non-small cell lung cancer based on network pharmacology methodologies

Background

Javanica oil emulsion injection (JOEI) is an effective therapeutic option for patients with non-small cell lung cancer (NSCLC), but its mechanisms have not been fully elucidated.

Methods

In this study, we utilized network pharmacology to systematically investigate the bioactive components and targets of JOEI, identify common targets in NSCLC, and understand and evaluate the underlying mechanism of JOEI in the treatment of NSCLC through expression level, correlation, enrichment, Cox, survival and molecular docking analyses. The results indicated that five compounds of JOEI interact with five pivotal targets (LDLR, FABP4, ABCB1, PTGS2, and SDC4) that might be strongly correlated with the JOEI-mediated treatment of NSCLC.

Results

The expression level analysis demonstrated that NSCLC tissues exhibit low expression of FABP4, ABCB1, LDLR and PTGS2 and high SDC4 expression. According to the correlation analysis, a decrease in FABP4 expression was strongly correlated with decreases in LDLR and ABCB1, and a decrease in LDLR was strongly correlated with decreased PTGS2 and increased in SDC4 expression. Cox and survival analyses showed that the survival rate of the high-risk group was significantly lower than that of the low-risk group (p = 0.00388). In the survival analysis, the area under the curve (AUC) showed that the pivotal gene model exhibited the best predictive capacity over 4 years (AUC = 0.613). Moreover, the molecular docking analysis indicated that LDLR, FABP4, ABCB1, PTGS2 and SDC4 exhibit good binding activity with the corresponding compounds.

Conclusion

In conclusion, this study predicted and verified that the mechanism of JOEI against NSCLC involves multiple targets and signaling pathways. Furthermore, this study provides candidate targets for the treatment of NSCLC, lays a good foundation for further experimental research and promotes the reasonable application of JOEI in clinical treatment.

Mapping Pharmacological Network of Multi-Targeting Litchi Ingredients in Cancer Therapeutics

Considerable pharmacological studies have demonstrated that the extracts and ingredients from different parts (seeds, peels, pulps, and flowers) of Litchi exhibited anticancer effects by affecting the proliferation, apoptosis, autophagy, metastasis, chemotherapy and radiotherapy sensitivity, stemness, metabolism, angiogenesis, and immunity via multiple targeting. However, there is no systematical analysis on the interaction network of “multiple ingredients-multiple targets-multiple pathways” anticancer effects of Litchi. In this study, we summarized the confirmed anticancer ingredients and molecular targets of Litchi based on published articles and applied network pharmacology approach to explore the complex mechanisms underlying these effects from a perspective of system biology. The top ingredients, top targets, and top pathways of each anticancer function were identified using network pharmacology approach. Further intersecting analyses showed that Epigallocatechin gallate (EGCG), Gallic acid, Kaempferol, Luteolin, and Betulinic acid were the top ingredients which might be the key ingredients exerting anticancer function of Litchi, while BAX, BCL2, CASP3, and AKT1 were the top targets which might be the main targets underling the anticancer mechanisms of these top ingredients. These results provided references for further understanding and exploration of Litchi as therapeutics in cancer as well as the application of “Component Formula” based on Litchi’s effective ingredients.

In-vitro antibacterial, antioxidant potentials and cytotoxic activity of the leaves of Tridax procumbens

The present study explored the phytochemicals, antibacterial, antioxidant and cytotoxic effect of Tridax procumbens leaves. The leaves were dried and extracted with various organic solvents. The leaves contained the phytochemicals such as alkaloids, carbohydrates, polyphenols and tannins respectively. Antimicrobial potentials of the extracts were determined by performing the disc diffusion techniques. Results revealed that different organic solvents extracts namely methanol, ethanol and ethyl acetate extracts documented comparatively good activity against the studied microbial strains. The methanol extract of leaves of T. procumbens showed combatively better antioxidant potential. The tested plant leaf extract showed high activity against human lung cancer cells than breast cancer cell lines. 250 µg/ml plants extract showed 84 ± 2.8% toxicity against human lung cancer cells.

SIX4 acts as a master regulator of oncogenes that promotes tumorigenesis in non-small-cell lung cancer cells

A number of homeobox genes are implicated in the malignancy of various cancers. Here, we investigated the role of the homeobox gene SIX4 in non-small-cell lung cancer (NSCLC). The sine oculis homeobox (SIX4) gene was found to be highly expressed at both mRNA and protein levels in NSCLC tumor tissues as compared with matching normal counterparts. In this study, the SIX4 gene of two human NSCLC cell lines (A549 and PC9) was overexpressed or silenced using the lentiviral system. We evaluated the malignancy-associated phenotype of transfected cells, which demonstrated that exogenous expression of the SIX4 gene greatly enhanced the proliferation, migration, and invasion of NSCLC cells. The opposite was true in the SIX4-silenced cells. Transcriptomic profiling analysis revealed that the SIX4 gene modulated the expression of hundreds of downstream target genes in a cell context-dependent manner. Most notably, the SIX4 gene controls the expression of crucial genes with evidently oncogenic function. We conclude that SIX4 plays an oncogenic role and may be potentially utilized as a diagnostic and therapeutic marker for NSCLC.

Reversal of Multidrug Resistance in Cancer by Multi-Functional Flavonoids

Multidrug resistance (MDR) resulting from different defensive mechanisms in cancer is one of the major obstacles of clinical treatment. To circumvent MDR many reversal agents have been developed, but most of them fail in clinical trials due to severely adverse effects. Recently, certain natural products have been reported to overcome MDR, including flavonoids which are abundant in plants, foods, and herbs. The structure of flavonoids can be abbreviated as C6-C3-C6 (C for carbon), and further categorized into flavonoids, iso-flavonoids and neo-flavonoids, according to their structural backbones. Flavonoids possess multiple bioactivities, and a growing body of research has indicated that both flavonoids and iso-flavonoids can either kill or re-sensitize conventional chemotherapeutics to resistant cancer cells. Here, we summarize the research and discuss the underlying mechanisms, concluding that these flavonoids do not function as specific regulators of target proteins, but rather as multi-functional agents that negatively regulate the key factors contributing to MDR.

Apoptosis induced by luteolin in breast cancer: Mechanistic and therapeutic perspectives

BACKGROUND

Breast cancer is worldwide commonly found malignancy in women and effective treatment is regarded as a huge clinical challenge even in the presence of several options. Extensive literature is available that demonstrating polyphenols, the richly introduce phytopharmaceuticals as anticancer agents. Among these polyphenols, resveratrol, silibinin, quercetin, genistein, curcumin reported to have an awesome potential against breast cancer. However, till now no comprehensive survey found about the anticarcinogenic properties of luteolin against breast cancer.

SCOPE AND APPROACH

This review targeted the available literature on luteolin in the treatment of breast cancer, effects in combination with other anticancer drugs with possible mechanisms.

KEY FINDINGS AND CONCLUSION

An outstanding therapeutic potential of luteolin in the treatment of breast cancer has been recorded not just as a chemopreventive and chemotherapeutic agent yet complemented by its synergistic effects with other anticancer therapies such as cyclophosphamide, doxorubicin, and NSAID such as celecoxib, and possible underlying mechanisms. Ideally, this review will open new dimensions for luteolin as an effective and safe therapeutic agent in diminishing breast cancer.

Ameliorative effects of luteolin against endometriosis progression in vitro and in vivo

Endometriosis is a common gynecological disease in reproductive-aged women. Generally, accumulation of backflow and debris of endometrial tissue develops into a lesion outside of the endometrium, inducing severe pelvic pain and infertility in some patients. Hormone therapy and surgery are the main treatments available, but various therapeutic phytochemicals are being reviewed in animal studies or clinical trials for endometriosis patients nowadays. However, the therapeutic effects of luteolin in human endometriosis have not been studied well. Here, we demonstrate that luteolin exerts antiproliferative and apoptotic effects in human VK2/E6E7 and End1/E6E7 and in an animal endometriosis model. Luteolin inhibits cell proliferation through cell cycle arrest and induces apoptosis through DNA fragmentation in VK2/E6E7 and End1/E6E7 cells. Cytosolic calcium levels, ROS production and lipid peroxidation also increased dose-dependently (0, 5, 10 and 20 μM) in the treatment with luteolin. In VK2/E6E7 and End1/E6E7 cells, luteolin decreased ERK1/2, JNK and PI3K/AKT signal proteins while activating P38. In addition, intraperitoneal injection of luteolin in the endometriosis mouse model reduced lesion size compared to vehicle-injected mice. Ccne1, Cdk2 and Cdk4 were significantly down-regulated in the autoimplanted endometriosis lesions of mice intraperitoneally injected with luteolin. Knockdown of CCNE1 mRNA in VK2/E6E7 and End1/E6E7 cells decreased cell viability through inhibition of G0/G1 phase progression and increased apoptosis. Together, our results imply that luteolin suppresses endometriosis development by regulation of the PI3K/AKT and MAPK signal proteins as well as the expression of CCNE1 in vitro and in vivo.

Luteolin inhibits cell cycle progression and induces apoptosis of breast cancer cells through downregulation of human telomerase reverse transcriptase

Luteolin is a flavonoid, which has been extensively investigated due to its antitumor effects; however, the underlying mechanisms of its action remain largely unknown. The present study aimed to investigate the role of luteolin in breast cancer (BC), and explored how luteolin suppresses the growth and induces the apoptosis of BC cells. The MTS assay was used to determine the anticancer activity of luteolin. Colony formation and Transwell assays were performed to evaluate the effects of luteolin on cell growth and invasion. Cell cycle progression and apoptosis were analyzed by flow cytometry. In addition, western blotting was performed to analyze cellular apoptosis and signaling pathways elicited by luteolin. The present study revealed that the proliferation of the BC cell line MDA-MB-231 was effectively suppressed by luteolin in a dose-dependent manner. Additionally, luteolin was revealed to increase apoptotic rates in BC cells. Dose-dependent cell cycle arrest in S phase was observed following treatment with luteolin in MDA-MB-231 cells. Mechanistically, luteolin reduced telomerase levels in a dose-dependent manner. Additionally, luteolin inhibited phosphorylation of the nuclear factor-κB inhibitor α and its target gene c-Myc, to suppress human telomerase reverse transcriptase (hTERT) expression, which encodes the catalytic subunit of telomerase. Collectively, the results of the present study indicated that luteolin may inhibit BC cell growth by targeting hTERT, suggesting that the mechanism of hTERT regulation by luteolin may justify further study regarding its potential as a therapeutic target for BC treatment.

Luteolin sensitizes the antitumor effect of cisplatin in drug-resistant ovarian cancer via induction of apoptosis and inhibition of cell migration and invasion

Luteolin, a polyphenolic flavone, has been demonstrated to exert anti-tumor activity in various cancer types. Cisplatin drug resistance is a major obstacle in the management of ovarian cancer. In the present study, we investigated the chemo-sensitizing effect of luteolin in both cisplatin-resistant ovarian cancer cell line and a mice xenotransplant model. In vitro, CCK-8 assay showed that luteolin inhibited cell proliferation in a dose-dependent manner, and luteolin enhanced anti-proliferation effect of cisplatin on cisplatin-resistant ovarian cancer CAOV3/DDP cells. Flow cytometry revealed that luteolin enhanced cell apoptosis in combination with cisplatin. Western blotting and qRT-PCR assay revealed that luteolin increased cisplatin-induced downregulation of Bcl-2 expression. In addition, wound-healing assay and Matrigel invasion assay showed that luteolin and cisplatin synergistically inhibited migration and invasion of CAOV3/DDP cells. Moreover, in vivo, luteolin enhanced cisplatin-induced reduction of tumor growth as well as induction of apoptosis. We suggest that luteolin in combination with cisplatin could potentially be used as a new regimen for the treatment of ovarian cancer.

Mechanistic evaluation of phytochemicals in breast cancer remedy: current understanding and future perspectives

Breast cancer is one of the most commonly diagnosed cancers around the globe and accounts for a large proportion of fatalities in women. Despite the advancement in therapeutic and diagnostic procedures, breast cancer still represents a major challenge. Current anti-breast cancer approaches include surgical removal, radiotherapy, hormonal therapy and the use of various chemotherapeutic drugs. However, drug resistance, associated serious adverse effects, metastasis and recurrence complications still need to be resolved which demand safe and alternative strategies. In this scenario, phytochemicals have recently gained huge attention due to their safety profile and cost-effectiveness. These phytochemicals modulate various genes, gene products and signalling pathways, thereby inhibiting breast cancer cell proliferation, invasion, angiogenesis and metastasis and inducing apoptosis. Moreover, they also target breast cancer stem cells and overcome drug resistance problems in breast carcinomas. Phytochemicals as adjuvants with chemotherapeutic drugs have greatly enhanced their therapeutic efficacy. This review focuses on the recently recognized molecular mechanisms underlying breast cancer chemoprevention with the use of phytochemicals such as curcumin, resveratrol, silibinin, genistein, epigallocatechin gallate, secoisolariciresinol, thymoquinone, kaempferol, quercetin, parthenolide, sulforaphane, ginsenosides, naringenin, isoliquiritigenin, luteolin, benzyl isothiocyanate, α-mangostin, 3,3'-diindolylmethane, pterostilbene, vinca alkaloids and apigenin.

Mechanism of metastasis suppression by luteolin in breast cancer

Metastatic breast cancer is typically an extremely aggressive cancer with poor prognosis. Metastasis requires the orchestration of homeostatic factors and cellular programs, many of which are potential therapeutic targets. Luteolin (2-[3,4-dihydroxyphenyl]-5,7-dihydroxy-4-chromenone), is a naturally occurring flavonoid found in fruits and vegetables that exhibits many anticancer properties. Luteolin obstructs metastasis through both direct and indirect mechanisms. For instance, luteolin may suppress breast cancer invasion by acting as an antiangiogenic therapeutic inhibiting VEGF production and its receptor’s activity. Furthermore, luteolin decreases epithelial–mesenchymal transition markers and metastatic proclivity. Luteolin also acts as an antiproliferative by suppressing receptor tyrosine-kinase activity and apoptosis, both of which could prevent incipient colonization of breast cancer. Many of these antimetastatic characteristics accredited to luteolin are likely functionally related. For instance, the PI3K/Akt pathway, which is impeded by luteolin, has several downstream programs involved in increased proliferation, survival, and metastatic potential in breast cancer. In this review, luteolin’s ability to ameliorate breast cancer is summarized. The paper also offers insight into the molecular mechanisms by which luteolin may suppress breast cancer metastasis.

NRF2 Regulates HER1 Signaling Pathway to Modulate the Sensitivity of Ovarian Cancer Cells to Lapatinib and Erlotinib

NF-E2-related factor 2 (NRF2) regulates the transcription of a battery of metabolic and cytoprotective genes. NRF2 and epidermal growth factor receptors (EGFRs/HERs) are regulators of cellular proliferation and determinants of cancer initiation and progression. NRF2 and HERs confer cancers with resistance to several therapeutic agents. Nevertheless, there is limited understanding of the regulation of HER expression and activation and the link between NRF2 and HER signalling pathways. We show that NRF2 regulates both basal and inducible expression of HER1, as treatment of ovarian cancer cells (PEO1, OVCAR3, and SKOV3) with NRF2 activator tBHQ inducing HER1, while inhibition of NRF2 by siRNA knockdown or with retinoid represses HER1. Furthermore, treatment of cells with tBHQ increased total and phosphorylated NRF2, HER1, and AKT levels and compromised the cytotoxic effect of lapatinib or erlotinib. Treatment with siRNA or retinoid antagonised the effect of tBHQ on NRF2 and HER1 levels and enhanced the sensitivity of ovarian cancer cells to lapatinib or erlotinib. Pharmacological or genetic inhibition of NRF2 and/or treatment with lapatinib or erlotinib elevated cellular ROS and depleted glutathione. This extends the understanding of NRF2 and its regulation of HER family receptors and opens a strategic target for improving cancer therapy.

Translational opportunities for broad-spectrum natural phytochemicals and targeted agent combinations in breast cancer

Breast cancer (BC) prevention and therapy in the context of life-style risk factors and biological drivers is a major focus of developmental therapeutics in oncology. Obesity, alcohol, chronic estrogen signaling and smoking have distinct BC precipitating and facilitating effects that may act alone or in combination. A spectrum of signaling events including enhanced oxidative stress and changes in estrogen-receptor (ER)-dependent and -independent signaling drive the progression of BC. Breast tumors modulate ERα/ERβ ratio, upregulate proliferative pathways driven by ERα and HER2 with a parallel loss and/or downregulation of tumor suppressors such as TP53 and PTEN which together impact the efficacy of therapeutic strategies and frequently lead to emergence of drug resistance. Natural phytochemicals modulate oxidative stress, leptin, integrin, HER2, MAPK, ERK, Wnt/β-catenin and NFκB signaling along with regulating ERα and ERβ, thereby presenting unique opportunities for both primary and combinatorial interventions in BC. In this regard, this article focuses on critical analyses of the evidence from multiple studies on the efficacy of natural phytochemicals in BC. In addition, areas in which the combinations of such effective natural phytochemicals with approved and/or developing anticancer agents can be translationally beneficial are discussed to derive evidence-based inference for addressing challenges in BC control and therapy.

Anticancer effect of luteolin is mediated by downregulation of TAM receptor tyrosine kinases, but not interleukin-8, in non-small cell lung cancer cells

TAM receptor tyrosine kinases (RTKs), Tyro3, Axl and MerTK, transduce diverse signals responsible for cell survival, growth, proliferation and anti-apoptosis. In the present study, we demonstrated the effect of luteolin, a flavonoid with antioxidant, anti-inflammatory and anticancer activities, on the expression and activation of TAM RTKs and the association with its cytotoxicity in non-small cell lung cancer (NSCLC) cells. We observed the cytotoxic effect of luteolin in parental A549 and H460 cells as well as in cisplatin-resistant A549/CisR and H460/CisR cells. Exposure of these cells to luteolin also resulted in a dose‑dependent decrease in clonogenic ability. Next, luteolin was found to decrease the protein levels of all three TAM RTKs in the A549 and A549/CisR cells in a dose‑dependent manner. In a similar manner, in H460 and H460/CisR cells, the protein levels of Axl and Tyro3 were decreased following luteolin treatment. In addition, Axl promoter activity was decreased by luteolin, indicating that luteolin suppresses Axl expression at the transcriptional level. We next found that luteolin abrogated Axl phosphorylation in response to growth arrest-specific 6 (Gas6), its ligand, implying the inhibitory effect of luteolin on Gas6-induced Axl activation. Ectopic expression of Axl was observed to attenuate the antiproliferative effect of luteolin, while knockdown of the Axl protein level using a gold nanoparticle-assisted gene delivery system increased its cytotoxicity. In contrast to the inhibitory effect of luteolin on the expression of TAM RTKs, interleukin-8 (IL-8) production was not decreased by luteolin in H460 and H460/CisR cells, while IL-8 production/cell was increased. Collectively, our data suggest that TAM RTKs, but not IL-8, are promising therapeutic targets of luteolin to abrogate cell proliferation and to overcome chemoresistance in NSCLC cells.

Luteolin suppresses the metastasis of triple-negative breast cancer by reversing epithelial-to-mesenchymal transition via downregulation of β-catenin expression

The metastasis of breast cancer is associated with dismal prognosis and high mortality due to the lack of effective treatment. Luteolin, a natural flavonoid compound, has been shown to exert antitumor activity in various types of cancers. However, the effects and mechanisms of luteolin on the metastasis of triple-negative breast cancer (TNBC) remain elusive. In the present study, we found that pretreatment of highly metastatic TNBC cell lines with luteolin dose‑dependently inhibited cell migration and invasion, and reversed epithelial-mesenchymal transition (EMT) as determined by altered morphological characteristics, downregulated epithelial markers and upregulated mesenchymal markers, and inhibited EMT-related transcription factors. In an in vivo metastasis experiment using a xenograft model, luteolin markedly inhibited lung metastases of breast cancer and the expression of EMT molecules vimentin and Slug in primary tumor tissues. Notably, luteolin also suppressed the expression of β-catenin mRNA and protein in vitro and in vivo. Furthermore, overexpression of β-catenin by adenoviruses blocked these benefits of luteolin on invasion and metastases of breast cancer. In conclusion, all these results indicated that luteolin effectively suppressed metastases of breast cancer by reversing EMT, which may be mediated by downregulation of β-catenin.

Epithelial-to-Mesenchymal Transition in Paclitaxel-Resistant Ovarian Cancer Cells Is Downregulated by Luteolin

Ovarian cancer (OVCA) is the deadliest of all gynecological cancers which is attributed to late presentation, persistence, and development of chemoresistance. The objectives were to evaluate the association between OVCA paclitaxel-resistance and epithelial-to-mesenchymal transition (EMT) and to determine the capability of luteolin to chemosensitize OVCA cells. X10 and X22 cells were 11.8-25.3-fold and 7.8-8.6-fold resistant to paclitaxel than 1AP cells. X10 and X22 cells exhibited a mesenchymal phenotype, while 1AP has an epithelial characteristics. Furthermore, the expression of the epithelial marker E-cadherin was downregulated, while mesenchymal markers Vimentin and N-cadherin were upregulated in X10 and X22 cells when compared to 1AP cells. Transcription factors Snail, Slug, and Twist1 were upregulated in X10 cells, while Twist1 was highly expressed in X22 cells. Luteolin treatment caused cytotoxicity being most potent to X10 OVCA cells. Treatment of non-cytotoxic dose of luteolin at 15.625 μM chemosensitized X10 and X22 OVCA cells to paclitaxel as evidenced by reduced ED₅₀ values from 11.8 to 0.2 μM and 8.6 to 3.6 μM for X10 and X22 cells, respectively. Moreover, luteolin treatment led to a more epithelial phenotype of X10 and X22 cells and modification of EMT markers indicating reversal of EMT. The mechanism involved is through reduction of phosphorylation of FAK and ERK leading to reduced nuclear translocation of p65. Our results highlight the significance of EMT in OVCA resistance to paclitaxel and warrant the investigation of luteolin as a potential therapeutic agent in chemoresistant OVCA. J. Cell. Physiol. 232: 391-401, 2017. © 2016 Wiley Periodicals, Inc.

Antitumour activity of the novel flavonoid Oncamex in preclinical breast cancer models

Background:

The natural polyphenol myricetin induces cell cycle arrest and apoptosis in preclinical cancer models. We hypothesised that myricetin-derived flavonoids with enhanced redox properties, improved cell uptake and mitochondrial targeting might have increased potential as antitumour agents.

Methods:

We studied the effect of a second-generation flavonoid analogue Oncamex in a panel of seven breast cancer cell lines, applying western blotting, gene expression analysis, fluorescence microscopy and immunohistochemistry of xenograft tissue to investigate its mechanism of action.

Results:

Proliferation assays showed that Oncamex treatment for 8 h reduced cell viability and induced cytotoxicity and apoptosis, concomitant with increased caspase activation. Microarray analysis showed that Oncamex was associated with changes in the expression of genes controlling cell cycle and apoptosis. Fluorescence microscopy showed the compound's mitochondrial targeting and reactive oxygen species-modulating properties, inducing superoxide production at concentrations associated with antiproliferative effects. A preliminary in vivo study in mice implanted with the MDA-MB-231 breast cancer xenograft showed that Oncamex inhibited tumour growth, reducing tissue viability and Ki-67 proliferation, with no signs of untoward effects on the animals.

Conclusions:

Oncamex is a novel flavonoid capable of specific mitochondrial delivery and redox modulation. It has shown antitumour activity in preclinical models of breast cancer, supporting the potential of this prototypic candidate for its continued development as an anticancer agent.

Anticancer potential of selected Fallopia Adans species

The aim of the present study was to determine the anticancer potential of three species belonging to the Fallopia genus (Polygonaceae): Fallopia convolvulus (F. convolvulus, Fallopia dumetorum (F. dumetorum) and Fallopia aubertii (F. aubertii). For this purpose, crude extracts were obtained and characterized for their phenolic and flavonoid total content and examined for their anticancer activity on three tumor cell lines: breast cancer (MCF7), colon carcinoma (Caco-2) and cervical cancer (HeLa) cells. The cytotoxic potential of the three species was assessed by MTT assay, cell cycle analysis and by the evaluation of mitochondrial membrane potential (MMP). The acute toxicity of the extracts was evaluated using one in vitro cell model (Vero cells, an African Green monkey kidney cell line) and two invertebrate in vivo models (Daphnia magna and Artemia salina). The highest total phenolic and flavonoid content was found in the F. aubertii flower extracts. The cytotoxic effects of the extracts from F. aubertii and F. convolvulus on all three cell lines were examined at concentrations ranging from 3 to 300 µg/ml. G2/M cell cycle arrest was induced by all the extracts, and a significant increase in the subG1 cell population was observed. The hydroethanolic extract from the flowers of F. aubertii induced cell apoptosis more rapidly than the other extracts. The MMP indicates the involvement of the mitochondria in the induction of apoptosis. A positive correlation between the total phenolic content of the extracts and the IC50 values against the HeLa cells was also noted. None of the extracts exhibited significantly toxic effects. Considering the antitumor potential of F. aubertii and F. convolvulus, these two species may represent a good source of plant extracts with anticancer properties.

Involvement of enhancer of zeste homolog 2 in cisplatin-resistance in ovarian cancer cells by interacting with several genes

In the present study, gene expression profiles of cisplatin-sensitive ovarian cancer (OC) cells were compared with those of cisplatin-resistant OC cells to identify key genes and pathways contributing to cisplatin resistance in ovarian cancer cells. The GSE15372 gene expression data set was downloaded from Gene Expression Omnibus, and included five biological replicates of cisplatin-sensitive OC cells and five biological replicates of cisplatin-resistant OC cells. Differentially expressed genes (DEGs) were screened using the limma package in R, based on the cut-off values of P<0.05 and |log2 (fold change)|>1. Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis and Gene Ontology enrichment analysis were performed on the DEGs using the Database for Annotation, Visualization and Integration Discovery. The protein-protein interaction (PPI) network was constructed for the DEGs using STRING, and sub-networks were analyzed by Clustering with Overlapping Neighborhood Expansion. A total of 556 DEGs were identified in the cisplatin-sensitive OC cells, of which 246 were upregulated and 310 were downregulated. Functional enrichment analysis revealed metabolism-associated pathways, DNA replication and cell cycle were significantly enriched in the downregulated genes, while cell growth and differentiation, response to stimulus, and apoptosis were significantly enriched in the upregulated genes. A PPI network, including 342 nodes was constructed for the DEGs and four subnetworks were extracted from the entire network. A total of 34 DEGs interacting with enhancer of zeste homolog 2 (EZH2) were identified, which were associated with DNA replication, pyrimidine metabolism and cell cycle. In conclusion, a number of key genes and pathways associated with the cisplatin-resistance of OC were revealed, particularly EZH2. These findings assist in the development of therapy for OC.

Cyclopia extracts act as ERα antagonists and ERβ agonists, in vitro and in vivo

Hormone replacement therapy associated risks, and the concomitant reluctance of usage, has instigated the search for new generations of estrogen analogues that would maintain estrogen benefits without associated risks. Furthermore, if these analogues display chemo-preventative properties in breast and endometrial tissues it would be of great value. Both the selective estrogen receptor modulators as well as the selective estrogen receptor subtype modulators have been proposed as estrogen analogues with improved risk profiles. Phytoestrogen containing extracts of Cyclopia, an indigenous South African fynbos plant used to prepare Honeybush tea may serve as a source of new estrogen analogues. In this study three extracts, P104, SM6Met, and cup-of-tea, from two species of Cyclopia, C. genistoides and C. subternata, were evaluated for ER subtype specific agonism and antagonism both in transactivation and transrepression. For transactivation, the Cyclopia extracts displayed ERα antagonism and ERβ agonism when ER subtypes were expressed separately, however, when co-expressed only agonism was uniformly observed. In contrast, for transrepression, this uniform behavior was lost, with some extracts (P104) displaying uniform agonism, while others (SM6Met) displayed antagonism when subtypes were expressed separately and agonism when co-expressed. In addition, breast cancer cell proliferation assays indicate that extracts antagonize cell proliferation in the presence of estrogen at lower concentrations than that required for proliferation. Furthermore, lack of uterine growth and delayed vaginal opening in an immature rat uterotrophic model validates the ERα antagonism of extracts observed in vitro and supports the potential of the Cyclopia extracts as a source of estrogen analogues with a reduced risk profile.