Plant-derived flavone Apigenin: The small-molecule with promising activity against therapeutically resistant prostate cancer

Progress in discovery and development of natural inhibitors of histone deacetylases (HDACs) as anti-cancer agents

The study of epigenetic translational modifications had drawn great interest for the last few decades. These processes play a vital role in many diseases and cancer is one of them. Histone acetyltransferase (HAT) and histone deacetylases (HDACs) are key enzymes involved in the acetylation and deacetylation of histones and ultimately in post-translational modifications. Cancer frequently exhibits epigenetic changes, particularly disruption in the expression and activity of HDACs. It includes the capacity to regulate proliferative signalling, circumvent growth inhibitors, escape cell death, enable replicative immortality, promote angiogenesis, stimulate invasion and metastasis, prevent immunological destruction, and genomic instability. The majority of tumours develop and spread as a result of HDAC dysregulation. As a result, HDAC inhibitors (HDACis) were developed, and they today stand as a very promising therapeutic approach. One of the most well-known and efficient therapies for practically all cancer types is chemotherapy. However, the efficiency and safety of treatment are constrained by higher toxicity. The same has been observed with the synthetic HDACi. Natural products, owing to many advantages over synthetic compounds for cancer treatment have always been a choice for therapy. Hence, naturally available molecules are of particular interest for HDAC inhibition and HDAC has drawn the attention of the research fraternity due to their potential to offer a diverse array of chemical structures and bioactive compounds. This diversity opens up new avenues for exploring less toxic HDAC inhibitors to reduce side effects associated with conventional synthetic inhibitors. The review presents comprehensive details on natural product HDACi, their mechanism of action and their biological effects. Moreover, this review provides a brief discussion on the structure activity relationship of selected natural HDAC inhibitors and their analogues which can guide future research to discover selective, more potent HDACi with minimal toxicity.

The Role of Histone Deacetylases in NLRP3 Inflammasomesmediated Epilepsy

Epilepsy is one of the most common brain disorders that not only causes death worldwide, but also affects the daily lives of patients. Previous studies have revealed that inflammation plays an important role in the pathophysiology of epilepsy. Activation of inflammasomes can promote neuroinflammation by boosting the maturation of caspase-1 and the secretion of various inflammatory effectors, including chemokines, interleukins, and tumor necrosis factors. With the in-depth research on the mechanism of inflammasomes in the development of epilepsy, it has been discovered that NLRP3 inflammasomes may induce epilepsy by mediating neuronal inflammatory injury, neuronal loss and blood-brain barrier dysfunction. Therefore, blocking the activation of the NLRP3 inflammasomes may be a new epilepsy treatment strategy. However, the drugs that specifically block NLRP3 inflammasomes assembly has not been approved for clinical use. In this review, the mechanism of how HDACs, an inflammatory regulator, regulates the activation of NLRP3 inflammasome is summarized. It helps to explore the mechanism of the HDAC inhibitors inhibiting brain inflammatory damage so as to provide a potential therapeutic strategy for controlling the development of epilepsy.

Molecular Insight into Prostate Cancer: Preventive Role of Selective Bioactive Molecules

Prostate cancer (CaP) is one of the most prevalent male malignancies, accounting for a considerable number of annual mortalities. However, the prompt identification of early-stage CaP often faces delays due to diverse factors, including socioeconomic inequalities. The androgen receptor (AR), in conjunction with various other signaling pathways, exerts a central influence on the genesis, progression, and metastasis of CaP, with androgen deprivation therapy (ADT) serving as the primary therapeutic strategy. Therapeutic modalities encompassing surgery, chemotherapy, hormonal intervention, and radiotherapy have been formulated for addressing early and metastatic CaP. Nonetheless, the heterogeneous tumor microenvironment frequently triggers the activation of signaling pathways, culminating in the emergence of chemoresistance, an aspect to which cancer stem cells (CSCs) notably contribute. Phytochemicals emerge as reservoirs of bioactive agents conferring manifold advantages against human morbidity. Several of these phytochemicals demonstrate potential chemoprotective and chemosensitizing properties against CaP, with selectivity exhibited towards malignant cells while sparing their normal counterparts. In this context, the present review aims to elucidate the intricate molecular underpinnings associated with metastatic CaP development and the acquisition of chemoresistance. Moreover, the contributions of phytochemicals to ameliorating CaP initiation, progression, and chemoresistance are also discussed.

Protective Effects of Naringenin and Apigenin in Ameliorating Skin Damage via Mediating the Nrf2 and NF-κB Pathways in Mice

Naringenin and apigenin are common flavonoids derived from edible plants with the potential to alleviate inflammation and improve skin antioxidation. This study aimed to evaluate the effects of naringenin and apigenin on oleic acid-induced skin damage in mice and compare their underlying mechanisms of action. Triglycerides and non-esterified fatty acids were significantly decreased by naringenin and apigenin, while apigenin intervention resulted in a better recovery of skin lesions. Naringenin and apigenin improved the antioxidative abilities of the skin by increasing catalase and total antioxidant capacity levels and decreasing malondialdehyde and lipid peroxide levels. The release of skin proinflammatory cytokines, such as interleukin (IL)-6, IL-1β, and tumor necrosis factor α, was inhibited after naringenin and apigenin pretreatments, but naringenin only promoted the excretion of IL-10. Additionally, naringenin and apigenin regulated antioxidant defense and inflammatory response by activating nuclear factor erythroid-2 related factor 2-dependent mechanisms and suppressing the expression of nuclear factor-kappa B. In summary, naringenin and apigenin are prospective ingredients that contribute to the amelioration of skin damage by activating anti-inflammatory and antioxidative responses.

Apigenin alleviates oxidative stress-induced myocardial injury by regulating SIRT1 signaling pathway

Apigenin is a natural flavonoid which is widely found in vegetables and fruits. However, the mechanism of apigenin in oxidative stress-induced myocardial injury has not been fully elucidated. We established an isoproterenol (Iso)-induced myocardial injury mouse model and a hypoxia/reoxygenation (H/R)-induced H9c2 cell injury model, followed by pretreatment with apigenin to explore its protective effects. Apigenin can significantly alleviate isoproterenol-induced oxidative stress, cell apoptosis and myocardial remodeling in vivo. Apigenin pretreatment can also significantly improve cardiomyocyte morphology, decrease H/R induced oxidative stress, and attenuate cell apoptosis and inflammation in vitro. Further mechanism study revealed that apigenin treatment reversed isoprenaline and H/R-induced decrease of Sirtuin1 (SIRT1). Molecular docking results proved that apigenin can form hydrogen bond with 230 Glu, a key site of SIRT1 activation, indicating that apigenin is an agonist of SIRT1. Moreover, SIRT1 knockdown by siRNA significantly reversed the protective effect of apigenin in H/R-induced myocardial injury. In conclusion, apigenin protects cardiomyocyte function from oxidative stress-induced myocardial injury by modulating SIRT1 signaling pathway, which provides a new potential therapeutic natural compound for the clinical treatment of cardiovascular diseases.

Effectiveness of Apigenin, Resveratrol, and Curcumin as Adjuvant Nutraceuticals for Calvarial Bone Defect Healing: An In Vitro and Histological Study on Rats

Bone healing is a major clinical issue, especially in bone defects of critical dimensions. Some studies have reported in vivo positive effects on bone healing by some bioactive compounds, such as the phenolic derivatives found in vegetables and plants, such as resveratrol, curcumin, and apigenin. The aim of this work was (1) to analyze in vitro in human dental pulp stem cells the effects of these three natural compounds on the gene expression of related genes downstream to RUNX2 and SMAD5, key factor transcriptions associated with osteoblast differentiation, in order to better understand the positive effects that can occur in vivo in bone healing, and (2) to evaluate in vivo the effects on bone healing of critical-size defects in the calvaria in rats of these three nutraceuticals tested in parallel and for the first time administered by the gastric route. Upregulation of the RUNX2, SMAD5, COLL1, COLL4, and COLL5 genes in the presence of apigenin, curcumin, and resveratrol was detected. In vivo, apigenin induced more consistent significant bone healing in critical-size defects in rat calvaria compared to the other study groups. The study findings encourage a possible therapeutic supplementation with nutraceuticals during the bone regeneration process.

Apigenin in cancer therapy: Prevention of genomic instability and anticancer mechanisms

The incidence of cancer has been growing worldwide. Better survival rates following the administration of novel drugs and new combination therapies may concomitantly cause concern regarding the long-term adverse effects of cancer therapy, for example, second primary malignancies. Moreover, overcoming tumour resistance to anticancer agents has been long considered as a critical challenge in cancer research. Some low toxic adjuvants such as herb-derived molecules may be of interest for chemoprevention and overcoming the resistance of malignancies to cancer therapy. Apigenin is a plant-derived molecule with attractive properties for chemoprevention, for instance, promising anti-tumour effects, which may make it a desirable adjuvant to reduce genomic instability and the risks of second malignancies among normal tissues. Moreover, it may improve the efficiency of anticancer modalities. This paper aims to review various effects of apigenin in both normal tissues and malignancies. In addition, we explain how apigenin may have the ability to protect usual cells against the genotoxic repercussions following radiotherapy and chemotherapy. Furthermore, the inhibitory effects of apigenin on tumours will be discussed.

Apigenin impedes cell cycle progression at G2 phase in prostate cancer cells

As a natural flavone, apigenin is abundantly present in vegetables, fruits, oregano, tea, chamomile, wheat sprout and is regarded as a major component of the Mediterranean diet. Apigenin is known to inhibit proliferation in different cancer cell lines by inducing G₂/M arrest, but it is unclear whether this action is predominantly imposed on G₂ or M phases. In this study, we demonstrate that apigenin arrests prostate cancer cells at G₂ phase by flow cytometric analysis of prostate cancer cells co-stained for phospho-Histone H3 and DNA. Concurrently, apigenin also reduces the mRNA and protein levels of the key regulators that govern G₂-M transition. Further analysis using chromatin immunoprecipitation (ChIP) confirmed the diminished transcriptional activities of the genes coding for these regulators. Unravelling the inhibitory effect of apigenin on G₂-M transition in cancer cells provides the mechanistic understanding of its action and supports the potential for apigenin as an anti-cancer agent.

Apigenin inhibits renal cell carcinoma cell proliferation through G2/M phase cell cycle arrest

Apigenin is a flavonoid widely presented in fruits and vegetables, and is known to possess anti‑inflammatory, antioxidant, and anticancer properties. The present study was designed to investigate the effects of apigenin on renal cell carcinoma (RCC) cells. These effects on cell growth were evaluated using a cell counting kit, while cell cycle distribution was investigated by flow cytometry following propidium iodide DNA staining. The human RCC cell lines, Caki‑1, ACHN, and NC65, were each treated with 1‑100 µM apigenin for 24 h, which resulted in concentration‑dependent cell growth inhibition, with the effects confirmed by trypan blue staining. Furthermore, even when the apigenin treatment period was shortened to 3 h, the same cytostatic effect on RCC cells was noted. Similarly, a concentration‑dependent cell growth inhibitory effect was also observed in primary RCC cells, as apigenin induced G2/M phase cell cycle arrest and reduced the expression levels of cyclin A, B1, D3, and E in RCC cells in both dose‑ and time‑dependent manners. These findings suggest the possibility of the use of apigenin as a novel therapeutic strategy for treatment of RCC due to its anticancer activity and ability to function as a cell cycle modulating agent.

Comprehensive review on ethnobotanical uses, phytochemistry, biological potential and toxicology of Parthenium hysterophorus L.: A journey from noxious weed to a therapeutic medicinal plant

ETHNO-PHARMACOLOGICAL RELEVANCE

Parthenium hysterophorus L. is a noxious weed and a species of flowering plant in the Asteraceae family. It is regarded as the seventh most deadly weed in the world: harmful to both humans and livestock. It is widely known as Congress Grass or Feverfew. Despite its pitfalls, P. hysterophorus bestows medicinal effects. Although prolific in nature and difficult to control, many novel applications of this controversial herb have been discovered as an approach to manage the weed.

AIM

The current review aims to compile all the ethnobotanical, phytochemistry, biological activities and utilities, clinical studies and toxicity data available on P. hysterophorus and its major chemical constituent parthenin.

MATERIALS AND METHODS

Extensive literature surveyed Google search, Google scholar, Wiley online library, Elsevier, Springer, Science direct, American Chemical Society, Royal Society of Chemistry and Research Gate.

RESULT

According to the study, P. hysterophorus is utilized as a traditional medicine throughout Central America and the Caribbean. It can be used to treat skin infections, dermatitis, amoebic dysentery, and as an analgesic in the treatment of muscular rheumatism. The extracts obtained from P. hysterophorus have anti-inflammatory, antioxidant, larvicidal, anti-microbial, insecticidal, hypoglycaemic and anti-cancer activity.

CONCLUSION

The earlier investigations confirmed that P. hysterophorus has numerous traditional and biological applications. However, the scientific data are limited in clinical and toxicological studies. Therefore, further research is required on clinical and toxicological aspects to understand the complete potential and effects of P. hysterophorus.

In Vitro Evaluation of Antioxidant and Anticancer Activity of Lemongrass (Cymbopogon citratus (D.C.) Stapf)

Cancer is considered a multifactorial disease and its development could be associated with several factors, for example, rotenone exposition. Unfortunately, many cancers are resistant to chemotherapy, as cervical cancer. Regarding this, lemongrass is a remarkable natural product that presents antioxidant and anticancer activities, which could show therapeutic action against rotenone and cervical cancer. Thus, this study aimed to investigate the antioxidant and anticancer action of lemongrass. An in vitro study was conducted using VERO (kidney cells) and SiHa cell lines (cervical cancer cells). VERO cells were exposed to rotenone and lemongrass extract for 24 and 72 h. While SiHa cells were exposed to lemongrass isolated and associated to chemotherapy, 5-fluorouracil, during 24 and 48 h. After, levels of viability, proliferation, and oxidative metabolism were determined. The results showed that lemongrass presents antioxidant activity on VERO cells by increasing cell viability and proliferation and decreasing oxidative stress caused by rotenone. Moreover, lemongrass showed anticancer activity by decreasing cell viability and increasing oxidative stress parameters on SiHa. Besides, lemongrass had no alteration in the chemotherapy activity. Therefore, this study revealed that lemongrass presents antioxidant and anticancer activity since it can protect against the cytotoxicity of rotenone and reduce the cell viability of cervical cancer.

Delineating binding potential, stability of Sulforaphane-N-acetyl-cysteine in the active site of histone deacetylase 2 and testing its cytotoxicity against distinct cancer lines through stringent molecular dynamics, DFT and cell-based assays

Histone deacetylase 2 (HDAC2), an isozyme of Class I HDACs has potent imputations in actuating neurodegenerative signaling. Currently, there are sizeable therapeutic disquiets with the use of synthetic histone deacetylase inhibitors in disease management. This strongly suggests the unfulfilled medical necessity of plant substitutes for therapeutic intervention. Sulforaphane-N-acetyl-cysteine (SFN-N-acetylcysteine or SFN-NAC), a sulforaphane metabolite has shown significantly worthier activity against HDACs under in vitro conditions. However, the atomistic studies of SFN-NAC against HDAC2 are currently lacking. Thus, the present study employed a hybrid strategy including extra-precision (XP) grid-based flexible molecular docking, molecular mechanics generalized born surface area (MM-GBSA), e-Pharmacophores method, and molecular dynamics simulation for exploring the binding strengh, mode of interaction, e-Pharmacophoric features, and stability of SFN-NAC towards HDAC2. Further, the globally acknowledged density functional theory (DFT) study was performed on SFN-NAC and entinostat individually in complex state with HDAC2. Apart from this, these inhibitors were tested against three distinct cancer cell models and one transformed cell line for cytotoxic activity. Moreover, double mutant of HDAC2 was generated and the binding orientation and interaction of SFN-NAC was scrutinized in this state. On the whole, this study unbosomed and explained the comparatively higher binding affinity of entinostat for HDAC2 and its wide spectrum cytotoxicity than SFN-NAC.

Apigenin inhibits the growth of colorectal cancer through down-regulation of E2F1/3 by miRNA-215-5p

BACKGROUND

Apigenin (API) is a naturally occurring plant-derived flavone, which is abundantly present in common fruits and vegetables, and shows little or no toxicity of daily diet. The treatment of colorectal cancer is limited by high recurrence rate and multidrug resistance.

PURPOSE

The purpose of this study was to explore the potential therapeutic effect and possible mechanisms of API on colorectal cancer cells.

METHODS

Cell proliferation and apoptosis of human colon cancer cell line HCT116 was assessed after API treatment. A comprehensive transcriptome profile of API-treated HCT116 cells was acquired by high-throughput sequencing. The regulation of miRNA215-5p and E2F1/3 were identified by bioinformatics analyses. An inhibitor of miRNA215-5p, inhibitor 215, was applied to confirm the role of this microRNA played in the anti-cancer effect of API. Luciferase reporter gene assay was performed to identify targeting relationship between miRNA215-5p and E2F1/3.

RESULT

API significantly promoted cell apoptosis and anti-proliferation of HCT116 cells in a dose-dependent manner. Bioinformatics analyses identified several altered miRNAs among which the expression of miRNA-215-5p showed markedly increased. Meanwhile, the expression of E2F1 and E2F3 was decreased by API, which was associated with miRNA215-5p. Luciferase reporter gene assay showed miRNA-215-5p could directly bind to 3' UTR of E2F1/3. Inhibition of miRNA-215-5p significantly inhibited apoptosis and cell cycle arrest at G0/G1 phase induced by API.

CONCLUSIONS

The result of this study confirmed the anti-cancer effect of API on human colorectal cancer cells and investigated the underlying mechanism by a comprehensive transcriptome profile of API-treated cells.

The Anticancer Potential of Apigenin Via Immunoregulation

Apigenin is an edible flavonoid widely distributed in natural plants, including most vegetables and fruits. Previous studies have revealed that apigenin possesses multiple biological functions by demonstrating antiinflammatory, anti-oxidative, anti-bacterial, anti-viral, anti-tumor and cardiovascular protective effects. Furthermore, recent progressions have disclosed a novel perspective of the anti-cancer roles of apigenin through its immunoregulatory functions. With the rapid progression of the groundbreaking strategies being developed for cancer immunotherapy, its immunoregulatory roles are being recognized as intriguing features of the multifaceted apigenin. However, the current understanding of this emerging role of apigenin still remains limited. Therefore, in the present review, recent advances on the immunoregulatory properties of apigenin in various diseases with a special focus on neoplasm, are summarized. Clinical strategies of cancer immunotherapy are briefly introduced and findings on apigenin linked to immunoregulatory roles in immunotherapy-associated aspects are brought together. The bioactivity, bioavailability, toxicity and potential of apigenin, to be considered as a therapeutic agent in anti-tumor immunotherapy, is discussed. Disclosed molecular mechanisms underlying the immunoregulatory roles of apigenin in cancer immunotherapy are also summarized. Based on findings from the literature, apigenin has the potential to serve as a prospective adjuvant for anti-cancer immunotherapy and warrants further investigations.

Recent Research on Flavonoids and their Biomedical Applications

Flavonoids, commonly found in various plants, are a class of polyphenolic compounds having a basic structural unit of 2-phenylchromone. Flavonoid compounds have attracted much attention due to their wide biological applications. In order to facilitate further research on the biomedical application of flavonoids, we surveyed the literature published on the use of flavonoids in medicine during the past decade, documented the commonly found structures in natural flavonoids, and summarized their pharmacological activities as well as associated mechanisms of action against a variety of health disorders including chronic inflammation, cancer, cardiovascular complications and hypoglycemia. In this mini-review, we provide suggestions for further research on the biomedical applications of flavonoids.

Flavones as a Privileged Scaffold in Drug Discovery: Current Developments

BACKGROUND

Flavones are one of the main subclasses of flavonoids with diverse pharmacological properties. They have been reported to possess antimalarial, antimicrobial, anti-tuberculosis, anti-allergic, antioxidant, anti-inflammatory activities, among others.

OBJECTIVE

The present review summarizes the recent information on the pharmacological properties of naturally occurring and synthetic flavones.

METHODS

Scientific publications referring to natural and synthetic flavones in relation to their biological activities were hand-searched in databases such as SciFinder, PubMed (National Library of Medicine), Science Direct, Wiley, ACS, SciELO, Springer, among others.

RESULTS

As per the literature, seventy-five natural flavones were predicted as active compounds with reference to their IC50 (<20 µg/mL) in in vitro studies. Also, synthetic flavones were found active against several diseases.

CONCLUSION

As per the literature, flavones are important sources for the potential treatment of multifactorial diseases. However, efforts toward the development of flavone-based therapeutic agents are still needed. The appearance of new catalysts and chemical transformations is expected to provide avenues for the synthesis of unexplored flavones, leading to the discovery of flavones with new properties and biological activities.

Apigenin inhibits growth and migration of fibroblasts by suppressing FAK signaling

The naturally occurring compound apigenin has many biological effects, including anti-inflammatory, antioxidative and anticancer effects. Although hypertrophic scar formation is a common surgical complication, there is still no good treatment for it. In the present study, we examined the effect of apigenin on hypertrophic scar. After isolating fibroblasts from human hypertrophic scars, we assess the effects of apigenin on fibroblast cell survival, apoptosis and migration. The results showed that apigenin dose-dependently inhibited the growth and migration of hypertrophic scar fibroblasts. By inhibiting FAK kinase activity and FAK phosphorylation, apigenin also inhibited activation of the FAK signaling pathway. Apigenin thus appears to inhibit the growth and migration of hypertrophic scar fibroblasts by inhibiting FAK signaling. This suggests apigenin could potentially provide a new option for the treatment of hypertrophic scars.

Flavonoids as Epigenetic Modulators for Prostate Cancer Prevention

Prostate cancer (PCa) is a multifactorial disease with an unclear etiology. Due to its high prevalence, long latency, and slow progression, PCa is an ideal target for chemoprevention strategies. Many research studies have highlighted the positive effects of natural flavonoids on chronic diseases, including PCa. Different classes of dietary flavonoids exhibit anti-oxidative, anti-inflammatory, anti-mutagenic, anti-aging, cardioprotective, anti-viral/bacterial and anti-carcinogenic properties. We overviewed the most recent evidence of the antitumoral effects exerted by dietary flavonoids, with a special focus on their epigenetic action in PCa. Epigenetic alterations have been identified as key initiating events in several kinds of cancer. Many dietary flavonoids have been found to reverse DNA aberrations that promote neoplastic transformation, particularly for PCa. The epigenetic targets of the actions of flavonoids include oncogenes and tumor suppressor genes, indirectly controlled through the regulation of epigenetic enzymes such as DNA methyltransferase (DNMT), histone acetyltransferase (HAT), and histone deacetylase (HDAC). In addition, flavonoids were found capable of restoring miRNA and lncRNA expression that is altered during diseases. The optimization of the use of flavonoids as natural epigenetic modulators for chemoprevention and as a possible treatment of PCa and other kinds of cancers could represent a promising and valid strategy to inhibit carcinogenesis and fight cancer.

Apigenin as an anticancer agent

Apigenin is an edible plant-derived flavonoid that has been reported as an anticancer agent in several experimental and biological studies. It exhibits cell growth arrest and apoptosis in different types of tumors such as breast, lung, liver, skin, blood, colon, prostate, pancreatic, cervical, oral, and stomach, by modulating several signaling pathways. Apigenin induces apoptosis by the activation of extrinsic caspase-dependent pathway by upregulating the mRNA expressions of caspase-3, caspase-8, and TNF-α. It induces intrinsic apoptosis pathway as evidenced by the induction of cytochrome c, Bax, and caspase-3, while caspase-8, TNF-α, and B-cell lymphoma 2 levels remained unchanged in human prostate cancer PC-3 cells. Apigenin treatment leads to significant downregulation of matrix metallopeptidases-2, -9, Snail, and Slug, suppressing invasion. The expressions of NF-κB p105/p50, PI3K, Akt, and the phosphorylation of p-Akt decreases after treatment with apigenin. However, apigenin-mediated treatment significantly reduces pluripotency marker Oct3/4 protein expression which might be associated with the downregulation of PI3K/Akt/NF-κB signaling.

Targeting the SPOCK1-snail/slug axis-mediated epithelial-to-mesenchymal transition by apigenin contributes to repression of prostate cancer metastasis

Background

Prostate cancer (PCa) is considered one of the most prevalent malignancy globally, and metastasis is a major cause of death. Apigenin (API) is a dietary flavonoid which exerts an antimetastatic effect in various cancer types. Sparc/osteonectin, cwcv, and kazal-like domains proteoglycan 1 (SPOCK1) is a crucial modulator of tumor growth and metastasis in cancers. However, the role and underlying regulatory mechanisms of SPOCK1 in the API-mediated antimetastatic effects of PCa remain unclear.

Methods

MTS, colony formation, wound-healing, and transwell assays were conducted to evaluate the effects of API on PCa cell proliferative, migratory, and invasive potentials. In vivo orthotopic bioluminescent xenograft model were employed to determine antitumor activity of API. PCa cells were transfected with either Snail-, Slug-, SPOCK1-overexpressing vector, or small hairpin (sh)SPOCK1 to determine the invasive abilities and expression levels of SPOCK1 and epithelial-to-mesenchymal transition (EMT) biomarkers in response to API treatment. Immunohistochemical (IHC) assays were carried out to evaluate the expression level of SPOCK1 in PCa xenografts and a PCa tissue array. Associations of SPOCK1 expression with clinicopathological features and prognoses of patients with PCa were analyzed by GEO or TCGA RNA-sequencing data.

Results

API significantly suppressed in vitro PCa cell proliferation, migration, and invasion and inhibited in vivo PCa tumor growth and metastasis. Moreover, survival times of animals were also prolonged after API treatment. Mechanistic studies revealed that API treatment resulted in downregulation of SPOCK1, which was accompanied by reduced expressions of mesenchymal markers and subsequent attenuation of invasive abilities of PCa cells. Overexpression of SPOCK1 in PCa xenografts resulted in significant promotion of tumor progression and relieved the anticancer activities induced by API, whereas knockdown of SPOCK1 had opposite effects. In clinical, SPOCK1 levels were higher in tumor tissues compared to non-tumor tissues, which was also significantly correlated with shorter disease-free survival in PCa patients.

Conclusions

Levels of SPOCK1 increase with the progression of human PCa which suggests that SPOCK1 may act as a prognostic marker or therapeutic target for patients with PCa. Suppression of SPOCK1-mediated EMT signaling contributes to the antiproliferative and antimetastatic activities of API in vitro and in vivo.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1247-3) contains supplementary material, which is available to authorized users.

β3-Adrenoreceptor Activity Limits Apigenin Efficacy in Ewing Sarcoma Cells: A Dual Approach to Prevent Cell Survival

Ewing Sarcoma (ES) is an aggressive paediatric tumour where oxidative stress and antioxidants play a central role in cancer therapy response. Inhibiting antioxidants expression, while at the same time elevating intracellular reactive oxygen species (ROS) levels, have been proposed as a valid strategy to overcome ES cancer progression. Flavonoid intake can affect free radical and nutritional status in children receiving cancer treatment, but it is not clear if it can arrest cancer progression. In particular, apigenin may enhance the effect of cytotoxic chemotherapy by inducing cell growth arrest, apoptosis, and by altering the redox state of the cells. Little is known about the use of apigenin in paediatric cancer. Recently, β3-adrenergic receptor (β3-AR) antagonism has been proposed as a possible strategy in cancer therapy for its ability to induce apoptosis by increasing intracellular levels of ROS. In this study we show that apigenin induces cell death in ES cells by modulating apoptosis, but not increasing ROS content. Since ES cells are susceptible to an increased oxidative stress to reduce cell viability, here we demonstrate that administration of β3-ARs antagonist, SR59230A, improves the apigenin effect on cell death, identifying β3-AR as a potential discriminating factor that could address the use of apigenin in ES.

The effect of medicinal plants on multiple drug resistance through autophagy: A review of in vitro studies

Multiple drug resistance (MDR) often occurs after prolonged chemotherapy, leading to refractory tumor and cancer recurrence. Autophagy as a primarily process during starvation or stress has a bipolar nature in cancer. It can cause MDR to become more difficult or make resistant cancer cells more susceptible to chemotherapeutic agents. A number of natural products have been introduced to drug discovery for many years. Some of these compounds have been shown to reverse drug resistance by different regulatory mechanisms. In this review, the focus is on the role of medicinal plants in the MDR phenomenon, primarily through the autophagy process.

Apigenin sensitizes hepatocellular carcinoma cells to doxorubic through regulating miR-520b/ATG7 axis

Chemo-resistance is a serious obstacle for successful treatment of cancer. Apigenin, a dietary flavonoid, has been reported as an anticancer drug in various malignant cancers. This study aimed to investigate the potential chemo-sensitization effect of apigenin in doxorubicin-resistant hepatocellular carcinoma cell line BEL-7402/ADM. We observed that apigenin significantly enhanced doxorubicin sensitivity, induced miR-520b expression and inhibited ATG7-dependent autophagy in BEL-7402/ADM cells. In addition, we also showed that miR-520b mimics increased doxorubicin sensitivity and inhibited ATG7-dependent autophagy. Meanwhile, we indicated that ATG7 was a potential target of miR-520b. Furthermore, APG inhibited the growth of hepatocellar carcinoma xenografts in nude mice by up-regulating miR-520b and inhibiting ATG7. Our finding provides evidence that apigenin sensitizes BEL-7402/ADM cells to doxorubicin through miR-520b/ATG7 pathway, which furtherly supports apigenin as a potential chemo-sensitizer for hepatocellular carcinoma.

Targeting oncogenic transcription factors by polyphenols: A novel approach for cancer therapy

Inflammation is one of the major causative factor of cancer and chronic inflammation is involved in all the major steps of cancer initiation, progression metastasis and drug resistance. The molecular mechanism of inflammation driven cancer is the complex interplay between oncogenic and tumor suppressive transcription factors which include FOXM1, NF-kB, STAT3, Wnt/β- Catenin, HIF-1α, NRF2, androgen and estrogen receptors. Several products derived from natural sources modulate the expression and activity of multiple transcription factors in various tumor models as evident from studies conducted in cell lines, pre-clinical models and clinical samples. Further combination of these natural products along with currently approved cancer therapies added an additional advantage and they considered as promising targets for prevention and treatment of inflammation and cancer. In this review we discuss the application of multi-targeting natural products by analyzing the literature and future directions for their plausible applications in drug discovery.

Flavonoids and Phenolic Acids from Oregano: Occurrence, Biological Activity and Health Benefits

Several herb species classified as oregano have been widely used in folk medicine to alleviate inflammation-related diseases, respiratory and digestive disorders, headaches, rheumatism, diabetes and others. These potential health benefits are partially attributed to the phytochemical compounds in oregano such as flavonoids (FL) and phenolic acids (PA). Flavonoids and phenolic acids are among the most abundant and most studied phytochemicals in oregano species. Epidemiological, in vitro and in vivo experiments have related long-term consumption of dietary FL and PA with a decreased risk of incidence of chronic diseases. The aim of this manuscript is to summarize the latest studies on the identification and distribution of flavonoids and phenolic compounds from oregano species and their potential antioxidant, anti-inflammatory and anti-cancer health benefits.

Apigenin in cancer therapy: anti-cancer effects and mechanisms of action

Apigenin is a common dietary flavonoid that is abundantly present in many fruits, vegetables and Chinese medicinal herbs and serves multiple physiological functions, such as strong anti-inflammatory, antioxidant, antibacterial and antiviral activities and blood pressure reduction. Therefore, apigenin has been used as a traditional medicine for centuries. Recently, apigenin has been widely investigated for its anti-cancer activities and low toxicity. Apigenin was reported to suppress various human cancers in vitro and in vivo by multiple biological effects, such as triggering cell apoptosis and autophagy, inducing cell cycle arrest, suppressing cell migration and invasion, and stimulating an immune response. In this review, we focus on the most recent advances in the anti-cancer effects of apigenin and their underlying mechanisms, and we summarize the signaling pathways modulated by apigenin, including the PI3K/AKT, MAPK/ERK, JAK/STAT, NF-κB and Wnt/β-catenin pathways. We also discuss combinatorial strategies to enhance the anti-cancer effect of apigenin on various cancers and its use as an adjuvant chemotherapeutic agent to overcome cancer drug resistance or to alleviate other adverse effects of chemotherapy. The functions of apigenin against cancer stem cells are also summarized and discussed. These data demonstrate that apigenin is a promising reagent for cancer therapy. Apigenin appears to have the potential to be developed either as a dietary supplement or as an adjuvant chemotherapeutic agent for cancer therapy.

Novel apigenin-loaded sodium hyaluronate nano-assemblies for targeting tumor cells

We aimed to construct a novel nano-assembly carrying apigenin (APG), a hydrophobic drug, and to evaluate its in vitro targeting ability for A549 cells overexpressing CD44 receptors. The apigenin-loaded sodium hyaluronate nano-assemblies (APG/SH-NAs) were assembled by multiple non-covalent interactions between sodium hyaluronate (SH) and APG. The prepared APG/SH-NAs exhibited a small average size and narrow particle size distribution. In addition, satisfactory encapsulation efficiency and drug loading were obtained. The drug release curves indicated that APG/SH-NAs achieved a sustainable drug-release effect due to the presence of hydrophilic materials. The in vitro cytotoxicity of APG/SH-NAs against A549 cells and HepG2 cells was evaluated, and the results indicated that the prepared APG/SH-NA showed higher cytotoxicity compared to apigenin suspensions. When CD44 receptors on the surface of A549 cells were blocked by the addition of excess SH, the cytotoxicity of APG/SH-NA was significantly reduced. However, similar phenomena were not observed in HepG2 cells with relatively low CD44 receptor expression. The resulting APG/SH-NAs could efficiently facilitate the internalization of APG into A549 cells, which might be due to their high affinity for CD44 receptors. Moreover, the apoptotic rate of APG/SH-NAs through receptor-mediated endocytosis mechanism was higher than that of the other groups in A549 cells. Thus, such nano-assemblies were considered to be an effective transport system with excellent affinity for CD44 receptors to allow the SH-mediated targeted delivery of APG.

In Vitro and In Vivo Anti-tumoral Effects of the Flavonoid Apigenin in Malignant Mesothelioma

Malignant mesothelioma (MM) is a tumor arising from mesothelium. MM patients’ survival is poor. The polyphenol 4′,5,7,-trihydroxyflavone Apigenin (API) is a “multifunctional drug”. Several studies have demonstrated API anti-tumoral effects. However, little is known on the in vitro and in vivo anti-tumoral effects of API in MM. Thus, we analyzed the in vitro effects of API on cell proliferation, cell cycle regulation, pro-survival signaling pathways, apoptosis, and autophagy of human and mouse MM cells. We evaluated the in vivo anti-tumor activities of API in mice transplanted with MM #40a cells forming ascites. API inhibited in vitro MM cells survival, increased reactive oxygen species intracellular production and induced DNA damage. API activated apoptosis but not autophagy. API-induced apoptosis was sustained by the increase of Bax/Bcl-2 ratio, increase of p53 expression, activation of both caspase 9 and caspase 8, cleavage of PARP-1, and increase of the percentage of cells in subG1 phase. API treatment affected the phosphorylation of ERK1/2, JNK and p38 MAPKs in a cell-type specific manner, inhibited AKT phosphorylation, decreased c-Jun expression and phosphorylation, and inhibited NF-κB nuclear translocation. Intraperitoneal administration of API increased the median survival of C57BL/6 mice intraperitoneally transplanted with #40a cells and reduced the risk of tumor growth. Our findings may have important implications for the design of MM treatment using API.

Anticancer potential of Trigonella foenum graecum: Cellular and molecular targets

A growing body of evidence supported by numerous studies on tumorigenesis confirms that it is possible to target various hallmarks of cancer. Recent studies have shown that plant-derived molecules may be used in targeting different signaling pathways for cancer drug discovery. The present paper gives an insight into the anticancer potential of fenugreek and lists the existing studies that have been carried out to demonstrate the advantages of the use of fenugreek in cancer treatment and prevention. It also aims at opening up new perspectives in the development of new drugs of natural origins in the future clinical trials. This review article will discuss; (1) the chemical constituents and bioactive compounds of fenugreek; (2) effects on oxidative stress and inflammation; (3) effects on proliferation, apoptosis, and invasion; (4) toxicity of fenugreek; and 5) future directions in cancer drug development. All of the experimental studies discussed in this paper suggest that multiple signaling pathways (hallmarks) are involved in the anticancer activities of fenugreek, but their efficacy is still unclear, which requires further investigation.