Apigenin inhibits renal cell carcinoma cell proliferation

Apigenin: Molecular Mechanisms and Therapeutic Potential against Cancer Spreading

Due to its propensity to metastasize, cancer remains one of the leading causes of death worldwide. Thanks in part to their intrinsic low cytotoxicity, the effects of the flavonoid family in the prevention and treatment of various human cancers, both in vitro and in vivo, have received increasing attention in recent years. It is well documented that Apigenin (4',5,7-trihydroxyflavone), among other flavonoids, is able to modulate key signaling molecules involved in the initiation of cancer cell proliferation, invasion, and metastasis, including JAK/STAT, PI3K/Akt/mTOR, MAPK/ERK, NF-κB, and Wnt/β-catenin pathways, as well as the oncogenic non-coding RNA network. Based on these premises, the aim of this review is to emphasize some of the key events through which Apigenin suppresses cancer proliferation, focusing specifically on its ability to target key molecular pathways involved in angiogenesis, epithelial-to-mesenchymal transition (EMT), maintenance of cancer stem cells (CSCs), cell cycle arrest, and cancer cell death.

Flavonoids derived from medicinal plants as a COVID-19 treatment

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes COVID-19 disease. Through its viral spike (S) protein, the virus enters and infects epithelial cells by utilizing angiotensin-converting enzyme 2 as a host cell's receptor protein. The COVID-19 pandemic had a profound impact on global public health and economies. Although various effective vaccinations and medications are now available to prevent and treat COVID-19, natural compounds derived from medicinal plants, particularly flavonoids, demonstrated therapeutic potential to treat COVID-19 disease. Flavonoids exhibit dual antiviral mechanisms: direct interference with viral invasion and inhibition of replication. Specifically, they target key viral molecules, particularly viral proteases, involved in infection. These compounds showcase significant immunomodulatory and anti-inflammatory properties, effectively inhibiting various inflammatory cytokines. Additionally, emerging evidence supports the potential of flavonoids to mitigate the progression of COVID-19 in individuals with obesity by positively influencing lipid metabolism. This review aims to elucidate the molecular structure of SARS-CoV-2 and the underlying mechanism of action of flavonoids on the virus. This study evaluates the potential anti-SARS-CoV-2 properties exhibited by flavonoid compounds, with a specific interest in their structure and mechanisms of action, as therapeutic applications for the prevention and treatment of COVID-19. Nevertheless, a significant portion of existing knowledge is based on theoretical frameworks and findings derived from in vitro investigations. Further research is required to better assess the effectiveness of flavonoids in combating SARS-CoV-2, with a particular emphasis on in vivo and clinical investigations.

Resources for Human Health from the Plant Kingdom: The Potential Role of the Flavonoid Apigenin in Cancer Counteraction

Apigenin is one of the most widespread flavonoids in the plant kingdom. For centuries, apigenin-containing plant preparations have been used in traditional medicines to treat diseases that have an inflammatory and/or degenerative component. In the 1980s, apigenin was proposed to interfere with the process of carcinogenesis. Since then, more and more evidence has demonstrated its anticancer efficacy, both in vitro and in vivo. Apigenin has been shown to target signaling pathways involved in the development and progression of cancer, such as PI3K/Akt/mTOR, MAPK/ERK, JAK/STAT, NF-κB, and Wnt/β-catenin pathways, and to modulate different hallmarks of cancer, such as cell proliferation, metastasis, apoptosis, invasion, and cell migration. Furthermore, apigenin modulates PD1/PD-L1 expression in cancer/T killer cells and regulates the percentage of T killer and T regulatory cells. Recently, apigenin has been studied for its synergic and additive effects when combined with chemotherapy, minimizing the side effects. Unfortunately, its low bioavailability and high permeability limit its therapeutic applications. Based on micro- and nanoformulations that enhance the physical stability and drug-loading capacity of apigenin and increase the bioavailability of apigenin, novel drug-delivery systems have been investigated to improve its solubility.

Exploring the role of natural bioactive molecules in genitourinary cancers: how far has research progressed?

The primary approaches to treat cancerous diseases include drug treatment, surgical procedures, biotherapy, and radiation therapy. Chemotherapy has been the primary treatment for cancer for a long time, but its main drawback is that it kills cancerous cells along with healthy ones, leading to deadly adverse health effects. However, genitourinary cancer has become a concern in recent years as it is more common in middle-aged people. So, researchers are trying to find possible therapeutic options from natural small molecules due to the many drawbacks associated with chemotherapy and other radiation-based therapies. Plenty of research was conducted regarding genitourinary cancer to determine the promising role of natural small molecules. So, this review focused on natural small molecules along with their potential therapeutic targets in the case of genitourinary cancers such as prostate cancer, renal cancer, bladder cancer, testicular cancer, and so on. Also, this review states some ongoing or completed clinical evidence in this regard.

Immunopotentiation effects of apigenin on NK cell proliferation and killing pancreatic cancer cells

Apigenin is a kind of flavonoid with many beneficial biological effects. It not only has direct cytotoxicity to tumor cells, but also can boost the antitumor effect of immune cells by modulating immune system. The purpose of this study was to investigate the proliferation of NK cells treated with apigenin and its cytotoxicity to pancreatic cancer cells in vitro, and explore its potential molecular mechanism. In this study, the effect of apigenin on NK cell proliferation and killing pancreatic cancer cells were measured by CCK-8 assay. Perforin, granzyme B (Gran B), CD107a, and NKG2D expressions of NK cells induced with apigenin were detected by flow cytometry (FCM). The mRNA expression of Bcl-2, Bax and protein expression of Bcl-2, Bax, p-ERK, and p-JNK in NK cells were evaluated by qRT-PCR and western blotting analysis, respectively. The results showed that appropriate concentration of apigenin could significantly promote the proliferation of NK cells in vitro and enhance the killing activity of NK cells against pancreatic cancer cells. The expressions of surface antigen NKG2D and intracellular antigen perforin and Gran B of NK cells were upregulated after treating with apigenin. Bcl-2 mRNA expression was increased, while Bax mRNA expression was decreased. Similarly, the expression of Bcl-2, p-JNK, and p-ERK protein was upregulated, and the expression of Bax protein was downregulated. The molecular mechanism of the immunopotentiation effects of apigenin may be that it up-regulates Bcl-2 and down-regulates Bax expression at the gene and protein levels to facilitate NK cell proliferation, and up-regulates the expression of perforin, Gran B, and NKG2D through the activation of JNK and ERK pathways to enhance NK cell cytotoxicity.

An Update on the Therapeutic Anticancer Potential of Ocimum sanctum L.: "Elixir of Life"

In most cases, cancer develops due to abnormal cell growth and subsequent tumour formation. Due to significant constraints with current treatments, natural compounds are being explored as potential alternatives. There are now around 30 natural compounds under clinical trials for the treatment of cancer. Tulsi, or Holy Basil, of the genus Ocimum, is one of the most widely available and cost-effective medicinal plants. In India, the tulsi plant has deep religious and medicinal significance. Tulsi essential oil contains a valuable source of bioactive compounds, such as camphor, eucalyptol, eugenol, alpha-bisabolene, beta-bisabolene, and beta-caryophyllene. These compounds are proposed to be responsible for the antimicrobial properties of the leaf extracts. The anticancer effects of tulsi (Ocimum sanctum L.) have earned it the title of "queen of herbs" and "Elixir of Life" in Ayurvedic treatment. Tulsi leaves, which have high concentrations of eugenol, have been shown to have anticancer properties. In a various cancers, eugenol exerts its antitumour effects through a number of different mechanisms. In light of this, the current review focuses on the anticancer benefits of tulsi and its primary phytoconstituent, eugenol, as apotential therapeutic agent against a wide range of cancer types. In recent years, tulsi has gained popularity due to its anticancer properties. In ongoing clinical trials, a number of tulsi plant compounds are being evaluated for their potential anticancer effects. This article discusses anticancer, chemopreventive, and antioxidant effects of tulsi.

Recent updates on anticancer mechanisms of polyphenols

In today’s scenario, when cancer cases are increasing rapidly, anticancer herbal compounds become imperative. Studies on the molecular mechanisms of action of polyphenols published in specialized databases such as Web of Science, Pubmed/Medline, Google Scholar, and Science Direct were used as sources of information for this review. Natural polyphenols provide established efficacy against chemically induced tumor growth with fewer side effects. They can sensitize cells to various therapies and increase the effectiveness of biotherapy. Further pharmacological translational research and clinical trials are needed to evaluate theirs in vivo efficacy, possible side effects and toxicity. Polyphenols can be used to design a potential treatment in conjunction with existing cancer drug regimens such as chemotherapy and radiotherapy.

The Potential Role of Apigenin in Cancer Prevention and Treatment

Cancer is the leading cause of death worldwide. In spite of advances in the treatment of cancer, currently used treatment modules including chemotherapy, hormone therapy, radiation therapy and targeted therapy causes adverse effects and kills the normal cells. Therefore, the goal of more effective and less side effects-based cancer treatment approaches is still at the primary position of present research. Medicinal plants or their bioactive ingredients act as dynamic sources of drugs due to their having less side effects and also shows the role in reduction of resistance against cancer therapy. Apigenin is an edible plant-derived flavonoid that has received significant scientific consideration for its health-promoting potential through modulation of inflammation, oxidative stress and various other biological activities. Moreover, the anti-cancer potential of apigenin is confirmed through its ability to modulate various cell signalling pathways, including tumor suppressor genes, angiogenesis, apoptosis, cell cycle, inflammation, apoptosis, PI3K/AKT, NF-κB, MAPK/ERK and STAT3 pathways. The current review mainly emphases the potential role of apigenin in different types of cancer through the modulation of various cell signaling pathways. Further studies based on clinical trials are needed to explore the role of apigenin in cancer management and explain the possible potential mechanisms of action in this vista.

Apigenin in cancer therapy: From mechanism of action to nano-therapeutic agent

Apigenin (APG) is a flavonoid presence in beverages, vegetables, and fruits containing anti-diabetic, anti-oxidant, and anti-viral activities, as well as cancer management properties. There is growing evidence that APG presented extensive anti-cancer effects in several cancer types by modulating various cellular processes, including angiogenesis, apoptosis, metastasis, autophagy, cell cycle, and immune responses, through activation or inhibition of different cell signaling pathways and molecules. By emerging nanotechnology and its advent in the biomedicine field, cancer therapy has been changed based on nanotechnology-based delivery systems. APG nanoformulations have been used to target tumor cells specifically, improve cellular uptake of APG, and overcome limitations of the free form of APG, such as low solubility and poor bioavailability. In this review, the biotherapeutic activity of APG and its mechanisms, both in free form and nanoformulation, toward cancer cells are discussed to shed some light on APG anti-tumor activity in different cancers.

Apigenin Targets MicroRNA-155, Enhances SHIP-1 Expression, and Augments Anti-Tumor Responses in Pancreatic Cancer

Pancreatic cancer (PC) is a deadly disease with a grim prognosis. Pancreatic tumor derived factors (TDF) contribute to the induction of an immunosuppressive tumor microenvironment (TME) that impedes the effectiveness of immunotherapy. PC-induced microRNA-155 (miRNA-155) represses expression of Src homology 2 (SH2) domain-containing Inositol 5'-phosphatase-1 (SHIP-1), a regulator of myeloid cell development and function, thus impacting anti-tumor immunity. We recently reported that the bioflavonoid apigenin (API) increased SHIP-1 expression which correlated with the expansion of tumoricidal macrophages (TAM) and improved anti-tumor immune responses in the TME of mice with PC. We now show that API transcriptionally regulates SHIP-1 expression via the suppression of miRNA-155, impacting anti-tumor immune responses in the bone marrow (BM) and TME of mice with PC. We discovered that API reduced miRNA-155 in the PC milieu, which induced SHIP-1 expression. This promoted the restoration of myelopoiesis and increased anti-tumor immune responses in the TME of heterotopic, orthotopic and transgenic SHIP-1 knockout preclinical mouse models of PC. Our results suggest that manipulating SHIP-1 through miR-155 may assist in augmenting anti-tumor immune responses and aid in the therapeutic intervention of PC.

Phytochemicals for the Prevention and Treatment of Renal Cell Carcinoma: Preclinical and Clinical Evidence and Molecular Mechanisms

Simple Summary

Renal cell carcinoma (RCC) is the most frequently diagnosed kidney cancer. Once RCC metastasizes, successful treatment is difficult to achieve. There is an apparent need for novel approaches to prevent and treat RCC. Phytochemicals are naturally derived compounds gaining increasing scientific interest due to their cancer preventive and chemotherapeutic properties. These phytochemicals have been shown to exhibit a multitude of anticancer effects against RCC. In this systematic review, we critically evaluate the potential these natural compounds possess for the prevention and treatment of RCC and discuss the future implications this may have in the fight against kidney cancer.

Abstract

Renal cell carcinoma (RCC) is associated with about 90% of renal malignancies, and its incidence is increasing globally. Plant-derived compounds have gained significant attention in the scientific community for their preventative and therapeutic effects on cancer. To evaluate the anticancer potential of phytocompounds for RCC, we compiled a comprehensive and systematic review of the available literature. Our work was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses criteria. The literature search was performed using scholarly databases such as PubMed, Scopus, and ScienceDirect and keywords such as renal cell carcinoma, phytochemicals, cancer, tumor, proliferation, apoptosis, prevention, treatment, in vitro, in vivo, and clinical studies. Based on in vitro results, various phytochemicals, such as phenolics, terpenoids, alkaloids, and sulfur-containing compounds, suppressed cell viability, proliferation and growth, showed cytotoxic activity, inhibited invasion and migration, and enhanced the efficacy of chemotherapeutic drugs in RCC. In various animal tumor models, phytochemicals suppressed renal tumor growth, reduced tumor size, and hindered angiogenesis and metastasis. The relevant antineoplastic mechanisms involved upregulation of caspases, reduction in cyclin activity, induction of cell cycle arrest and apoptosis via modulation of a plethora of cell signaling pathways. Clinical studies demonstrated a reduced risk for the development of kidney cancer and enhancement of the efficacy of chemotherapeutic drugs. Both preclinical and clinical studies displayed significant promise of utilizing phytochemicals for the prevention and treatment of RCC. Further research, confirming the mechanisms and regulatory pathways, along with randomized controlled trials, are needed to establish the use of phytochemicals in clinical practice.

Apigenin in cancer prevention and therapy: A systematic review and meta-analysis of animal models

BACKGROUND

Apigenin is being increasingly recognized as a cancer chemopreventive agent. We aimed to investigate the anticancer effects of Apigenin in in-vivo studies to know its present research status and how close or how far it is from the clinics.

METHODS

Several electronic databases such as PubMed, Springer, Cochrane, and ctri.gov.in were searched to fetch the relevant articles. We focused only on published animal studies that reported the anticancer effects of Apigenin against various cancers. Two reviewers independently assessed the risk of bias for each analysis, and the conflicting views were resolved later by consensus.

RESULTS

A total of 25 studies focused on the anticancer effects of Apigenin on various cancer types, including liver, prostate, pancreatic, lung, nasopharyngeal, skin, colon, colorectal, colitis-associated carcinoma, head and neck squamous cell carcinoma, leukemia, renal cell carcinoma, Ehrlich ascites carcinoma, and breast cancer were included. Overall, Apigenin reduces tumor volume (SMD=-3.597, 95% CI: -4.502 to -2.691, p < 0.001), tumor-weight (SMD=-2.213, 95% CI: -2.897 to -1.529, p < 0.001), tumor number (SMD=-1.081, 95% CI: -1.599 to -0.563, p < 0.001) and tumor load (SMD=-1.556, 95% CI: -2.336 to -0.776, p < 0.001). Further, it has no significant effect on the animal's body-weight (SMD=-0.345, 95% CI: -0.832 to 0.143, p = 0.165). Apigenin exerts anti-tumor effects mainly by inducing apoptosis/cell-cycle arrest.

CONCLUSIONS

Our analysis suggests that Apigenin has potential anticancer effects against various cancers. However, the poor symmetry of the funnel plot suggested publication bias. Thus, it warrants further research to evaluate the potential of Apigenin alone or as an adjuvant for cancer treatment.

A Novel Role of IL13Rα2 in the Pathogenesis of Proliferative Vitreoretinopathy

Proliferative vitreoretinopathy (PVR), an inflammatory and fibrotic blinding disease, is still a therapeutic challenge. Retinal pigment epithelial (RPE) cells dislodged in the vitreous play a central role in the PVR pathogenesis. To identify potential novel contributors to the pathogenesis of PVR, we investigated a profile of vitreous-induced changes in ARPE-19 cells by RNA sequencing. Bioinformatics analysis of the sequencing data showed that there were 258 genes up-regulated and 835 genes down-regulated in the ARPE-19 cells treated with human vitreous. Among these genes, there were three genes related to eye disease with more than threefold changes. In particular, quantitative PCR and western blot results showed that interleukin 13 receptor (IL13R)α2 that is over-expressed in a variety of cancers was up-regulated more than three times in the vitreous-treated ARPE-19 cells. Immunofluorescence analysis indicated that interleukin-13 receptor subunit α2 (IL13Rα2) was highly expressed in ARPE-19 cells within epiretinal membranes from patients with PVR. Importantly, blocking IL13Rα2 with its neutralizing antibody significantly inhibited vitreous-induced contraction of ARPE-19 cells, suggesting a novel role of IL13Rα2 in the PVR pathogenesis. These findings will improve our understanding of the molecular mechanisms by which PVR develops and provides potential targets for PVR therapeutics.

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.

The Effect of Encapsulated Apigenin Nanoparticles on HePG-2 Cells through Regulation of P53

Apigenin (Ap) is one of the most important natural flavonoids that has potent anticancer activity. This study was designed, for the first time, to load Ap into chitosan to improve its hydrophobicity and then it was coated with albumin-folic acid to increase its stability and bioavailability and to target cancer cells. The newly developed encapsulated Ap (Ap-CH-BSA-FANPs) was characterized and tested in vitro. The zeta potential of −17.0 mV was within the recommended range (−30 mV to +30 mV), indicating that encapsulated apigenin would not quickly settle and would be suspended. The in vitro results proved the great anticancer activity of the encapsulated apigenin on HePG-2 cells compared to pure Ap. The treated HePG-2 cells with Ap-CH-BSA-FANPs demonstrated the induction of apoptosis by increasing p53 gene expression, arresting the cell cycle, increasing caspase-9 levels, and decreasing both the MMP9 gene and Bcl-2 protein expression levels. Moreover, the higher antioxidant activity of the encapsulated apigenin treatment was evident through increasing SOD levels and decreasing the CAT concentration. In conclusion, the Ap-CH-BSA-FANPs were easy to produce with low coast, continued drug release, good loading capacity, high solubility in physiological pH, and were more stable than the formerly Ap-loaded liposomes or PLGA. Moreover, Ap-CH-BSA-FANPs may be a promising chemotherapeutic agent in the treatment of HCC.

Role of Induced Programmed Cell Death in the Chemopreventive Potential of Apigenin

The flavonoid apigenin (4′,5,7-trihydroxyflavone), which is one of the most widely distributed phytochemicals in the plant kingdom, is one of the most thoroughly investigated phenolic components. Previous studies have attributed the physiological effects of apigenin to its anti-allergic, antibacterial, antidiabetic, anti-inflammatory, antioxidant, antiviral, and blood-pressure-lowering properties, and its documented anticancer properties have been attributed to the induction of apoptosis and autophagy, the inhibition of inflammation, angiogenesis, and cell proliferation, and the regulation of cellular responses to oxidative stress and DNA damage. The most well-known mechanism for the compound’s anticancer effects in human cancer cell lines is apoptosis, followed by autophagy, and studies have also reported that apigenin induces novel cell death mechanisms, such as necroptosis and ferroptosis. Therefore, the aim of this paper is to review the therapeutic potential of apigenin as a chemopreventive agent, as well as the roles of programmed cell death mechanisms in the compound’s chemopreventive properties.

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.

Reactive oxygen species: Key players in the anticancer effects of apigenin?

Reactive oxygen species (ROS) exhibit a double-edged sword in cancer-hence their modulation has been an attractive strategy in cancer prevention and therapy. The abundance of scientific information on the pro-oxidant effects of apigenin in cancer cells suggests the crucial role of ROS in its mechanisms of action. Although apigenin is known to enhance the cellular ROS levels to cytotoxic degrees in cancer cells in vitro, it remains to be determined if these pro-oxidant effects prevail or are relevant in experimental tumor models and clinical trials. Here, we critically examine the pro-oxidant and antioxidant effects of apigenin in cancer to provide insightful perspectives on the association between its ROS-modulating action and anticancer potential. We also discussed these effects in a cell/tissue type-specific context to highlight the factors influencing the switch between antioxidant and pro-oxidant effects. Finally, we raised some questions that need addressing for the potential translation of these studies into clinical applications. Further research into this duality in oxidant actions of apigenin, especially in vivo, may enable better exploitation of its anticancer potential. PRACTICAL APPLICATION: Apigenin is a naturally occurring compound found in chamomile flowers, parsley, celery, peppermint, and citrus fruits. Many human trials of dietary interventions with apigenin-containing herbs and flavonoid mixture on oxidative stress markers, for instance, point to their antioxidant effects and health benefits in many diseases. Preclinical studies suggest that apigenin alone or its combination with chemotherapeutics has a strong anti-neoplastic effect and can induce ROS-mediated cytotoxicity at concentrations in the micromolar (μM) range, which may not be feasible with dietary interventions. Enhancing the in vivo pharmacokinetic properties of apigenin may be indispensable for its potential cancer-specific pro-oxidant therapy and may provide relevant information for clinical studies of apigenin either as a single agent or an adjuvant to chemotherapeutics.

Apigenin Induces Autophagy and Cell Death by Targeting EZH2 under Hypoxia Conditions in Gastric Cancer Cells

Hypoxia is a major obstacle to gastric cancer (GC) therapy and leads to chemoresistance as GC cells are frequently exposed to the hypoxia environment. Apigenin, a flavonoid found in traditional medicine, fruits, and vegetables and an HDAC inhibitor, is a powerful anti-cancer agent against various cancer cell lines. However, detailed mechanisms involved in the treatment of GC using APG are not fully understood. In this study, we investigated the biological activity of and molecular mechanisms involved in APG-mediated treatment of GC under hypoxia. APG promoted autophagic cell death by increasing ATG5, LC3-II, and phosphorylation of AMPK and ULK1 and down-regulating p-mTOR and p62 in GC. Furthermore, our results show that APG induces autophagic cell death via the activation of the PERK signaling, indicating an endoplasmic reticulum (ER) stress response. The inhibition of ER stress suppressed APG-induced autophagy and conferred prolonged cell survival, indicating autophagic cell death. We further show that APG induces ER stress- and autophagy-related cell death through the inhibition of HIF-1α and Ezh2 under normoxia and hypoxia. Taken together, our findings indicate that APG activates autophagic cell death by inhibiting HIF-1α and Ezh2 under hypoxia conditions in GC cells.

An In Vitro-In Vivo Evaluation of the Antiproliferative and Antiangiogenic Effect of Flavone Apigenin against SK-MEL-24 Human Melanoma Cell Line

One of the most important class of natural compounds with successful preclinical results in the management of cancer is the flavonoids. Due to the plethora of biological activities, apigenin (4',5,7 trihydroxyflavone) is a main representant of the flavone subclass. Although the antiproliferative and antiangiogenic effects of apigenin were studied on a significant number of human and murine melanoma cell lines, in order to complete the data existing in the literature, the aim of this study is to evaluate the in vitro effect of apigenin on SK-MEL-24 human melanoma cell line as well as in vivo on tumor angiogenesis using the aforementioned cell line on the chorioallantoic membrane assay. Results have shown that in the range of tested doses, the phytocompound presents significant antiproliferative, cytotoxic, and antimigratory potential at 30 μM, respectively, 60 μM. Moreover, the phytocompound in both tested concentrations limited melanoma cell growth and migration and induced a reduced angiogenic reaction limiting melanoma cell development.

Effects of Apigenin on the Expression of LOX-1, Bcl-2, and Bax in Hyperlipidemia Rats

We aimed to investigate the impact of apigenin on LOX-1, Bcl-2, and Bax expression in hyperlipidemia rats and explore the possible molecular pathological mechanism of apigenin in improving hyperlipidemia and preventing atherosclerosis. In hyperlipidemia models, the levels of total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-c) and the LOX-1 protein expression were apparently increased (P<0.01), while the high-density lipoprotein cholesterol (HDL-c) levels and the ratio of Bcl-2/Bax were reduced significantly (P<0.01) in comparison with the standard control group. After the treatment of apigenin, the levels of TC, TG, LDL-c, and the LOX-1 protein expression were noticeably decreased (P<0.01), while the levels of HDL-c and the Bcl-2/Bax ratio were increased (P<0.01). The intima was thickened and had protrusions in the hyperlipidemia model group compared to the normal control group. In comparison with the atherosclerosis model group, the degree of aortic lesions in the low-dose, middle-dose, high-dose groups was alleviated. Apigenin can reduce the level of blood lipid, improve hyperlipidemia, and prevent atherosclerosis in hyperlipidemia rats. The molecular mechanism may be related to inhibiting LOX-1 gene expression and increasing the Bcl-2/Bax ratio.

A nitric oxide-releasing prodrug promotes apoptosis in human renal carcinoma cells: Involvement of reactive oxygen species

Background

JS-K is a nitric oxide (NO)-releasing prodrug of the O2-arylated diazeniumdiolate group that shows pronounced cytotoxicity and antitumor properties in numerous cancer models, including in vitro as well as in vivo. Reactive oxygen species (ROS) induce carcinogenesis by altering the redox status, causing increment in vulnerability to oxidative stress.

Material and methods

To determine the effect of JS-K, a glutathione S-transferase (GST)-activated NO-donor prodrug, on the induction of ROS accumulation, proliferation, and apoptosis in human renal carcinoma cells, we measured the changes of cell proliferation, apoptosis, ROS growth, and initiation of the mitochondrial signaling pathway before and after JS-K treatment.

Results

In vitro, dose- and time-dependent development of renal carcinoma cells were controlled for JS-K, and JS-K also triggered ROS aggregation and cell apoptosis. Treatment with JS-K induces the levels of pro-apoptotic proteins (Bak and Bax) and decrease the number of anti-apoptotic protein (Bcl-2). In fact, JS-K-induced apoptosis was reversed by the antioxidant N-acetylcysteine, and oxidized glutathione, a pro-oxidant, improved JS-K-induced apoptosis. Finally, we demonstrated that in renal carcinoma cells, JS-K improved the chemosensitivity of doxorubicin.

Conclusion

Our data indicate that JS-K-released NO induce apoptosis of renal carcinoma cells by increasing ROS levels.

Protective effect of apigenin on ethylene glycol-induced urolithiasis via attenuating oxidative stress and inflammatory parameters in adult male Wistar rats

AIMS

Apigenin (4',5,7-trihydroxyflavone) is one of the subclasses of flavonoids and has various pharmacological effects. The present work was carried out to study the effect of apigenin on ethylene glycol-induced kidney damage in male Wistar rats.

MAIN METHODS

We evaluated the effects of apigenin orally administrated in normal and urolithiatic rats. Animals were assigned to nine groups in random: normal control; apigenin alone (0.005, 0.01, and 0.02 g/kg bw); urolithiatic control (0.75% ethylene glycol and 1.0% ammonium chloride in drinking water); apigenin (0.005, 0.01, and 0.02 g/kg bw) plus ethylene glycol and ammonium chloride; and cystone (0.75 g/kg bw) plus ethylene glycol and ammonium chloride. At the end of 28th day of treatment, animals were sacrificed for biochemical and histopathological assays.

KEY FINDINGS

Our results indicated that the apigenin treatment decreased the formation of urinary stones in urolithiatic rats. Also, apigenin reduced the generation of malondialdehyde and enhanced antioxidant enzymes activities in the kidney homogenate of rats. It also caused a significant decrease in the calcium oxalate crystals numbers in urinary sample of rats with ethylene glycol-induced hyperoxaluria. These findings were supported by histopathological examinations.

SIGNIFICANCE

Based on the results obtained, apigenin attenuate ethylene glycol-related kidney damage in male Wistar rats. Although the underlying mechanism of apigenin effect has not been determined, reduction of urinary levels of stone-producing constituents, antioxidant activities, and inhibition of TGF-β signaling may be involved.

A novel Apigenin derivative suppresses renal cell carcinoma via directly inhibiting wild-type and mutant MET

MET, the receptor of hepatocyte growth factor (HGF), is a driving factor in renal cell carcinoma (RCC) and also a proven drug target for cancer treatment. To improve the activity and to investigate the mechanisms of action of Apigenin (APG), novel derivatives of APG with improved properties were synthesized and their activities against Caki-1 human renal cancer cell line were evaluated. It was found that compound 15e exhibited excellent potency against the growth of multiple RCC cell lines including Caki-1, Caki-2 and ACHN and is superior to APG and Crizotinib. Subsequent investigations demonstrated that compound 15e can inhibit Caki-1 cell proliferation, migration and invasion. Mechanistically, 15e directly targeted the MET kinase domain, decreased its auto-phosphorylation at Y1234/Y1235 and inhibited its kinase activity and downstream signaling. Importantly, 15e had inhibitory activity against mutant MET V1238I and Y1248H which were resistant to approved MET inhibitors Cabozantinib, Crizotinib or Capmatinib. In vivo tumor graft study confirmed that 15e repressed RCC growth through inhibition of MET activation. These results indicate that compound 15e has the potential to be developed as a treatment for RCC, and especially against drug-resistant MET mutations.

Apigenin Inhibits the Growth of Hepatocellular Carcinoma Cells by Affecting the Expression of microRNA Transcriptome

Background

Apigenin, as a natural flavonoid, has low intrinsic toxicity and has potential pharmacological effects against hepatocellular carcinoma (HCC). However, the molecular mechanisms involving microRNAs (miRNAs) and their target genes regulated by apigenin in the treatment of HCC have not been addressed.

Objective

In this study, the molecular mechanisms of apigenin involved in the prevention and treatment of HCC were explored in vivo and in vitro using miRNA transcriptomic sequencing to determine the basis for the clinical applications of apigenin in the treatment of HCC.

Methods

The effects of apigenin on the proliferation, cell cycle progression, apoptosis, and invasion of human hepatoma cell line Huh7 and Hep3B were studied in vitro, and the effects on the tumorigenicity of Huh7 cells were assessed in vivo. Then, a differential expression analysis of miRNAs regulated by apigenin in Huh7 cells was performed using next-generation RNA sequencing and further validated by qRT-PCR. The potential genes targeted by the differentially expressed miRNAs were identified using a curated miRTarBase miRNA database and their molecular functions were predicted using Gene Ontology and KEGG signaling pathway analysis.

Results

Compared with the control treatment group, apigenin significantly inhibited Huh7 cell proliferation, cell cycle, colony formation, and cell invasion in a concentration-dependent manner. Moreover, apigenin reduced tumor growth, promoted tumor cell necrosis, reduced the expression of Ki67, and increased the expression of Bax and Bcl-2 in the xenograft tumors of Huh7 cells. Bioinformatics analysis of the miRNA transcriptome showed that hsa-miR-24, hsa-miR-6769b-3p, hsa-miR-6836-3p, hsa-miR-199a-3p, hsa-miR-663a, hsa-miR-4739, hsa-miR-6892-3p, hsa-miR-7107-5p, hsa-miR-1273g-3p, hsa-miR-1343, and hsa-miR-6089 were the most significantly up-regulated miRNAs, and their key gene targets were MAPK1, PIK3CD, HRAS, CCND1, CDKN1A, E2F2, etc. The core regulatory pathways of the up-regulated miRNAs were associated with the hepatocellular carcinoma pathway. The down-regulated miRNAs were hsa-miR-181a-5p and hsa-miR-148a-3p, and the key target genes were MAPK1, HRAS, STAT3, FOS, BCL2, SMAD2, PPP3CA, IFNG, MET, and VAV2, with the core regulatory pathways identified as proteoglycans in cancer pathway.

Conclusion

Apigenin can inhibit the growth of HCC cells, which may be mediated by up-regulation or down-regulation of miRNA molecules and their related target genes.

Apigenin role as cell-signaling pathways modulator: implications in cancer prevention and treatment

Cancer is a complex disease orchestrated by various extrinsic and intrinsic pathways. In recent years, there has been a keen interest towards the development of natural extracts-based cancer therapeutics with minimum adverse effects. In pursuit of effective strategy, a wide variety of natural products-derived compounds have been addressed for their anticancer effects. Apigenin is a naturally-occurring flavonoid present abundantly in various fruits and vegetables. Decades of research have delineated the pharmacological and biological properties of apigenin. Specifically, the apigenin-mediated anticancer activities have been documented in various types of cancer, but the generalized scientific evidence encompassing various molecular interactions and processes, such as regulation of the apoptotic machinery, aberrant cell signaling and oncogenic protein network have not been comprehensively covered. In this sense, in this review we have attempted to focus on the apigenin-mediated regulation of oncogenic pathways in various cancers. We have also addressed the cutting-edge research which has unveiled the remarkable abilities of apigenin to interact with microRNAs to modulate key cellular processes, with special emphasis on the nano-formulations of apigenin that can help their targeted delivery and can be a therapeutic solution for the treatment of various cancers.

Critical roles of Rad54 in tolerance to apigenin-induced Top1-mediated DNA damage

Apigenin (APG), a flavone sub-class of flavonoids, possesses a diverse range of biological activities, including anti-cancer and anti-inflammatory effects. Previous studies identified the genotoxicity of APG in certain cancer cells, which may be associated with its anticancer effect. However, the DNA damage repair mechanism induced by APG has remained elusive. In order to clarify the molecular mechanisms, the present study determined the toxicity of APG to the wild-type (WT) DT40 chicken B-lymphocyte cell line, as well as to DT40 cells with deletions in various DNA repair genes, and their sensitivities were compared. It was demonstrated that cells deficient of Rad54, a critical homologous recombination gene, were particularly sensitive to APG. Cell-cycle analysis demonstrated that APG caused an increase in the G₂/M-phase population of Rad54^{- / -} cells that was greater than that in WT cells. Furthermore, it was demonstrated by immunofluorescence assay that Rad54^{- / -} cells exhibited significantly increased numbers of γ-phosphorylated H2AX variant histone foci and chromosomal aberrations compared to the WT cells in response to APG. Of note, the in vitro complex of enzyme assay indicated that APG induced increased topoisomerase I (Top1) covalent protein DNA complex in Rad54^{- / -} cells compared to WT cells. Finally, these results were verified using the TK6 human lymphoblastoid cell line and it was demonstrated that, as for DT40 cells, Rad54 deficiency sensitized TK6 cells to APG. The present study demonstrated that Rad54 was involved in the repair of APG-induced DNA damage, which was associated with Top1 inhibition.

Anticancer activity of flavonoids accompanied by redox state modulation and the potential for a chemotherapeutic strategy

Since researchers began studying the mechanism of flavonoids' anticancer activity, little attention has been focused on the modulation of redox state in cells as a potential chemotherapeutic strategy. However, recent studies have begun identifying that the anticancer effect of flavonoids occurs both in their antioxidative activity which scavenges ROS and their prooxidative activity which generates ROS. Against this backdrop, this study attempts to achieve a comprehensive analysis of the individual and separate study findings regarding flavonoids' modulation of redox state in cancer cells. It focuses on the mechanism behind the anticancer effect, and mostly on the modulation of redox potential by flavonoids such as quercetin, hesperetin, apigenin, genistein, epigallocatechin-3-gallate (EGCG), luteolin and kaempferol in both in vitro and animal models. In addition, the clinical applications of and bioavailability of flavonoids were reviewed to help build a treatment strategy based on flavonoids' prooxidative potential.

Rationalizing the therapeutic potential of apigenin against cancer

BACKGROUND

Despite the remarkable advances made in the diagnosis and treatment of cancer during the past couple of decades, it remains the second largest cause of mortality in the world, killing approximately 9.6 million people annually. The major challenges in the treatment of the advanced stage of this disease are the development of chemoresistance, severe adverse effects of the drugs, and high treatment cost. Therefore, the development of drugs that are safe, efficacious, and cost-effective remains a 'Holy Grail' in cancer research. However, the research over the past four decades shed light on the cancer-preventive and therapeutic potential of natural products and their underlying mechanism of action. Apigenin is one such compound, which is known to be safe and has significant potential in the prevention and therapy of this disease.

AIM

To assess the literature available on the potential of apigenin and its analogs in modulating the key molecular targets leading to the prevention and treatment of different types of cancer.

METHOD

A comprehensive literature search has been carried out on PubMed for obtaining information related to the sources and analogs, chemistry and biosynthesis, physicochemical properties, biological activities, bioavailability and toxicity of apigenin.

KEY FINDINGS

The literature search resulted in many in vitro, in vivo and a few cohort studies that evidenced the effectiveness of apigenin and its analogs in modulating important molecular targets and signaling pathways such as PI3K/AKT/mTOR, JAK/STAT, NF-κB, MAPK/ERK, Wnt/β-catenin, etc., which play a crucial role in the development and progression of cancer. In addition, apigenin was also shown to inhibit chemoresistance and radioresistance and make cancer cells sensitive to these agents. Reports have further revealed the safety of the compound and the adaptation of nanotechnological approaches for improving its bioavailability.

SIGNIFICANCE

Hence, the present review recapitulates the properties of apigenin and its pharmacological activities against different types of cancer, which warrant further investigation in clinical settings.

Cytotoxic and Apoptotic Effects of Luffa Cylindrica Leaves Extract against Acute Lymphoblastic Leukemic Stem Cells

BACKGROUND

Acute lymphoblastic leukemia (ALL) is an aggressive malignancy defined by accumulation of lymphoblasts in the bone marrow. Leukemic stem cells (LSCs) are the major cause of the recurrence and metastasis of ALL. This study aimed to develop an effective anti-cancer agent targeting these LSCs. Luffa Cylindrica (L.C.) leaves extract was selected to evaluate its effect on ALL via eradicating the LSCs as it contains many active anti-cancer flavonoids.

METHODS

Thirty-two bone marrow samples of ALL patients were used in this study. LSCs population was identified in the selected samples. Cell viability was measured by MTT assay and flow cytometry. Cell cycle, apoptosis, proliferation marker; ki-67 and colony forming assay were further analyzed.

RESULTS

This study revealed the expression of CD34+/CD38+ cells in addition to CD34+/CD38- population and the extract was effective against the two LSCs populations. MTT assay showed that treated leukemic cells exhibited significant reduction in the viable cells in a dose dependent manner with IC50 of 3 µg/µl which was then confirmed by flow cytometry. Cell cycle analysis results showed significant reduction in the percentage of cells treated with L.C. extract in both the S and G0/G1 phases, with concomitant increase in the G2/M phase. Also, L.C. extract could effectively induce apoptosis, inhibit proliferation and suppress colonogenecity of leukemic cells.

CONCLUSION

This study validated the medicinal potential of L.C. leaves extract as a promising anti-leukemic agent targeting both LSCs and blasts in ALL patients, which may be explained by the synergy found between its potent flavonoids especially apigenin, luteolin and kaempferol.

Flavonoids as Multi-Target Compounds: A Special Emphasis on their Potential as Chemo-adjuvants in Cancer Therapy

Flavonoids are low molecular weight, polyphenolic phytochemicals, obtained from secondary metabolism of various plant compounds. They have a spectrum of pharmacological efficacies, including potential anticancer efficacy. Natural flavonoids are present in fruits, vegetables, grains, bark, roots, stems, flowers, tea and wine. Flavonoids can attenuate or inhibit the initiation, promotion and progression of cancer by modulating various enzymes and receptors in diverse pathways that involve cellular proliferation, differentiation, apoptosis, inflammation, angiogenesis and metastasis. Furthermore, in vitro, flavonoids have been shown to reverse multidrug resistance when used as chemo-adjuvants. Flavonoids (both natural and synthetic analogues) interact with several oncogenic targets through dependent and independent mechanisms to mediate their anticancer efficacy in different types of cancer cells.

Apigenin as Tumor Suppressor in Cancers: Biotherapeutic Activity, Nanodelivery, and Mechanisms With Emphasis on Pancreatic Cancer

Pancreatic cancer is the most lethal malignancy of the gastrointestinal tract. Due to its propensity for early local and distant spread, affected patients possess extremely poor prognosis. Currently applied treatments are not effective enough to eradicate all cancer cells, and minimize their migration. Besides, these treatments are associated with adverse effects on normal cells and organs. These therapies are not able to increase the overall survival rate of patients; hence, finding novel adjuvants or alternatives is so essential. Up to now, medicinal herbs were utilized for therapeutic goals. Herbal-based medicine, as traditional biotherapeutics, were employed for cancer treatment. Of them, apigenin, as a bioactive flavonoid that possesses numerous biological properties (e.g., anti-inflammatory and anti-oxidant effects), has shown substantial anticancer activity. It seems that apigenin is capable of suppressing the proliferation of cancer cells via the induction of cell cycle arrest and apoptosis. Besides, apigenin inhibits metastasis via down-regulation of matrix metalloproteinases and the Akt signaling pathway. In pancreatic cancer cells, apigenin sensitizes cells in chemotherapy, and affects molecular pathways such as the hypoxia inducible factor (HIF), vascular endothelial growth factor (VEGF), and glucose transporter-1 (GLUT-1). Herein, the biotherapeutic activity of apigenin and its mechanisms toward cancer cells are presented in the current review to shed some light on anti-tumor activity of apigenin in different cancers, with an emphasis on pancreatic cancer.

Apigenin Attenuates the Allergic Reactions by Competitively Binding to ER With Estradiol

Apigenin (API) is a natural phytoestrogen with properties including anti-inflammatory and other abilities. This study aims to 1) systematically validate that excessive estrogen exacerbates allergic reactions; 2) explore the anti-allergic effects and mechanisms of API. We conduct a survey of college students, indicating that of the 505 effective results, 70 individuals were self-reported allergic and 74.1% of them were women, which proved the gender difference in allergic reactions. BALB/c mice are grouped into the negative control group (N-Ctrl), the OVA-sensitized group (P-Ctrl), the estrogenized OVA-sensitized group (E2), and three treatment groups administrating different dose of API (E2 + API/L/M/H). In vivo data indicated that API treatment significantly inhibited the enhancement of estradiol on clinical symptoms. Moreover, we found that high doses of API inhibited Th2 type humoral response and mast cell degranulation levels in vivo and in vitro. Additionally, medium, and high doses of API significantly reduced the potentiation of estradiol on ER expression, attenuated the transmission of estrogen/ER signaling, thereby inhibiting the phosphorylation of ERK1/2 and JNK1/2/3 in the MAPK. Besides, we found that API competitively bound to ER with estradiol, and showed a weak selectivity to ERβ. Overall, we identified API can be beneficial in allergic disease.

Putative Inhibitors of SARS-CoV-2 Main Protease from A Library of Marine Natural Products: A Virtual Screening and Molecular Modeling Study

The current emergency due to the worldwide spread of the COVID-19 caused by the new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a great concern for global public health. Already in the past, the outbreak of severe acute respiratory syndrome (SARS) in 2003 and Middle Eastern respiratory syndrome (MERS) in 2012 demonstrates the potential of coronaviruses to cross-species borders and further underlines the importance of identifying new-targeted drugs. An ideal antiviral agent should target essential proteins involved in the lifecycle of SARS-CoV. Currently, some HIV protease inhibitors (i.e., Lopinavir) are proposed for the treatment of COVID-19, although their effectiveness has not yet been assessed. The main protease (Mpr) provides a highly validated pharmacological target for the discovery and design of inhibitors. We identified potent Mpr inhibitors employing computational techniques that entail the screening of a Marine Natural Product (MNP) library. MNP library was screened by a hyphenated pharmacophore model, and molecular docking approaches. Molecular dynamics and re-docking further confirmed the results obtained by structure-based techniques and allowed this study to highlight some crucial aspects. Seventeen potential SARS-CoV-2 Mpr inhibitors have been identified among the natural substances of marine origin. As these compounds were extensively validated by a consensus approach and by molecular dynamics, the likelihood that at least one of these compounds could be bioactive is excellent.

Flavonoids as Anticancer Agents

Flavonoids are polyphenolic compounds subdivided into 6 groups: isoflavonoids, flavanones, flavanols, flavonols, flavones and anthocyanidins found in a variety of plants. Fruits, vegetables, plant-derived beverages such as green tea, wine and cocoa-based products are the main dietary sources of flavonoids. Flavonoids have been shown to possess a wide variety of anticancer effects: they modulate reactive oxygen species (ROS)-scavenging enzyme activities, participate in arresting the cell cycle, induce apoptosis, autophagy, and suppress cancer cell proliferation and invasiveness. Flavonoids have dual action regarding ROS homeostasis—they act as antioxidants under normal conditions and are potent pro-oxidants in cancer cells triggering the apoptotic pathways and downregulating pro-inflammatory signaling pathways. This article reviews the biochemical properties and bioavailability of flavonoids, their anticancer activity and its mechanisms of action.

Heavy metal accumulation and genotoxic effects in levant vole (Microtus guentheri) collected from contaminated areas due to mining activities

Heavy metal contamination is a serious environmental problem commonly monitored in various organisms. Small wild rodents are ideal biological monitors to show the extent of environmental pollution. The aim of this study was to evaluate the adverse effects of marble and stone quarries on the Levant vole, Microtus guentheri, inhabiting some polluted sites. In this context, Inductively Coupled Plasma Mass Spectrometry (ICP-MS) was used to analyze distribution of thirteen heavy metals (Fe, Al, Zn, Cu, Cr, Mn, Ni, B, Pb, As, Co, Cd, and Hg) in the organs (skins, bones, muscles, livers and kidneys) of the biological specimens, and the comet assay revealed DNA damage in blood lymphocytes for the first time. This study was conducted at close to the marble and stone quarries at Korkuteli, Antalya-Turkey during spring, summer, autumn (2017) and winter (2018) seasons. In spring and summer, genetic damage in blood lymphocytes from all polluted sites (sites 1-5) was significantly higher than that of controls, while in autumn it was higher in samples from three sites (sites 3-5). In terms of heavy metal distribution in organs, we found depositions of Fe, Al, Zn, Ni, Mn, Cr, Co, As and Pb primarily in the skin with its derivatives, Cu and Cd deposits in the kidney, Cu, Cd and B deposits in the liver, and As and Pb depositions in the bones. The study shows that certain organs (especially skin with its derivatives) and blood lymphocytes of Levant vole can be used as ideal indicators of heavy metal pollution. Our results suggest that the Korkuteli area could already be under the threat of heavy metal pollution.

Apigenin, a flavonoid constituent derived from P. villosa, inhibits hepatocellular carcinoma cell growth by CyclinD1/CDK4 regulation via p38 MAPK-p21 signaling

Hepatocellular carcinoma (HCC) is a leading cause of cancer mortality worldwide. Apigenin was widely used in HCC treatment; however, the detailed mechanisms have not been clarified. We isolated, characterized, and identified Apigenin from the P. villosa plant using ethanol-extracted, semi-preparative HPLC and NMR. MTT was used to detect the cytotoxicity of Apigenin in HepG2, SMMC-7721 and Huh-7 cell lines. The cell cycle changes of Apigenin on HepG2 using flow cytometry and the key molecules of cell cycle regulation by RT-qPCR and Western blot. Apigenin was ethanol-extracted and semi-preparative HPLC was used for isolation and purification. The compounds were identified and the results showed Apigenin was one of the bioactive compounds. Apigenin exhibited relatively high cytotoxicity in HepG2, SMMC-7721, and Huh-7. Cell cycle analysis showed that Apigenin could induce G1 arrest in HepG2 in a dose-dependent manner. CyclinD1 was up-regulated and CDK4 was down-regulated upon Apigenin treatment, which indicated that Apigenin could block cell cycle progression at the G1 phase though the regulation of CDK4 and CyclinD1 expression. In conclusion, the present findings might provide new insights about the implication of Apigenin and P. villosa in cancer therapy.

Assessing Anticancer Potential of Blueberry Flavonoids, Quercetin, Kaempferol, and Gentisic Acid, Through Oxidative Stress and Apoptosis Parameters on HCT-116 Cells

In recent years, natural products gained popularity with their anti-inflammatory and antioxidant effects mediated by chemical compounds within their composition. Study results offering them as palliative therapy options in cancer or as anticancer agents with high levels of cytotoxicity brought a new approach to combine cancer treatment protocols with these products. From a different perspective, edible types of these products are suggested in daily diets due to their potential cancer preventive effects. Our preliminary work was on blueberry extracts (Vaccinium myrtillus) as a main representative of these natural products, and the contents of the extracts were analyzed with liquid chromatography tandem mass spectrometry (LC MS/MS) to reveal the composition and distribution of polyphenolic compounds within. The most abundant polyphenols detected in V. myrtillus extracts were quercetin, kaempferol, and a phenolic acid, gentisic acid (GA). The compounds were further evaluated on treated HCT-116 cells for their potential anticancer effects by measuring total antioxidant status, total oxidant status, and 8-hydroxydeoxyguanosine levels for evaluation of oxidative stress and through protein array analysis and flow cytometric analysis for evaluation of apoptosis. In analysis of oxidative stress parameters, reduced total oxidant levels and reduced oxidative stress index levels were found in cells treated with the compounds in comparison with untreated cells. In apoptosis-related protein profiles, at least twofold reduction in various apoptotic proteins was observed after quercetin and kaempferol treatment, whereas a different profile was observed for GA. Overall, results of this study showed that quercetin and kaempferol have strong cytotoxic, antioxidant, and apoptotic effects, although GA is mostly effective as an antioxidant polyphenol on HCT-116 cells.

Dietary Polyphenols-Important Non-Nutrients in the Prevention of Chronic Noncommunicable Diseases. A Systematic Review

The improvement of the social and economic conditions of society has eliminated the threat of death from the majority of infectious diseases. However, the rapid progress of civilization has created new possibilities for the appearance of factors with adverse effects for the health of society. This has led to increased morbidity from certain diseases, the presence of which had not been observed several centuries ago. Chronic noncommunicable diseases (e.g., cancers, cardio-vascular disorders, diabetes, obesity, neurodegenerative diseases) result from an inappropriate relationship between people and their environment. The common characteristic for all chronic diseases is a “new” form of inflammation, very often called metaflammation, which is considered as a subclinical, permanent inflammation. As a result, metabolic cascade, including cellular oxidative stress, atherosclerotic process, and insulin resistance, occurs, which slowly generates significant deterioration in the organism. Polyphenols are the major group of non-nutrients, considering their diversity, food occurrence, and biological properties. The current review aims to present a wide spectrum of literature data, including the molecular mechanism of their activity and experimental model used, and summarize the recent findings on the multitude of physiological effects of dietary polyphenols towards the prevention of several chronic diseases. However, despite several studies, the estimation of their dietary intake is troublesome and inconclusive, which will be also discussed.

Flavonoids in Cancer and Apoptosis

Cancer is the second leading cause of death globally. Although, there are many different approaches to cancer treatment, they are often painful due to adverse side effects and are sometimes ineffective due to increasing resistance to classical anti-cancer drugs or radiation therapy. Targeting delayed/inhibited apoptosis is a major approach in cancer treatment and a highly active area of research. Plant derived natural compounds are of major interest due to their high bioavailability, safety, minimal side effects and, most importantly, cost effectiveness. Flavonoids have gained importance as anti-cancer agents and have shown great potential as cytotoxic anti-cancer agents promoting apoptosis in cancer cells. In this review, a summary of flavonoids and their effectiveness in cancer treatment targeting apoptosis has been discussed.

Flavonoids in Kidney Health and Disease

This review summarizes the latest advances in knowledge on the effects of flavonoids on renal function in health and disease. Flavonoids have antihypertensive, antidiabetic, and antiinflammatory effects, among other therapeutic activities. Many of them also exert renoprotective actions that may be of interest in diseases such as glomerulonephritis, diabetic nephropathy, and chemically-induced kidney insufficiency. They affect several renal factors that promote diuresis and natriuresis, which may contribute to their well-known antihypertensive effect. Flavonoids prevent or attenuate the renal injury associated with arterial hypertension, both by decreasing blood pressure and by acting directly on the renal parenchyma. These outcomes derive from their interference with multiple signaling pathways known to produce renal injury and are independent of their blood pressure-lowering effects. Oral administration of flavonoids prevents or ameliorates adverse effects on the kidney of elevated fructose consumption, high fat diet, and types I and 2 diabetes. These compounds attenuate the hyperglycemia-disrupted renal endothelial barrier function, urinary microalbumin excretion, and glomerular hyperfiltration that results from a reduction of podocyte injury, a determinant factor for albuminuria in diabetic nephropathy. Several flavonoids have shown renal protective effects against many nephrotoxic agents that frequently cause acute kidney injury (AKI) or chronic kidney disease (CKD), such as LPS, gentamycin, alcohol, nicotine, lead or cadmium. Flavonoids also improve cisplatin- or methotrexate-induced renal damage, demonstrating important actions in chemotherapy, anticancer and renoprotective effects. A beneficial prophylactic effect of flavonoids has been also observed against AKI induced by surgical procedures such as ischemia/reperfusion (I/R) or cardiopulmonary bypass. In several murine models of CKD, impaired kidney function was significantly improved by the administration of flavonoids from different sources, alone or in combination with stem cells. In humans, cocoa flavanols were found to have vasculoprotective effects in patients on hemodialysis. Moreover, flavonoids develop antitumor activity against renal carcinoma cells with no toxic effects on normal cells, suggesting a potential therapeutic role in patients with renal carcinoma.

Cytochrome P450 CYP1 metabolism of hydroxylated flavones and flavonols: Selective bioactivation of luteolin in breast cancer cells

Natural flavonoids with methoxy substitutions are metabolized by CYP1 enzymes to yield the corresponding demethylated products. The present study aimed to characterize the metabolism and further antiproliferative activity of the hydroxylated flavonoids apigenin, luteolin, scutellarein, kaempferol and quercetin in CYP1 recombinant enzymes and in the CYP1 expressing cell lines MCF7 and MDA-MB-468, respectively. Apigenin was converted to luteolin and scutellarein, whereas kaempferol was metabolized only to quercetin by recombinant CYP1 enzymes. Luteolin metabolism yielded 6 hydroxyluteolin only by recombinant CYP1B1, whereas CYP1A1 and CYP1A2 were not capable of metabolizing this compound. Molecular modeling demonstrated that CYP1B1 favored the A ring orientation of apigenin and luteolin to the heme group compared with CYP1A1. The IC50 of the compounds luteolin, scutellarein and 6 hydroxyluteolin was significantly lower in MDA-MB-468, MCF7 and MCF10A cells compared with that of apigenin. Similarly, the IC50 of quercetin in MDA-MB-468 cells was significantly lower compared with that of kaempferol. The most potent compound was luteolin in MDA-MB-468 cells (IC50 = 2 ± 0.3 μM). In the presence of the CYP1-inhibitors α-napthoflavone and/or acacetin, luteolin activation was lessened. Taken collectively, the data demonstrate that the metabolism of hydroxylated flavonoids by cytochrome P450 CYP1 enzymes, notably CYP1A1 and CYP1B1, can enhance their antiproliferative activity in breast cancer cells. In addition, this antiproliferative activity is attributed to the combined action of the parent compound and the corresponding CYP1 metabolites.

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.