Apigenin enhances the antitumor effects of cetuximab in nasopharyngeal carcinoma by inhibiting EGFR signaling

Exploiting new strategies in combating head and neck carcinoma: A comprehensive review on phytochemical approaches passing through PI3K/Akt/mTOR signaling pathway

Recently, malignant neoplasms have growingly caused human morbidity and mortality. Head and neck cancer (HNC) constitutes a substantial group of malignancies occurring in various anatomical regions of the head and neck, including lips, mouth, throat, larynx, nose, sinuses, oropharynx, hypopharynx, nasopharynx, and salivary glands. The present study addresses the phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) pathway as a possible therapeutic target in cancer therapy. Finding new multitargeting agents capable of modulating PI3K/Akt/mTOR and cross-linked mediators could be viewed as an effective strategy in combating HNC. Recent studies have introduced phytochemicals as multitargeting agents and rich sources for finding and developing new therapeutic agents. Phytochemicals have exhibited immense anticancer effects, including targeting different stages of HNC through the modulation of several signaling pathways. Moreover, phenolic/polyphenolic compounds, alkaloids, terpenes/terpenoids, and other secondary metabolites have demonstrated promising anticancer activities because of their diverse pharmacological and biological properties like antiproliferative, antineoplastic, antioxidant, and anti-inflammatory activities. The current review is mainly focused on new therapeutic strategies for HNC passing through the PI3K/Akt/mTOR pathway as new strategies in combating HNC.

Apigenin and Temozolomide Synergistically Inhibit Glioma Growth Through the PI3K/AKT Pathway

Background: Glioma is a devastating disease with the worst prognosis among human malignant tumors. Although temozolomide (TMZ) improves the overall survival of glioma patients, there are still many glioma patients who are resistant to TMZ. In this study, we focused on the effect of apigenin (API) and TMZ on glioma cells in vitro and in vivo, and we studied the underlying molecular mechanisms. Materials and Methods: To investigate the effect of API on glioblastoma cell proliferation, cell viability was assessed after glioma cells were incubated with various concentrations of API with or without TMZ using MTT assays. Then, we explored the synergistic effect of API and TMZ on glioma cell cycle, apoptosis, and migration. To investigate the molecular mechanism behind the synergism of API and TMZ, we examined the related genes of the major signaling pathways involved in glioma pathogenesis by Western blotting. Results: In this study, we found that API significantly suppressed the proliferation of glioma cells in a dose- and time-dependent manner. Combining API and TMZ significantly induced glioma cells arrest at the G2 phase and inhibited glioma cells proliferation compared with API or TMZ alone. In addition, API promoted the ability of TMZ to induce glioma cells apoptosis and inhibit glioma cells invasion. Furthermore, compared with treatment with individual agents, the combination of API and TMZ significantly inhibited the growth of subcutaneous tumors in mice. These results implied that API could synergistically suppress the growth of glioma cells when combined with TMZ. Combining API and TMZ significantly inhibited the protein expression of p-AKT, cyclin D1, Bcl-2, Matrix Metallopeptidase 2, and Matrix Metallopeptidase 9. Conclusion: API and TMZ synergistically inhibited glioma growth through the PI3K/AKT pathway.

Cyclic increase in the ADAMTS1-L1CAM-EGFR axis promotes the EMT and cervical lymph node metastasis of oral squamous cell carcinoma

The matrix metalloprotease A disintegrin and metalloprotease with thrombospondin motifs 1 (ADAMTS1) was reported to be involved in tumor progression in several cancer types, but its contributions appear discrepant. At present, the role of ADAMTS1 in oral squamous cell carcinoma (SCC; OSCC) remains unclear. Herein, The Cancer Genome Atlas (TCGA) database showed that ADAMTS1 transcripts were downregulated in head and neck SCC (HNSCC) tissues compared to normal tissues, but ADAMTS1 levels were correlated with poorer prognoses of HNSCC patients. In vitro, we observed that ADAMTS1 expression levels were correlated with the invasive abilities of four OSCC cell lines, HSC-3, SCC9, HSC-3M, and SAS. Knockdown of ADAMTS1 in OSCC cells led to a decrease and its overexpression led to an increase in cell-invasive abilities in vitro as well as tumor growth and lymph node (LN) metastasis in OSCC xenografts. Mechanistic investigations showed that the cyclic increase in ADAMTS1-L1 cell adhesion molecule (L1CAM) axis-mediated epidermal growth factor receptor (EGFR) activation led to exacerbation of the invasive abilities of OSCC cells via inducing epithelial-mesenchymal transition (EMT) progression. Clinical analyses revealed that ADAMTS1, L1CAM, and EGFR levels were all correlated with worse prognoses of HNSCC patients, and patients with ADAMTS1high/L1CAMhigh or EGFRhigh tumors had the shortest overall and disease-specific survival times. As to therapeutic aspects, we discovered that an edible plant-derived flavonoid, apigenin (API), drastically inhibited expression of the ADAMTS1-L1CAM-EGFR axis and reduced the ADAMTS1-triggered invasion and LN metastasis of OSCC cells in vitro and in vivo. Most importantly, API treatment significantly prolonged survival rates of xenograft mice with OSCC. In summary, ADAMTS1 may be a useful biomarker for predicting OSCC progression, and API potentially retarded OSCC progression by targeting the ADAMTS1-L1CAM-EGFR signaling pathway.

Flavonoids as promising anticancer therapeutics: Contemporary research, nanoantioxidant potential, and future scope

Flavonoids are natural polyphenolic compounds considered safe, pleiotropic, and readily available molecules. It is widely distributed in various food products such as fruits and vegetables and beverages such as green tea, wine, and coca-based products. Many studies have reported the anticancer potential of flavonoids against different types of cancers, including solid tumors. The chemopreventive effect of flavonoids is attributed to various mechanisms, including modulation of autophagy, induction of cell cycle arrest, apoptosis, and antioxidant defense. Despite of significant anticancer activity of flavonoids, their clinical translation is limited due to their poor biopharmaceutical attributes (such as low aqueous solubility, limited permeability across the biological membranes (intestinal and blood-brain barrier), and stability issue in biological systems). A nanoparticulate system is an approach that is widely utilized to improve the biopharmaceutical performance and therapeutic efficacy of phytopharmaceuticals. The present review discusses the significant anticancer potential of promising flavonoids in different cancers and the utilization of nanoparticulate systems to improve their nanoantioxidant activity further to enhance the anticancer activity of loaded promising flavonoids. Although, various plant-derived secondary metabolites including flavonoids have been recommended for treating cancer, further vigilant research is warranted to prove their translational values.

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.

The Involvement of Natural Polyphenols in Molecular Mechanisms Inducing Apoptosis in Tumor Cells: A Promising Adjuvant in Cancer Therapy

Various literature data show how a diet rich in vegetables could reduce the incidence of several cancers due to the contribution of the natural polyphenols contained in them. Polyphenols are attributed multiple pharmacological actions such as anti-inflammatory, anti-oxidant, antibiotic, antiseptic, anti-allergic, cardioprotective and even anti-tumor properties. The multiple mechanisms involved in their anti-tumor action include signaling pathways modulation associated with cell proliferation, differentiation, migration, angiogenesis, metastasis and cell death. Since the dysregulation of death processes is involved in cancer etiopathology, the natural compounds able to kill cancer cells could be used as new anticancer agents. Apoptosis, a programmed form of cell death, is the most potent defense against cancer and the main mechanism used by both chemotherapy agents and polyphenols. The aim of this review is to provide an update of literature data on the apoptotic molecular mechanisms induced by some representative polyphenol family members in cancer cells. This aspect is particularly important because it may be useful in the design of new therapeutic strategies against cancer involving the polyphenols as adjuvants.

Exploration of the effect of Celastrol on protein targets in nasopharyngeal carcinoma: Network pharmacology, molecular docking and experimental evaluations

Background: Celastrol, an important extract of Tripterygium wilfordii, shows strong antitumor activity in a variety of tumors including nasopharyngeal carcinoma (NPC). However, little is known about its targets in NPC. We aimed to screen the key gene targets of Celastrol in the treatment of NPC by means of in silico analyses (including network pharmacology and molecular docking) and experimental evaluations. Methods: The main target genes of Celastrol and the genes related to NPC were obtained by retrieving the relevant biological databases, and the common targets were screened. Protein-protein interaction analysis was used to screen the hub genes. Then, a "compound-target-disease" network model was created and molecular docking was used to predict the binding of Celastrol to the candidate hub proteins. Afterward, the expression changes of the candidate genes under the administration of Celastrol were verified in vitro and in vivo. Results: Sixty genes common to Celastrol and NPC were screened out, which may be related to numerous biological processes such as cell proliferation, apoptosis, and tube development, and enriched in various pathways such as PI3K- Akt, EGFR tyrosine kinase inhibitor resistance, and Apoptosis. The tight binding ability of the candidate hub proteins (TNF, VEGFA, and IL6) to Celastrol was predicted by molecular docking [Docking energy: TNF, -6.08; VEGFA,-6.76; IL6,-6.91(kcal/mol)]. In vitro experiments showed that the expression of TNF and VEGFA decreased while the expression of IL6 increased in NPC cells (CNE2 and HONE1) treated with Celastrol. In vivo experiments suggested that Celastrol significantly reduced the weight and volume of the transplanted tumors in tumor-bearing mice in vivo. The expression of TNF, VEGFA, and IL6 in the transplanted tumor cells could be regulated by using Celastrol, and the expression trends were consistent with the in vitro model. Conclusion: Several gene targets have been filtered out as the core targets of Celastrol in the treatment of NPC, which might be involved in a variety of signaling pathways. Hence, Celastrol may exert its anti-NPC activity through multiple targets and multiple pathways, which will provide new clues for further research. Future experiments are warranted to validate the findings.

Role of STAT3 in the pathogenesis of nasopharyngeal carcinoma and its significance in anticancer therapy

Nasopharyngeal carcinoma (NPC) is a type of head and neck tumor with noticeable regional and ethnic differences. It is associated with Epstein-Barr virus infection and has a tendency for local and distant metastasis. NPC is also highly sensitive to radiotherapy and chemotherapy. Over 70% of patients present with locoregionally advanced disease, and distant metastasis is the primary reason for treatment failure. A signal transducer and activator of transcription 3 (STAT3) promotes NPC oncogenesis through mechanisms within cancerous cells and their interactions with the tumor microenvironment, which is critical in the initiation, progression, and metastasis of NPC. Further, p-STAT3 is strongly associated with advanced NPC. Recent research on STAT3 has focused on its expression at the center of various oncogenic pathways. Here, we discuss the role of STAT3 in NPC and its potential therapeutic inhibitors and analogs for the treatment and control of NPC.

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 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.

Gambogic acid suppresses nasopharyngeal carcinoma via rewiring molecular network of cancer malignancy and immunosurveillance

Nasopharyngeal carcinoma (NPC) is a malignant tumor highly prevalent in Southeast Asia. The distant metastasis and disease recurrence are still unsolved clinical problems. In recent years, traditional Chinese medicine (TCM) monomers have become significantly attractive due to their advantages. Using high throughput drug sensitivity screening, we identified gambogic acid (GA) as a common TCM monomer displaying multiple anti-NPC effects. GA could effectively inhibit the proliferation of low differentiated cells and highly metastatic cells in NPC via inducing apoptosis and G2/M cell cycle arrest. In addition, GA obviously repressed the abilities of cell clone, migration, invasion, angiogenesis and represented satisfied synergistic effects combined with chemotherapy. Importantly, we found the elevated immune checkpoint CD47 stimulated after chemotherapy was dramatically impaired by GA treatment. Mechanically, the network pharmacology analyses unraveled that the oncogenic signaling pathways including STATs were rewired by GA treatment. Taken together, our study reveals a molecular basis and provides a rationale for GA application as the treatment regime in NPC therapy in future.

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.

Chemoprotective and chemosensitizing effects of apigenin on cancer therapy

BACKGROUND

Therapeutic resistance to radiation and chemotherapy is one of the major obstacles in cancer treatment. Although synthetic radiosensitizers are pragmatic solution to enhance tumor sensitivity, they pose concerns of toxicity and non-specificity. In the last decades, scientists scrutinized novel plant-derived radiosensitizers and chemosensitizers, such as flavones, owing to their substantial physiological effects like low toxicity and non-mutagenic properties on the human cells. The combination therapy with apigenin is potential candidate in cancer therapeutics. This review explicates the combinatorial strategies involving apigenin to overcome drug resistance and boost the anti-cancer properties.

METHODS

We selected full-text English papers on international databases like PubMed, Web of Science, Google Scholar, Scopus, and ScienceDirect from 1972 up to 2020. The keywords included in the search were: Apigenin, Chemoprotective, Chemosensitizing, Side Effects, and Molecular Mechanisms.

RESULTS

In this review, we focused on combination therapy, particularly with apigenin augmenting the anti-cancer effects of chemo drugs on tumor cells, reduce their side effects, subdue drug resistance, and protect healthy cells. The reviewed research data implies that these co-therapies exhibited a synergistic effect on various cancer cells, where apigenin sensitized the chemo drug through different pathways including a significant reduction in overexpressed genes, AKT phosphorylation, NFκB, inhibition of Nrf2, overexpression of caspases, up-regulation of p53 and MAPK, compared to the monotherapies. Meanwhile, contrary to the chemo drugs alone, combined treatments significantly induced apoptosis in the treated cells.

CONCLUSION

Briefly, our analysis proposed that the combination therapies with apigenin could suppress the unwanted toxicity of chemotherapeutic agents. It is believed that these expedient results may pave the path for the development of drugs with a high therapeutic index. Nevertheless, human clinical trials are a prerequisite to consider the potential use of apigenin in the prevention and treatment of various cancers. Conclusively, the clinical trials to comprehend the role of apigenin as a chemoprotective agent are still in infancy.

lncRNA PVT1 promotes cetuximab resistance of head and neck squamous cell carcinoma cells by inhibiting miR-124-3p

BACKGROUND

Cetuximab has been widely used in the clinical treatment of head and neck squamous cell carcinoma (HNSCC). However, whether long non-coding RNA plasmacytoma variant translocation 1 (lncRNA PVT1) is correlated with cetuximab resistance remains unclear.

METHODS

Western blot and qRT-PCR were performed to quantify the levels of genes and proteins, respectively. Cell functions were measured using Cell Counting Kit-8 (CCK-8), Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL), and flow cytometry assays. The methylation level was tested using methylation-specific PCR (MSP).

RESULTS

PVT1 was upregulated and positively correlated with the poor prognosis of HNSCC. PVT1 overexpression markedly promoted the survival and weakened the cetuximab sensitivity of HNSCC cells, while miR-124-3p overexpression showed opposite effects. Mechanistically, the silence of PVT1 indirectly promoted miR-124-3p expression by reducing its promoter methylation. Importantly, miR-124-3p overexpression impeded the regulatory roles of PVT1 overexpression.

CONCLUSION

PVT1 decreased the sensitivity of HNSCC cells to cetuximab by enhancing methylation-mediated inhibition of miR-124-3p, which might provide a new insight for the cetuximab chemoresistance of HNSCC.

Research Progress in Flavonoids as Potential Anticancer Drug Including Synergy with Other Approaches

BACKGROUND

In chemotherapy for cancer, conventional drugs aim to target the rapidly growing and dividing cells at the early stages. However, at an advanced stage, cancer cells become less susceptible because of the multidrug resistance and the recruitment of alternative salvage pathways for their survival. Besides, owing to target non-selectivity, healthy proliferating cells also become vulnerable to the damage. The combination therapies offered using flavonoids to cure cancer not only exert an additive effect against cancer cells by targetting supplementary cell carnage pathways but also hampers the drug resistance mechanisms. Thus, the review aims to discuss the potential and pharmacokinetic limitations of flavonoids in cancer treatment. Further successful synergistic studies reported using flavonoids to treat cancer has been described along with potential drug delivery systems.

METHODS

A literature search was done by exploring various online databases like Pubmed, Scopus, and Google Scholar with the specific keywords like "Anticancer drugs", "flavonoids", "oncology research", and "pharmacokinetics".

RESULTS

Dietary phytochemicals, mainly flavonoids, hinder cell signalling responsible for multidrug resistance and cancer progression, primarily targeting cancer cells sparing normal cells. Such properties establish flavonoids as a potential candidate for synergistic therapy. However, due to low absorption and high metabolism rates, the bioavailability of flavonoids becomes a challenge. Such challenges may be overcome using novel approaches like derivatization, and single or co-delivery nano-complexes of flavonoids with conventional drugs. These new approaches may improve the pharmacokinetic and pharmacodynamic of flavonoids.

CONCLUSION

This review highlights the application of flavonoids as a potential anticancer phytochemical class in combination with known anti-cancer drugs/nanoparticles. It also discusses flavonoid's pharmacokinetics and pharmacodynamics issues and ways to overcome such issues. Moreover, it covers successful methodologies employed to establish flavonoids as a safe and effective phytochemical class for cancer treatment.

Drug-herb interactions between Scutellaria baicalensis and pharmaceutical drugs: Insights from experimental studies, mechanistic actions to clinical applications

Whilst the popular use of herbal medicine globally, it poses challenges in managing potential drug-herb interaction. There are two folds of the drug-herb interaction, a beneficial interaction that may improve therapeutic outcome and minimise the toxicity of drug desirably; by contrast, negative interaction may evoke unwanted clinical consequences, especially with drugs of narrow therapeutic index. Scutellaria baicalensis Georgi is one of the most popular medicinal plants used in Asian countries. It has been widely used for treating various diseases and conditions such as cancer, diabetes, inflammation, and oxidative stress. Studies on its extract and bioactive compounds have shown pharmacodynamic and pharmacokinetic interactions with a wide range of pharmaceutical drugs as evidenced by plenty of in vitro, in vivo and clinical studies. Notably, S. baicalensis and its bioactives including baicalein, baicalin and wogonin exhibited synergistic interactions with many pharmaceutical drugs to enhance their efficacy, reduce toxicity or overcome drug resistance to combat complex diseases such as cancer, diabetes and infectious diseases. On the other hand, S. baicalensis and its bioactives also affected the pharmacokinetic profile of many drugs in absorption, distribution, metabolism and elimination via the regulatory actions of the efflux pumps and cytochrome P450 enzymes. This review provides comprehensive references of the observed pharmacodynamic and pharmacokinetic drug interactions of Scutellaria baicalensis and its bioactives. We have elucidated the interaction with detailed mechanistic actions, identified the knowledge gaps for future research and potential clinical implications. Such knowledge is important for the practice of both conventional and complementary medicines, and it is essential to ensure the safe use of related herbal medicines. The review may be of great interest to practitioners, consumers, clinicians who require comprehensive information on the possible drug interactions with S. baicalensis and its bioactives.

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.

Extending the small-molecule similarity principle to all levels of biology with the Chemical Checker

Small molecules are usually compared by their chemical structure, but there is no unified analytic framework for representing and comparing their biological activity. We present the Chemical Checker (CC), which provides processed, harmonized and integrated bioactivity data on ~800,000 small molecules. The CC divides data into five levels of increasing complexity, from the chemical properties of compounds to their clinical outcomes. In between, it includes targets, off-targets, networks and cell-level information, such as omics data, growth inhibition and morphology. Bioactivity data are expressed in a vector format, extending the concept of chemical similarity to similarity between bioactivity signatures. We show how CC signatures can aid drug discovery tasks, including target identification and library characterization. We also demonstrate the discovery of compounds that reverse and mimic biological signatures of disease models and genetic perturbations in cases that could not be addressed using chemical information alone. Overall, the CC signatures facilitate the conversion of bioactivity data to a format that is readily amenable to machine learning methods.

Apigenin Protects Mouse Retina against Oxidative Damage by Regulating the Nrf2 Pathway and Autophagy

Oxidative stress is a critical factor in the pathology of age-related macular degeneration (AMD). Apigenin (AP) is a flavonoid with an outstanding antioxidant activity. We had previously observed that AP protected APRE-19 cells against oxidative injury in vitro. However, AP has poor water and fat solubility, which determines its low oral bioavailability. In this study, we prepared the solid dispersion of apigenin (AP-SD). The solubility and dissolution of AP-SD was significantly better than that of the original drug, so the oral bioavailability in rats was better than that of the original drug. Then, the effects of AP-SD on the retina of a model mouse with dry AMD were assessed by fundus autofluorescence (FAF), optical coherence tomography (OCT), and electron microscopy; the results revealed that AP-SD alleviated retinopathy. Further research found that AP-SD promoted the nuclear translocation of Nrf2 and increased expression levels of the Nrf2 and target genes HO-1 and NQO-1. AP-SD enhanced the activities of SOD and GSH-Px and decreased the levels of ROS and MDA. Furthermore, AP-SD upregulated the expressions of p62 and LC3II in an Nrf2-dependent manner. However, these effects of AP-SD were observed only in the retina of Nrf2 WT mice, not in Nrf2 KO mice. In addition, the therapeutic effect of AP-SD was dose dependent, and AP did not work. In conclusion, AP-SD significantly enhanced the bioavailability of the original drug and reduced retinal oxidative injury in the model mouse of dry AMD in vivo. The results of the underlying mechanism showed that AP-SD upregulated the expression of antioxidant enzymes through the Nrf2 pathway and upregulated autophagy, thus inhibiting retinal oxidative damage. AP-SD may be a potential compound for the treatment of dry AMD.

Phytochemicals in Cancer Treatment: From Preclinical Studies to Clinical Practice

Cancer is a severe health problem that continues to be a leading cause of death worldwide. Increasing knowledge of the molecular mechanisms underlying cancer progression has led to the development of a vast number of anticancer drugs. However, the use of chemically synthesized drugs has not significantly improved the overall survival rate over the past few decades. As a result, new strategies and novel chemoprevention agents are needed to complement current cancer therapies to improve efficiency. Naturally occurring compounds from plants known as phytochemicals, serve as vital resources for novel drugs and are also sources for cancer therapy. Some typical examples include taxol analogs, vinca alkaloids such as vincristine, vinblastine, and podophyllotoxin analogs. These phytochemicals often act via regulating molecular pathways which are implicated in growth and progression of cancer. The specific mechanisms include increasing antioxidant status, carcinogen inactivation, inhibiting proliferation, induction of cell cycle arrest and apoptosis; and regulation of the immune system. The primary objective of this review is to describe what we know to date of the active compounds in the natural products, along with their pharmacologic action and molecular or specific targets. Recent trends and gaps in phytochemical based anticancer drug discovery are also explored. The authors wish to expand the phytochemical research area not only for their scientific soundness but also for their potential druggability. Hence, the emphasis is given to information about anticancer phytochemicals which are evaluated at preclinical and clinical level.

Apigenin as an effective anticancer natural product: Spotlight on TRAIL, WNT/β-catenin, JAK-STAT pathways, and microRNAs

Wealth of information gleaned from decades of high-impact research work; scientists have disentangled the complicated web of versatile regulators that underlie cancer development and progression. Use of structural biology approaches and functional genomics have helped us to gain new insights into complex nature of cancer, and it is now clear that genetic/epigenetic mutations, overexpression of oncogenes, inactivation of tumor suppressors, loss of apoptosis, and versatility of protein binding partners have contributory roles in carcinogenesis and metastatic spread. It is becoming progressively more understandable that reprogramming of gene expression during and nontranscriptional changes during cancer development and progression are initiated and controlled by deregulated signal transduction cascades, all of which collectively create an incalculable complexity. Data obtained through preclinical and clinical trials revealed that alterations in the targeted oncogenes and other downstream, and parallel pathways played a central role in the development of resistance against different therapeutics. Phytochemicals have regained limelight, and different natural products are currently being tested for efficacy in preclinical studies. Apigenin, a plant-derived flavonoid has considerable pharmacological value and is reportedly involved in the regulation of different signaling cascades. In this review, we have attempted to summarize rapidly evolving understanding of molecular biologists and pharmacologists about the potential of apigenin in the regulation of deregulated signaling pathways in different cancers. We have emphasized on the regulation of WNT/β-catenin and janus kinase/signal transducers and activators of transcription (JAK-STAT) pathways. We also comprehensively discuss how apigenin restored apoptosis in tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-resistant cancers. The review also gives a snapshot of microRNAs (miRNAs) that regulate wide-ranging biological processes, and it is now clear that each miRNA can control hundreds of gene targets. Apigenin was noted to upregulate miR-520b and miR-101 in different cancers to inhibit tumor growth. Moreover, apigenin-induced apoptotic rate was significantly higher when used in combination with miR-423-5p inhibitors or miR-138 mimics. Better comprehension of linear and integrated signaling pathways will be helpful in effective therapeutic targeting of deregulated signaling pathways to inhibit/prevent cancer.