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.

Promising Approaches in Plant-Based Therapies for Thyroid Cancer: An Overview of In Vitro, In Vivo, and Clinical Trial Studies

Thyroid cancer, particularly undifferentiated tumors, poses a significant challenge due to its limited response to standard therapies. The incidence of thyroid cancer, predominantly differentiated carcinomas, is on the rise globally. Anaplastic thyroid carcinoma (ATC), though rare, is highly aggressive and challenging to treat. Therefore, this study aimed to collect data and explore alternative treatments, focusing on the efficacy of photodynamic therapy (PDT) combined with natural compounds as well as the potential role of phytochemicals, including quercetin, kaempferol, apigenin, genistein, daidzein, naringenin, hesperitin, anthocyanidins, epigallocatechin gallate (EGCG), resveratrol, ellagic acid, ferulic acid, caffeic acid, curcumin, saponins, ursolic acid, indole-3-carbinol (I3C), capsaicin, and piperine in thyroid cancer treatment. PDT, utilizing sensitizers activated by tumor-directed light, demonstrates promising specificity compared to traditional treatments. Combining PDT with natural photosensitizers, such as hypericin and genistein, enhances cytotoxicity against thyroid carcinoma cells. This literature review summarizes the current knowledge on phytochemicals and their anti-proliferative effects in in vitro and in vivo studies, emphasizing their effectiveness and mechanism of action as a novel therapeutic approach for thyroid cancers, especially those refractory to standard treatments.

Natural products for combating multidrug resistance in cancer

Cancer cells frequently develop resistance to chemotherapeutic therapies and targeted drugs, which has been a significant challenge in cancer management. With the growing advances in technologies in isolation and identification of natural products, the potential of natural products in combating cancer multidrug resistance has received substantial attention. Importantly, natural products can impact multiple targets, which can be valuable in overcoming drug resistance from different perspectives. In the current review, we will describe the well-established mechanisms underlying multidrug resistance, and introduce natural products that could target these multidrug resistant mechanisms. Specifically, we will discuss natural compounds such as curcumin, resveratrol, baicalein, chrysin and more, and their potential roles in combating multidrug resistance. This review article aims to provide a systematic summary of recent advances of natural products in combating cancer drug resistance, and will provide rationales for novel drug discovery.

Natural Flavonoid Apigenin, an Effective Agent Against Nervous System Cancers

Cancer is a serious public health concern worldwide, and nervous system (NS) cancers are among the most life-threatening malignancies. Efforts have been devoted to introduce natural anticancer agents with minimal side effects. Apigenin is an edible flavonoid that is abundantly found in many vegetables and fruits. Various pharmaceutical activities, including anti-inflammatory, antioxidative, antimicrobial, and anticancer effects have been reported for apigenin. This review provides insights into the therapeutic effects of apigenin and flavonoids with similar structure on glioblastoma and neuroblastoma. Current evidence indicates that apigenin has the unique ability to cross the blood-brain barrier, and its antioxidative, anti-inflammatory, neurogenic, and neuroprotective effects have made this flavonoid a great option for the treatment of neurodegenerative disorders. Meanwhile, apigenin has low toxicity on normal neuronal cells, while induces cytotoxicity on NS cancer cells via triggering several signal pathways and molecular targets. Anticancer effects of apigenin have been contributed to various mechanisms such as induction of cell cycle arrest and apoptosis, and inhibition of migration, invasion, and angiogenesis. Although apigenin is a promising pharmaceutical agent, its low bioavailability is an important issue that must be solved before introducing to clinic. Recently, nano-delivery of apigenin by liposomes and poly lactic-co-glycolide nanoparticles has greatly improved functionality of this agent. Hence, investigating pharmaceutical effects of apigenin-loaded nanocarriers on NS cancer cell lines and animal models is recommended for future studies.

Research progress of plant-derived natural products in thyroid carcinoma

Thyroid carcinoma (TC) is a prevalent malignancy of the endocrine system, with a notable rise in its detection rate in recent decades. The primary therapeutic approaches for TC now encompass thyroidectomy and radioactive iodine therapy, yielding favorable prognoses for the majority of patients. TC survivors may necessitate ongoing surveillance, remedial treatment, and thyroid hormone supplementation, while also enduring the adverse consequences of thyroid hormone fluctuations, surgical complications, or side effects linked to radioactive iodine administration, and encountering enduring physical, psychosocial, and economic hardships. In vitro and in vivo studies of natural products against TC are demonstrating the potential of these natural products as alternatives to the treatment of thyroid cancer. This therapy may offer greater convenience, affordability, and acceptability than traditional therapies. In the early screening of natural products, we mainly use a combination of database prediction and literature search. The pharmacological effects on TC of selected natural products (quercetin, genistein, apigenin, luteolin, chrysin, myricetin, resveratrol, curcumin and nobiletin), which hold promise for therapeutic applications in TC, are reviewed in detail in this article through most of the cell-level evidence, animal-level evidence, and a small amount of human-level evidence. In addition, this article explores possible issues, such as bioavailability, drug safety.

Radioiodine-refractory differentiated thyroid cancer: Molecular mechanisms and therapeutic strategies for radioiodine resistance

Radioiodine-refractory differentiated thyroid cancer (RAIR-DTC) is difficult to treat with radioactive iodine because of the absence of the sodium iodide transporter in the basement membrane of thyroid follicular cells for iodine uptake. This is usually due to the mutation or rearrangement of genes and the aberrant activation of signal pathways, which result in abnormal expression of thyroid-specific genes, leading to resistance of differentiated thyroid cancer cells to radioiodine therapy. Therefore, inhibiting the proliferation and growth of RAIR-DTC with multikinase inhibitors and other drugs or restoring its differentiation and then carrying out radioiodine therapy have become the first-line treatment strategies and main research directions. The drugs that regulate these kinases or signaling pathways have been studied in clinical and preclinical settings. In this review, we summarized the major gene mutations, gene rearrangements and abnormal activation of signaling pathways that led to radioiodine resistance of RAIR-DTC, as well as the medicine that have been tested in clinical and preclinical trials.

The Neurodevelopmental and Molecular Landscape of Medulloblastoma Subgroups: Current Targets and the Potential for Combined Therapies

Medulloblastoma is the most common malignant pediatric brain tumor and is associated with significant morbidity and mortality in the pediatric population. Despite the use of multiple therapeutic approaches consisting of surgical resection, craniospinal irradiation, and multiagent chemotherapy, the prognosis of many patients with medulloblastoma remains dismal. Additionally, the high doses of radiation and the chemotherapeutic agents used are associated with significant short- and long-term complications and adverse effects, most notably neurocognitive delay. Hence, there is an urgent need for the development and clinical integration of targeted treatment regimens with greater efficacy and superior safety profiles. Since the adoption of the molecular-based classification of medulloblastoma into wingless (WNT) activated, sonic hedgehog (SHH) activated, group 3, and group 4, research efforts have been directed towards unraveling the genetic, epigenetic, transcriptomic, and proteomic profiles of each subtype. This review aims to delineate the progress that has been made in characterizing the neurodevelopmental and molecular features of each medulloblastoma subtype. It further delves into the implications that these characteristics have on the development of subgroup-specific targeted therapeutic agents. Furthermore, it highlights potential future avenues for combining multiple agents or strategies in order to obtain augmented effects and evade the development of treatment resistance in tumors.

COVID-19 associated thyroid dysfunction and other comorbidities and its management using phytochemical-based therapeutics: a natural way

The present severe acute respiratory syndrome-2 (SARS-CoV-2) mediated Coronavirus pandemic (COVID-19) and post-COVID-19 complications affect human life drastically. Patients who have been cured of COVID-19 infection are now experiencing post-COVID-19 associated comorbidities, which have increased mortality rates. The SARS-CoV-2 infection distresses the lungs, kidneys, gastrointestinal tract, and various endocrine glands, including the thyroid. The emergence of variants which includes Omicron (B.1.1.529) and its lineages threaten the world severely. Among different therapeutic approaches, phytochemical-based therapeutics are not only cost-effective but also have lesser side effects. Recently a plethora of studies have shown the therapeutic efficacy of various phytochemicals for the treatment of COVID-19. Besides this, various phytochemicals have been found efficacious in treating several inflammatory diseases, including thyroid-related anomalies. The method of the phytochemical formulation is quick and facile and the raw materials for such herbal preparations are approved worldwide for human use against certain disease conditions. Owing to the advantages of phytochemicals, this review primarily discusses the COVID-19-related thyroid dysfunction and the role of key phytochemicals to deal with thyroid anomaly and post-COVID-19 complications. Further, this review shed light on the mechanism via which COVID-19 and its related complication affect organ function of the body, along with the mechanistic insight into the way by which phytochemicals could help to cure post-COVID-19 complications in thyroid patients. Considering the advantages offered by phytochemicals as a safer and cost-effective medication they can be potentially used to combat COVID-19-associated comorbidities.

The new insights into autophagy in thyroid cancer progression

In recent decades, the incidence of thyroid cancer keeps growing at a shocking rate, which has aroused increasing concerns worldwide. Autophagy is a fundamental and ubiquitous biological event conserved in mammals including humans. Basically, autophagy is a catabolic process that cellular components including small molecules and damaged organelles are degraded for recycle to meet the energy needs, especially under the extreme conditions. The dysregulated autophagy has indicated to be involved in thyroid cancer progression. The enhancement of autophagy can lead to autophagic cell death during the degradation while the produced energies can be utilized by the rest of the cancerous tissue, thus this influence could be bidirectional, which plays either a tumor-suppressive or oncogenic role. Accordingly, autophagy can be suppressed by therapeutic agents and is thus regarded as a drug target for thyroid cancer treatments. In the present review, a brief description of autophagy and roles of autophagy in tumor context are given. We have addressed summary of the mechanisms and functions of autophagy in thyroid cancer. Some potential autophagy-targeted treatments are also summarized. The aim of the review is linking autophagy to thyroid cancer, so as to develop novel approaches to better control cancer progression.

Flavonoids target different molecules of autophagic and metastatic pathways in cancer cells

Despite the success of cancer therapy, it has encountered a major obstacle due to the complicated nature of cancer, namely resistance. The recurrence and metastasis of cancer occur when anti-cancer therapeutic agents fail to eradicate all cancer cells. Cancer therapy aims to find the best agent that targets all cancer cells, including those sensitive or resistant to treatment. Flavonoids, natural products from our diet, show anti-cancer effects in different studies. They can inhibit metastasis and the recurrence of cancers. This review discusses metastasis, autophagy, anoikis in cancer cells, and their dynamic relationship. We present evidence that flavonoids can block metastasis and induce cell death in cancer cells. Our research suggests that flavonoids can serve as potential therapeutic agents in cancer therapy.

Effects of Dietary Phytochemicals on DNA Damage in Cancer Cells

With the increasing incidence of cancer worldwide, the prevention and treatment of cancer have garnered considerable scientific attention. Traditional chemotherapeutic drugs are highly toxic and associated with substantial side effects; therefore, there is an urgent need for developing new therapeutic agents. Dietary phytochemicals are important in tumor prevention and treatment because of their low toxicity and side effects at low concentrations; however, their exact mechanisms of action remain obscure. DNA damage is mainly caused by physical or chemical factors in the environment, such as ultraviolet light, alkylating agents and reactive oxygen species that cause changes in the DNA structure of cells. Several phytochemicals have been shown inhibit the occurrence and development of tumors by inducing DNA damage. This article reviews the advances in phytochemical research; particularly regarding the mechanisms related to DNA damage and provide a theoretical basis for future chemoprophylaxis research.

Calycosin induces autophagy and apoptosis via Sestrin2/AMPK/mTOR in human papillary thyroid cancer cells

Calycosin, one of small molecules derived from astragalus, has anti-tumor effects in various tumors. However, the effects of calycosin on papillary thyroid cancer (PTC) remain unclear. This study aimed to explore the anti-tumor ability of calycosin on human PTC and its potential mechanisms. The B-CPAP cells were treated with calycosin, then cell proliferation, apoptosis and invasiveness were measured by CCK8 assay, flow cytometry, wound healing and transwell invasion assay, respectively. The cells were also performed by whole transcriptome microarray bioinformatics analysis. Apoptosis and autophagy-related markers or proteins were measured by qRT-PCR or western blot. Sestrin2-mediated AMPK/mTOR pathways were determined by western blot. We found that calycosin inhibited migration and invasion of B-CPAP cells and induced apoptosis (Bax/Bcl-2) and autophagy (LC3II/I, Beclin1) of B-CPAP cells. Differential expressed genes were screened between the calycosin-treated cells and control (524 genes upregulated and 328 genes downregulated). The pathway enrichment suggested that the role of calycosin in B-CPAP cells is closely related to apoptosis-related genes and p70S6 Kinase. Transmission electron microscopy found an increase in autophagosomes in calycosin-treated cells. Sestrin2 in human PTC tissues and B-CPAP cells was lower than in normal thyroid tissues and cells. And the pharmacological effects of calycosin in PTC cells were related to Sestrin2 activation, increased p-AMPK and inhibited p-mTOR and p-p70S6Kinase; these alterations were reversed when silencing Sestrin2. In conclusion, calycosin has an inhibitory effect on PTC via promoting apoptosis and autophagy through the Sestrin2/AMPK/mTOR pathway.

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.

Flavonoids as Potential Antiviral Agents for Porcine Viruses

Flavonoids are types of natural substances with phenolic structures isolated from a variety of plants. Flavonoids have antioxidant, anti-inflammatory, anticancer, and antiviral activities. Although most of the research or applications of flavonoids are focused on human diseases, flavonoids also show potential applicability against porcine virus infection. This review focuses on the recent progress in antiviral mechanisms of potential flavonoids against the most common porcine viruses. The mechanism discussed in this paper may provide a theoretical basis for drug screening and application of natural flavonoid compounds and flavonoid-containing herbs to control porcine virus infection and guide the research and development of pig feed additives.

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.

Re-evaluation of the role of autophagy in thyroid cancer treatment

Numerous studies have examined the role of autophagy in thyroid cancer treatment; however there are discrepancies among the reported data, with some showing the pro-survival and others the anti-survival effects of autophagy. These discrepant results appear to be at least in part due to insufficient analyses or data misinterpretation as well as improper assessments of autophagic activity. Therefore, the present study re-evaluated the regulation of autophagic activity by various anticancer modalities and examined the role of autophagy in thyroid cancer treatment in three thyroid cancer cell lines (TPC1, ACT1 and KTC1). The immunofluorescence and DalGreen findings demonstrated that cisplatin, irradiation and sorafenib were all autophagy inducers as previously reported, but, unlike previous studies using thyroid cancer cells, doxorubicin acted as an inhibitor. KTC1 cells are unique because they only responded to cisplatin. The efficacy of anticancer therapeutics was significantly higher in chloroquine or 3-methyladenine-treated autophagy-defective cells than in autophagy-competent cells, thereby indicating the pro-survival effect of autophagy induced by anticancer therapeutics, which is partly due to inhibition of apoptosis. Thus, the present findings relating to several anticancer therapeutics and three thyroid cancer cell lines demonstrate the pro-survival effect of autophagy in thyroid cancer treatment. Although the present study only involved cell lines, it provides evidence for the beneficial combination of the anticancer therapeutic modalities with autophagy inhibitors, and proposes that autophagy inhibitors may serve as a possible adjunctive therapy for thyroid cancer.

Targeting Autophagy in Thyroid Cancer: EMT, Apoptosis, and Cancer Stem Cells

Autophagy is a highly conserved recycling process through which cellular homeostasis is achieved and maintained. With respect to cancer biology, autophagy acts as a double-edged sword supporting tumor cells during times of metabolic and therapeutic stress, while also inhibiting tumor development by promoting genomic stability. Accumulating evidence suggests that autophagy plays a role in thyroid cancer, acting to promote tumor cell viability and metastatic disease through maintenance of cancer stem cells (CSCs), supporting epithelial-to-mesenchymal transition (EMT), and preventing tumor cell death. Intriguingly, well-differentiated thyroid cancer is more prevalent in women as compared to men, though the underlying molecular biology driving this disparity has not yet been elucidated. Several studies have demonstrated that autophagy inhibitors may augment the anti-cancer effects of known thyroid cancer therapies. Autophagy modulation has become an attractive target for improving outcomes in thyroid cancer. This review aims to provide a comprehensive picture of the current knowledge regarding the role of autophagy in thyroid cancer, focusing on the potential mechanism(s) through which inhibition of autophagy may enhance cancer therapy and outcomes.

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.

Cinnamaldehyde induces autophagy-mediated cell death through ER stress and epigenetic modification in gastric cancer cells

Previous reports suggested that cinnamaldehyde (CA), the bioactive ingredient in Cinnamomum cassia, can suppress tumor growth, migratory, and invasive abilities. However, the role and molecular mechanisms of CA in GC are not completely understood. In the present study, we found that CA-induced ER stress and cell death via the PERK-CHOP axis and Ca²⁺ release in GC cells. Inhibition of ER stress using specific-siRNA blocked CA-induced cell death. Interestingly, CA treatment resulted in autophagic cell death by inducing Beclin-1, ATG5, and LC3B expression and by inhibiting p62 expression whereas autophagy inhibition suppressed CA-induced cell death. We showed that CA induces the inhibition of G9a and the activation of LC3B. Moreover, CA inhibited G9a binding on Beclin-1 and LC3B promoter. Overall, these results suggested that CA regulates the PERK-CHOP signaling, and G9a inhibition activates autophagic cell death via ER stress in GC cells.

Therapeutic potential of flavonoids in cancer: ROS-mediated mechanisms

Cancer is a leading cause of morbidity and mortality around the globe. Reactive oxygen species (ROS) play contradicting roles in cancer incidence and progression. Antioxidants have attracted attention as emerging therapeutic agents. Among these are flavonoids, which are natural polyphenols with established anticancer and antioxidant capacities. Increasing evidence shows that flavonoids can inhibit carcinogenesis via suppressing ROS levels. Surprisingly, flavonoids can also trigger excessive oxidative stress, but this can also induce death of malignant cells. In this review, we explore the inherent characteristics that contribute to the antioxidant capacity of flavonoids, and we dissect the scenarios in which they play the contrasting role as pro-oxidants. Furthermore, we elaborate on the pathways that link flavonoid-mediated modulation of ROS to the prevention and treatment of cancer. Special attention is given to the ROS-mediated anticancer functions that (-)-epigallocatechin gallate (EGCG), hesperetin, naringenin, quercetin, luteolin, and apigenin evoke in various cancers. We also delve into the structure-function relations that make flavonoids potent antioxidants. This review provides a detailed perspective that can be utilized in future experiments or trials that aim at utilizing flavonoids or verifying their efficacy for developing new pharmacologic agents. We support the argument that flavonoids are attractive candidates for cancer therapy.

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.

Curcumin induces autophagic cell death in human thyroid cancer cells

Curcumin, a polyphenolic compound, is a well-known anticancer agent, although its poor bioavailability remains a big concern. Recent studies suggest that autophagy-targeted therapy may be a useful adjunct treatment for patients with thyroid cancer. Curcumin acts as an autophagy inducer on many cancer cells. However, little is known about the exact role of curcumin on thyroid cancer cells. In the present study, curcumin significantly inhibited the growth of thyroid cancer cells. Autophagy was markedly induced by curcumin treatment as evidenced by an increase in LC3-II conversion, beclin-1 accumulation, p62 degradation as well as the increased formation of acidic vesicular organelles (AVOs). 3-MA, an autophagy inhibitor, partially rescued thyroid cancer cells from curcumin-induced cell death. Additionally, curcumin was found to exert selective cytotoxicity on thyroid cancer cells but not normal epithelial cells and acted as an autophagy inducer through activation of MAPK while inhibition of mTOR pathways. Hyperactivation of the AKT/mTOR axis was observed in the majority of PTC samples we tested, and thyroid cancer cell lines along with cancer tissue specimens sustained a low basal autophagic activity. Taken together, our results provide new evidence that inducing autophagic cell death may serve as a potential anti-cancer strategy to handle thyroid cancer.

Targeting Autophagy with Natural Products as a Potential Therapeutic Approach for Cancer

Macro-autophagy (autophagy) is a highly conserved eukaryotic intracellular process of self-digestion caused by lysosomes on demand, which is upregulated as a survival strategy upon exposure to various stressors, such as metabolic insults, cytotoxic drugs, and alcohol abuse. Paradoxically, autophagy dysfunction also contributes to cancer and aging. It is well known that regulating autophagy by targeting specific regulatory molecules in its machinery can modulate multiple disease processes. Therefore, autophagy represents a significant pharmacological target for drug development and therapeutic interventions in various diseases, including cancers. According to the framework of autophagy, the suppression or induction of autophagy can exert therapeutic properties through the promotion of cell death or cell survival, which are the two main events targeted by cancer therapies. Remarkably, natural products have attracted attention in the anticancer drug discovery field, because they are biologically friendly and have potential therapeutic effects. In this review, we summarize the up-to-date knowledge regarding natural products that can modulate autophagy in various cancers. These findings will provide a new position to exploit more natural compounds as potential novel anticancer drugs and will lead to a better understanding of molecular pathways by targeting the various autophagy stages of upcoming cancer therapeutics.

The Multifaceted Role of Flavonoids in Cancer Therapy: Leveraging Autophagy with a Double-Edged Sword

Flavonoids are considered as pleiotropic, safe, and readily obtainable molecules. A large number of recent studies have proposed that flavonoids have potential in the treatment of tumors by the modulation of autophagy. In many cases, flavonoids suppress cancer by stimulating excessive autophagy or impairing autophagy flux especially in apoptosis-resistant cancer cells. However, the anti-cancer activity of flavonoids may be attenuated due to the simultaneous induction of protective autophagy. Notably, flavonoids-triggered protective autophagy is becoming a trend for preventing cancer in the clinical setting or for protecting patients from conventional therapeutic side effects in normal tissues. In this review, focusing on the underlying autophagic mechanisms of flavonoids, we hope to provide a new perspective for clinical application of flavonoids in cancer therapy. In addition, we highlight new research ideas for the development of new dosage forms of flavonoids to improve their various pharmacological effects, establishing flavonoids as ideal candidates for cancer prevention and therapy in the clinic.

Phytochemicals in thyroid cancer: analysis of the preclinical studies

PURPOSE

In the search for novel effective compounds to use in thyroid cancer (TC) unresponsive to current treatment, attention has recently focused on plant-derived compounds with anticancer activity. In this review, we discuss the preclinical studies demonstrating phytochemical activity against thyroid cancer cells.

RESULTS/CONCLUSIONS

In particular, we describe their antiproliferative properties or ability to re-induce iodine retention, thus supporting their potential use as single agents or adjuvants in radioiodine-resistant thyroid cancer treatment.

Polyphenols of the Mediterranean Diet and Their Metabolites in the Prevention of Colorectal Cancer

The Mediterranean diet is a central element of a healthy lifestyle, where polyphenols play a key role due to their anti-oxidant properties, and for some of them, as nutripharmacological compounds capable of preventing a number of diseases, including cancer. Due to the high prevalence of intestinal cancer (ranking second in causing morbidity and mortality), this review is focused on the beneficial effects of selected dietary phytophenols, largely present in Mediterranean cooking: apigenin, curcumin, epigallocatechin gallate, quercetin-rutine, and resveratrol. The role of the Mediterranean diet in the prevention of colorectal cancer and future perspectives are discussed in terms of food polyphenol content, the effectiveness, the plasma level, and the importance of other factors, such as the polyphenol metabolites and the influence of the microbiome. Perspectives are discussed in terms of microbiome-dependency of the brain-second brain axis. The emergence of polyphenol formulations may strengthen the efficiency of the Mediterranean diet in the prevention of cancer.

V600EBRAF Inhibition Induces Cytoprotective Autophagy through AMPK in Thyroid Cancer Cells

The dysregulation of autophagy is important in the development of many cancers, including thyroid cancer, where ^V600EBRAF is a main oncogene. Here, we analyse the effect of ^V600EBRAF inhibition on autophagy, the mechanisms involved in this regulation and the role of autophagy in cell survival of thyroid cancer cells. We reveal that the inhibition of ^V600EBRAF activity with its specific inhibitor PLX4720 or the depletion of its expression by siRNA induces autophagy in thyroid tumour cells. We show that ^V600EBRAF downregulation increases LKB1-AMPK signalling and decreases mTOR activity through a MEK/ERK-dependent mechanism. Moreover, we demonstrate that PLX4720 activates ULK1 and increases autophagy through the activation of the AMPK-ULK1 pathway, but not by the inhibition of mTOR. In addition, we find that autophagy blockade decreases cell viability and sensitize thyroid cancer cells to ^V600EBRAF inhibition by PLX4720 treatment. Finally, we generate a thyroid xenograft model to demonstrate that autophagy inhibition synergistically enhances the anti-proliferative and pro-apoptotic effects of ^V600EBRAF inhibition in vivo. Collectively, we uncover a new role of AMPK in mediating the induction of cytoprotective autophagy by ^V600EBRAF inhibition. In addition, these data establish a rationale for designing an integrated therapy targeting ^V600EBRAF and the LKB1-AMPK-ULK1-autophagy axis for the treatment of ^V600EBRAF-positive thyroid tumours.

The Anticancer Potential of Apigenin Via Immunoregulation

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

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.

Autophagy: Mechanisms and Therapeutic Potential of Flavonoids in Cancer

Autophagy, which is a conserved biological process and essential mechanism in maintaining homeostasis and metabolic balance, enables cells to degrade cytoplasmic constituents through lysosomes, recycle nutrients, and survive during starvation. Autophagy exerts an anticarcinogenic role in normal cells and inhibits the malignant transformation of cells. On the other hand, aberrations in autophagy are involved in gene derangements, cell metabolism, the process of tumor immune surveillance, invasion and metastasis, and tumor drug-resistance. Therefore, autophagy-targeted drugs may function as anti-tumor agents. Accumulating evidence suggests that flavonoids have anticarcinogenic properties, including those relating to cellular proliferation inhibition, the induction of apoptosis, autophagy, necrosis, cell cycle arrest, senescence, the impairment of cell migration, invasion, tumor angiogenesis, and the reduction of multidrug resistance in tumor cells. Flavonoids, which are a group of natural polyphenolic compounds characterized by multiple targets that participate in multiple pathways, have been widely studied in different models for autophagy modulation. However, flavonoid-induced autophagy commonly interacts with other mechanisms, comprehensively influencing the anticancer effect. Accordingly, targeted autophagy may become the core mechanism of flavonoids in the treatment of tumors. This paper reviews the flavonoid-induced autophagy of tumor cells and their interaction with other mechanisms, so as to provide a comprehensive and in-depth account on how flavonoids exert tumor-suppressive effects through autophagy.

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.

Hegazy ME, Naqishbandi AM, Efferth T. Induction of Apoptosis, Autophagy and Ferroptosis by Thymus vulgaris and Arctium lappa Extract in Leukemia and Multiple Myeloma Cell Lines

Thymus vulgaris and Arctium lappa have been used as a folk remedy in the Iraqi Kurdistan region to deal with different health problems. The aim of the current study is to investigate the cytotoxicity of T. vulgaris and A. lappa in leukemia and multiple myeloma (MM) cell lines and determine the mode of cell death triggered by the most potent cytotoxic fractions of both plants in MM. Resazurin assay was used to evaluate cytotoxic and ferroptosis activity, apoptosis, and modulation in the cell cycle phase were investigated via Annexin V-FITC/PI dual stain and cell-cycle arrest assays. Furthermore, we used western blotting assay for the determination of autophagy cell death. n-Hexane, chloroform, ethyl acetate, and butanol fractions of T. vulgaris and A. lappa exhibited cytotoxicity in CCRF-CEM and CEM/ADR 5000 cell lines at concentration range 0.001–100 μg/mL with potential activity revealed by chloroform and ethyl acetate fractions. NCI-H929 displayed pronounced sensitivity towards T. vulgaris (TCF) and A. lappa (ACF) chloroform fractions with IC₅₀ values of 6.49 ± 1.48 and 21.9 ± 0.69 μg/mL, respectively. TCF induced apoptosis in NCI-H929 cells with a higher ratio (71%), compared to ACF (50%) at 4 × IC₅₀. ACF demonstrated more potent autophagy activity than TCF. TCF and ACF induced cell cycle arrest and ferroptosis. Apigenin and nobiletin were identified in TCF, while nobiletin, ursolic acid, and lupeol were the main compounds identified in ACF. T. vulgaris and A. lappa could be considered as potential herbal drug candidates, which arrest cancer cell proliferation by induction of apoptosis, autophagic, and ferroptosis.

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.

Polyphenol-Mediated Autophagy in Cancer: Evidence of In Vitro and In Vivo Studies

One of the hallmarks of cellular transformation is the altered mechanism of cell death. There are three main types of cell death, characterized by different morphological and biochemical features, namely apoptosis (type I), autophagic cell death (type II) and necrosis (type III). Autophagy, or self-eating, is a tightly regulated process involved in stress responses, and it is a lysosomal degradation process. The role of autophagy in cancer is controversial and has been associated with both the induction and the inhibition of tumor growth. Autophagy can exert tumor suppression through the degradation of oncogenic proteins, suppression of inflammation, chronic tissue damage and ultimately by preventing mutations and genetic instability. On the other hand, tumor cells activate autophagy for survival in cellular stress conditions. Thus, autophagy modulation could represent a promising therapeutic strategy for cancer. Several studies have shown that polyphenols, natural compounds found in foods and beverages of plant origin, can efficiently modulate autophagy in several types of cancer. In this review, we summarize the current knowledge on the effects of polyphenols on autophagy, highlighting the conceptual benefits or drawbacks and subtle cell-specific effects of polyphenols for envisioning future therapies employing polyphenols as chemoadjuvants.

Plant natural products with anti-thyroid cancer activity

Thyroid cancer is the most frequent endocrine malignancy, with more than 500,000 cases per year worldwide. Differentiated thyroid cancers are the most common forms with best prognosis, while poorly/undifferentiated ones are rare (2% of all thyroid cancer), aggressive, frequently metastasize and have a worse prognosis. For aggressive, metastatic and advanced thyroid cancer novel antitumor molecules are urgently needed and phytochemical products can be a rational and extensive source, since secondary plant metabolites can guarantee the necessary biochemical variability for therapeutic purpose. Among bioactive molecules that present biological activity on thyroid cancer, resveratrol, curcumin, isoflavones, glucosinolates are the most common and used in experimental model. Most of them have been studied both in vitro and in vivo on this cancer, but rarely in clinical trial. This review summarizes phytochemicals, phytotherapeutics and plant derived compounds used in thyroid cancer.

Apigenin Prevents Acetaminophen-Induced Liver Injury by Activating the SIRT1 Pathway

Acetaminophen (APAP) overdose is the main cause of acute liver failure. Apigenin (API) is a natural dietary flavonol with high antioxidant capacity. Herein, we investigated protection by API against APAP-induced liver injury in mice, and explored the potential mechanism. Cell viability assays and mice were used to evaluate the effects of API against APAP-induced liver injury. Western blotting, immunofluorescence staining, RT-PCR, and Transmission Electron Microscope were carried out to determine the signalling pathways affected by API. Analysis of mouse serum levels of alanine/aspartate aminotransferase (ALT/AST), malondialdehyde (MDA), liver myeloperoxidase (MPO) activity, glutathione (GSH), and reactive oxygen species (ROS) revealed that API (80 mg/kg) owned protective effect on APAP-induced liver injury. Meanwhile, API ameliorated the decreased cell viability in L-02 cells incubated by APAP with a dose dependent. Furthermore, API promoted SIRT1 expression and deacetylated p53. Western blotting showed that API promoted APAP-induced autophagy, activated the NRF2 pathway, and inhibited the transcriptional activation of nuclear p65 in the presence of APAP. Furthermore, SIRT1 inhibitor EX-527 reduced protection by API against APAP-induced hepatotoxicity. Molecular docking results indicate potential interaction between API and SIRT1. API prevents APAP-induced liver injury by regulating the SIRT1-p53 axis, thereby promoting APAP-induced autophagy and ameliorating APAP-induced inflammatory responses and oxidative stress injury.

Herbal Active Ingredients: An Emerging Potential for the Prevention and Treatment of Papillary Thyroid Carcinoma

Papillary thyroid carcinoma (PTC) is the most common subtype of differentiated thyroid cancers in Asian coastal cities, where the patients have increased risk of potentially high or excessive iodine intake. Given the high metastasis and recurrence of patients with BRAF^V600E mutation, the mortality rate of thyroid cancer has recently shown an upward trend. A variety of therapies, including surgery, radiotherapy, and chemotherapy, have been used to treat thyroid cancer, but these therapies still have limitations, including postoperative complications, drug resistance, poor efficacy, or serious side effects. Recent studies have shown the potential of active ingredients derived from herbal medicine in inhibiting PTC via various cell signaling pathways. Some plant-derived compounds, such as apigenin, genistein, and curcumin, are also known to prevent and treat PTC. This article summarizes the recent advances in the structure-functional impact of anti-PTC active ingredients and their effects on PTC cells and tumor microenvironments with an emphasis on their challenges from basic research to clinical practice.

Apigenin as an anticancer agent

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

Asparanin A from Asparagus officinalis L. Induces G0/G1 Cell Cycle Arrest and Apoptosis in Human Endometrial Carcinoma Ishikawa Cells via Mitochondrial and PI3K/AKT Signaling Pathways

Asparanin A (AA), a steroidal saponin from Asparagus officinalis L., has anticancer activity: however, its detailed molecular mechanisms in endometrial cancer (EC) have not been studied so far. We evaluated the anticancer activity and underlying mechanism of AA on EC cell line Ishikawa in vitro and in vivo. AA inhibited the Ishikawa cell proliferation and caused cell morphology alteration and cell cycle arrest in G0/G1 phase. Moreover, it could induce apoptosis through mitochondrial pathway, including the deregulation of Bak/Bcl-xl ratio which led to the generation of ROS, up-regulation of cytochrome c followed by decrease of Δψ_m, and activation of caspases, besides inhibition of the PI3K/AKT/mTOR pathway. In vivo data showed that administration of AA significantly inhibited the tumor tissue cell proliferation, reduced the tumor growth, and induced the apoptosis occurrence. AA can be a possible functional food ingredient to cure endometrial cancer followed by clinical trials.

Apigenin, A Plant Flavone Playing Noble Roles in Cancer Prevention Via Modulation of Key Cell Signaling Networks

Background:

Cancer is a global health problem and the continuous rise in incidence and mortality due to cancer carries a real economic burden to all countries. Accumulation of genetic mutation, exposure of environmental carcinogens and food habits due to change in lifestyles are the key reasons for cancer. Targeting cancer cells, we need a multitargeting molecule with low/no toxicity.

Objective :

To review the current update of the research status of chemopreventive/therapeutic molecule, Apigenin.

Methods:

Compare the results of the published articles and granted patents on this compound. We also discuss the pros and cons of the present research and future direction.

Results:

Cancer cells have characteristic alterations and dysregulation of various cell signaling pathways that control cell homeostasis, proliferation, motility, and survival in normal cells. Natural flavonoids are the compounds well known for their anti-inflammatory, anti-oxidant, and anti-cancerous properties. Apigenin, along with several other physiological effects, has a very low intrinsic toxicity and striking effects on the proliferation of cancer cells. Interestingly, this multitargeting molecule is getting wide acceptance among researchers. It is evident from the recent patents filed in this compound. At present, three patents have been granted only on the anticancer properties of apigenin.

Conclusion:

This mini-review will explain the present research status of apigenin and will further shine some light on how apigenin performs its anti-cancerous actions by interfering with the key cellsignaling pathways.

Depletion of VAX2 Restrains the Malignant Progression of Papillary Thyroid Carcinoma by Modulating ERK Signaling Pathway

Objective

Ventral anterior homeobox 2 (VAX2) gene is a key regulating factor for the development of the ventral region of the eye, and has recently attracted much attention from the cancer treatment field. Our study aimed to explore the effect of VAX2 on papillary thyroid carcinoma (PTC).

Methods

We determined the expression levels of VAX2 in PTC based on The Cancer Genome Atlas (TCGA) database. We then assessed the prognosis of patients with PTC, and analyzed the association between VAX2 expression and clinicopathological characteristics. Subsequently, we measured the biological functions of VAX2 in PTC using qRT-PCR, cell counting kit-8 (CCK-8) assay, colony formation assay, wound healing assay, transwell assays and western blot.

Results

VAX2 was up-regulated in PTC tissues when compared with normal thyroid tissues, and high expression level of VAX2 was positively correlated with poor prognosis. Furthermore, knockdown of VAX2 significantly inhibited the proliferation, migration and invasion of PTC cells. Importantly, through western blot analysis, we found that the expression of phosphorylated-(p) ERK and p-MEK in ERK signaling pathway showed a significant decrease after knockdown of VAX2.

Conclusion

These findings suggest that VAX2 may be involved in the malignant progression of PTC, and hold significant potential as a therapeutic target for PTC.

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

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

Apigenin restores impairment of autophagy and downregulation of unfolded protein response regulatory proteins in keratinocytes exposed to ultraviolet B radiation

Ultraviolet (UV)-B radiation is a major environmental risk factor that is responsible for the development and progression of many skin cancers. Apigenin, a type of bioflavonoid, has been reported to inhibit UVB-induced skin cancer. However, how apigenin functions in keratinocytes with UV damage remains unclear. In this study, by lactate dehydrogenase (LDH) release assay, we found that apigenin treatment increased cell death in the primary human epidermal keratinocytes (HEKs) and the cutaneous squamous cell carcinoma cell line COLO-16. Apigenin treatment reduced microtubule-associated protein 1 light chain 3 (LC3)-II turnover, acridine orange staining and GFP-LC3 puncta in both cell types, suggesting autophagy inhibition. However, apigenin treatment restored the inhibition of autophagy in UVB-challenged HEKs. Moreover, apigenin treatment restored the UVB-induced downregulation of ataxia-telangiectasia mutated (ATM), ataxia-telangiectasia, Rad3-related (ATR) and the unfolded protein response (UPR) regulatory proteins, BiP, IRE1α and PERK in HEKs. Apigenin treatment also inhibited UVB-induced apoptosis and cell death in HEKs. In addition, autophagy inhibition by autophagy-related gene (ATG) 5 RNA interference interrupted apigenin-induced restoration of ATR, ATM and BiP, which were downregulated in HEKs exposed to UVB radiation. Our findings indicate that apigenin exhibits a novel protective effect in keratinocytes with UVB damage, suggesting potential application as a photoprotective agent.

Antitumor Effect of Various Phytochemicals on Diverse Types of Thyroid Cancers

Thyroid cancers developed from the tissues of the thyroid gland are classified into papillary (PTC), follicular (FTC), medullary (MTC), and anaplastic thyroid cancer (ATC). Although thyroid cancers have been generally known as mild forms of cancer, undifferentiated MTC and ATC have a more unfavorable prognosis than differentiated PTC and FTC because they are more aggressive and early metastatic. A variety of therapies such as surgery, radiotherapy, and chemotherapy have been currently used to treat thyroid cancer, but they still have limitations including drug resistance or unfavorable side effects. Phytochemicals are plant-derived chemicals having various physiological activities that are expected to be effective in cancer treatment. In this review, anticancer efficacy of phytochemicals, such as resveratrol, genistein, curcumin, and other substances in each type of thyroid cancer was introduced with their chemopreventive mechanisms. English articles related with thyroid cancer and anti-thyroid cancer of phytochemicals were searched from PubMed and Google Scholar. This article mainly focused on in vitro or animal studies on phytochemicals with anti-thyroid cancer activity. These various phytochemicals have been shown to induce apoptosis in all types of thyroid cancer cells, inhibit cell proliferation and invasion, and to be helpful in enhancing the effect of radioiodine therapy that is a typical therapy to thyroid cancer. These results suggest that thyroid cancer can be more effectively treated by the combinations of phytochemicals and the existing therapies or substances.

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.

Analysis of proautophagic activities of Citrus flavonoids in liver cells reveals the superiority of a natural polyphenol mixture over pure flavones

Autophagy dysfunction has been implicated in the pathogenesis of nonalcoholic fatty liver disease (NAFLD). Natural compounds present in bergamot polyphenol fraction (BPF) prevent NAFLD and induce autophagy in rat livers. Here, we employed HepG2 cells expressing DsRed-LC3-GFP, a highly sensitive model system to screen for proautophagic compounds present in BPF. BPF induced autophagy in a time- and dose-dependent fashion and the effect was amplified in cells loaded with palmitic acid. Autophagy was mediated by the hydrophobic fraction of acid-hydrolyzed BPF (A-BPF), containing six flavanone and flavone aglycones as identified by liquid chromatography-high-resolution mass spectrometry. Among them, naringenin, hesperitin, eriodictyol and diosmetin were weak inducers of autophagy. Apigenin showed the strongest and dose-dependent proautophagic activity at early time points (6 h). Luteolin induced a biphasic autophagic response, strong at low doses and inhibitory at higher doses. Both flavones were toxic in HepG2 cells and in differentiated human liver progenitors HepaRG upon longer treatments (24 h). In contrast, BPF and A-BPF did not show any toxicity, but induced a persistent increase in autophagic flux. A mixture of six synthetic aglycones mimicking A-BPF was sufficient to induce a similar autophagic response, but it was mildly cytotoxic. Thus, while six main BPF flavonoids fully account for its proautophagic activity, their combined effect is not sufficient to abrogate cytotoxicity of individual compounds. This suggests that a natural polyphenol phytocomplex, such as BPF, is a safer and more effective strategy for the treatment of NAFLD than the use of pure flavonoids.

Measurement of metabolite variations and analysis of related gene expression in Chinese liquorice (Glycyrrhiza uralensis) plants under UV-B irradiation

Plants respond to UV-B irradiation (280–315 nm wavelength) via elaborate metabolic regulatory mechanisms that help them adapt to this stress. To investigate the metabolic response of the medicinal herb Chinese liquorice (Glycyrrhiza uralensis) to UV-B irradiation, we performed liquid chromatography tandem mass spectrometry (LC-MS/MS)-based metabolomic analysis, combined with analysis of differentially expressed genes in the leaves of plants exposed to UV-B irradiation at various time points. Fifty-four metabolites, primarily amino acids and flavonoids, exhibited changes in levels after the UV-B treatment. The amino acid metabolism was altered by UV-B irradiation: the Asp family pathway was activated and closely correlated to Glu. Some amino acids appeared to be converted into antioxidants such as γ-aminobutyric acid and glutathione. Hierarchical clustering analysis revealed that various flavonoids with characteristic groups were induced by UV-B. In particular, the levels of some ortho-dihydroxylated B-ring flavonoids, which might function as scavengers of reactive oxygen species, increased in response to UV-B treatment. In general, unigenes encoding key enzymes involved in amino acid metabolism and flavonoid biosynthesis were upregulated by UV-B irradiation. These findings lay the foundation for further analysis of the mechanism underlying the response of G. uralensis to UV-B irradiation.

Apigenin's anticancer properties and molecular mechanisms of action: Recent advances and future prospectives

Cancer is a major health concern and leading burden on economy worldwide. An increasing effort is devoted to isolation and development of plant-derived dietary components as effective chemo-preventive products. Phytochemical compounds from natural resources such as fruits and vegetables are responsible for decreasing the risk of certain cancers among the consuming populations. Apigenin, a flavonoid phytochemical found in many kinds of fruits and vegetables, has been shown to exert significant biological effects, such as anti-oxidant, anti-inflammatory and most particularly anti-neoplastic properties. This review is intended to summarize the most recent advances in the anti-proliferative and chemo-preventive effects of apigenin in different cancer models. Analysis of the data from the studied cancer models has revealed that apigenin exerts its anti-proliferative effects through multiple and complex pathways. This guided us to discover some controversial results about the exact role of certain molecular pathways such as autophagy in the anticancer effects of apigenin. Further, there were cumulative positive evidences supporting the involvement of certain pathways such as apoptosis, ROS and DNA damage and repair. Apigenin possesses a high potential to be used as a chemosensitizing agent through the up-regulation of DR5 pathway. According to these preclinical findings we recommend that further robust unbiased studies should consider the possible interactions between different molecular pathways.