Involvement of ROS in Curcumin-induced Autophagic Cell Death

Novel curcumin derivatives N17 exert anti-cancer effects through the CSNK1G3/AKT axis in triple-negative breast cancer

Curcumin, extracted from Zingiberaceae and Araceae rhizomes, is clinically used for its anti-inflammatory, antibacterial, antioxidant, and anti-cancer properties. Its safety and potential make it a promising base for designing enhanced derivatives. The focus now is on optimizing curcumin and synthesizing more potent 1,4-pentadien-3-ones, which have anti-cancer activities. In the realm of triple-negative breast cancer (TNBC), an aggressive and invasive form with high metastatic potential, the need for innovative treatments is acute. The challenges posed by chemotherapy resistance, recurrence, and TNBC's heterogeneity have emphasized the necessity for novel therapeutic approaches. Our strategy involved the integration of a quinoxaline ring into 1,4-pentadien-3-one, followed by subsequent modifications. In this study, N17 demonstrated the ability to induce cell death and effectively suppress cell proliferation in breast cancer cells. These observed anti-cancer effects were attributed to the inhibition of p-AKT(S473), a key regulator implicated in both cell apoptosis and the modulation of epithelial-mesenchymal transition process in breast cancer cells. Furthermore, our investigation indicated N17 achieves its inhibitory effects on p-AKT(S473) by specifically targeting the CSNK1G3 protein. Remarkably, N17 not only impedes the EMT process but also triggers apoptosis through the CSNK1G3/AKT signaling axis. These findings provide the critical role of CSNK1G3 as an anti-cancer regulator in TNBC, establishing N17 as a pharmacological intervention with immense promise for treating cancer metastasis.

Targeting Peroxisome Proliferator-Activated Receptor-β/δ, Reactive Oxygen Species and Redox Signaling with Phytocompounds for Cancer Therapy

Significance: Peroxisome proliferator-activated receptors (PPARs) have a moderately preserved amino-terminal domain, an extremely preserved DNA-binding domain, an integral hinge region, and a distinct ligand-binding domain that are frequently encountered with the other nuclear receptors. PPAR-β/δ is among the three nuclear receptor superfamily members in the PPAR group. Recent Advances: Emerging studies provide an insight on natural compounds that have gained increasing attention as potential anticancer agents due to their ability to target multiple pathways involved in cancer development and progression. Critical Issues: Modulation of PPAR-β/δ activity has been suggested as a potential therapeutic strategy for cancer management. This review focuses on the ability of bioactive phytocompounds to impact reactive oxygen species (ROS) and redox signaling by targeting PPAR-β/δ for cancer therapy. The rise of ROS in cancer cells may play an important part in the initiation and progression of cancer. However, excessive levels of ROS stress can also be toxic to the cells and cancer cells with increased oxidative stress are likely to be more vulnerable to damage by further ROS insults induced by exogenous agents, such as phytocompounds and therapeutic agents. Therefore, redox modulation is a way to selectively kill cancer cells without causing significant toxicity to normal cells. However, use of antioxidants together with cancer drugs may risk the effect of treatment as both act through opposite mechanisms. Future Directions: It is advisable to employ more thorough and detailed methodologies to undertake mechanistic explorations of numerous phytocompounds. Moreover, conducting additional clinical studies is recommended to establish optimal dosages, efficacy, and the impact of different phytochemicals on PPAR-β/δ.

Sesquilignans PD from Zanthoxylum nitidum var. tomentosum exerts antitumor effects via the ROS/MAPK pathway in liver cancer cells

Sesquilignans PD is a natural phenylpropanoid compound that was isolated from Zanthoxylum nitidum var. tomentosum. In this study, we assessed the antitumor effect of PD on SK-Hep-1 and HepG2 cells and the underlying molecular mechanisms. The results revealed that PD markedly inhibited the proliferation and migration of both liver cancer cells. Moreover, PD induced apoptosis, autophagy, and reactive oxygen species (ROS) production in liver cancer cells. Notably, PD increased the protein levels of p-p38 MAPK and p-ERK1/2 in liver cancer cells. This is the first report on the anticancer effect of PD, which is mediated via increased ROS production and MAPK signaling activation.

Curcumin and its anti-colorectal cancer potential: From mechanisms of action to autophagy

Colorectal cancer (CRC) development and progression, one of the most common cancers globally, is supported by specific mechanisms to escape cell death despite chemotherapy, including cellular autophagy. Autophagy is an evolutionarily highly conserved degradation pathway involved in a variety of cellular processes, such as the maintenance of cellular homeostasis and clearance of foreign bodies, and its imbalance is associated with many diseases. However, the role of autophagy in CRC progression remains controversial, as it has a dual function, affecting either cell death or survival, and is associated with cellular senescence in tumor therapy. Indeed, numerous data have been presented that autophagy in cancers serves as an alternative to cell apoptosis when the latter is ineffective or in apoptosis-resistant cells, which is why it is also referred to as programmed cell death type II. Curcumin, one of the active constituents of Curcuma longa, has great potential to combat CRC by influencing various cellular signaling pathways and epigenetic regulation in a safe and cost-effective approach. This review discusses the efficacy of curcumin against CRC in vitro and in vivo, particularly its modulation of autophagy and apoptosis in various cellular pathways. While clinical studies have assessed the potential of curcumin in cancer prevention and treatment, none have specifically examined its role in autophagy. Nonetheless, we offer an overview of potential correlations to support the use of this polyphenol as a prophylactic or co-therapeutic agent in CRC.

Regulatory mechanism of perinatal nonylphenol exposure on cardiac mitochondrial autophagy and the PINK1/Parkin signaling pathway in male offspring rats

OBJECTIVE

This study investigated whether perinatal exposure to nonylphenol (NP) induces mitochondrial autophagy (i.e., mitophagy) damage in neonatal rat cardiomyocytes (NRCMs) and whether the PINK1/Parkin signaling pathway is involved in NP-induced primary cardiomyocyte injury.

METHODS AND RESULTS

In vivo: Perinatal NP exposure increased apoptosis and mitochondrial damage in NRCMs. Mitochondrial swelling and autophagosome-like structures with multiple concentric membranes were observed in the 100 mg/kg NP group, with an increase in the number of autophagosomes. Disorganized fiber arrangement and elevated serum myocardial enzyme levels were observed with increasing NP dosage. Additionally, NP exposure led to increased MDA levels and decreased SOD activity and ATP levels in myocardial tissue. The mRNA expression levels of autophagy-related genes, including Beclin-1, p62, and LC3B, as well as the expression of mitochondrial autophagy-related proteins (PINK1, p-Parkin, Parkin, Beclin-1, p62, LC3-I, LC3-II, and LC3-II/I) and apoptosis-related proteins (Bax and caspase-3), increased, whereas the expression levels of the mitochondrial membrane protein TOMM20 and the anti-apoptotic protein Bcl-2 decreased. In vitro: NP increased ROS levels, LDH release, and decreased ATP levels in NRCMs. CsA treatment significantly inhibited the expression of autophagy-related proteins (Beclin-1, LC3-II/I, and p62) and apoptosis-related proteins (caspase-3 and Bax), increased the expression levels of TOMM20 and Bcl-2 proteins, increased cellular ATP levels, and inhibited LDH release. The inhibition of the PINK1/Parkin signaling pathway suppressed the expression of mitochondrial autophagy-related proteins (PINK1, p-Parkin, Parkin, Beclin-1, LC3-II/I, and p62) and apoptosis-related proteins (caspase-3 and Bax), increased TOMM20 and Bcl-2 protein expression, increased ATP levels, and decreased LDH levels in NRCMs.

CONCLUSIONS

This study is novel in reporting that perinatal NP exposure induced myocardial injury in male neonatal rats, thereby inducing mitophagy. The PINK1/Parkin signaling pathway was involved in this injury by regulating mitophagy.

Targeted therapies of curcumin focus on its therapeutic benefits in cancers and human health: Molecular signaling pathway-based approaches and future perspectives

The curry powder spices turmeric (Curcuma longa L.), which contains curcumin (diferuloylmethane), an orange-yellow chemical. Polyphenols are the most commonly used sources of curcumin. It combats oxidative stress and inflammation in diseases, such as hyperlipidemia, metabolic syndrome, arthritis, and depression. Most of these benefits are due to their anti-inflammatory and antioxidant properties. Curcumin consumption leads to decreased bioavailability, resulting in limited absorption, quick metabolism, and quick excretion, which hinders health improvement. Numerous factors can increase its bioavailability. Piperine enhances bioavailability when combined with curcumin in a complex. When combined with other enhancing agents, curcumin has a wide spectrum of health benefits. This review evaluates the therapeutic potential of curcumin with a specific emphasis on its approach based on molecular signaling pathways. This study investigated its influence on the progression of cancer, inflammation, and many health-related mechanisms, such as cell proliferation, apoptosis, and metastasis. Curcumin has a significant potential for the prevention and treatment of various diseases. Curcumin modulates several biochemical pathways and targets involved in cancer growth. Despite its limited tissue accumulation and bioavailability when administered orally, curcumin has proven useful. This review provides an in-depth analysis of curcumin's therapeutic applications, its molecular signaling pathway-based approach, and its potential for precision medicine in cancer and human health.

Curcumin Enhances the Anticancer Effects of Binimetinib on Melanoma Cells by Inducing Mitochondrial Dysfunction and Cell Apoptosis with Necroptosis

BACKGROUND

Recent studies suggest that MEK1/2 inhibitors, including binimetinib, significantly improve malignant melanoma (MM) patient survival. Growing evidence suggests that phytochemicals, especially curcumin, can overcome drug resistance in cancer cells through a variety of mechanisms.

OBJECTIVE

This study aims to examine curcumin's efficacy in vitro combined with binimetinib in human MM cells.

METHODS

We used 2D monolayer and 3D spheroid human epidermal melanocyte culture models, HEMn-MP (human epidermal melanocytes, neonatal, moderately pigmented), and two human MM cell lines, G361 and SK-MEL-2, to evaluate cell viability, proliferation, migration, death, and reactive oxygen species (ROS) production following single therapy treatment, with either curcumin or binimetinib, or a combination of both.

RESULTS

Compared to MM cells treated with single therapy, those with combination therapy showed significantly decreased cell viability and increased ROS production. We observed apoptosis following both single and combination therapies. However only those who had had combination therapy had necroptosis.

CONCLUSION

Collectively, our data demonstrates that curcumin exerts significant synergistic anticancer effects on MM cells by inducing ROS and necroptosis when combined with binimetinib. Therefore, a strategy of adding curcumin to conventional anticancer agents holds promise for treating MM.

Natural Compounds Targeting the Autophagy Pathway in the Treatment of Colorectal Cancer

Autophagy is a highly conserved intracellular degradation pathway by which misfolded proteins or damaged organelles are delivered in a double-membrane vacuolar vesicle and finally degraded by lysosomes. The risk of colorectal cancer (CRC) is high, and there is growing evidence that autophagy plays a critical role in regulating the initiation and metastasis of CRC; however, whether autophagy promotes or suppresses tumor progression is still controversial. Many natural compounds have been reported to exert anticancer effects or enhance current clinical therapies by modulating autophagy. Here, we discuss recent advancements in the molecular mechanisms of autophagy in regulating CRC. We also highlight the research on natural compounds that are particularly promising autophagy modulators for CRC treatment with clinical evidence. Overall, this review illustrates the importance of autophagy in CRC and provides perspectives for these natural autophagy regulators as new therapeutic candidates for CRC drug development.

Autophagic mechanisms in longevity intervention: role of natural active compounds

The term 'autophagy' literally translates to 'self-eating' and alterations to autophagy have been identified as one of the several molecular changes that occur with aging in a variety of species. Autophagy and aging, have a complicated and multifaceted relationship that has recently come to light thanks to breakthroughs in our understanding of the various substrates of autophagy on tissue homoeostasis. Several studies have been conducted to reveal the relationship between autophagy and age-related diseases. The present review looks at a few new aspects of autophagy and speculates on how they might be connected to both aging and the onset and progression of disease. Additionally, we go over the most recent preclinical data supporting the use of autophagy modulators as age-related illnesses including cancer, cardiovascular and neurodegenerative diseases, and metabolic dysfunction. It is crucial to discover important targets in the autophagy pathway in order to create innovative therapies that effectively target autophagy. Natural products have pharmacological properties that can be therapeutically advantageous for the treatment of several diseases and they also serve as valuable sources of inspiration for the development of possible new small-molecule drugs. Indeed, recent scientific studies have shown that several natural products including alkaloids, terpenoids, steroids, and phenolics, have the ability to alter a number of important autophagic signalling pathways and exert therapeutic effects, thus, a wide range of potential targets in various stages of autophagy have been discovered. In this review, we summarised the naturally occurring active compounds that may control the autophagic signalling pathways.

Surveying the landscape of emerging and understudied cell death mechanisms

Cell death can be a highly regulated process. A large and growing number of mammalian cell death mechanisms have been described over the past few decades. Major pathways with established roles in normal or disease biology include apoptosis, necroptosis, pyroptosis and ferroptosis. However, additional non-apoptotic cell death mechanisms with unique morphological, genetic, and biochemical features have also been described. These mechanisms may play highly specialized physiological roles or only become activated in response to specific lethal stimuli or conditions. Understanding the nature of these emerging and understudied mechanisms may provide new insight into cell death biology and suggest new treatments for diseases such as cancer and neurodegeneration.

Targeting the Interplay of Autophagy and ROS for Cancer Therapy: An Updated Overview on Phytochemicals

Autophagy is an evolutionarily conserved self-degradation system that recycles cellular components and damaged organelles, which is critical for the maintenance of cellular homeostasis. Intracellular reactive oxygen species (ROS) are short-lived molecules containing unpaired electrons that are formed by the partial reduction of molecular oxygen. It is widely known that autophagy and ROS can regulate each other to influence the progression of cancer. Recently, due to the wide potent anti-cancer effects with minimal side effects, phytochemicals, especially those that can modulate ROS and autophagy, have attracted great interest of researchers. In this review, we afford an overview of the complex regulatory relationship between autophagy and ROS in cancer, with an emphasis on phytochemicals that regulate ROS and autophagy for cancer therapy. We also discuss the effects of ROS/autophagy inhibitors on the anti-cancer effects of phytochemicals, and the challenges associated with harnessing the regulation potential on ROS and autophagy of phytochemicals for cancer therapy.

Autophagy-Modulated Biomaterial: A Robust Weapon for Modulating the Wound Environment to Promote Skin Wound Healing

Autophagy, a self-renewal mechanism, can help to maintain the stability of the intracellular environment of organisms. Autophagy can also regulate several cellular functions and is strongly related to the onset and progression of several diseases. Wound healing is a biological process that is coregulated by different types of cells. However, it is troublesome owing to prolonged treatment duration and poor recovery. In recent years, biomaterials have been reported to influence the skin wound healing process by finely regulating autophagy. Biomaterials that regulate autophagy in various cells involved in skin wound healing to regulate the differentiation, proliferation and migration of cells, inflammatory responses, oxidative stress and formation of the extracellular matrix (ECM) have emerged as a key method for improving the tissue regeneration ability of biomaterials. During the inflammatory phase, autophagy enhances the clearance of pathogens from the wound site and leads to macrophage polarization from the M1 to the M2 phenotype, thus preventing enhanced inflammation that can lead to further tissue damage. Autophagy plays important roles in facilitating the formation of extracellular matrix (ECM) during the proliferative phase, removing excess intracellular ROS, and promoting the proliferation and differentiation of endothelial cells, fibroblasts, and keratinocytes. This review summarizes the close association between autophagy and skin wound healing and discusses the role of biomaterial-based autophagy in tissue regeneration. The applications of recent biomaterials designed to target autophagy are highlighted, including polymeric materials, cellular materials, metal nanomaterials, and carbon-based materials. A better understanding of biomaterial-regulated autophagy and skin regeneration and the underlying molecular mechanisms may open new possibilities for promoting skin regeneration. Moreover, this can lay the foundation for the development of more effective therapeutic approaches and novel biomaterials for clinical applications.

New Visions on Natural Products and Cancer Therapy: Autophagy and Related Regulatory Pathways

Macroautophagy (autophagy) has been a highly conserved process throughout evolution and allows cells to degrade aggregated/misfolded proteins, dysfunctional or superfluous organelles and damaged macromolecules, in order to recycle them for biosynthetic and/or energetic purposes to preserve cellular homeostasis and health. Changes in autophagy are indeed correlated with several pathological disorders such as neurodegenerative and cardiovascular diseases, infections, cancer and inflammatory diseases. Conversely, autophagy controls both apoptosis and the unfolded protein response (UPR) in the cells. Therefore, any changes in the autophagy pathway will affect both the UPR and apoptosis. Recent evidence has shown that several natural products can modulate (induce or inhibit) the autophagy pathway. Natural products may target different regulatory components of the autophagy pathway, including specific kinases or phosphatases. In this review, we evaluated ~100 natural compounds and plant species and their impact on different types of cancers via the autophagy pathway. We also discuss the impact of these compounds on the UPR and apoptosis via the autophagy pathway. A multitude of preclinical findings have shown the function of botanicals in regulating cell autophagy and its potential impact on cancer therapy; however, the number of related clinical trials to date remains low. In this regard, further pre-clinical and clinical studies are warranted to better clarify the utility of natural compounds and their modulatory effects on autophagy, as fine-tuning of autophagy could be translated into therapeutic applications for several cancers.

An Endogenous H2S-Activated Nanoplatform for Triple Synergistic Therapy of Colorectal Cancer

Overproduced hydrogen sulfide (H₂S) is a highly potential target for precise colorectal cancer (CRC) therapy; herein, a novel 5-Fu/Cur-P@HMPB nanomedicine is developed by coencapsulation of the natural anticancer drug curcumin (Cur) and the clinical chemotherapeutic drug 5-fluorouracil (5-Fu) into hollow mesoporous Prussian blue (HMPB). HMPB with low Fenton-catalytic activity can react with endogenous H₂S and convert into high Fenton-catalytic Prussian white (PW), which can generate in situ a high level of ^•OH to activate chemodynamic therapy (CDT) and meanwhile trigger autophagy. Importantly, the autophagy can be amplified by Cur to induce autophagic cell death; moreover, Cur also acted as a specific chemosensitizer of the chemotherapy drug 5-Fu, achieving a good synergistic antitumor effect. Such a triple synergistic therapy based on a novel nanomedicine has been verified both in vitro and in vivo to have high efficacy in CRC treatment, showing promising potential in translational medicine.

A Comprehensive Review on the Benefits and Problems of Curcumin with Respect to Human Health

Curcumin is the most important active component in turmeric extracts. Curcumin, a natural monomer from plants has received a considerable attention as a dietary supplement, exhibiting evident activity in a wide range of human pathological conditions. In general, curcumin is beneficial to human health, demonstrating pharmacological activities of anti-inflammation and antioxidation, as well as antitumor and immune regulation activities. Curcumin also presents therapeutic potential in neurodegenerative, cardiovascular and cerebrovascular diseases. In this review article, we summarize the advancements made in recent years with respect to curcumin as a biologically active agent in malignant tumors, Alzheimer’s disease (AD), hematological diseases and viral infectious diseases. We also focus on problems associated with curcumin from basic research to clinical translation, such as its low solubility, leading to poor bioavailability, as well as the controversy surrounding the association between curcumin purity and effect. Through a review and summary of the clinical research on curcumin and case reports of adverse effects, we found that the clinical transformation of curcumin is not successful, and excessive intake of curcumin may have adverse effects on the kidneys, heart, liver, blood and immune system, which leads us to warn that curcumin has a long way to go from basic research to application transformation.

Autophagy Protects against Eosinophil Cytolysis and Release of DNA

The presence of eosinophils in the airway is associated with asthma severity and risk of exacerbations. Eosinophils deposit their damaging products in airway tissue, likely by degranulation and cytolysis. We previously showed that priming blood eosinophils with IL3 strongly increased their cytolysis on aggregated IgG. Conversely, IL5 priming did not result in significant eosinophil cytolysis in the same condition. Therefore, to identify critical events protecting eosinophils from cell cytolysis, we examined the differential intracellular events between IL5- and IL3-primed eosinophils interacting with IgG. We showed that both IL3 and IL5 priming increased the eosinophil adhesion to IgG, phosphorylation of p38, and production of reactive oxygen species (ROS), and decreased the phosphorylation of cofilin. However, autophagic flux as measured by the quantification of SQSTM1-p62 and lipidated-MAP1L3CB over time on IgG, with or without bafilomycin-A1, was higher in IL5-primed compared to IL3-primed eosinophils. In addition, treatment with bafilomycin-A1, an inhibitor of granule acidification and autophagolysosome formation, enhanced eosinophil cytolysis and DNA trap formation in IL5-primed eosinophils. Therefore, this study suggests that increased autophagy in eosinophils protects from cytolysis and the release of DNA, and thus limits the discharge of damaging intracellular eosinophilic contents.

Nitric Oxide-Releasing NO–Curcumin Hybrid Inhibits Colon Cancer Cell Proliferation and Induces Cell Death In Vitro

Cancer is a leading cause of death worldwide, and most of the currently available drugs for cancer treatment have limited potential. Natural products and their relatives continue to represent a very high percentage of the drugs used for cancer treatment. Curcumin is one of several natural drugs that has recently attracted much attention due to its putative cancer-preventive and anticancer properties. As well, Nitric Oxide (NO) holds a great potential for NO-based treatments for a wide variety of diseases. Here, for the first time, we tested the anti-cancer activities of an NO–Curcumin hybrid, hypothesizing that by joining the effects of curcumin and NO in one compound, the hybrid compound would be more potent than curcumin alone in treating colon cancer. To compare the anti-cancer activities of curcumin and NO–curcumin, we treated different colon cancer cell lines with either curcumin or NO–curcumin and tested their effects on cell proliferation and death. Our results show that NO–curcumin is more effective in reducing cell proliferation and increasing cell death when compared to curcumin. In addition, NO–curcumin has a lower IC50 compared to curcumin. Altogether, our results demonstrate for the first time that an NO–curcumin hybrid has more potent anti-cancer activity compared to curcumin alone, making it a potential future treatment for cancer and perhaps other diseases.

Crosstalk Between ROS and Autophagy in Tumorigenesis: Understanding the Multifaceted Paradox

Cancer formation is a highly regulated and complex process, largely dependent on its microenvironment. This complexity highlights the need for developing novel target-based therapies depending on cancer phenotype and genotype. Autophagy, a catabolic process, removes damaged and defective cellular materials through lysosomes. It is activated in response to stress conditions such as nutrient deprivation, hypoxia, and oxidative stress. Oxidative stress is induced by excess reactive oxygen species (ROS) that are multifaceted molecules that drive several pathophysiological conditions, including cancer. Moreover, autophagy also plays a dual role, initially inhibiting tumor formation but promoting tumor progression during advanced stages. Mounting evidence has suggested an intricate crosstalk between autophagy and ROS where they can either suppress cancer formation or promote disease etiology. This review highlights the regulatory roles of autophagy and ROS from tumor induction to metastasis. We also discuss the therapeutic strategies that have been devised so far to combat cancer. Based on the review, we finally present some gap areas that could be targeted and may provide a basis for cancer suppression.

Transcriptomic Profiling Reveals AKR1C1 and AKR1C3 Mediate Cisplatin Resistance in Signet Ring Cell Gastric Carcinoma via Autophagic Cell Death

Signet ring cell gastric carcinoma (SRCGC) is a lethal malignancy that has developed drug resistance to cisplatin therapies. The aim of this study was to characterize the acquisition of the cisplatin-resistance SRCGC cell line (KATO/DDP cells) and to understand the molecular mechanisms underlying cisplatin resistance. Transcriptomic and bioinformatic analyses were used to identify the candidate gene. This was confirmed by qPCR and Western blot. Aldoketoreductase1C1 and 1C3 (AKR1C1 and AKR1C3) were the most promising molecules in KATO/DDP cells. A specific inhibitor of AKR1C1 (5PBSA) and AKR1C3 (ASP9521) was used to enhance cisplatin-induced KATO/DPP cell death. Although cisplatin alone induced KATO/DDP apoptosis, a combination treatment of cisplatin and the AKR1C inhibitors had no influence on percent cell apoptosis. In conjunction with the autophagy inhibitor, 3MA, attenuated the effects of 5PBSA or ASP9521 to enhance cisplatin-induced cell death. These results indicated that AKR1C1 and 1C3 regulated cisplatin-induced KATO/DDP cell death via autophagy. Moreover, cisplatin in combination with AKR1C inhibitors and N-acetyl cysteine increased KATO/DDP cells' viability when compared with a combination treatment of cisplatin and the inhibitors. Taken together, our results suggested that AKR1C1 and 1C3 play a crucial role in cisplatin resistance of SRCGC by regulating redox-dependent autophagy.

Microenvironmental Reactive Oxygen Species in Colorectal Cancer: Involved Processes and Therapeutic Opportunities

Colorectal cancer (CRC) is the fourth most common cause of cancer deaths worldwide. Although screening programs have reduced mortality rates, there is a need for research focused on finding the main factors that lead primary CRC to progress and metastasize. During tumor progression, malignant cells modify their habitat, corrupting or transforming cells of different origins and creating the tumor microenvironment (TME). Cells forming the TME like macrophages, neutrophils, and fibroblasts generate reactive oxygen species (ROS) that modify the cancer niche. The effects of ROS in cancer are very diverse: they promote cellular proliferation, epithelial-to-mesenchymal transition (EMT), evasion of cell death programs, migration, and angiogenesis. Due to the multifaceted role of ROS in cancer cell survival and function, ROS-modulating agents such as antioxidants or pro-oxidants could have therapeutic potential in cancer prevention and/or as a complement to systemic treatments. In this review, we will examine the main ROS producer cells and their effects on cancer progression and metastasis. Furthermore, we will enumerate the latest clinical trials where pro-oxidants and antioxidants have therapeutic uses in CRC.

Current Advances and Outlook in Gastric Cancer Chemoresistance: A Review

BACKGROUND

Surgical resection of the lesion is the standard primary treatment of gastric cancer. Unfortunately, most patients are already in the advanced stage of the disease when they are diagnosed with gastric cancer. Alternative therapies, such as radiation therapy and chemotherapy, can achieve only very limited benefits. The emergence of cancer drug resistance has always been the major obstacle to the cure of tumors. The main goal of modern cancer pharmacology is to determine the underlying mechanism of anticancer drugs.

OBJECTIVE

Here, we mainly review the latest research results related to the mechanism of chemotherapy resistance in gastric cancer, the application of natural products in overcoming the chemotherapy resistance of gastric cancer, and the new strategies currently being developed to treat tumors based on immunotherapy and gene therapy.

CONCLUSION

The emergence of cancer drug resistance is the main obstacle in achieving alleviation and final cure for gastric cancer. Mixed therapies are considered to be a possible way to overcome chemoresistance. Natural products are the main resource for discovering new drugs specific for treating chemoresistance, and further research is needed to clarify the mechanism of natural product activity in patients. .

Targeting Drug Chemo-Resistance in Cancer Using Natural Products

Cancer is one of the leading causes of death globally. The development of drug resistance is the main contributor to cancer-related mortality. Cancer cells exploit multiple mechanisms to reduce the therapeutic effects of anticancer drugs, thereby causing chemotherapy failure. Natural products are accessible, inexpensive, and less toxic sources of chemotherapeutic agents. Additionally, they have multiple mechanisms of action to inhibit various targets involved in the development of drug resistance. In this review, we have summarized the basic research and clinical applications of natural products as possible inhibitors for drug resistance in cancer. The molecular targets and the mechanisms of action of each natural product are also explained. Diverse drug resistance biomarkers were sensitive to natural products. P-glycoprotein and breast cancer resistance protein can be targeted by a large number of natural products. On the other hand, protein kinase C and topoisomerases were less sensitive to most of the studied natural products. The studies discussed in this review will provide a solid ground for scientists to explore the possible use of natural products in combination anticancer therapies to overcome drug resistance by targeting multiple drug resistance mechanisms.

Dietary polyphenols in chemoprevention and synergistic effect in cancer: Clinical evidences and molecular mechanisms of action

BACKGROUND

Epidemiological studies has revealed that a diet rich in fruits and vegetables could lower the risk of certain cancers. In this setting, natural polyphenols are potent anticancer bioactive compounds to overcome the non-target specificity, undesirable cytotoxicity and high cost of treatment cancer chemotherapy.

PURPOSE

The review focuses on diverse classifications of the chemical diversity of dietary polyphenol and their molecular targets, modes of action, as well as preclinical and clinical applications in cancer prevention.

RESULTS

The dietary polyphenols exhibit chemo-preventive activity through modulation of apoptosis, autophagy, cell cycle progression, inflammation, invasion and metastasis. Polyphenols possess strong antioxidant activity and control multiple molecular events through activation of tumor suppressor genes and inhibition of oncogenes involved in carcinogenesis. Numerous in vitro and in vivo studies have evidenced that these dietary phytochemicals regulate critical molecular targets and pathways to limit cancer initiation and progression. Moreover, natural polyphenols act synergistically with existing clinically approved drugs. The improved anticancer activity of combinations of polyphenols and anticancer drugs represents a promising perspective for clinical applications against many human cancers.

CONCLUSION

The anticancer properties exhibited by dietary polyphenols are mainly attributed to their anti-metastatic, anti-proliferative, anti-angiogenic, anti-inflammatory, cell cycle arrest, apoptotic and autophagic effects. Hence, regular consumption of dietary polyphenols as food or food additives or adjuvants can be a promising tactic to preclude adjournment or cancer therapy.

Targeting Autophagy with Natural Compounds in Cancer: A Renewed Perspective from Molecular Mechanisms to Targeted Therapy

Natural products are well-characterized to have pharmacological or biological activities that can be of therapeutic benefits for cancer therapy, which also provide an important source of inspiration for discovery of potential novel small-molecule drugs. In the past three decades, accumulating evidence has revealed that natural products can modulate a series of key autophagic signaling pathways and display therapeutic effects in different types of human cancers. In this review, we focus on summarizing some representative natural active compounds, mainly including curcumin, resveratrol, paclitaxel, Bufalin, and Ursolic acid that may ultimately trigger cancer cell death through the regulation of some key autophagic signaling pathways, such as RAS-RAF-MEK-ERK, PI3K-AKT-mTOR, AMPK, ULK1, Beclin-1, Atg5 and p53. Taken together, these inspiring findings would shed light on exploiting more natural compounds as candidate small-molecule drugs, by targeting the crucial pathways of autophagy for the future cancer therapy.

Photothermal photodynamic therapy and enhanced radiotherapy of targeting copolymer-coated liquid metal nanoparticles on liver cancer

The maximized therapeutic efficacy in tumor treatment can be achieved with combination therapy. Herein, a metronidazole (MN) and RGD peptides were linked with the copolymer chains of polyacrylic acid (PAA) and polyethylene glycol (PEG) by condensation and Michael addition reactions, respectively, named as RGD-PEG-PAA-MN. Subsequently, liquid-metal (LM) nanoparticles broken by ultrasonication were coated with modified copolymer, forming RGD-PEG-PAA-MN@LM nanoparticles. These nanoparticles with the degradation under an acidic condition could target to tumor cells, and LM of these composited nanoparticles could not only efficiently convert the photoenergy of near infrared (NIR) into thermal energy, but also produce more reactive oxygen species under NIR or X ray irradiation. Furthermore, MN in the composited nanoparticles could enhance their radiation sensitivity of tumor tissues with hypoxia condition. The synergic effect of these nanoparticles on cancer limitation after the sequential radiations of NIR and X ray was significantly higher than the single radiation. In the experiments of tumor bearing mice, the volume of the tumor in RGD-PEG-PAA-MN@LM group at 14th day after two radiations of NIR and X-ray were significantly smaller than LM group, and the tumor of RGD-PEG-PAA-MN@LM group at 14th day after two radiations almost disappeared, suggesting better synergistic effect of RGD-PEG-PAA-MN@LM nanoparticles on photothermal conversion, photodynamics under two irradiations and their enhanced sensitization of X-ray radiation. Our results indicated that the prepared nanoparticles would be applied in the combinational therapy of liver tumor by the photothermal, photodynamic and sensitized radiation.

Reactive Oxygen Species as a Link between Antioxidant Pathways and Autophagy

Reactive oxygen species (ROS) are highly reactive molecules that can oxidize proteins, lipids, and DNA. Under physiological conditions, ROS are mainly generated in the mitochondria during aerobic metabolism. Under pathological conditions, excessive ROS disrupt cellular homeostasis. High levels of ROS result in severe oxidative damage to the cellular machinery. However, a low/mild level of ROS could serve as a signal to trigger cell survival mechanisms. To prevent and cope with oxidative damage to biomolecules, cells have developed various antioxidant and detoxifying mechanisms. Meanwhile, ROS can initiate autophagy, a process of self-clearance, which helps to reduce oxidative damage by engulfing and degrading oxidized substance. This review summarizes the interactions among ROS, autophagy, and antioxidant pathways. The effects of natural phytochemicals on autophagy induction, antioxidation, and dual-function are also discussed.

Curcumin Suppresses TGF-β1-Induced Myofibroblast Differentiation and Attenuates Angiogenic Activity of Orbital Fibroblasts

Orbital fibrosis, a hallmark of tissue remodeling in Graves’ ophthalmopathy (GO), is a chronic, progressive orbitopathy with few effective treatments. Orbital fibroblasts are effector cells, and transforming growth factor β1 (TGF-β1) acts as a critical inducer to promote myofibroblast differentiation and subsequent tissue fibrosis. Curcumin is a natural compound with anti-fibrotic activity. This study aims to investigate the effects of curcumin on TGF-β1-induced myofibroblast differentiation and on the pro-angiogenic activities of orbital fibroblasts. Orbital fibroblasts from one healthy donor and three patients with GO were collected for primary cell culture and subjected to myofibroblast differentiation under the administration of 1 or 5 ng/mL TGF-β1 for 24 h. The effects of curcumin on TGF-β1-induced orbital fibroblasts were assessed by measuring the cellular viability and detecting the expression of myofibroblast differentiation markers, including connective tissue growth factor (CTGF) and α-smooth muscle actin (α-SMA). The pro-angiogenic potential of curcumin-treated orbital fibroblasts was evaluated by examining the transwell migration and tube-forming capacities of fibroblast-conditioned EA.hy926 and HMEC-1 endothelial cells. Treatment of orbital fibroblasts with curcumin inhibited the TGF-β1 signaling pathway and attenuated the expression of CTGF and α-SMA induced by TGF-β1. Curcumin, at the concentration of 5 μg/mL, suppressed 5 ng/mL TGF-β1-induced pro-angiogenic activities of orbital fibroblast-conditioned EA hy926 and HMEC-1 endothelial cells. Our findings suggest that curcumin reduces the TGF-β1-induced myofibroblast differentiation and pro-angiogenic activity in orbital fibroblasts. The results support the potential application of curcumin for the treatment of GO.

Chemical diversity of dietary phytochemicals and their mode of chemoprevention

Despite the advancement in prognosis, diagnosis and treatment, cancer has emerged as the second leading cause of disease-associated death across the globe. With the remarkable application of synthetic drugs in cancer therapy and the onset of therapy-associated adverse effects, dietary phytochemicals have been materialized as potent anti-cancer drugs owing to their antioxidant, apoptosis and autophagy modulating activities. With dynamic regulation of apoptosis and autophagy in association with cell cycle regulation, inhibition in cellular proliferation, invasion and migration, dietary phytochemicals have emerged as potent anti-cancer pharmacophores. Dietary phytochemicals or their synthetic analogous as individual drug candidates or in combination with FDA approved chemotherapeutic drugs have exhibited potent anti-cancer efficacy. With the advancement in cancer therapeutics, dietary phytochemicals hold high prevalence for their use as precision and personalized medicine to replace conventional chemotherapeutic drugs. Hence, keeping these perspectives in mind, this review focuses on the diversity of dietary phytochemicals and their molecular mechanism of action in several cancer subtypes and tumor entities. Understanding the possible molecular key players involved, the use of dietary phytochemicals will thrive a new horizon in cancer therapy.

Phytochemicals as a Complement to Cancer Chemotherapy: Pharmacological Modulation of the Autophagy-Apoptosis Pathway

Bioactive plant derived compounds are important for a wide range of therapeutic applications, and some display promising anticancer properties. Further evidence suggests that phytochemicals modulate autophagy and apoptosis, the two crucial cellular pathways involved in the underlying pathobiology of cancer development and regulation. Pharmacological targeting of autophagy and apoptosis signaling using phytochemicals therefore offers a promising strategy that is complementary to conventional cancer chemotherapy. In this review, we sought to highlight the molecular basis of the autophagic-apoptotic pathway to understand its implication in the pathobiology of cancer, and explore this fundamental cellular process as a druggable anticancer target. We also aimed to present recent advances and address the limitations faced in the therapeutic development of phytochemical-based anticancer drugs.

Oxidative Stress in Cancer Cell Metabolism

Reactive oxygen species (ROS) are important in regulating normal cellular processes whereas deregulated ROS leads to the development of a diseased state in humans including cancers. Several studies have been found to be marked with increased ROS production which activates pro-tumorigenic signaling, enhances cell survival and proliferation and drives DNA damage and genetic instability. However, higher ROS levels have been found to promote anti-tumorigenic signaling by initiating oxidative stress-induced tumor cell death. Tumor cells develop a mechanism where they adjust to the high ROS by expressing elevated levels of antioxidant proteins to detoxify them while maintaining pro-tumorigenic signaling and resistance to apoptosis. Therefore, ROS manipulation can be a potential target for cancer therapies as cancer cells present an altered redox balance in comparison to their normal counterparts. In this review, we aim to provide an overview of the generation and sources of ROS within tumor cells, ROS-associated signaling pathways, their regulation by antioxidant defense systems, as well as the effect of elevated ROS production in tumor progression. It will provide an insight into how pro- and anti-tumorigenic ROS signaling pathways could be manipulated during the treatment of cancer.

Curcumin activates Nrf2 through PKCδ-mediated p62 phosphorylation at Ser351

Curcumin, a phytochemical extracted from Curcuma longa rhizomes, is known to be protective in neurons via activation of Nrf2, a master regulator of endogenous defense against oxidative stress in cells. However, the exact mechanism by which curcumin activates Nrf2 remains controversial. Here, we observed that curcumin induced the expression of genes downstream of Nrf2 such as HO-1, NQO1, and GST-mu1 in neuronal cells, and increased the level of Nrf2 protein. Notably, the level of p62 phosphorylation at S351 (S349 in human) was significantly increased in cells treated with curcumin. Additionally, curcumin-induced Nrf2 activation was abrogated in p62 knockout (−/−) MEFs, indicating that p62 phosphorylation at S351 played a crucial role in curcumin-induced Nrf2 activation. Among the kinases involved in p62 phosphorylation at S351, PKCδ was activated in curcumin-treated cells. The phosphorylation of p62 at S351 was enhanced by transfection of PKCδ expression plasmid; in contrast, it was inhibited in cells treated with PKCδ-specific siRNA. Together, these results suggest that PKCδ is mainly involved in curcumin-induced p62 phosphorylation and Nrf2 activation. Accordingly, we demonstrate for the first time that curcumin activates Nrf2 through PKCδ-mediated p62 phosphorylation at S351.

Mucin corona delays intracellular trafficking and alleviates cytotoxicity of nanoplastic-benzopyrene combined contaminant

Nanoplastics have recently become a worldwide concern as newly emerging airborne pollutants, which can associate with polycyclic aromatic hydrocarbons (PAHs) and form combined contaminant nanoparticles (CCNPs). After being inhaled in the respiratory system, the CCNPs would first encounter the mucous gel layer being rich in mucin. Herein, polystyrene-benzopyrene (PS@Bap) NPs were prepared as CCNPs model and their interaction with mucin and the resultant biological responses were studied. It was observed that mucin corona stably attached to the CCNPs surface, which significantly altered the fate of the CCNPs in lung epithelial cells (A 549 cell line). The mucin corona would 1) stably adsorbed on PS@Bap at the early stages of endocytosis until degraded during the lysosomal transport and maturation process, 2) delay intracellular trafficking of PS@Bap and the progress of Bap detached from PS, 3) enhance uptake of PS@Bap but reduce the cytotoxicity elicited by PS@Bap, as indicated by cell viability, generation of reactive oxygen species, impairment on mitochondrial function, and further cell apoptosis. In addition, in vivo study also verified the enhanced effect of PS on the development of an acute lung inflammatory response induced by Bap. This study highlights the significance of incorporating the effects of mucin for precisely assessing the respiratory system toxicity of nanoplastics based CCNPs in atmospheric environments.

Modulation of Autophagy in Cancer Cells by Dietary Polyphenols

The role of autophagy is to degrade damaged or unnecessary cellular structures. Both in vivo and in vitro studies suggest a dual role of autophagy in cancer-it may promote the development of neoplasms, but it may also play a tumor protective function. The mechanism of autophagy depends on the genetic context, tumor stage and type, tumor microenvironment, or clinical therapy used. Autophagy also plays an important role in cell death as well as in the induction of chemoresistance of cancer cells. The following review describes the extensive autophagic cell death in relation to dietary polyphenols and cancer disease. The review documents increasing use of polyphenolic compounds in cancer prevention, or as agents supporting oncological treatment. Polyphenols are organic chemicals that exhibit antioxidant, anti-inflammatory, anti-angiogenic, and immunomodulating properties, and can also initiate the process of apoptosis. In addition, polyphenols reduce oxidative stress and protect against reactive oxygen species. This review presents in vitro and in vivo studies in animal models with the use of polyphenolic compounds such as epigallocatechin-3-gallate (EGCG), oleuropein, punicalgin, apigenin, resveratrol, pterostilbene, or curcumin and their importance in the modulation of autophagy-induced death of cancer cells.

Free Radicals as a Double-Edged Sword: The Cancer Preventive and Therapeutic Roles of Curcumin

Free radicals, generally composed of reactive oxygen species (ROS) and reactive nitrogen species (RNS), are generated in the body by various endogenous and exogenous systems. The overproduction of free radicals is known to cause several chronic diseases including cancer. However, increased production of free radicals by chemotherapeutic drugs is also associated with apoptosis in cancer cells, indicating the dual nature of free radicals. Among various natural compounds, curcumin manifests as an antioxidant in normal cells that helps in the prevention of carcinogenesis. It also acts as a prooxidant in cancer cells and is associated with inducing apoptosis. Curcumin quenches free radicals, induces antioxidant enzymes (catalase, superoxide dismutase, glutathione peroxidase), and upregulates antioxidative protein markers-Nrf2 and HO-1 that lead to the suppression of cellular oxidative stress. In cancer cells, curcumin aggressively increases ROS that results in DNA damage and subsequently cancer cell death. It also sensitizes drug-resistant cancer cells and increases the anticancer effects of chemotherapeutic drugs. Thus, curcumin shows beneficial effects in prevention, treatment and chemosensitization of cancer cells. In this review, we will discuss the dual role of free radicals as well as the chemopreventive and chemotherapeutic effects of curcumin and its analogues against cancer.

Chemotherapeutic efficacy of curcumin and resveratrol against cancer: Chemoprevention, chemoprotection, drug synergism and clinical pharmacokinetics

The frequent inefficiency of conventional cancer therapies due to drug resistance, non-targeted drug delivery, chemotherapy-associated toxic side effects turned the focus to bioactive phytochemicals. In this context, curcumin and resveratrol have emerged as potent chemopreventive and chemoprotective compounds modulating apoptotic and autophagic cell death pathways in cancer in vitro and in vivo. As synergistic agents in combination with clinically established anticancer drugs, the enhanced anticancer activity at reduced chemotherapy-associated toxicity towards normal organs can be explained by improved pharmacokinetics, pharmacodynamics, bioavailability and metabolism. With promising preclinical and clinical applications, the design of drug-loaded nanoparticles, nanocarriers, liposomes and micelles have gained much attention to improve target specificity and drug efficacy. The present review focuses on the molecular modes of chemoprevention, chemoprotection and drug synergism with special emphasis to preclinical and clinical applications, pharmacokinetics, pharmacodynamics and advanced drug delivery methods for the development of next-generation personalized cancer therapeutics.

Role of Autophagy in Cancer Cell Response to Nucleolar and Endoplasmic Reticulum Stress

Eukaryotic cells are exposed to many internal and external stimuli that affect their fate. In particular, the exposure to some of these stimuli induces stress triggering a variety of stress responses aimed to re-establish cellular homeostasis. It is now established that the deregulation of stress response pathways plays a central role in cancer initiation and progression, allowing the adaptation of cells to an altered state in the new environment. Autophagy is a tightly regulated pathway which exerts “housekeeping” role in physiological processes. Recently, a growing amount of evidence highlighted the crucial role of autophagy in the regulation of integrated stress responses, including nucleolar and endoplasmic reticulum. In this review, we attempt to afford an overview of the complex role of nucleolar and endoplasmic reticulum stress-response mechanisms in the regulation of autophagy in cancer and cancer treatment.

Dietary Mitophagy Enhancer: A Strategy for Healthy Brain Aging?

Recently, nutritional interventions have received attention as promising approaches to promote human health during a lifespan. The Mediterranean and Okinawan diets have been associated with longevity and decreasing risk for age-related diseases in contrast to the Western diet. The effect might be due to several antioxidative bioactive compounds highly consumed in both diets, namely, resveratrol, hydroxytyrosol, oleuropein, curcumin, and spermidine. This review aims to address the underlying mechanisms of these compounds to enhance mental fitness throughout life with a focus on brain mitophagy. Mitophagy is the autophagic clearance of dysfunctional, redundant, and aged mitochondria. In aging and neurodegenerative disorders, mitophagy is crucial to preserve the autophagy mechanism of the whole cell, especially during oxidative stress. Growing evidence indicates that curcumin, astaxanthin, resveratrol, hydroxytyrosol, oleuropein, and spermidine might exert protective functions via antioxidative properties and as well the enhanced induction of mitophagy mediators. The compounds seem to upregulate mitophagy and thereby alleviate the clearance of dysfunctional and aged mitochondria as well as mitogenesis. Thus, the Mediterranean or Okinawan diet could represent a feasible nutritional approach to reduce the risk of developing age-related cognitive impairment and corresponding disorders via the stimulation of mitophagy and thereby ensure a balanced redox state of brain cells.

Curcumin induces G2/M arrest and triggers autophagy, ROS generation and cell senescence in cervical cancer cells

Our study explored the tumor-suppressive effect of curcumin on cervical cancer cells. Cervical cancer is one of the most common cancers among women worldwide. Acquired resistance to chemotherapeutics and toxicity of such drugs has undermined the effectiveness of cervical cancer treatments. Therefore, the identification of novel chemotherapeutics is key to improving the survival of patients with cervical cancer. Curcumin has been shown to have various bioactivities, including antioxidant and antitumor effects; however, its effect on cervical cancer remains elusive. Here, we used the SiHa human cervical cancer cell line to test various concentrations of curcumin on the proliferation and apoptosis of cervical cancer cells. The involvement of autophagy and reactive oxygen species (ROS) in these effects were also tested by using specific autophagy inhibitors and ROS scavengers. Our results showed that curcumin induced ROS accumulation, apoptosis, autophagy, cell cycle arrest, and cellular senescence accompanied by upregulation of p53 and p21 proteins in SiHa cells.

Sanguisorba officinalis L. derived from herbal medicine prevents intestinal inflammation by inducing autophagy in macrophages

Disturbed activation of autophagy is implicated in the pathogenesis of inflammatory bowel disease. Accordingly, several autophagy-related genes have been identified as Crohn's disease susceptibility genes. We screened the autophagy activators from a library including 3,922 natural extracts using a high-throughput assay system. The extracts identified as autophagy activators were administered to mice with 2% dextran sodium sulfate (DSS). Among the autophagy inducers, Sanguisorba officinalis L. (SO) suppressed DSS-induced colitis. To identify the mechanism by which SO ameliorates colitis, epithelial cell and innate myeloid cells-specific Atg7-deficient mice (Villin-cre; Atg7^f/f and LysM-cre; Atg7^f/f mice, respectively) were analyzed. SO-mediated inhibition of colitis was observed in Villin-cre; Atg7^f/f mice. However, SO and a mixture of its components including catechin acid, ellagic acid, gallic acid, and ziyuglycoside II (Mix₄) did not suppressed colitis in LysM-cre; Atg7^f/f mice. In large intestinal macrophages (Mφ) of Atg7^f/f mice, SO and Mix₄ upregulated the expression of marker genes of anti-inflammatory Mφ including Arg1, Cd206, and Relma. However, these alterations were not induced in LysM-cre; Atg7^f/f mice. These findings indicate that SO and its active components ameliorate DSS-induced colitis by providing intestinal Mφ with anti-inflammatory profiles via promotion of Atg7-dependent autophagy.

Natural compounds modulate the crosstalk between apoptosis- and autophagy-regulated signaling pathways: Controlling the uncontrolled expansion of tumor cells

Due to the high number of annual cancer-related deaths, and the economic burden that this malignancy affects today's society, the study of compounds isolated from natural sources should be encouraged. Most cancers are the result of a combined effect of lifestyle, environmental factors, and genetic and hereditary components. Recent literature reveals an increase in the interest for the study of phytochemicals from traditional medicine, this being a valuable resource for modern medicine to identify novel bioactive agents with potential medicinal applications. Phytochemicals are components of traditional medicine that are showing promising application in modern medicine due to their antitumor activities. Recent studies regarding two major mechanisms underlying cancer development and regulation, apoptosis and autophagy, have shown that the signaling pathways of both these processes are significantly interconnected through various mechanisms of crosstalk. Phytochemicals are able to activate pro-autophagic and pro-apoptosis mechanisms. Understanding the molecular mechanism involved in apoptosis-autophagy relationship modulated by phytochemicals plays a key role in development of a new therapeutic strategy for cancer treatment. The purpose of this review is to outline the bioactive properties of the natural phytochemicals with validated antitumor activity, focusing particularly on their role in the regulation of apoptosis and autophagy crosstalk that triggers the uncontrolled expansion of tumor cells. Furthermore, we have also critically discussed the limitations and challenges of existing research strategies and the prospective research directions in this field.

Targeting Autophagic Pathways by Plant Natural Compounds in Cancer Treatment

Nowadays, natural compounds of plant origin with anticancer effects have gained more attention because of their clinical safety and broad efficacy profiles. Autophagy is a multistep lysosomal degradation pathway that may have a unique potential for clinical benefit in the setting of cancer treatment. To retrieve articles related to the study, the databases of Google Scholar, Web of sciences, Medline and Scopus, using the following keywords: Autophagic pathways; herbal medicine, oncogenic autophagic pathways, tumor-suppressive autophagic pathways, and cancer were searched. Although natural plant compounds such as resveratrol, curcumin, oridonin, gossypol, and paclitaxel have proven anticancer potential via autophagic signaling pathways, there is still a great need to find new natural compounds and investigate the underlying mechanisms, to facilitate their clinical use as potential anticancer agents through autophagic induction.

Hexavalent chromium-induced autophagic death of WRL-68 cells is mitigated by aqueous extract of Cuminum cyminum L. seeds

In this study, we assessed the potential of aqueous extract (CSE_aq) of Cuminum cyminum L. (cumin) seeds in protecting WRL-68 cells from hexavalent chromium [Cr(VI)]-induced oxidative injury. Cells exposed to Cr(VI) (10 μM CrO₃) for 24 h demonstrated a twofold increase in ROS, which, in turn, led to extensive oxidative stress, consequently causing colossal decline in cell viability (by 58.82 ± 9.79%) and proliferation (as was evident from a reduced expression of Ki-67, a proliferation marker). Immunofluorescence studies showed that Cr(VI) diminished the expressions of mTOR and survivin in WRL-68 cells. It also led to a substantial elevation of BECN1 expression, which suggested autophagy. Overall, our results indicated that 24 h exposure of WRL-68 cells to Cr(VI) caused oxidative stress-induced autophagic cell death. CSE_aq was found to protect WRL-68 cells from the same fate by refurbishing their viability and proliferation in a dose-dependent manner. The extract reduced ROS in these cells, which consequently decreased the degree of autophagic cell death by restoring expressions of mTOR, survivin and BECN1 to their respective normal levels. Biochemical assays revealed that CSE_aq is rich in phenolic constituents. Total phenolic content of CSE_aq demonstrated positive correlations with (i) its antioxidant potential, (ii) its alleviation of cellular oxidative stress and (iii) its cytoprotective efficacy in Cr(VI)-treated WRL-68 cells. We also identified the major phenolic constituents of CSE_aq. Our study suggested that polyphenols in CSE_aq might be responsible for protecting WRL-68 cells from Cr(VI)-governed oxidative assault that would have otherwise led to survivin/mTOR-mediated autophagic death.

Bioactive Phenolic Compounds in the Modulation of Central and Peripheral Nervous System Cancers: Facts and Misdeeds

Efficacious therapies are not available for the cure of both gliomas and glioneuronal tumors, which represent the most numerous and heterogeneous primary cancers of the central nervous system (CNS), and for neoplasms of the peripheral nervous system (PNS), which can be divided into benign tumors, mainly represented by schwannomas and neurofibromas, and malignant tumors of the peripheral nerve sheath (MPNST). Increased cellular oxidative stress and other metabolic aspects have been reported as potential etiologies in the nervous system tumors. Thus polyphenols have been tested as effective natural compounds likely useful for the prevention and therapy of this group of neoplasms, because of their antioxidant and anti-inflammatory activity. However, polyphenols show poor intestinal absorption due to individual intestinal microbiota content, poor bioavailability, and difficulty in passing the blood-brain barrier (BBB). Recently, polymeric nanoparticle-based polyphenol delivery improved their gastrointestinal absorption, their bioavailability, and entry into defined target organs. Herein, we summarize recent findings about the primary polyphenols employed for nervous system tumor prevention and treatment. We describe the limitations of their application in clinical practice and the new strategies aimed at enhancing their bioavailability and targeted delivery.

New insights into the interplay between autophagy, gut microbiota and inflammatory responses in IBD

One of the most significant challenges of inflammatory bowel disease (IBD) research is to understand how alterations in the symbiotic relationship between the genetic composition of the host and the intestinal microbiota, under impact of specific environmental factors, lead to chronic intestinal inflammation. Genome-wide association studies, followed by functional studies, have identified a role for numerous autophagy genes in IBD, especially in Crohn disease. Studies using in vitro and in vivo models, in addition to human clinical studies have revealed that autophagy is pivotal for intestinal homeostasis maintenance, gut ecology regulation, appropriate intestinal immune responses and anti-microbial protection. This review describes the latest researches on the mechanisms by which dysfunctional autophagy leads to disrupted intestinal epithelial function, gut dysbiosis, defect in anti-microbial peptide secretion by Paneth cells, endoplasmic reticulum stress response and aberrant immune responses to pathogenic bacteria. A better understanding of the role of autophagy in IBD pathogenesis may provide better sub-classification of IBD phenotypes and novel approaches for disease management.Abbreviations: AIEC: adherent-invasive Escherichia coli; AMPK: AMP-activated protein kinase; ATF6: activating transcription factor 6; ATG: autophagy related; Atg16l1[ΔIEC] mice: mice with Atg16l1 depletion specifically in intestinal epithelial cells; Atg16l1[HM] mice: mice hypomorphic for Atg16l1 expression; BCL2: B cell leukemia/lymphoma 2; BECN1: beclin 1, autophagy related; CALCOCO2: calcium binding and coiled-coil domain 2; CASP: caspase; CD: Crohn disease; CGAS: cyclic GMP-AMP synthase; CHUK/IKKA: conserved helix-loop-helix ubiquitous kinase; CLDN2: claudin 2; DAPK1: death associated protein kinase 1; DCs: dendritic cells; DSS: dextran sulfate sodium; EIF2A: eukaryotic translation initiation factor 2A; EIF2AK: eukaryotic translation initiation factor 2 alpha kinase; ER: endoplasmic reticulum; ERBIN: Erbb2 interacting protein; ERN1/IRE1A: ER to nucleus signaling 1; FNBP1L: formin binding protein 1-like; FOXP3: forkhead box P3; GPR65: G-protein coupled receptor 65; GSK3B: glycogen synthase kinase 3 beta; IBD: inflammatory bowel disease; IECs: intestinal epithelial cells; IFN: interferon; IL: interleukin; IL10R: interleukin 10 receptor; IRGM: immunity related GTPase M; ISC: intestinal stem cell; LAMP1: lysosomal-associated membrane protein 1; LAP: LC3-associated phagocytosis; MAP1LC3B: microtubule-associated protein 1 light chain 3 beta; LPS: lipopolysaccharide; LRRK2: leucine-rich repeat kinase 2; MAPK: mitogen-activated protein kinase; MHC: major histocompatibility complex; MIF: macrophage migration inhibitory factor; MIR/miRNA: microRNA; MTMR3: myotubularin related protein 3; MTOR: mechanistic target of rapamycin kinase; MYD88: myeloid differentiation primary response gene 88; NLRP3: NLR family, pyrin domain containing 3; NOD2: nucleotide-binding oligomerization domain containing 2; NPC: Niemann-Pick disease type C; NPC1: NPC intracellular cholesterol transporter 1; OMVs: outer membrane vesicles; OPTN: optineurin; PI3K: phosphoinositide 3-kinase; PRR: pattern-recognition receptor; PTPN2: protein tyrosine phosphatase, non-receptor type 2; PTPN22: protein tyrosine phosphatase, non-receptor type 22 (lymphoid); PYCARD/ASC: PYD and CARD domain containing; RAB2A: RAB2A, member RAS oncogene family; RELA: v-rel reticuloendotheliosis viral oncogene homolog A (avian); RIPK2: receptor (TNFRSF)-interacting serine-threonine kinase 2; ROS: reactive oxygen species; SNPs: single nucleotide polymorphisms; SQSTM1: sequestosome 1; TAX1BP1: Tax1 binding protein 1; Th: T helper 1; TIRAP/TRIF: toll-interleukin 1 receptor (TIR) domain-containing adaptor protein; TLR: toll-like receptor; TMEM173/STING: transmembrane protein 173; TMEM59: transmembrane protein 59; TNF/TNFA: tumor necrosis factor; Treg: regulatory T; TREM1: triggering receptor expressed on myeloid cells 1; UC: ulcerative colitis; ULK1: unc-51 like autophagy activating kinase 1; WT: wild-type; XBP1: X-box binding protein 1; XIAP: X-linked inhibitor of apoptosis.

Anti-Cancer and Ototoxicity Characteristics of the Curcuminoids, CLEFMA and EF24, in Combination with Cisplatin

In this study, we investigated whether the curcuminoids, CLEFMA and EF24, improved cisplatin efficacy and reduced cisplatin ototoxicity. We used the lung cancer cell line, A549, to determine the effects of the curcuminoids and cisplatin on cell viability and several apoptotic signaling mechanisms. Cellular viability was measured using the MTT assay. A scratch assay was used to measure cell migration and fluorescent spectrophotometry to measure reactive oxygen species (ROS) production. Western blots and luminescence assays were used to measure the expression and activity of apoptosis-inducing factor (AIF), caspases-3/7, -8, -9, and -12, c-Jun N-terminal kinases (JNK), mitogen-activated protein kinase (MAPK), and proto-oncogene tyrosine-protein kinase (Src). A zebrafish model was used to evaluate auditory effects. Cisplatin, the curcuminoids, and their combinations had similar effects on cell viability (IC₅₀ values: 2-16 μM) and AIF, caspase-12, JNK, MAPK, and Src expression, while caspase-3/7, -8, and -9 activity was unchanged or decreased. Cisplatin increased ROS yield (1.2-fold), and curcuminoid and combination treatments reduced ROS (0.75-0.85-fold). Combination treatments reduced A549 migration (0.51-0.53-fold). Both curcuminoids reduced auditory threshold shifts induced by cisplatin. In summary, cisplatin and the curcuminoids might cause cell death through AIF and caspase-12. The curcuminoids may potentiate cisplatin's effect against A549 migration, but may counteract cisplatin's effect to increase ROS production. The curcuminoids might also prevent cisplatin ototoxicity.

Dual-Functional Supernanoparticles with Microwave Dynamic Therapy and Microwave Thermal Therapy

The cytotoxic reactive oxygen species (ROS) generated by photoactivated sensitizers have been well explored in tumor therapy for nearly half a century, which is known as photodynamic therapy (PDT). The poor light penetration depth severely hinders PDT as a primary or adjuvant therapy for clinical indication. Whereas microwaves (MWs) are advantageous for deep penetration depth, the MW energy is considerably lower than that required for the activation of any species to induce ROS generation. Herein we find that liquid metal (LM) supernanoparticles activated by MW irradiation can generate ROS, such as ·OH and ·O₂. On this basis, we design dual-functional supernanoparticles by loading LMs and an MW heating sensitizer ionic liquid (IL) into mesoporous ZrO₂ nanoparticles, which can be activated by MW as the sole energy source for dynamic and thermal therapy concomitantly. The microwave sensitizer opens the door to an entirely novel dynamic treatment for tumors.