Nobiletin as an inducer of programmed cell death in cancer: a review

Recent advances in the therapeutic potential of nobiletin against respiratory diseases

BACKGROUND

Nobiletin is a natural polymethoxylated flavonoid widely present in citrus fruit peels. It has been demonstrated to exert the effects of anti-tumor, anti-inflammation, anti-oxidative, anti-apoptotic and improve cardiovascular function. Increasing evidences suggest that nobiletin plays an important role in respiratory diseases (RDs) treatment.

OBJECTIVE

This review aimed to investigate the therapeutic potential of nobiletin against RDs, such as lung cancer, COPD, pulmonary fibrosis, asthma, pulmonary infection, acute lung injury, coronavirus disease 2019, and pulmonary arterial hypertension.

METHODS

We retrieved extensive literature of relevant literatures in English until June 26, 2023 from the database of PubMed, Web of Science, and Scopus databases. The keywords of "nobiletin and lung", "nobiletin and respiratory disease", "nobiletin and chronic respiratory diseases", "nobiletin and metabolites", "nobiletin and pharmacokinetics", "nobiletin and toxicity" were searched in pairs. A total of 298 literatures were retrieved from the above database. After excluding the duplicates and reviews, 53 were included in the current review.

RESULTS

We found that the therapeutic mechanisms are based on different signaling pathways. Firstly, nobiletin inhibited the proliferation and suppressed the invasion and migration of cancer cells by regulating the related pathway or key target, like Bcl-2, PD-L1, PARP, and Akt/GSK3β/β-catenin in lung cancer treatment. Secondly, nobiletin treats COPD and ALI by targeting classical signaling pathway mediating inflammation. Besides, the available findings show that nobiletin exerts the effect of PF treatment via regulating mTOR pathway.

CONCLUSIONS

With the wide range of pharmacological activities, high efficiency and low toxicity, nobiletin can be used as a potential agent for preventing and treating RDs. These findings will contribute to further research on the molecular mechanisms of nobiletin and facilitate in-depth studies on nobiletin at both preclinical and clinical levels for the treatment of RDs.

Health Benefits of the Alkaloids from Lobeira (Solanum lycocarpum St. Hill): A Comprehensive Review

Solanum is the largest genus within the Solanaceae family and has garnered considerable attention in chemical and biological investigations over the past 30 years. In this context, lobeira or "fruta-do-lobo" (Solanum lycocarpum St. Hill), a species predominantly found in the Brazilian Cerrado, stands out. Beyond the interesting nutritional composition of the fruits, various parts of the lobeira plant have been used in folk medicine as hypoglycemic, sedative, diuretic, antiepileptic, and antispasmodic agents. These health-beneficial effects have been correlated with various bioactive compounds found in the plant, particularly alkaloids. In this review, we summarize the alkaloid composition of the lobeira plant and its biological activities that have been reported in the scientific literature in the last decades. The compiled data showed that lobeira plants and fruits contain a wide range of alkaloids, with steroidal glycoalkaloid solamargine and solasonine being the major ones. These alkaloids, but not limited to them, contribute to different biological activities verified in alkaloid-rich extracts/fractions from the lobeira, including antioxidant, anti-inflammatory, anticancer, antigenotoxic, antidiabetic, antinociceptive, and antiparasitic effects. Despite the encouraging results, additional research, especially toxicological, pre-clinical, and clinical trials, is essential to validate these human health benefits and ensure consumers' safety and well-being.

A new insight into Cd exposure-induced hemocyte reduction in Lymantria dispar larvae: Involvement of the ROS-ATF6-ER stress-apoptosis pathway

Hemocytes are important targets for heavy metal-induced immunotoxicity in insects. This study aimed to investigate the mechanism by which cadmium (Cd) exposure affects the hemocyte count in Lymantria dispar larvae. The results showed that the number of larval hemocytes was significantly decreased under Cd exposure, accompanied by a significant increase in the apoptosis rate and the expression of Caspase-3. The endoplasmic reticulum (ER) of hemocytes in the Cd-treated group showed irregular swelling. Expression levels of ER stress indicator genes (CHOP, Bip1, Bip2, Bip3, and Bip4) were significantly higher in the Cd-treated group. Among the three pathways that potentially mediate ER stress, only the key genes in the ATF6 pathway (ATF6, S1P-1, S1P-2, and WFS1) exhibited differential responses to Cd exposure. Cd exposure significantly increased the levels of reactive oxygen species (ROS) and the expression of oxidative stress-related genes (CNCC, P38, and ATF2) in hemocytes. Studies using inhibitors confirmed that apoptosis mediated the decrease in hemocyte count, ER stress mediated apoptosis, ATF6 pathway mediated ER stress, and ROS or oxidative stress mediated ER stress through the activation of the ATF6 pathway. Taken together, the ROS-ATF6-ER stress-apoptosis pathway is responsible for the reduction in the hemocyte count of Cd-treated L. dispar larvae.

Exploiting the immune system in hepatic tumor targeting: Unleashing the potential of drugs, natural products, and nanoparticles

Hepatic tumors present a formidable challenge in cancer therapeutics, necessitating the exploration of novel treatment strategies. In recent years, targeting the immune system has attracted interest to augment existing therapeutic efficacy. The immune system in hepatic tumors includes numerous cells with diverse actions. CD8+ T lymphocytes, T helper 1 (Th1) CD4+ T lymphocytes, alternative M1 macrophages, and natural killer (NK) cells provide the antitumor immunity. However, Foxp3+ regulatory CD4+ T cells (Tregs), M2-like tumor-associated macrophages (TAMs), and myeloid-derived suppressor cells (MDSCs) are the key immune inhibitor cells. Tumor stroma can also affect these interactions. Targeting these cells and their secreted molecules is intriguing for eliminating malignant cells. The current review provides a synopsis of the immune system components involved in hepatic tumor expansion and highlights the molecular and cellular pathways that can be targeted for therapeutic intervention. It also overviews the diverse range of drugs, natural products, immunotherapy drugs, and nanoparticles that have been investigated to manipulate immune responses and bolster antitumor immunity. The review also addresses the potential advantages and challenges associated with these approaches.

Nobiletin alleviates atherosclerosis by inhibiting lipid uptake via the PPARG/CD36 pathway

BACKGROUND

Atherosclerosis (AS) is a persistent inflammatory condition triggered and exacerbated by several factors including lipid accumulation, endothelial dysfunction and macrophages infiltration. Nobiletin (NOB) has been reported to alleviate atherosclerosis; however, the underlying mechanism remains incompletely understood.

METHODS

This study involved comprehensive bioinformatic analysis, including multidatabase target prediction; GO and KEGG enrichment analyses for function and pathway exploration; DeepSite and AutoDock for drug binding site prediction; and CIBERSORT for immune cell involvement. In addition, target intervention was verified via cell scratch assays, oil red O staining, ELISA, flow cytometry, qRT‒PCR and Western blotting. In addition, by establishing a mouse model of AS, it was demonstrated that NOB attenuated lipid accumulation and the extent of atherosclerotic lesions.

RESULTS

(1) Altogether, 141 potentially targetable genes were identified through which NOB could intervene in atherosclerosis. (2) Lipid and atherosclerosis, fluid shear stress and atherosclerosis may be the dominant pathways and potential mechanisms. (3) ALB, AKT1, CASP3 and 7 other genes were identified as the top 10 target genes. (4) Six genes, including PPARG, MMP9, SRC and 3 other genes, were related to the M0 fraction. (5) CD36 and PPARG were upregulated in atherosclerosis samples compared to the normal control. (6) By inhibiting lipid uptake in RAW264.7 cells, NOB prevents the formation of foam cell. (7) In RAW264.7 cells, the inhibitory effect of oxidized low-density lipoprotein on foam cells formation and lipid accumulation was closely associated with the PPARG signaling pathway. (8) In vivo validation showed that NOB significantly attenuated intra-arterial lipid accumulation and macrophage infiltration and reduced CD36 expression.

CONCLUSIONS

Nobiletin alleviates atherosclerosis by inhibiting lipid uptake via the PPARG/CD36 pathway.

Protection against cancer therapy-induced cardiovascular injury by planed-derived polyphenols and nanomaterials

Cancer therapy-induced heart injury is a significant concern for cancer patients undergoing chemotherapy, radiotherapy, immunotherapy, and also targeted molecular therapy. The use of these treatments can lead to oxidative stress and cardiomyocyte damage in the heart, which can result in heart failure and other cardiac complications. Experimental studies have revealed that chemotherapy drugs such as doxorubicin and cyclophosphamide can cause severe side effects such as cardiac fibrosis, electrophysiological remodeling, chronic oxidative stress and inflammation, etc., which may increase risk of cardiac disorders and attacks for patients that underwent chemotherapy. Similar consequences may also be observed for patients that undergo radiotherapy for left breast or lung malignancies. Polyphenols, a group of natural compounds with antioxidant and anti-inflammatory properties, have shown the potential in protecting against cancer therapy-induced heart injury. These compounds have been found to reduce oxidative stress, necrosis and apoptosis in the heart, thereby preserving cardiac function. In recent years, nanoparticles loaded with polyphenols have also provided for the delivery of these compounds and increasing their efficacy in different organs. These nanoparticles can improve the bioavailability and efficacy of polyphenols while minimizing their toxicity. This review article summarizes the current understanding of the protective effects of polyphenols and nanoparticles loaded with polyphenols against cancer therapy-induced heart injury. The article discusses the mechanisms by which polyphenols protect the heart, including antioxidant and anti-inflammation abilities. The article also highlights the potential benefits of using nanoparticles for the delivery of polyphenols.

The novel small molecule BH3 mimetic nobiletin synergizes with vorinostat to induce apoptosis and autophagy in small cell lung cancer

Small cell lung cancer (SCLC) is a highly lethal subtype of lung cancer with few therapeutic options; therefore, the identification of new targets and drugs with potent combination therapy is desirable. We previously screened BH3 mimetics from a natural product library, and in this study, we validated nobiletin as a BH3 mimetic. Specifically, we observed its combination potential and mechanism with vorinostat in SCLC in vitro and in vivo. The results showed that combination treatment with nobiletin and vorinostat reduced the proliferation of SCLC H82 cells and increased the levels of apoptotic proteins such as cleaved caspase-9 and cleaved PARP. The combination treatment increased LC3-II expression and induced autophagic cell death. In addition, this treatment significantly inhibited H82 cell xenograft SCLC tumor growth in nude mice. The combination treatment with nobiletin and vorinostat efficiently increased autophagy by inhibiting the PI3K-AKT-mTOR pathway and promoting dissociation of the BCL-2 and Beclin 1 complex, increasing the level of isolated Beclin 1 to stimulate autophagy. Molecular docking and surface plasmon resonance analysis showed that nobiletin stably bound to the BCL-2, BCL-XL and MCL-1 proteins with high affinity in a concentration-dependent manner. These results suggest that nobiletin is a BH3-only protein mimetic. Furthermore, the combination of nobiletin with vorinostat increased histone H3K9 and H3K27 acetylation levels in SCLC mouse tumor tissue and enhanced the expression of the BH3-only proteins BIM and BID. We conclude that nobiletin is a novel natural BH3 mimetic that can cooperate with vorinostat to induce apoptosis and autophagy in SCLC.

Tumor microenvironment remodeling in oral cancer: Application of plant derived-natural products and nanomaterials

Oral cancers consist of squamous cell carcinoma (SCC) and other malignancies in the mouth with varying degrees of invasion and differentiation. For many years, different modalities such as surgery, radiation therapy, and classical chemotherapy drugs have been used to control the growth of oral tumors. Nowadays, studies have confirmed the remarkable effects of the tumor microenvironment (TME) on the development, invasion, and therapeutic resistance of tumors like oral cancers. Therefore, several studies have been conducted to modulate the TME in various types of tumors in favor of cancer suppression. Natural products are intriguing agents for targeting cancers and TME. Flavonoids, non-flavonoid herbal-derived molecules, and other natural products have shown promising effects on cancers and TME. These agents, such as curcumin, resveratrol, melatonin, quercetin and naringinin have demonstrated potency in suppressing oral cancers. In this paper, we will review and discuss about the potential efficacy of natural adjuvants on oral cancer cells. Furthermore, we will review the possible therapeutic effects of these agents on the TME and oral cancer cells. Moreover, the potential of nanoparticles-loaded natural products for targeting oral cancers and TME will be reviewed. The potentials, gaps, and future perspectives for targeting TME by nanoparticles-loaded natural products will also be discussed.

Nrf2-mediated therapeutic effects of dietary flavones in different diseases

Oxidative stress (OS) is a pathological status that occurs when the body's balance between oxidants and antioxidant defense systems is broken, which can promote the development of many diseases. Nrf2, a redox-sensitive transcription encoded by NFE2L2, is the master regulator of phase II antioxidant enzymes and cytoprotective genes. In this context, Nrf2/ARE signaling can be a compelling target against OS-induced diseases. Recently, natural Nrf2/ARE regulators like dietary flavones have shown therapeutic potential in various acute and chronic diseases such as diabetes, neurodegenerative diseases, ischemia-reperfusion injury, and cancer. In this review, we aim to summarize nrf2-mediated protective effects of flavones in different conditions. Firstly, we retrospected the mechanisms of how flavones regulate the Nrf2/ARE pathway and introduced the mediator role Nrf2 plays in inflammation and apoptosis. Then we review the evidence that flavones modulated Nrf2/ARE pathway to prevent diseases in experimental models. Based on these literature, we found that flavones could regulate Nrf2 expression by mechanisms below: 1) dissociating the binding between Nrf2 and Keap1 via PKC-mediated Nrf2 phosphorylation and P62-mediated Keap1 autophagic degradation; 2) regulating Nrf2 nuclear translocation by various kinases like AMPK, MAPKs, Fyn; 3) decreasing Nrf2 ubiquitination and degradation via activating sirt1 and PI3K/AKT-mediated GSK3 inhibition; and 4) epigenetic alternation of Nrf2 such as demethylation at the promoter region and histone acetylation. In conclusion, flavones targeting Nrf2 can be promising therapeutic agents for various OS-related disorders. However, there is a lack of investigations on human subjects, and new drug delivery systems to improve flavones' treatment efficiency still need to be developed.

Mechanisms of cancer cell death induction by triptolide

Drug resistance is a hot topic issue in cancer research and therapy. Although cancer therapy including radiotherapy and anti-cancer drugs can kill malignant cells within the tumor, cancer cells can develop a wide range of mechanisms to resist the toxic effects of anti-cancer agents. Cancer cells may provide some mechanisms to resist oxidative stress and escape from apoptosis and attack by the immune system. Furthermore, cancer cells may resist senescence, pyroptosis, ferroptosis, necroptosis, and autophagic cell death by modulating several critical genes. The development of these mechanisms leads to resistance to anti-cancer drugs and also radiotherapy. Resistance to therapy can increase mortality and reduce survival following cancer therapy. Thus, overcoming mechanisms of resistance to cell death in malignant cells can facilitate tumor elimination and increase the efficiency of anti-cancer therapy. Natural-derived molecules are intriguing agents that may be suggested to be used as an adjuvant in combination with other anticancer drugs or radiotherapy to sensitize cancer cells to therapy with at least side effects. This paper aims to review the potential of triptolide for inducing various types of cell death in cancer cells. We review the induction or resistance to different cell death mechanisms such as apoptosis, autophagic cell death, senescence, pyroptosis, ferroptosis, and necrosis following the administration of triptolide. We also review the safety and future perspectives for triptolide and its derivatives in experimental and human studies. The anticancer potential of triptolide and its derivatives may make them effective adjuvants for enhancing tumor suppression in combination with anticancer therapy.

Antioxidant Capacity and Protective Effects on H2O2-Induced Oxidative Damage in PC12 Cells of the Active Fraction of Brassica rapa L

Brassica rapa L. (BR), a traditional biennial herb belonging to the Brassica species of Brassicaceae, has been widely used for functions of anti-inflammatory, antitumor, antioxidation, antiaging, and regulation of immunity. In this study, antioxidant activity and protective effects on H2O2-induced oxidative damage in PC12 cells of the active fractions of BR were investigated in vitro. Among all active fractions, the ethyl acetate fraction of ethanol extract from BR (BREE-Ea) showed the strongest antioxidant activity. Additionally, it was noted that BREE-Ea and n-butyl alcohol fraction of ethanol extract from BR (BREE-Ba) both have protective effects in oxidatively damaged PC12 cells, while BREE-Ea displayed the best protective effect in all determined experimental doses. Furthermore, flow cytometry (DCFH-DA staining) analysis indicated that BREE-Ea could reduce the H2O2-induced apoptosis in PC12 cells by reducing the production of intracellular reactive oxygen species (ROS) and increasing enzymatic activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px). Moreover, BREE-Ea could decrease the malondialdehyde (MDA) content and reduce the release of extracellular lactic dehydrogenase (LDH) from H2O2-induced PC12 cells. All these results demonstrate that BREE-Ea has a good antioxidant capacity and protective effect on PC12 cells against apoptosis induced by H2O2 and that it can be used as a good edible antioxidant to improve the body's endogenous antioxidant defense.

The interactions of docetaxel with tumor microenvironment

There are several interactions within the tumor microenvironment (TME) that affect the response of cancer cells to therapy. There are also a large number of cells and secretions in TME that increase resistance to therapy. Following the release of immunosuppressive, pro-angiogenic, and metastatic molecules by certain cells such as tumor-associated macrophages (TAMs), cancer-associated fibroblasts (CAFs), and cancer cells, immune evasion, angiogenesis, and metastasis may be induced. However, natural killer (NK) cells and cytotoxic CD8 + T lymphocytes (CTLs) can responsively release anticancer molecules. In addition, anticancer drugs can modulate these cells and their interactions in favor of either cancer resistance or therapy. Docetaxel belongs to taxanes, a class of anti-tumor drugs, which acts through the polymerization of tubulin and the induction of cell cycle arrest. Also, it has been revealed that taxanes including docetaxel affect cancer cells and the other cells within TME through some other mechanisms such as modulation of immune system responses, angiogenesis, and metastasis. In this paper, we explain the basic mechanisms of docetaxel interactions with malignant cells. Besides, we review the diverse effects of docetaxel on TME and cancer cells in consequence. Lastly, the modulatory effects of docetaxel alone or in conjunction with other anticancer agents on anti-tumor immunity, cancer cell resistance, angiogenesis, and metastasis will be discussed.

Naringenin and Hesperidin as Promising Alternatives for Prevention and Co-Adjuvant Therapy for Breast Cancer

Citrus (genus Citrus L.) fruits are essential sources of bioactive compounds with antioxidant properties, such as flavonoids. These polyphenolic compounds are divided into subclasses, in which flavanones are the most prominent. Among them, naringenin and hesperidin are emerging compounds with anticancer potential, especially for breast cancer (BC). Several mechanisms have been proposed, including the modulation of epigenetics, estrogen signaling, induction of cell death via regulation of apoptotic signaling pathways, and inhibition of tumor invasion and metastasis. However, this information is sparse in the literature and needs to be brought together to provide an overview of how naringenin and hesperidin can serve as therapeutic tools for drug development and as a successful co-adjuvant strategy against BC. This review detailed such mechanisms in this context and highlighted how naringenin and hesperidin could interfere in BC carcinogenesis and be helpful as potential alternative therapeutic sources for breast cancer treatment.

Mechanisms of cancer cell killing by metformin: a review on different cell death pathways

Cancer resistance to anti-tumour agents has been one of the serious challenges in different types of cancer treatment. Usually, an increase in the cell death markers can predict a higher rate of survival among patients diagnosed with cancer. By increasing the regulation of survival genes, cancer cells can display a higher resistance to therapy through the suppression of anti-tumour immunity and inhibition of cell death signalling pathways. Administration of certain adjuvants may be useful in order to increase the therapeutic efficiency of anti-cancer therapy through the stimulation of different cell death pathways. Several studies have demonstrated that metformin, an antidiabetic drug with anti-cancer properties, amplifies cell death mechanisms, especially apoptosis in a broad-spectrum of cancer cells. Stimulation of the immune system by metformin has been shown to play a key role in the induction of cell death. It seems that the induction or suppression of different cell death mechanisms has a pivotal role in either sensitization or resistance of cancer cells to therapy. This review explains the cellular and molecular mechanisms of cell death following anticancer therapy. Then, we discuss the modulatory roles of metformin on different cancer cell death pathways including apoptosis, mitotic catastrophe, senescence, autophagy, ferroptosis and pyroptosis.

Ferroptosis, necroptosis, and pyroptosis in the occurrence and development of ovarian cancer

Ovarian cancer (OC) is one of the most common malignancies that causes death in women and is a heterogeneous disease with complex molecular and genetic changes. Because of the relatively high recurrence rate of OC, it is crucial to understand the associated mechanisms of drug resistance and to discover potential target for rational targeted therapy. Cell death is a genetically determined process. Active and orderly cell death is prevalent during the development of living organisms and plays a critical role in regulating life homeostasis. Ferroptosis, a novel type of cell death discovered in recent years, is distinct from apoptosis and necrosis and is mainly caused by the imbalance between the production and degradation of intracellular lipid reactive oxygen species triggered by increased iron content. Necroptosis is a regulated non-cysteine protease–dependent programmed cell necrosis, morphologically exhibiting the same features as necrosis and occurring via a unique mechanism of programmed cell death different from the apoptotic signaling pathway. Pyroptosis is a form of programmed cell death that is characterized by the formation of membrane pores and subsequent cell lysis as well as release of pro-inflammatory cell contents mediated by the abscisin family. Studies have shown that ferroptosis, necroptosis, and pyroptosis are involved in the development and progression of a variety of diseases, including tumors. In this review, we summarized the recent advances in ferroptosis, necroptosis, and pyroptosis in the occurrence, development, and therapeutic potential of OC.

Modulation of the immune system by melatonin; implications for cancer therapy

Immune system interactions within the tumour have a key role in the resistance or sensitization of cancer cells to anti-cancer agents. On the other hand, activation of the immune system in normal tissues following chemotherapy or radiotherapy is associated with acute and late effects such as inflammation and fibrosis. Some immune responses can reduce the efficiency of anti-cancer therapy and also promote normal tissue toxicity. Modulation of immune responses can boost the efficiency of anti-tumour therapy and alleviate normal tissue toxicity. Melatonin is a natural body agent that has shown promising results for modulating tumour response to therapy and also alleviating normal tissue toxicity. This review tries to focus on the immunomodulatory actions of melatonin in both tumour and normal tissues. We will explain how anti-cancer drugs may cause toxicity for normal tissues and how tumours can adapt themselves to ionizing radiation and anti-cancer drugs. Then, cellular and molecular mechanisms of immunoregulatory effects of melatonin alone or combined with other anti-cancer agents will be discussed.