Licarin A induces cell death by activation of autophagy and apoptosis in non-small cell lung cancer cells

The Emerging Role of Natural Products in Cancer Treatment

The exploration of natural products as potential agents for cancer treatment has garnered significant attention in recent years. In this comprehensive review, we delve into the diverse array of natural compounds, including alkaloids, carbohydrates, flavonoids, lignans, polyketides, saponins, tannins, and terpenoids, highlighting their emerging roles in cancer therapy. These compounds, derived from various botanical sources, exhibit a wide range of mechanisms of action, targeting critical pathways involved in cancer progression such as cell proliferation, apoptosis, angiogenesis, and metastasis. Through a meticulous examination of preclinical and clinical studies, we provide insights into the therapeutic potential of these natural products across different cancer types. Furthermore, we discuss the advantages and challenges associated with their use in cancer treatment, emphasizing the need for further research to optimize their efficacy, pharmacokinetics, and delivery methods. Overall, this review underscores the importance of natural products in advancing cancer therapeutics and paves the way for future investigations into their clinical applications.

Natural products targeting autophagy and apoptosis in NSCLC: a novel therapeutic strategy

Lung cancer is the leading cause of cancer-related mortality worldwide, with non-small cell lung cancer (NSCLC) being the predominant type. The roles of autophagy and apoptosis in NSCLC present a dual and intricate nature. Additionally, autophagy and apoptosis interconnect through diverse crosstalk molecules. Owing to their multitargeting nature, safety, and efficacy, natural products have emerged as principal sources for NSCLC therapeutic candidates. This review begins with an exploration of the mechanisms of autophagy and apoptosis, proceeds to examine the crosstalk molecules between these processes, and outlines their implications and interactions in NSCLC. Finally, the paper reviews natural products that have been intensively studied against NSCLC targeting autophagy and apoptosis, and summarizes in detail the four most retrieved representative drugs. This paper clarifies good therapeutic effects of natural products in NSCLC by targeting autophagy and apoptosis and aims to promote greater consideration by researchers of natural products as candidates for anti-NSCLC drug discovery.

Anti-allodynic and anti-hyperalgesic activity of (±)-licarin A in neuropathic rats via NO-cyclic-GMP-ATP-sensitive K+ channel pathway

The study aimed to examine the effect of intraperitoneal and intrathecal (±)-licarin A in neuropathic pain induced by L5 and L6 spinal nerve ligation (SNL) in male Wistar rats and the possible involvement of the NO-cGMP-ATP-sensitive K+ channel pathway. Neuropathic pain signs (allodynia and hyperalgesia) were evaluated on postoperative Day 14 using von Frey filaments. Single intraperitoneal (0.01, 0.1, 1, and 10 mg/kg) and intrathecal (0.01, 0.1, 1, and 10 µg/rat) administration of (±)-licarin A improved allodynia and hyperalgesia. The (±)-licarin A-induced anti-allodynic and anti-hyperalgesic activity was prevented by the intrathecal injection of  l-NAME (100 µg/rat; nonselective nitric oxide synthase inhibitor), ODQ (10 µg/rat; guanylate cyclase inhibitor), and glibenclamide (50 µg/rat; adenosine triphosphate (ATP)-sensitive K+ channel blocker). The data suggest that (±)-licarin A exerts its anti-allodynic and anti-hyperalgesic activity by activating the NO-cGMP-ATP-sensitive K+ channel pathway.

Natural epidithiodiketopiperazine alkaloids as potential anticancer agents: Recent mechanisms of action, structural modification, and synthetic strategies

Cancer has become a grave health crisis that threatens the lives of millions of people worldwide. Because of the drawbacks of the available anticancer drugs, the development of novel and efficient anticancer agents should be encouraged. Epidithiodiketopiperazine (ETP) alkaloids with a 2,5-diketopiperazine (DKP) ring equipped with transannular disulfide or polysulfide bridges or S-methyl moieties constitute a special subclass of fungal natural products. Owing to their privileged sulfur units and intriguing architectural structures, ETP alkaloids exhibit excellent anticancer activities by regulating multiple cancer proteins/signaling pathways, including HIF-1, NF-κB, NOTCH, Wnt, and PI3K/AKT/mTOR, or by inducing cell-cycle arrest, apoptosis, and autophagy. Furthermore, a series of ETP alkaloid derivatives obtained via structural modification showed more potent anticancer activity than natural ETP alkaloids. To solve supply difficulties from natural resources, the total synthetic routes for several ETP alkaloids have been designed. In this review, we summarized several ETP alkaloids with anticancer properties with particular emphasis on their underlying mechanisms of action, structural modifications, and synthetic strategies, which will offer guidance to design and innovate potential anticancer drugs.

Oxidation Products from the Neolignan Licarin A by Biomimetic Reactions and Assessment of in vivo Acute Toxicity

Licarin A, a dihydrobenzofuranic neolignan presents in several medicinal plants and seeds of nutmeg, exhibits strong activity against protozoans responsible for Chagas disease and leishmaniasis. From biomimetic reactions by metalloporphyrin and Jacobsen catalysts, seven products were determined: four isomeric products yielded by epoxidation from licarin A, besides a new product yielded by a vicinal diol, a benzylic aldehyde, and an unsaturated aldehyde in the structure of the licarin A. The incubation with rat and human liver microsomes partially reproduced the biomimetic reactions by the production of the same epoxidized product of m/z 343 [M + H]⁺. In vivo acute toxicity assays of licarin A suggested liver toxicity based on biomarker enzymatic changes. However, microscopic analysis of tissues sections did not show any tissue damage as indicative of toxicity after 14 days of exposure. New metabolic pathways of the licarin A were identified after in vitro biomimetic oxidation reaction and in vitro metabolism by rat or human liver microsomes.

Antitumor effects and potential mechanisms of aconitine based on preclinical studies: an updated systematic review and meta-analysis

Background: Herbs originating from the Aconitum L. (Ranunculaceae), such as Aconitum carmichaelii Debeaux. (Wutou), Aconitum pendulum Busch. (Tiebangchui), and Aconitum kusnezoffii Reichb. (Caowu), etc. are highly valued for their medicinal properties. The roots and tubers of these herbs are commonly used to treat an array of ailments, including joint pain and tumors. The alkaloids present in them are the primary active components, with aconitine being the most notable. Aconitine has gained attention for its exceptional anti-inflammatory and analgesic properties, as well as its potential as an anti-tumor and cardiotonic agent. However, the exact process through which aconitine hinders the growth of cancerous cells and triggers their programmed cell death remains unclear. Therefore, we have undertaken a comprehensive systematic review and meta-analysis of the current research on the potential antitumor properties of aconitine. Methods: We conducted a thorough search of relevant preclinical studies in databases including PubMed, Web of Science, VIP, WanFang Data, CNKI, Embase, Cochrane Library, and National Center for Biotechnology Information (NCBI). The search was conducted up until 15 September 2022, and the data were statistically analyzed using RevMan 5.4 software. The number of tumor cell value-added, tumor cell apoptosis rate, thymus index (TI), and Bcl-2 gene expression level were the main indicators to be analyzed. Results: After applying the final inclusion criteria, a total of thirty-seven studies, comprising both in vivo and in vitro research were analyzed. The results showed that treatment with aconitine led to a significant reduction in tumor cell proliferation, a noteworthy increase in the rate of apoptosis among tumor cells, a decrease in the thymus index, and a reduction in the expression level of Bcl-2. These results suggested that aconitine could inhibit the proliferation, invasion, and migration abilities of tumor cells by regulating Bcl-2 etc., thereby enhancing the anti-tumor effects. Conclusion: In summary, our present study demonstrated that aconitine effectively reduced tumor size and volume, indicating a strong anti-tumor effect. Additionally, aconitine could increase the expression levels of caspase-3, Bax and other targets. Mechanistically, it may regulate the expression levels of Bax and Bcl-2 through the NF-κB signaling pathway, ultimately inhibiting tumor cell proliferation through autophagy.

Synthesis and Biological Activities of Dehydrodiisoeugenol: A Review

Dehydrodiisoeugenol (DHIE) is a neolignan found in more than 17 plant species, including herbs, fruit, and root. DHIE was, for the first time, isolated from Myristica fragrans bark in 1973. Since then, many methodologies have been used for the obtention of DHIE, including classical chemistry synthesis using metal catalysts and biocatalytic synthesis; employing horseradish peroxidase; peroxidase from Cocos nucifera; laccase; culture cells of plants; and microorganisms. Increasing evidence has indicated that DHIE has a wide range of biological activities: anti-inflammatory, anti-oxidant, anti-cancerogenic, and anti-microbial properties. However, evidence in vivo and in human beings is still lacking to support the usefulness potential of DHIE as a therapeutic agent. This study's review was created by searching for relevant DHIE material on websites such as Google Scholar, PubMed, SciFinder, Scholar, Science Direct, and others. This reviews the current state of knowledge regarding the different synthetical routes and biological applications of DHIE.

The role of autophagy and apoptosis in early brain injury after subarachnoid hemorrhage: an updated review

Subarachnoid hemorrhage (SAH) is a worldwide devastating type of stroke with high mortality and morbidity. Accumulating evidence show early brain injury (EBI) as the leading cause of mortality after SAH. The pathological processes involved in EBI include decreased cerebral blood flow, increased intracranial pressure, vasospasm, and disruption of the blood-brain barrier. In addition, neuroinflammation, oxidative stress, apoptosis, and autophagy have also been proposed to contribute to EBI. Among the various processes involved in EBI, neuronal apoptosis has been proven to be a key factor contributing to the poor prognosis of SAH patients. Meanwhile, as another important catabolic process maintaining the cellular and tissue homeostasis, autophagy has been shown to be neuroprotective after SAH. Studies have shown that enhancing autophagy reduced apoptosis, whereas inhibiting autophagy aggravate neuronal apoptosis after SAH. The physiological substrates and mechanisms of neuronal autophagy and apoptosis by which defects in neuronal function are largely unknown. In this review, we summarize and discuss the role of autophagy and apoptosis after SAH and contribute to further study for investigation of the means to control the balance between them.

Aconiti Lateralis Radix Praeparata as Potential Anticancer Herb: Bioactive Compounds and Molecular Mechanisms

Aconiti Lateralis Radix Praeparata (Fuzi in Chinese) is a traditional herbal medicine widely used in China and other Asian countries. In clinical practice, it is often used to treat heart failure, rheumatoid arthritis, and different kinds of pains. Fuzi extract and its active ingredients exert considerable anticancer, anti-inflammatory, and analgesic effects. The main chemical substances of Fuzi include alkaloids, polysaccharides, flavonoids, fatty acids, and sterols. Among of them, alkaloids and polysaccharides are responsible for the anticancer efficacy. Most bioactive alkaloids in Fuzi possess C19 diterpenoid mother nucleus and these natural products show great potential for cancer therapy. Moreover, polysaccharides exert extraordinary tumor-suppressive functions. This review comprehensively summarized the active ingredients, antineoplastic effects, and molecular mechanisms of Fuzi by searching PubMed, Web of Science, ScienceDirect, and CNKI. The anticancer effects are largely attributed to inducing apoptosis and autophagy, inhibiting proliferation, migration and invasion, regulating body immunity, affecting energy metabolism, as well as reversing multidrug resistance. Meanwhile, several signaling pathways and biological processes are mainly involved, such as NF-κB, EMT, HIF-1, p38 MAPK, PI3K/AKT/mTOR, and TCA cycle. Collectively, alkaloids and polysaccharides in Fuzi might serve as attractive therapeutic candidates for the development of anticancer drugs. This review would lay a foundation and provide a basis for further basic research and clinical application of Fuzi.

Circular RNA circCPA4 promotes tumorigenesis by regulating miR-214-3p/TGIF2 in lung cancer

Background

Lung cancer is the most prevalent malignancy in adults. Circular RNA (circRNA) circCPA4 (hsa_circ_0082374) is highly expressed in non‐small cell lung cancer (NSCLC). The purpose of this study was to explore the role and mechanism of circCPA4 in lung cancer.

Methods

CircCPA4, linear CPA4, TGF‐β‐induced factor homeobox 2 (TGIF2), and microRNA‐214‐3p (miR‐214‐3p) levels were measured by real‐time quantitative polymerase chain reaction (RT‐qPCR). The protein levels of TGIF2, Beclin1, and p62 were assessed by western blot assay. Colony numbers, migration, invasion, apoptosis, and cell cycle progression were examined by colony formation, wound‐healing, transwell, and flow cytometry assays, respectively. The binding relationship between miR‐214‐3p and circCPA4 or TGIF2 was predicted by StarBase or TargetScan and then verified by a dual‐luciferase reporter, RNA immunoprecipitation (RIP), and RNA pulldown assays. The biological role of circCPA4 on lung tumor growth was assessed by a xenograft tumor model in vivo, and TGIF2 and ki‐67 expression was assessed by immunohistochemistry.

Results

We determined that CircCPA4 and TGIF2 were increased, and miR‐214‐3p was decreased in lung cancer tissues and cells. Functionally, circCPA4 knockdown could suppress colony formation, migration, invasion, cell cycle progression, and expedite apoptosis of lung cancer cells in vitro. Mechanically, circCPA4 could regulate TGIF2 expression by sponging miR‐214‐3p. In addition, circCPA4 deficiency inhibited the tumor growth in lung cancer in the mouse model.

Conclusions

CircCPA4 could act as a sponge of miR‐214‐3p to upregulate TGIF2 expression, thereby promoting the progression of lung cancer cells. These findings suggested underlying therapeutic targets for the treatment of lung cancer.

Licarin A, a neolignan isolated from Nectandra oppositifolia Nees & Mart. (Lauraceae), exhibited moderate preclinical efficacy against Schistosoma mansoni infection

Schistosomiasis is a widespread human parasitic disease currently affecting over 200 million people, particularly in poor communities. Chemotherapy for schistosomiasis relies exclusively on praziquantel (PZQ). Previous studies have shown that licarin A (LIC-A), a dihydrobenzofuran neolignan, exhibited in vitro antiparasitic activity against Schistosoma mansoni adult worms. This study aimed to investigate the potential of LIC-A, isolated as main metabolite from leaves of Nectandra oppositifolia Nees & Mart. (Lauraceae), as an antischistosomal agent orally active in schistosomiasis animal model. PZQ was used as a reference compound. As result, LIC-A showed, at a single dose of 400 mg/kg, to be able to partially cure infected mice (worm burden reductions of ~50%). Parasite eggs, that are responsible for a variety of pathologies and transmission of schistosomiasis, were also moderately inhibited by LIC-A (egg burden reductions of ~50%-60%). Furthermore, it was observed that LIC-A achieved a slight reduction of hepatomegaly and splenomegaly. Collectively, although LIC-A was partially active when administered orally, these results give support for the antiparasitic potential LIC-A as lead compound for novel antischistosomal agent.

Bioactivity of fractions and constituents of Piper capense fruits towards a broad panel of cancer cells

ETHNOPHARMACOLOGICAL RELEVANCE

Piper capense is a medicinal spice whose fruits are traditionally used as aqueous decoction to heal several ailments such as trypanosomiasis, helminthic infections, and cancer.

AIM OF THE STUDY

(1) To perform phytochemical investigation of the methanol extract of Piper capense; (2) to evaluate the cytotoxicity of botanicals (PCF, fractions PCFa-e), isolated phytochemicals on a broad panel of animal and human cancer cell lines; (3) to evaluate the induction of apoptosis of the most active samples.

MATERIAL AND METHODS

Resazurin reduction assay (RRA) was used to determine the cytotoxicity of the studied samples. Cell cycle distribution (PI staining), apoptosis (annexin V/PI staining), mitochondrial membrane potential (MMP; JC-1) and reactive oxygen species (ROS; H₂DCFH-DA) were measured by flow cytometry. Column chromatography (CC) was used for the purification of PCF, whilst nuclear magnetic resonance (NMR) spectroscopic and mass spectrometric (MS) analyses were applied for structural elucidation.

RESULTS

The phytochemical investigation of PCF led to the isolation of 11 compounds: licarin B (1), licarin A (2), 7-(1,3-benzodioxol-5-yl)-7,8-dihydro-8-methyl-5-(2-propenyl)-furo[3,2-e]-1,3-benzodioxole (3), nitidine isocyanate (4), 5-hydroxy-7,4'-dimethoxyflavone (5), cardamomin (6), sitosterol (7) and stigmasterol (8), β-sitosterol 3-O-β-_D-glucopyranoside (9), oleanolic acid (10) and lupeol (11). Fraction PCFb, compound 2 and doxorubicin (as positive control drug) revealed cytotoxic effects towards the 18 tested cancer cell lines. The IC₅₀ values ranged from 6.1 μg/mL (against CCRF-CEM cells) to 44.2 μg/mL (against BRAF-V600E homozygous mutant melanoma cells) for PSCb; from 4.3 μM (against CCRF-CEM cells) to 21.8 μM (against HCT116 p53^-/-) for compound 2 and from 0.02 μM (against CCRF-CEM cells) to 123.0 μM (against CEM/ADR5000 cells) for doxorubicin. PCFb and compound 2 induced apoptosis in CCRF-CEM cells mediated by activation of caspase 3/7, 8 and 9, MMP alteration and increased ROS production.

CONCLUSION

Piper capense is a source of potent cytotoxic botanicals and phytochemicals that could help to fight various types of cancer including multidrug resistance phenotypes. PCFb and compound 2 should further be explored to develop new drugs to fight malignancies.

A novel Diels-Alder adduct of mulberry leaves exerts anticancer effect through autophagy-mediated cell death

Guangsangon E (GSE) is a novel Diels-Alder adduct isolated from leaves of Morus alba L, a traditional Chinese medicine widely applied in respiratory diseases. It is reported that GSE has cytotoxic effect on cancer cells. In our research, we investigated its anticancer effect on respiratory cancer and revealed that GSE induces autophagy and apoptosis in lung and nasopharyngeal cancer cells. We first observed that GSE inhibits cell proliferation and induces apoptosis in A549 and CNE1 cells. Meanwhile, the upregulation of autophagosome marker LC3 and increased formation of GFP-LC3 puncta demonstrates the induction of autophagy in GSE-treated cells. Moreover, GSE increases the autophagy flux by enhancing lysosomal activity and the fusion of autophagosomes and lysosomes. Next, we investigated that endoplasmic reticulum (ER) stress is involved in autophagy induction by GSE. GSE activates the ER stress through reactive oxygen species (ROS) accumulation, which can be blocked by ROS scavenger NAC. Finally, inhibition of autophagy attenuates GSE-caused cell death, termed as "autophagy-mediated cell death." Taken together, we revealed the molecular mechanism of GSE against respiratory cancer, which demonstrates great potential of GSE in the treatment of representative cancer.

Dehydrodiisoeugenol inhibits colorectal cancer growth by endoplasmic reticulum stress-induced autophagic pathways

Background

Dehydrodiisoeugenol (DEH), a novel lignan component extracted from nutmeg, which is the seed of Myristica fragrans Houtt, displays noticeable anti-inflammatory and anti-allergic effects in digestive system diseases. However, the mechanism of its anticancer activity in gastrointestinal cancer remains to be investigated.

Methods

In this study, the anticancer effect of DEH on human colorectal cancer and its underlying mechanism were evaluated. Assays including MTT, EdU, Plate clone formation, Soft agar, Flow cytometry, Electron microscopy, Immunofluorescence and Western blotting were used in vitro. The CDX and PDX tumor xenograft models were used in vivo.

Results

Our findings indicated that treatment with DEH arrested the cell cycle of colorectal cancer cells at the G1/S phase, leading to significant inhibition in cell growth. Moreover, DEH induced strong cellular autophagy, which could be inhibited through autophagic inhibitors, with a rction in the DEH-induced inhibition of cell growth in colorectal cancer cells. Further analysis indicated that DEH also induced endoplasmic reticulum (ER) stress and subsequently stimulated autophagy through the activation of PERK/eIF2α and IRE1α/XBP-1 s/CHOP pathways. Knockdown of PERK or IRE1α significantly decreased DEH-induced autophagy and retrieved cell viability in cells treated with DEH. Furthermore, DEH also exhibited significant anticancer activities in the CDX- and PDX-models.

Conclusions

Collectively, our studies strongly suggest that DEH might be a potential anticancer agent against colorectal cancer by activating ER stress-induced inhibition of autophagy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-01915-9.

Methyl gallate, gallic acid-derived compound, inhibit cell proliferation through increasing ROS production and apoptosis in hepatocellular carcinoma cells

Hepatocellular carcinoma (HCC) is a global health problem. Currently, there is no effective therapeutic strategy for HCC. Methyl gallate (MG), from plant-derived phenolic gallic acid, has exhibited antitumor efficacy. However, the effect of MG on HCC is unclear. In vitro growth activity was detected by a sulforhodamine assay. A zebrafish xenotransplantation was applied to evaluate the inhibitory effect of MG. Reactive oxygen species (ROS) production, autophagy, and lysosome formation were detected by specific dyes. Finally, apoptosis was examined using annexin V-FITC/PI staining and western blot was performed to determine the molecular mechanism. It was demonstrated that MG treatment inhibited the proliferation of Hep3B, Mahlavu, and HepJ5 cells. Xenotransplantation also showed that MG inhibited the growth of Hep3B and HepJ5 cells. MG treatment increased cellular levels of superoxide and oxidative stress. Increases in autophagy and lysosome formation were found after MG treatment. The western blot analysis showed that MG activated cleavage of caspase-3 and poly (SDP ribose) polymerase (PARP), modulated levels of the Bcl2, Bax, and Bad ligands, and induced apoptosis. MG induced autophagy with notable activation of beclin-1, autophagy related 5+12 (ATG5+12), and conversion of light chain 3-I (LC3-I) to II. Our study showed that MG exposure inhibited HCC proliferation both in vitro and in vivo. And blocking autophagy enhanced MG-induced cytotoxicity in HCC cells. These findings suggested MG might serve as a powerful therapeutic supplement for human HCC patients.

The Local Anesthetic Bupivacaine Inhibits the Progression of Non-Small Cell Lung Cancer by Inducing Autophagy Through Akt/mTOR Signaling

Non-small cell lung cancer (NSCLC) is a prevalent malignancy with high mortality and poor prognosis. Bupivacaine serves as a widely used local anesthetic and presents potential anti-tumor activity. Nevertheless, the function of bupivacaine in the NSCLC development remains elusive. Here, we tried to investigate the impact of bupivacaine on the NSCLC progression. Significantly, we revealed that bupivacaine was able to reduce the proliferation and induce the apoptosis of NSCLC cells. Bupivacaine could attenuate the invasion and migration in the cells. Mechanically, the treatment of bupivacaine increased the expression ratio of light chain 3B-II (LC3B-II)/LC3B-I and the expression of Beclin-1 in the NSCLC cells. Meanwhile, the expression of the autophagic adaptor protein p62 was decreased by bupivacaine treatment in the cells. The treatment of bupivacaine attenuated the phosphorylation of AKT and mTOR in the NSCLC cells. The AKT activator SC79 and autophagy inhibitor 3-methyladenine (3-MA) reversed the bupivacaine-inhibited phosphorylation of AKT and mTOR and bupivacaine-induced autophagy, as well as the bupivacaine-attenuated NSCLC progression in the cells. Bupivacaine could inhibit the tumor growth in vivo. In conclusion, we discovered that the local anesthetic bupivacaine inhibited the progression of NSCLC by inducing autophagy through Akt/mTOR signaling. Our finding provides new insights into the mechanism by which bupivacaine attenuates the development of NSCLC. Bupivacaine may serve as a potential anti-tumor candidate for the therapeutic strategy of NSCLC.

The PAD4 inhibitor GSK484 enhances the radiosensitivity of triple-negative breast cancer

Triple-negative breast cancer (TNBC) accounts for approximately 10-20% of all breast cancers and is one of the leading causes of mortality among females. Radiotherapy is essential during the treatment of breast cancer. Growing evidence has indicated that peptidyl arginine deiminase-4 (PAD4) inhibitor can alleviate the development of multiple cancers, including breast cancer, through inhibiting cell proliferation. GSK484 is considered to be a highly potent PAD4-selective inhibitors. However, the potential role and mechanism of GSK484 in TNBC remain unclear. In this study, we intended to explore the effects of GSK484 on the radiosensitivity of TNBC cell lines (MDA-MB-231 and BT-549). We found that the pretreatment of GSK484 enhanced irradiation (IR)-induced inhibitory effects on cell proliferation, migration and invasion. Besides, our findings revealed that GSK484 facilitated TNBC cell apoptosis. IR treatment-induced increase of the protein level of ATG5 and ATG7, and decrease of p62 protein level were countervailed by GSK484. In addition, GSK484 enhanced DNA damage induced by IR. Moreover, in vivo experiments demonstrated that the combined treatment of IR and GSK484 showed an obvious decline of tumor growth in contrast to IR-alone or GSK484-alone treatment. Overall, GSK484 may serve as a radiosensitizer of TNBC through inhibiting IR-induced autophagy.

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

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

Knockdown of TXNDC9 induces apoptosis and autophagy in glioma and mediates cell differentiation by p53 activation

Glioma is the most common malignant brain tumor. Because of its high degree of malignancy, the effect of surgical treatment, radiotherapy, chemotherapy, or immunotherapy is not ideal. TXNDC9 belongs to thioredoxin domain-containing proteins, which is involved in tumor progression. However, no research associated with TXNDC9 has been reported in glioma. In this study, we found that TXNDC9 was upregulated in glioma. Knockdown of TXNDC9 would prevent proliferation and metastasis, induce the apoptosis rate of glioma cells, and promote the expression Cleaved-caspase3, Cleaved-caspase8, Cleaved-caspase9. Meanwhile, knockdown of TXNDC9 induced autophagy by increasing the level of LC3 and Beclin-1. Cell morphology and expression analysis of GFAP, Vimentin, verified that TXNDC9 could regulate glioma cell differentiation. During this program, the expression of p53 changes dramatically. The apoptosis, autophagy, and cell differentiation program were blocked by p53 inhibitor treatment. In conclusion, the silencing of TXNDC9 induces apoptosis and autophagy in glioma and promotes cell differentiation by controlling p53 and may function as a new mechanism in glioma.

Boosting autophagy in sexual reproduction: a plant perspective

The key process of sexual reproduction is the successful fusion of the sperm and egg cell. Distinct from dynamic and flagellated animal sperm cells, higher flowering plant sperm cells are immotile. Therefore, plants have evolved a novel reproductive system to achieve fertilization and generate progenies. Plant sexual reproduction consists of multiple steps, mainly including gametophyte development, pollen-pistil recognition, pollen germination, double fertilization and postfertilization. During reproduction, active production, consumption and recycling of cellular components and energy are critically required to achieve fertilization. However, the underlying machinery of cellular degradation and turnover remains largely unexplored. Autophagy, the major catabolic pathway in eukaryotic cells, participates in regulating multiple aspects of plant activities, including abiotic and biotic stress resistance, pathogen response, senescence, nutrient remobilization and plant development. Nevertheless, a key unanswered question is how autophagy regulates plant fertilization and reproduction. Here, we focus on comparing and contrasting autophagy in several key reproductive processes of plant and animal systems to feature important distinctions and highlight future research directions of autophagy in angiosperm reproduction. We further discuss the potential crosstalk between autophagy and programmed cell death, which are often considered as two disconnected events in plant sexual reproduction.

TAF1L promotes development of oral squamous cell carcinoma via decreasing autophagy-dependent apoptosis

This study focused on investigating the relationships of TAF1L expression and clinical features or pathological stages of oral squamous cell carcinoma (OSCC), and its potential roles of TAF1L on OSCC development. Western blot and immunohistochemical staining were used to detect TAF1L expression in OSCC tissues and cells. Effects of TAF1L on OSCC cells in vitro were examined by cell proliferation assay, wound healing assay, transwell chamber assay, flow cytometry analysis and siRNA technique. Cellular key proteins related to cell autophagy and apoptosis were evaluated by Western blot and immunofluorescent staining. Moreover, functions of TAF1L on OSCC process were observed in nude mouse model. Testing results showed that expression of TAF1L protein was higher in OSCC tissues than that in normal oral epithelial or paracancerous tissues. Additionally, the level of TAF1L protein expression was upregulated in OSCC cell lines, compared to that in normal oral epithelial cells. Furthermore, cell proliferation, migration, autophagy and apoptosis were modulated post siRNA-TAF1L treatment in vitro. Especially, TAF1L knockdown-induced apoptotic activation on OSCC cells could be rescued by autophagic activator (Rapamycin). Moreover, that overexpression of TAF1L protein could promote the growth of OSCC cell xenografts was confirmed in nude mouse model. Taken together, it suggests that TAF1L may facilitate OSCC cells to escape cell apoptosis via autophagic activation for enhancing OSCC development.

Plumbagin engenders apoptosis in lung cancer cells via caspase-9 activation and targeting mitochondrial-mediated ROS induction

Plumbagin is a naturally-derived phytochemical which exhibits promising medicinal properties, including anticancer activities. In the present study, the anticancer potential of plumbagin has been demonstrated in lung cancer cells by targeting reactive oxygen species (ROS) and the intrinsic mitochondrial apoptotic pathway. Plumbagin showed impressive cytotoxic, anti-proliferative, and anti-migratory activities with IC₅₀ 3.10 ± 0.5 μM and 4.10 ± 0.5 μM in A549 and NCI-H522 cells, respectively. Plumbagin treatment significantly reduced the size of A549 tumor spheroids in a concentration-dependent manner. Plumbagin enhanced ROS production and arrested lung cancer cells in S and G2/M phase. Expression of antioxidant genes such as glutathione S-transferase P1 and superoxide dismutase-2 were found to be upregulated with plumbagin treatment in A549 cells. Plumbagin induced dissipation in mitochondrial membrane potential and affected the expression of intrinsic apoptotic pathway proteins. Increased expression of cytochrome c promotes the activation of pro-apoptotic protein Bax with decreased expression of anti-apoptotic protein Bcl-2. Further, plumbagin activated the mitochondrial downstream pathway protein caspase-9 and caspase-3 leading to apoptosis of A549 cells. Collectively, plumbagin could be a promising future phytotherapeutic candidate for lung cancer treatment via targeting intrinsic mitochondrial apoptotic pathway and ROS.

Targeting ROS-Mediated Crosstalk Between Autophagy and Apoptosis in Cancer

The control of crosstalk between autophagy and apoptosis in tumor cells can remove a critical barrier to comprehensive and efficacious treatment for cancer. Reactive oxygen species (ROS), by-products of redox homeostasis, are critical for regulating the balance between autophagy and apoptosis in cancer cells upon different drug treatments and gene modifications. The mechanisms and consequences involved in ROS-mediated crosstalk between apoptosis and autophagy are extremely complex in cancer cells. Here, we mainly discuss the closely linked relationship between ROS levels, autophagy, and apoptosis in cancer therapy.

Autophagy and its potent modulators from phytochemicals in cancer treatment

Autophagy is a ubiquitous catabolic process by which damaged or harmful intracellular components are delivered to the lysosomes for self-digestion and recycling. It is critical in cancer treatment. Therapy-induced autophagy predominantly acts as a pro-survival mechanism, but progressive autophagy can lead to non-apoptotic cell death, also known as autophagic cell death. Plants or herbs contain various natural compounds that are widely used in the treatment of many types of malignancies. Emerging evidence indicates that phytochemicals targeting the autophagic pathway are promising agents for cancer treatment. However, these compounds play different roles in autophagy. In this review, we discussed the role of autophagy in cancer development and therapy, and focussed on elucidating the anti-cancer activities of autophagic modulators, especially phytochemicals. Notably, we described a novel premise that the dynamic role of phytochemicals should be evaluated in regulation of autophagy in cancer.