Autophagy Modulation in Cancer: Current Knowledge on Action and Therapy

Homogeneous Polyporus polysaccharide exerts anti-bladder cancer effects via autophagy induction

CONTEXT

Polyporus polysaccharide (PPS), the leading bioactive ingredient extracted from Polyporus umbellatus (Pers.) Fr. (Polyporaceae), has been demonstrated to exert anti-bladder cancer and immunomodulatory functions in macrophages.

OBJECTIVE

To explore the effects of homogeneous Polyporus polysaccharide (HPP) on the proliferation and autophagy of bladder cancer cells co-cultured with macrophages.

MATERIALS AND METHODS

MB49 bladder cancer cells and RAW264.7 macrophages were co-cultured with or without HPP intervention (50, 100, or 200 μg/mL) for 24 h. The cell counting kit-8 (CCK-8) assay and 5-ethynyl-2″-deoxyuridine (EdU) staining evaluated MB49 cell proliferation. Monodansylcadaverine (MDC) staining and transmission electron microscopy (TEM) observed autophagosomes. Western blotting detected the expression levels of autophagy-related proteins and PI3K/Akt/mTOR pathway proteins.

RESULTS

HPP inhibited the proliferation of MB49 cells co-cultured with RAW264.7 cells but not MB49 cells alone. HPP altered the expression of autophagy-related proteins and promoted the formation of autophagosomes in MB49 cells in the co-culture system. Autophagy inhibitors 3-methyladenine (3-MA) and chloroquine (CQ) not only antagonized HPP-induced autophagy but also attenuated the inhibitory effects of HPP on MB49 cell proliferation in the co-culture system. HPP or RAW264.7 alone was not sufficient to induce autophagy in MB49 cells. In addition, HPP suppressed the protein expression of the PI3K/Akt/mTOR pathway in MB49 cells in the co-culture system.

DISCUSSION AND CONCLUSIONS

HPP induced bladder cancer cell autophagy by regulating macrophages in the co-culture system, resulting in the inhibition of cancer cell proliferation. The PI3K/Akt/mTOR pathway was involved in HPP-induced autophagy in the co-culture system.

FHL2 promotes the aggressiveness of lung adenocarcinoma by inhibiting autophagy via activation of the PI3K/AKT/mTOR pathway

BACKGROUND

Increasing evidence indicates that four and a half LIM domains 2 (FHL2) plays a crucial role in the progression of various cancers. However, the biological functions and molecular mechanism of FHL2 in lung adenocarcinoma (LUAD) remain unclear.

METHODS

We evaluated the prognostic value of FHL2 in LUAD using public datasets and further confirmed its prognostic value with our clinical data. The biological functions of FHL2 in LUAD were evaluated by in vitro and in vivo experiments. Pathway analysis and rescue experiments were subsequently performed to explore the molecular mechanism by which FHL2 promoted the progression of LUAD.

RESULTS

FHL2 was upregulated in LUAD tissues compared to adjacent normal lung tissues, and FHL2 overexpression was correlated with unfavorable outcomes in patients with LUAD. FHL2 knockdown significantly suppressed the proliferation, migration and invasion of LUAD cells, while FHL2 overexpression had the opposite effect. Mechanistically, FHL2 upregulated the PI3K/AKT/mTOR pathway and subsequently inhibited autophagy in LUAD cells. The effects FHL2 on the proliferation, migration and invasion of LUAD cells are dependent on the inhibition of autophagy, as of induction autophagy attenuated the aggressive phenotype induced by FHL2 overexpression.

CONCLUSIONS

FHL2 promotes the progression of LUAD by activating the PI3K/AKT/mTOR pathway and subsequently inhibiting autophagy, which can be exploited as a potential therapeutic target for LUAD.

The regulatory role of autophagy between TAMs and tumor cells

Cancer has become a global public health problem and its harmful effects have received widespread attention. Conventional treatments such as surgical resection, radiotherapy and other techniques are applicable to clinical practice, but new drugs are constantly being developed and other therapeutic approaches, such as immunotherapy are being applied. In addition to studying the effects on individual tumor cells, it is important to explore the role of tumor microenvironment on tumor cell development since tumor cells do not exist alone but in the tumor microenvironment. In the tumor microenvironment, tumor cells are interconnected with other stromal cells and influence each other, among which tumor-associated macrophages (TAMs) are the most numerous immune cells. At the same time, it was found that cancer cells have different levels of autophagy from normal cells. In cancer therapy, the occurrence of autophagy plays an important role in promoting tumor cell death or inhibiting tumor cell death, and is closely related to the environment. Therefore, elucidating the regulatory role of autophagy between TAMs and tumor cells may be an important breakthrough, providing new perspectives for further research on antitumor immune mechanisms and improving the efficacy of cancer immunotherapy.

Autophagy modulation changes mechano-chemical sensitivity of T24 bladder cancer cells

Bladder cancer cells possess unique adaptive capabilities: shaped by their environment, cells face a complex chemical mixture of metabolites and xenobiotics accompanied by physiological mechanical cues. These responses might translate into resistance to chemotherapeutical regimens and can largely rely on autophagy. Considering molecules capable of rewiring tumor plasticity, compounds of natural origin promise to offer valuable options. Fungal derived metabolites, such as bafilomycin and wortmannin are widely acknowledged as autophagy inhibitors. Here, their potential to tune bladder cancer cells´ adaptability to chemical and physical stimuli was assessed. Additionally, dietary occurring mycotoxins were also investigated, namely deoxynivalenol (DON, 0.1-10 µM) and fusaric acid (FA, 0.1-1 mM). Endowing a Janus' face behavior, DON and FA are on the one side described as toxins with detrimental health effects. Concomitantly, they are also explored experimentally for selective pharmacological applications including anticancer activities. In non-cytotoxic concentrations, bafilomycin (BAFI, 1-10 nM) and wortmannin (WORT, 1 µM) modified cell morphology and reduced cancer cell migration. Application of shear stress and inhibition of mechano-gated PIEZO channels reduced cellular sensitivity to BAFI treatment (1 nM). Similarly, for FA (0.5 mM) PIEZO1 expression and inhibition largely aligned with the modulatory potential on cancer cells motility. Additionally, this study highlighted that the activity profile of compounds with similar cytotoxic potential (e.g. co-incubation DON with BAFI or FA with WORT) can diverge substantially in the regulation of cell mechanotransduction. Considering the interdependence between tumor progression and response to mechanical cues, these data promise to provide a novel viewpoint for the study of chemoresistance and associated pathways.

Application of Nanoparticles for Efficient Delivery of Quercetin in Cancer Cells

Quercetin (Qu, 3,5,7,3', 4'-pentahydroxyflavanone) is a natural polyphenol compound abundantly found in health food or plant-based products. In recent decades, Qu has gained significant attention in the food, cosmetic, and pharmaceutic industries owning to its wide beneficial therapeutic properties such as antioxidant, anti-inflammatory and anticancer activities. Despite the favorable roles of Qu in cancer therapy due to its numerous impacts on the cell signaling axis, its poor chemical stability and bioavailability, low aqueous solubility as well as short biological half-life have limited its clinical application. Recently, drug delivery systems based on nanotechnology have been developed to overcome such limitations and enhance the Qu biodistribution following administration. Several investigations have indicated that the nano-formulation of Qu enjoys more remarkable anticancer effects than its free form. Furthermore, incorporating Qu in various nano-delivery systems improved its sustained release and stability, extended its circulation time, enhanced its accumulation at target sites, and increased its therapeutic efficiency. The purpose of this study was to provide a comprehensive review of the anticancer properties of various Qu nano-formulation to augment their effects on different malignancies. Various targeting strategies for improving Qu delivery, including nanoliposomes, lipids, polymeric, micelle, and inorganic nanoparticle NPs, have been discussed in this review. The results of the current study illustrated that a combination of appropriate nano encapsulation approaches with tumor-oriented targeting delivery might lead to establishing QU nanoparticles that can be a promising technique for cancer treatment.

Natural Activators of Autophagy

Autophagy is the process by which cell contents, such as aggregated proteins, dysfunctional organelles, and cell structures are sequestered by autophagosome and delivered to lysosomes for degradation. As a process that allows the cell to get rid of non-functional components that tend to accumulate with age, autophagy has been associated with many human diseases. In this regard, the search for autophagy activators and the study of their mechanism of action is an important task for treatment of many diseases, as well as for increasing healthy life expectancy. Plants are rich sources of autophagy activators, containing large amounts of polyphenolic compounds in their composition, which can be autophagy activators in their original form, or can be metabolized by the intestinal microbiota to active compounds. This review is devoted to the plant-based autophagy activators with emphasis on the sources of their production, mechanism of action, and application in various diseases. The review also describes companies commercializing natural autophagy activators.

Synthetic Activators of Autophagy

Autophagy is a central process for degradation of intracellular components that do not operate correctly. Molecular mechanisms underlying this process are extremely difficult to study, since they involve a large number of participants. The main task of autophagy is redistribution of cellular resources in response to environmental changes, such as starvation. Recent studies show that autophagy regulation could be the key to achieve healthy longevity, as well as to create therapeutic agents for treatment of neurodegenerative diseases such as Parkinson's and Alzheimer's diseases. Thus, development of autophagy activators with established detailed mechanism of action is a really important area of research. Several commercial companies are at various stages of development of such molecules, and some of them have already begun to introduce autophagy activators to the market.

Itraconazole halts hepatocellular carcinoma progression by modulating sonic hedgehog signaling in rats: A novel therapeutic approach

Liver cancer stands as the fourth leading global cause of death, and its prognosis remains grim due to the limited effectiveness of current medical interventions. Among the various pathways implicated in the development of hepatocellular carcinoma (HCC), the hedgehog signaling pathway has emerged as a crucial player. Itraconazole, a relatively safe and cost-effective antifungal medication, has gained attention for its potential as an anticancer agent. Its primary mode of action involves inhibiting the hedgehog pathway, yet its impact on HCC has not been elucidated. The main objective of this study was to investigate the effect of itraconazole on diethylnitrosamine-induced early-stage HCC in rats. Our findings revealed that itraconazole exhibited a multifaceted arsenal against HCC by downregulating the expression of key components of the hedgehog pathway, shh, smoothened (SMO), and GLI family zinc finger 1 (GLI1), and GLI2. Additionally, itraconazole extended survival and improved liver tissue structure, attributed mainly to its inhibitory effects on hedgehog signaling. Besides, itraconazole demonstrated a regulatory effect on Notch1, and Wnt/β-catenin signaling molecules. Consequently, itraconazole displayed diverse anticancer properties, including anti-inflammatory, antiangiogenic, antiproliferative, and apoptotic effects, as well as the potential to induce autophagy. Moreover, itraconazole exhibited a promise to impede the transformation of epithelial cells into a more mesenchymal-like phenotype. Overall, this study emphasizes the significance of targeting the hedgehog pathway with itraconazole as a promising avenue for further exploration in clinical studies related to HCC treatment.

The role and implication of autophagy in cholangiocarcinoma

Cholangiocarcinoma (CCA) is a malignant tumor that originates from the biliary epithelial cells. It is characterized by a difficult diagnosis and limited treatment options. Autophagy is a cellular survival mechanism that maintains nutrient and energy homeostasis and eliminates intracellular pathogens. It is involved in various physiological and pathological processes, including the development of cancer. However, the role, mechanism, and potential therapeutic targets of autophagy in CCA have not been thoroughly studied. In this review, we introduce the classification, characteristics, process, and related regulatory genes of autophagy. We summarize the regulation of autophagy on the progression of CCA and collect the latest research progress on some autophagy modulators with clinical potential in CCA. In conclusion, combining autophagy modulators with immunotherapy, chemotherapy, and targeted therapy has great potential in the treatment of CCA. This combination may be a potential therapeutic target for CCA in the future.

Elsinochrome A induces cell apoptosis and autophagy in photodynamic therapy

Elsinochrome A (EA) is a perylene quinone natural photosensitizer, photosensitizer under light excitation generates reactive oxygen species (ROS) to induce apoptosis, so can be used for treating tumors, that is so-called photodynamic therapy (PDT). However, the molecular mechanism, especially related to apoptosis and autophagy, is still unclear. In this study, we aimed to explore the mechanism of EA-PDT-induced B16 cells apoptosis and autophagy. The action of EA-PDT on mitochondrial permeability transition pore (MPTP), mitochondrial membrane potential (MMP) and the mitochondrial function were researched by fluorescence technique and Extracellular Flux Analyzer. Illumina sequencing, tandem mass tags Quantitative Proteomics and Western Blot studied the mechanism at the gene and protein levels. The results indicated that EA-PDT had excellent phototoxicity in vitro. EA could bind to the mitochondria. EA-PDT for 5 min caused MPTP opening, MMP decreasing and abnormal mitochondrial function with a concentration-dependent characteristic. EA-PDT resulted in an increase intracellular ROS and the number of autophagosomes. Caspase2, caspase9 and tnf were upregulated, and bcl2, prkn, atg2, atg9 and atg10 were downregulated. Our results indicated that EA-PDT induced cell apoptosis and autophagy through the mediation of ROS/Atg/Parkin. This study can provide enlightenment for exploring potential targets of drug development for the PDT of melanoma.

Autophagy-related proteins: Potential diagnostic and prognostic biomarkers of aging-related diseases

Autophagy plays a key role in cellular, tissue and organismal homeostasis and in the production of the energy load needed at critical times during development and in response to nutrient shortage. Autophagy is generally considered as a pro-survival mechanism, although its deregulation has been linked to non-apoptotic cell death. Autophagy efficiency declines with age, thus contributing to many different pathophysiological conditions, such as cancer, cardiomyopathy, diabetes, liver disease, autoimmune diseases, infections, and neurodegeneration. Accordingly, it has been proposed that the maintenance of a proper autophagic activity contributes to the extension of the lifespan in different organisms. A better understanding of the interplay between autophagy and risk of age-related pathologies is important to propose nutritional and life-style habits favouring disease prevention as well as possible clinical applications aimed at promoting long-term health.

Delineating the twin role of autophagy in lung cancer

Autophagy represents an intracellular defense mechanism equipped within each eukaryotic cells to enable them to cope with variety of physical, chemical, and biological stresses. This mechanism helps to restore the homeostasis and preserve the cellular integrity and function of the cells. In these conditions, such as hypoxia, nutrient deprivation, inhibition of protein synthesis or microbial attack, the process of autophagy is upregulated to maintain cellular homeostasis. The role of autophagy in cancer is an intriguing topic which needs further exploration. This process of autophagy has been many times referred as a double-edged sword in the process of tumorigenesis. In the initial stages, it may act as a tumor suppressor and enable to quench the damaged organelles and harmful molecules generated. In more advanced stages, autophagy has been shown to act as a tumor-promoting system as it may help the cancer cells to cope better with stressful microenvironments. Besides this, autophagy has been associated with development of resistance to anticancer drugs as well as promoting the immune evasion in cancer cells, representing a serious obstacle in cancer treatment and its outcome. Also, autophagy is associated with hallmarks of cancer that may lead to activation of invasion and metastasis. The information on this twin role needs further exploration and deeper understanding of the pathways involved. In this review, we discuss the various aspects of autophagy during tumor development, from early to late stages of tumor growth. Both the protective role of autophagy in preventing tumor growth and the underlying mechanisms adopted with evidence from past studies have been detailed. Further, the role of autophagy in conferring resistance to distinct lung cancer treatment and immune shielding properties has also been discussed. This is essential for further improving on treatment outcome and success rates.

Lnc-ing epigenetic mechanisms with autophagy and cancer drug resistance

Long noncoding RNAs (lncRNAs) comprise a diverse class of RNA molecules that regulate various physiological processes and have been reported to be involved in several human pathologies ranging from neurodegenerative disease to cancer. Therapeutic resistance is a major hurdle for cancer treatment. Over the past decade, several studies has emerged on the role of lncRNAs in cancer drug resistance and many trials have been conducted employing them. LncRNAs also regulate different cell death pathways thereby maintaining a fine balance of cell survival and death. Autophagy is a complex cell-killing mechanism that has both cytoprotective and cytotoxic roles. Similarly, autophagy can lead to the induction of both chemosensitization and chemoresistance in cancer cells upon therapeutic intervention. Recently the role of lncRNAs in the regulation of autophagy has also surfaced. Thus, lncRNAs can be used in cancer therapeutics to alleviate the challenges of chemoresistance by targeting the autophagosomal axis. In this chapter, we discuss about the role of lncRNAs in autophagy-mediated cancer drug resistance and its implication in targeted cancer therapy.

Manassantin A inhibits tumour growth under hypoxia through the activation of chaperone-mediated autophagy by modulating Hsp90 activity

BACKGROUND

Chaperon-mediated autophagy (CMA) has taken on a new emphasis in cancer biology. However, the roles of CMA in hypoxic tumours are poorly understood. We investigated the anti-tumour effects of the natural product ManA through the activation of CMA in tumour progression under hypoxia.

METHODS

The effect of ManA on CMA activation was assessed in mouse xenograft models and cells. The gene expressions of HIF-1α, HSP90AA1, and transcription factor EB (TFEB) were analysed using The Cancer Genome Atlas (TCGA) datasets to assess the clinical relevance of CMA.

RESULTS

ManA activates photoswitchable CMA reporter activity and inhibits Hsp90 chaperone function by disrupting the Hsp90/F1F0-ATP synthase complex. Hsp90 inhibition enhances the interaction between CMA substrates and LAMP-2A and TFEB nuclear localisation, suggesting CMA activation by ManA. ManA-activated CMA retards tumour growth and displays cooperative anti-tumour activity with anti-PD-1 antibody. TCGA datasets show that a combined expression of HSP90AA1High/HIF1AHigh or TFEBLow/HIF1AHigh is strongly correlated with poor prognosis in patients with lung cancer.

CONCLUSIONS

ManA-induced CMA activation by modulating Hsp90 under hypoxia induces HIF-1α degradation and reduces tumour growth. Thus, inducing CMA activity by targeting Hsp90 may be a promising therapeutic strategy against hypoxic tumours.

Targeting Autophagy Using Long Non-Coding RNAs (LncRNAs): New Landscapes in the Arena of Cancer Therapeutics

Cancer has become a global health hazard accounting for 10 million deaths in the year 2020. Although different treatment approaches have increased patient overall survival, treatment for advanced stages still suffers from poor clinical outcomes. The ever-increasing prevalence of cancer has led to a reanalysis of cellular and molecular events in the hope to identify and develop a cure for this multigenic disease. Autophagy, an evolutionary conserved catabolic process, eliminates protein aggregates and damaged organelles to maintain cellular homeostasis. Accumulating evidence has implicated the deregulation of autophagic pathways to be associated with various hallmarks of cancer. Autophagy exhibits both tumor-promoting and suppressive effects based on the tumor stage and grades. Majorly, it maintains the cancer microenvironment homeostasis by promoting viability and nutrient recycling under hypoxic and nutrient-deprived conditions. Recent investigations have discovered long non-coding RNAs (lncRNAs) as master regulators of autophagic gene expression. lncRNAs, by sequestering autophagy-related microRNAs, have been known to modulate various hallmarks of cancer, such as survival, proliferation, EMT, migration, invasion, angiogenesis, and metastasis. This review delineates the mechanistic role of various lncRNAs involved in modulating autophagy and their related proteins in different cancers.

Magnolol induces cytotoxic autophagy in glioma by inhibiting PI3K/AKT/mTOR signaling

Glioma is difficult-to-treat because of its infiltrative nature and the presence of the blood-brain barrier. Temozolomide is the only FDA-approved drug for its management. Therefore, finding a novel chemotherapeutic agent for glioma is of utmost importance. Magnolol, a neolignan, has been known for its apoptotic role in glioma. In this work, we have explored a novel anti-glioma mechanism of Magnolol associated with its role in autophagy modulation. We found increased expression levels of Beclin-1, Atg5-Atg12, and LC3-II and lower p62 expression in Magnolol-treated glioma cells. PI3K/AKT/mTOR pathway proteins were also downregulated in Magnolol-treated glioma cells. Next, we treated the glioma cells with Insulin, a stimulator of PI3K/AKT/mTOR signaling, to confirm that Magnolol induced autophagy by inhibiting this pathway. Insulin reversed the effect on Magnolol-mediated autophagy induction. We also established the same in in vivo glioma model where Magnolol showed an anti-glioma effect by inducing autophagy. To confirm the cytotoxic effect of Magnolol-induced autophagy, we used Chloroquine, a late-stage autophagy inhibitor. Chloroquine efficiently reversed the anti-glioma effects of Magnolol both in vitro and in vivo. Our study revealed the cytotoxic effect of Magnolol-induced autophagy in glioma, which was not previously reported. Additionally, Magnolol showed no toxicity in non-cancerous cell lines as well as rat organs. Thus, we concluded that Magnolol is an excellent candidate for developing new therapeutic strategies for glioma management.

Autophagy: Dual roles and perspective for clinical treatment of colorectal cancer

Colorectal cancer (CRC) raises concerns to people because of its high recurrence and metastasis rate, diagnosis challenges, and poor prognosis. Various studies have shown the association of altered autophagy with tumorigenesis, tumor-stroma interactions, and resistance to cancer therapy in CRC. Autophagy is a highly conserved cytosolic catabolic process in eukaryotes that plays distinct roles in CRC occurrence and progression. In early tumorigenesis, autophagy may inhibit tumor growth through diverse mechanisms, whereas it exhibits a tumor promoting function in CRC progression. This different functions of autophagy in CRC occurrence and progression make developing therapies targeting autophagy complicated. In this review, we discuss the classification and process of autophagy as well as its dual roles in CRC, functions in the tumor microenvironment, cross-talk with apoptosis, and potential usefulness as a CRC therapeutic target.

Galectins and galectin-mediated autophagy regulation: new insights into targeted cancer therapy

Galectins are animal lectins with specific affinity for galactosides via the conserved carbohydrate recognition domains. Increasing studies recently have identified critical roles of galectin family members in tumor progression. Abnormal expression of galectins contributes to the proliferation, metastasis, epithelial-mesenchymal transformation (EMT), immunosuppression, radio-resistance and chemoresistance in various cancers, which has attracted cumulative clinical interest in galectin-based cancer treatment. Galectin family members have been reported to participate in autophagy regulation under physiological conditions and in non-tumoral diseases, and implication of galectins in multiple processes of carcinogenesis also involves regulation of autophagy, however, the relationship between galectins, autophagy and cancer remains largely unclear. In this review, we introduce the structure and function of galectins at the molecular level, summarize their engagements in autophagy and cancer progression, and also highlight the regulation of autophagy by galectins in cancer as well as the therapeutic potentials of galectin and autophagy-based strategies. Elaborating on the mechanism of galectin-regulated autophagy in cancers will accelerate the exploitation of galectins-autophagy targeted therapies in treatment for cancer.

The significance of the crosstalk between ubiquitination or deubiquitination and ncRNAs in non-small cell lung cancer

Lung cancer (LC) remains the leading cause of cancer-related deaths worldwide, with extremely high morbidity and mortality rates. Non-small cell lung cancer (NSCLC) is the most critical type of LC. It seriously threatens the life and health of patients because of its early metastasis, late clinical symptoms, limited early screening methods, and poor treatment outcomes. Non-coding RNAs (ncRNAs), including microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs), participate in cell proliferation, metastasis, and chemoresistance. Several previous studies have proven that ncRNAs are vital regulators of tumorigenesis. Ubiquitination plays the most crucial role in protein post-translational modification (PTM). Deubiquitination and ubiquitination form a homeostasis. In summary, ubiquitination and deubiquitination play essential roles in mediating the degradation or overexpression of a range of crucial proteins in various cancers. A growing number of researchers have found that interactions between ncRNAs and ubiquitination (or deubiquitination) play a crucial role in NSCLC. This review presents several typical examples of the important effects of ncRNAs and ubiquitination (or deubiquitination) in NSCLC, aiming to provide more creative ideas for exploring the diagnosis and treatment of NSCLC.

Evaluation of the Effectiveness of Various Autophagy Inhibitors in A549 Cancer Stem Cells

Numerous studies have already established that autophagy plays a central role in the survival of all cells, including malignant ones. Autophagy is a central cog in the general mechanism that provides the intracellular proteostasis determining cellular physiological and phenotypic characteristics. The accumulated data show that autophagy largely contributes to cancer cell stemness. Thus, autophagy modulation is considered one of the promising pharmacological targets in therapy aimed at cancer stem cell elimination. However, autophagy is a multi-stage intracellular process that involves numerous protein participants. In addition, the process can be activated simultaneously by various signaling modules. Therefore, it is no small feat to select an effective pharmacological drug against autophagy. What's more, the search for potential chemotherapeutic agents that could eliminate cancer stem cells through pharmacological inhibition of autophagy is still under way. In the present work, we selected a panel of autophagy inhibitors (Autophinib, SBI-0206965, Siramesine, MRT68921, and IITZ-01), some of whom have been recently identified as effective autophagy inhibitors in cancer cells. Using A549 cancer cells, which express the core stem factors Oct4 and Sox2, we evaluated the effect of these drugs on the survival and preservation of the original properties of cancer stem cells. Among the agents selected, only Autophinib demonstrated a significant toxic effect on cancer stem cells. The obtained results demonstrate that autophagy inhibition by Autophinib downregulates the expression of the Sox2 protein in A549 cells, and that this downregulation correlates with a pronounced induction of apoptosis. Moreover, Autophinib-treated A549 cells are unable to form spheroids, which indicates a reduction in stemness. Thus, among the drugs studied, only Autophinib can be considered a potential agent against cancer stem cells.

An Antidepressant Drug Increased TRAIL Receptor-2 Expression and Sensitized Lung Cancer Cells to TRAIL-induced Apoptosis

BACKGROUND

TRAIL has emerged as a promising therapeutic target due to its ability to selectively induce apoptosis in cancer cells while sparing normal cells. Autophagy, a highly regulated cellular recycling mechanism, is known to play a cell survival role by providing a required environment for the cell. Recent studies suggest that autophagy plays a significant role in increasing TRAIL resistance in certain cancer cells. Thus, regulating autophagy in TRAIL-mediated cancer therapy is crucial for its role in cancer treatment.

OBJECTIVE

Our study explored whether the antidepressant drug desipramine could enhance the ability of TRAIL to kill cancer cells by inhibiting autophagy.

METHODS

The effect of desipramine on TRAIL sensitivity was examined in various lung cancer cell lines. Cell viability was measured by morphological analysis, trypan blue exclusion, and crystal violet staining. Flow cytometry analysis was carried out to measure apoptosis with annexin V-PI stained cells. Western blotting, rtPCR, and immunocytochemistry were carried out to measure autophagy and death receptor expression. TEM was carried out to detect autophagy inhibition.

RESULTS

Desipramine treatment increased the TRAIL sensitivity in all lung cancer cell lines. Mechanistically, desipramine treatment induced death receptor expression to increase TRAIL sensitivity. This effect was confirmed when the genetic blockade of DR5 reduced the effect of desipramine in enhanced TRAIL-mediated cell death. Further investigation revealed that desipramine treatment increased the LC3 and p62 levels, indicating the inhibition of lysosomal degradation of autophagy. Notably, TRAIL, in combination with either desipramine or the autophagy inhibitor chloroquine, exhibited enhanced cytotoxicity compared to TRAIL treatment alone.

CONCLUSION

Our findings revealed the potential of desipramine to induce TRAIL-mediated cell death by autophagy impairment. This discovery suggests its therapeutic potential for inducing TRAIL-mediated cell death by increasing the expression of death receptors, which is caused by impairing autophagy.

Health horizons: Future trends and technologies from the European Medicines Agency's horizon scanning collaborations

In medicines development, the progress in science and technology is accelerating. Awareness of these developments and their associated challenges and opportunities is essential for medicines regulators and others to translate them into benefits for society. In this context, the European Medicines Agency uses horizon scanning to shine a light on early signals of relevant innovation and technological trends with impact on medicinal products. This article provides the results of systematic horizon scanning exercises conducted by the Agency, in collaboration with the World Health Organization (WHO) and the European Commission's Joint Research Centre's (DG JRC). These collaborative exercises aim to inform policy-makers of new trends and increase preparedness in responding to them. A subset of 25 technological trends, divided into three clusters were selected and reviewed from the perspective of medicines regulators. For each of these trends, the expected impact and challenges for their adoption are discussed, along with recommendations for developers, regulators and policy makers.

DSTYK inhibition increases the sensitivity of lung cancer cells to T cell-mediated cytotoxicity

Lung cancer remains the leading cause of cancer-related death worldwide. We identify DSTYK, a dual serine/threonine and tyrosine non-receptor protein kinase, as a novel actionable target altered in non-small cell lung cancer (NSCLC). We also show DSTYK's association with a lower overall survival (OS) and poorer progression-free survival (PFS) in multiple patient cohorts. Abrogation of DSTYK in lung cancer experimental systems prevents mTOR-dependent cytoprotective autophagy, impairs lysosomal biogenesis and maturation, and induces accumulation of autophagosomes. Moreover, DSTYK inhibition severely affects mitochondrial fitness. We demonstrate in vivo that inhibition of DSTYK sensitizes lung cancer cells to TNF-α-mediated CD8+-killing and immune-resistant lung tumors to anti-PD-1 treatment. Finally, in a series of lung cancer patients, DSTYK copy number gain predicts lack of response to the immunotherapy. In summary, we have uncovered DSTYK as new therapeutic target in lung cancer. Prioritization of this novel target for drug development and clinical testing may expand the percentage of NSCLC patients benefiting from immune-based treatments.

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.

TOLLIP Protein Expression Predicts Unfavorable Outcome in Renal Cell Carcinoma

Resistance to systemic therapy is one of the hallmarks of renal cell carcinoma (RCC). Recently, TOLLIP has emerged as a possible driver of autophagy and chemoresistance. We explored the relationship between primary and metastatic RCC tumor characteristics, patient survival, and TOLLIP expression. The tissue microarrays cohort contained 95 cores of the primary tumor, matched metastases, and matched adjacent tissues derived from 32 RCC patients. TOLLIP expression in tumor samples was evaluated using the H-score. All examined samples showed cytoplasmic TOLLIP expression, with a median value of 100 in primary tumors, 107.5 in metastases, and 220 in the control group. The expression was significantly higher in the normal adjacent tissues compared to primary or metastatic RCC (p < 0.05). We found a positive correlation between expressions of TOLLIP in the primary tumor and its metastases (p < 0.05; k = 0.48). TOLLIP expression significantly correlates with a lower overall survival rate (p = 0.047). TOLLIP functions as a ubiquitin-LC3 adaptor in the intracellular pathway associated with autophagy. Relative TOLLIP overexpression may augment autophagy-related signaling, limiting susceptibility to therapy. The blockade of TOLLIP physiological function seems to be a promising approach to overcoming resistance to systemic therapy.

Microglia autophagy in ischemic stroke: A double-edged sword

Ischemic stroke (IS) is one of the major types of cerebrovascular diseases causing neurological morbidity and mortality worldwide. In the pathophysiological process of IS, microglia play a beneficial role in tissue repair. However, it could also cause cellular damage, consequently leading to cell death. Inflammation is characterized by the activation of microglia, and increasing evidence showed that autophagy interacts with inflammation through regulating correlative mediators and signaling pathways. In this paper, we summarized the beneficial and harmful effects of microglia in IS. In addition, we discussed the interplay between microglia autophagy and ischemic inflammation, as along with its application in the treatment of IS. We believe this could help to provide the theoretical references for further study into IS and treatments in the future.

Sodium cantharidate promotes autophagy in breast cancer cells by inhibiting the PI3K-Akt-mTOR signaling pathway

Sodium cantharidate (SCA) is a derivative of cantharidin obtained by its reaction with alkali. Studies have shown that it inhibits the occurrence and progression of several cancers. However, therapeutic effects of SCA on breast cancer are less well studied. This study aimed to clarify the effect of SCA on breast cancer cells and its mechanism, and to provide a scientific basis for the clinical use of SCA for the treatment of breast cancer. The results of cell counting kit-8, colony formation assay, and 5-ethynyl-2'-deoxyuridine staining showed that SCA inhibited breast cancer cell proliferation. Wound-healing and transwell assays demonstrated that SCA inhibited the migration and invasion of breast cancer cells. Transmission electron microscopy revealed that SCA induced autophagy in breast cancer cells. RNA sequencing technology showed that SCA significantly regulated the phosphoinositide 3-kinase-Akt-mammalian target of rapamycin (PI3K-Akt-mTOR) pathway, which was further verified using western blotting. The inducing effect of SCA on breast cancer autophagy was reversed by the mTOR activator MHY1485. In addition, subcutaneous xenograft experiments confirmed that SCA significantly inhibited tumor growth in vivo. Hematoxylin-eosin, TdT-mediated dUTP nick-end labeling, and immunohistochemical staining indicated that SCA induced tumor cell autophagy and apoptosis in nude mice without causing organ damage. In summary, we found that SCA promoted breast cancer cell apoptosis by inhibiting the PI3K-Akt-mTOR pathway and inducing autophagy.

Targeting Both Autophagy and Immunotherapy in Breast Cancer Treatment

As clinical efforts towards breast-conserving therapy and prolonging survival of those with metastatic breast cancer increase, innovative approaches with the use of biologics are on the rise. Two areas of current focus are cancer immunotherapy and autophagy, both of which have been well-studied independently but have recently been shown to have intertwining roles in cancer. An increased understanding of their interactions could provide new insights that result in novel diagnostic, prognostic, and therapeutic strategies. In this breast cancer-focused review, we explore the interactions between autophagy and two clinically relevant immune checkpoint pathways; the programmed cell death-1 receptor with its ligand (PD-L1)/PD-1 and the cytotoxic T-lymphocyte-associated protein 4 (CTLA-4)/CD80 and CD86 (B7-1 and B7-2). Furthermore, we discuss emerging preclinical and clinical data supporting targeting both immunotherapy and autophagy pathway manipulation as a promising approach in the treatment of breast cancer.

The global research and emerging trends in autophagy of pancreatic cancer: A bibliometric and visualized study

Objective

To present the global research features and hotspots, and forecast the emerging trends by conducting a bibliometric analysis based on literature related to autophagy of pancreatic cancer from 2011 to 2022.

Methods

The literature data regarding autophagy of pancreatic cancer were retrieved and downloaded from the Web of Science Core Collection (WOSCC) from Clarivate Analytics on June 10th, 2022. VOSviewer (version 1.6.18) was used to perform the bibliometric analysis.

Results

A total of 616 studies written by 3993 authors, covered 45 countries and 871 organizations, published in 263 journals and co-cited 28152 references from 2719 journals. China (n=260, 42.2%) and the United States (n=211, 34.3%) were the most frequent publishers and collaborated closely. However, publications from China had a low average number of citations (25.35 times per paper). The output of University of Texas MD Anderson Cancer Center ranked the first with 26 papers (accounting for 4.2% of the total publications). Cancers (n=23, 3.7%; Impact Factor = 6.639) published most papers in this field and was very pleasure to accept related researches. Daolin Tang and Rui Kang published the most papers (n=18, respectively). The research hotspots mainly focused on the mechanisms of autophagy in tumor onset and progression, the role of autophagy in tumor apoptosis, and autophagy-related drugs in treating pancreatic cancer (especially combined therapy). The emerging topics were chemotherapy resistance mediated by autophagy, tumor microenvironment related to autophagy, autophagy-depended epithelial-mesenchymal transition (EMT), mitophagy, and the role of autophagy in tumor invasion.

Conclusion

Attention has been increasing in autophagy of pancreatic cancer over the past 12 years. Our results undoubtedly provide scholars with new clues and ideas in this field.

Prognostic relevance of autophagy-related markers p62, LC3, and Beclin1 in ovarian cancer

AIM

To analyze the expression of autophagy markers p62, LC3, and Beclin1 in ovarian cancer tissue and evaluate the prognostic potential of these markers.

METHODS

The study enrolled 328 patients: 122 with epithelial ovarian carcinoma, 42 with atypical proliferative tumor, and 164 with benign epithelial ovarian tumor. The expression of p62, LC3, and Beclin1 was analyzed in central and invasive tumor segments with immunohistochemistry combined with tissue microarray. The expression levels of the analyzed markers were correlated with relevant histopathology parameters.

RESULTS

The expression of all analyzed markers was most remarkable in epithelial ovarian carcinoma. There was a strong positive correlation between the expressions of p62 and LC3, while these two markers negatively correlated with Beclin1. High-grade serous carcinoma had higher p62 and LC3 levels, and lower Beclin1 levels than other tumor types. This expression profile was also observed in more advanced tumor stages.

CONCLUSION

Prominent p62 and LC3 expression in combination with weak Beclin1 expression in high-grade serous carcinoma indicates potential for the application of autophagy inhibitors in patients with this tumor subtype.

Integration of the Connectivity Map and Pathway Analysis to Predict Plant Extract’s Medicinal Properties—The Study Case of Sarcopoterium spinosum L

Medicinal properties of plants are usually identified based on knowledge of traditional medicine or using low-throughput screens for specific pharmacological activities. The former is very biased since it requires prior knowledge of plants’ properties, while the latter depends on a specific screening system and will miss medicinal activities not covered by the screen. We sought to enrich our understanding of the biological activities of Sarcopoterium spinosum L. root extract based on transcriptome changes to uncover a plurality of possible pharmacological effects without the need for prior knowledge or functional screening. We integrated Gene Set Enrichment Analysis of the RNAseq data to identify pathways affected by the treatment of cells with the extract and perturbational signatures in the CMAP database to enhance the validity of the results. Activities of signaling pathways were measured using immunoblotting with phospho-specific antibodies. Mitochondrial membrane potential was assessed using JC-1 staining. SARS-CoV-2-induced cell killing was assessed in Vero E6 and A549 cells using an MTT assay. Here, we identified transcriptome changes following exposure of cultured cells to the medicinal plant Sarcopoterium spinosum L. root extract. By integrating algorithms of GSEA and CMAP, we confirmed known anti-cancer activities of the extract and predicted novel biological effects on oxidative phosphorylation and interferon pathways. Experimental validation of these pathways uncovered strong activation of autophagy, including mitophagy, and excellent protection from SARS-CoV-2 infection. Our study shows that gene expression analysis alone is insufficient for predicting biological effects since some of the changes reflect compensatory effects, and additional biochemical tests provide necessary corrections. This study defines the advantages and limitations of transcriptome analysis in predicting the biological and medicinal effects of the Sarcopoterium spinosum L. extract. Such analysis could be used as a general approach for predicting the medicinal properties of plants.

The cross-talk of autophagy and apoptosis in breast carcinoma: implications for novel therapies?

Breast cancer is still the most common cancer in women worldwide. Resistance to drugs and recurrence of the disease are two leading causes of failure in treatment. For a more efficient treatment of patients, the development of novel therapeutic regimes is needed. Recent studies indicate that modulation of autophagy in concert with apoptosis induction may provide a promising novel strategy in breast cancer treatment. Apoptosis and autophagy are two tightly regulated distinct cellular processes. To maintain tissue homeostasis abnormal cells are disposed largely by means of apoptosis. Autophagy, however, contributes to tissue homeostasis and cell fitness by scavenging of damaged organelles, lipids, proteins, and DNA. Defects in autophagy promote tumorigenesis, whereas upon tumor formation rapidly proliferating cancer cells may rely on autophagy to survive. Given that evasion of apoptosis is one of the characteristic hallmarks of cancer cells, inhibiting autophagy and promoting apoptosis can negatively influence cancer cell survival and increase cell death. Hence, combination of antiautophagic agents with the enhancement of apoptosis may restore apoptosis and provide a therapeutic advantage against breast cancer. In this review, we discuss the cross-talk of autophagy and apoptosis and the diverse facets of autophagy in breast cancer cells leading to novel models for more effective therapeutic strategies.

Therapeutic Aspects and Molecular Targets of Autophagy to Control Pancreatic Cancer Management

Pancreatic cancer (PC) begins within the organ of the pancreas, which produces digestive enzymes, and is one of the formidable cancers for which appropriate treatment strategies are urgently needed. Autophagy occurs in the many chambers of PC tissue, including cancer cells, cancer-related fibroblasts, and immune cells, and can be fine-tuned by various promotive and suppressive signals. Consequently, the impacts of autophagy on pancreatic carcinogenesis and progression depend greatly on its stage and conditions. Autophagy inhibits the progress of preneoplastic damage during the initial phase. However, autophagy encourages tumor formation during the development phase. Several studies have reported that both a tumor-promoting and a tumor-suppressing function of autophagy in cancer that is likely cell-type dependent. However, autophagy is dispensable for pancreatic ductal adenocarcinoma (PDAC) growth, and clinical trials with autophagy inhibitors, either alone or in combination with other therapies, have had limited success. Autophagy’s dual mode of action makes it therapeutically challenging despite autophagy inhibitors providing increased longevity in medical studies, highlighting the need for a more rigorous review of current findings and more precise targeting strategies. Indeed, the role of autophagy in PC is complicated, and numerous factors must be considered when transitioning from bench to bedside. In this review, we summarize the evidence for the tumorigenic and protective role of autophagy in PC tumorigenesis and describe recent advances in the understanding of how autophagy may be regulated and controlled in PDAC.

STAT3 suppresses the AMPKα/ULK1-dependent induction of autophagy in glioblastoma cells

Despite advances in molecular characterization, glioblastoma (GBM) remains the most common and lethal brain tumour with high mortality rates in both paediatric and adult patients. The signal transducer and activator of transcription 3 (STAT3) is an important oncogenic driver of GBM. Although STAT3 reportedly plays a role in autophagy of some cells, its role in cancer cell autophagy remains unclear. In this study, we found Serine-727 and Tyrosine-705 phosphorylation of STAT3 was constitutive in GBM cell lines. Tyrosine phosphorylation of STAT3 in GBM cells suppresses autophagy, whereas knockout (KO) of STAT3 increases ULK1 gene expression, increases TSC2-AMPKα-ULK1 signalling, and increases lysosomal Cathepsin D processing, leading to the stimulation of autophagy. Rescue of STAT3-KO cells by the enforced expression of wild-type (WT) STAT3 reverses these pathways and inhibits autophagy. Conversely, expression of Y705F- and S727A-STAT3 phosphorylation deficient mutants in STAT3-KO cells did not suppress autophagy. Inhibition of ULK1 activity (by treatment with MRT68921) or its expression (by siRNA knockdown) in STAT3-KO cells inhibits autophagy and sensitizes cells to apoptosis. Taken together, our findings suggest that serine and tyrosine phosphorylation of STAT3 play critical roles in STAT3-dependent autophagy in GBM, and thus are potential targets to treat GBM.

Overexpression of TP53INP2 Promotes Apoptosis in Clear Cell Renal Cell Cancer via Caspase-8/TRAF6 Signaling Pathway

Clear cell renal cell cancer (ccRCC) is a tumor of high malignancy, which can escape apoptosis. The tumor protein p53-inducible nuclear protein 2 (TP53INP2), known as an autophagy protein, is the essential part for autophagosome formation and sensitizes cells to apoptosis. Our study is aimed at exploring the role of TP53INP2 in ccRCC. We have identified the autophagy-related genes (ARGs) of differential expression in ccRCC patients with the help of the TCGA database by bioinformatics analysis. Our assays of quantitative real-time polymerase chain reaction (qRT-PCR) and western blot were for the determination on the both levels of mRNA and protein. Overexpression of TP53INP2 on cellular proliferation, migration, and apoptosis of ccRCC was verified in the ways of performing CCK-8, wound scrape, transwell and flow cytometry assays in vitro, and a mice tumor model in vivo. Transmission electron microscopy was used to measure autophagy formation. The underlying mechanisms of TP53INP2 on ccRCC were determined via coimmunoprecipitation. TP53INP2 was found highly associated with an outcome of worse overall survival (OS) in Kaplan-Meier curves, and this parameter in ccRCC tissues was also lower than the normal tissues. Overexpression of TP53INP2 inhibited ccRCC cellular proliferation, migration, and invasion, as well as the tumor growth of mice. Those cells treated with autophagy inhibitor chloroquine (CQ) or TP53INP2 increased the apoptosis rate. TP53INP2 promoted autophagy formation and elevated the ratio of LC3 II/LC3 I. However, TP53INP2 did not significantly decrease the p-mTOR level. In addition, TP53INP2 activates the expressions of caspase-3, caspase-8, and PARP. Caspase-8 and TNF receptor associated factor 6 (TRAF6) were found to bind to each other in the presence of TP53INP2. TP53INP2 induces apoptosis in ccRCC cells through caspase-8/TRAF6 pathway, rather than the autophagy-dependent pathway.

Inhibition of TLR7 and TLR9 Reduces Human Cholangiocarcinoma Cell Proliferation and Tumor Development

BACKGROUND

Toll-like receptors (TLRs) are key players in innate immunity and modulation of TLR signaling has been demonstrated to profoundly affect proliferation and growth in different types of cancer. However, the role of TLRs in human intrahepatic cholangiocarcinoma (ICC) pathogenesis remains largely unexplored.

AIMS

We set out to determine if TLRs play any role in ICCs which could potentially make them useful treatment targets.

METHODS

Tissue microarrays containing samples from 9 human ICCs and normal livers were examined immunohistochemically for TLR4, TLR7, and TLR9 expression. Proliferation of human ICC cell line HuCCT1 was measured by MTS assay following treatment with CpG-ODN (TLR9 agonist), imiquimod (TLR7 agonist), chloroquine (TLR7 and TLR9 inhibitor) and IRS-954 (TLR7 and TLR9 antagonist). The in vivo effects of CQ and IRS-954 on tumor development were also examined in a NOD-SCID mouse xenograft model of human ICC.

RESULTS

TLR4 was expressed in all normal human bile duct epithelium but absent in the majority (60%) of ICCs. TLR7 and TLR9 were expressed in 80% of human ICCs. However, TLR7 was absent in all cases of normal human bile duct epithelium and only one was TLR9 positive. HuCCT1 cell proliferation in vitro significantly increased following IMQ or CpG-ODN treatment (P < 0.03 and P < 0.002, respectively) but decreased with CQ (P < 0.02). In the mouse xenograft model there was significant reduction in size of tumors from CQ and IRS-954 treated mice compared to untreated controls.

CONCLUSION

TLR7 and TLR9 should be further explored for their potential as actionable targets in the treatment of ICC.

Autophagy in Cancer Cell Transformation; A Potential Novel Therapeutic Strategy

Abstract:

Basal autophagy plays a crucial role in maintaining intracellular homeostasis and prevents the cell from escaping the cell cycle regulation mechanisms and being cancerous. Mitophagy and nucleophagy are essential for cell health. Autophagy plays a pivotal role in cancer cell transformation, where upregulated precancerous autophagy induces apoptosis. Impaired autophagy has been shown to upregulate cancer cell transformation. However, tumor cells upregulate autophagy to escape elimination and survive the unfavorable conditions and resistance to chemotherapy. Cancer cells promote autophagy through modulation of autophagy regulation mechanisms and increase expression of the autophagy-related genes. Whereas, autophagy regulation mechanisms involved microRNAs, transcription factors, and the internalized signaling pathways such as AMPK, mTOR, III PI3K and ULK-1. Disrupted regulatory mechanisms are various as the cancer cell polymorphism. Targeting a higher level of autophagy regulation is more effective, such as gene expression, transcription factors, or epigenetic modification that are responsible for up-regulation of autophagy in cancer cells. Currently, the CRISPR-CAS9 technique is available and can be applied to demonstrate the potential effects of autophagy in cancerous cells.

Targeting regulated cell death (RCD) with small-molecule compounds in triple-negative breast cancer: a revisited perspective from molecular mechanisms to targeted therapies

Triple-negative breast cancer (TNBC) is a subtype of human breast cancer with one of the worst prognoses, with no targeted therapeutic strategies currently available. Regulated cell death (RCD), also known as programmed cell death (PCD), has been widely reported to have numerous links to the progression and therapy of many types of human cancer. Of note, RCD can be divided into numerous different subroutines, including autophagy-dependent cell death, apoptosis, mitotic catastrophe, necroptosis, ferroptosis, pyroptosis and anoikis. More recently, targeting the subroutines of RCD with small-molecule compounds has been emerging as a promising therapeutic strategy, which has rapidly progressed in the treatment of TNBC. Therefore, in this review, we focus on summarizing the molecular mechanisms of the above-mentioned seven major RCD subroutines related to TNBC and the latest progress of small-molecule compounds targeting different RCD subroutines. Moreover, we further discuss the combined strategies of one drug (e.g., narciclasine) or more drugs (e.g., torin-1 combined with chloroquine) to achieve the therapeutic potential on TNBC by regulating RCD subroutines. More importantly, we demonstrate several small-molecule compounds (e.g., ONC201 and NCT03733119) by targeting the subroutines of RCD in TNBC clinical trials. Taken together, these findings will provide a clue on illuminating more actionable low-hanging-fruit druggable targets and candidate small-molecule drugs for potential RCD-related TNBC therapies.

Targeting lncRNAs in programmed cell death as a therapeutic strategy for non-small cell lung cancer

Lung cancer is a leading cause of cancer-related mortality worldwide, with non-small cell lung cancer (NSCLC) being the most common histological type. Owing to the limited therapeutic efficacy and side effects of currently available therapies for NSCLC, it is necessary to identify novel therapeutic targets for NSCLC. Long non-coding RNAs (lncRNAs) are non-protein-coding RNAs with a transcript length of more than 200 nucleotides, which play a vital role in the tumorigenesis and progression of multiple cancers, including NSCLC. Induction of programmed cell death (PCD) is the main mechanism leading to tumour cell death in most cancer treatments. Recent studies have demonstrated that lncRNAs are closely correlated with PCD including apoptosis, pyroptosis, autophagy and ferroptosis, which can regulate PCD and relevant death pathways to affect NSCLC progression and the efficacy of clinical therapy. Therefore, in this review, we focused on the function of lncRNAs in PCD of NSCLC and summarized the therapeutic role of targeting lncRNAs in PCD for NSCLC treatment, aiming to provide new sights into the underlying pathogenic mechanisms and propose a potential new strategy for NSCLC therapy so as to improve therapeutic outcomes with the ultimate goal to benefit the patients.

A Risk-Scoring Model Based on Evaluation of Ferroptosis-Related Genes in Osteosarcoma

Background

Osteosarcoma (OS) is a bone malignancy frequently seen in pediatrics and has high mortality and incidence. Ferroptosis is an important cell death process in regulating the apoptosis and invasion of tumor cells, so constructing the risk-scoring model based on OS ferroptosis-related genes (FRGs) will benefit the evaluation of both treatment and prognosis.

Methods

The OS dataset was screened from the Therapeutically Applicable Research to Generate Effective Treatments (TARGET) database, and OS-related FRGs were found through the Ferroptosis Database (FerrDb) using a multivariate Cox regression model, followed by the generation of the risk scores and a risk-scoring prediction model. Further systematical exploration for immune cell infiltration and assessing the prediction of response to targeted drugs was conducted.

Results

Based on OS-related FRGs, a risk-scoring model of FRGs in OS was constructed. The six FRGs played a role in the carbon metabolism, glutathione metabolism, and pentose phosphate pathways. Results from targeted drug sensitivity analyses were concordant to pathway analyses. The response to targeted drugs statistically differed between the two groups with different risks, and the high-risk group presented a high sensitivity to targeted drugs.

Conclusions

We identified a 6-ferroptosis-gene-based prognostic signature in OS and created and verified a risk-scoring model to predict the prognosis of OS at 1, 3, and 5 years for OS patients independently.

Autophagy Agents in Clinical Trials for Cancer Therapy: A Brief Review

Autophagy has been of novel interest since it was first demonstrated to have effect in Burkitt’s lymphoma. Since that time, the autophagy agents chloroquine and hydroxychloroquine have become the only FDA (Food and Drug Administration)-approved autophagy inhibitors. While not approved for cancer therapy, there are ongoing clinical trials to evaluate their safety and efficacy. Pevonedistat has emerged as a novel inhibitor through the neddylation pathway and is an autophagy activator. This paper summarizes and presents current clinical trials for hydroxychloroquine (HCQ), chloroquine (CQ), and Pevonedistat for the clinician.

Engineering Nanoplatform for Combined Cancer Therapeutics via Complementary Autophagy Inhibition

Despite advances in the development of tumor treatments, mortality from cancer continues to increase. Nanotechnology is expected to provide an innovative anti-cancer therapy, to combat challenges such as multidrug resistance and tumor recurrence. Nevertheless, tumors can greatly rely on autophagy as an alternative source for metabolites, and which desensitizes cancer cells to therapeutic stress, hindering the success of any current treatment paradigm. Autophagy is a conserved process by which cells turn over their own constituents to maintain cellular homeostasis. The multistep autophagic pathway provides potentially druggable targets to inhibit pro-survival autophagy under various therapeutic stimuli. In this review, we focus on autophagy inhibition based on functional nanoplatforms, which may be a potential strategy to increase therapeutic sensitivity in combinational cancer therapies, including chemotherapy, radiotherapy, phototherapy, sonodynamic therapy, and immunotherapy.

Deglycosylated EpCAM regulates proliferation by enhancing autophagy of breast cancer cells via PI3K/Akt/mTOR pathway

Autophagy is an important regulator of cellular homeostasis and its dysregulation often results in cancer. Aberrant glycosylation induced by oncogenic transformation contributes to tumor invasion and metastasis. In a previous study, we have demonstrated that EpCAM, a glycosylation protein, is associated with cell growth and metastasis in breast cancer. But the effect of EpCAM glycosylation on autophagy is not clear. the precise mechanism of regulation remains largely unknown. In this study, breast cancer cells were transfected with N-glycosylation mutation EpCAM plasmid to express deglycosylated EpCAM. The result showed that deglycosylated EpCAM promoted autophagy in breast cancer cells. We further confirmed this conclusion with the activator (Rapamycin, RAP) and inhibitor (Wortmannin) of autophagy. We also found that deglycosylated EpCAM promoted apoptosis and inhibited proliferation through activating autophagy by suppressing Akt/mTOR signaling pathway in breast cancer cells. These findings represent a novel mechanism by which deglycosylated EpCAM inhibits proliferation by enhancing autophagy of breast cancer cells via PI3K/Akt/mTOR pathway. In conclusion, the combination of autophagy modulation and EpCAM targeted therapy is a promising therapeutic strategy in the treatment of breast cancer.

Autophagy ATG16L1 rs2241880 impacts the colorectal cancer risk: A case-control study

Background

Despite many efforts to discover the important role of the autophagy process in the pathogenesis of colorectal cancer (CRC), the exact involved molecular mechanism still remains to be elucidated. Recently, a limited number of studies have been employed to discover the impact of autophagy genes’ variants on the development and progression of CRC. Here, we evaluated the association between two single‐nucleotide polymorphisms (SNPs) in the main components of the autophagy genes, ATG16L1 rs2241880, and ATG5 rs1475270, and the CRC risk in an Iranian population.

Methods

During this investigation, a total of 369 subjects, including 179 CRC patients and 190 non‐cancer controls have been genotyped using Tetra‐primer amplification refractory mutation system‐polymerase chain reaction (TP‐ARMS‐PCR) method.

Result

The results demonstrated that the T allele of the ATG16L1 rs2241880 was significantly associated with the increased risk of CRC in the studied population (OR 1.64, 95% CI: 1.21–2.22, p = 0.0015). Moreover, ATG16L1 rs2241880 TT genotype increased the susceptibility to CRC (OR 3.31, 95% CI: 1.64–6.69, p = 0.0008). Furthermore, a significant association was observed under the recessive and dominant inheritance models (p = 0.0015 and p = 0.017, respectively). No statistically significant differences were found in the ATG5 rs1475270 alleles and genotypes between the cases and controls.

Conclusion

The results of the present study may be helpful concerning the risk stratification in CRC patients based on the genotyping approach of autophagy pathways and emphasize the need for further investigations among different populations and ethnicities to refine our conclusions.

Role of autophagy in gastric carcinogenesis

Gastric cancer represents a common and highly fatal malignancy, and thus a pathophysiology-based reconsideration is necessary, given the absence of efficient therapeutic regimens. In this regard, emerging data reveal a significant role of autophagy in gastric oncogenesis, progression, metastasis and chemoresistance. Although autophagy comprises a normal primordial process, ensuring cellular homeostasis under energy depletion and stress conditions, alterations at any stage of the complex regulatory system could stimulate a tumorigenic and promoting cascade. Among others, Helicobacter pylori infection induces a variety of signaling molecules modifying autophagy, during acute infection or after chronic autophagy degeneration. Subsequently, defective autophagy allows malignant transformation and upon cancer establishment, an overactive autophagy is stimulated. This overexpressed autophagy provides energy supplies and resistance mechanisms to gastric cancer cells against hosts defenses and anticancer treatment. This review interprets the implicated autophagic pathways in normal cells and in gastric cancer to illuminate the potential preventive, therapeutic and prognostic benefits of understanding and intervening autophagy.

Emerging roles of autophagy in the development and treatment of urothelial carcinoma of the bladder

INTRODUCTION

High recurrence rates, frequent surveillance strategies, and current multidisciplinary treatment approaches make urothelial carcinoma of bladder (UCB) one of the most expensive cancers to clinically manage. Recent studies have demonstrated a role for autophagy in bladder tumorigenesis. It serves as a tumor suppressor by maintaining genomic integrity and preventing tumor proliferation during initial stages of tumor development. Nevertheless, once established, cancer cells may utilize protective autophagy to endure cellular stress and survive in the adverse environment. Its excessive stimulation supports cancer cells' resistance to therapeutic modalities.

AREAS COVERED

PubMed and Google Scholar electronic databases were searched for recently published studies. This review summarizes emerging roles of autophagy in development/progression of UCB and treatment resistance and explores novel therapeutic targets for prevention of cancer invasion, metastatic spread', and disease relapse.

EXPERT OPINION

The development of novel therapies via targeting of autophagy may augment current treatment regimens and improve clinical outcomes. Synthetic compounds or plant-based metabolites are reported to enhance cancer therapies by modulating autophagic flux. Successful autophagy-focused therapeutic intervention requires a mechanistic understanding of autophagic effects on tumor initiation and progression and the development of efficient biomarkers to monitor it in tumor tissues.

Hydroxychloroquine induces oxidative DNA damage and mutation in mammalian cells

Since the early stages of the pandemic, hydroxychloroquine (HCQ), a widely used drug with good safety profile in clinic, has come to the forefront of research on drug repurposing for COVID-19 treatment/prevention. Despite the decades-long use of HCQ in the treatment of diseases, such as malaria and autoimmune disorders, the exact mechanisms of action of this drug are only beginning to be understood. To date, no data are available on the genotoxic potential of HCQ in vitro or in vivo. The present study is the first investigation of the DNA damaging- and mutagenic effects of HCQ in mammalian cells in vitro, at concentrations that are comparable to clinically achievable doses in patient populations. We demonstrate significant induction of a representative oxidative DNA damage (8-oxodG) in primary mouse embryonic fibroblasts (MEFs) treated with HCQ at 5 and 25 μM concentrations (P = 0.020 and P = 0.029, respectively), as determined by enzyme-linked immunosorbent assay. Furthermore, we show significant mutagenicity of HCQ, manifest as 2.2- and 1.8-fold increases in relative cII mutant frequency in primary and spontaneously immortalized Big Blue® MEFs, respectively, treated with 25 μM dose of this drug (P = 0.005 and P = 0.012, respectively). The observed genotoxic effects of HCQ in vitro, achievable at clinically relevant doses, are novel and important, and may have significant implications for safety monitoring in patient populations. Given the substantial number of the world's population receiving HCQ for the treatment of various chronic diseases or in the context of clinical trials for COVID-19, our findings warrant further investigations into the biological consequences of therapeutic/preventive use of this drug.

Natural compounds in the regulation of proteostatic pathways: An invincible artillery against stress, ageing, and diseases

Cells have different sets of molecules for performing an array of physiological functions. Nucleic acids have stored and carried the information throughout evolution, whereas proteins have been attributed to performing most of the cellular functions. To perform these functions, proteins need to have a unique conformation and a definite lifespan. These attributes are achieved by a highly coordinated protein quality control (PQC) system comprising chaperones to fold the proteins in a proper three-dimensional structure, ubiquitin-proteasome system for selective degradation of proteins, and autophagy for bulk clearance of cell debris. Many kinds of stresses and perturbations may lead to the weakening of these protective cellular machinery, leading to the unfolding and aggregation of cellular proteins and the occurrence of numerous pathological conditions. However, modulating the expression and functional efficiency of molecular chaperones, E3 ubiquitin ligases, and autophagic proteins may diminish cellular proteotoxic load and mitigate various pathological effects. Natural medicine and small molecule-based therapies have been well-documented for their effectiveness in modulating these pathways and reestablishing the lost proteostasis inside the cells to combat disease conditions. The present article summarizes various similar reports and highlights the importance of the molecules obtained from natural sources in disease therapeutics.

UBE2T promotes autophagy via the p53/AMPK/mTOR signaling pathway in lung adenocarcinoma

Background

Ubiquitin-conjugating enzyme E2T (UBE2T) acts as an oncogene in various types of cancer. However, the mechanisms behind its oncogenic role remain unclear in lung cancer. This study aims to explore the function and clinical relevance of UBE2T in lung cancer.

Methods

Lentiviral vectors were used to mediate UBE2T depletion or overexpress UBE2T in lung cancer cells. CCK8 analysis and western blotting were performed to investigate the effects of UBE2T on proliferation, autophagy, and relevant signaling pathways. To exploit the clinical significance of UBE2T, we performed immunohistochemistry staining with an anti-UBE2T antibody on 131 NSCLC samples. Moreover, we downloaded the human lung adenocarcinoma (LUAD) dataset from The Cancer Atlas Project (TCGA). Lasso Cox regression model was adopted to establish a prognostic model with UBE2T-correlated autophagy genes.

Results

We found that UBE2T stimulated proliferation and autophagy, and silencing this gene abolished autophagy in lung cancer cells. As suggested by Gene set enrichment analysis, we observed that UBE2T downregulated p53 levels in A549 cells and vice versa. Blockade of p53 counteracted the inhibitory effects of UBE2T depletion on autophagy. Meanwhile, the AMPK/mTOR signaling pathway was activated during UBE2T-mediated autophagy, suggesting that UBE2T promotes autophagy via the p53/AMPK/mTOR pathway. Interestingly, UBE2T overexpression increased cisplatin-trigged autophagy and led to cisplatin resistance of A549 cells, whereas inhibiting autophagy reversed drug resistance. However, no association was observed between UEB2T and overall survival in a population of 131 resectable NSCLC patients. Therefore, we developed and validated a multiple gene signature by considering UBE2T and its relevance in autophagy in lung cancer. The risk score derived from the prognostic signature significantly stratified LUAD patients into low- and high-risk groups with different overall survival. The risk score might independently predict prognosis. Interestingly, nomogram and decision curve analysis demonstrated that the signature’s prognostic accuracy culminated while combined with clinical features. Finally, the risk score showed great potential in predicting clinical chemosensitivity.

Conclusions

We found that UBE2T upregulates autophagy in NSCLC cells by activating the p53/AMPK/mTOR signaling pathway. The clinical predicting ability of UBE2T in LUAD can be improved by considering the autophagy-regulatory role of UBE2T.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-021-03056-1.

Steroidal Saponins Isolated from the Rhizome of Dioscorea tokoro Inhibit Cell Growth and Autophagy in Hepatocellular Carcinoma Cells

Our preliminary screening identified an extract from the rhizome of Dioscorea tokoro, which strongly suppressed the proliferation of HepG2 hepatocellular carcinoma cells and inhibited autophagy. This study aimed to isolate active compounds from the rhizome of D. tokoro that exert antiproliferative effects and inhibit autophagy. The bioassay-guided fractionation of the active fraction led to the isolation of two spirostan-type steroidal saponins, dioscin (1) and yamogenin 3-O-α-l-rhamnopyranosyl (1→4)-O-α-l-rhamnopyranosyl(1→2)-β-d-glucopyranoside (2), and the frostane-type steroidal saponin protodioscin (3) from the n-BuOH fraction. Furthermore, acid hydrolysis of 1 and 2 produced the aglycones diosgenin (4) and yamogenin (5), respectively. Compounds 1-5 suppressed proliferation of HepG2 cells. The analysis of structure-activity relationships indicated that the 25(R)-conformation, structures with a sugar moiety, and the spirostan-type aglycone moiety contributed to antiproliferative activity. Analysis of autophagy-related proteins demonstrated that 1-3 clearly increased the levels of both LC3-II and p62, implying that 1-3 deregulate the autophagic pathway by blocking autophagic flux, which results in p62 and LC3-II accumulation. In contrast, 1-3 did not significantly affect caspase-3 activation and PARP cleavage, suggesting that the antiproliferative activity of 1-3 occurred independently of caspase-3-mediated apoptosis. In summary, our study showed that 1-3, active compounds in the rhizome of D. tokoro, suppressed cell proliferation and autophagy, and might be potential agents for autophagy research and cancer chemoprevention.