Autophagy Modulation in Cancer: Current Knowledge on Action and Therapy

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.

Autophagy-Related Three-Gene Prognostic Signature for Predicting Survival in Esophageal Squamous Cell Carcinoma

Esophageal squamous cell carcinoma (ESCC) is one of the most aggressive malignant tumors in China, and its prognosis remains poor. Autophagy is an evolutionarily conserved catabolic process involved in the occurrence and development of ESCC. In this study, we described the expression profile of autophagy-related genes (ARGs) in ESCC and developed a prognostic prediction model for ESCC patients based on the expression pattern of ARGs. We used four ESCC cohorts, GSE53624 (119 samples) set as the discovery cohort, The Cancer Genome Atlas (TCGA) ESCC set (95 samples) as the validation cohort, 155 ESCC cohort, and Oncomine cohort were used to screen and verify differentially expressed ARGs. We identified 34 differentially expressed genes out of 222 ARGs. In the discovery cohort, we divided ESCC patients into three groups that showed significant differences in prognosis. Then, we analyzed the prognosis of 34 differentially expressed ARGs. Three genes [poly (ADP-ribose) polymerase 1 (PARP1), integrin alpha-6 (ITGA6), and Fas-associated death domain (FADD)] were ultimately obtained through random forest feature selection and were constructed as an ARG-related prognostic model. This model was further validated in TCGA ESCC set. Cox regression analysis confirmed that the three-gene signature was an independent prognostic factor for ESCC patients. This signature effectively stratified patients in both discovery and validation cohorts by overall survival (P = 5.162E-8 and P = 0.052, respectively). We also constructed a clinical nomogram with a concordance index of 0.713 to predict the survival possibility of ESCC patients by integrating clinical characteristics and the ARG signature. The calibration curves substantiated fine concordance between nomogram prediction and actual observation. In conclusion, we constructed a new ARG-related prognostic model, which shows the potential to improve the ability of individualized prognosis prediction in ESCC.

c-FLIP regulates autophagy by interacting with Beclin-1 and influencing its stability

c-FLIP (cellular FLICE-like inhibitory protein) protein is mostly known as an apoptosis modulator. However, increasing data underline that c-FLIP plays multiple roles in cellular homoeostasis, influencing differently the same pathways depending on its expression level and isoform predominance. Few and controversial data are available regarding c-FLIP function in autophagy. Here we show that autophagic flux is less effective in c-FLIP−/− than in WT MEFs (mouse embryonic fibroblasts). Indeed, we show that the absence of c-FLIP compromises the expression levels of pivotal factors in the generation of autophagosomes. In line with the role of c-FLIP as a scaffold protein, we found that c-FLIP_L interacts with Beclin-1 (BECN1: coiled-coil, moesin-like BCL2-interacting protein), which is required for autophagosome nucleation. By a combination of bioinformatics tools and biochemistry assays, we demonstrate that c-FLIP_L interaction with Beclin-1 is important to prevent Beclin-1 ubiquitination and degradation through the proteasomal pathway. Taken together, our data describe a novel molecular mechanism through which c-FLIP_L positively regulates autophagy, by enhancing Beclin-1 protein stability.

PFKFB3 Inhibition Impairs Erlotinib-Induced Autophagy in NSCLCs

Tyrosine kinase inhibitors (TKIs) targeting the kinase domain of the epidermal growth factor receptor (EGFR), such as erlotinib, have dramatically improved clinical outcomes of patients with EGFR-driven non-small cell lung carcinomas (NSCLCs). However, intrinsic or acquired resistance remains a clinical barrier to the success of FDA-approved EGFR TKIs. Multiple mechanisms of resistance have been identified, including the activation of prosurvival autophagy. We have previously shown that the expression and activity of PFKFB3—a known driver of glycolysis—is associated with resistance to erlotinib and that PFKFB3 inhibition improves the response of NSCLC cells to erlotinib. This study focuses on investigating the role of PFKFB3 in regulating erlotinib-driven autophagy to escape resistance to erlotinib. We evaluated the consequence of pharmacological inhibition of PFKFB3 on erlotinib-driven autophagy in NSCLC cells with different mutation statuses. Here, we identify PFKFB3 as a mediator of erlotinib-induced autophagy in NSCLCs. We demonstrate that PFKFB3 inhibition sensitizes NCSLCs to erlotinib via impairing autophagy flux. In summary, our studies uncovered a novel crosstalk between PFKFB3 and EGFR that regulates erlotinib-induced autophagy, thus contributing to erlotinib sensitivity in NSCLCs.

A macrolide from Streptomyces sp. modulates apoptosis and autophagy through Mcl-1 downregulation in human breast cancer cells

Secondary metabolites in marine organisms exhibit various pharmacological activities against diseases, such as cancer. In this study, the anti-proliferative effect of JBIR-100, a macrolide isolated from Streptomyces sp., was investigated in breast cancer cells. Cell growth was inhibited in response to JBIR-100 treatment concentration- and time-dependently in both MCF-7 and MDA-MB-231 breast cancer cells. JBIR-100 caused apoptosis, as verified by caspase activation and the cleavage of PARP. Western blotting revealed that JBIR-100 modulated the expression of Akt/NF-κB signaling components and Bcl-2 family members. Overexpression of Mcl-1 partially rescued MCF-7 cells from JBIR-100-induced cytotoxicity. In addition, transmission electron microscopy analyses, confocal analysis, and western blot assay indicated that JBIR-100 inhibited autophagy in MCF-7 cells. Exposure to the autophagy inhibitor did not synergize JBIR-100-induced apoptosis. In summary, our results suggested that JBIR-100 may be potentially used for breast cancer therapy.

Genome-Wide Identification of Autophagy Prognostic Signature in Pancreatic Cancer

Background:

Autophagy plays a vital role in cancer development. However, there is currently no comprehensive study regarding the effects of autophagy-related genes (ARGs) on pancreatic cancer prognosis. Thus, this study aimed to establish an autophagy-related signature for predicting the prognosis of patients with pancreatic cancer.

Methods:

We identified and validated differentially-expressed ARGs using data from The Cancer Genome Atlas (TCGA) database, Genotype-Tissue Expression project (GTEx) and Expression Omnibus (GEO) database. We performed Cox proportional hazards regression analysis on the differentially-expressed ARGs to develop an autophagy-related signature. We tested the expression of these genes through western blotting and verified their prognostic values through gene expression profiling and interactive analyses (GEPIA).

Results:

We identified a total of 21 differentially-expressed ARGs and screened 4 OS-related ARGs (TP63, RAB24, APOL1, and PTK6). Both the training and validation sets showed that the autophagy-related signature was more accurate than the Tumor Node Metastasis (TNM) staging system. Moreover, the western blotting result showed that the expression of TP63, APOL1, and PTK6 was high, whereas that of RAB24 was low in cancer tissues.

Conclusion:

This 4-ARG signature might potentially help in providing personalized therapy to patients with cancer.

The Sex-Related Interplay between TME and Cancer: On the Critical Role of Estrogen, MicroRNAs and Autophagy

The interplay between cancer cells and the tumor microenvironment (TME) has a fundamental role in tumor progression and response to therapy. The plethora of components constituting the TME, such as stroma, fibroblasts, endothelial and immune cells, as well as macromolecules, e.g., hormones and cytokines, and epigenetic factors, such as microRNAs, can modulate the survival or death of cancer cells. Actually, the TME can stimulate the genetically regulated programs that the cell puts in place under stress: apoptosis or, of interest here, autophagy. However, the implication of autophagy in tumor growth appears still undefined. Autophagy mainly represents a cyto-protective mechanism that allows cell survival but, in certain circumstances, also leads to the blocking of cell cycle progression, possibly leading to cell death. Since significant sex/gender differences in the incidence, progression and response to cancer therapy have been widely described in the literature, in this review, we analyzed the roles played by key components of the TME, e.g., estrogen and microRNAs, on autophagy regulation from a sex/gender-based perspective. We focused our attention on four paradigmatic and different forms of cancers-colon cancer, melanoma, lymphoma, and lung cancer-concluding that sex-specific differences may exert a significant impact on TME/cancer interaction and, thus, tumor growth.

The Role of Ceramide Metabolism and Signaling in the Regulation of Mitophagy and Cancer Therapy

Simple Summary

Sphingolipids are membrane-associated lipids that are involved in signal transduction pathways regulating cell death, growth, and migration. In cancer cells, sphingolipids regulate pathways relevant to cancer therapy, such as invasion, metastasis, apoptosis, and lethal mitophagy. Notable sphingolipids include ceramide, a sphingolipid that induces death and lethal mitophagy, and sphingosine-1 phosphate, a sphingolipid that induces survival and chemotherapeutic resistance. These sphingolipids participate in regulating the process of mitophagy, where cells encapsulate damaged mitochondria in double-membrane vesicles (called autophagosomes) for degradation. Lethal mitophagy is an anti-tumorigenic mechanism mediated by ceramide, where cells degrade many mitochondria until the cancer cell dies in an apoptosis-independent manner.

Abstract

Sphingolipids are bioactive lipids responsible for regulating diverse cellular functions such as proliferation, migration, senescence, and death. These lipids are characterized by a long-chain sphingosine backbone amide-linked to a fatty acyl chain with variable length. The length of the fatty acyl chain is determined by specific ceramide synthases, and this fatty acyl length also determines the sphingolipid’s specialized functions within the cell. One function in particular, the regulation of the selective autophagy of mitochondria, or mitophagy, is closely regulated by ceramide, a key regulatory sphingolipid. Mitophagy alterations have important implications for cancer cell proliferation, response to chemotherapeutics, and mitophagy-mediated cell death. This review will focus on the alterations of ceramide synthases in cancer and sphingolipid regulation of lethal mitophagy, concerning cancer therapy.

Inhibition Effect of Chloroquine and Integrin-Linked Kinase Knockdown on Translation in Melanoma Cells

The twofold role of autophagy in cancer is often the therapeutic target. Numerous regulatory pathways are shared between autophagy and other molecular processes needed in tumorigenesis, such as translation or survival signaling. Thus, we have assumed that ILK knockdown should promote autophagy, and used together with chloroquine, an autophagy inhibitor, it could generate a better anticancer effect by dysregulation of common signaling pathways. Expression at the protein level was analyzed using Western Blot; siRNA transfection was done for ILK. Analysis of cell signaling pathways was monitored with phospho-specific antibodies. Melanoma cell proliferation was assessed with the crystal violet test, and migration was evaluated by scratch wound healing assays. Autophagy was monitored by the accumulation of its marker, LC3-II. Our data show that ILK knockdown by siRNA suppresses melanoma cell growth by inducing autophagy through AMPK activation, and simultaneously initiates apoptosis. We demonstrated that combinatorial treatment of melanoma cells with CQ and siILK has a stronger antitumor effect than monotherapy with either of these. It generates the synergistic antitumor effects by the decrease of translation of both global and oncogenic proteins synthesis. In our work, we point to the crosstalk between translation and autophagy regulation.

Ameliorative effects of colostrum against DMBA hepatotoxicity in rats

Colostrum, the sole diet for newborns, is an emerging nutraceutical. To date, the chemopreventive effect of Bovine Colostrum against liver injury induced by the potent carcinogen, 7,12-dimethyl-Benz[a]anthracene (DMBA) is unexplored. Humans are daily exposed to DMBA which is a highly lipophilic environmental organic pollutant. The study aimed to investigate the hepatoprotective role of Bovine Colostrum against DMBA-induced hepatotoxicity using a rat model. Fifty male rats were divided into five groups; GI (control), GII (olive oil, vehicle for DMBA), GIII (DMBA), GIV (DMBA + Bovine Colostrum), GV (Bovine Colostrum). After 12 weeks, body weight changes and mortality were calculated. Histological and ultrastructural examinations of liver tissue were performed. Expressions of p53, TGFβ2, TNF-α, S6K2, and c20orf20 were assessed by RT-PCR. Post-treatment with Bovine Colostrum increased both the body weight and the survival rate of rats treated with DMBA. In addition, remarkable protection against the pathological effect of DMBA was noted. Ultrastructurally, Bovine Colostrum ameliorated/prevented most of the toxic effects of DMBA on hepatocytes, including irregularities of nuclear envelope, clumping, and margination of heterochromatin aggregates, segregated nucleoli, and mitochondrial pleomorphism. Bovine Colostrum administration down-regulated p53, C20orf20, and S6K2 mRNA levels, and up-regulated TNF-α and TGFβ2. In conclusion, Bovine Colostrum have a protective effect against DMBA-induced toxicity on the liver of albino rats. Consequently, Bovine Colostrum may prevent polycyclic aromatic hydrocarbons-induced hepatotoxicity and may be useful in promoting human health if supplemented in the diet.

Is targeting autophagy mechanism in cancer a good approach? The possible double-edge sword effect

Autophagy is a conserved cellular process required to maintain homeostasis. The hallmark of autophagy is the formation of a phagophore that engulfs cytosolic materials for degradation and recycling to synthesize essential components. Basal autophagy is constitutively active under normal conditions and it could be further induced by physiological stimuli such as hypoxia, nutrient starvation, endoplasmic reticulum stress,energy depletion, hormonal stimulation and pharmacological treatment. In cancer, autophagy is highly context-specific depending on the cell type, tumour microenvironment, disease stage and external stimuli. Recently, the emerging role of autophagy as a double-edged sword in cancer has gained much attention. On one hand, autophagy suppresses malignant transformation by limiting the production of reactive oxygen species and DNA damage during tumour development. Subsequently, autophagy evolved to support the survival of cancer cells and promotes the tumourigenicity of cancer stem cells at established sites. Hence, autophagy is an attractive target for cancer therapeutics and researchers have been exploiting the use of autophagy modulators as adjuvant therapy. In this review, we present a summary of autophagy mechanism and controlling pathways, with emphasis on the dual-role of autophagy (double-edged sword) in cancer. This is followed by an overview of the autophagy modulation for cancer treatment and is concluded by a discussion on the current perspectives and future outlook of autophagy exploitation for precision medicine.

The role of autophagy in escaping therapy-induced polyploidy/senescence

Autophagy is an evolutionarily conserved process necessary to maintain cell homeostasis in response to various forms of stress such as nutrient deprivation and hypoxia as well as functioning to remove damaged molecules and organelles. The role of autophagy in cancer varies depending on the stage of cancer. Cancer therapeutics can also simultaneously evoke cancer cell senescence and ploidy increase. Both cancer cell senescence and polyploidization are reversible by depolyploidization giving rise to the progeny. Autophagy activation may be indispensable for cancer cell escape from senescence/polyploidy. As cancer cell polyploidy is proposed to be involved in cancer origin, the role of autophagy in polyploidization/depolyploidization of senescent cancer cells seems to be crucial. Accordingly, this review is an attempt to understand the complicated interrelationships between reversible cell senescence/polyploidy and autophagy.

Methyltransferase-like 1 regulates lung adenocarcinoma A549 cell proliferation and autophagy via the AKT/mTORC1 signaling pathway

Methyltransferase-like 1 (METTL1) is a transfer RNA and microRNA modifying enzyme. However, its role in lung adenocarcinoma (LUAD) remains unknown. The present study aimed to investigate the effect of METTL1 in LUAD and determine the association between METTL1 expression and prognosis of patients with LUAD. The expression profile of METTL1 in LUAD tissues was downloaded from public cancer databases and analyzed using the Gene Expression Profiling Interactive Analysis database and UALCAN online software. In addition, the association between METTL1 expression and prognosis of patients with LUAD was assessed using the Kaplan-Meier Plotter software. The effect of METTL1 in the A549 cell line was determined in vitro via overexpression and knockdown experiments. The results demonstrated that METTL1 was upregulated in LUAD tissues, and its increased expression was associated with unfavorable prognosis. Furthermore, METTL1 promoted proliferation and colony formation of A549 cells, and inhibited autophagy via the AKT/mechanistic target of rapamycin complex 1 signaling pathway. Taken together, the results of the present study suggest that METTL1 acts as an oncogene in LUAD, thus may be a potential prognostic predictor and therapeutic target for LUAD.

Autophagy Paradox of Cancer: Role, Regulation, and Duality

Autophagy, a catabolic process, degrades damaged and defective cellular materials through lysosomes, thus working as a recycling mechanism of the cell. It is an evolutionarily conserved and highly regulated process that plays an important role in maintaining cellular homeostasis. Autophagy is constitutively active at the basal level; however, it gets enhanced to meet cellular needs in various stress conditions. The process involves various autophagy-related genes that ultimately lead to the degradation of targeted cytosolic substrates. Many factors modulate both upstream and downstream autophagy pathways like nutritional status, energy level, growth factors, hypoxic conditions, and localization of p53. Any problem in executing autophagy can lead to various pathological conditions including neurodegeneration, aging, and cancer. In cancer, autophagy plays a contradictory role; it inhibits the formation of tumors, whereas, during advanced stages, autophagy promotes tumor progression. Besides, autophagy protects the tumor from various therapies by providing recycled nutrition and energy to the tumor cells. Autophagy is stimulated by tumor suppressor proteins, whereas it gets inhibited by oncogenes. Due to its dynamic and dual role in the pathogenesis of cancer, autophagy provides promising opportunities in developing novel and effective cancer therapies along with managing chemoresistant cancers. In this article, we summarize different strategies that can modulate autophagy in cancer to overcome the major obstacle, i.e., resistance developed in cancer to anticancer therapies.

Application of an Autophagy-Related Gene Prognostic Risk Model Based on TCGA Database in Cervical Cancer

Background: Autophagy plays an important role in the development of cancer. However, the prognostic value of autophagy-related genes (ARGs) in cervical cancer (CC) is unclear. The purpose of this study is to construct a survival model for predicting the prognosis of CC patients based on ARG signature.

Methods: ARGs were obtained from the Human Autophagy Database and Molecular Signatures Database. The expression profiles of ARGs and clinical data were downloaded from the TCGA database. Differential expression analysis of CC tissues and normal tissues was performed using R software to screen out ARGs with an aberrant expression. Univariate Cox, Lasso, and multivariate Cox regression analyses were used to construct a prognostic model which was validated by using the test set and the entire set. We also performed an independent prognostic analysis of risk score and some clinicopathological factors of CC. Finally, a clinical practical nomogram was established to predict individual survival probability.

Results: Compared with normal tissues, there were 63 ARGs with an aberrant expression in CC tissues. A risk model based on 3 ARGs was finally obtained by Lasso and Cox regression analysis. Patients with high risk had significantly shorter overall survival (OS) than low-risk patients in both train set and validation set. The ROC curve validated its good performance in survival prediction, suggesting that this model has a certain extent sensitivity and specificity. Multivariate Cox analysis showed that the risk score was an independent prognostic factor. Finally, we mapped a nomogram to predict 1-, 3-, and 5-year survival for CC patients. The calibration curves indicated that the model was reliable.

Conclusion: A risk prediction model based on CHMP4C, FOXO1, and RRAGB was successfully constructed, which could effectively predict the prognosis of CC patients. This model can provide a reference for CC patients to make precise treatment strategy.

Chlorpromazine, an antipsychotic agent, induces G2/M phase arrest and apoptosis via regulation of the PI3K/AKT/mTOR-mediated autophagy pathways in human oral cancer

Chlorpromazine (CPZ), an FDA-approved phenothiazine derivative used to treat schizophrenia and other psychiatric disorders, has been demonstrated to have potential anti-tumor effects. However, the potential effects of CPZ on human oral cancer cells and the underlying molecular mechanisms remain unknown. In this study, treatment of human oral cancer cells with CPZ inhibited their proliferation and induced G2/M phase arrest. Treatment with CPZ induced apoptosis through the extrinsic death receptor and the intrinsic mitochondrial pathways. In addition, the induction of autophagy was observed by the formation of autophagosomes, the expression of autophagy-related proteins and activation of the PI3K/Akt/mTOR/p70S6K pathway. The CPZ-induced cell death was reversed by the pan-caspase inhibitor Z-VAD-FMK, by the autophagy inhibitor 3-MA and by the knockdown of LC3B using a shRNA (shLC3B), suggesting that autophagy promoted CPZ-induced apoptosis. Finally, CPZ significantly suppressed tumor growth in both a zebrafish oral cancer xenotransplantation model and in a murine model of 4-nitroquinoline-1-oxide (4NQO)-induced oral cancer. Overall, this evidence demonstrated that CPZ is a novel promising strategy for the treatment of oral cancer.

Autophagy modulation as a potential targeted cancer therapy: From drug repurposing to new drug development

Autophagy is an evolutionarily conserved signaling pathway to deliver dysfunctional proteins or organelles into lysosomes for degradation and recycling, which is an important pathway for normal homeostasis. Autophagy dysfunction can lead to various diseases, particularly cancer. Autophagy not only plays a role in tumor suppression, but it also serves as a tumor promoter in cancer malignancy. In this review, we summarize the involvement of autophagy-related (ATG) proteins in autophagy signaling and the role of autophagy in cancer progression. The effectiveness of US Food and Drug Administration-approved drugs in regulating autophagic flux and suppressing cancer cells is also discussed. Moreover, since clinically available drugs do not specifically target ATG proteins, there is little doubt that their cancer suppression function is autophagy dependent. Therefore, this review also discusses several inhibitors against ATG proteins, such as ULK1/2, ATG4, and VPS34 to suppress cancer cells. Autophagy modulators can be either used alone or combined with chemotherapy or radiation therapy to enhance the efficacy of current treatments for certain types of cancer. This review summarizes current autophagy modulation used as a potential strategy for targeted cancer therapy.

Ovarian hormones-autophagy-immunity axis in menstruation and endometriosis

Menstruation occurs in few species and involves a cyclic process of proliferation, breakdown and regeneration under the control of ovarian hormones. Knowledge of normal endometrial physiology, as it pertains to the regulation of menstruation, is essential to understand disorders of menstruation. Accumulating evidence indicates that autophagy in the endometrium, under the regulation of ovarian hormones, can result in the infiltration of immune cells, which plays an indispensable role in the endometrium shedding, tissue repair and prevention of infections during menstruation. In addition, abnormal autophagy levels, together with resulting dysregulated immune system function, are associated with the pathogenesis and progression of endometriosis. Considering its potential value of autophagy as a target for the treatment of menstrual-related and endometrium-related disorders, we review the activity and function of autophagy during menstrual cycles. The role of the estrogen/progesterone-autophagy-immunity axis in endometriosis are also discussed.

The interplay of ROS and the PI3K/Akt pathway in autophagy regulation

Autophagy causes the breakdown of damaged proteins and organelles to their constituent components. The phosphatidylinositol 3-kinase (PI3K) pathway played an important role in regulating the autophagic response of cells in response to changing reactive oxygen species (ROS) levels. The PI3K α catalytic subunit inhibits autophagy, while its β catalytic subunit promotes autophagy in response to changes in ROS levels. The downstream Akt protein acts against autophagy initiation in response to increases in ROS levels under nutrient-rich conditions. Akt acts by activating a mechanistic target of the rapamycin complex 1 (mTORC1) and by arresting autophagic gene expression. The AMP-activated protein kinase (AMPK) protein counteracts the Akt actions. mTORC1 and mTORC2 inhibit autophagy under moderate ROS levels, but under high ROS levels, mTORC2 can promote cellular senescence via autophagy. Phosphatase and tensin homolog (PTEN) protein are the negative regulators of the PI3K pathway, and it has proautophagic activities. Studies conducted on cells treated with flavonoids and ionizing radiation showed that the moderate increase in ROS levels in the flavonoid-treated groups corresponded with higher PTEN levels and lowered Akt levels leading to a higher occurrence of autophagy. In contrast, higher ROS levels evoked by ionizing radiation caused a lowering of the incidence of autophagy.

Directed evolution of cyclic peptides for inhibition of autophagy

In recent decades it has become increasingly clear that induction of autophagy plays an important role in the development of treatment resistance and dormancy in many cancer types. Unfortunately, chloroquine (CQ) and hydroxychloroquine (HCQ), two autophagy inhibitors in clinical trials, suffer from poor pharmacokinetics and high toxicity at therapeutic dosages. This has prompted intense interest in the development of targeted autophagy inhibitors to re-sensitize disease to treatment with minimal impact on normal tissue. We utilized Scanning Unnatural Protease Resistant (SUPR) mRNA display to develop macrocyclic peptides targeting the autophagy protein LC3. The resulting peptides bound LC3A and LC3B-two essential components of the autophagosome maturation machinery-with mid-nanomolar affinities and disrupted protein-protein interactions (PPIs) between LC3 and its binding partners in vitro. The most promising LC3-binding SUPR peptide accessed the cytosol at low micromolar concentrations as measured by chloroalkane penetration assay (CAPA) and inhibited starvation-mediated GFP-LC3 puncta formation in a concentration-dependent manner. LC3-binding SUPR peptides re-sensitized platinum-resistant ovarian cancer cells to cisplatin treatment and triggered accumulation of the adapter protein p62 suggesting decreased autophagic flux through successful disruption of LC3 PPIs in cell culture. In mouse models of metastatic ovarian cancer, treatment with LC3-binding SUPR peptides and carboplatin resulted in almost complete inhibition of tumor growth after four weeks of treatment. These results indicate that SUPR peptide mRNA display can be used to develop cell-penetrating macrocyclic peptides that target and disrupt the autophagic machinery in vitro and in vivo.

Autophagy and salivary gland cancer: A putative target for salivary gland tumors

Salivary gland carcinomas are a group of heterogeneous tumors of different histological subtypes, presenting relatively low incidence but the entire variable of types. Although novel treatment options for salivary gland carcinomas patients' outcomes have improved, the treatment of this type of cancer is still not standardized. In addition, a significant number of patients, with a lack of optimal treatment strategies, have reduced survival. In the last two decades, a plethora of evidence pointed to the importance of autophagy, an essential catabolic process of cytoplasmatic component digestion, in cancer. In vitro and in vivo studies highlight the importance of autophagy in salivary gland carcinomas development as a tumor suppressor or promoter mechanism. Despite the potential of autophagy in salivary gland carcinomas development, no therapies are currently available that specifically focus on autophagy modulation in salivary gland carcinomas. In this review, we summarize current knowledge and clinical trials in regard to the interplay between autophagy and the development of salivary gland carcinomas. Autophagy manipulation may be a putative therapeutic strategy for salivary gland carcinomas patients.

The role of long non-coding RNAs in mediating chemoresistance by modulating autophagy in cancer

Cancer is a complex process in which protein-coding and non-coding genes play essential roles. Long noncoding RNAs (lncRNAs), as a subclass of noncoding genes, are implicated in various cancer processes including growth, proliferation, metastasis, and angiogenesis. Due to presence in body fluids such as blood and urine, lncRNAs have become novel biomarkers in cancer detection, diagnosis, progression, and therapy response. Remarkably, increasing evidence has verified that lncRNAs play essential roles in chemoresistance by targeting different signalling pathways. Autophagy, a highly conserved process in response to environmental stresses such as starvation and hypoxia, plays a paradoxical role in inducing resistance or sensitivity to chemotherapy agents. In this regard, we reviewed chemoresistance, the role of lncRNAs in cancer, and the role of lncRNAs in chemoresistance by modulating autophagy.

Galectin-3 Expression in Pancreatic Cell Lines Under Distinct Autophagy-Inducing Stimulus

Hypoxia and nutrient deprivation are responsible for inducing malignant behavior in neoplastic cells. In these conditions, metabolic stress leads the cells to enhance their autophagic flux and to activate key molecules for homeostasis maintenance. Galectin-3 (Gal-3) is upregulated in pancreatic cancer and it is activated under the hypoxic atmosphere. We aimed to analyze the most effective autophagic-inducing conditions in pancreatic ductal adenocarcinoma cells and the effect exerted under these conditions in association with hypoxia on the Gal-3 expression. Gal-3 and the microtubule-associated protein light chain 3 beta (LC3) were accessed through western blot and immunofluorescence. Degradative vacuole quantification was analyzed by transmission electronic microscopy, and inhibition of Gal-3 was performed using siRNA. According to the analyses, the most effective conditions in the inducement of autophagy for PANC-1 and MIA PaCa-2 cells were nutritional deprivation and complete amino acid/glucose deprivation, respectively. PANC-1 cells presented higher Gal-3 when they were submitted to 24 h of nutritional deprivation alone and simultaneously nutritional and oxygen deprivation. Inhibition of Gal-3 causes a decrease of LC3 levels in all experimental conditions. These results confirm that Gal-3 is modulated by microenvironment factors and the possibility of Gal-3 participating in an adaptive response from PDAC cells to extreme conditions.

Western influenced lifestyle and Kv2.1 association as predicted biomarkers for Tunisian colorectal cancer

BACKGROUND

Colorectal cancer (CRC) is the third most diagnosed malignancy worldwide. The global burden is expected to increase along with ongoing westernized behaviors and lifestyle. The etiology of CRC remains elusive and most likely combines environmental and genetic factors. The Kv2.1 potassium channel encoded by KCNB1 plays a collection of roles in malignancy of cancer and may be a key factor of CRC susceptibility. Our study provides baseline association between Tunisian CRC and interactions between KCNB1 variants and lifestyle factors.

METHODS

A case-control study involving 300 CRC patients, and 300 controls was conducted Patients were carefully phenotyped and followed till the end of study. KCNB1 genotyping was confirmed by Sanger sequencing. Bivariate and multivariable logistic regression analyses were used to assess the clinical status, lifestyle and study polymorphisms association with CRC.

RESULTS

We noted significant gender association with CRC occurrence. Moreover, CRC risk increases with high meat and fat consumption, alcohol use and physical activity (PA). Carriage of rs1051296 A/G and both rs11468831 ins/del and del/del genotypes (p < 0.001) were significantly associated with CRC risk. Analysis according to gender reveals correlation of rs1051295 A/G, rs11468831 non ins/ins (p = 0.01) with CRC susceptibility regardless of patients' gender while rs3331 T/C (p = 0.012) was associated with females. Stratification study according to malignancy site; Rectal Cancer (RC) and Colon Cancer (CC), reveals increasing RC risk by gender and high meat and fat consumption, alcohol use and PA. However, additional association with high brine consumption was noted for CC. The rs1051295 A/G (p = 0.01) was associated with RC risk. Increased CC risk was associated with carriage of rs1051295 A/G, rs11168831 (del/del) and (ins/del) genotypes.

CONCLUSION

The risk of CRC increases with modifiable factors by Western influences on Tunisian lifestyle such as alcohol use, high fat consumption and possibly inadequate intake of vegetables. In addition, KCNB1 polymorphisms also markedly influence CRC susceptibility. Our study establishes key elements of a baseline characterization of clinical state, Western influenced lifestyle and KCNB1 variants associated with Tunisian CRC.

Oncolytic Reovirus (pelareorep) Induces Autophagy in KRAS-mutated Colorectal Cancer

PURPOSE

To explore the effects of pelareorep on autophagy in multiple models of colorectal cancer, including patient-derived peripheral blood mononuclear cells (PBMCs).

EXPERIMENTAL DESIGN

HCT116 [KRAS mutant (mut)] and Hke3 [KRAS wild-type (WT)] cells were treated with pelareorep (multiplicity of infection, 5) and harvested at 6 and 9 hours. LC3 A/B expression was determined by immunofluorescence and flow cytometry; five autophagic proteins were analyzed by Western blotting. The expression of 88 autophagy genes was determined by qRT-PCR. Syngeneic mouse models, CT26/Balb-C (KRAS mut) and MC38/C57B6 (KRAS WT), were developed and treated with pelareorep (10 × 10⁶ plaque-forming unit/day) intraperitoneally. Protein and RNA were extracted from harvested tumor tissues. PBMCs from five experimental and three control patients were sampled at 0 (pre) and 48 hours, and on days 8 and 15. The gene expression normalized to "pre" was determined using 2^{-ΔΔC _t} method.

RESULTS

Pelareorep induced significant upregulation of LC3 A/B in HCT116 as compared with Hke3 cells by immunofluorescence (3.24 × and 8.67 ×), flow cytometry (2.37 × and 2.58 ×), and autophagosome formation (2.02 × and 1.57 ×), at 6 and 9 hours, respectively; all P < 0.05. Western blot analysis showed an increase in LC3 A/B (2.38 × and 6.82 ×) and Beclin1 (1.17 × and 1.24 ×) at 6 and 9 hours, ATG5 (2.4 ×) and P-62 (1.52 ×) at 6 hours, and VPS-34 (1.39 ×) at 9 hours (all P < 0.05). Induction of 13 transcripts in cell lines (>4 ×; 6 and 9 hours; P < 0.05), 12 transcripts in CT26 (qRT-PCR), and 14 transcripts in human PBMCs (P < 0.05) was observed. LC3 A/B, RICTOR, and RASD1 expression was upregulated in all three model systems.

CONCLUSIONS

Pelareorep hijacks host autophagic machinery in KRAS-mut conditions to augment its propagation and preferential oncolysis of the cancer cells.

Recent developments in autophagy-targeted therapies in cancer

Autophagy plays a crucial role in cellular development and differentiation as well as in the maintenance of homeostasis in healthy cells. Autophagy is well documented in neurodegenerative disorders, aging, and infectious diseases. However, recognizing its significance in cancer has always been challenging due to its tumor-promoting and suppressive attributes. Various modulators targeting key components of autophagy machinery directly or indirectly have been developed over the years, and have shown promising results in preclinical models. Some of these compounds are even being tested in clinical trials for safety and efficacy. A detailed review of strategies used to target autophagy in cancer is presented including our opinion on developing better therapies and outstanding issues.

Costunolide and dehydrocostuslactone from Saussurea lappa root inhibit autophagy in hepatocellular carcinoma cells

Autophagy is a catabolic process for degradation of intracellular components and plays an important role in the development and growth of cancer. Our preliminary screening confirmed that an extract from the root of Saussurea lappa remarkably suppressed the proliferation of HepG2 hepatocellular carcinoma cells and inhibited autophagy. In this study, we explored the effects of costunolide (CL) and dehydrocostuslactone (DCL), which are bioactive sesquiterpene lactones in this extract, on autophagy modulation in HepG2 cells. An analysis of autophagy-related proteins demonstrated that CL and DCL blocks the autophagy process that leads to the accumulation of microtubule-associated protein 1 light chain 3 (LC3) and SQSTM1/p62 (p62). LC3 turnover assays indicated that CL and DCL trigger autophagy inhibition by blocking the autophagic flux, thereby resulting in the accumulation of LC3-II and p62. These results are encouraging and warrant further study of CL and DCL for potential use as autophagy inhibiting agents for liver cancer therapy.

Regulation of autophagy by canonical and non-canonical ER stress responses

Cancer cells encounter numerous stresses that pose a threat to their survival. Tumor microenviroment stresses that perturb protein homeostasis can produce endoplasmic reticulum (ER) stress, which can be counterbalanced by triggering the unfolded protein response (UPR) which is considered the canonical ER stress response. The UPR is characterized by three major proteins that lead to specific changes in transcriptional and translational programs in stressed cells. Activation of the UPR can induce apoptosis, but also can induce cytoprotective programs such as autophagy. There is increasing appreciation for the role that UPR-induced autophagy plays in supporting tumorigenesis and cancer therapy resistance. More recently several new pathways that connect cell stresses, components of the UPR and autophagy have been reported, which together can be viewed as non-canonical ER stress responses. Here we review recent findings on the molecular mechanisms by which canonical and non-canonical ER stress responses can activate cytoprotective autophagy and contribute to tumor growth and therapy resistance. Autophagy has been identified as a druggable pathway, however the components of autophagy (ATG genes) have proven difficult to drug. It may be the case that targeting the UPR or non-canonical ER stress programs can more effectively block cytoprotective autophagy to enhance cancer therapy. A deeper understanding of these pathways could provide new therapeutic targets in cancer.

The role of FOXOs and autophagy in cancer and metastasis-Implications in therapeutic development

Autophagy is a highly conserved intracellular degradation process that plays a crucial role in cell survival and stress reactions as well as in cancer development and metastasis. Autophagy process involves several steps including sequestration, fusion of autophagosomes with lysosomes and degradation. Forkhead box O (FOXO) transcription factors regulate the expression of genes involved in cellular metabolic activity and signaling pathways of cancer growth and metastasis. Recent evidence suggests that FOXO proteins are also involved in autophagy regulation. The relationship among FOXOs, autophagy, and cancer has been drawing attention of many who work in the field. This study summarizes the role of FOXO proteins and autophagy in cancer growth and metastasis and analyzes their potential roles in cancer disease management.

The Double-Edge Sword of Autophagy in Cancer: From Tumor Suppression to Pro-tumor Activity

During tumorigenesis, cancer cells are exposed to a wide variety of intrinsic and extrinsic stresses that challenge homeostasis and growth. Cancer cells display activation of distinct mechanisms for adaptation and growth even in the presence of stress. Autophagy is a catabolic mechanism that aides in the degradation of damaged intracellular material and metabolite recycling. This activity helps meet metabolic needs during nutrient deprivation, genotoxic stress, growth factor withdrawal and hypoxia. However, autophagy plays a paradoxical role in tumorigenesis, depending on the stage of tumor development. Early in tumorigenesis, autophagy is a tumor suppressor via degradation of potentially oncogenic molecules. However, in advanced stages, autophagy promotes the survival of tumor cells by ameliorating stress in the microenvironment. These roles of autophagy are intricate due to their interconnection with other distinct cellular pathways. In this review, we present a broad view of the participation of autophagy in distinct phases of tumor development. Moreover, autophagy participation in important cellular processes such as cell death, metabolic reprogramming, metastasis, immune evasion and treatment resistance that all contribute to tumor development, is reviewed. Finally, the contribution of the hypoxic and nutrient deficient tumor microenvironment in regulation of autophagy and these hallmarks for the development of more aggressive tumors is discussed.

The Mechanical Autophagy as a Part of Cellular Immunity; Facts and Features in Treating the Medical Disorders

Autophagy is a cellular housekeeping process that incorporates lysosomal-degradation to maintain cell survival and energy sources. In recent decades, the role of autophagy has implicated in the initiation and development of many diseases that affect humanity. Among these diseases are autoimmune diseases and neurodegenerative diseases, which connected with the lacking autophagy. Other diseases are connected with the increasing levels of autophagy such as cancers and infectious diseases. Therefore, controlling autophagy with sufficient regulators could represent an effective strategy to overcome such diseases. Interestingly, targeting autophagy can also provide a sufficient method to combat the current epidemic caused by the ongoing coronavirus. In this review, we aim to highlight the physiological function of the autophagic process to understand the circumstances surrounding its role in the cellular immunity associated with the development of human diseases.

Contrast effects of autophagy in the treatment of bladder cancer

Bladder cancer is a disease that negatively affects patients' quality of life, but treatment options have remained unchanged for a long time. Although promising results have been achieved with current bladder cancer treatments, cancer recurrence, progression, and therapy resistance are the most severe problems preventing the efficiency of bladder cancer treatments. Autophagy refers to an evolutionarily conserved catabolic process in which proteins, damaged organelles, and cytoplasmic components are degraded by lysosomal enzymes. Autophagy regulates the therapeutic response to the chemotherapy drugs, thus determining the effect of therapy on cancer cells. Autophagy is a stress-induced cell survival mechanism and its excessive stimulation can cause resistance of tumor cells to therapeutic agents. Depending on the conditions, an increase in autophagy may cause treatment resistance or autophagic cell death, and it is related to important anti-cancer mechanisms, such as apoptosis. Therefore, understanding the roles of autophagy under different conditions is important for designing effective anti-cancer agents. The dual role of autophagy in cancer has attracted considerable attention in respect of bladder cancer treatment. In this review, we summarize the basic characteristics of autophagy, including its mechanisms, regulation, and functions, and we present examples from current studies concerning the dual role of autophagy in bladder cancer progression and therapy.

Melatonin and urological cancers: a new therapeutic approach

Urological cancers are responsible for thousands of cancer-related deaths around the world. Despite all developments in therapeutic approaches for cancer therapy, the absence of efficient treatments is a critical and vital problematic issue for physicians and researchers. Furthermore, routine medical therapies contribute to several undesirable adverse events for patients, reducing life quality and survival time. Therefore, many attempts are needed to explore potent alternative or complementary treatments for great outcomes. Melatonin has multiple beneficial potential effects, including anticancer properties. Melatonin in combination with chemoradiation therapy or even alone could suppress urological cancers through affecting essential cellular pathways. This review discusses current evidence reporting the beneficial effect of melatonin in urological malignancies, including prostate cancer, bladder cancer, and renal cancer.

The Multifunctional Protein p62 and Its Mechanistic Roles in Cancers

The multifunctional signaling hub p62 is well recognized as a ubiquitin sensor and a selective autophagy receptor. As a ubiquitin sensor, p62 promotes NFκB activation by facilitating TRAF6 ubiquitination and aggregation. As a selective autophagy receptor, p62 sorts ubiquitinated substrates including p62 itself for lysosome-mediated degradation. p62 plays crucial roles in myriad cellular processes including DNA damage response, aging/senescence, infection and immunity, chronic inflammation, and cancerogenesis, dependent on or independent of autophagy. Targeting p62-mediated autophagy may represent a promising strategy for clinical interventions of different cancers. In this review, we summarize the transcriptional and post-translational regulation of p62, and its mechanistic roles in cancers, with the emphasis on its roles in regulation of DNA damage response and its connection to the cGAS-STING-mediated antitumor immune response, which is promising for cancer vaccine design.

Autophagy as a decisive process for cell death

Autophagy is an intracellular catabolic pathway in which cellular constituents are engulfed by autophagosomes and degraded upon autophagosome fusion with lysosomes. Autophagy serves as a major cytoprotective process by maintaining cellular homeostasis and recycling cytoplasmic contents. However, emerging evidence suggests that autophagy is a primary mechanism of cell death (autophagic cell death, ACD) and implicates ACD in several aspects of mammalian physiology, including tumor suppression and psychological disorders. However, little is known about the physiological roles and molecular mechanisms of ACD. In this review, we document examples of ACD and discuss recent progress in our understanding of its molecular mechanisms.

KCNB1 gene polymorphisms and related indel as predictor biomarkers of treatment response for colorectal cancer - toward a personalized medicine

The KCNB1 gene variants were differentially associated with cancers. However, their association with colorectal cancer has not yet been explored. We investigated the contribution of the KCNB1 gene variants rs3331, rs1051295, and indel (insertion/deletion) rs11468831 Polymorphism as predictors of the treatment response in colorectal cancer patients. A retrospective study, which involved 291 Tunisian colorectal cancer patients (aged 60.0 ± 13.1 years), who were stratified into responder and non-responder groups, according to TNM stages and their responsiveness to chemotherapy based on fluorouracil. KCNB1 genotyping was performed with amplification-refractory mutation system-polymerase chain reaction, and was confirmed by Sanger sequencing. Sex-specific response was found and colorectal cancer females are less likely to achieve a positive response during the chemotherapy strategy, compared to males. Weight and body mass index, tumor size, and tumor localization are considered as predictive factors to treatment responsiveness. Carriage of rs11468831 Ins allele was significantly associated with successful therapy achievement (p adjusted < 0.001). Stratification of colorectal cancer patients' response according to tumor localization and TNM stages reveals negative association of rs3331 Major allele to treatment response among the patients with advanced cancer stages (subgroup G2). The presence of rs3331 (homozygous minor) C/C genotype was positively associated with decline in carcino-embryonic antigen (p = 0.043) and CA19-9 (p = 0.014) serum levels. On the other hand, the presence of rs1051295 (homozygous minor) A/A genotype was correlated with marked decline in CA19-9 serum levels. KCNB1 haplotype did not reveal any association between haplotypes and treatment response. The results obtained suggest that gender-specific strategies for screening treatment and prevention protocols as well as KCNB1 variants may constitute an effective model for ongoing personalization medicine.

The role of autophagy in resistance to targeted therapies

Autophagy is a self-degradative cellular process, involved in stress response such as starvation, hypoxia, and oxidative stress. This mechanism balances macro-molecule recycling to regulate cell homeostasis. In cancer, autophagy play a role in the development and progression, while several studies describe it as one of the key processes in drug resistance. In the last years, in addition to standard anti-cancer treatments such as chemotherapies and irradiation, targeted therapy became one of the most adopted strategies in clinical practices, mainly due to high specificity and reduced side effects. However, similar to standard treatments, drug resistance is the main challenge in most patients. Here, we summarize recent studies that investigated the role of autophagy in drug resistance after targeted therapy in different types of cancers. We highlight positive results and limitations of pre-clinical and clinical studies in which autophagy inhibitors are used in combination with targeted therapies.

Identification and validation of an individualized autophagy-clinical prognostic index in gastric cancer patients

Background

The purpose of this study is to perform bioinformatics analysis of autophagy-related genes in gastric cancer, and to construct a multi-gene joint signature for predicting the prognosis of gastric cancer.

Methods

GO and KEGG analysis were applied for differentially expressed autophagy-related genes in gastric cancer, and PPI network was constructed in Cytoscape software. In order to optimize the prognosis evaluation system of gastric cancer, we established a prognosis model integrating autophagy-related genes. We used single factor Cox proportional risk regression analysis to screen genes related to prognosis from 204 autophagy-related genes in The Atlas Cancer Genome (TCGA) gastric cancer cohort. Then, the generated genes were applied to the Least Absolute Shrinkage and Selection Operator (LASSO). Finally, the selected genes were further included in the multivariate Cox proportional hazard regression analysis to establish the prognosis model. According to the median risk score, patients were divided into high-risk group and low-risk group, and survival analysis was conducted to evaluate the prognostic value of risk score. Finally, by combining clinic-pathological features and prognostic gene signatures, a nomogram was established to predict individual survival probability.

Results

GO analysis showed that the 28 differently expressed autophagy-related genes was enriched in cell growth, neuron death, and regulation of cell growth. KEGG analysis showed that the 28 differently expressed autophagy-related genes were related to platinum drug resistance, apoptosis and p53 signaling pathway. The risk score was constructed based on 4 genes (GRID2, ATG4D,GABARAPL2, CXCR4), and gastric cancer patients were significantly divided into high-risk and low-risk groups according to overall survival. In multivariate Cox regression analysis, risk score was still an independent prognostic factor (HR = 1.922, 95% CI = 1.573–2.349, P < 0.001). Cumulative curve showed that the survival time of patients with low-risk score was significantly longer than that of patients with high-risk score (P < 0.001). The external data GSE62254 proved that nomograph had a great ability to evaluate the prognosis of individual gastric cancer patients.

Conclusions

This study provides a potential prognostic marker for predicting the prognosis of GC patients and the molecular biology of GC autophagy.

Cepharanthine hydrochloride induces mitophagy targeting GPR30 in hepatocellular carcinoma (HCC)

Objectives: Cepharanthine exhibits a wide range of therapeutic effects against numerous cancers by virtue of its pleiotropic mechanisms. However, cepharanthine monotherapy has insufficient drug efficacy for cancers in animal models and clinical trials. The mechanism of its limited efficacy is unknown.Methods: We investigated the possible mechanism for the limited drug efficacy of cepharanthine in cancer therapy using both hepatocellular carcinoma (HCC) primary cells and cell lines, in vitro and in mouse xenograft models.Results: We found that cepharanthine hydrochloride (CH), a semi-synthetic derivative of cepharanthine, induced mitophagy independent of mTOR signaling, and played an AMPK-dependent protective role in the cell fate of HCC in vitro and in vivo. Mechanistically, we demonstrated that CH may bind to GPR30 receptor to activate the subsequent signal cascade involving mitochondrial fission, thus facilitating mitophagy. Therefore, we proposed a new therapeutic regimen for HCC involving CH combined with an autophagy inhibitor. This regimen exhibited remarkable anti-cancer effects in HCC xenograft mouse model.Conclusion: These results identify CH as a new mitophagy inducer targeting GPR30 receptor. The combination therapy of CH and an autophagy inhibitor may become a novel strategy for enhancing the anti-tumor potential of cepharanthine in HCC.

Therapeutic Potential of Autophagy Modulation in Cholangiocarcinoma

Autophagy is a multistep catabolic process through which misfolded, aggregated or mutated proteins and damaged organelles are internalized in membrane vesicles called autophagosomes and ultimately fused to lysosomes for degradation of sequestered components. The multistep nature of the process offers multiple regulation points prone to be deregulated and cause different human diseases but also offers multiple targetable points for designing therapeutic strategies. Cancer cells have evolved to use autophagy as an adaptive mechanism to survive under extremely stressful conditions within the tumor microenvironment, but also to increase invasiveness and resistance to anticancer drugs such as chemotherapy. This review collects clinical evidence of autophagy deregulation during cholangiocarcinogenesis together with preclinical reports evaluating compounds that modulate autophagy to induce cholangiocarcinoma (CCA) cell death. Altogether, experimental data suggest an impairment of autophagy during initial steps of CCA development and increased expression of autophagy markers on established tumors and in invasive phenotypes. Preclinical efficacy of autophagy modulators promoting CCA cell death, reducing invasiveness capacity and resensitizing CCA cells to chemotherapy open novel therapeutic avenues to design more specific and efficient strategies to treat this aggressive cancer.