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Autophagy (self-eating) is a conserved cellular degradation process that plays important roles in maintaining homeostasis and preventing nutritional, metabolic, and infection-mediated stresses. Autophagy dysfunction can have various pathological consequences, including tumor progression, pathogen hyper-virulence, and neurodegeneration. This review describes the mechanisms of autophagy and its associations with other cell death mechanisms, including apoptosis, necrosis, necroptosis, and autosis. Autophagy has both positive and negative roles in infection, cancer, neural development, metabolism, cardiovascular health, immunity, and iron homeostasis. Genetic defects in autophagy can have pathological consequences, such as static childhood encephalopathy with neurodegeneration in adulthood, Crohn’s disease, hereditary spastic paraparesis, Danon disease, X-linked myopathy with excessive autophagy, and sporadic inclusion body myositis. Further studies on the process of autophagy in different microbial infections could help to design and develop novel therapeutic strategies against important pathogenic microbes. This review on the progress and prospects of autophagy research describes various activators and suppressors, which could be used to design novel intervention strategies against numerous diseases and develop therapeutic drugs to protect human and animal health.

Expression profiles revealed miR-1299 downregulation concomitant with arginase-2 ( ARG2) upregulation in hyperpigmented skin of melasma patients. Opposite regulation of tyrosinase and PMEL17 by miR-1299 and inverse relationship between miR-1299 and ARG2 expression denoted a role of miR-1299 in pigmentation with ARG2 as a miR-1299 target. ARG2 overexpression or knock-down in keratinocytes, the main source of ARG2 in epidermis, positively regulated tyrosinase and PMEL17 protein levels, but not mRNA levels or melanosome transfer. ARG2 overexpression in keratinocytes reduced autophagy equivalent to 3- MA, an autophagy inhibitor which also increased tyrosinase and PMEL17 protein levels, whereas ARG2 knock-down induced opposite results. Autophagy inducer rapamycin reduced ARG2-increased tyrosinase and PMEL17 protein levels. Also, autophagy was reduced in late passage-induced senescent keratinocytes showing ARG2 upregulation. ARG2, but not 3- MA, stimulated keratinocyte senescence. These results suggest that ARG2 reduces autophagy in keratinocytes by stimulating cellular senescence, resulting in skin pigmentation by reducing degradation of transferred melanosomes. [ABSTRACT FROM AUTHOR]

Drug nanocarriers that have long been expected to revolutionize cancer therapy have yet to achieve the significant clinical success. Therefore, it remains controversial to pursue a complex drug nanocarrier that lacks clinical relevance. Herein, we developed an easily-synthesized anti-tumor drug that actively seeks the acidic tumor microenvironment while ignoring the normal tissue without the aid of additional carriers. This called “carrier-free” drug (CFD) is capable of switching its morphology from the unstructured solution to the spherical structure in response to tumor acidity. CFDs were the water-soluble zwitterionic unimers to prevent the non-specific distribution in the circulation, whereas they spontaneously formed into the particles tending to accumulation in tumor. CFD overloading in tumor cells caused the lysosomal dysfunction and autophagy blockage, thereby triggered the cell death. All the in vitro and in vivo data demonstrated the tumor-acidity-selective cytotoxicity of CFD. This facile strategy to create a self-delivering anticancer drug may cast a new light on the development of cancer therapy. [ABSTRACT FROM AUTHOR]

Non-steroidal anti-inflammatory drug (NSAID)-associated endoplasmic reticulum (ER) stress (a cyclooxygenase-2-independent mechanism) and consequent autophagic cell death are responsible for NSAID-associated gastric damage. Therefore, alleviating cytotoxicity executed via ER stress and autophagy can be a strategy to prevent NSAID-associated gastric damage. Here, we explored whether genetic or pharmacologic inhibition of autophagy can mitigate NSAID-associated gastric damage in in vitro and in vivo models. To examine the effects of genetic inhibition of NSAID-associated autophagy, we administered indomethacin to RGM1 gastric mucosal cells transfected with shPERK, siLC3B, or shATG5 and microtubule-associated protein light chain 3B knock-out (LC3B) mice. 3-Methyladenine (3-MA) or chloroquine (CQ) was used for pharmacologic inhibition of autophagy in both models. Indomethacin administration increased the expression of ER stress proteins including GRP78, ATF6, and CHOP. Indomethacin provoked the appearance of autophagic vesicles with the increased expression of ATG5 and LC3B-II. Genetic ablation of various ER stress genes significantly attenuated indomethacin-induced autophagy and apoptosis ( p < 0.01), whereas knock-down of either ATG5 or LC3B significantly reduced indomethacin-induced cytotoxicity ( p < 0.01). Testing each of the genes implicated in ER stress and autophagy showed that indomethacin leads to gastric cell apoptosis through autophagy induction consequent to ER stress. Pharmacological inhibition of autophagy with either 3-MA or CQ in rats or genetic ablation of LC3B in mice all had a significant rescuing effect against indomethacin-associated gastric damage ( p < 0.01) and a decrease in molecular markers of autophagic and apoptotic gastric cells. In conclusion, preemptive autophagy inhibition can be a potential strategy to mitigate NSAID-associated gastric damage. Key messages: [ABSTRACT FROM AUTHOR]

Pancreatic ductal adenocarcinoma (PDAC) is one of the few cancer types where the 5-year survival rate shows no improvement. Despite conflicting evidence, the majority of data points to an essential role for autophagy in PDAC growth and survival, in particular constitutively activated autophagy, can provide crucial fuel to PDAC tumor cells in their nutrient-deprived environment. Autophagy, which is required for cell homeostasis, can both suppress and promote tumorigenesis and tumor survival in a context-dependent manner. Protein by protein, the mystery of how PDAC abuses the cell's homeostasis system for its malignant growth has recently begun to be unraveled. In this review, we focus on how autophagy is responsible for growth and development of PDAC tumors and where autophagy and the mechanisms controlling it fit into PDAC metabolism. Understanding the range of pathways controlling autophagy and their interplay in PDAC could open the way for new therapeutic avenues. [ABSTRACT FROM AUTHOR]

Drug resistance in cancer chemotherapy is a major confounding factor affecting the effectiveness of chemotherapeutic agents, thereby leading to poor clinical outcomes. Most chemotherapeutic drugs can induce protective autophagy and increase the resistance of tumors to chemotherapeutic drugs and reduce effective drug delivery to tumor cells. In this study, a tri-drug nanocomposite (NP) delivery system was devised using carboxymethyl β-dextran (CMD) and protamine sulfate (PS), two natural materials with good bio-compatibility. They were designed to carry the chemotherapeutic drug docetaxel (DTX), the autophagy inhibitor chloroquine (CQ), and Atg5 siRNA to cancer cells. The CQ + DTX + Atg5 siRNA NPs was driven by electrostatic interaction and self-assembly methods. The breast cancer cell line MDA-MB-231 was used for both cell culture and establishing mouse xenograft model. Our findings demonstrated that CQ and Atg5 siRNA encapsulated in NPs could enhance the sensitivity of tumor cells to DTX. The NPs exhibited remarkable considerable therapeutic effects for treating triple-negative breast cancer (TNBC) and good biosafety. Therefore, we established a novel multifunctional nanoplatform based on CMD and PS that enhances chemotherapeutic drug sensitivity through an autophagy inhibition strategy, providing new opportunities to overcome conventional drug resistance and enhance therapeutic efficiency against TNBC. • Trio-drug co-delivery nanocomposites are designed to overcome drug resistance or side effects caused by conventional treatments for breast cancer. • The trio-drug co-delivery nanocomposites boost the chemotherapeutic drug sensitivity and achieve synergistic treatment goals through gene therapy and autophagy inhibition strategy. • The novel-designed nanoplatform has the potential to be utilized for treating stubborn triple-negative breast cancer. [ABSTRACT FROM AUTHOR]

The ultrasound-triggered sonodynamic therapy (SDT) with high tissue penetration, high spatiotemporal selectivity, and non-invasive advantages represents an emerging approach to eradicating deep-seated solid tumors. However, the outcomes of SDT are typically hampered by the inefficient generation of reactive oxygen species (ROS) and the activation of protective autophagy. Here, to improve the antitumor efficiency of SDT on colorectal cancer, we rationally design a cascade nanoreactor by incorporating sonosensitizer Ce6 and autophagy inhibitor chloroquine into the homologous tumor cell membrane-modified hollow polydopamine nanocarrier that is pre-doped with platinum nanozymes (designated as CCP@HP@M). The cascade reactions of CCP@HP@M are evidenced by the results that HP exhibits superoxide dismutase-mimicking activity that converts O 2 ·− to O 2 and H 2 O 2 , and platinum nanozymes further catalyze the excess H 2 O 2 to produce toxic ·OH and O 2. CCP@HP@M effectively accumulates in the tumor cells, resulting in a remarkably enhanced SDT efficiency for eliminating the tumor cells in vitro and in vivo. Under ultrasound irradiation, CCP@HP@M effectively alleviates the hypoxic condition, enhances ROS generation, and inhibits the protective autophagy pathway, which results in stimulating apoptosis and ferroptosis in vitro and in vivo. The RNA-seq analyses also confirmed apoptosis and ferroptosis pathways involved in the CCP@HP@M treatment. This cascade nanoreactor will provide a promising strategy for augmenting SDT eradication against tumors by modulation of ROS and autophagy. [Display omitted] • A cascade nanoreactor (SOD-CAT, SOD-POD) is constructed to enhance sonodynamic therapy by augmenting ROS production. • CCP@HP@M treatment improves sonodynamic therapy via ROS augment and autophagy blockage. • Under ultrasound irradiation, CCP@HP@M stimulates apoptosis and ferroptosis in vitro and in vivo. • The RNA-seq analyses confirm apoptosis and ferroptosis pathways involved in the CCP@HP@M treatment. [ABSTRACT FROM AUTHOR]

Anticancer immunotherapy is hampered by the poor tumor immunogenicity and immunosuppressive tumor microenvironment (TME). Herein, a liposome nanodrug co-encapsulating doxycycline hydrochloride (Doxy) and chlorin e6 (Ce6) to simultaneously induce autophagy inhibition and mitochondria dysfunction for potentiating tumor photo-immunotherapy is developed. Under near infrared laser irradiation, Ce6 generates cytotoxic reactive oxygen species (ROS) and elicits robust photodynamic therapy (PDT)-induced immunogenic cell death (ICD) for immunosuppressive TME remodeling. In addition, Doxy induced mitochondria dysfunction, which increases ROS generation and enhances PDT to exert more potent killing effect and more powerful ICD. Meanwhile, Doxy increases MHC-I expression on tumor cells surface by efficient autophagy inhibition, leading to more efficient antigen presentation and CTLs recognition to increase tumor immunogenicity. The nanodrugs elicit remarkable antitumor therapy by combining Ce6-mediated PDT and Doxy-induced autophagy inhibition and mitochondria dysfunction. The developed nanodrugs represent a highly efficient strategy for improving cancer immunotherapy., (© 2023 Wiley-VCH GmbH.)

• The biodegradable therapeutic FePi-PEG@DOX nanosheets were constructed. • These nanosheets can be degraded under the stimulation of tumor microenvironment. • The autophagy capacity of tumor cells was inhibited to cause damage accumulation. • Tumor elimination was achieved through enhanced apoptosis/ferroptosis pathway. Killing tumor cells through apoptosis and/or ferroptosis pathways has been extensively explored for tumor therapy. However, the therapeutic efficacy is always impaired by the autophagy-mediated self-repairing capacity of tumor cells. Herein, a novel autophagy inhibition-enhanced apoptosis/ferroptosis strategy was developed for synergistic tumor elimination, which was realized through the doxorubicin (DOX)-loaded ferric phosphate nanosheets. When located in tumor regions, these nanosheets can be specifically degraded under the stimulation of tumor microenvironment. The released DOX can not only damage DNA to induce cell apoptosis directly but also up-regulate intracellular hydrogen peroxide level. Free Fe2+ can be generated from Fe3+ through intracellular over-expressed glutathione-participated redox reaction, which can further react with hydrogen peroxide through the Fenton reaction to produce highly oxidative hydroxyl radicals. This redox process simultaneously breaks the antioxidant capacity of tumor cells through the depletion of glutathione and the inactivation of intracellular antioxidase glutathione peroxidase 4, promoting the generation and accumulation of lipid peroxidation to cause tumor ferroptosis. Especially, PO 4 3− disrupts the pH balance in lysosomes by forming conjugated acid anions to disable the self-repairing capacity of tumor cells, enhancing the antitumor therapeutic effect. This work offers a promising method with desirable biocompatibility for specific tumor elimination through autophagy inhibition-enhanced apoptosis/ferroptosis strategy. [ABSTRACT FROM AUTHOR]

[Display omitted] Ibrutinib (IBR) is an oral covalent inhibitor of Bruton's tyrosine kinase (BTK) that has been approved for the treatment of hematological malignancies. It was reported that IBR exhibited great therapeutic potential for glioma. However, the poor water solubility and high hepatic first-pass effect restrict its anti-glioma application. Meanwhile, IBR induces cytoprotective autophagy through Akt/mTOR signaling pathway, thus leading to a compromised antitumor effect. Herein, we aimed to develop a human serum albumin (HSA) based co-delivery system (IBR&HCQ HSA NPs) encapsulating IBR and hydroxychloroquine (HCQ). The bioavailability of IBR was largely improved, and enhanced sensitivity of glioma to IBR was achieved due to inhibition effect of HCQ on IBR-induced pro-survival autophagy. The physicochemical properties of IBR&HCQ HSA NPs were characterized to optimize the formulation. Biodistribution investigation revealed that HSA NPs (20 mg/kg, i.v.) dramatically increased the accumulation of IBR in glioma, which was 5.59 times higher than that of free IBR (100 mg/kg, i.g.). CCK-8 and apoptosis assays demonstrated that IBR&HCQ HSA NPs showed maximal cytotoxicity to C6 cells. In vivo studies indicated that the survival time was significantly prolonged in IBR&HCQ HSA NPs treated mice compared to those treated with IBR HSA NPs. Taken together, the HSA-based drug delivery system of IBR and HCQ opens a new avenue for efficient treatment of glioma. [ABSTRACT FROM AUTHOR]

Immunotherapy has been regarded as a breakthrough in cancer treatment and achieved great success. However, the poor response rate is still a formidable challenge of current immunotherapies, especially in solid tumors without sufficient infiltration of immune cells, also known as "cold tumor." SAR405 is a highly specific VPS34 inhibitor and has been suggested as a potential approach converting "cold tumor" into "hot tumor" by inhibiting autophagy. In this study, a tri-functional doxorubicin (DOX) plus SAR405 liposome system is established and further modified with a novel anti-PD-L1 peptide JY4 for targeted delivery (DOX-SAR-JY4 LIPO ). The data here demonstrate that in a lung cancer xenograft mouse model, by facilitating the tumoral enrichment of both SAR405 and DOX, DOX-SAR-JY4 LIPO effectively increases the infiltration of cytotoxic lymphocytes in the tumor by synergizing DOX-induced immunogenic cell death (ICD) and SAR405-mediated upregulation of chemokines including CCL5 and CXCL10. As results, DOX-SAR-JY4 LIPO significantly inhibits tumor growth, metastasis, and resurrection by re-educating immunosuppressive tumor microenvironment. In conclusion, this study not only proves the concept of inhibiting autophagy for better immune infiltration in the tumor but also presents a novel tri-functional liposomal system that overcomes the deficiencies of current therapies and holds great promise in cancer immunotherapy., (© 2023 Wiley-VCH GmbH.)

Cancer stem cells (CSCs) have garnered increasin g attention over the past decade, as they are believed to play a crucial role in tumor initiation, progression and metastasis, relapse and drug resistance. Therapeutic strategies which simultaneously exterminate both bulk tumor cells and the rare CSC subpopulation may produce striking response and result in long-term tumor remission. Accumulating evidence provides insight into the function of autophagy in maintenance, plasticity and survival of CSCs. The role of autophagy in the susceptibility of breast CSCs to chemotherapeutics was investigated in the present work, reduced ‘stemness’ and increased susceptibility to chemotherapy drugs (doxorubicin, DOX and docetaxel, DTXL) were observed after chloroquine (CQ)-mediated autophagy inhibition in sorted ALDH hi cells of breast cancer cell line MDA-MB-231. We further proved that nanoparticle-mediated autophagy inhibition promoted the efficacy of chemotherapeutics against ALDH hi MDA-MB-231 cells in vitro . Administration of drug delivery systems significantly prolonged the circulation half-life and augmented enrichment of two different drugs in tumor tissues and ALDH hi cells. More importantly, compared with single treatment, the combined delivery systems NP CQ /NP DOX and NP CQ/DOX (NP CQ /NP DTXL and NP CQ/DTXL ) showed most effective and persistent tumor growth inhibitory effect by eliminating bulk tumor cells as well as CSCs ( p < 0.01) in an MDA-MB-231 orthotopic tumor murine model. Therefore, our research provides new insights into the nanoparticle-facilitated combination of autophagy inhibition and chemotherapy for effective therapy of breast cancer. [ABSTRACT FROM AUTHOR]

Remote ischemic perconditioning (RIPerC) and ischemic postconditioning (IPOC) are well-acknowledged neuroprotective procedures during ischemic injury. The present study established a combined RIPerC and IPOC (RIPerC + IPOC) model in rats and studied how it would regulate the autophagy process and affect HMGB1 levels in a rat model of middle cerebral artery occlusion (MCAO). Rats with MCAO were treated with RIPerC by fastening and release of the left hind limb to achieve 4 cycles of 5 min remote ischemia reperfusion , 40 min prior to cerebral reperfusion, and then treated with IPOC by exposing the cerebral middle artery to 3 cycles of 30 s reperfusion/30 s occlusion at the onset of cerebral reperfusion. Infarction volumes, neurological deficits, and pathological changes were assessed 24 h after ischemia. The autophagy activator rapamycin (RAP) and the autophagy inhibitor 3-methyladenine (3-MA) were administrated for further mechanism. The expression and location of HMGB1 and the autophagy-related proteins like LC3, Beclin1, and P62 as well as plasma HMGB1 levels were measured. Our results suggested that RIPerC + IPOC attenuated plasma HMGB1 levels to intensify its neuroprotective effect against cerebral ischemic reperfusion injury via inhibiting the autophagy process. [ABSTRACT FROM AUTHOR]

Nowadays, the relationship between cancer blood coagulation is well established. Regarding biodiversity and bioprospection, the tick biology has become quite attractive natural source for coagulation inhibitors, since its saliva has a very rich variety of bioactive molecules. For instance, a Kunitz-type FXa inhibitor, named Amblyomin-X, was found through transcriptome of the salivary gland of the Amblyomma cajennense. tick. This TFPI-like inhibitor, after obtained as recombinant protein, has presented anticoagulant, antigionenic, and antitumor properties. Although its effects on blood coagulation could be relevant for antitumor effect, Amblyomin-X acts by non-hemostatic mechanisms, such as proteasome inhibition and autophagy inhibition. Notably, cytotoxicity was not observed on non-tumor cells treated with this protein, suggesting some selectivity for tumor cells. Considering the current efforts in order to develop effective anticancer therapies, the findings presented in this review strongly suggest Amblyomin-X as a promising novel antitumor drug candidate. [ABSTRACT FROM AUTHOR]

[Display omitted] • A multifunctional nanoplatform of BP-A-S@D has been prepared. • The issue of lysosomal drug sequestration mediated by nano-delivery systems is first proposed. • ClC-3 silencing inhibits lysosomal acidification to block the formation of lysosomes. • ClC-3 silencing inhibits lysosomal drug sequestration of DOX. • ClC-3 silencing inhibits protective autophagy to enhance chemo-photothermal therapy. Protective autophagy can be activated by external stimuli such as chemotherapy (CT) and photothermal therapy (PTT), leading to tumour resistance. As a key subcellular for autophagy, lysosomal dysfunction is crucial for autophagy suppression. Furthermore, lysosomal drug sequestration enhances basic drug resistance such as doxorubicin (DOX), which is trapped away from its target site, namely, the nucleus. Moreover, most of nanodrug delivery systems are internalised to lysosome for degradation, which further leads to DOX resistance. Lysosome serves as an essential organelle in drug resistance mechanisms, whose acidification arrest provides a potential strategy to inhibit autophagy and lysosomal drug sequestration simultaneously. The chloride channel-3 (ClC-3) protein is known as an important Cl−-H+ transporter to maintain lysosomal pH at low values of various human cells. Herein, a black phosphorus-based theranostic nanoplatform of BP-A-S@D is constructed, and HeLa cells are used as a model to verify the effect of ClC-3 on tumour lysosomal acidification and autophagy regulation. Consequently, ClC-3 silencing inhibits not only protective autophagy to sensitise chemo-photothermal therapy, but also DOX resistance by suppressing lysosomal acidification. Therefore, ClC-3 silencing could simultaneously inhibit autophagy and lysosomal drug sequestration to improve anti-tumour efficiency. [ABSTRACT FROM AUTHOR]

Background: Interleukin-24(IL-24), also referred to as melanoma differentiation-associated gene-7(mda-7), is a unique member of the IL-10 gene family, which displays nearly ubiquitous cancer-specific toxicity. The most notable feature of IL-24 is selectively induced growth suppression and apoptosis in various cancer cells, with no harmful effects toward normal cells. Autophagy is a self-protective mechanism in many kinds of tumor cells that respond to anticancer treatment. It is reported that autophagy inhibition could enhance the effects of many kinds of anticancer treatments, including gene therapy. However, whether IL-24 is effective to treat oral squamous cell carcinomas (OSCC) and if autophagy inhibition could improve the anticancer effect of IL-24 towards OSCC is has not been detected. Methods: MTT assays were carried out to determine the cell proliferation; Transfection was used to gene transfer; Western Blot was performed to detect the protein level of LC3II, P62, Beclin 1, Cleaved caspase-3, β-Tubulin and β-actin; Apoptosis rates and cell cycle alteration were analyzed using flow cytometry; Autophagy induction was confirmed by MDC staining, GFP-LC3 staining and transmission electron microscopy. Amount of IL-24 in the culture medium was quantified by ELISA. Apoptosis in vivo was analyzed by TUNEL assay. HE staining was used to observe the morphology of the samples. Results: In the present study, we proved that IL-24 have a novel anticancer effect towards KB cells and that autophagy inhibition could improve the anticancer effect of IL-24. IL-24 treated cells showed autophagy characteristics and autophagy inhibition by 3-methyladenine (3-MA) significantly enhanced IL-24-induced apoptosis. Similar results were obtained in the KB cells xenograft tumor model. Conclusions: These results suggest that the combination of autophagy inhibitors and IL-24 based on the AdLTR2EF1α- mediated gene transfer could be a promising way to cure OSCC. [ABSTRACT FROM AUTHOR]

Autophagy is a highly regulated catabolic process involving lysosomal degradation of intracellular components, damaged organelles, misfolded proteins, and toxic aggregates, reducing oxidative stress and protecting cells from damage. The process is also induced in response to various conditions, including nutrient deprivation, metabolic stress, hypoxia, anticancer therapeutics, and radiation therapy to adapt cellular conditions for survival. Autophagy can function as a tumor suppressor mechanism in normal cells and dysregulation of this process (ie, monoallelic Beclin-1 deletion) may lead to malignant transformation and carcinogenesis. In tumors, autophagy is thought to promote tumor growth and progression by helping cells to adapt and survive in metabolically-challenged and harsh tumor microenvironments (ie, hypoxia and acidity). Recent in vitro and in vivo studies in preclinical models suggested that modulation of autophagy can be used as a therapeutic modality to enhance the efficacy of conventional therapies, including chemo and radiation therapy. Currently, more than 30 clinical trials are investigating the effects of autophagy inhibition in combination with cytotoxic chemotherapies and targeted agents in various cancers. In this review, we will discuss the role, molecular mechanism, and regulation of autophagy, while targeting this process as a novel therapeutic modality, in various cancers. [ABSTRACT FROM AUTHOR]

Background/Aims: Glioblastoma multiforme (GBM) is the most malignant primary brain tumor with a poor prognosis. Combination treatment of autophagy inducer and autophagy inhibitor may be a feasible solution to improve the therapeutic effects. However, the correlation between them is unclear. The purpose of this study was to investigate the effect of autophagy inhibition at different stages on cytotoxicity of autophagy inducers in glioblastoma cells. Methods: Autophagy inhibition at early stage was achieved by 3-methyladenine (3-MA) or Beclin 1 shRNA. Autophagy inhibition at late stage was achieved by chloroquine (CQ) or Rab7 shRNA. Cell viability was assessed by MTT assay. Autophagy was measured using transmission electron microscopy and western blot. Apoptosis was measured using western blot and flow-cytometry. Results: Inhibition of early steps of autophagy by 3-MA or Beclin 1 knockdown decreased the toxic effect of arsenic trioxide (ATO) in GBM cell lines. In contrast, blockade of autophagy flux at late stage by CQ or Rab7 knockdown enhanced the cytotoxicity of ATO, and caused accumulation of degradative autophagic vacuoles and robust apoptosis. Moreover, depletion of Beclin 1 abolished the synergistic effect of ATO and CQ by reducing autophagy and apoptosis. Combination of CQ with other autophagy inducers also induced synergistic apoptotic cell death. Conclusion: These results suggest that inhibition of late process of autophagy, not initial step, increases the cytotoxic effect of autophagy inducers via autophagy and apoptosis, which may contribute to GBM chemotherapy. © 2015 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Atg7 is an autophagy-related gene, and is involved in two ubiquitin-like conjugation systems in the process of autophagy. It is well established that 3-methyladenine (3Ma) is an autophagy inhibitor. The present study aimed to investigate the effect of autophagy inhibition on the cell viability and cell cycle progression of human breast cancer cells. MDA-MB-231 human breast cancer cells were cultured in Dulbecco's modified Eagle's medium (DMEM) with high glucose, then divided into six groups. The six groups included the three fundamental groups as follows: The control group (untreated); the starvation group (high-glucose DMEM replaced with glucose-free minimal essential medium); and the starvation 3Ma group (maintained in glucose-free culture medium and treated with the autophagy inhibitor 3Ma). The three fundamental groups were further divided into Atg7 siRNA-transfected and non-transfected groups. The cell viability and apoptosis of each group was determined by MTT assay and flow cytometry. The results of the current study demonstrated that Atg7 deficiency alone had no statically significant effect on the cell viability of MDA-MB-231 human breast cancer cells, while 3Ma reduced the cell viability and its effect was potentiated by Atg7 deficiency. Atg7 deficiency was more intense than 3Ma in the promotion of apoptosis and cell arrest in G0/G1-phase in the absence of glucose and its effect was reduced by 3Ma. In conclusion, 3Ma and Atg7 may be involved in different pathways in the process of autophagy. Inhibition of autophagy may influence the cell viability and cell cycle through different pathways in MDA-MB-231 human breast cancer cells. [ABSTRACT FROM AUTHOR]

Context: Polyphyllin II (PPII) is a steroidal saponin isolated from Rhizoma Paridis . It exhibits significant antitumor activity such as anti-proliferation and pro-apoptosis in lung cancer., Objective: To explore whether PPII induce autophagy and the relationship between autophagy and apoptosis in non-small cell lung cancer (NSCLC) cells., Materials and Methods: The effects of PPII (0, 1, 5, and 10 μM) were elucidated by CCK8 assay, colony formation test, TUNEL staining, MDC method, and mRFP-GFP-LC3 lentivirus transfection in A549 and H1299 cells for 24 h. DMSO-treated cells were selected as control. The protein expression of autophagy (LC3-II, p62), apoptosis (Bcl-2, Bax, caspase-3) and p-mTOR was detected by Western blotting. We explored the relationship between autophagy and apoptosis by autophagy inhibitor CQ (10 μM) and 3-MA (5 mM)., Results: PPII (0, 1, 5, and 10 μM) inhibited the proliferation and induced apoptosis. The IC 50 values of A549 and H1299 cells were 8.26 ± 0.03 and 2.86 ± 0.83 μM. We found that PPII could induce autophagy. PPII promoted the formation of autophagosome, increased the expression of LC3-II/LC3-I ( p  < 0.05), while decreased p62 and p-mTOR ( p  < 0.05). Additionally, the co-treatment with autophagy inhibitors promoted the protein expression of c-caspase-3 and rate of Bax/Bcl-2 ( p  < 0.05), compared with PPII-only treatment group. Therefore, our results indicated that PPII-induced autophagy may be a mechanism to promote cell survival, although it can also induce apoptosis., Conclusions: PPII-induced apoptosis exerts its anticancer activity by inhibiting autophagy, which will hopefully provide a prospective compound for NSCLC treatment.

Abstract: Background: Cancer cells adapt to the stress resulting from accelerated cell growth and a lack of nutrients by activation of the autophagy pathway. Two proteins that allow cell growth in the face of metabolic stress and hypoxia are hypoxia-inducible factor-1α (HIF-1α) and heat shock protein 90 (Hsp 90). We hypothesize that chloroquine (CQ), an antimalarial drug that inhibits autophagosome function, in combination with either echinomycin, a HIF-1α inhibitor, or 17-dimethylaminoethylamino-17-dimethoxygeldanamycin (17-DMAG), an Hsp 90 inhibitor, will result in cytotoxicity in melanoma. Materials and methods: Multiple human melanoma cell lines (BRAF wild-type and mutant) were tested in vitro with CQ in combination with echinomycin or 17-DMAG. These treatments were performed in hypoxic (5% O2) and normoxic (18% O2) conditions. Mechanism of action was determined through Western blot of autophagy-associated proteins HIF-1α and Hsp 90. Results: Chloroquine, echinomycin, and 17-DMAG each induced cytotoxicity in multiple human melanoma cell lines, in both normoxia and hypoxia. Chloroquine combined with echinomycin achieved synergistic cytotoxicity under hypoxic conditions in multiple melanoma cell lines (BRAF wild-type and mutant). Western blot analysis indicated that echinomycin reduced HIF-1α levels, both alone and in combination with CQ. Changes in LC3 flux indicated inhibition of autophagy at the level of the autophagosome by CQ therapy. Conclusions: Targeting autophagy with the antimalarial drug CQ may be an effective cancer therapy in melanoma. Sensitivity to chloroquine is independent of BRAF mutational status. Combining CQ with the HIF-1α inhibitor echinomycin improves cytotoxicity in hypoxic conditions. [Copyright &y& Elsevier]

• MOF-containing sandwich-like 2D nanosheets were constructed via a mild method. • The targeted nanosheets showed the activatable drug release and OH generation. • The nanosheets possessed an effective cellular uptake and tumor enrichment. • The autophagy inhibition could promote the ROS-involved chemodynamic activity. The ingenious construction of transition metal-containing nanomaterials holds great potential for desired chemodynamic therapy (CDT). Herein, Cu2+-based porous metal–organic frameworks (MOFs) were laterally grown on the substrate of ultrathin sSiO 2 nanosheets (NSs) for high-efficiency chloroquine (CQ) loading, which was then modified by CD44-targeted hyaluronic acid (HA) to develop targeted sandwich-like two-dimensional (2D) NSs (HA-CQ/HT@sSiO 2 NSs) for activatable autophagy inhibition-primed CDT. Specifically, the obtained HA-CQ/HT@sSiO 2 NSs initiated the reduction of Cu2+ to Cu+ by depleting overexpressed glutathione (GSH), which concomitantly induced the decomposition of MOFs for controllable cargo unloading. The formed Cu+ then exerted Fenton-like catalyzing activity to generate detrimental hydroxyl radicals (OH) for ROS-involved CDT. Meanwhile, the released CQ was utilized to inhibit autophagy via blocking autolysosomes formation and degradation, thereby turning off self-protection pathway of oxidative stress for harvesting autophagy inhibition-primed chemodynamic activity. Particularly, HA-CQ/HT@sSiO 2 NSs could effectively accumulate at tumor site and be rapidly internalized into tumor cells benefiting from unique sheet-like morphology and CD44-targeting specificity. Both in vitro and in vivo results confirmed the potent autophagy inhibition-primed CDT effect, suggesting the activatable targeted sandwich-like 2D NSs may be referential to the creative design of therapy regimen. [ABSTRACT FROM AUTHOR]

• The approaches to overcome the limitations in photothermal therapy have been summarized, • The role of heat shock protein to (PTT) has been discussed. • The influence of metabolic process to PTT has been described. • The challenges and future outlooks of LTPTT are also discussed. Photothermal therapy (PTT) has received increasing attention due to its high selectivity, non-invasiveness, negligible drug resistance, oxygen independence, and minimal side effects. In PTT, photothermal agents (PTAs) absorb light energy and generate heat to kill cancer cells. Although various PTAs with strong near-infrared (NIR) light absorption and high photothermal conversion efficiency have been developed, their clinical uses in PTT still face with challenges. For example, maintaining a temperature of above 50°C for several minutes is needed to effectively ablate tumors, but this high temperature may destroy the surrounding normal tissues. Moreover, this rapid heating can induce an immune response that increases the cell tolerance to heat, which can weaken the therapeutic effects of PTT. In this review, we mainly focus on two approaches that have been developed to overcome the limitations of PTT, including inhibiting the expression of heat shock protein (Hsp) and regulating the metabolic processes of cells to develop low temperature PTT (LTPTT). We then discuss the existing challenges in clinical uses of LTPTT for treating tumors, and finally introduce future perspectives on the design of more effective therapeutic agents. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Autophagy is an important protective mechanism in maintaining or restoring cell homeostasis under physiological and pathological conditions. Nanoparticles (NPs) with certain components and morphologies can induce autophagic responses in cancer cells, providing a new perspective for establishing cancer therapy strategies. Herein, a novel nanodrug system, cell membranes-coated zeolitic imidazolate framework-8 (ZIF-8) NPs encapsulating chloroquine (CQ) and glucose oxidase (GOx) (defined as mCG@ZIF), is designed to achieve an enhanced anticancer effect with the combination of starvation therapy and an autophagy regulation strategy. It is found that ZIF-8 as a nanocarrier can induce autophagy to promote survival of cancer cells via the upstream Zn 2+ -stimulated mitochondrial reactive oxygen species (ROS) so that the anticancer effect is directly achieved by inhibiting this pro-survival autophagy using CQ released from mCG@ZIF under a tumor acidic microenvironment. Moreover, a cancer cell under starvation caused by GOx harnesses autophagy to maintain intracellular ATP levels and resist starvation therapy. The released CQ further inhibits the starvation-induced pro-survival autophagy and cuts off the protective pathway of cancer cells, enhancing the anticancer efficiency of GOx-based starvation therapy. Significantly, the cell membrane coating endows mCG@ZIF with excellent in vivo homotypic targeting ability. Both in vitro and in vivo results have confirmed the enhanced anticancer effect achieved by mCG@ZIF with a negligible side effect.

Background: Triple-negative breast cancer (TNBC) is a highly aggressive subtype of breast cancer that develops resistance to chemotherapy frequently. Autophagy has been reported as a pro-survival response to chemotherapeutic drugs in TNBC, and suppression of autophagy can be a strategy to overcome drug resistance., Methods: The efficacy of toosendanin (TSN) in blocking autophagy flux was measured by western blot analysis of autophagy markers, and the fluorescent imaging of RFP-GFP-LC3 probe. The co-localization of autophagosomes and lysosomes was analyzed by fluorescent imaging. Then, lysosome function was determined by measuring the lysosomal pH value and the activity of lysosomal hydrolytic proteases. For in vitro study, human triple-negative breast cancer MDA-MB-231 and MDA-MB-436 cell lines were used for evaluating the anti-proliferative effect. For in vivo study, the RFP-GFP-LC3 MDA-MB-231 xenograft nude mice received intraperitoneal injection of irinotecan (10 mg/kg), TSN (0.5 mg/kg) or a combination, and the autophagy activity and cell apoptosis were determined in tumor tissue. The degree of pathological injury of tissue was evaluated by liver index., Results: The natural autophagy inhibitor TSN, a triterpenoid extracted from Melia toosenda Sieb. et Zucc, potently inhibited late-stage autophagy in TNBC cells. This effect was achieved via elevating lysosome pH rather than blocking the fusion of autophagosomes and lysosomes. We further investigated the effects of TSN on the in vitro and in vivo TNBC models, in combination with chemotherapeutic drug irinotecan (or its active metabolite 7-ethyl-10-hydroxycamptothecin), a topoisomerase I inhibitor showing therapeutic potential for TNBC. The data showed that TSN blocked 7-ethyl-10-hydroxycamptothecin (SN-38)/irinotecan-induced protective autophagy, and significantly induced apoptosis in TNBC cells and tumor xenograft models when compared to SN-38/irinotecan alone group., (© 2022. The Author(s).)

Accumulating evidence suggests that autophagy dysfunction plays a critical role in myocardial ischemia/reperfusion (I/R) injury. However, the underling mechanism of malfunctional autophagy in the cardiomyocytes subjected to I/R has not been well defined. As a result, there is no effective therapeutic option by targeting autophagy to prevent myocardial I/R injury. Here, we used both an in vitro and an in vivo I/R model to monitor autophagic flux in the cardiomyocytes, by exposing neonatal rat ventricular myocytes to hypoxia/reoxygenation and by subjecting mice to I/R, respectively. We observed that the autophagic flux in the cardiomyocytes subjected to I/R was blocked in both in vitro and in vivo models. Down-regulating a lysosomal cationic channel, TRPML1, markedly restored the blocked myocardial autophagic flux induced by I/R, demonstrating that TRPML1 directly contributes to the blocked autophagic flux in the cardiomyocytes subjected to I/R. Mechanistically, TRPML1 is activated secondary to ROS elevation following ischemia/reperfusion, which in turn induces the release of lysosomal zinc into the cytosol and ultimately blocks the autophagic flux in cardiomyocytes, presumably by disrupting the fusion between autophagosomes and lysosomes. As a result, the inhibited myocardial autophagic flux induced by TRPML1 disrupted mitochondria turnover and resulted in mass accumulation of damaged mitochondria and further ROS release, which directly led to cardiomyocyte death. More importantly, pharmacological and genetic inhibition of TRPML1 channels greatly reduced infarct size and rescued heart function in mice subjected to I/R in vivo by restoring impaired myocardial autophagy. In summary, our study demonstrates that secondary to ROS elevation, activation of TRPML1 results in autophagy inhibition in the cardiomyocytes subjected to I/R, which directly leads to cardiomyocyte death by disrupting mitochondria turnover. Therefore, targeting TRPML1 represents a novel therapeutic strategy to protect against myocardial I/R injury., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany.)