Blue-Print Autophagy: Potential for Cancer Treatment

An organic extract from ascidian Ciona robusta induces cytotoxic autophagy in human malignant cell lines

The last decades have seen an increase in the isolation and characterization of anticancer compounds derived from marine organisms, especially invertebrates, and their use in clinical trials. In this regard, ascidians, which are included in the subphylum Tunicata, represent successful examples with two drugs, Aplidine© and Yondelis© that reached the market as orphan drugs against several malignancies. Here, we report that an organic extract prepared from homogenized tissues of the Mediterranean ascidian Ciona robusta inhibited cell proliferation in HT-29, HepG2, and U2OS human cells with the former being the most sensitive to the extract (EC50 = 250 μg/mL). We demonstrated that the ascidian organic extract was not cytotoxic on HT-29 cells that were induced to differentiate with sodium butyrate, suggesting a preference for the mixture for the malignant phenotype. Finally, we report that cell death induced by the organic extract was mediated by the activation of a process of cytotoxic autophagy as a result of the increased expression of the LC3-II marker and number of autophagic vacuoles, which almost doubled in the treated HT-29 cells. In summary, although the detailed chemical composition of the Ciona robusta extract is still undetermined, our data suggest the presence of bioactive compounds possessing anticancer activity.

Unraveling the mechanisms of intervertebral disc degeneration: an exploration of the p38 MAPK signaling pathway

Intervertebral disc (IVD) degeneration (IDD) is a worldwide spinal degenerative disease. Low back pain (LBP) is frequently caused by a variety of conditions brought on by IDD, including IVD herniation and spinal stenosis, etc. These conditions bring substantial physical and psychological pressure and economic burden to patients. IDD is closely tied with the structural or functional changes of the IVD tissue and can be caused by various complex factors like senescence, genetics, and trauma. The IVD dysfunction and structural changes can result from extracellular matrix (ECM) degradation, differentiation, inflammation, oxidative stress, mechanical stress, and senescence of IVD cells. At present, the treatment of IDD is basically to alleviate the symptoms, but not from the pathophysiological changes of IVD. Interestingly, the p38 mitogen-activated protein kinase (p38 MAPK) signaling pathway is involved in many processes of IDD, including inflammation, ECM degradation, apoptosis, senescence, proliferation, oxidative stress, and autophagy. These activities in degenerated IVD tissue are closely relevant to the development trend of IDD. Hence, the p38 MAPK signaling pathway may be a fitting curative target for IDD. In order to better understand the pathophysiological alterations of the intervertebral disc tissue during IDD and offer potential paths for targeted treatments for intervertebral disc degeneration, this article reviews the purpose of the p38 MAPK signaling pathway in IDD.

Identification of Anhydrodebromoaplysiatoxin as a Dichotomic Autophagy Inhibitor

Dysfunctional autophagy is associated with various human diseases, e.g., cancer. The discovery of small molecules modulating autophagy with therapeutic potential could be significant. To this end, we screened the ability of a series of metabolites isolated from marine microorganisms to modulate autophagy. Anhydrodebromoaplysiatoxin (ADAT), a metabolite yielded by the marine red algae Gracilaria coronopifolia, inhibited autophagosome-lysosome fusion in mammalian cells, thereby inducing the accumulation of autophagosomes. Treatment of cells with ADAT alkalinized lysosomal pH. Interestingly, ADAT also activated the mTOR/p70S6K/FoxO3a signaling pathway, likely leading to the inhibition of autophagy induction. ADAT had little effect on apoptosis. Our results suggest that ADAT is a dichotomic autophagy inhibitor that inhibits both late-stage (autophagosome-lysosome fusion) and early-stage (autophagy induction) autophagy.

The role of K63-linked polyubiquitin in several types of autophagy

Lysosomal-dependent self-degradative (autophagic) mechanisms are essential for the maintenance of normal homeostasis in all eukaryotic cells. Several types of such self-degradative and recycling pathways have been identified, based on how the cellular self material can incorporate into the lysosomal lumen. Ubiquitination, a well-known and frequently occurred posttranslational modification has essential role in all cell biological processes, thus in autophagy too. The second most common type of polyubiquitin chain is the K63-linked polyubiquitin, which strongly connects to some self-degradative mechanisms in the cells. In this review, we discuss the role of this type of polyubiquitin pattern in numerous autophagic processes.

Circ_0020123 plays an oncogenic role in non-small cell lung cancer depending on the regulation of miR-512-3p/CORO1C

Background

Non‐small cell lung cancer (NSCLC) is one of the leading causes responsible for cancer‐associated death globally. The aim of this study was to illustrate the function of circular RNA_0020123 (circ_0020123) in NSCLC progression and its associated mechanism.

Methods

RNA and protein expression was determined by reverse transcription‐quantitative polymerase chain reaction (RT‐qPCR) and western blot assay. Cell proliferation, migration, invasion, angiogenesis, apoptosis and autophagy were analyzed to assess the role of circ_0020123/microRNA‐512‐3p (miR‐512‐3p)/coronin 1C (CORO1C) axis in NSCLC cells. Tumorigenesis in nude mice was analyzed to determine the in vivo role of circ_0020123. The intermolecular target relation was confirmed by dual‐luciferase reporter and RNA immunoprecipitation (RIP) assays.

Results

Circ_0020123 expression was aberrantly upregulated in NSCLC tissues and cell lines. Circ_0020123 interference markedly restrained cell proliferation, migration, invasion, angiogenesis and autophagy and induced cell apoptosis of NSCLC cells. Circ_0020123 knockdown suppressed xenograft tumor growth in vivo. Circ_0020123 acted as a molecular sponge for miR‐512‐3p. Circ_0020123 silencing‐induced effects in NSCLC cells were largely reversed by the knockdown of miR‐512‐3p. miR‐512‐3p interacted with the 3′ untranslated region (3′UTR) of CORO1C. CORO1C overexpression largely reversed miR‐512‐3p accumulation‐induced influences in NSCLC cells. Circ_0020123 positively regulated CORO1C expression by sponging miR‐512‐3p in NSCLC cells.

Conclusion

Circ_0020123 aggravated NSCLC progression by binding to miR‐512‐3p to induce CORO1C expression, which provided new potential targets for the treatment of NSCLC.

Unravelling the Anti-Inflammatory and Antioxidant Potential of the Marine Sponge Cliona celata from the Portuguese Coastline

Inflammation is a double-edged sword, as it can have both protective effects and harmful consequences, which, combined with oxidative stress (OS), can lead to the development of deathly chronic inflammatory conditions. Over the years, research has evidenced the potential of marine sponges as a source of effective anti-inflammatory therapeutic agents. Within this framework, the purpose of this study was to evaluate the antioxidant and the anti-inflammatory potential of the marine sponge Cliona celata. For this purpose, their organic extracts (C1-C5) and fractions were evaluated concerning their radical scavenging activity through 2,2-diphenyl-1-picrylhydrazyl radical (DPPH), ferric reducing antioxidant power (FRAP), oxygen radical absorbance capacity (ORAC), and anti-inflammatory activity through a (lipopolysaccharides (LPS)-induced inflammation on RAW 264.7 cells) model. Compounds present in the two most active fractions (F5 and F13) of C4 were tentatively identified by gas chromatography coupled to mass spectrometry (GC-MS). Even though samples displayed low antioxidant activity, they presented a high anti-inflammatory capacity in the studied cellular inflammatory model when compared to the anti-inflammatory standard, dexamethasone. GC-MS analysis led to the identification of n-hexadecanoic acid, cis-9-hexadecenal, and 13-octadecenal in fraction F5, while two major compounds, octadecanoic acid and cholesterol, were identified in fraction F13. The developed studies demonstrated the high anti-inflammatory activity of the marine sponge C. celata extracts and fractions, highlighting its potential for further therapeutic applications.

MAPK /ERK signaling pathway: A potential target for the treatment of intervertebral disc degeneration

Intervertebral disc degeneration (IDD) is a chronic skeletal muscle degenerative disease, which is considered the main cause of low back pain. It seriously affects the quality of life of patients and consequently brings a heavy economic burden to their families and the society. Although IDD is considered a natural process in degenerative lesions, it is mainly caused by aging, trauma, genetic susceptibility and other factors. It is closely related to changes in the tissue structure and function, including the progressive destruction of extracellular matrix, cell aging, cell death of the intervertebral disc (IVD), inflammation, and impairment of tissue biomechanical function. Currently, the treatment of IDD is aimed at alleviating symptoms rather than at targeting pathological changes in the IVD. Furthermore, the mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) signaling pathway is closely related to various pathological processes in IDD, and the activation of the MAPK/ERK pathway promotes the degradation of the IVD extracellular matrix, cell aging, apoptosis, and inflammatory responses. It also induces autophagy and oxidative stress that accelerate the IVD process. In our current review, we summarize the latest developments in the negative regulation of IDD after activation of the MAPK/ERK signaling pathway and emphasize on its influence on IDD. Targeting this pathway may become an attractive treatment strategy for IDD in the near future.

Therapeutic potential of marine peptides in glioblastoma: Mechanistic insights

Glioblastoma multiforme (GBM) is the most common primary malignant brain tumor in humans. It is characterized by excessive cell growth and accelerated intrusion of normal brain tissue along with a poor prognosis. The current standard of treatment, including surgical removal, radiation therapy, and chemotherapy, is largely ineffective, with high mortality and recurrence rates. As a result, traditional approaches have evolved to include new alternative remedies, such as natural compounds. Aquatic species provide a rich supply of possible drugs. The physiological effects of marine peptides in glioblastoma are mediated by a range of pathways, including apoptosis, microtubule balance disturbances, suppression of angiogenesis, cell migration/invasion, and cell viability; autophagy and metabolic enzymes downregulation. Herein, we address the efficacy of marine peptides as putative safe therapeutic agents for glioblastoma coupled with detail molecular mechanisms.

Systematic profiling of diagnostic and prognostic value of autophagy-related genes for sarcoma patients

BACKGROUND

Autophagy-related genes (ARGs) have been confirmed to have an important role in tumorigenesis and tumor microenvironment formation. Nevertheless, a systematic analysis of ARGs and their clinical significance in sarcoma patients is lacking.

METHODS

Gene expression files from The Cancer Genome Atlas (TCGA) database and Genotype-Tissue Expression (GTEx) were used to select differentially expressed genes (DEGs). Differentially expressed ARGs (DEARGs) were determined by matching the DEG and HADb gene sets, which were evaluated by functional enrichment analysis. Unsupervised clustering of the identified DEARGs was conducted, and associations with tumor microenvironment (TME), immune checkpoints, and immune cells were analyzed simultaneously. Two prognostic signatures, one for overall survival (OS) and one for disease-free survival (DFS), were established and validated in an independent set.

RESULTS

In total, 84 DEARGs and two clusters were identified. TME scores, five immune checkpoints, and several types of immune cells were found to be significantly different between two clusters. Two prognostic signatures incorporating DEARGs showed favorable discrimination and were successfully validated. Two nomograms combining signature and clinical variables were generated. The C-indexes were 0.818 and 0.747 for the OS and DFS nomograms, respectively.

CONCLUSION

This comprehensive analyses of the ARG landscape in sarcoma showed novel ARGs related to carcinogenesis and the immune microenvironment. These findings have implications for prognosis and therapeutic responses, which reveal novel potential prognostic biomarkers, promote precision medicine, and provide potential novel targets for immunotherapy.

Blue-Print Autophagy in 2020: A Critical Review

Autophagy is an elegant and complex biological process that has recently attracted much attention from the scientific community. The compounds which are capable of control and modulation of this process have a promising potential as therapeutics for a number of pathological conditions, including cancer and neurodegenerative disorders. At the same time, due to the relatively young age of the field, there are still some pitfalls in the autophagy monitoring assays and interpretation of the experimental data. This critical review provides an overview of the marine natural compounds, which have been reported to affect autophagy. The time period from the beginning of 2016 to the middle of 2020 is covered. Additionally, the published data and conclusions based on the experimental results are re-analyzed with regard to the guidelines developed by Klionsky and colleagues (Autophagy. 2016; 12(1): 1–222), which are widely accepted by the autophagy research community. Remarkably and surprisingly, more than half of the compounds reported to be autophagy activators or inhibitors could not ultimately be assigned to either category. The experimental data reported for those substances could indicate both autophagy activation and inhibition, requiring further investigation. Thus, the reviewed molecules were divided into two groups: having validated and non-validated autophagy modulatory effects. This review gives an analysis of the recent updates in the field and raises an important problem of standardization in the experimental design and data interpretation.

Repurposing Ziyuglycoside II Against Colorectal Cancer via Orchestrating Apoptosis and Autophagy

Effective chemotherapy drugs for colorectal cancer remain a challenge. In this research, Ziyuglycoside II (Ziyu II), exhibits considerable antitumor activity against CRC cells both in vitro and in vivo. The results showed that Ziyu II induced apoptosis through the accumulation of reactive oxygen species (ROS), which was necessary for Ziyu II to inhibit colorectal cancer cells. Intriguingly, The treatment of Ziyu II triggered complete autophagic flux in CRC cells. Inhibition of autophagy partially reversed Ziyu II-induced growth inhibition, demonstrating a cytotoxic role of autophagy in response to Ziyu II-treated. Mechanism indicated that Ziyu II-induced autophagy by inhibiting Akt/mTOR pathway. Akt reactivation partially reduced Ziyu II-induced LC3-II turnover and LC3 puncta accumulation. Especially, Ziyu II improves the sensitivity of 5-fluorouracil which is the first-line chemotherapy drug in colorectal cancer cells. This research provides novel insight into the molecular mechanism of Ziyu II’s anti-proliferation, including apoptosis and autophagy, and lays a foundation for the potential application of Ziyu II in clinical CRC treatment.

BAY60-2770 attenuates doxorubicin-induced cardiotoxicity by decreased oxidative stress and enhanced autophagy

BACKGROUND

Doxorubicin (DOX) administration decreases cardiac soluble guanylate cyclase (sGC) activity. We hypothesized that bypassing impaired NO-sGC-cGMP pathway resulting from the activation of oxidized and heme-free soluble guanylate cyclase (sGC) could be a therapeutic target for DOX-mediated cardiomyopathy (DOX-CM). The present study investigated the therapeutic roles and mechanism of BAY60-2770, an activator of oxidized sGC, in alleviating DOX-CM.

METHODS

H9c2 cardiomyocytes were pretreated with BAY60-2770 followed by DOX. Cell viability and intracellular reactive oxygen species (ROS) were subsequently measured. To determine the role BAY60-2770 in mitochondrial ROS generation and mitochondrial membrane potential, we examined mitoSOX RED and TMRE fluorescence under DOX exposure. As animal experiments, rats were orally administered with 5 mg/kg of BAY60-2770 at 1 h prior to every DOX treatment and then assessed by echocardiography and apoptotic marker and autophagy.

RESULTS

BAY60-2770 ameliorated cell viability and DOX-induced oxidative stress in H9c2 cells, which was mediated by PKG activation. Mitochondrial ROS and TMRE fluorescence were attenuated by BAY60-2770 in DOX-treated H9c2 cells. DOX-induced caspase-3 activation decreased after pretreatment with BAY60-2770 in vivo and in vitro. Echocardiography showed that BAY60-2770 significantly improved DOX-induced myocardial dysfunction. Autophagosome was increased by BAY60-2770 in vivo.

CONCLUSIONS

BAY60-2770 appears to mitigate DOX-induced mitochondrial ROS, membrane potential loss, autophagy, and subsequent apoptosis, leading to protection of myocardial injury and dysfunction. These novel results highlighted the therapeutic potential of BAY60-2770 in preventing DOX-CM.

The Role of Deubiquitinating Enzymes in the Various Forms of Autophagy

Deubiquitinating enzymes (DUBs) have an essential role in several cell biological processes via removing the various ubiquitin patterns as posttranslational modification forms from the target proteins. These enzymes also contribute to the normal cytoplasmic ubiquitin pool during the recycling of this molecule. Autophagy, a summary name of the lysosome dependent self-degradative processes, is necessary for maintaining normal cellular homeostatic equilibrium. Numerous forms of autophagy are known depending on how the cellular self-material is delivered into the lysosomal lumen. In this review we focus on the colorful role of DUBs in autophagic processes and discuss the mechanistic contribution of these molecules to normal cellular homeostasis via the possible regulation forms of autophagic mechanisms.

Microvesicles derived from human Wharton's jelly mesenchymal stem cells enhance autophagy and ameliorate acute lung injury via delivery of miR-100

Objectives

Microvesicles (MVs) derived from human Wharton’s jelly mesenchymal stem cells (MSC-MVs) were demonstrated to ameliorate acute lung injury (ALI). We have previously found that MSC-MV-transferred hepatocyte growth factor was partly involved in their therapeutic effects. Since MSC-MVs also contained a substantial quantity of miR-100, which plays an important role in lung cancer and injury, we speculated that miR-100 might similarly account for a part of the therapeutic effects of MSC-MVs.

Methods

MSCs were transfected with miR-100 inhibitor to downregulate miR-100 in MSC-MVs. A rat model of ALI and cell injury in rat type II alveolar epithelial cell line (L2) was induced by bleomycin (BLM). A co-culture model of alveolar epithelial cells and MSC-MVs was utilized to examine the therapeutic role of MSC-MVs and mechanism.

Results

MSC-MV treatment attenuated BLM-induced apoptosis and inflammation in BLM-treated L2 cells and ameliorated BLM-induced lung apoptosis, inflammation, and fibrosis in BLM-induced ALI rats. The beneficial effect of MSC-MVs was partly eliminated when miR-100 was knocked down in MSCs. Moreover, MSC-MV-transferred miR-100 mediated the therapeutic effect of MSC-MVs in ALI through enhancing autophagy by targeting mTOR.

Conclusion

MSC-MVs enhance autophagy and ameliorate ALI partially via delivery of miR-100.

Astrocyte-derived exosomes transfer miR-190b to inhibit oxygen and glucose deprivation-induced autophagy and neuronal apoptosis

Our previous work has verified that astrocytes (AS)-derived exosomes (AS-Exo) inhibited autophagy and ameliorated neuronal damage in experimental ischemic stroke. However, the mechanism of AS-Exo regulation of autophagy remains unclear. The aim of this study was to investigate the regulatory mechanism of AS-Exo on neuronal autophagy. The mouse hippocampal neuronal cell line HT-22 was cultured in oxygen and glucose deprivation (OGD) condition to mimic ischemic injury. The primary astrocytes were used to isolate exosomes. Exosome labeling and uptake by HT-22 cells were observed by confocal laser microscopy. miR-190b expression was determined by qRT-PCR. HT-22 cell vitality and apoptosis were determined by CCK-8 assay and TUNEL staining, respectively. Levels of TNF-α, IL-6 and IL-1β were analyzed by ELISA. Protein levels of apoptosis-related cleaved caspase-3, Bax, Bcl-2 and autophagy-related Beclin-1, LC3-I/II, Atg7, P62 were determined by western blot. A dual-luciferase reporter assay was performed to confirm the direct interaction between miR-190b and Atg7. miR-190b expression in AS-Exo was found to be significantly higher than that in AS. AS-Exo-mediated transfer of miR-190b attenuated OGD-induced neuronal apoptosis via suppressing autophagy. Moreover, Atg7 was identified as a target of miR-190b. AS-Exo-mediated transfer of miR-190b regulated autophagy by targeting Atg7. Collectively, our data indicated that AS-Exo transferred miR-190b to inhibit OGD-induced autophagy and neuronal apoptosis.

Autophagy-deficient mice are more susceptible to engrafted leukemogenesis

Autophagy is primarily considered as an important survival mechanism for both normal cells and cancer cells in response to metabolic stress or chemotherapy; but the role of autophagy in leukemogenesis is not fully understood. The aim of this study is to explore the role of intrinsic autophagy in the leukemogenesis of B-cell acute lymphoblastic leukemia (B-ALL). In this study, conditional knockout mice Atg7^f/f;Ubc-Cre, in which an autophagy-essential gene Atg7 is universally deleted, were used as recipients, B-ALL cell line 697 was used as donor cells to generate leukemia mouse model. Compared to wild-type mice, Atg7 knockout mice were more susceptible to engrafted leukemogenesis, shown by increase in white blood cells, lymphocytes, and platelets, decrease in HSPC number and its colony-forming unit (CFU). The liver and spleen displayed hepatosplenomegaly and inflammatory cell infiltration. Furthermore, second competitive transplantation revealed dysfunction of the HSPC in Atg7-knockout leukemia mice represented by destructive self-renew ability (CFU) and reconstitution ability including decreased B220, Ter 119 cells, and increased Gr-1 cell percentage. In summary, Mice with universal deletion of Atg7 are more inclined to the occurrence of engrafted human leukemia, which is largely attributed to the deterioration of the function of HSPC in autophagy deficient mice.

Maternal pentachlorophenol exposure induces developmental toxicity mediated by autophagy on pregnancy mice

Pentachlorophenol (PCP) is often used as chlorinated hydrocarbon herbicides and insecticides, which has been suggested that toxicity of carcinogenic effect, teratogenic effect and reproductive system. However, there was still precious known about the underlying molecular mechanism of PCP on mammalian early development. To explore the developmental toxicity of PCP and its potential mechanism, pregnancy ICR mice except controls were exposed to PCP (0.02, 0.2 or 2 mg/kg) during gestation day (GD) 0.5 to GD8.5 in this study. We found that the fetal loss rate was increased and placental chorionic villi structure was disorder in hematoxylin-eosin staining (HE) on GD16.5. Meanwhile, autophagosomes were observed in chorionic villi through Transmission Electron Microscope (TEM). Moreover, the mRNA and/or protein expression of P62, LC3-ІІ/LC3-І and Beclin1 were increased in placenta, indicating the occurrence of autophagy. Then, to further explore the autophagy mechanism, microRNA (miR)-30a-5p, an expression inhibitor of Beclin1, was predicted through bioinformatics predictions and RT-PCR, and it was reduced in PCP-treated mice. Transfection and luciferase reporter gene test were used to verify the interaction between Beclin1 and miR-30a-5p. These results firstly indicate that, PCP exposure could downregulate the expression of miR-30a-5p, and then induced autophagy through upregulation of Beclin1 to result in fetal loss. Our study laid a foundation for understanding the PCP developmental toxicity through autophagy.

mTOR independent alteration in ULK1 Ser758 phosphorylation following chronic LRRK2 kinase inhibition

Unc-51 Like Kinase 1 (ULK1) is a critical regulator of the biogenesis of autophagosomes, the central component of the catabolic macroautophagy pathway. Regulation of ULK1 activity is dependent upon several phosphorylation events acting to repress or activate the enzymatic function of this protein. Phosphorylation of Ser758 ULK1 has been linked to repression of autophagosome biogenesis and was thought to be exclusively dependent upon mTOR complex 1 kinase activity. In the present study, a novel regulation of Ser758 ULK1 phosphorylation is reported following prolonged inhibition of the Parkinson’s disease linked protein leucine rich repeat kinase 2 (LRRK2). Here, modulation of Ser758 ULK1 phosphorylation following LRRK2 inhibition is decoupled from the repression of autophagosome biogenesis and independent of mTOR complex 1 activity.

Role of autophagy in breast cancer and breast cancer stem cells (Review)

Autophagy is a key catabolic process, in which cytosolic cargo is engulfed by the formation of a double membrane and then degraded through the fusing of autophagosomes with lysosomes. Autophagy is a constitutively active, evolutionarily conserved, catabolic process important for the maintenance of homeostasis in cellular stress responses and cell survival. Although the mechanisms of autophagy have not yet been fully elucidated, emerging evidence suggests that it plays a dual role in breast cancer and in maintaining the activity of breast cancer stem cells (CSCs). However, it may play a complex role in breast CSC therapy. Breast CSCs, a population of cells with the ability to self-renew, differentiate, and initiate and sustain tumor growth, play an essential role in cancer recurrence, anticancer resistance and metastasis. In addition, the elucidation of the association between autophagy and apoptosis in the tumor context is crucial in order to better address appropriate therapy strategies. In the present review, a summary of the mechanisms and roles of autophagy in breast cancer and CSCs is presented. The potential value of such autophagy modulators in the development of novel breast cancer therapies is discussed.

miR-138-5p suppresses autophagy in pancreatic cancer by targeting SIRT1

The role of microRNA in the aberrant autophagy that occurs in pancreatic cancer remains controversial. Because hypoxia is known to induce autophagy, we screened for differentially expressed microRNAs using a miRNA microarray with pancreatic cancer cells cultured under normoxic and hypoxic conditions. We found that miR-138-5p was among the most downregulated miRNA in hypoxia-stimulated cells, and that overexpression of miR-138-5p substantially reduced expression of autophagy markers. In addition, western blot and immunofluorescence analyses and electron microscopy revealed that miR-138-5p inhibited autophagy in pancreatic cancer cells and blocked serum starvation-induced autophagic flux independently of the typical autophagic signaling pathway. miR-138-5p had no effect on ATG3, ATG5, or ATG7, three primary autophagy-associated genes. Instead, miR-138-5p specifically targeted the SIRT1 3' untranslated region and suppressed autophagy by reducing the level of SIRT1, which acetylates FoxO1 and regulates autophagy via FoxO1/Rab7. SIRT1 or Rab7 knockdown blocked the SIRT1/FoxO1/Rab7 axis and suppressed autophagic inhibition by miR-138-5p. Finally, we found that miR-138-5p inhibited autophagy and tumor growth in vivo. These results indicate that miR-138-5p suppresses autophagy in pancreatic cancer by targeting SIRT1.

The PI3K/Akt pathway: a critical player in intervertebral disc degeneration

Intervertebral disc degeneration (IDD) is thought to be the primary cause of low back pain, a severe public health problem worldwide. Current therapy for IDD aims to alleviate the symptoms and does not target the underlying pathological alternations within the disc. Activation of the phosphatidylinositol 3-kinase (PI3K)/Akt pathway protects against IDD, which is attributed to increase of ECM content, prevention of cell apoptosis, facilitation of cell proliferation, induction or prevention of cell autophagy, alleviation of oxidative damage, and adaptation of hypoxic microenvironment. In the current review, we summarize recent progression on activation and negative regulation of the PI3K/Akt signaling pathway, and highlight its impact on IDD. Targeting this pathway could become an attractive therapeutic strategy for IDD in the near future.

Autophagy as a potential target for sarcoma treatment

Autophagy is a constitutively active, evolutionary conserved, catabolic process for maintaining homeostasis in cellular stress responses and cell survival. Although its mechanism has not been fully illustrated, recent work on autophagy in various types of sarcomas has demonstrated that autophagy exerts an important role in sarcoma cell growth and proliferation, in pro-survival response to therapies and stresses, and in therapeutic resistance of sarcoma. Thus, the autophagic process is being seen as a possibly novel therapeutic target of sarcoma. Additionally, some co-regulators of autophagy have also been investigated as promising biomarkers for the diagnosis and prognosis of sarcoma. In this review, we summarize contemporary advances in the role of autophagy in sarcoma and discuss the potential of autophagy as a new target for sarcoma treatment.