Autophagy-related cell death by pan-histone deacetylase inhibition in liver cancer

Role of autophagy-related genes in liver cancer prognosis

Autophagy, a highly conserved process of protein and organelle degradation, has emerged as a critical regulator in various diseases, including cancer progression. In the context of liver cancer, the predictive value of autophagy-related genes remains ambiguous. Leveraging chip datasets from the TCGA and GTEx databases, we identified 23 differentially expressed autophagy-related genes in liver cancer. Notably, five key autophagy genes, PRKAA2, BIRC5, MAPT, IGF1, and SPNS1, were highlighted as potential prognostic markers, with MAPT showing significant overexpression in clinical samples. In vitro cellular assays further demonstrated that MAPT promotes liver cancer cell proliferation, migration, and invasion by inhibiting autophagy and suppressing apoptosis. Subsequent in vivo studies further corroborated the pro-tumorigenic role of MAPT by suppressing autophagy. Collectively, our model based on the five key genes provides a promising tool for predicting liver cancer prognosis, with MAPT emerging as a pivotal factor in tumor progression through autophagy modulation.

Panobinostat (LBH589) combined with AM1241 induces cervical cancer cell apoptosis through autophagy pathway

PURPOSE

The study aims to investigate the apoptotic effects of combining LBH589 and AM1241 (a selective CB2 receptor agonist) on cervical cancer cells and elucidating the mechanism of this combined therapy, which may provide innovative strategies for treating this disease.

METHODS

The viability of the cervical cancer cells was measured by cell counting kit-8 (CCK-8) assay, and the synergistic effect was analyzed using SynergyFinder. Cell proliferation was tested by cell cloning. The apoptosis and reactive oxygen species (ROS) production in cervical cancer cells were analyzed by flow cytometry. Western blot and quantitative real-time PCR (qRT-PCR) were employed to determine changes in protein and gene levels of pathway-related factors.

RESULTS

By the results of cytotoxicity assay, SiHa cells were selected and treated with 0.1 μM LBH589 and 4 μM AM1241 for 24 h for subsequent experiments. The combination of both was synergistic as determined by bliss, ZIP, HSA and LOEWE synergy score. Plate cloning results showed that LBH589 combined with AM1241 inhibited the proliferation of cervical cancer cells compared to individual drug. Additionally, compared with LBH589 alone, the combination of LBH589 and AM1241 induced autophagy by increasing LC3II/LC3I and decreasing P62/GAPDH, leading to a significantly higher rate of apoptosis. Pharmacological inhibition of also inhibited apoptosis. Consistently, we found that the endoplasmic reticulum, DNA damage repair pathway were induced after co-administration. Furthermore, cellular ROS increased after co-administration, and apoptosis was inhibited by the addition of ROS scavenger.

CONCLUSION

LBH589 combined with AM1241 activated the endoplasmic reticulum emergency pathway, DNA damage repair signaling pathway, oxidative stress and autophagy pathway, ultimately promoting the apoptosis of cervical cancer cells. These findings suggest that the co-administration of LBH589 and AM1241 may be a new treatment plan for the treatment of cervical cancer.

Asiatic acid alleviates cisplatin-induced renal fibrosis in tumor-bearing mice by improving the TFEB-mediated autophagy-lysosome pathway

Nephrotoxicity is a major side effect of cisplatin treatment of solid tumors in the clinical setting. Long-term low-dose cisplatin administration causes renal fibrosis and inflammation. However, few specific medicines with clinical application value have been developed to reduce or treat the nephrotoxic side effects of cisplatin without affecting its tumor-killing effect. The present study analyzed the potential reno-protective effect and mechanism of asiatic acid (AA) in long-term cisplatin-treated nude mice suffering from tumors. AA treatment significantly attenuated renal injury, inflammation, and fibrosis induced by long-term cisplatin injection in tumor-bearing mice. AA administration notably suppressed tubular necroptosis and improved the autophagy-lysosome pathway disruption caused by chronic cisplatin treatment in tumor-transplanted nude mice and HK-2 cells. AA promoted transcription factor EB (TFEB)-mediated lysosome biogenesis and reduced the accumulation of damaged lysosomes, resulting in enhanced autophagy flux. Mechanistically, AA increased TFEB expression by rebalancing Smad7/Smad3, whereas siRNA inhibition of Smad7 or TFEB abolished the effect of AA on autophagy flux in HK-2 cells. In addition, AA treatment did not weaken, but actually enhanced the anti-tumor effect of cisplatin, as evidenced by the promoted tumor apoptosis and inhibited proliferation in nude mice. In summary, AA alleviates cisplatin-induced renal fibrosis in tumor-bearing mice by improving the TFEB-mediated autophagy-lysosome pathway.

Synergic Induction of Autophagic Cell Death in Anaplastic Thyroid Carcinoma

Anaplastic thyroid carcinoma (ATC) has poor prognosis, high mortality rate and lack of effective therapy. A synergic combination of PD-L1 antibody together with cell death promoting substances like deacetylase inhibitors (DACi) and multi-kinase inhibitors (MKI) could sensitize ATC cells and promote decay by autophagic cell death. The PD-L1-inhibitor atezolizumab synergized with panobinostat (DACi) and sorafenib (MKI) leading to significant reduction of the viability, measured by real time luminescence, of three different patient-derived primary ATC cells, of C643 cells and follicular epithelial thyroid cells too. Solo administration of these compounds caused a significant over-expression of autophagy transcripts; meanwhile autophagy proteins were almost not detectable after the single administration of panobinostat, thus supporting a massive autophagy degradation process. Instead, the administration of atezolizumab caused an accumulation of autophagy proteins and the cleavage of the active caspases 8 and 3. Interestingly, only panobinostat and atezolizumab were able to exacerbate the autophagy process by increasing the synthesis, the maturation and final fusion with the lysosomes of the autophagosome vesicles. Despite ATC cells could be sensitized by atezolizumab via the cleavage of the caspases, no reduction of cell proliferation or promotion of cell death was observed. The apoptosis assay evidenced the ability of panobinostat alone and in combination with atezolizumab to induce the phosphatidil serine exposure (early apoptosis) and further the secondary necrosis. Instead, sorafenib was only able to cause necrosis. The increase of caspases activity induced by atezolizumab, the apoptosis and autophagy processes promoted by panobinostat synergize thus promoting cell death in well-established and primary anaplastic thyroid cancer cells. The combined therapy could represent a future clinical application for the treatment of such lethal and untreatable solid cancer.

The epigenetic regulation of cancer cell recovery from therapy exposure and its implications as a novel therapeutic strategy for preventing disease recurrence

The ultimate goal of cancer therapy is the elimination of disease from patients. Most directly, this occurs through therapy-induced cell death. Therapy-induced growth arrest can also be a desirable outcome, if prolonged. Unfortunately, therapy-induced growth arrest is rarely durable and the recovering cell population can contribute to cancer recurrence. Consequently, therapeutic strategies that eliminate residual cancer cells reduce opportunities for recurrence. Recovery can occur through diverse mechanisms including quiescence or diapause, exit from senescence, suppression of apoptosis, cytoprotective autophagy, and reductive divisions resulting from polyploidy. Epigenetic regulation of the genome represents a fundamental regulatory mechanism integral to cancer-specific biology, including the recovery from therapy. Epigenetic pathways are particularly attractive therapeutic targets because they are reversible, without changes in DNA, and are catalyzed by druggable enzymes. Previous use of epigenetic-targeting therapies in combination with cancer therapeutics has not been widely successful because of either unacceptable toxicity or limited efficacy. The use of epigenetic-targeting therapies after a significant interval following initial cancer therapy could potentially reduce the toxicity of combination strategies, and possibly exploit essential epigenetic states following therapy exposure. This review examines the feasibility of targeting epigenetic mechanisms using a sequential approach to eliminate residual therapy-arrested populations, that might possibly prevent recovery and disease recurrence.

Panobinostat inhibits breast cancer progression via Vps34-mediated exosomal pathway

Exosomes play crucial roles in intercellular communication, including tumor metastasis. Panobinostat (LBH589), a histone deacetylases (HDAC) inhibitor, is an emerging anti-tumor drug with promising efficacy in cancer therapy. This study was set out from recent evidence that exosome was a mechanism of intercellular drug transfer with significant pharmacological consequences. It enlightened us LBH589 might regulate tumor growth through exosomal secretion. Here we demonstrated LBH589 induced autophagy and facilitated secretory autophagy. Furthermore, LBH589 dose- and time-dependently stimulated exosomal release mediated by Vps34/Rab5C pathway, documented by the ablation of Vps34 and/or Rab5C in breast cancer cells. Additionally, the findings also presented LBH589 inhibited breast cancer progression via exosomes. Altogether, we revealed a novel mechanism of LBH589 in exosome-mediated anti-tumor effects in breast cancer. The schematic diagram of signaling pathways involved in the suppression of breast cancer progression by LBH589 via exosomes.

Long Non-Coding RNA H19 Expression Correlates with Autophagy Process in Adrenocortical Carcinoma

Adrenocortical carcinoma (ACC) is characterized by poor prognosis and high mortality. The suppression of the long-non-coding RNA H19, counterbalanced by IGF2 over-expression, leads to down-regulation of the autophagy markers, high proliferation rate and metastatic potential in patients affected by ACC. The administration of the deacetylase inhibitors (DACi) panobinostat, trichostatin A (TSA) and SAHA affected the cell viability of H295R monolayer and spheroids and induced the over-expression of H19 and autophagy transcripts. H19 knock down in H295R cells was not able to modulate the expression level of autophagy transcripts. Instead, H19 knock down was able to impede the ability of DACi to modulate the protein level of the autophagy markers. Furthermore, the administration of higher concentration of DACi was able to down-regulate the protein level of Beclin1 and p62 and to induce the conversion of LC3B-I into the active LC3B-II form, thus confirming an active autophagic process. Neither the active protein level nor the activity of caspases 8 and 3 was prompted by the DACi, thus excluding the involvement of the executioners of apoptosis in H295R decay. The DACi restore H19, the autophagy markers and trigger cell death in ACC cells. The re-activation of autophagy would represent a novel strategy for the treatment of patients affected by this severe malignancy.

Vorinostat in autophagic cell death: A critical insight into autophagy-mediated, -associated and -dependent cell death for cancer prevention

Histone deacetylases (HDACs) inhibit the acetylation of crucial autophagy genes, thereby deregulating autophagy and autophagic cell death (ACD) and facilitating cancer cell survival. Vorinostat, a broad-spectrum pan-HDAC inhibitor, inhibits the deacetylation of key autophagic markers and thus interferes with ACD. Vorinostat-regulated ACD can have an autophagy-mediated, -associated or -dependent mechanism depending on the involvement of apoptosis. Molecular insights revealed that hyperactivation of the PIK3C3/VPS34-BECN1 complex increases lysosomal disparity and enhances mitophagy. These changes are followed by reduced mitochondrial biogenesis and by secondary signals that enable superactivated, nonselective or bulk autophagy, leading to ACD. Although the evidence is limited, this review focuses on molecular insights into vorinostat-regulated ACD and describes critical concepts for clinical translation.

Targeting Ferroptosis for Lung Diseases: Exploring Novel Strategies in Ferroptosis-Associated Mechanisms

Ferroptosis is an iron-dependent regulated necrosis characterized by the peroxidation damage of lipid molecular containing unsaturated fatty acid long chain on the cell membrane or organelle membrane after cellular deactivation restitution system, resulting in the cell membrane rupture. Ferroptosis is biochemically and morphologically distinct and disparate from other forms of regulated cell death. Recently, mounting studies have investigated the mechanism of ferroptosis, and numerous proteins play vital roles in regulating ferroptosis. With detailed studies, emerging evidence indicates that ferroptosis is found in multiple lung diseases, demonstrating that ferroptosis appears to be particularly important for lung diseases. The mounting interest in ferroptosis drugs specifically targeting the ferroptosis mechanism holds substantial therapeutic promise in lung diseases. The present review emphatically summarizes the functions and integrated molecular mechanisms of ferroptosis in various lung diseases, proposing that multiangle regulation of ferroptosis might be a promising strategy for the clinical treatment of lung diseases.

Disruption of rack1 suppresses SHH-type medulloblastoma formation in mice

Introduction

Medulloblastoma (MB) is a malignant pediatric brain tumor that arises in the cerebellar granular neurons. Sonic Hedgehog subtype of MB (SHH‐MB) is one of the major subtypes of MB in the clinic. However, the molecular mechanisms underlying MB tumorigenesis are still not fully understood.

Aims

Our previous work demonstrated that the receptor for activated C kinase 1 (Rack1) is essential for SHH signaling activation in granule neuron progenitors (GNPs) during cerebellar development. To investigate the potential role of Rack1 in MB development, human MB tissue array and SHH‐MB genetic mouse model were used to study the expression of function of Rack1 in MB pathogenesis.

Results

We found that the expression of Rack1 was significantly upregulated in the majority of human cerebellar MB tumors. Genetic ablation of Rack1 expression in SHH‐MB tumor mice could significantly inhibit MB proliferation, reduce the tumor size, and prolong the survival of tumor rescue mice. Interestingly, neither apoptosis nor autophagy levels were affected in Rack1‐deletion rescue mice compared to WT mice, but the expression of Gli1 and HDAC2 was significantly decreased suggesting the inactivation of SHH signaling pathway in rescue mice.

Conclusion

Our results demonstrated that Rack1 may serve as a potential candidate for the diagnostic marker and therapeutic target of MB, including SHH‐MB.

Role of Autophagy in Cadmium-Induced Hepatotoxicity and Liver Diseases

Cadmium (Cd) is a toxic pollutant that is associated with several severe human diseases. Cd can be easily absorbed in significant quantities from air contamination/industrial pollution, cigarette smoke, food, and water and primarily affects the liver, kidney, and lungs. Toxic effects of Cd include hepatotoxicity, nephrotoxicity, pulmonary toxicity, and the development of various human cancers. Cd is also involved in the development and progression of fatty liver diseases and hepatocellular carcinoma. Cd affects liver function via modulation of cell survival/proliferation, differentiation, and apoptosis. Moreover, Cd dysregulates hepatic autophagy, an endogenous catabolic process that detoxifies damaged cell organelles or dysfunctional cytosolic proteins through vacuole-mediated sequestration and lysosomal degradation. In this article, we review recent developments and findings regarding the role of Cd in the modulation of hepatotoxicity, autophagic function, and liver diseases at the molecular level.

Autophagy upregulation may explain inhibition of oral carcinoma in situ by photobiomodulation in vitro

There is currently no clear understanding on the pathways involved in the process of cell inhibition by photobiomodulation (PBM). The present study evaluated the influence of PBM on the expression of autophagy markers in vitro in an in situ model of oral carcinoma. Oral squamous cell carcinoma (Cal27) and stromal fibroblasts (FG) cultures were used. The independent variables were 'cell type' (FG and CAL27) 'culture condition' (monocultures or co-cultures) and PBM (placebo and 36 J/cm²). The cultures were irradiated from a red LED source for mRNA expression and protein expression analyses. The autophagy markers evaluated were Beclin-1, LC3B and p62 as well as adjuvant markers (BAX Bcl-2, VEGF, CD105, CD34, PRDX1, PRDX4 and GRP78). The Cal27 cells upregulated the autophagy markers upon exposure to PBM both at the mRNA and protein expression levels, providing evidence to explain malignant cell inhibition by PBM.

Anticancer Therapy with HDAC Inhibitors: Mechanism-Based Combination Strategies and Future Perspectives

The increasing knowledge of molecular drivers of tumorigenesis has fueled targeted cancer therapies based on specific inhibitors. Beyond "classic" oncogene inhibitors, epigenetic therapy is an emerging field. Epigenetic alterations can occur at any time during cancer progression, altering the structure of the chromatin, the accessibility for transcription factors and thus the transcription of genes. They rely on post-translational histone modifications, particularly the acetylation of histone lysine residues, and are determined by the inverse action of histone acetyltransferases (HATs) and histone deacetylases (HDACs). Importantly, HDACs are often aberrantly overexpressed, predominantly leading to the transcriptional repression of tumor suppressor genes. Thus, histone deacetylase inhibitors (HDACis) are powerful drugs, with some already approved for certain hematological cancers. Albeit HDACis show activity in solid tumors as well, further refinement and the development of novel drugs are needed. This review describes the capability of HDACis to influence various pathways and, based on this knowledge, gives a comprehensive overview of various preclinical and clinical studies on solid tumors. A particular focus is placed on strategies for achieving higher efficacy by combination therapies, including phosphoinositide 3-kinase (PI3K)-EGFR inhibitors and hormone- or immunotherapy. This also includes new bifunctional inhibitors as well as novel approaches for HDAC degradation via PROteolysis-TArgeting Chimeras (PROTACs).

Hydroxysafflor yellow A promotes apoptosis via blocking autophagic flux in liver cancer

Hydroxysafflor yellow A (HSYA) extracted from the herb Cathartics tinctorius L. negatively regulates liver cancer growth. However, the exact mechanism of HSYA action in liver cancer remains largely unknown. In this study, HSYA inhibited liver cancer cell growth in vivo and in vitro, evidenced by cell proliferation inhibition detected by CCK8, numerous apoptotic cells shown by flow cytometry assay, and expression of apoptosis-related proteins determined by western blot. Importantly, our data revealed that HSYA triggered autophagic response and autophagosome accumulation considering the increased levels of LC3II-conversion examined by western blot, LC3 puncta visualized by immunofluorescence, and expression of autophagy-related genes shown by quantitative real-time PCR. Furthermore, HSYA blocked the late-phase of autophagic flux via impairing the lysosomal acidification and downregulating LAMP1 expression, thereby likely inducing apoptosis. In addition, HSYA inhibited PI3K/AKT/mTOR signaling pathway. Taken together, as HSYA might inhibit cell proliferation and promote apoptosis via blocking autophagic flux in liver cancer, it may be considered a promising candidate for liver cancer therapy.

Modulation of Pancreatic Neuroendocrine Neoplastic Cell Fate by Autophagy-Mediated Death

INTRODUCTION

Autophagic cell death in cancer cells can be mediated by inhibition of deacetylases. Although extensive studies have focused on the autophagic process in cancer, little is known about the role of autophagy in degrading cytosolic and nuclear components of pancreatic neuroendocrine neoplastic (pNEN) cells leading to cell death, thus improving the therapy of patients affected by pNEN.

METHODS

2D and 3D human pNEN and pancreatic stellate cells were treated with panobinostat and bafilomycin. Autophagy markers were detected by RT-qPCR, immunofluorescence, and Western blot. Autophagosomes were detected by electron microscopy and their maturation by real-time fluorescence of LC3B stable transfected cells. ChIP was performed at the cAMP responsive element. Immunofluorescence was performed in murine pancreatic tissue.

RESULTS

We observed that pan-deacetylase inhibitor panobinostat treatment causes autophagic cell death in pNEN cells. We also found that although AMPK-α phosphorylation is counterbalanced by phosphorylated AKT, it is not capable to inhibiting autophagic cell death. However, the binding activity of the cAMP responsive element is prompted by panobinostat. Although autophagy inhibition prevented autophagosome synthesis, maturation, and cell death, panobinostat treatment induced the accumulation of mature autophagosomes in the cytosol and the nucleus, leading to disruption of the organelles, cellular digestion, and decay. Observation of autophagosome membrane proteins Beclin1 and LC3B aggregation in murine pancreatic islets indicates that autophagy restoration may also lead to autophagosome aggregation in murine insulinoma cells. A basal low expression of autophagy markers was detectable in patients affected by pNEN, and, interestingly, the expression of these markers was significantly lower in metastatic pNEN.

DISCUSSION/CONCLUSION

Our study highlights that the autophagy functional restoration and prolongation of this catabolic process, mediated by inhibition of deacetylase, is responsible for the reduction of pNEN cells. Prompting of autophagy cell death could be a promising strategy for the therapy of pNEN.

Hepigenetics: A Review of Epigenetic Modulators and Potential Therapies in Hepatocellular Carcinoma

Hepatocellular carcinoma is the fifth most common cancer worldwide and the second most lethal, following lung cancer. Currently applied therapeutic practices rely on surgical resection, chemotherapy and radiotherapy, or a combination thereof. These treatment options are associated with extreme adversities, and risk/benefit ratios do not always work in patients' favor. Anomalies of the epigenome lie at the epicenter of aberrant molecular mechanisms by which the disease develops and progresses. Modulation of these anomalous events poses a promising prospect for alternative treatment options, with an abundance of felicitous results reported in recent years. Herein, the most recent epigenetic modulators in hepatocellular carcinoma are recapitulated on.

A combination of AZD5363 and FH5363 induces lethal autophagy in transformed hepatocytes

Hepatocellular carcinoma (HCC) is one of the major causes of cancer-related death worldwide. High Akt activation and aberrant β-catenin expression contribute to HCC cell proliferation, stem cell generation, and metastasis. Several signaling pathway-specific inhibitors are in clinical trials and display different efficacies against HCC. In this study, we observed that a β-catenin inhibitor (FH535) displays antiproliferative effect on transformed human hepatocytes (THH). A combination treatment of these cells with FH535 and Akt inhibitor (AZD5363) exerted a stronger effect on cell death. Treatment of THH with AZD5363 and FH535 inhibited cell-cycle progression, enhanced autophagy marker protein expression, and autophagy-associated death, while FH535 treatment alone induced apoptosis. The use of chloroquine or z-VAD further verified these observations. Autophagy flux was evident from lowering marker proteins LAMP2, LAPTM4B, and autophagic protein expression by confocal microscopy using mCherry-EGFP-LC3 reporter construct. A combination treatment with AZD5363 and FH535 enhanced p53 expression, by modulating MDM2 activation; however, AZD5363 treatment alone restricted p53 to the nucleus by inhibiting dynamin-related protein activation. Nuclear p53 plays a crucial role for activation of autophagy by regulating the AMPK–mTOR-ULK1 pathway. Hep3B cells with null p53 did not modulate autophagy-dependent death from combination treatment. Together, our results strongly suggested that a combination treatment of Akt and β-catenin inhibitors exhibits efficient therapeutic potential for HCC.

BCL2L10/BECN1 modulates hepatoma cells autophagy by regulating PI3K/AKT signaling pathway

The aim of this study was to investigate BCL2L10 and BECN1 expression and their effect on autophagy in hepatocellular carcinoma (HCC). We found that BCL2L10 expression was low in hepatoma tissues and cells. Overexpression of BCL2L10 decreased the activity of hepatoma cells. To analyze autophagic flux, we monitored the formation of autophagic vesicles by fluorescence protein method. Autophagy-related protein LC3B-II was accumulated and P62 was decreased, which indicated that autophagy was induced by BECN1, while BCL2L10 could suppress this trend. Immunofluorescence assay showed that BCL2L10 and Beclin 1 were co-located in hepatoma cells. Immunoprecipitation showed that BCL2L10 could inhibit the autophagy of hepatoma cells by combining with Beclin 1. ELISA and co-immunoprecipitation suggested that the combination between BCL2L10 and Beclin 1 reduced the bond between Beclin 1 and PI3KC3. Based on Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, the PI3K/AKT signaling pathway was significantly upregulated in HCC. In conclusions, BCL2L10 had a low expression in HCC tissues and cells, which could release BECN1 to induce autophagy of hepatoma cells by downregulating PI3K/AKT signaling pathway.

Metabolism of Histone Deacetylase Proteins Opsonizes Tumor Cells to Checkpoint Inhibitory Immunotherapies

LC3-associated phagocytosis, a distinct form of autophagy, plays a key role in antigen presentation. Autophagy itself plays a central role in the regulation of cellular metabolism. Proteins that regulate autophagy include the AMPK which senses high levels of AMP, and mTOR, which integrates amino acid and fatty acid metabolism with autophagy. More recently, autophagy has been demonstrated to regulate tumor cell immunogenicity via the degradation of histone deacetylase proteins. Individual drugs and drug combinations that activate the ATM-AMPK pathway and inactivate mTOR, cause autophagosome formation. The maturation of autophagosomes into autolysosomes causes the autophagic degradation of histone deacetylase proteins who regulate the transcription of PD-L1, Class I MHCA, ODC and IDO1. Indeed, drug combinations that do not contain an HDAC inhibitor can nevertheless act as de facto HDAC inhibitors, via autophagic degradation of HDAC proteins. Such drug combinations simultaneously kill tumor cells via immunogenic autophagy and in parallel opsonize tumor cells to checkpoint inhibitor immunotherapies via reduced expression of PD-L1, ODC and IDO1, and increased expression of Class I MHCA.

Harmonized Autophagy Versus Full-Fledged Hepatitis B Virus: Victorious or Defeated

Autophagy is a finely tuned process in the regulation of innate immunity to avoid excessive inflammatory responses and inflammasome signaling. In contrast, the results of recent studies have shown that autophagy may disease-dependently contribute to the pathogenesis of liver diseases, such as fibrosis, cirrhosis, and hepatocellular carcinoma (HCC) during hepatitis B virus (HBV) infection. HBV has learned to subvert the cell's autophagic machinery to promote its replication. Given the great impact of the autophagy mechanism on the HBV infection and HCC, recognizing these factors may be offered new hope for human intervention and treatment of chronic HBV. This review focuses on recent findings viewing the dual role of autophagy plays in the pathogenesis of HBV infected hepatocytes.

Hepatocellular carcinoma: Therapeutic advances in signaling, epigenetic and immune targets

Hepatocellular carcinoma (HCC) remains a global medical burden with rising incidence due to chronic viral hepatitis and non-alcoholic fatty liver diseases. Treatment of advanced disease stages is still unsatisfying. Besides first and second generation tyrosine kinase inhibitors, immune checkpoint inhibitors have become central for the treatment of HCC. New modalities like epigenetic therapy using histone deacetylase inhibitors (HDACi) and cell therapy approaches with chimeric antigen receptor T cells (CAR-T cells) are currently under investigation in clinical trials. Development of such novel drugs is closely linked to the availability and improvement of novel preclinical and animal models and the identification of predictive biomarkers. The current status of treatment options for advanced HCC, emerging novel therapeutic approaches and different preclinical models for HCC drug discovery and development are reviewed here.

Sodium butyrate induces autophagic apoptosis of nasopharyngeal carcinoma cells by inhibiting AKT/mTOR signaling

Previously, we confirmed the anti-tumor effects of sodium butyrate (NaBu) in nasopharyngeal carcinoma (NPC). However, its molecular mechanisms have not be fully elucidated. In this study, we studied the effects of NaBu on autophagy and explored the relation between NaBu associated autophagy and apoptosis in NPC cells. EGFP-LC3 plasmids were introduced into NPC cells to observed the effects of NaBu on autophagy flux with or without chloroquine (CQ) addition. Autophagy markers were also detected by Western blot. Under NaBu treatment, autophagy and apoptosis markers were detected simultaneously at different time. Then, to explore the roles of autophagy in NaBu induced apoptosis, the effects of autophagy inhibition, via specific inhibitor treatment or key gene knockdown, were analyzed. At last, the upstream signaling and its roles in NaBu induced autophagy and apoptosis were also analyzed. Increased LC3 dots and LC3-II accumulation indicated that NaBu can promote autophagy flux in NPC cells. LC3-II accumulation was earlier than cleaved PARP increment suggesting autophagy activation is prior to apoptosis activation, which was validated by flow cytometry mediated apoptosis analysis. Moreover, autophagy inhibition, achieved by 3-MA treatment or BECN1 knockdown, can antagonize NaBu induced apoptosis reflecting by re-deregulated cPARP and apoptotic rates. Furthermore, NaBu treatment inhibited the AKT/mTOR axis indicated by deregulated p-AKT(S473) and p-mTOR(S2448) and ectopic AKT expression both suppressed NaBu induced autophagy and apoptosis. At last, Western blot showed that HDAC6 dependent EGFR deregulation may account for the NaBu associated AKT/mTOR inhibition. NaBu can induce autophagic apoptosis via suppressing AKT/mTOR axis in NPC cells. Our results suggest that combination of autophagy inhibitors and deacetylase inhibitors may not be recommended in NPC clinical treatment.

Diverse Functions of Autophagy in Liver Physiology and Liver Diseases

Autophagy is a catabolic process by which eukaryotic cells eliminate cytosolic materials through vacuole-mediated sequestration and subsequent delivery to lysosomes for degradation, thus maintaining cellular homeostasis and the integrity of organelles. Autophagy has emerged as playing a critical role in the regulation of liver physiology and the balancing of liver metabolism. Conversely, numerous recent studies have indicated that autophagy may disease-dependently participate in the pathogenesis of liver diseases, such as liver hepatitis, steatosis, fibrosis, cirrhosis, and hepatocellular carcinoma. This review summarizes the current knowledge on the functions of autophagy in hepatic metabolism and the contribution of autophagy to the pathophysiology of liver-related diseases. Moreover, the impacts of autophagy modulation on the amelioration of the development and progression of liver diseases are also discussed.

Panobinostat mediated cell death: a novel therapeutic approach for osteosarcoma

Osteosarcoma is an aggressive cancer with a poor long term prognosis. Neo-adjuvant poly-chemotherapy followed by surgical resection remains the standard treatment, which is restricted by multi-drug resistance. If first-line therapy fails, disease control and patient survival rate drop dramatically. We aimed to identify alternative apoptotic mechanisms induced by the histone deacetylase inhibitor panobinostat in osteosarcoma cells. Saos-2, MG63 and U2-OS osteosarcoma cell lines, the immortalized human osteoblast line hFOB and the mouse embryo osteoblasts (MC3T3-E1) were treated with panobinostat. Real time viability and FACS confirmed the cytotoxicity of panobinostat. Cell stress/death related factors were analysed by RT-qPCR and western blot. Cell morphology was assessed by electron microscopy. 10 nM panobinostat caused cell viability arrest and death in all osteosarcoma and osteoblast cells. P21 up-regulation was observed in osteosarcoma cells, while over-expression of p73 was restricted to Saos-2 (TP53^-/-). Survivin and Bcl-2 were suppressed by panobinostat. Endoplasmic reticulum (ER) stress markers BiP, CHOP, ATF4 and ATF6 were induced in osteosarcoma cells. The un-spliced Xbp was no further detectable after treatment. Autophagy players Beclin1, Map1LC3B and UVRAG transcripts over-expressed after 6 hours. Protein levels of Beclin1, Map1LC3B and p62 were up-regulated at 72 hours. DRAM1 was stable. Electron micrographs revealed the fragmentation and the disappearance of the ER and the statistically significant increase of autophagosome vesiculation after treatment. Panobinostat showed a synergistic suppression of survival and promotion of cell death in osteosarcoma cells. Panobinostat offers new perspectives for the treatment of osteosarcoma and other malignant bone tumours.

Modification of Epigenetic Histone Acetylation in Hepatocellular Carcinoma

Cells respond to various environmental factors such as nutrients, food intake, and drugs or toxins by undergoing dynamic epigenetic changes. An imbalance in dynamic epigenetic changes is one of the major causes of disease, oncogenic activities, and immunosuppressive effects. The aryl hydrocarbon receptor (AHR) is a unique cellular chemical sensor present in most organs, and its dysregulation has been demonstrated in multiple stages of tumor progression in humans and experimental models; however, the effects of the pathogenic mechanisms of AHR on epigenetic regulation remain unclear. Apart from proto-oncogene activation, epigenetic repressions of tumor suppressor genes are involved in tumor initiation, procession, and metastasis. Reverse epigenetic repression of the tumor suppressor genes by epigenetic enzyme activity inhibition and epigenetic enzyme level manipulation is a potential path for tumor therapy. Current evidence and our recent work on deacetylation of histones on tumor-suppressive genes suggest that histone deacetylase (HDAC) is involved in tumor formation and progression, and treating hepatocellular carcinoma with HDAC inhibitors can, at least partially, repress tumor proliferation and transformation by recusing the expression of tumor-suppressive genes such as TP53 and RB1.

Targeting autophagy in liver cancer

Autophagy is a catabolic cellular process conserved in animals. It is characterized by the main role of recycling all the non-functional products of the cells. Once, autophagy players detect non-functioning sub-cellular organelles and proteins, they start the so-called nucleation process. The organelles will be surrounded by a double membrane vesicle mainly constituted by endoplasmic reticulum (ER) membrane and autophagy proteins, e.g., MAP1LC3B, Beclin-1, VPS34, Unc-51 like autophagy activating kinase (ULK1) and ubiquitination-related proteins. Then the autophagic membrane will go through an elongation phase involving additional autophagy players. Once the autophagic vesicle is complete, the sub-cellular organelles will be isolated from the rest of the cytosol and driven to the final fusion with lysosomes. Here, the digestion process will end. Alteration and or impairment of autophagy have been shown to be correlated with development of diseases affecting the central nervous system, e.g., Alzheimer and other neurodegenerative diseases. Nonetheless, autophagy defect is responsible for tumorigenesis in blood and solid malignancies, in particular liver cancer. Malignancies of the liver are determined by several genetics and epigenetics mechanisms triggering the up-regulation of survival mechanisms and resistance to cell death. Furthermore, liver cancer could result from pathologic conditions like cirrhosis and fibrosis related to virus infection, aflatoxin, alcohol consumption and high fat diet together with insulin resistance. The role exerted by autophagy in the pathogenesis of the liver and tumor development has been evidenced in recent years. The alteration of autophagy assumes a fundamental role for liver tumorigenesis determining an accumulation of non-functional proteins and organelles that trigger oxidative stress leading to genotoxic stress and gene alterations. Furthermore, the absence of this degradation mechanism could prompt the cells to alter their metabolic status and turn into malignant cells. Interestingly, the heterozygous loss of function of Beclin-1 is able to trigger liver tumorigenesis or even the simple accumulation of proteins caused by the block of the final autolysosome fusion and degradation process is responsible for liver cancer development. This review highlights the importance of targeting the autophagy process in liver cancer in order to restore its function and to promote autophagy-mediated cell demise.

Expression of hsa-let-7b-5p, hsa-let-7f-5p, and hsa-miR-222-3p and their putative targets HMGA2 and CDKN1B in typical and atypical carcinoid tumors of the lung

Typical and atypical carcinoid tumors belong to the neuroendocrine lung tumors. They have low recurrence and proliferation rate, lymph node, and distant metastases. Nevertheless, these tumors have shown a more aggressive behavior. In the last years, microRNAs were screened as new tumor markers for their potential diagnostic and therapeutic relevance. The expression of hsa-let-7b-5p, hsa-let-7f-5p, hsa-miR-222-3p, and their targets HMGA2 (high-mobility group A2) and CDKN1B (cyclin-dependent kynase inhibitor 1B, p27^kip1) was evaluated in this rare small group of patients. We analyzed the clinical data of all typical and atypical carcinoid tumors of patients who underwent surgical operation at Marburg University Hospital (n = 18) from 2000. Quantitative reverse transcription polymerase chain reaction was performed in formalin-fixed paraffin-embedded tumor tissue versus four tumor-free lung tissue samples. HMGA2 was stable or downregulated; only one patient showed a significant overexpression. CDKN1B showed a significant overexpression or a stable level; it was downregulated in two samples only. Hsa-miR-222-3p resulted almost stable or overexpressed except for two samples (significantly downregulated). Hsa-let-7f-5p was stable or overexpressed in the majority of analyzed samples, whereas hsa-let-7b-5p was significantly downregulated. HMGA2 and CDKN1B are differently expressed between atypical and typical carcinoid tumors, thus representing valid biomarkers for the classification of the two tumor groups. Hsa-let-7f-5p and HMGA2 are inversely correlated. Hsa-miR-222-3p does not correlate with its predicted target CDKN1B.

Mevastatin blockade of autolysosome maturation stimulates LBH589-induced cell death in triple-negative breast cancer cells

Histone deacetylase inhibitors (HDACi) are promising anti-cancer agents, and combining a HDACi with other agents is an attractive therapeutic strategy in solid tumors. We report here that mevastatin increases HDACi LBH589-induced cell death in triple-negative breast cancer (TNBC) cells. Combination treatment inhibited autophagic flux by preventing Vps34/Beclin 1 complex formation and downregulating prenylated Rab7, an active form of the small GTPase necessary for autophagosome-lysosome fusion. This means that co-treatment with mevastatin and LBH589 activated LKB1/AMPK signaling and subsequently inhibited mTOR. Co-treatment also led to cell cycle arrest in G2/M phase and induced corresponding expression changes of proteins regulating the cell cycle. Co-treatment also increased apoptosis both in vitro and in vivo, and reduced tumor volumes in xenografted mice. Our results indicate that disruption of autophagosome-lysosome fusion likely underlies mevastatin-LBH589 synergistic anticancer effects. This study confirms the synergistic efficacy of, and demonstrates a potential therapeutic role for mevastatin plus LBH589 in targeting aggressive TNBC, and presents a novel therapeutic strategy for further clinical study. Further screening for novel autophagy modulators could be an efficient approach to enhance HDACi-induced cell death in solid tumors.

Gene signature associated with benign neurofibroma transformation to malignant peripheral nerve sheath tumors

Benign neurofibromas, the main phenotypic manifestations of the rare neurological disorder neurofibromatosis type 1, degenerate to malignant tumors associated to poor prognosis in about 10% of patients. Despite efforts in the field of (epi)genomics, the lack of prognostic biomarkers with which to predict disease evolution frustrates the adoption of appropriate early therapeutic measures. To identify potential biomarkers of malignant neurofibroma transformation, we integrated four human experimental studies and one for mouse, using a gene score-based meta-analysis method, from which we obtained a score-ranked signature of 579 genes. Genes with the highest absolute scores were classified as promising disease biomarkers. By grouping genes with similar neurofibromatosis-related profiles, we derived panels of potential biomarkers. The addition of promoter methylation data to gene profiles indicated a panel of genes probably silenced by hypermethylation. To identify possible therapeutic treatments, we used the gene signature to query drug expression databases. Trichostatin A and other histone deacetylase inhibitors, as well as cantharidin and tamoxifen, were retrieved as putative therapeutic means to reverse the aberrant regulation that drives to malignant cell proliferation and metastasis. This in silico prediction corroborated reported experimental results that suggested the inclusion of these compounds in clinical trials. This experimental validation supported the suitability of the meta-analysis method used to integrate several sources of public genomic information, and the reliability of the gene signature associated to the malignant evolution of neurofibromas to generate working hypotheses for prognostic and drug-responsive biomarkers or therapeutic measures, thus showing the potential of this in silico approach for biomarker discovery.

The interplay between autophagy and tumorigenesis: exploiting autophagy as a means of anticancer therapy

In wild-type cells, autophagy represents a tumour-suppressor mechanism, and dysfunction of the autophagy machinery increases genomic instability, DNA damage, oxidative stress and stem/progenitor expansion, which are events associated with cancer onset. Autophagy occurs at a basal level in all cells depending on cell type and cellular microenvironment. However, the role of autophagy in cancer is diverse and can promote different outcomes even in a single tumour. For example, in hypoxic tumour regions, autophagy emerges as a protective mechanism and allows cancer cell survival. By contrast, in cancer cells surrounding the tumour mass, the induction of autophagy by radio- or chemotherapy promotes cell death and significantly reduces the tumour mass. Importantly, inhibition of autophagy compromises tumorigenesis by mechanisms that are not entirely understood. The aim of this review is to explain the apparently contradictory role of autophagy as a mechanism that both promotes and inhibits tumorigenesis using different models. The induction/inhibition of autophagy as a mechanism for cancer treatment is also discussed.

Lycorine Induces Apoptosis of A549 Cells via AMPK-Mammalian Target of Rapamycin (mTOR)-S6K Signaling Pathway

BACKGROUND This study was designed to investigate the effect of lycorine (LY) on the AMPK-mTOR-S6K signaling pathway and to clarify its role in autophagy and apoptosis. MATERIAL AND METHODS Various concentrations of LY were used to treat non-small cell lung carcinoma A549 cells. The MTT assay was used to measure cell viability and acridine orange staining was used to detect cell morphology changes. Western blot analysis was used to test the effect of LY on the expression levels of LC3, caspase 3, and other proteins involved in the AMPK-mTOR-S6K signaling pathway. RESULTS The half maximal inhibitory concentration (IC50) of LY after 24-h treatment was 8.5 μM, with stronger inhibitory effect of 24-h LY treatment over 12-h LY treatment. Morphological observation showed that lower doses (4 μM and 8 μM) of LY treatment induced A549 cell death mainly caused by autophagy, whereas the higher dose (16 μM) of LY treatment induced A549 cell death, mainly caused by apoptosis. Furthermore, 8 μM LY caused the highest conversion of LC3-II from LC3-I. All LY treatments activated caspase-3. LY treatment also promoted AMPK phosphorylation (Thr172) and inhibited the phosphorylation of mTOR and S6K. CONCLUSIONS LY induced apoptosis of A549 cells by regulating the AMPK-mTOR-S6K signaling pathway. Lower levels (4~8 μM) of LY-induced autophagy contributed to LY-induced apoptosis.

Vitexin suppresses autophagy to induce apoptosis in hepatocellular carcinoma via activation of the JNK signaling pathway

Vitexin, a flavonoids compound, is known to exhibit broad anti-oxidative, anti-inflammatory, analgesic, and antitumor activity in many cancer xenograft models and cell lines. The purpose of this study was to investigate the antitumor effects and underlying mechanisms of vitexin on hepatocellular carcinoma. In this study, we found that vitexin suppressed the viability of HCC cell lines (SK-Hep1 and Hepa1-6 cells) significantly. Vitexin showed cytotoxic effects against HCC cell lines in vitro by inducing apoptosis and inhibiting autophagy. Vitexin induced apoptosis in a concentration-dependent manner, and caused up-regulations of Caspase-3, Cleave Caspase-3, and a down-regulation of Bcl-2. The expression of autophagy-related protein LC3 II was significantly decreased after vitexin treatment. Moreover, western blot analysis presented that vitexin markedly up-regulated the levels of p-JNK and down-regulated the levels of p-Erk1/2 in SK-Hep1 cells and Hepa1-6 cells. Cotreatment with JNK inhibitor SP600125, we demonstrated that apoptosis induced by vitexin was suppressed, while the inhibition of autophagy by vitexin was reversed. The results of colony formation assay and mouse model confirmed the growth inhibition role of vitexin on HCC in vitro and in vivo. In conclusion, vitexin inhibits HCC growth by way of apoptosis induction and autophagy suppression, both of which are through JNK MAPK pathway. Therefore, vitexin could be regarded as a potent therapeutic agent for the treatment of HCC.