Dysfunction of degradation machineries causes cancers, including hepatocellular carcinoma (HCC). Overexpression of cyclin D1 in HCC has been reported. We previously reported that autophagy ...preferentially recruits and degrades the oncogenic microRNA (miR)‐224 to prevent HCC. Therefore, in the present study, we attempted to clarify whether cyclin D1 is another oncogenic factor selectively regulated by autophagy in HCC tumorigenesis. Initially, we found an inverse correlation between low autophagic activity and high cyclin D1 expression in tumors of 147 HCC patients and three murine models, and these results taken together revealed a correlation with poor overall survival of HCC patients, indicating the importance of these two events in HCC development. We found that increased autophagic activity leads to cyclin D1 ubiquitination and selective recruitment to the autophagosome (AP) mediated by a specific receptor, sequestosome 1 (SQSTM1), followed by fusion with lysosome and degradation. Autophagy‐selective degradation of ubiquitinated cyclin D1 through SQSTM1 was confirmed using cyclin D1/ubiquitin binding site (K33‐238R) and phosphorylation site (T286A) mutants, lentivirus‐mediated silencing autophagy‐related 5 (ATG5), autophagy‐related 7 (ATG7), and Sqstm1 knockout cells. Functional studies revealed that autophagy‐selective degradation of cyclin D1 plays suppressive roles in cell proliferation, colony, and liver tumor formation. Notably, an increase of autophagic activity by pharmacological inducers (amiodarone and rapamycin) significantly suppressed tumor growth in both the orthotopic liver tumor and subcutaneous tumor xenograft models. Our findings provide evidence of the underlying mechanism involved in the regulation of cyclin D1 by selective autophagy to prevent tumor formation. Conclusion: Taken together, our data demonstrate that autophagic degradation machinery and the cell‐cycle regulator, cyclin D1, are linked to HCC tumorigenesis. We believe these findings may be of value in the development of alternative therapeutics for HCC patients. (Hepatology 2018;68:141‐154).
Dengue virus (DENV) utilizes the endoplasmic reticulum (ER) for replication and assembling. Accumulation of unfolded proteins in the ER lumen leads to ER stress and unfolded protein response (UPR). ...Three branches of UPRs temporally modulated DENV infection. Moreover, ER stress can also induce autophagy. DENV infection induces autophagy which plays a promotive role in viral replication has been reported. However, the role of ER stress in DENV-induced autophagy, viral titer, and pathogenesis remain unclear. Here, we reveal that ER stress and its downstream UPRs are indispensable for DENV-induced autophagy in various human cells. We demonstrate that PERK-eIF2α and IRE1α-JNK signaling pathways increased autophagy and viral load after DENV infection. However, ATF6-related pathway showed no effect on autophagy and viral replication. IRE1α-JNK downstream molecule Bcl-2 was phosphorylated by activated JNK and dissociated from Beclin 1, which playing a critical role in autophagy activation. These findings were confirmed as decreased viral titer, attenuated disease symptoms, and prolonged survival rate in the presence of JNK inhibitor in vivo. In summary, we are the first to reveal that DENV2-induced ER stress increases autophagy activity, DENV replication, and pathogenesis through two UPR signaling pathways both in vitro and in vivo.
Overexpressed CCND1 (cyclin D1) is associated with hepatocellular carcinoma (HCC) and we used 147 tumor tissue samples from HCC patients and 3 murine models to reveal an inverse correlation between ...low autophagic activity and high CCND1 expression. These 2 phenomena in combination correlated with poor overall survival in HCC patients. Mechanistic analysis showed that activated autophagy triggered CCND1 ubiquitination followed by SQSTM1 (sequestosome 1)-mediated selective phagophore recruitment, autophagosome formation, fusion with a lysosome, and degradation. Functional studies revealed that autophagy-selective degradation of CCND1 suppresses DNA synthesis, cell proliferation, and colony, and liver tumor formation by arresting the cell cycle at the G
1
phase. Most importantly, diverse pharmacological inducers (rapamycin and amiodarone) effectively suppress tumor growth in orthotopic liver tumor and subcutaneous tumor xenograft models. In conclusion, we have demonstrated a link between degradative autophagy and the cell cycle regulator CCND1, and have discovered the underlying mechanism by which the autophagic degradation machinery regulates the turnover of the cell-cycle regulator CCND1, which in turn affects HCC tumorigenesis.
Abbreviations: CCDN1: cyclin D1; HBV: hepatitis B virus; HCC: hepatocellular carcinoma; HCV: hepatitis C virus; SQSTM1: sequestosome 1
Formosanin C (FC) is a natural compound extracted from Paris formosana Hayata with anticancer activity. FC induces both autophagy and apoptosis in human lung cancer cells. FC‐induced depolarization ...of mitochondrial membrane potential (MMP) may trigger mitophagy. In this study, we clarified the effect of FC on autophagy, mitophagy, and the role of autophagy in FC‐related cell death and motility. We found FC caused the continuous increase of LC3 II (representing autophagosomes) from 24 to 72 h without degradation after treatment of lung and colon cancer cells, indicating that FC blocks autophagic progression. In addition, we confirmed that FC also induces early stage autophagic activity. Altogether, FC is not only an inducer but also a blocker of autophagy progression. Moreover, FC increased MMP accompanied by overexpression of COX IV (mitochondria marker) and phosphorylated Parkin (p‐Parkin, mitophagy marker) in lung cancer cells, but no colocalization of LC3 with COX IV or p‐Parkin was detected under confocal microscopy. Moreover, FC could not block CCCP (mitophagy inducer)‐induced mitophagy. These results imply that FC disrupts mitochondria dynamics in the treated cells, and the underlying mechanism deserves further exploration. Functional analysis reveals that FC suppresses cell proliferation and motility through apoptosis and EMT‐related pathway, respectively. In conclusion, FC acts as an inducer as well as a blocker of autophagy that results in cancer cell apoptosis and decreased motility. Our findings shed the light on the development of combined therapy with FC and clinical anticancer drugs for cancer treatment.
In hepatocellular carcinoma (HCC), dysregulated expression of microRNA‐224 (miR‐224) and impaired autophagy have been reported separately. However, the relationship between them has not been ...explored. In this study we determined that autophagy is down‐regulated and inversely correlated with miR‐224 expression in hepatitis B virus (HBV)‐associated HCC patient specimens. These results were confirmed in liver tumors of HBV X gene transgenic mice. Furthermore, miR‐224 was preferentially recruited and degraded during autophagic progression demonstrated by real‐time polymerase chain reaction and miRNA in situ hybridization electron microscopy after extraction of autophagosomes. Our in vitro study demonstrated that miR‐224 played an oncogenic role in hepatoma cell migration and tumor formation through silencing its target gene Smad4. In HCC patients, the expression of low‐Atg5, high‐miR‐224, and low‐Smad4 showed significant correlation with HBV infection and a poor overall survival rate. Autophagy‐mediated miR‐224 degradation and liver tumor suppression were further confirmed by the autophagy inducer amiodarone and miR‐224 antagonist using an orthotopic SD rat model. Conclusion: A noncanonical pathway links autophagy, miR‐224, Smad4, and HBV‐associated HCC. These findings open a new avenue for the treatment of HCC. (Hepatology 2014;59:505–517)
Abstract
Background
Rab37-mediated exocytosis of tissue inhibitor of metalloproteinase 1 (TIMP1), an inflammatory cytokine, under serum-depleted conditions which leads to suppression of lung cancer ...cell metastasis has been reported. Starvation is also a stimulus of autophagic activity. Herein, we reveal that starvation activates Rab37 and induces autophagy.
Methods
We used an overexpression/knockdown system to determine the relationship between autophagy and Rab37 in vitro and in vivo. The autophagy activity was detected by immunoblotting, transmission electron microscope, autophagosome purification, and immunofluorescence under the confocal microscope. Lung-to-lung metastasis mouse model was used to clarify the role of autophagy and Rab37 in lung cancer. Clinical lung cancer patient specimens and an online big database were analyzed.
Results
Initially, we demonstrated that active-form Rab37 increased LC3-II protein level (the marker of autophagosome) and TIMP1 secretion. Accordingly, silencing of Rab37 gene expression alleviated Rab37 and LC3-II levels as well as TIMP1 secretion, and induction of autophagy could not increase TIMP1 exocytosis under such conditions. Moreover, silencing the
Atg5
or
Atg7
gene of lung cancer cells harboring active-mutant Rab37 (Q89L) led to decreased autophagy activity and TIMP1 secretion. In the lung-to-lung metastasis mouse model, increased TIMP1 expression accompanied by amiodarone-induced autophagy led to decreased tumor nodules and cancer cell metastasis. These phenomena were reversed by silencing the
Atg5
or
Atg7
gene. Notably, increasing autophagy activity alone showed no effect on TIMP1 secretion under either Rab37 or Sec22b silencing conditions. We further detected colocalization of LC3 with either Rab37 or TIMP1, identified Rab37 and Sec22b proteins in the purified autophagosomes of the lung cancer cells harboring the active-form Rab37 gene, and confirmed that these proteins are involved in the secretion of TIMP1. We reveal that autophagic activity was significantly lower in the tumors compared to the non-tumor parts and was associated with the overall lung cancer patient survival rate.
Conclusions
We are the first to report that autophagy plays a promoting role in TIMP1 secretion and metastasis in a Rab37-dependent manner in lung cancer cells and the lung-to-lung mouse model.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
7.
Autophagy and metabolism Lin, Pei‐Wen; Chu, Man‐Ling; Liu, Hsiao‐Sheng
The Kaohsiung journal of medical sciences,
January 2021, 2021-Jan, 2021-01-00, 20210101, Letnik:
37, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Metabolism consists of diverse life‐sustaining chemical reactions in living organisms. Autophagy is a highly conservative process that responds to various internal and external stresses. Both ...processes utilize surrounding resources to provide energy and nutrients for the cell. Autophagy progression may proceed to the degradative or secretory pathway determined by Rab family proteins. The former is a degradative and lysosome‐dependent catabolic process that produces energy and provides nutrients for the synthesis of essential proteins. The degradative pathway also balances the energy source of the cell and regulates tissue homeostasis. The latter is a newly discovered pathway in which the autophagosome is fused with the plasma membrane. Secretory autophagy participates in diverse functions and diseases ranging from the spread of viral particles to cancer and neurodegenerative diseases. Aberrant metabolism in the body causes various metabolic syndromes. This review explores the relationships among autophagy, metabolism, and related diseases.
Background: Diffuse large B-cell lymphoma (DLBCL) is a malignant lymphoid tumor disease that is characterized by heterogeneity, but current treatment does not benefit all patients, which highlights ...the need to identify oncogenic genes and appropriate drugs. G9a is a histone methyltransferase that catalyzes histone H3 lysine 9 (H3K9) methylation to regulate gene function and expression in various cancers. Methods: TCGA and GTEx data were analyzed using the GEPIA2 platform. Cell viability under drug treatment was assessed using Alamar Blue reagent; the interaction between G9a and niclosamide was assessed using molecular docking analysis; mRNA and protein expression were quantified in DLBCL cell lines. Finally, G9a expression was quantified in 39 DLBCL patient samples. Results: The TCGA database analysis revealed higher G9a mRNA expression in DLBCL compared to normal tissues. Niclosamide inhibited DLBCL cell line proliferation in a time- and dose-dependent manner, reducing G9a expression and increasing p62, BECN1, and LC3 gene expression by autophagy pathway regulation. There was a correlation between G9a expression in DLBCL samples and clinical data, showing that advanced cancer stages exhibited a higher proportion of G9a-expressing cells. Conclusion: G9a overexpression is associated with tumor progression in DLBCL. Niclosamide effectively inhibits DLBCL growth by reducing G9a expression via the cellular autophagy pathway; therefore, G9a is a potential molecular target for the development of therapeutic strategies for DLBCL.
Dengue virus (DENV) is the most common mosquito-borne flavivirus; it can either cause mild dengue fever or the more severe dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS). One of the ...characteristic features of DHF/DSS is vascular leakage; although DENV nonstructural protein 1 (NS1) has been proved to induce vascular leakage after binding to Toll-like receptor 4, the down-stream mechanism has not yet been fully understood. In the sera of DENV-infected patients, the concentrations of DENV NS1 and inflammatory cytokine macrophage migration inhibitory factor (MIF) are positively correlated with disease severity, but whether DENV NS1 induces vascular leakage through MIF secretion remains unknown. We demonstrated that recombinant NS1 induced vascular leakage and MIF secretion both in human endothelial cell line HMEC-1 and in mice. Furthermore, these phenomena were inhibited in the presence of anti-NS1 antibodies both in vitro and in vivo. DENV NS1 also induced LC3-I to LC3-II conversion and p62 degradation in endothelial cell line, which indicated the formation of autophagy. To clarify whether MIF or autophagy mediated DENV NS1-induced vascular leakage, various inhibitors were applied. The results showed that DENV NS1-induced vascular leakage and VE-cadherin disarray were blocked in the presence of MIF inhibitors, anti-MIF-antibodies or autophagy inhibitors. An Atg5 knockdown clone further confirmed that autophagy formation of endothelial cells was required in NS1-induced vascular leakage. Furthermore, DENV NS1-induced LC3 puncta were also decreased in the presence of MIF inhibitors, indicating that MIF mediated DENV NS1-induced autophagy. Taken together, the results suggest a potential mechanism of DENV-induced vascular leakage and provide possible therapeutic targets against DHF/DSS.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Colorectal cancer (CRC) is a highly prevalent cancer type with limited targeted therapies available and 5-year survival rate, particularly for late-stage patients. There have been numerous attempts ...to repurpose drugs to tackle this problem. It has been reported that autophagy inducers could augment the effect of certain chemotherapeutic agents by enhancing immunogenic cell death (ICD).
In this study, we employed bioinformatics tools to identify thioridazine (THD), an antipsychotic drug, and found that it could induce autophagy and ICD in CRC. Then in vitro and in vivo experiments were performed to further elucidate the molecular mechanism of THD in CRC.
THD was found to induce endoplasmic reticulum (ER) stress in CRC cells by activating the eIF2α/ATF4/CHOP axis and facilitating the accumulation of secretory autophagosomes, leading to ICD. In addition, THD showed a remarkable ICD-activating effect when combined with oxaliplatin (OXA) to prevent tumor progression in the mouse model.
Together, our findings suggest that the repurposed function of THD in inhibiting CRC involves the upregulation of autophagosomes and ER stress signals, promoting the release of ICD markers, and providing a potential candidate to enhance the clinical outcome for CRC treatment. Video Abstract.
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