SIRT1 is a regulator of autophagy: Implications in gastric cancer progression and treatment

Mechanism of salidroside regulating autophagy based on network pharmacology and molecular docking

Salidroside is a natural product of phenols with a wide range of pharmacological functions, but whether it plays a role in regulating autophagy is unclear. We systematically investigated the regulatory effect and molecular mechanism of salidroside on autophagy through network pharmacology, which provided a theoretical basis for subsequent experimental research. First, the target genes of salidroside were obtained using the Chinese Medicine System Pharmacology Database and Analysis Platform, and the target genes were converted into standardized gene names using the Uniprot website. At the same time, autophagy-related genes were collected from GeneCards, and preliminary handling of data to obtain intersecting genes. Then, the String website was used to construct a protein-protein interaction network, and to perform the Gene Ontology functional annotation and Kyoto Encyclopedia of Genes and Genomes pathway analysis. To observe the specific molecular mechanism by which salidroside regulates autophagy, we constructed a drug component-target genes-autophagy network. Finally, we performed molecular docking to verify the possible binding conformation between salidroside and the candidate target. By searching the database and analyzing the data, we found that 113 target genes in salidroside interact with autophagy. Salidroside regulate autophagy in relation to a number of important oncogenes and signaling pathways. Molecular docking confirmed that salidroside has high affinity with mTOR, SIRT1, and AKT1. Through network pharmacology combined with molecular docking-validated research methods, we revealed the underlying mechanism of salidroside regulation of autophagy. This study not only provides new systematic insights into the underlying mechanism of salidroside in autophagy, but also provides new ideas for network approaches for autophagy-related research.

Expression of LC3A, LC3B and p62/SQSTM1 autophagy proteins in hepatocellular carcinoma (HCC) tissues and the predicted microRNAs involved in the autophagy-related pathway

BACKGROUND

Autophagy plays multifaceted roles in regulating hepatocellular carcinoma (HCC) and the mechanisms involved are under-explored. Regulatory microRNAs (miRNAs) have been reported to target autophagy proteins but their roles in HCC is not well studied. Using HCC patient tissues, this study aims to investigate the association of autophagy with several clinicopathological parameters as well as identifying the autophagy-related miRNAs and the possible pathways.

METHODS AND RESULTS

Autophagy level in the HCC patient-derived cancer and non-cancer tissues was determined by immunohistochemistry (IHC) targeting SQSTM1, LC3A and LC3B proteins. Significance tests of clinicopathological variables were tested using the Fisher's exact or Chi-square tests. Gene and miRNA expression assays were carried out and analyzed using Nanostring platform and software followed by validation of other online bioinformatics tools, namely String and miRabel. Autophagy expression was significantly higher in cancerous tissues compared to adjacent non-cancer tissues. High LC3B expression was associated with advanced tumor histology grade and tumor location. Nanostring gene expression analysis revealed that SQSTM1, PARP1 and ATG9A genes were upregulated in HCC tissues compared to non-cancer tissues while SIRT1 gene was downregulated. These genes are closely related to an autophagy pathway in HCC. Further, using miRabel tool, three downregulated miRNAs (hsa-miR-16b-5p, hsa-miR-34a-5p, and hsa-miR-660-5p) and one upregulated miRNA (hsa-miR-539-5p) were found to closely interact with the abovementioned autophagy-related genes. We then mapped out the possible pathway involving the genes and miRNAs in HCC tissues.

CONCLUSIONS

We conclude that autophagy events are more active in HCC tissues compared to the adjacent non-cancer tissues. We also reported the possible role of several miRNAs in regulating autophagy-related genes in the autophagy pathway in HCC. This may contribute to the development of potential therapeutic targets for improving HCC therapy. Future investigations are warranted to validate the target genes reported in this study using a larger sample size and more targeted molecular technique.

MicroRNA-34 and gastrointestinal cancers: a player with big functions

It is commonly assumed that gastrointestinal cancer is the most common form of cancer across the globe and is the leading contributor to cancer-related death. The intricate mechanisms underlying the growth of GI cancers have been identified. It is worth mentioning that both non-coding RNAs (ncRNAs) and certain types of RNA, such as circular RNAs (circRNAs), long non-coding RNAs (lncRNAs), and microRNAs (miRNAs), can have considerable impact on the development of gastrointestinal (GI) cancers. As a tumour suppressor, in the group of short non-coding regulatory RNAs is miR-34a. miR-34a silences multiple proto-oncogenes at the post-transcriptional stage by targeting them, which inhibits all physiologically relevant cell proliferation pathways. However, it has been discovered that deregulation of miR-34a plays important roles in the growth of tumors and the development of cancer, including invasion, metastasis, and the tumor-associated epithelial-mesenchymal transition (EMT). Further understanding of miR-34a's molecular pathways in cancer is also necessary for the development of precise diagnoses and effective treatments. We outlined the most recent research on miR-34a functions in GI cancers in this review. Additionally, we emphasize the significance of exosomal miR-34 in gastrointestinal cancers.

Dysregulation of autophagy in gastric carcinoma: Pathways to tumor progression and resistance to therapy

The considerable death rates and lack of symptoms in early stages of gastric cancer (GC) make it a major health problem worldwide. One of the most prominent risk factors is infection with Helicobacter pylori. Many biological processes, including those linked with cell death, are disrupted in GC. The cellular "self-digestion" mechanism necessary for regular balance maintenance, autophagy, is at the center of this disturbance. Misregulation of autophagy, however, plays a role in the development of GC. In this review, we will examine how autophagy interacts with other cell death processes, such as apoptosis and ferroptosis, and how it affects the progression of GC. In addition to wonderful its role in the epithelial-mesenchymal transition, it is engaged in GC metastasis. The role of autophagy in GC in promoting drug resistance stands out. There is growing interest in modulating autophagy for GC treatment, with research focusing on natural compounds, small-molecule inhibitors, and nanoparticles. These approaches could lead to breakthroughs in GC therapy, offering new hope in the fight against this challenging disease.

NAD-Dependent Protein Deacetylase Sirtuin-1 Mediated Mitophagy Regulates Early Brain Injury After Subarachnoid Hemorrhage

Background

This study focuses on the role of SIRT1 in neuroinflammation caused by early brain injury (EBI) after subarachnoid hemorrhage (SAH), and explores its mechanism in mitophagy after SAH.

Methods

C57BL/6J mice and primary microglia SAH in vivo and in vitro models were constructed to explore the expression level of SIRT1 in neuroinflammation after SAH. Subsequently, the brain edema content, blood-brain barrier (BBB) damage and neurological function scores of the mice were observed after using the SIRT1 inhibitor EX-527. q-PCR and Western blot were used to detect relevant genes and proteins, and enzyme-linked immunosorbent assay (ELISA) was used to detect the levels of IL-6, IL-1β, and TNF-α inflammatory factors. Immunofluorescence staining was used to observe the positive level of SIRT1 and the degree of mitochondria-lysosome fusion, and transmission electron microscopy was used to observe mitochondrial damage and autophagosome levels.

Results

In in vivo and in vitro experiments, we found that SIRT1 expression increased after SAH, and neurological deficits, brain edema, and blood-brain barrier damage after SAH were aggravated. Inhibiting SIRT1 further aggravates the aforementioned damage. In addition, EX-527 can also inhibit the level of mitophagy and aggravate neuroinflammation after SAH.

Conclusion

Our results indicated that SIRT1 promotes mitophagy and alleviates neuroinflammation after SAH.

Role of sirtuin 1 (SIRT1) in regulation of autophagy and nuclear factor-kappa Beta (NF-ĸβ) pathways in sorafenib-resistant hepatocellular carcinoma (HCC)

Hepatocellular carcinoma (HCC) remains a major global health problem with high incidence and mortality. Diagnosis of HCC at late stages and tumour heterogeneity in patients with different genetic profiles are known factors that complicate the disease treatment. HCC therapy becomes even more challenging in patients with drug resistance such as resistance to sorafenib, which is a common drug used in HCC patients. Sorafenib resistance can further aggravate HCC by regulating various oncogenic pathways such as autophagy and nuclear factor-kappa Beta (NF-ĸβ) signalling. Sirtuin 1 (SIRT1), is a nicotinamide adenosine dinucleotide (NAD)-dependent histone deacetylases that regulates various metabolic and oncogenic events such as cell survival, apoptosis, autophagy, tumourigenesis, metastasis and drug resistance in various cancers, but its role in HCC, particularly in sorafenib resistance is underexplored. In this study, we generated sorafenib-resistant HepG2 and Huh-7 liver cancer cell models to investigate the role of SIRT1 and its effect on autophagy and nuclear factor-kappa Beta (NF-ĸβ) signalling pathways. Western blot analysis showed increased SIRT1, altered autophagy pathway and activated NF-ĸβ signalling in sorafenib-resistant cells. SIRT1-silenced HCC cells demonstrated down-regulated autophagy in both parental and chemoresistant cells. This may occur through the deacetylation of key autophagy molecules such as FOXO3, beclin 1, ATGs and LC3 by SIRT1, highlighting the role of SIRT1 in autophagy induction. Silencing of SIRT1 also resulted in activated NF-ĸβ signalling. This is because SIRT1 failed to deacetylate p65 subunit of NF-κB, translocate the NF-κB from nucleus to cytoplasm, and suppress NF-κB activity due to the silencing. Hence, the NF-κB transcriptional activity was restored. These findings summarize the role of SIRT1 in autophagy/NF-ĸβ regulatory axis, with a similar trend observed in both parental and sorafenib-resistant cells. The present work promotes a better understanding of the role of SIRT1 in autophagy and NF-ĸβ signalling in HCC and sorafenib-resistant HCC. As some key proteins in these pathways are potential therapeutic targets, a better understanding of SIRT1/autophagy/NF-ĸβ axis could further improve the therapeutic strategies against HCC.

Sirt6-Mediated Cell Death Associated with Sirt1 Suppression in Gastric Cancer

BACKGROUND

Gastric cancer, one of the leading causes of cancer-related death, is strongly associated with H. pylori infection, although other risk factors have been identified. The sirtuin (Sirt) family is involved in the tumorigenesis of gastric cancer, and sirtuins can have pro- or anti-tumorigenic effects.

METHODS

After determining the overall survival rate of gastric cancer patients with or without Sirt6 expression, the effect of Sirt6 upregulation was also tested using a xenograft mouse model. The regulation of Sirt6 and Sirt1, leading to the induction of mouse double minute 2 homolog (MDM2) and reactive oxygen species (ROS), was mainly analyzed using Western blotting and immunofluorescence staining, and gastric cancer cell (SNU-638) death associated with these proteins was measured using flow cytometric analysis.

RESULTS

Sirt6 overexpression led to Sirt1 suppression in gastric cancer cells, resulting in a higher level of gastric cancer cell death in vitro and a reduced tumor volume. ROS and MDM2 expression levels were upregulated by Sirt6 overexpression and/or Sirt1 suppression according to Western blot analysis. The upregulated ROS ultimately led to gastric cancer cell death as determined via Western blot and flow cytometric analysis.

CONCLUSION

We found that the upregulation of Sirt6 suppressed Sirt1, and Sirt6- and Sirt1-induced gastric cancer cell death was mediated by ROS production. These findings highlight the potential of Sirt6 and Sirt1 as therapeutic targets for treating gastric cancer.

Setd2 deficiency promotes gastric tumorigenesis through inhibiting the SIRT1/FOXO pathway

Gastric cancer (GC) is the fifth most common cancer and the second leading cause of cancer death globally. SETD2 is a histone methyltransferase catalyzing tri-methylation of H3K36 (H3K36me3) and has been shown to participate in diverse biological processes and human tumors. However, the mechanism of SETD2 in GC remains unclear. Here, we reported that Setd2 deficiency predicts poor prognosis of gastric cancer. SETD2 loss facilitated H. felis/MNU and c-Myc-induced gastric tumorigenesis, respectively. The mouse model of stomach-specific Setd2 depletion together with c-MYC overexpression (AMS) developed high-grade epithelial defects, intestinal metaplasia and dysplasia at only 10-12 weeks of age. Mechanistically, Setd2 depletion resulted in impaired epigenetic regulation of Sirt1, thus inhibiting the SIRT1/FOXO pathway. Moreover, the agonists of FOXO signaling or overexpression of SIRT1 significantly rescued the enhanced cell proliferation and migration caused by Setd2 deficiency in SGC7901 cells. Together, our findings highlight an epigenetic mechanism by which SETD2 regulates gastric tumorigenesis through SIRT1/FOXO pathway. It may also pave the way for the development of targeted, patient-tailored therapies for GC patients with Setd2 deficiency.

Activation of SIRT1 by hyperbaric oxygenation promotes recovery of motor dysfunction in spinal cord injury rats

BACKGROUND

Hyperbaric oxygenation (HBO) therapy can improve locomotor dysfunction following spinal cord injury (SCI). Emerging evidence has demonstrated that sirtuin1 (SIRT1) exerts protective effects on neurons. However, whether HBO alleviates locomotor dysfunction by regulating SIRT1 is unclear.

METHODS

The traumatic SCI animal model was performed on the adult Sprague-Dawley rats. The Basso, Beattie Bresnahan (BBB) locomotor rating scale was used to evaluate the open-field locomotor function. Western blot, real-time quantitative reverse transcription polymerase chain reaction, SIRT1 activity assay, and enzyme-linked immunosorbent assays were performed to explore the molecular mechanisms.

RESULTS

We found that series HBO therapy significantly improved locomotor dysfunction and ameliorated the decreased mRNA, protein, and activity of spinal cord SIRT1 induced by traumatic SCI injury in rats. In addition, intraperitoneal injection of SIRT1 inhibitor EX-527 abolished the beneficial effects of series HBO treatment on locomotor deficits. Importantly, series HBO treatment following the traumatic SCI injury inhibited the inflammatory cascade and apoptosis-related protein, which was retained by EX-527 and enhanced by SRT1720. Furthermore, EX-527 blocked the enhanced induction of autophagy series with the HBO application.

CONCLUSION

These findings demonstrated a new mechanism for series HBO therapy involving activation of SIRT1 and subsequent modulation of the inflammatory cascade, apoptosis, and autophagy, which contributed to the recovery of motor dysfunction.

ATGL promotes colorectal cancer growth by regulating autophagy process and SIRT1 expression

CRC is a common malignant tumor in the gastrointestinal tract, and its incidence has increased significantly in recent years. Several studies revealed that lipid metabolism reprogramming contributed to tumorigenicity and malignancy by interfering with energy production, membrane formation, and signal transduction in cancers. ATGL is a kind of hydroxy fatty acid ester of fatty acid synthase, and its role in tumor remains controversial. We compared levels of adipose triglyceride lipase (ATGL) in human CRC specimens to adjacent specimens. To validate the effect of ATGL on the proliferation ability of CRC, CCK8 assay and clone formation assay were performed. To evaluate whether autophagy process takes part in the effect of ATGL on CRC proliferation, the value of LC3-II/LC3-I was detected by western blot and we blocked the SIRT1 to detect value of LC3-II/LC3-I and p62 via western blot. In the end, we detected the value of SIRT1 in CRC specimens. We found that ATGL showed high expression in CRC and positively correlated with clinical stage, indicating poor prognosis of CRC. Moreover, ATGL significantly promoted tumor cell proliferation in vitro. Mechanistically, ATGL promoted CRC cells proliferation by blocking mTOR signaling pathway and activating autophagy process. Further, ATGL regulated autophagy process through triggering SIRT1 expression. Our results reveal that ATGL promotes colorectal cancer growth by up regulating autophagy process and SIRT1 expression.

Targeting SIRT1-regulated autophagic cell death as a novel therapeutic avenue for cancer prevention

Cellular localization and deacetylation activity of sirtuin 1 (SIRT1) has a significant role in cancer regulation. The multifactorial role of SIRT1 in autophagy regulates several cancer-associated cellular phenotypes, aiding cellular survival and cell death induction. SIRT1-mediated deacetylation of autophagy-related genes (ATGs) and associated signaling mediators control carcinogenesis. The hyperactivation of bulk autophagy, disrupted lysosomal and mitochondrial biogenesis, and excessive mitophagy are key mechanism for SIRT1-mediated autophagic cell death (ACD). In terms of the SIRT1-ACD nexus, identifying SIRT1-activating small molecules and understanding the possible mechanism triggering ACD could be a potential therapeutic avenue for cancer prevention. In this review, we provide an update on the structural and functional intricacy of SIRT1 and SIRT1-mediated autophagy activation as an alternative cell death modality for cancer prevention.

SIRT1 and SIRT6: The role in aging-related diseases

Aging is characterized by progressive functional deterioration with increased risk of mortality. It is a complex biological process driven by a multitude of intertwined mechanisms such as increased DNA damage, chronic inflammation, and metabolic dysfunction. Sirtuins (SIRTs) are a family of NAD⁺-dependent enzymes that regulate fundamental biological functions from genomic stability and lifespan to energy metabolism and tumorigenesis. Of the seven mammalian SIRT isotypes (SIRT1-7), SIRT1 and SIRT6 are well-recognized for regulating signaling pathways related to aging. Herein, we review the protective role of SIRT1 and SIRT6 in aging-related diseases at molecular, cellular, tissue, and whole-organism levels. We also discuss the therapeutic potential of SIRT1 and SIRT6 modulators in the treatment of these diseases and challenges thereof.

SIRT1/APE1 promotes the viability of gastric cancer cells by inhibiting p53 to suppress ferroptosis

Gastric cancer (GC) is a common cancer worldwide with high mortality. Sirtuin 1 (SIRT1) and apurinic/apyrimidinic endodeoxyribonuclease 1 (APE1) are abnormally expressed in GC cells and related to p53, which is involved in ferroptosis. Thus, we explore the mechanism via which SIRT1, APE1, and p53 impact ferroptosis in GC cells. Specifically, GC cells were transfected with small-interfering RNA for SIRT1 (SiSIRT1) or small-interfering RNA for APE1 (SiAPE1) or with short-hairpin RNA for p53, and the cell viability, Fe²⁺, malondialdehyde (MDA), and glutathione (GSH) contents were detected by cell counting kit-8 assay and enzyme-linked immunosorbent assay. Western blot, immunofluorescence, and quantitative real-time polymerase chain reaction were conducted to quantify SIRT1, APE1, p53, solute carrier family 7 member 11 (SLC7A11), and glutathione peroxidase 4 (GPX4) levels in GC cells. Silencing of SIRT1 decreased viability, GSH content, and expressions of GPX4 and SLC7A11, while increased Fe²⁺, MDA content, and p53 expression in GC cells. Such aforementioned effects were reversed by APE1 overexpression. Also, SiAPE1 generated the same effects as SiSIRT1 on the above aspects, which was offset by p53 silencing. In short, SIRT1/APE1 promotes the growth of GC cells by targeting p53 to inhibit ferroptosis.

Sirtuins (SIRTs) As a Novel Target in Gastric Cancer

Gastric cancer is a major health burden worldwide. Among all neoplasms, gastric cancer is the fifth most common and the third most deadly type of cancer. It is known that sirtuins (SIRTs), are NAD⁺-dependent histone deacetylases regulating important metabolic pathways. High expression of SIRTs in the human body can regulate metabolic processes; they prevent inflammation but also resist cell death and aging processes. The seven members of this family enzymes can also play a fundamental role in process of carcinogenesis by influencing cell viability, apoptosis and metastasis. This review collects and discusses the role of all seven sirtuins (SIRT1-SIRT7) in the pathogenesis of gastric cancer (GC).

Patchouli alcohol ameliorates the learning and memory impairments in an animal model of Alzheimer's disease via modulating SIRT1

BACKGROUND

Alzheimer's disease (AD) is one of the most prevalent neurodegenerative diseases. Patchouli alcohol (PA), a major active ingredient isolated from Pogostemonis Herba, exhibits extensive bioactivity in the central nervous system (CNS) and exerts neuroprotective effects.

PURPOSE

This study aimed to investigate the anti-AD effects of PA in an animal model of AD and to elucidate the underlying molecular mechanisms.

METHODS

The gas chromatography (GC) was used to determine the ability of PA to pass the blood-brain barrier (BBB) in rats after oral administration. The sporadic AD rat model was established by intracerebroventricularly (ICV) injection with streptozotocin (STZ). PA (25 and 50 mg/kg) was given to rat orally once daily for 42 consecutive days. Morris water maze (MWM) test was performed to determine the learning and memory functions of the STZ-induced AD rats. EX527, a silent information regulator 1 (SIRT1) selective inhibitor, was used to investigate the involvement of SIRT1 in the anti-AD effects of PA in rats.

RESULTS

PA could penetrate the BBB. MWM test results showed that PA could significantly ameliorate the learning and memory deficits induced by STZ in rats. Meanwhile, PA enhanced the expression of SIRT1, and markedly alleviated the tau pathology by inhibiting the hyperacetylation (at the site of Lys174) and hyperphosphorylation (at the sites of Thr181, Thr205, Ser396 and Ser404) of tau protein. PA also efficiently suppressed the activation of microglia and astrocytes, and the beta-amyloid (Aβ) expression and the deacetylation of nuclear factor-kappa B (NF-κB) at Lys 310 (K310) in the STZ-treated AD rats. EX527, a SIRT1 selective inhibitor, could partially abolish the cognitive deficits improving effect of PA and inhibit the down-regulation of acetylated tau and acetylated NF-κB p65, suggesting that PA exhibited neuroprotective effects against AD via upregulating SIRT1.

CONCLUSION

This study reported for the first time that PA could penetrate the BBB to exert its protective effects on the brain after a single-dose oral administration. The current experimental findings also amply demonstrated that PA could improve the cognitive and memory impairments in the STZ-induced AD rat model. The underlying mechanisms involve the alleviations of neuroinflammation, tau pathology and Aβ deposition via modulating of SIRT1 and NF-κB pathways. All these findings strongly suggest that PA is a promising naturally occurring compound worthy of further development into an anti-AD pharmaceutical.

Autophagy: A Versatile Player in the Progression of Colorectal Cancer and Drug Resistance

Colorectal cancer (CRC) is among the topmost malignancies for both genders. Despite the high incidence rate and advances in diagnostic tools, treatment in many cases is still ineffective. Most cancerous lesions in CRC begin as benign, followed by the development of invasive forms and metastases. The development of CRC has been linked to defects in autophagy, which plays both a pro-and anti-tumor role and is mainly context-dependent. Autophagy suppression could enhance apoptosis via p53 activation, or autophagy also promotes tumor progression by maintaining tumor growth and increasing resistance to chemotherapy. Autophagy promotes the invasion and metastasis of CRC cells via increased epithelial-mesenchymal transition (EMT). Moreover, dysbiosis of gut microbiota upregulated autophagy and metastasis markers. Autophagy responses may also modulate the tumor microenvironment (TME) via regulating the differentiation process of several innate immune cells. Treatments that promote tumor cell death by stimulating or inhibiting autophagy could be beneficial if used as an adjunct treatment, but the precise role of various autophagy-modulating drugs in CRC patients is needed to be explored. In this article, we present an overview of the autophagy process and its role in the pathogenesis and therapeutic resistance of CRC. Also, we focused on the current understanding of the role of the EMT and TME, including its relation to gut microbiota and immune cells, in autophagic manipulation of CRC. We believe that there is a potential link between autophagy, TME, EMT, and drug resistance, suggesting that further studies are needed to explore this aspect.

Role of olmesartan in ameliorating diabetic nephropathy in rats by targeting the AGE/PKC, TLR4/P38-MAPK and SIRT-1 autophagic signaling pathways

Diabetic nephropathy (DN) is one of the most serious consequences of diabetes and the most common reason for end-stage renal disease. The current study was set out to investigate the ability of olmesartan medoxomil (OM) to treat DN by evaluating the reno-protective effects of this drug on fat/fructose/streptozotocin (F/Fr/STZ)-induced diabetic rat model. This model was induced by feeding rats high F/Fr diet for 7 weeks followed by injection of a single sub-diabetogenic dose of STZ (35mg/kg; i.p). The F/Fr/STZ-induced diabetic rats were orally treated with either OM (10 mg/kg) or pioglitazone (10 mg/kg); as a standard drug daily for four consecutive weeks. F/Fr/STZ-induced diabetic rats propagated inflammatory, oxidative, and fibrotic events. OM was able to oppose the injurious effects of diabetes; it significantly reduced the elevated levels of advanced glycated end products (AGEs) and downregulated PKC gene expression, therefore, indicating its antioxidant capacity evidenced by mitigation in GSH, MDA renal content. Moreover, OM impaired the inflammatory cascade by suppressing the elevated level of renal TLR4 as well as diminished the inflammatory profibrotic cytokine TGF-β1. Additionally, OM was able to turn off the MAPK cascade mediated by an upsurge in renal angiotensin 1-7 content and decrease the level of renal tubular injury marker, KIM-1. Furthermore, OM enhanced the autophagic activity pathway by upregulating of gene expression of SIRT-1. The histopathological examination confirmed these results. Finally, OM protected against type 2 diabetes-related nephropathy complications by altering inflammatory pathways, oxidative, fibrotic, and autophagic processes triggered by renal glucose overload. This study shows that OM has a reno-protective effect against DN in rats by inhibiting the AGE/PKC, TLR4/P38-MAPK, and SIRT-1 autophagic signaling pathways.

Upregulation of SIRT1 Contributes to dmPGE2-dependent Radioprotection of Hematopoietic Stem Cells

Exposure to potentially lethal high-dose ionizing radiation results in bone marrow suppression, known as the hematopoietic acute radiation syndrome (H-ARS), which can lead to pancytopenia and possible death from hemorrhage or infection. Medical countermeasures to protect from or mitigate the effects of radiation exposure are an ongoing medical need. We recently reported that 16,16 dimethyl prostaglandin E₂ (dmPGE₂) given prior to lethal irradiation protects hematopoietic stem (HSCs) and progenitor (HPCs) cells and accelerates hematopoietic recovery by attenuating mitochondrial compromise, DNA damage, apoptosis, and senescence. However, molecular mechanisms responsible for the radioprotective effects of dmPGE₂ on HSCs are not well understood. In this report, we identify a crucial role for the NAD⁺-dependent histone deacetylase Sirtuin 1 (Sirt1) downstream of PKA and CREB in dmPGE₂-dependent radioprotection of hematopoietic cells. We found that dmPGE₂ increases Sirt1 expression and activity in hematopoietic cells including HSCs and pharmacologic and genetic suppression of Sirt1 attenuates the radioprotective effects of dmPGE₂ on HSC and HPC function and its ability to reduce DNA damage, apoptosis, and senescence and stimulate autophagy in HSCs. DmPGE₂-mediated enhancement of Sirt1 activity in irradiated mice is accompanied by epigenetic downregulation of p53 activation and inhibition of H3K9 and H4K16 acetylation at the promoters of the genes involved in DNA repair, apoptosis, and autophagy, including p53, Ku70, Ku80, LC3b, ATG7, and NF-κB. These studies expand our understanding of intracellular events that are induced by IR but prevented/attenuated by dmPGE₂ and suggest that modulation of Sirt1 activity may facilitate hematopoietic recovery following hematopoietic stress. Graphical Abstract.

Non-coding RNAs and glioblastoma: Insight into their roles in metastasis

Glioma, also known as glioblastoma multiforme (GBM), is the most prevalent and most lethal primary brain tumor in adults. Gliomas are highly invasive tumors with the highest death rate among all primary brain malignancies. Metastasis occurs as the tumor cells spread from the site of origin to another site in the brain. Metastasis is a multifactorial process, which depends on alterations in metabolism, genetic mutations, and the cancer microenvironment. During recent years, the scientific study of non-coding RNAs (ncRNAs) has led to new insight into the molecular mechanisms involved in glioma. Many studies have reported that ncRNAs play major roles in many biological procedures connected with the development and progression of glioma. Long ncRNAs (lncRNAs), microRNAs (miRNAs), and circular RNAs (circRNAs) are all types of ncRNAs, which are commonly dysregulated in GBM. Dysregulation of ncRNAs can facilitate the invasion and metastasis of glioma. The present review highlights some ncRNAs that have been associated with metastasis in GBM. miRNAs, circRNAs, and lncRNAs are discussed in detail with respect to their relevant signaling pathways involved in metastasis.

Clinical value of SIRT1 as a prognostic biomarker in esophageal squamous cell carcinoma, a systematic meta-analysis

Several studies reported that the expression of SIRT1 was associated with the clinical features of patients with esophageal squamous cell carcinoma (ESCC), but the function remains inconsistent. We conducted this study to illustrate the clinical value of SIRT1 expression in the early diagnosis and prediction of prognosis of ESCC. In this study, PubMed, Embase, and Web of Science were searched by two independent researchers and STATA14.0 software was used to conduct meta-analysis. The odds ratio with 95% confidence interval was used to estimate the pooled effect. Egger’s test and Begg’s funnel were used to assess publication bias. Sensitivity analysis was used to evaluate the reliability and stability of meta-analysis results. According to the inclusion and exclusion criteria, six studies were enrolled, including 811 cases of ESCC. Results of the meta-analysis indicated that SIRT1 was overexpressed in ESCC and the SIRT1 expression was closely related to the clinicopathological features of ESCC, such as tumor infiltration, tumor node metastasis (TNM) stage, and lymph node metastasis. In the survival analysis, high expression of SIRT1 represented a poor prognosis in ESCC patients. Our study demonstrated that SIRT1 was overexpressed in ESCC, and it might be a potential biomarker for progress of ESCC.

Autophagy Regulation by Crosstalk between miRNAs and Ubiquitination System

MicroRNAs (miRNAs) are non-coding single-stranded RNA molecules encoded by endogenous genes with ~22 nucleotides which are involved in the regulation of post-transcriptional gene expression. Ubiquitination and deubiquitination are common post-translational modifications in eukaryotic cells and important pathways in regulating protein degradation and signal transduction, in which E3 ubiquitin ligases and deubiquitinases (DUBs) play a decisive role. MiRNA and ubiquitination are involved in the regulation of most biological processes, including autophagy. Furthermore, in recent years, the direct interaction between miRNA and E3 ubiquitin ligases or deubiquitinases has attracted much attention, and the cross-talk between miRNA and ubiquitination system has been proved to play key regulatory roles in a variety of diseases. In this review, we summarized the advances in autophagy regulation by crosstalk between miRNA and E3 ubiquitin ligases or deubiquitinases.

TFEB, SIRT1, CARM1, Beclin-1 expression and PITX2 methylation in breast cancer chemoresistance: a retrospective study

BACKGROUND

Breast cancer chemoresistance is attributed to a wide variety of mechanisms, including autophagy. Transcription factor EB (TFEB) has been recently identified and characterized as one major regulator of autophagy and lysosomal genesis.

OBJECTIVE

This study aims to evaluate the prognostic impact of TFEB and its pathway in breast cancer chemoresistance.

METHODS

This retrospective study analyzes the expression of TFEB, CARM1, SIRT1, and Beclin-1 and the methylation of PITX2 in breast carcinoma. A group of breast cancer patients treated with chemotherapy, who relapsed within 12 months from treatment initiation, were compared to a sub-cohort of chemo-treated patients who did not recur within 12 months of follow-up. The expression of TFEB, CARM1, SIRT1, and Belcin-1 was analyzed using immunohistochemistry or RT-PCR on formalin-fixed paraffin-embedded samples. PITX2 methylation was tested with the diagnostic CE-marked kit Therascreen PITX2 RGQ PCR. In the final model, 136 cases of chemo-treated breast cancer were included.

RESULTS

A higher TFEB and Beclin-1 expression correlate with shorter survival in patients with chemo-treated invasive breast cancer (respectively HR 3.46, CI.95 1.27-9.47, p < 0.05 and 7.11, CI.95 2.54-19.9). TFEB, CARM1, and SIRT1 are positively correlated with Beclin-1. The protein expression of SIRT1 is significantly associated with TFEB and CARM1 so that a very low SIRT1 expression (lower than the first quartile of the H-score distribution) correlates with a low expression of TFEB and CARM1 and with longer survival. SIRT1 seems to have a lower H-score in the basal-like and HER2-enriched tumors than the luminal subtypes. Beclin-1 and TFEB seem to have a higher H-score in the basal-like and HER2-enriched tumors than the luminal subtypes. PITX2 methylation analysis was feasible only in 65% of the selected samples, but no significant differences between cases and controls were found, and there was also no correlation with the expression of the TFEB pathway.

CONCLUSIONS

TFEB, SIRT1, and Beclin-1 seem to have a potential prognostic significance in patients with chemo-treated breast cancer, likely because of their role in the regulation of autophagy. In addition, no correlation between TFEB and PITX2 methylation was found, likely because they perform two different roles within the autophagy process.

Characterization of Histone Deacetylase Mechanisms in Cancer Development

Over decades of studies, accumulating evidence has suggested that epigenetic dysregulation is a hallmark of tumours. Post-translational modifications of histones are involved in tumour pathogenesis and development mainly by influencing a broad range of physiological processes. Histone deacetylases (HDACs) and histone acetyltransferases (HATs) are pivotal epigenetic modulators that regulate dynamic processes in the acetylation of histones at lysine residues, thereby influencing transcription of oncogenes and tumour suppressor genes. Moreover, HDACs mediate the deacetylation process of many nonhistone proteins and thus orchestrate a host of pathological processes, such as tumour pathogenesis. In this review, we elucidate the functions of HDACs in cancer.

Hsa-miR-34a-5p reverses multidrug resistance in gastric cancer cells by targeting the 3'-UTR of SIRT1 and inhibiting its expression

Multidrug resistance (MDR) is a major obstacle to chemotherapy, which leads to ineffective chemotherapy, an important treatment strategy for gastric cancer (GC). The abnormality of microRNAs (miRNAs) is critical to the occurrence and progression of MDR in various tumors. In this study, hsa-miR-34a-5p was found to be decreased in multidrug resistant GC cells SGC-7901/5-Fluorouracil (SGC-7901/5-Fu) compared to the parental SGC-7901 cells. Overexpression of hsa-miR-34a-5p in SGC-7901/5-Fu cells promoted apoptosis and decreased migration and invasiveness after chemotherapy. In addition, overexpression of hsa-miR-34a-5p suppressed the growth of drug-resistant tumor in vivo. The mechanism of the effects of hsa-miR-34a-5p could include the regulation of the expression of Sirtuin 1 (SIRT1), P-glycoprotein (P-gp) or Multidrug resistance-related protein 1 (MRP1) through direct binding to the 3'-untranslated region (UTR) of SIRT1. Functional gain-and-loss experiments indicated that hsa-miR-34a-5p enhances the chemotherapy sensitivity of MDR GC cells by inhibiting SIRT1, P-gp and MRP1. In conclusion, hsa-miR-34a-5p can reverse the MDR of GC cells by inhibiting the expression of SIRT1, P-gp or MRP1.

Sirtuin 1 promotes autophagy and proliferation of endometrial cancer cells by reducing acetylation level of LC3

Endometrial cancer (EC) constitutes a common female genital tract tumor with a rising incidence rate. Sirtuin 1 (SIRT1) is a member of histone deacetylase, which extensively participates in the progression of aging, cell death, and tumorigenesis. This study explored the effect of SIRT1-mediated LC3 acetylation on autophagy and proliferation of EC cells. SIRT1 expression in EC tissues and adjacent tissues, EC cell lines and normal human epithelial cells was detected. SIRT1 expression was elevated in EC cell lines and tissues. Knockdown of SIRT1 inhibited proliferation, migration, and invasion of EC cells. Then, EC cells were starved in serum-free medium, and levels of autophagy-related proteins were detected. Starvation induced autophagy of EC cells. The starvation-treated EC cells showed an increased SIRT1 expression, a decreased LC3 acetylation level and an increased autophagy level. The proliferation and autophagy of EC cells under different treatments were evaluated. In EC cells transfected with overexpressing SIRT1, LC3 acetylation was inhibited and cell proliferation was promoted. Moreover, overexpressing SIRT1 facilitated growth and autophagy of transplanted tumors in nude mice. In conclusion, SIRT1 promoted autophagy and proliferation of EC cells by reducing acetylation level of LC3.

Sirtuins' control of autophagy and mitophagy in cancer

Mammalian cells use a specialized and complex machinery for the removal of altered proteins or dysfunctional organelles. Such machinery is part of a mechanism called autophagy. Moreover, when autophagy is specifically employed for the removal of dysfunctional mitochondria, it is called mitophagy. Autophagy and mitophagy have important physiological implications and roles associated with cellular differentiation, resistance to stresses such as starvation, metabolic control and adaptation to the changing microenvironment. Unfortunately, transformed cancer cells often exploit autophagy and mitophagy for sustaining their metabolic reprogramming and growth to a point that autophagy and mitophagy are recognized as promising targets for ongoing and future antitumoral therapies. Sirtuins are NAD+ dependent deacylases with a fundamental role in sensing and modulating cellular response to external stresses such as nutrients availability and therefore involved in aging, oxidative stress control, inflammation, differentiation and cancer. It is clear, therefore, that autophagy, mitophagy and sirtuins share many common aspects to a point that, recently, sirtuins have been linked to the control of autophagy and mitophagy. In the context of cancer, such a control is obtained by modulating transcription of autophagy and mitophagy genes, by post translational modification of proteins belonging to the autophagy and mitophagy machinery, by controlling ROS production or major metabolic pathways such as Krebs cycle or glutamine metabolism. The present review details current knowledge on the role of sirtuins, autophagy and mitophagy in cancer to then proceed to discuss how sirtuins can control autophagy and mitophagy in cancer cells. Finally, we discuss sirtuins role in the context of tumor progression and metastasis indicating glutamine metabolism as an example of how a concerted activation and/or inhibition of sirtuins in cancer cells can control autophagy and mitophagy by impinging on the metabolism of this fundamental amino acid.

Combined effects on leukemia cell growth by targeting sphingosine kinase 1 and sirtuin 1 signaling

Targeting multiple signaling pathways is a potential novel therapeutic strategy for the treatment of leukemias. Leukemia cells express high levels of sphingosine kinase 1 (Sphk1) and sirtuin 1 (SIRT1). However, to the best of our knowledge, their interaction and potential synergistic inhibitory effects on the growth and survival of leukemia cells have not been investigated. The present study revealed the role of the Sphk1/S1P/SIRT1 axis in K562, KCL22 and TF1 cells and hypothesized that the inhibition of Sphk1 and SIRT1 had synergistic effects on the growth and survival of leukemia cells. Cell viability was tested using a Cell Counting Kit-8 assay and cell colony forming assay. Cell apoptosis was detected using Annexin V-APC/PI staining. The stages of the cell cycle were measured using PI staining. Protein levels were measured by western blotting. Treatment of leukemia cells with S1P resulted in the upregulation of SIRT1 expression, whereas inhibition of Sphk1 induced SIRT1 downregulation in leukemia cells. Both SKI-II and EX527 actively suppressed growth, blocked cell cycle progression and induced apoptosis of leukemia cells. Furthermore, inhibition of Sphk1 and SIRT1 exhibited suppressive effects on the growth and survival of leukemia cells. Notably, the inhibition of Sphk1 and SIRT1 suppressed cell growth and induced apoptosis of T-315I mutation-harboring cells. Additionally, treatment with SKI-II and EX527 suppressed the ERK and STAT5 pathways in leukemia cells. These data indicated that targeting the Sphk1/S1P/SIRT1 axis may be a novel therapeutic strategy for the treatment of leukemia.

NUCKS promotes cell proliferation and suppresses autophagy through the mTOR-Beclin1 pathway in gastric cancer

Background

Nuclear casein kinase and cyclin-dependent kinase substrate (NUCKS), a novel gene first reported in 2001, is a member of the high mobility group (HMG) family. Although very little is known regarding the biological roles of NUCKS, emerging clinical evidence suggests that the NUCKS protein can be used as a biomarker and therapeutic target in various human ailments, including several types of cancer.

Methods

We first assessed the potential correlation between NUCKS expression and gastric cancer prognosis. Then functional experiments were conducted to evaluate the effects of NUCKS in cell proliferation, cell cycle, apoptosis and autophagy. Finally, the roles of NUCKS on gastric cancer were examined in vivo.

Results

We found that NUCKS was overexpressed in gastric cancer patients with poor prognosis. Through manipulating NUCKS expression, it was observed to be positively associated with cell proliferation in vitro and in vivo. NUCKS knockdown could induce cell cycle arrest and apoptosis. Then further investigation indicated that NUCKS knockdown could also significantly induce a marked increase in autophagy though the mTOR-Beclin1 pathway, which could be was rescued by NUCKS restoration. Moreover, silencing Beclin1 in NUCKS knockdown cells or adding rapamycin in NUCKS-overexpressed cells also confirmed these results.

Conclusions

Our findings revealed that NUCKS functions as an oncogene and an inhibitor of autophagy in gastric cancer. Thus, the downregulation or inhibition of NUCKS may be a potential therapeutic strategy for gastric cancer.

CD38 Causes Autophagic Flux Inhibition and Cardiac Dysfunction Through a Transcriptional Inhibition Pathway Under Hypoxia/Ischemia Conditions

Induced autophagy is protective against myocardial hypoxia/ischemia (H/I) injury, but evidence regarding the extent of autophagic clearance under H/I and the molecular mechanisms that influence autophagic flux has scarcely been presented. Here, we report that CD38 knockout improved cardiac function and autophagic flux in CD38^–/– mice and CD38^–/– neonatal cardiomyocytes (CMs) under H/I conditions. Mechanistic studies demonstrated that overexpression of CD38 specifically downregulated the expression of Rab7 and its adaptor protein pleckstrin homology domain-containing protein family member 1 (PLEKHM1) through nicotinamide adenine dinucleotide (NAD)-dependent and non-NAD-dependent pathways, respectively. Loss of Rab7/PLEKHM1 impaired the fusion of autophagosomes and lysosomes, resulting in autophagosome accumulation in the myocardium and consequent cardiac dysfunction under H/I conditions. Thus, CD38 mediated autophagic flux blockade and cardiac dysfunction in a Rab7/PLEKHM1-dependent manner. These findings suggest a potential therapeutic strategy involving targeted suppression of CD38 expression.

Oncogenic USP22 supports gastric cancer growth and metastasis by activating c-Myc/NAMPT/SIRT1-dependent FOXO1 and YAP signaling

In this study, we investigated the role of ubiquitin-specific protease 22 (USP22) in the growth and progression of gastric cancer (GC). USP22 mRNA and protein levels were significantly higher in GC tissue samples and GC cell lines than in adjacent noncancerous tissue samples and a normal gastric mucosal epithelial cell line (GES1), respectively. USP22 knockdown significantly decreased in vitro survival, proliferation, migration, and invasiveness of GC cells compared with the controls. Western blot analysis of control and USP22-silenced GC cells showed that USP22 modulates the c-Myc/NAMPT/SIRT1-dependent FOXO1 and YAP signaling pathways. Subcutanenous injection of USP22-silenced GC cells into SCID mice generated significantly smaller xenograft tumors than did control cells. Moreover, USP22-silenced GC cells showed less lung metastasis than the controls following tail vein injection in SCID mice. In addition, high USP22 expression correlated positively with tumor size, advanced stage and metastasis, and correlated negatively with tumor differentiation and prognosis in GC patients. These results show that USP22 regulates growth and progression of GC via the c-Myc/NAMPT/SIRT1-dependent FOXO1 and YAP signaling pathways.

Mechanisms and disease implications of sirtuin-mediated autophagic regulation

Accumulating evidence has indicated that sirtuins are key components of diverse physiological processes, including metabolism and aging. Sirtuins confer protection from a wide array of metabolic and age-related diseases, such as cancer, cardiovascular and neurodegenerative diseases. Recent studies have also suggested that sirtuins regulate autophagy, a protective cellular process for homeostatic maintenance in response to environmental stresses. Here, we describe various biological and pathophysiological processes regulated by sirtuin-mediated autophagy, focusing on cancer, heart, and liver diseases, as well as stem cell biology. This review also emphasizes key molecular mechanisms by which sirtuins regulate autophagy. Finally, we discuss novel insights into how new therapeutics targeting sirtuin and autophagy may potentially lead to effective strategies to combat aging and aging-related diseases.

Harnessing the protective powers of a family of proteins could help tackle age-related diseases. In a review of recent research, In Hye Lee at Ewha Womans University in Seoul, South Korea, explores links between the sirtuin protein family and autophagy, a natural process involving the degradation and recycling of cellular components. In mammals, the sirtuin family comprises seven proteins that are found in specific locations across the body, and play key roles in many biological processes from metabolism to the regulation of autophagy. As we age, autophagic balance becomes disrupted, leaving us vulnerable to diseases such as cancer and neurodegenerative disorders. Indeed, cancerous tumors can exploit autophagic processes for their own benefit. Lee’s review suggests that therapies targeting sirtuins could restore and maintain autophagic balance, potentially helping to control aging and age-related disorders.

Combination Therapy of Chloroquine and C₂-Ceramide Enhances Cytotoxicity in Lung Cancer H460 and H1299 Cells

Non-small cell lung cancer (NSCLC) is a type of malignant cancer, and 85% of metastatic NSCLC patients have a poor prognosis. C₂-ceramide induces G2/M phase arrest and cytotoxicity in NSCLC cells. In this study, the autophagy-inducing effect of C₂-ceramide was demonstrated, and cotreatment with the autophagy inhibitor chloroquine (CQ) was investigated in NSCLC H460 and H1299 cells. The results suggested that C₂-ceramide exhibited dose-dependent anticancer effects in H460 and H1299 cells and autophagy induction. Zebrafish-based acridine orange staining confirmed the combined effects in vivo. Importantly, the combination of a sublethal dose of C₂-ceramide and CQ resulted in additive cytotoxicity and autophagy in both cell lines. Alterations of related signaling factors, including Src and SIRT1 inhibition and activation of the autophagic regulators LAMP2 and LC3-I/II, contributed to the autophagy-dependent apoptosis. We found that C₂-ceramide continuously initiated autophagy; however, CQ inhibited autophagosome maturation and degradation during autophagy progression. Accumulated and non-degraded autophagosomes increased NSCLC cell stress, eventually leading to cell death. This study sheds light on improvements to NSCLC chemotherapy to reduce the chemotherapy dose and NSCLC patient burden.

Role of histone acetylation in gastric cancer: implications of dietetic compounds and clinical perspectives

Histone modifications regulate the structural status of chromatin and thereby influence the transcriptional status of genes. These processes are controlled by the recruitment of different enzymes to a specific genomic site. Furthermore, obtaining an understanding of these mechanisms could help delineate alternative treatment and preventive strategies for cancer. For example, in gastric cancer, cholecalciferol, curcumin, resveratrol, quercetin, garcinol and sodium butyrate are natural regulators of acetylation and deacetylation enzyme activity that exert chemopreventive and anticancer effects. Here, we review the recent findings on histone acetylation in gastric cancer and discuss the effects of nutrients and bioactive compounds on histone acetylation and their potential role in the prevention and treatment of this type of cancer.

Modulating Effect of Diet on Alzheimer's Disease

As life expectancy is growing, neurodegenerative disorders, such as Alzheimer's disease, are increasing. This disease is characterised by the accumulation of intracellular neurofibrillary tangles formed by hyperphosphorylated tau protein, senile plaques composed of an extracellular deposit of β-amyloid peptide (Aβ), and neuronal loss. This is accompanied by deficient mitochondrial function, increased oxidative stress, altered inflammatory response, and autophagy process impairment. The present study gathers scientific evidence that demonstrates that specific nutrients exert a direct effect on both Aβ production and Tau processing and their elimination by autophagy activation. Likewise, certain nutrients can modulate the inflammatory response and the oxidative stress related to the disease. However, the extent to which these effects come with beneficial clinical outcomes remains unclear. Even so, several studies have shown the benefits of the Mediterranean diet on Alzheimer's disease, due to its richness in many of these compounds, to which can be attributed their neuroprotective properties due to the pleiotropic effect they show on the aforementioned processes. These indications highlight the potential role of adequate dietary recommendations for clinical management of both Alzheimer's diagnosed patients and those in risk of developing it, emphasising once again the importance of diet on health.

Is co-expression of USP22 and HSP90 more effective in predicting prognosis of gastric cancer?

The ubiquitin-specific peptidase 22 (USP22) belongs to the largest subfamily of deubiquitylases and recent studies indicate that overexpression of USP22 may promote gastric cancer progression and predict prognosis. But little is known about the interaction network of USP22 in gastric cancer. In this study, we applied bioinformatics methods and found that USP22 was correlated with the heat shock protein 90 (HSP90) which is now considered to be a biomarker to predict the prognosis of gastric cancer. Then the siRNA transfection and western blotting were used to testify the correlation of USP22 and HSP90 in gastric cancer cells. The immunohistochemistry staining of the microarrays was applied to confirm the correlation of USP22 and HSP90 expression in gastric cancer tissue and further analysis showed that co-expression of USP22 and HSP90 was related to lymph node metastasis and more effective in predicting the prognosis of gastric cancer. In summary, our data demonstrate that correlation exists between USP22 and HSP90 expressions in gastric cancer and co-expression of USP22 and HSP90 may be more effective in predicting prognosis of gastric cancer.

Altered Processing of β-Amyloid in SH-SY5Y Cells Induced by Model Senescent Microglia

The single greatest risk factor for neurodegenerative diseases is aging. Aging of cells such as microglia in the nervous system has an impact not only on the ability of those cells to function but also on cells they interact with. We have developed a model microglia system that recapitulates the dystrophic/senescent phenotype, and we have combined this with the study of β-amyloid processing. The model is based on the observation that aged microglia have increased iron content. By overloading a human microglial cell line with iron, we were able to change the secretory profile of the microglia. When combining these senescent microglia with SH-SY5Y cells, we noted an increase in extracellular β-amyloid. The increased levels of β-amyloid were due to a decrease in the release of insulin-degrading enzyme by the model senescent microglia. Further analysis revealed that the senescent microglia showed both decreased autophagy and increased ER stress. These studies demonstrate the potential impact of an aging microglial population in terms of β-amyloid produced by neurons, which could play a causal role in diseases like Alzheimer's disease. Our results also further develop the potential utility of an in vitro model of senescent microglia for the study of brain aging and neurodegenerative disease.

Effects of hindlimb suspension and reloading on gastrocnemius and soleus muscle mass and function in geriatric mice

Reloading of atrophied muscles after hindlimb suspension (HLS) can induce muscle injury and prolong recovery after disuse in old rats, especially in fast contracting muscles. Less is known about the responses in mice and whether fast and slow muscles from geriatric mice will respond in a similar fashion to HLS unloading and recovery (HLS + R). Furthermore, while slow muscles undergo atrophy with disuse, they typically are more resistant to sarcopenia than fast contracting muscles. Geriatric (28 mo. of age) male C57BL/6 mice were randomly placed into 3 groups. These included HLS for 14 days n = 9, and HLS followed by 14 days of reloading recovery (HLS + R; n = 9), or normal ambulatory cage controls (n = 9). Control mice were not exposed to unloading. Electrically evoked maximal muscle function was assessed in vivo in anesthetized mice at baseline, after 14 days of HLS or HLS + R. As expected, HLS significantly reduced body weight, wet weight of gastrocnemius and soleus muscles and in vivo maximal force. There were no differences in vivo fatigability of the plantar flexor muscles and overall fiber size. There were only minor fiber type distribution and frequency distribution of fiber sizes that differ between HLS + R and control gastrocnemius and soleus muscles. Soleus muscle wet weight had recovered to control levels after reloading, but type I/IIA fibers in the soleus muscles were significantly smaller after HLS + R than control muscles. In contrast, gastrocnemius muscle wet weight did not recover to control levels after reloading. Plantar flexion muscle force (primarily influenced by the gastrocnemius muscles) did not recover in HLS + R conditions as compared to HLS conditions and both were lower than control force production signaling for apoptosis, autophagy and anabolic markers were not different between control and HLS + R gastrocnemius and soleus muscles in geriatric mice. These results suggest that molecular signaling does not explain attenuated ability to regain muscle wet weight, fiber size or muscle force production after HLS in geriatric mice. It is possible that fluid shifts, reduced blood flow, or shortened muscle fibers which failed to regain control lengths contributed to the attenuation of muscle wet weight after HLS and reloading and this affected force production. Further work is needed to determine if altered/loss of neural activity contributed to the inability of geriatric mice to regain gastrocnemius muscle weight and function after HLS and reloading.

Anticancer effect of pan-PI3K inhibitor on multiple myeloma cells: Shedding new light on the mechanisms involved in BKM120 resistance

The correlation between the Phosphoinositide 3-kinase (PI3K) axis and crucial mechanisms involved in the maintenance of the neoplastic nature of multiple myeloma (MM) has recently evolved a general agreement that PI3K inhibition-based therapies could construct an exciting perspective for the future treatment strategies. Our results outlined that abrogation of PI3K using pan-PI3K inhibitor BKM120 decreased survival of MM cells through induction of a caspase-3-dependent apoptosis coupled with SIRT1-mediated G2/M arrest in both KMM-1 and RPMI 8226 cell lines; however, the cell responses to the inhibitor was quite different, introducing wild-type PTEN-expressing RPMI 8226 as less sensitive cells. By investigating the sensitivity extent of a panel of hematological cell lines to BKM120, we found no significant association with respect to PTEN status. As far as we are aware, the results of the present study propose for the first time that the inhibitory effect of BKM120 was overshadowed, at least partially, through over-expression of either c-Myc or nuclear factor (NF)-κB in less sensitive MM cells. While there was no significant effect of the inhibitor on the expression of c-Myc in RPMI 8226, we found an enhanced cytotoxic effect when BKM120 was used in combination with a small molecule inhibitor of c-Myc. Noteworthy, the results of the synergistic experiments also revealed that BKM120 could produce a synergistic anti-cancer effect with carfilzomib (CFZ) and provided an enhanced therapeutic efficacy in MM cells, highlighting that PI3K inhibition might be a befitting approach in MM both in mono and combined therapy.

Hydrogen attenuated oxidized low-density lipoprotein-induced inflammation through the stimulation of autophagy via sirtuin 1

Chronic inflammation is a central pathogenic mechanism underlying the induction and progression of atherosclerosis (AS). Hydrogen has been demonstrated to serve a protective role in diverse models of disease. However, the potential effects and mechanism of hydrogen with respect to ox-LDL-induced inflammation have not yet been completely elucidated. In the present study, various concentrations (0, 50 and 100 mg/l) of oxidized low-density lipoprotein (ox-LDL) were used to treat RAW264.7 cells. A Cell Counting kit-8 assay was used to determine cell viability and western blot analysis was performed to determine the expression of proteins that are involved in autophagy. The expression of inflammatory cytokines in ox-LDL-treated macrophages was detected using ELISA. Small interfering (si)RNA against sirtuin 1 (SIRT1) was employed to investigate the mechanism underlying hydrogen-activated autophagy. The results indicated that ox-LDL stimulation promoted inflammatory cytokine expression and impaired autophagic flux in RAW264.7 cells. Furthermore, hydrogen inhibited ox-LDL-induced inflammatory cytokine expression by upregulating autophagic flux. SIRT1 mediated the upregulation of autophagic flux via hydrogen in ox-LDL-treated macrophages. To conclude, the present study provided novel insights into the role of defective autophagy in the pathogenesis of AS and identified autophagy to be a promising therapeutic target for the treatment of AS. Notably, hydrogen may represent a potential agent for the treatment of AS.

SIRT1 expression regulates the transformation of resistant esophageal cancer cells via the epithelial-mesenchymal transition

Sirtuin1 (SIRT1) belongs to the mammalian sirtuin family and plays an important role in deacetylating histones and non-histones. SIRT1 is associated with tumor metastasis in several tumors. However, the effect of SIRT1 on the mechanism of metastasis in resistant esophageal cancer remains unclear. In this study, we demonstrated that increased migration and invasion in drug-resistant esophageal cancer cells (EC109/PTX, TE-1/PTX). Our experiments revealed that the selective SIRT1 inhibitor (EX527) significantly suppressed cells migrate and inhibited the occurrence of the epithelial-mesenchymal transition (EMT), thereby altering the invasiveness and metastatic potential of the esophageal cancer cell lines. In addition, we observed that the inhibition of SIRT1 could alter the expression of snail. In conclusion, these results indicate that SIRT1 may promote the transformation of tumor cells by inducing the EMT and may serve as a potential molecular target for the treatment of resistant esophageal cancer.

An Interplay between Senescence, Apoptosis and Autophagy in Glioblastoma Multiforme-Role in Pathogenesis and Therapeutic Perspective

Autophagy, cellular senescence, programmed cell death and necrosis are key responses of a cell facing a stress. These effects are partly interconnected, but regulation of their mutual interactions is not completely clear. That regulation seems to be especially important in cancer cells, which have their own program of development and demand more nutrition and energy than normal cells. Glioblastoma multiforme (GBM) belongs to the most aggressive and most difficult to cure cancers, so studies on its pathogenesis and new therapeutic strategies are justified. Using an animal model, it was shown that autophagy is required for GBM development. Temozolomide (TMZ) is the key drug in GBM chemotherapy and it was reported to induce senescence, autophagy and apoptosis in GBM. In some GBM cells, TMZ induces small toxicity despite its significant concentration and GBM cells can be intrinsically resistant to apoptosis. Resveratrol, a natural compound, was shown to potentiate anticancer effect of TMZ in GBM cells through the abrogation G2-arrest and mitotic catastrophe resulting in senescence of GBM cells. Autophagy is the key player in TMZ resistance in GBM. TMZ can induce apoptosis due to selective inhibition of autophagy, in which autophagic vehicles accumulate as their fusion with lysosomes is blocked. Modulation of autophagic action of TMZ with autophagy inhibitors can result in opposite outcomes, depending on the step targeted in autophagic flux. Studies on relationships between senescence, autophagy and apoptosis can open new therapeutic perspectives in GBM.

Autophagy inhibition enhanced 5‑FU‑induced cell death in human gastric carcinoma BGC‑823 cells

The exact molecular mechanism of 5-fluorouracil (5-FU) in human gastric cancer cells remains to be elucidated. Cultured BGC‑823 human gastric carcinoma and AGS cell lines were treated with 5‑FU. Autophagosome formation was investigated through multiple approaches, including the quantification of green fluorescent protein‑microtubule‑associated protein 1A/1B‑light chain 3 (LC3) puncta, LC3 conversion and electron microscopy observations. Additionally, autophagy was inhibited using 3‑methyladenine (3‑MA) and beclin‑1 ablation, to determine its role in 5‑FU‑mediated cell death. In addition, the present study assessed alterations in sirtuin expression following 5‑FU treatment with reverse transcription‑quantitative polymerase chain reaction. 5‑FU treatment induced apoptosis and inhibited proliferation in BGC‑823 and AGS gastric cancer cells. It is of note that the 5‑FU treatment only promoted autophagy in BGC‑823 cells. Additionally, inhibition of autophagy by either 3‑MA or beclin‑1 ablation increased 5‑FU‑induced cell death in BGC‑823 cells. The present study quantified changes in sirtuin (SIRT1, SIRT3, SIRT5, and SIRT6) expression following 5‑FU treatment and using a specific inhibitor, sirtinol, the present study investigated their involvement in 5‑FU‑mediated autophagy. Autophagy inhibition through manipulation of sirtuin proteins may increase the therapeutic efficacy of the 5‑FU chemotherapeutic drug against gastric carcinoma.

Cross-validation of survival associated biomarkers in gastric cancer using transcriptomic data of 1,065 patients

Introduction

Multiple gene expression based prognostic biomarkers have been repeatedly identified in gastric carcinoma. However, without confirmation in an independent validation study, their clinical utility is limited. Our goal was to establish a robust database enabling the swift validation of previous and future gastric cancer survival biomarker candidates.

Results

The entire database incorporates 1,065 gastric carcinoma samples, gene expression data. Out of 29 established markers, higher expression of BECN1 (HR = 0.68, p = 1.5E-05), CASP3 (HR = 0.5, p = 6E-14), COX2 (HR = 0.72, p = 0.0013), CTGF (HR = 0.72, p = 0.00051), CTNNB1 (HR = 0.47, p = 4.3E-15), MET (HR = 0.63, p = 1.3E-05), and SIRT1 (HR = 0.64, p = 2.2E-07) correlated to longer OS. Higher expression of BIRC5 (HR = 1.45, p = 1E-04), CNTN1 (HR = 1.44, p = 3.5E- 05), EGFR (HR = 1.86, p = 8.5E-11), ERCC1 (HR = 1.36, p = 0.0012), HER2 (HR = 1.41, p = 0.00011), MMP2 (HR = 1.78, p = 2.6E-09), PFKB4 (HR = 1.56, p = 3.2E-07), SPHK1 (HR = 1.61, p = 3.1E-06), SP1 (HR = 1.45, p = 1.6E-05), TIMP1 (HR = 1.92, p = 2.2E- 10) and VEGF (HR = 1.53, p = 5.7E-06) were predictive for poor OS.

MATERIALS AND METHODS

We integrated samples of three major cancer research centers (Berlin, Bethesda and Melbourne datasets) and publicly available datasets with available follow-up data to form a single integrated database. Subsequently, we performed a literature search for prognostic markers in gastric carcinomas (PubMed, 2012–2015) and re-validated their findings predicting first progression (FP) and overall survival (OS) using uni- and multivariate Cox proportional hazards regression analysis.

Conclusions

The major advantage of our analysis is that we evaluated all genes in the same set of patients thereby making direct comparison of the markers feasible. The best performing genes include BIRC5, CASP3, CTNNB1, TIMP-1, MMP-2, SIRT, and VEGF.

SIRT1 in Secretory Organ Cancer

Mammalian silent information regulator 1 (SIRT1) is reported to play a role in cancers of the secretory organs, including thyroid, pancreatic endocrine, and ovarian tumors [1, 2, 3, 4]. A recent meta-analysis conducted on 37 selected studies of human cancers analyzed the correlations of overall survival (OS), disease-free survival (DFS) and relapse-free survival (RFS) with SIRT1 expression [5]. This study reported that SIRT1 overexpression was associated with a worse OS in liver and lung cancers, while it was not correlated with OS in breast cancer, colorectal cancer, or gastric carcinoma. Collectively, the meta-analysis revealed that an unfavorable OS was associated with SIRT1 expression for solid malignancies. Given the growing importance of this class of lysine/histone deacetylases in human endocrine malignancies, a rational and focused literature assessment is desirable in light of future clinical translations.

Promotion of autophagosome–lysosome fusion via salvianolic acid A-mediated SIRT1 up-regulation ameliorates alcoholic liver disease

Autophagosome and lysosome fusion was restored by salvianolic acid A-mediated SIRT1 up-regulation and protected against chronic ethanol-induced liver injury.