SIRT1 activation enhances HDAC inhibition-mediated upregulation of GADD45G by repressing the binding of NF-κB/STAT3 complex to its promoter in malignant lymphoid cells

Structure-based molecular docking and molecular dynamics simulations study for the identification of dipeptidyl peptidase 4 inhibitors in type 2 diabetes

Inhibition of dipeptidyl peptidase-4 (DPP4) activity has emerged as a promising therapeutic approach for the treatment of type 2 diabetes mellitus (T2DM). Bioinformatics-driven approaches have emerged as crucial tools in drug discovery. Molecular docking and molecular dynamics (MD) simulations are effective tools in drug discovery, as they reduce the time and cost associated with experimental screening. In this study, we employed structure-assisted in-silico methods, including molecular docking and MD simulations, to identify SRT2183, a small molecule that may potentially inhibit the activity of DPP4 enzyme. The interaction between the small molecule "SRT2183" and DPP4 exhibited a binding affinity of -9.9 Kcal/Mol, leading to the formation of hydrogen bonds with the amino acid residues MET348, SER376, and THR351 of DPP4. The MD simulations over a period of 100 ns indicated stable protein-ligand interactions, with no significant conformational rearrangements observed within the simulated timeframe. In conclusion, our results suggest that the small molecule SRT2183 may have the potential to inhibit the DPP4 enzyme and pave the way for the therapeutics of T2DM.Communicated by Ramaswamy H. Sarma.

Targeting sirtuins for cancer therapy: epigenetics modifications and beyond

Sirtuins (SIRTs) are well-known as nicotinic adenine dinucleotide+(NAD+)-dependent histone deacetylases, which are important epigenetic enzymes consisting of seven family members (SIRT1-7). Of note, SIRT1 and SIRT2 are distributed in the nucleus and cytoplasm, while SIRT3, SIRT4 and SIRT5 are localized in the mitochondria. SIRT6 and SIRT7 are distributed in the nucleus. SIRTs catalyze the deacetylation of various substrate proteins, thereby modulating numerous biological processes, including transcription, DNA repair and genome stability, metabolism, and signal transduction. Notably, accumulating evidence has recently underscored the multi-faceted roles of SIRTs in both the suppression and progression of various types of human cancers. Crucially, SIRTs have been emerging as promising therapeutic targets for cancer therapy. Thus, in this review, we not only present an overview of the molecular structure and function of SIRTs, but elucidate their intricate associations with oncogenesis. Additionally, we discuss the current landscape of small-molecule activators and inhibitors targeting SIRTs in the contexts of cancer and further elaborate their combination therapies, especially highlighting their prospective utility for future cancer drug development.

Gadd45g insufficiency drives the pathogenesis of myeloproliferative neoplasms

Despite the identification of driver mutations leading to the initiation of myeloproliferative neoplasms (MPNs), the molecular pathogenesis of MPNs remains incompletely understood. Here, we demonstrate that growth arrest and DNA damage inducible gamma (GADD45g) is expressed at significantly lower levels in patients with MPNs, and JAK2V617F mutation and histone deacetylation contribute to its reduced expression. Downregulation of GADD45g plays a tumor-promoting role in human MPN cells. Gadd45g insufficiency in the murine hematopoietic system alone leads to significantly enhanced growth and self-renewal capacity of myeloid-biased hematopoietic stem cells, and the development of phenotypes resembling MPNs. Mechanistically, the pathogenic role of GADD45g insufficiency is mediated through a cascade of activations of RAC2, PAK1 and PI3K-AKT signaling pathways. These data characterize GADD45g deficiency as a novel pathogenic factor in MPNs.

Downregulation of SIRT1 and GADD45G genes and left atrial fibrosis induced by right ventricular dependent pacing in a complete atrioventricular block pig model

The molecular and genetic mechanisms underlying left atrial (LA) enlargement and atrial fibrosis following right ventricular (RV) dependent pacing remain unclear. Our objective was to investigate genetic expressions in the LA of pigs subjected to RV pacing for atrioventricular block (AVB), as well as to identify the differential gene expressions affected by biventricular (BiV) pacing. We established an AVB pig model and divided the subjects into three groups: a sham control group, an RV pacing group, and a BiV pacing group. Differential expression genes (DEGs) analyses conducted through next-generation sequencing (NGS) and enrichment analyses were employed to identify genes with altered expression in the LA myocardium. The RV pacing group showed a significant increase in extracellular fibrosis in the LA myocardium compared to the control group. NGS analysis revealed suppressed expression of the sirtuin signaling pathway in the RV pacing group. Among the DEGs within this pathway, GADD45G was found to be downregulated in the RV pacing group and upregulated in the BiV pacing group. Remarkably, the BiV pacing group exhibited elevated levels of GADD45G protein. In our study, we observed significant downregulation of SIRT1 and GADD45G genes, which are associated with the sirtuin signaling pathway, in the LA myocardium of the RV pacing group when compared to the control group. Moreover, these genes, which were downregulated in the RV pacing group, displayed a noteworthy upregulation in the BiV pacing group when compared to the RV pacing group.

OR11H1 Missense Variant Confers the Susceptibility to Vogt-Koyanagi-Harada Disease by Mediating Gadd45g Expression

Vogt-Koyanagi-Harada (VKH) disease is a severe autoimmune disease. Herein, whole-exome sequencing (WES) study are performed on 2,573 controls and 229 VKH patients with follow-up next-generation sequencing (NGS) in a collection of 2,380 controls and 2,278 VKH patients. A rare c.188T>C (p Val63Ala) variant in the olfactory receptor 11H1 (OR11H1) gene is found to be significantly associated with VKH disease (rs71235604, Pcombined = 7.83 × 10-30 , odds ratio = 3.12). Functional study showes that OR11H1-A63 significantly increased inflammatory factors production and exacerbated barrier function damage. Further studies using RNA-sequencing find that OR11H1-A63 markedly increased growth arrest and DNA-damage-inducible gamma (GADD45G) expression. Moreover, OR11H1-A63 activates the MAPK and NF-κB pathways, and accelerates inflammatory cascades. In addition, inhibiting GADD45G alleviates inflammatory factor secretion, likely due to the regulatory effect of GADD45G on the MAPK and NF-κB pathways. Collectively, this study suggests that the OR11H1-A63 missense mutation may increase susceptibility to VKH disease in a GADD45G-dependent manner.

Ameliorative effects of androstenediol against acetic acid-induced colitis in male wistar rats via inhibiting TLR4-mediated PI3K/Akt and NF-κB pathways through estrogen receptor β activation

5-androstenediol (ADIOL) functions as a selective estrogen receptor β (ERβ) ligand with a protective effect against many diseases. So, we conducted a novel insight into its role in acetic acid (AA)-induced colitis and investigated its effect on TLR4-Mediated PI3K/Akt and NF-κB Pathways and the potential role of ERβ as contributing mechanisms.

METHODS

Rats were randomized into 5 Groups; Control, Colitis, Colitis + mesalazine (MLZ), Colitis + ADIOL, and Colitis + ADIOL + PHTPP (ER-β antagonist). The colitis was induced through a rectal enema of acetic acid (AA) on the 8th day. At the end of treatment, colons were collected for macroscopic assessment. Tissue levels of malondialdehyde (MDA), superoxide dismutase (SOD), nuclear factor kappa b (NF-κB), toll-like receptor (TLR4), and phosphorylated Protein kinase B (pAKT) were measured. Besides, Gene expression of interleukin-1beta (IL-1β), metalloproteases 9 (Mmp9), inositol 3 phosphate kinase (PI3K), Neutrophil gelatinase-associated lipocalin (NGAL), ERβ and NLRP6 were assessed. Histopathological and immunohistochemical studies were also investigated.

RESULTS

Compared to the untreated AA group, the disease activity index (DAI) and macroscopic assessment indicators significantly decreased with ADIOL injections. Indeed, ADIOL significantly decreased colonic tissue levels of MDA, TLR4, pAKT, and NF-κB immunostainig while increased SOD activity and β catenin immunostainig. ADIOL mitigated the high genetic expressions of IL1β, NGAL, MMP9, and PI3K while increased ERβ and NLRP6 gene expression. Also, the pathological changes detected in AA groups were markedly ameliorated with ADIOL. The specific ERβ antagonist, PHTPP, largely diminished these protective effects of ADIOL.

CONCLUSION

ADIOL could be beneficial against AA-induced colitis mostly through activating ERβ.

Berries vs. Disease: Revenge of the Phytochemicals

Secondary metabolites and phytochemicals in plant-based diets are known to possess properties that inhibit the development of several diseases including a variety of cancers of the aerodigestive tract. Berries are currently of high interest to researchers due to their high dietary source of phytochemicals. Black raspberries (BRB), Rubus occidentalis, are of special interest due to their rich and diverse composition of phytochemicals. In this review, we present the most up-to-date preclinical and clinical data involving berries and their phytochemicals in the chemoprevention of a variety of cancers and diseases. BRBs possess a variety of health benefits including anti-proliferative properties, anti-inflammatory activity, activation of pro-cell-death pathways, modulation of the immune response, microbiome modulation, reduction in oxidative stress, and many more. However, little has been done in both preclinical and clinical settings on the effects of BRB administration in combination with other cancer therapies currently available for patients. With the high potential for BRBs as chemopreventive agents, there is a need to investigate their potential in combination with other treatments to improve therapeutic efficacy.

A pharmacological review on SIRT 1 and SIRT 2 proteins, activators, and inhibitors: Call for further research

Sirtuins or Sir (Silent information regulator) are NAD⁺-dependent enzymes playing an important part in the pathogenesis and treatment of various disorders. They have ubiquitously expressed protein deacetylases. They are implicated in several cellular activities like DNA repair, cellular metabolism, mitochondrial function, and inflammation. Deletion of sirtuin protein, SIRT1 in the organs like brain, heart, liver and pancreas can cause inflammation and increases the level of free radical ions causing oxidative stress. Inflammation and oxidative stress are closely associated with pathophysiological events in many chronic diseases, like diabetes, cancer, cardiovascular, osteoporosis, and neurodegenerative diseases. Modulation of SIRT1 gene expression might help in preventing the progression of chronic diseases related to the brain, heart, liver, and pancreas. SIRT2 proteins play an essential role in tumorigenesis, including tumor-suppressing and tumor-promoting functions. Sirtuin activators are molecules that upregulate the activity of Sirtuins in the body. Their multifaceted uses have surprised the global scientific community. They are found to control obesity, lower cardiac risks, battle cancer, etc. This article provides an update on the pharmacological effect of SIRT1 and SIRT 2 proteins, their activators and inhibitors, and their molecular mechanism. It provides novel insights for future research in targeted therapy and drug development.

Trichodermin inhibits the growth of oral cancer through apoptosis-induced mitochondrial dysfunction and HDAC-2-mediated signaling

Trichodermin (TCD), a trichothecene first isolated from marine Trichoderma viride, is an inhibitor of eukaryotic protein synthesis. However, the potential effects of TCD on human oral squamous cell carcinoma (OSCC) cells and the underlying molecular mechanisms remain unknown. In this study, the exposure of OSCC cells (Ca922 and HSC-3 cells) to TCD suppressed cell proliferation assessed using MTT assays and colony formation assays. TCD inhibited the migration and invasion of OSCC cells (Ca922 and HSC-3 cells) through the downregulation of matrix metalloproteinase 9. After treatment of OSCC cells with TCD, the G2/M phase was arrested, caspase-related apoptosis (cleaved caspase-3 and PARP expression) was induced, and the protein level of x-linked inhibitor of apoptosis was reduced. Meanwhile, the TCD-induced cell death was reversed by the pan-caspase inhibitor Z-VAD-FMK. Furthermore, TCD diminished mitochondrial membrane potential, mitochondrial oxidative phosphorylation and glycolytic function in OSCC cells. In addition, TCD decreased the levels of histone deacetylase 2 (HDAC-2) and downstream signaling proteins, including phosphorylated STAT3 and NF-κB. Finally, TCD significantly suppressed tumor growth in a zebrafish OSCC xenotransplantation model. Overall, this evidence demonstrates that TCD is a novel promising strategy for the treatment of OSCCs.

Inflammatory-miR-301a circuitry drives mTOR and Stat3-dependent PSC activation in chronic pancreatitis and PanIN

Activated pancreatic stellate cells (PSCs) are the main cells involved in chronic pancreatitis and pancreatic intraepithelial neoplasia lesion (PanIN). Fine-tuning the precise molecular targets in PSC activation might help the development of PSC-specific therapeutic strategies to tackle progression of pancreatic cancer-related fibrosis. miR-301a is a pro-inflammatory microRNA known to be activated by multiple inflammatory factors in the tumor stroma. Here, we show that miR-301a is highly expressed in activated PSCs in mice, sustained tissue fibrosis in caerulein-induced chronic pancreatitis, and accelerated PanIN formation. Genetic ablation of miR-301a reduced pancreatic fibrosis in mouse models with chronic pancreatitis and PanIN. Cell proliferation and activation of PSCs was inhibited by downregulation of miR-301a via two of its targets, Tsc1 and Gadd45g. Moreover, aberrant PSC expression of miR-301a and Gadd45g restricted the interplay between PSCs and pancreatic cancer cells in tumorigenesis. Our findings suggest that miR-301a activates two major cell proliferation pathways, Tsc1/mTOR and Gadd45g/Stat3, in vivo, to facilitate development of inflammatory-induced PanIN and maintenance of PSC activation and desmoplasia in pancreatic cancer.

Genome-wide CRISPR/Cas9 screening identifies determinant of panobinostat sensitivity in acute lymphoblastic leukemia

Genome-wide CRISPR/Cas9 screening in the ALL cell line identified mitochondrial activity as the driver of panobinostat resistance.

SIRT1 expression sensitized ALL to panobinostat through activating mitochondrial activity and the mitochondria-related apoptosis pathway.

Epigenetic alterations, including histone acetylation, contribute to the malignant transformation of hematopoietic cells and disease progression, as well as the emergence of chemotherapy resistance. Targeting histone acetylation provides new strategies for the treatment of cancers. As a pan-histone deacetylase inhibitor, panobinostat has been approved by the US Food and Drug Administration for the treatment of multiple myeloma and has shown promising antileukemia effects in acute lymphoblastic leukemia (ALL). However, the underlying drug resistance mechanism in ALL remains largely unknown. Using genome-wide Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/CRISPR-associated (Cas)9 (CRISPR/Cas9) screening, we identified mitochondrial activity as the driver of panobinostat resistance in ALL. Mechanistically, ectopic SIRT1 expression activated mitochondrial activity and sensitized ALL to panobinostat through activating mitochondria-related apoptosis pathway. Meanwhile, the transcription level of SIRT1 was significantly associated with panobinostat sensitivity across diverse tumor types and thus could be a potential biomarker of panobinostat response in cancers. Our data suggest that patients with higher SIRT1 expression in cancer cells might benefit from panobinostat treatment, supporting the implementation of combinatorial therapy with SIRT1 or mitochondrial activators to overcome panobinostat resistance.

Dietary Hermetia illucens Larvae Meal Improves Growth Performance and Intestinal Barrier Function of Weaned Pigs Under the Environment of Enterotoxigenic Escherichia coli K88

The aim of this study was to evaluate the effect of Hermetia illucens larvae meal (HI) on the growth performance and intestinal barrier function of weaned pigs. To achieve this, 72 weaned pigs [28-day-old, 8.44 ± 0.04 kg body weight (BW)] were randomly assigned to three dietary treatments: basal diet (negative control, NC), zinc oxide-supplemented diet (positive control, PC), and HI-supplemented diet [100% replacement of fishmeal (FM), HI], for 28 days in the presence of enterotoxigenic Escherichia coli (ETEC). The results showed that HI and PC increased (p < 0.05) the average daily gain (ADG) and average daily feed intake (ADFI) of weaned pigs from day 1 to 14, and decreased diarrhea incidence from day 1 to 28. Additionally, HI increased (p < 0.05) claudin-1, occludin, mucin-1 (MUC-1), and MUC-2 expression, goblet cell number, and secretory immunoglobulin A (sIgA) concentration in the intestine of weaned pigs. Compared with NC, HI downregulated (p < 0.05) interleukin-1β (IL-1β) and IL-8 expression, and upregulated IL-10, transforming growth factor-β (TGF-β), antimicrobial peptide [porcine β defensin 1 (pBD1), pBD2, protegrin 1-5 (PG1-5)] expression in the jejunum or ileum. Moreover, HI decreased (p < 0.05) toll-like receptor 2 (TLR2), phosphorylated nuclear factor-κB (p-NF-κB), and phosphorylated mitogen-activated protein kinase (p-MAPK) expression, and increased sirtuin 1 (SIRT1) expression in the ileum. Additionally, HI increased histone deacetylase 3 (HDAC3) expression and acetylation of histone 3 lysine 27 (acH3k27) in the ileum. Furthermore, HI positively influenced the intestinal microbiota composition and diversity of weaned pigs and increased (p < 0.05) butyrate and valerate concentrations. Overall, dietary HI improved growth performance and intestinal barrier function, as well as regulated histone acetylation and TLR2-NF-κB/MAPK signaling pathways in weaned pigs.

Targeting Histone Deacetylases: Opportunities for Cancer Treatment and Chemoprevention

The dysregulation of gene expression is a critical event involved in all steps of tumorigenesis. Aberrant histone and non-histone acetylation modifications of gene expression due to the abnormal activation of histone deacetylases (HDAC) have been reported in hematologic and solid types of cancer. In this sense, the cancer-associated epigenetic alterations are promising targets for anticancer therapy and chemoprevention. HDAC inhibitors (HDACi) induce histone hyperacetylation within target proteins, altering cell cycle and proliferation, cell differentiation, and the regulation of cell death programs. Over the last three decades, an increasing number of synthetic and naturally derived compounds, such as dietary-derived products, have been demonstrated to act as HDACi and have provided biological and molecular insights with regard to the role of HDAC in cancer. The first part of this review is focused on the biological roles of the Zinc-dependent HDAC family in malignant diseases. Accordingly, the small-molecules and natural products such as HDACi are described in terms of cancer therapy and chemoprevention. Furthermore, structural considerations are included to improve the HDACi selectivity and combinatory potential with other specific targeting agents in bifunctional inhibitors and proteolysis targeting chimeras. Additionally, clinical trials that combine HDACi with current therapies are discussed, which may open new avenues in terms of the feasibility of HDACi’s future clinical applications in precision cancer therapies.

TNF-α/TNFR1 regulates the polarization of Kupffer cells to mediate trichloroethylene-induced liver injury

We have previously shown trichloroethylene (TCE) induced immune liver injury, and TNF-α/TNFR1 pathway as a probably mechanism underlying the immune damage, but the pathogenic mechanism is still unclear. The study aims to investigate whether TNF-α and its receptors regulate Kupffer cell polarization and downstream inflammation signaling pathways during TCE sensitization, to clarify the mechanism of TCE-mediated immune liver injury. 6-8 weeks old SPF BALB/c female mice were used to establish a TCE sensitization model. We found that in the TCE sensitization positive group, liver injury was aggravated, Kupffer cells activated and polarized to M1 type. The expression of M1 Kupffer cell marker proteins CD11c and CD16/32 increased in the TCE positive group, so did TNF-α and TNFR1 in liver. The expression of P-IKK protein, PP65 protein and P-STAT3 protein increased in the TCE sensitization positive group, and the downstream inflammatory factors IL-1β and IL-6 also increased in the TCE sensitization positive group. After using the TNFR1 inhibitor R7050, we found that M1 Kupffer cell polarization, TNF-α expression, signal pathway expression and inflammatory factors IL-1β and IL-6 expression declined, and the liver damage relieved. Briefly, the use of R7050 to inhibit TNF-α/TNFR1 changing the polarization of liver M1 Kupffer cell, thereby inhibiting the activation of related downstream signaling pathways and reducing the secretion of inflammatory factors. TNF-α/TNFR1 regulates the polarization of M1 Kupffer cells inflammatory play an important role in liver immune damage.

Deacetylation of Transcription Factors in Carcinogenesis

Reversible Nε-lysine acetylation/deacetylation is one of the most common post-translational modifications (PTM) of histones and non-histone proteins that is regulated by histone acetyltransferases (HATs) and histone deacetylases (HDACs). This epigenetic process is highly involved in carcinogenesis, affecting histone and non-histone proteins' properties and their biological functions. Some of the transcription factors, including tumor suppressors and oncoproteins, undergo this modification altering different cell signaling pathways. HDACs deacetylate their targets, which leads to either the upregulation or downregulation of proteins involved in the regulation of cell cycle and apoptosis, ultimately influencing tumor growth, invasion, and drug resistance. Therefore, epigenetic modifications are of great clinical importance and may constitute a new therapeutic target in cancer treatment. This review is aimed to present the significance of HDACs in carcinogenesis through their influence on functions of transcription factors, and therefore regulation of different signaling pathways, cancer progression, and metastasis.

GADD45g acts as a novel tumor suppressor and its activation confers new combination regimens for the treatment of AML

Acute myeloid leukemia (AML) is an aggressive hematopoietic malignancy for which there is an unmet need for novel treatment strategies. Here, we characterize the growth arrest and DNA damage-inducible gene gamma (GADD45g) as a novel tumor suppressor in AML. We show that GADD45g is preferentially silenced in AML, especially in AML with FMS-like tyrosine kinase 3-internal tandem duplication (FLT3-ITD) mutations and mixed-lineage leukemia (MLL)-rearrangements, and reduced expression of GADD45g is correlated with poor prognosis in AML patients. Upregulation of GADD45g impairs homologous recombination (HR) DNA repair, leading to DNA damage accumulation, and dramatically induces apoptosis, differentiation, growth arrest and increases sensitivity of AML cells to chemotherapeutic drugs, without affecting normal cells. In addition, GADD45g is epigenetically silenced by histone deacetylation in AML, and its expression is further downregulated by oncogenes FLT3-ITD and MLL-AF9 in patients carrying these genetic abnormalities. Combination of histone deacetylase 1/2 inhibitor Romidepsin with FLT3 tyrosine kinase inhibitor AC220 or bromodomain inhibitor JQ1 exert synergistic anti-leukemic effects on FLT3-ITD+ and MLL-AF9+ AML, respectively, by dually activating GADD45g. These findings uncover hitherto unreported evidence for the selective anti-leukemia role of GADD45g and provide novel strategies for the treatment of FLT3-ITD+ and MLL-AF9+ AML.

Circadian clock modulating small molecules repurposing as inhibitors of SARS-CoV-2 Mpro for pharmacological interventions in COVID-19 pandemic

The COVID-19 pandemic caused by SARS-CoV-2 is a global health emergency warranting the development of targeted treatment. The main protease M^pro is considered as a key drug target in coronavirus infections because of its vital role in the proteolytic processing of two essential polyproteins required for the replication and transcription of viral RNA. Targeting and inhibiting the M^pro activity represents a valid approach to prevent the SARS-CoV-2 replication and spread. Based on the structure-assisted drug designing, here we report a circadian clock-modulating small molecule “SRT2183” as a potent inhibitor of M^pro to block the replication of SARS-CoV-2. The findings are expected to pave the way for the development of therapeutics for COVID-19.

SRT2183 impairs ovarian cancer by facilitating autophagy

The 5-year survival rate of ovarian cancer patients is only 47%, and developing novel drugs for ovarian cancer is needed. Herein, we evaluated if and how SRT2183, a sirtuin-1 activator, impairs the ovarian cancer cells. OVCAR-3 and A2780 cells were treated with SRT2183. Cell viability was measured by cell counting kit-8 assay and clonogenic assay. Apoptosis was determined by flow cytometry with Annexin V and propidium iodide. The level of autophagy was evaluated by western blot and immunofluorescence. The activities of AKT/mTOR/70s6k and MAPK signaling pathway were measured by immunoblot. SRT2183 inhibited the growth of ovarian cancer cells, increased the accumulation of BAX, cleaved-caspase 3 and cleaved-PARP, and decreased the level of anti-apoptotic Bcl-2 and Mcl-1. SRT2183 increased the LC3II level, and enhanced the degradation of p62/SQSTM1. SRT2183 increased the formation of GFP-LC3 puncta and induced the maturation of autophagosome. Interestingly, knockdown of autophagy related 5 and 7 significantly impaired the anti-carcinoma activity of SRT2183, implying that SRT2183 impaired the ovarian cancer cells by inducing autophagy. SRT2183 decreased the accumulation of p-Akt, p-mTOR and p-70s6k, and activated the p38 MAPK signaling pathway. This indicated that Akt/mTOR/70s6k and p38 MAPK signaling pathway might be involved in the SRT2183-mediated autophagy and apoptosis.

Hypoxia-induced NAD+ interventions promote tumor survival and metastasis by regulating mitochondrial dynamics

Hypoxia, an important feature of the tumor microenvironment, is responsible for the chemo-resistance and metastasis of malignant solid tumors. Recent studies indicated that mitochondria undergo morphological transitions as an adaptive response to maintain self-stability and connectivity under hypoxic conditions. NAD⁺ may not only provide reducing equivalents for biosynthetic reactions and in determining energy production, but also functions as a signaling molecule in mitochondrial dynamics regulation. In this review, we describe the upregulated KDAC deacetylase expression in the mitochondria and cytoplasm of tumor cells that results from sensing the changes in NAD⁺ to control mitochondrial dynamics and distribution, which is responsible for survival and metastasis in hypoxia.

Genome-Protecting Compounds as Potential Geroprotectors

Throughout life, organisms are exposed to various exogenous and endogenous factors that cause DNA damages and somatic mutations provoking genomic instability. At a young age, compensatory mechanisms of genome protection are activated to prevent phenotypic and functional changes. However, the increasing stress and age-related deterioration in the functioning of these mechanisms result in damage accumulation, overcoming the functional threshold. This leads to aging and the development of age-related diseases. There are several ways to counteract these changes: 1) prevention of DNA damage through stimulation of antioxidant and detoxification systems, as well as transition metal chelation; 2) regulation of DNA methylation, chromatin structure, non-coding RNA activity and prevention of nuclear architecture alterations; 3) improving DNA damage response and repair; 4) selective removal of damaged non-functional and senescent cells. In the article, we have reviewed data about the effects of various trace elements, vitamins, polyphenols, terpenes, and other phytochemicals, as well as a number of synthetic pharmacological substances in these ways. Most of the compounds demonstrate the geroprotective potential and increase the lifespan in model organisms. However, their genome-protecting effects are non-selective and often are conditioned by hormesis. Consequently, the development of selective drugs targeting genome protection is an advanced direction.

The extracellular sulfatase SULF2 promotes liver tumorigenesis by stimulating assembly of a promoter-looping GLI1-STAT3 transcriptional complex

The expression of the extracellular sulfatase SULF2 has been associated with increased hepatocellular carcinoma (HCC) growth and poor patient survival. However, the molecular mechanisms underlying SULF2-associated tumor growth remain unclear. To address this gap, here we developed a transgenic mouse overexpressing Sulf2 in hepatocytes under the control of the transthyretin promoter. In this model, Sulf2 overexpression potentiated diethylnitrosamine-induced HCC. Further analysis indicated that the transcription factor GLI family zinc finger 1 (GLI1) mediates Sulf2 expression during HCC development. A cross of the Sulf2-overexpressing with Gli1-knockout mice revealed that Gli1 inactivation impairs SULF2-induced HCC. Transcriptomic analysis revealed that Sulf2 overexpression is associated with signal transducer and activator of transcription 3 (STAT3)-specific gene signatures. Interestingly, the Gli1 knockout abrogated SULF2-mediated induction of several STAT3 target genes, including suppressor of cytokine signaling 2/3 (Socs2/3); Pim-1 proto-oncogene, Ser/Thr kinase (Pim1); and Fms-related tyrosine kinase 4 (Flt4). Human orthologs were similarly regulated by SULF2, dependent on intact GLI1 and STAT3 functions in HCC cells. SULF2 overexpression promoted a GLI1-STAT3 interaction and increased GLI1 and STAT3 enrichment at the promoters of their target genes. Interestingly, the SULF2 overexpression resulted in GLI1 enrichment at select STAT3 consensus sites, and vice versa. siRNA-mediated STAT3 or GLI1 knockdown reduced promoter binding of GLI1 and STAT3, respectively. Finally, chromatin-capture PCR confirmed long-range co-regulation of SOCS2 and FLT3 through changes in promoter conformation. These findings define a mechanism whereby SULF2 drives HCC by stimulating formation of a GLI1-STAT3 transcriptional complex.

Drivers of topoisomerase II poisoning mimic and complement cytotoxicity in AML cells

Recently approved cancer drugs remain out-of-reach to most patients due to prohibitive costs and only few produce clinically meaningful benefits. An untapped alternative is to enhance the efficacy and safety of existing cancer drugs. We hypothesized that the response to topoisomerase II poisons, a very successful group of cancer drugs, can be improved by considering treatment-associated transcript levels. To this end, we analyzed transcriptomes from Acute Myeloid Leukemia (AML) cell lines treated with the topoisomerase II poison etoposide. Using complementary criteria of co-regulation within networks and of essentiality for cell survival, we identified and functionally confirmed 11 druggable drivers of etoposide cytotoxicity. Drivers with pre-treatment expression predicting etoposide response (e.g., PARP9) generally synergized with etoposide. Drivers repressed by etoposide (e.g., PLK1) displayed standalone cytotoxicity. Drivers, whose modulation evoked etoposide-like gene expression changes (e.g., mTOR), were cytotoxic both alone and in combination with etoposide. In summary, both pre-treatment gene expression and treatment-driven changes contribute to the cell killing effect of etoposide. Such targets can be tweaked to enhance the efficacy of etoposide. This strategy can be used to identify combination partners or even replacements for other classical anticancer drugs, especially those interfering with DNA integrity and transcription.

Sirtuin1 activator SRT2183 suppresses glioma cell growth involving activation of endoplasmic reticulum stress pathway

Background

Glioblastoma (GBM) is an extremely deadly form of brain cancer with limited treatment options and thus novel therapeutic modalities are necessary. Histone deacetylase inhibitors (HDACi) have demonstrated clinical and preclinical activities against GBM. (Silent mating type information regulation 2 homolog, Sirt1) abbreviated as Sirtuin 1, has been implicated in GBM. We explored the activity of the Sirt1 activator SRT2183 in glioma cell lines in terms of biological response.

Methods

The effects of SRT2183 on glioma cell growth and neurosphere survival were evaluated in vitro using the CCK-8, clonogenic and neurosphere assays, respectively. Glioma cell cycle arrest and apoptosis were determined by flow cytometry. SRT2183-induced autophagy was investigated by detection of GFP-microtubule-associated protein 1 light chain 3 (GFP-LC3) puncta, conversion of the nonlipidated form of LC3 (LC3-I) to the phosphatidylethanolamine-conjugated form (LC3-II). Acetylation of STAT3 and NF-κB in SRT2183-treated glioma cells was examined using immunoprecipitation. The expression levels of anti-apoptotic proteins were assayed by immunoblotting.

Results

SRT2183 suppressed glioma cell growth and destroyed neurospheres in vitro. Furthermore, SRT2183 induced glioma cell cycle arrest and apoptosis, accompanying by upregulation of the pro-apoptotic Bim and downregulation of Bcl-2 and Bcl-xL. Notably, ER stress was triggered in glioma cells upon exposure to SRT2183 while the pre-exposure to 4-PBA, an ER stress inhibitor, significantly antagonized SRT2183-mediated growth inhibition in glioma cells. In addition, SRT2183 induced autophagy in glioma cells and pharmacological modulation of autophagy appeared not to affect SRT2183-inhibited cell growth. Of interest, the acetylation and phosphorylation of p65 NF-κB and STAT3 in glioma cells were differentially affected by SRT2183.

Conclusions

Our data suggest the ER stress pathway is involved in SRT2183-mediated growth inhibition in glioma. Further investigation in vivo is needed to consolidate the data.

Role of Natural Products in Modulating Histone Deacetylases in Cancer

Histone deacetylases (HDACs) are enzymes that can control transcription by modifying chromatin conformation, molecular interactions between the DNA and the proteins as well as the histone tail, through the catalysis of the acetyl functional sites removal of proteins from the lysine residues. Also, HDACs have been implicated in the post transcriptional process through the regulation of the proteins acetylation, and it has been found that HDAC inhibitors (HDACi) constitute a promising class of pharmacological drugs to treat various chronic diseases, including cancer. Indeed, it has been demonstrated that in several cancers, elevated HDAC enzyme activities may be associated with aberrant proliferation, survival and metastasis. Hence, the discovery and development of novel HDACi from natural products, which are known to affect the activation of various oncogenic molecules, has attracted significant attention over the last decade. This review will briefly emphasize the potential of natural products in modifying HDAC activity and thereby attenuating initiation, progression and promotion of tumors.

A Possible Reason to Induce Acute Graft-vs.-Host Disease After Hematopoietic Stem Cell Transplantation: Lack of Sirtuin-1 in CD4+ T Cells

Sirtuin 1 (SIRT1) is a critical suppressor of T cell immunity. However, whether SIRT1 is involved in the progression of acute graft-vs.-host disease (aGVHD) has still remained unclear. PI3K/Akt/mTOR pathway is a crucial element involved in the activation and functions of T cells. Over-activation of PI3K/Akt/mTOR signaling may be related to the occurrence of aGVHD. STAT3 activation requires phosphorylation and acetylation. A recent study showed that STAT3 hyperphosphorylation in CD4⁺ T cells may be a trigger of aGVHD. The role of the STAT3 acetylation in aGVHD pathogenesis is still unclear. The present study revealed that SIRT1 deficiency as a critical factor is involved in the excessive activation of mTOR pathway and upregulation of STAT3 acetylation and phosphorylation in CD4⁺ T cells from patients with aGVHD. Exorbitant activation of IL-1β signaling is the main reason for TAK1-dependent SIRT1 insufficiency. The findings of the present study might provide a new therapeutic target for treating aGVHD.

Combinational Proanthocyanidins and Resveratrol Synergistically Inhibit Human Breast Cancer Cells and Impact Epigenetic⁻Mediating Machinery

Breast cancer is the second most common cancer and the second leading cause of death from cancer among women in the United States (US). Cancer prevention and therapy through the use of phytochemicals that have epigenetic properties has gained considerable interest during the past few decades. Such dietary components include, but are not limited to, grape seed proanthocyanidins (GSPs) and resveratrol (Res), both of which are present in red wine. In this study, we report for the first time the synergistic effects of GSPs and Res on inhibiting MDA-MB-231 and MCF-7 human breast cancer cells. Our results of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays and clonogenic assays indicate that treatments with the combinations of GSPs and Res synergistically decreased cell viability and posttreatment cell proliferation in both cell lines. Additional analyses show that treatments with GSPs and Res in combination synergistically induced apoptosis in MDA-MB-231 cells by upregulating Bax expression and down-regulating Bcl-2 expression. DNA methyltransferase (DNMT) activity and histone deacetylase (HDAC) activity were greatly reduced in MDA-MB-231 and MCF-7 cells after treatments with GSPs and Res in combination. Collectively, our findings suggest that GSPs and Res synergistically inhibit human breast cancer cells through inducing apoptosis, as well as modulating DNA methylation and histone modifications.

1-Deoxynojirimycin (DNJ) Ameliorates Indomethacin-Induced Gastric Ulcer in Mice by Affecting NF-kappaB Signaling Pathway

Gastric ulcer (GU) is a main threat to public health. 1-Deoxynojirimycin (DNJ) has antioxidant and anti-inflammatory properties and may prevent GU but related mechanism remains unclear. DNJ was extracted from the supernatants of Bacillus subtilis by using ethanol and purified by using CM-Sepharose chromatography. A GU mouse model was induced by indomethacin. The functional role of DNJ in GU mice was explored by measuring the main molecules in the NF-KappaB pathway. After the model establishment, 40 GU mice were evenly assigned into five categories: IG (received vehicle control), LG (10 μg DNJ daily), MG (20 μg DNJ daily), HG (40 μg DNJ daily), and RG (0.5 mg ranitidine daily). Meanwhile, eight healthy mice were assigned as a control group (CG). After 1-month therapy, weight and gastric volume were investigated. The levels of serum inflammatory cytokines (IL-6 and TNF-α), antioxidant indices [superoxide dismutase (SOD), catalase (CAT), and reduced glutathione (GSH)], and oxidant biomarker malondialdehyde (MDA) were examined via ELISA. Meanwhile, inflammatory cytokine (IL-6 and TNF-α) levels, and key molecules (NF-κB p65), cyclooxygenase 1 (COX-1 and COX2) involved in NF-κB pathway, were analyzed by using Western Blot. COX-1 and COX-2 levels were further measured by immunohistochemistry. The effects of DNJ on gastric functions were explored by measuring the changes of Motilin (MOT), Substance P (SP), Somatostatin (SS), and Vasoactive intestinal peptide (VIP) in GU mouse models with ELISA Kits. The results indicated that DNJ prevented indomethacin-caused increase of gastric volume. DNJ improved histopathology of GU mice when compared with the mice from IG group (P < 0.05). DNJ consumption decreased the levels of IL-6 and TNF-α (P < 0.05). DNJ increased antioxidant indices of GU mice by improving the activities of SOD, CAT and reduced GSH, and reduced MDA levels (P < 0.05). DNJ increased the levels of prostaglandin E2, COX-1, COX2, and reduced the levels of and NF-κB p65 (P < 0.05). DNJ showed protection for gastric functions of GU mice by reducing the levels of MOT and SP, and increasing the levels of SS and VIP. DNJ treatment inactivates NF-κB signaling pathway, and increases anti-ulceration ability of the models.

Root Extract of Polygonum cuspidatum Siebold & Zucc. Ameliorates DSS-Induced Ulcerative Colitis by Affecting NF-kappaB Signaling Pathway in a Mouse Model via Synergistic Effects of Polydatin, Resveratrol, and Emodin

Background:Polygonum cuspidatum Siebold & Zucc. (PCS) has antibacterial properties and may prevent Ulcerative colitis (UC) but related molecular mechanism remains unknown. NF-κB signaling pathway is associated with inflammatory responses and its inactivation may be critical for effective therapy of UC.

Methods: UC mouse (C57BL/6J) model was established by using dextran sulfate sodium (DSS). The extract of PCS (PCSE) was prepared by using ethanol and its main ingredients were measured by HPLC. Thirty-two UC mice were evenly assigned into DG (received vehicle control), LG (0.1 g/kg PCSE daily), MG (0.2 g/kg PCSE daily) and HG (0.4 g/kg PCSE daily) groups. Meanwhile, 8 healthy mice were assigned as a control group (CG). Serum pharmacokinetics of PCS was measured by using HPLC. After 8-day treatment, weight, colon length and disease activity index (DAI) were measured. Inflammatory cytokines and oxidant biomarkers were measured by ELISA kits. The levels of cytokines, and key molecules in NF-κB pathway, were measured by using Western Blot. The effects of main ingredients of PCSE on cytokines and NF-κB signaling pathway were explored by using intestinal cells of a mouse UC model. The normality criterion was evaluated using the Saphiro–Wilk test. The quantitative variables were compared using the paired Student’s-t test.

Results: The main ingredients of PCSE were polydatin, resveratrol and emodin. Polydatin may be transformed into resveratrol in the intestine of the mice. PCSE prevented DSS-caused weight loss and colon length reduction, and improved histopathology of UC mice (P < 0.05). PCSE treatment increased the serum levels of IL-10 and reduced the levels of IL-1 beta, IL-6 and TNF-α (P < 0.05). PCSE increased the activities of SOD, CAT, GPX and reduced the level of MDA, BCL-2, beta-arrestin, NF-κB p65 and the activity of MPO (P < 0.05). The combination of polydatin, resveratrol or emodin, and or PCSE exhibited higher inhibitory activities for cytokines and NF-κB signaling related molecules than any one of the three ingredients with same concentration treatment.

Conclusion: Oral administration of PCSE suppressed NF-κB signaling pathway and exerts its anti-colitis effects via synergistic effects of polydatin, resveratrol or emodin.

Trichostatin A and Sirtinol Regulate the Expression and Nucleocytoplasmic Shuttling of Histone Deacetylases in All-Trans Retinoic Acid-Induced Differentiation of Neuroblastoma Cells

Neuroblastoma cell differentiation is a valuable model for studying therapeutic methods in neuroblastoma and the mechanisms of neuronal differentiation. Here, we used trichostatin A (TSA) and sirtinol, which are inhibitors of cHDACs and sirtuins, respectively, to show that classical histone deacetylases (cHDACs) and sirtuins (silent mating type information regulation 2 homolog; SIRTs) affect all-trans retinoic acid (ATRA)-induced differentiation of neuroblastoma cells. After first determining neurite elongation and expression levels of tyrosine hydroxylase and high size neurofilament as useful differentiation markers, we observed that TSA increased neuroblastoma cell differentiation, while sirtinol had the antagonistic effect of decreasing it. The changes were also associated with the nucleocytoplasmic shuttling of cHDACs and sirtuins. ATRA significantly decreased the nuclear to cytoplasmic ratio of SIRT1 and SIRT2.1, while sirtinol inhibited that of SIRT1, and TSA increased that of SIRT1 and SIRT2.1 during early differentiation. Moreover, the effect of the sirtinol-related signal was located upstream for cHDACs and sirtuins total expression, and downstream for their subcellular localization compared with that for the TSA-related signal. These results provide a mechanistic understanding of differentiation in neuroblastoma cells and indicate that cHDACs and sirtuins are critical therapeutic targets for neuroblastoma.

GADD45 family proteins suppress JNK signaling by targeting MKK7

Growth arrest and DNA damage-inducible 45 (GADD45) family genes encode related proteins, including GADD45α, GADD45β, and GADD45γ. In HeLa cells, expression of GADD45 members is differentially regulated under a variety of environmental conditions, but thermal and genotoxic stresses induce the expression of all genes. The heat shock response of GADD45β is mediated by the heat shock transcription factor 1 (HSF1), and GADD45β is necessary for heat stress survival. Heat and genotoxic stress-induced activation of c-Jun N-terminal kinase (JNK) is suppressed by the expression of GADD45 proteins. GADD45 proteins bind the JNK kinase mitogen-activated protein kinase kinase 7 (MKK7) and inhibit its activity, even under normal physiological conditions. Our findings indicate that GADD45 essentially suppresses the MKK7-JNK pathway and suggest that differentially expressed GADD45 family members fine-tune stress-inducible JNK activity.

Inflammatory factor TNF-α promotes the growth of breast cancer via the positive feedback loop of TNFR1/NF-κB (and/or p38)/p-STAT3/HBXIP/TNFR1

In the connection between inflammation and cancer development, tumor necrosis factor-alpha (TNF-α) contributes to the tumorigenesis. However, the underlying mechanism remains poorly understood. In this study, we report that TNF-α enhances the growth of breast cancer through up-regulation of oncoprotein hepatitis B X-interacting protein (HBXIP). Our data showed that the levels of TNF-α were positively related to those of HBXIP in clinical breast cancer tissues. Moreover, TNF-α could up-regulate HBXIP in breast cancer cells. Interestingly, silencing of TNF-α receptor 1 (TNFR1) blocked the effect of TNF-α on HBXIP. Mechanistically, we revealed that TNF-α could increase the activities of HBXIP promoter through activating transcriptional factor signal transducer and activator of transcription 3 (STAT3). In addition, nuclear factor kappa B (NF-κB) and/or p38 signaling increased the levels of p-STAT3 in the cells. Strikingly, HBXIP could also up-regulate TNFR1, forming a positive feedback loop of TNFR1/NF-κB (and/or p38)/p-STAT3/HBXIP/TNFR1. Notably, TNF-α was able to up-regulate TNFR1 through driving the loop. In function, we demonstrated that the knockdown of HBXIP remarkably abolished the growth of breast cancer mediated by TNF-α in vitro and in vivo. Thus, we conclude that TNF-α promotes the growth of breast cancer through the positive feedback loop of TNFR1/NF-κB (and/or p38)/p-STAT3/HBXIP/TNFR1.Our finding provides new insights into the mechanism by which TNF-α drives oncoprotein HBXIP in the development of breast cancer.

Histone deacetylase inhibitors enhance CD1d-dependent NKT cell responses to lymphoma

Histone deacetylases (HDACs) are a family of enzymes that influence expression of genes implicated in tumor initiation, progression, and anti-tumor responses. In addition to their canonical role in deacetylation of histones, HDACs regulate many non-canonical targets, such as Signal Transducer and Activator of Transcription 3 (STAT3). We hypothesize that tumors use epigenetic mechanisms to dysregulate CD1d-mediated antigen presentation, thereby impairing the ability of natural killer T (NKT) cells to recognize and destroy malignant cells. In this study, we pre-treated CD1d-expressing tumor cells with HDAC inhibitors (HDACi) and assessed CD1d-dependent NKT cell responses to mantle cell lymphoma (MCL). Pre-treatment with Trichostatin-A, a pan-HDACi, rapidly enhanced both CD1d- and MHC class II-mediated antigen presentation. Similarly, treatment of MCL cells with other HDACi resulted in enhanced CD1d-dependent NKT cell responses. The observed changes are due, at least in part, to an increase in both CD1D mRNA and CD1d cell surface expression. Mechanistically, we found that HDAC2 binds to the CD1D promoter. Knockdown of HDAC2 in tumor cells resulted in a significant increase in CD1d-mediated antigen presentation. In addition, treatment with HDACi inhibited STAT3 and STAT3-regulated inflammatory cytokine secretion by MCL cells. We demonstrated that MCL-secreted IL-10 inhibits CD1d-mediated antigen presentation and pre-treatment with TSA abrogates secretion of IL-10 by MCL. Taken together, our studies demonstrate the efficacy of HDACi in restoring anti-tumor responses to MCL through both cell-intrinsic and cell-extrinsic mechanisms and strongly implicate a role for HDACi in enhancing immune responses to cancer.

TG2 and NF-κB Signaling Coordinates the Survival of Mantle Cell Lymphoma Cells via IL6-Mediated Autophagy

Expression of the transglutaminase TG2 has been linked to constitutive activation of NF-κB and chemotherapy resistance in mantle cell lymphoma (MCL) cells. TG2 forms complexes with NF-κB components, but mechanistic insights that could be used to leverage therapeutic responses has been lacking. In the current study, we address this issue with the discovery of an unexpected role for TG2 in triggering autophagy in drug-resistant MCL cells through induction of IL6. CRISPR-mediated silencing of TG2 delayed apoptosis while overexpressing TG2 enhanced tumor progression. Under stress, TG2 and IL6 mediate enhanced autophagy formation to promote MCL cell survival. Interestingly, the autophagy product ATG5 involved in autophagosome elongation positively regulated TG2/NF-κB/IL6 signaling, suggesting a positive feedback loop. Our results uncover an interconnected network of TG2/NF-κB and IL6/STAT3 signaling with autophagy regulation in MCL cells, the disruption of which may offer a promising therapeutic strategy. Cancer Res; 76(21); 6410-23. ©2016 AACR.

Reverse chemomodulatory effects of the SIRT1 activators resveratrol and SRT1720 in Ewing's sarcoma cells: resveratrol suppresses and SRT1720 enhances etoposide- and vincristine-induced anticancer activity

PURPOSE

SIRT1-activating compounds (STACs) may have potential in the management of cancer. However, the best-studied STAC, the naturally occurring compound resveratrol, is reported to have contradictory effects in combination chemotherapy regimens: It has been shown both to increase and to decrease the action of anticancer agents. To shed more light on this issue, we comparatively investigated the impact of resveratrol and the synthetic STAC SRT1720 on the responsiveness of Ewing's sarcoma (ES) cells to the chemotherapeutic drugs etoposide and vincristine.

METHODS

Because the effects of STACs can depend on the functionality of the tumor suppressor protein p53, we used three ES cell lines differing in their p53 status, i.e., wild-type p53 WE-68 cells, mutant p53 SK-ES-1 cells and p53 null SK-N-MC cells. Single agent and combination therapy effects were assessed by flow cytometric analyses of propidium iodide uptake and mitochondrial depolarization, by measuring caspase 3/7 activity and by gene expression profiling.

RESULTS

When applied as single agents, both STACs were effective in ES cells irrespective of their p53 status. Strikingly, however, when applied in conjunction with cytostatic agents, the STACs displayed reverse effects: SRT1720 largely enhanced etoposide- and vincristine-induced cell death, while resveratrol inhibited it. Combination index analyses validated the antipodal impact of the STACs on the effectiveness of the chemotherapeutics.

CONCLUSION

These findings suggest that the synthetic STAC SRT1720 may be useful to enhance the efficacy of anticancer therapy in ES. But they also suggest that the dietary intake of the natural STAC resveratrol may be detrimental during chemotherapy of ES.

Occludin controls HIV transcription in brain pericytes via regulation of SIRT-1 activation

HIV invades the brain early after infection; however, its interactions with the cells of the blood-brain barrier (BBB) remain poorly understood. Our goal was to evaluate the role of occludin, one of the tight junction proteins that regulate BBB functions in HIV infection of BBB pericytes. We provide evidence that occludin levels largely control the metabolic responses of human pericytes to HIV. Occludin in BBB pericytes decreased by 10% during the first 48 h after HIV infection, correlating with increased nuclear translocation of the gene repressor C-terminal-binding protein (CtBP)-1 and NFκB-p65 activation. These changes were associated with decreased expression and activation of the class III histone deacetylase sirtuin (SIRT)-1. Occludin levels recovered 96 h after infection, restoring SIRT-1 and reducing HIV transcription to 20% of its highest values. We characterized occludin biochemically as a novel NADH oxidase that controls the expression and activation of SIRT-1. The inverse correlation between occludin and HIV transcription was then replicated in human primary macrophages and differentiated monocytic U937 cells, in which occludin silencing resulted in 75 and 250% increased viral transcription, respectively. Our work shows that occludin has previously unsuspected metabolic properties and is a target of HIV infection, opening the possibility of designing novel pharmacological approaches to control HIV transcription.

Drugs acting on homeostasis: challenging cancer cell adaptation

Cancer treatment aims to exploit properties that define malignant cells. In recent years, it has become apparent that malignant cells often survive cancer treatment and ensuing cell stress by switching on auxiliary turnover pathways, changing cellular metabolism and, concomitantly, the gene expression profile. The changed profile impacts the material exchange of cancer cells with affected tissues. Herein, we show that pathways of proteostasis and energy generation regulate common transcription factors. Namely, when one pathway of intracellular turnover is blocked, it triggers alternative turnover mechanisms, which induce transcription factor proteins that control expression of cytokines and regulators of apoptosis, cell division, differentiation, metabolism, and response to hormones. We focus on several alternative turnover mechanisms that can be blocked by drugs already used in clinical practice for the treatment of other non-cancer related diseases. We also discuss paradigms on the challenges posed by cancer cell adaptation mechanisms.

Expression of SIRT1 and apoptosis-related proteins is predictive for lymph node metastasis and disease-free survival in luminal A breast cancer

Luminal A breast cancer can present with early, unexpected lymph node metastasis, and sentinel lymph node biopsy has been reported false negative in some cases. We aimed to construct a biomarker-based model that predicts lymph node metastasis in luminal A breast cancer, using expression of silent mating type information regulation 2 homolog 1 (SIRT1) and apoptosis-related factors, which are known to be closely related. We selected tissue samples of 278 cases of luminal A invasive ductal carcinoma, constructed tissue microarrays, and performed immunohistochemical staining for SIRT1 and four apoptosis-related proteins. In constructing the best predictive model for lymph node metastasis, six clinicopathological parameters and five molecular markers were considered. Independent factors predictive of lymph node metastasis were pT stage (OR 1.829, p = 0.027), lymphovascular invasion (OR 4.128, p < 0.001), and decreased expression of caspase-3 (OR 0.535, p = 0.034) and of SIRT1 (OR 0.526, p = 0.053). A combination nuclear grade, lymphovascular invasion, increased B-cell lymphoma 2 (Bcl-2) expression, and reduced expression of caspase-3 and of SIRT1 yielded the strongest predictive performance for lymph node metastasis with an area under the curve (AUC) of 0.696. This combination was also predictive of shortened disease-free survival (73.1 vs. 67.7 months, p = 0.003). Our data support a role of SIRT1 protein as tumor suppressor in luminal A breast cancer, in association with apoptosis-related proteins. Our model based upon a combination of these biomarkers is expected to increase accuracy of prediction of lymph node metastasis in luminal A breast cancer. This might serve as a valuable tool in determining the optimal surgical strategy in breast cancer patients.

Molecular Mechanism of the Cell Death Induced by the Histone Deacetylase Pan Inhibitor LBH589 (Panobinostat) in Wilms Tumor Cells

Background

Wilms tumor (WT) is an embryonic kidney cancer, for which histone acetylation might be a therapeutic target. LBH589, a novel targeted agent, suppresses histone deacetylases in many tumors. This study investigated the antitumor activity of LBH589 in SK-NEP-1 and G401 cells.

Methods

SK-NEP-1 and G401 cell growth was assessed by CCK-8 and in nude mice experiments. Annexin V/propidium iodide staining followed by flow cytometry detected apoptosis in cell culture. Gene expressions of LBH589-treated tumor cells were analyzed using an Arraystar Human LncRNA Array. The Multi Experiment View cluster software analyzed the expression data. Differentially expressed genes from the cluster analyses were imported into the Ingenuity Pathway Analysis tool.

Results

LBH589 inhibited cell proliferation of SK-NEP-1 and G401 cells in a dose-dependent manner. Annexin V, TUNEL and Hochest 33342 staining analysis showed that LBH589-treated cells showed more apoptotic features compared with the control. LBH589 treatment inhibited the growth of SK-NEP-1 xenograft tumors in nude mice. Arraystar Human LncRNA Array analysis of genes and lncRNAs regulated by LBH589 identified 6653 mRNAs and 8135 lncRNAs in LBH589-treated SK-NEP-1 cells. The most enriched gene ontology terms were those involved in nucleosome assembly. KEGG pathway analysis identified cell cycle proteins, including CCNA2, CCNB2, CCND1, CCND2, CDK4, CDKN1B and HDAC2, etc. Ingenuity Pathway Analysis identified important upstream molecules: HIST2H3C, HIST1H4A, HIST1A, HIST1C, HIST1D, histone H1, histone H3, RPRM, HSP70 and MYC.

Conclusions

LBH589 treatment caused apoptosis and inhibition of cell proliferation of SK-NEP-1and G401 cells. LBH589 had a significant effect and few side effects on SK-NEP-1 xenograft tumors. Expression profiling, and GO, KEGG and IPA analyses identified new targets and a new “network” of genes responding to LBH589 treatment in SK-NEP-1 cells. RPRM, HSP70 and MYC may be important regulators during LBH589 treatment. Our results provide new clues to the proapoptotic mechanism of LBH589.

P300-dependent STAT3 acetylation is necessary for angiotensin II-induced pro-fibrotic responses in renal tubular epithelial cells

AIM

To explore the signal transducer and activator of transcription 3 (STAT3) signaling pathway, especially STAT3 acetylation, in angiotensin II (Ang II)-induced pro-fibrotic responses in renal tubular epithelial cells.

METHODS

Rat renal tubular epithelial cell line (NRK-52E) was used. STAT3 acetylation and phosphorylation, as well as the expression of fibronectin, collagen IV and transforming growth factor-β1 (TGF-β1) were examined using Western blotting. The level and localization of STAT3 phosphorylation on Tyr705 were detected with fluorescence immunocytochemistry. The cells were transfected with a plasmid vector carrying p300 gene or siRNA targeting p300 to regulate p300 expression.

RESULTS

Overexpression of p300 significantly increased STAT3 acetylation on Lys685, STAT3 phosphorylation on Tyr705, and the expression of TGF-β1, collagen IV and fibronectin in the cells. Treatment of the cells with Ang II (1 μmol/L) significantly increased STAT3 phosphorylation on Tyr705 through JAK2 activation, and dose-dependently increased the expression of fibronectin, collagen IV and TGF-β1. Pretreatment with curcumin, an inhibitor of JAK2 and p300, blocked Ang II-induced effects. Knockdown of p300 significantly decreased STAT3 acetylation on Lys685, and abolished Ang II-stimulated STAT3 phosphorylation on Tyr705, whereas pretreatment of the cells with C646, a selective inhibitor of p300, inhibited Ang II-induced STAT3 nuclear translocation and the expression of TGF-β1, collagen IV and fibronectin. Pretreatment of the cells with AG490, a JAK2 inhibitor, markedly inhibited Ang II-induced STAT3 phosphorylation on Tyr705 and fibronectin expression.

CONCLUSION

p300-dependent STAT3 acetylation is necessary for Ang II-induced STAT3 phosphorylation and the consequent pro-fibrotic responses in renal tubular epithelial cells in vitro.

Inhibition of STAT3 acetylation is associated with angiotesin renal fibrosis in the obstructed kidney

AIM

To explore the relationship between the signal transducer and activator of transcription 3 (STAT3) signaling and renal fibrosis.

METHODS

Rat renal tubular epithelial NRK-52E cells were treated with angiotesin II (Ang II), nicotinamide (an inhibitor of NAD+-dependent class III protein deacetylases, SIRT1-7), or resveratrol (an activator of SIRT1). Mice underwent unilateral ureteral obstruction (UUO) were used for in vivo studies. Renal interstitial fibrosis was observed with HE and Masson's trichrome staining. STAT3 acetylation and phosphorylation, fibronectin, collagen I, collagen IV, and α-smooth muscle actin (α-SMA) levels were examined using Western blotting.

RESULTS

Nicotinamide (0.625-10 mmol/L) dose-dependently increased STAT3 acetylation on Lys685 and phosphorylation on Tyr705 in NRK-52E cells, accompanied by accumulation of fibronectin and collagen IV. Ang II increased STAT3 phosphorylation on Tyr705 and the expression of fibronectin, collagen IV and α-SMA in the cells. Pretreatment with resveratrol (12.5 μmol/L) blocked Ang II-induced effects in the cells. UUO induced marked STAT3 phosphorylation, fibronectin, collagen IV and α-SMA accumulation, and renal interstitial fibrosis in the obstructed kidneys, which were significantly attenuated by daily administration of resveratrol (100 mg/kg).

CONCLUSION

STAT3 acetylation plays an important role in activation of STAT3 signaling pathway and consequent renal fibrosis.

GADD45 proteins: roles in cellular senescence and tumor development

The growth arrest and DNA damage 45 (GADD45) family genes regulate DNA repair, cell cycle, cell survival, apoptosis, senescence, and DNA demethylation in the cells under various stress stimuli, such as oxidative stress, UV radiation, and oncogenic stress. Recent studies have provided important insights regarding how different oncogenic stresses activate GADD45 signaling pathway and lead to disparate influences on tumor initiation. In this review, we discuss the deregulation and cellular function of GADD45 proteins in the context of cancer development. We also highlight recent advances in exploring the tumor suppressive function of GADD45 proteins-triggered cellular senescence.

Chemical composition of total flavonoids from Salvia chinensia Benth and their pro-apoptotic effect on hepatocellular carcinoma cells: potential roles of suppressing cellular NF-κB signaling

Salvia chinensia Benth (S. chinensia) is a medical plant that has been traditionally applied for centuries in the treatment of malignant diseases including hepatocellular carcinoma (HCC). However, the scientific basis underlying its anti-HCC activity has not been fully established. In this study, the chemical profiles of total flavonoids from S. chinensia (TFSC) were explored. Thirteen compounds which constituted the major components of TFSC were separated and identified. Flow cytometry analysis and caspase activity assays showed that TFSC dose-dependently induced HepG2 and Huh-7 HCC cell apoptosis. TFSC was also shown to substantially suppress NF-κB activity in HCC cells. Moreover, TFSC significantly repressed transplanted murine H22 ascitic hepatic cancer cell growth in vivo. Further studies revealed that TFSC induced HCC cell apoptosis and inhibited expressional levels of NF-κB responsive genes in transplanted tumor tissues. In addition, the toxic impact of TFSC on tumor-bearing mice was undetectable. These results indicate that TFSC induces HCC cell apoptosis both in vitro and in vivo. The suppression of cellular NF-κB activity is implicated in the TFSC-mediated HCC cell apoptosis.