Akt-dependent activation of mTORC1 complex involves phosphorylation of mTOR (mammalian target of rapamycin) by IκB kinase α (IKKα)

Catharanthine, an anticancer vinca alkaloid: an in silico and in vitro analysis of the autophagic system as the major mechanism of cell death in liver HepG2 cells

Catharanthine, a component of the anticancer drug vinblastine along with vindoline, disrupts the cell cycle by interfering with mitotic spindle formation. Apart from their antioxidant properties, vinca alkaloids like catharanthine inhibit phosphodiesterase activity and elevate intracellular cAMP levels. The aim of this study was to investigate how catharantine affects apoptosis and autophagy. This study conducted experiments on HepG2 liver carcinoma cells with varying doses of catharanthine to evaluate cell death rates and viability and determine the IC50 concentration via MTT assays. The apoptotic and autophagic effects of catharanthine were assessed using flow cytometry with annexin V and PI staining, while the expression of autophagy-related genes was analyzed through quantitative PCR. Additionally, molecular docking and molecular dynamics simulations were employed to further investigate catharanthine's impact on autophagy mechanisms. The study showed that catharanthine reduced oxidative stress and triggered apoptosis in HepG2 cells in a dose-dependent manner. Catharanthine also upregulated the expression of autophagy-related genes like LC3, Beclin1, and ULK1. Notably, catharanthine increased sirtuin-1 levels, a known autophagy inducer, while decreasing Akt expression compared to untreated cells. Molecular docking results indicated rapamycin had a stronger binding affinity with FRB (-10.7 KJ/mol-1) than catharanthine (-7.3 KJ/mol-1). Additionally, molecular dynamics simulations revealed that catharanthine interacted effectively with the FRB domain of mTOR, displaying stability and a strong binding affinity, although not as potent as rapamycin. In summary, besides its cytotoxic and pro-apoptotic effects, catharanthine activates autophagy signaling pathways and induces autophagic necrosis by inhibiting mTOR.

Unlocking new avenues for neuropsychiatric disease therapy: the emerging potential of Peroxisome proliferator-activated receptors as promising therapeutic targets

RATIONALE

Peroxisome proliferator-activated receptors (PPARs) are transcription factors that regulate various physiological processes such as inflammation, lipid metabolism, and glucose homeostasis. Recent studies suggest that targeting PPARs could be beneficial in treating neuropsychiatric disorders by modulating neuronal function and signaling pathways in the brain. PPAR-α, PPAR-δ, and PPAR-γ have been found to play important roles in cognitive function, neuroinflammation, and neuroprotection. Dysregulation of PPARs has been associated with neuropsychiatric disorders like bipolar disorder, schizophrenia, major depression disorder, and autism spectrum disorder. The limitations and side effects of current treatments have prompted research to target PPARs as a promising novel therapeutic strategy. Preclinical and clinical studies have shown the potential of PPAR agonists and antagonists to improve symptoms associated with these disorders.

OBJECTIVE

This review aims to provide an overview of the current understanding of PPARs in neuropsychiatric disorders, their potential as therapeutic targets, and the challenges and future directions for developing PPAR-based therapies.

METHODS

An extensive literature review of various search engines like PubMed, Medline, Bentham, Scopus, and EMBASE (Elsevier) databases was carried out with the keywords "PPAR, Neuropsychiatric disorders, Oxidative stress, Inflammation, Bipolar Disorder, Schizophrenia, Major depression disorder, Autism spectrum disorder, molecular pathway".

RESULT & CONCLUSION

Although PPARs present a hopeful direction for innovative therapeutic approaches in neuropsychiatric conditions, additional research is required to address obstacles and convert this potential into clinically viable and individualized treatments.

The multiple roles of autophagy in uveal melanoma and the microenvironment

PURPOSE

Uveal melanoma (UM) is the most common primary malignant intraocular tumor in adults, and effective clinical treatment strategies are still lacking. Autophagy is a lysosome-dependent degradation system that can encapsulate abnormal proteins, damaged organelles. However, dysfunctional autophagy has multiple types and plays a complex role in tumorigenicity depending on many factors, such as tumor stage, microenvironment, signaling pathway activation, and application of autophagic drugs.

METHODS

A systematic review of the literature was conducted to analyze the role of autophagy in UM, as well as describing the development of autophagic drugs and the link between autophagy and the tumor microenvironment.

RESULTS

In this review, we summarize current research advances regarding the types of autophagy, the mechanisms of autophagy, the application of autophagy inhibitors or agonists, autophagy and the tumor microenvironment. Finally, we also discuss the relationship between autophagy and UM.

CONCLUSION

Understanding the molecular mechanisms of how autophagy differentially affects tumor progression may help to design better therapeutic regimens to prevent and treat UM.

Human cytomegalovirus modulates mTORC1 to redirect mRNA translation within quiescently infected monocytes

Human cytomegalovirus (HCMV) utilizes peripheral blood monocytes as a means to systemically disseminate throughout the host. Following viral entry, HCMV stimulates non-canonical Akt signaling leading to the activation of mTORC1 and the subsequent translation of select antiapoptotic proteins within infected monocytes. However, the full extent to which the HCMV-initiated Akt/mTORC1 signaling axis reshapes the monocyte translatome is unclear. We found HCMV entry alone was able to stimulate widescale changes to mRNA translation levels and that inhibition of mTOR, a component of mTORC1, dramatically attenuated HCMV-induced protein synthesis. Although monocytes treated with normal myeloid growth factors also exhibited increased levels of translation, mTOR inhibition had no effect, suggesting HCMV activation of mTOR stimulates the acquisition of a unique translatome within infected monocytes. Indeed, polyribosomal profiling of HCMV-infected monocytes identified distinct prosurvival transcripts that were preferentially loaded with ribosomes when compared to growth factor-treated cells. Sirtuin 1 (SIRT1), a deacetylase that exerts prosurvival effects through regulation of the PI3K/Akt pathway, was found to be highly enriched following HCMV infection in an mTOR-dependent manner. Importantly, SIRT1 inhibition led to the death of HCMV-infected monocytes while having minimal effect on uninfected cells. SIRT1 also supported a positive feedback loop to sustain Akt/mTORC1 signaling following viral entry. Taken together, HCMV profoundly reshapes mRNA translation in an mTOR-dependent manner to enhance the synthesis of select factors necessary for the survival of infected monocytes.IMPORTANCEHuman cytomegalovirus (HCMV) infection is a significant cause of morbidity and mortality among the immunonaïve and immunocompromised. Peripheral blood monocytes are a major cell type responsible for disseminating the virus from the initial site of infection. In order for monocytes to mediate viral spread within the host, HCMV must subvert the naturally short lifespan of these cells. In this study, we performed polysomal profiling analysis, which demonstrated HCMV to globally redirect mRNA translation toward the synthesis of cellular prosurvival factors within infected monocytes. Specifically, HCMV entry into monocytes induced the translation of cellular SIRT1 to generate an antiapoptotic state. Defining the precise mechanisms through which HCMV stimulates survival will provide insight into novel anti-HCMV drugs able to target infected monocytes.

Cryptolepine Analog Exhibits Antitumor Activity against Ehrlich Ascites Carcinoma Cells in Mice via Targeting Cell Growth, Oxidative Stress, and PTEN/Akt/mTOR Signaling Pathway

BACKGROUND

The efficacy of chemotherapy continues to be limited due to associated toxicity and chemoresistance. Thus, synthesizing and investigating novel agents for cancer treatment that could potentially eliminate such limitations is imperative.

OBJECTIVE

The current study aims to explore the anticancer potency of cryptolepine (CPE) analog on Ehrlich ascites carcinoma cells (EACs) in mice.

METHODS

The effect of a CPE analog on EAC cell viability and ascites volume, as well as malonaldehyde, total antioxidant capacity, and catalase, were estimated. The concentration of caspase-8 and mTOR in EACs was also measured, and the expression levels of PTEN and Akt were determined.

RESULTS

Results revealed that CPE analog exerts a cytotoxic effect on EAC cell viability and reduces the ascites volume. Moreover, this analog induces oxidative stress in EACs by increasing the level of malonaldehyde and decreasing the level of total antioxidant capacity and catalase activity. It also induces apoptosis by elevating the concentration of caspase-8 in EACs. Furthermore, it decreases the concentration of mTOR in EACs. Moreover, it upregulates the expression of PTEN and downregulates the expression of Akt in EACs.

CONCLUSION

Our findings showed the anticancer activity of CPE analog against EACs in mice mediated by regulation of the PTEN/Akt/mTOR signaling pathway.

mTOR signalling pathway in stem cell bioactivities and angiogenesis potential

The mammalian target of rapamycin (mTOR) is a protein kinase that responds to different stimuli such as stresses, starvation and hypoxic conditions. The modulation of this effector can lead to the alteration of cell dynamic growth, proliferation, basal metabolism and other bioactivities. Considering this fact, the mTOR pathway is believed to regulate the diverse functions in several cell lineages. Due to the pleiotropic effects of the mTOR, we here, hypothesize that this effector can also regulate the bioactivity of stem cells in response to external stimuli pathways under physiological and pathological conditions. As a correlation, we aimed to highlight the close relationship between the mTOR signalling axis and the regenerative potential of stem cells in a different milieu. The relevant publications were included in this study using electronic searches of the PubMed database from inception to February 2023. We noted that the mTOR signalling cascade can affect different stem cell bioactivities, especially angiogenesis under physiological and pathological conditions. Modulation of mTOR signalling pathways is thought of as an effective strategy to modulate the angiogenic properties of stem cells.

Sleep disturbance induces a modulation of clock gene expression and alters metabolism regulation in drosophila

Sleep disorders are catching attention worldwide as they can induce dyshomeostasis and health issues in all animals, including humans. Circadian rhythms are biological 24-hour cycles that influence physiology and behavior in all living organisms. Sleep is a crucial resting state for survival and is under the control of circadian rhythms. Studies have shown the influence of sleep on various pathological conditions, including metabolic diseases; however, the biological mechanisms involving the circadian clock, sleep, and metabolism regulation are not well understood. In previous work, we standardized a sleep disturbance protocol and, observed that short-time sleep deprivation and sleep-pattern alteration induce homeostatic sleep regulation, locomotor deficits, and increase oxidative stress. Now, we investigated the relationship between these alterations with the circadian clock and energetic metabolism. In this study, we evaluated the expression of the circadian clock and drosophila insulin-like peptides (DILPs) genes and metabolic markers glucose, triglycerides, and glycogen in fruit flies subjected to short-term sleep disruption protocols. The sleep disturbance altered the expression of clock genes and DILPs genes expression, and modulated glucose, triglycerides, and glycogen levels. Moreover, we demonstrated changes in mTor/dFoxo genes, AKT phosphorylation, and dopamine levels in nocturnal light-exposed flies. Thus, our results suggest a connection between clock genes and metabolism disruption as a consequence of sleep disruption, demonstrating the importance of sleep quality in health maintenance.

Chemical Profiling and Biological Activity of Psydrax dicoccos Gaertn

Breast cancer is one of the deadliest diseases in women with a mortality rate of 6.6%. Adverse effects of synthetic drugs have directed research toward safer alternatives such as natural compounds. This study focused on Psydrax dicoccos Gaertn, an evergreen tree abundantly distributed in Tamil Nadu (India) for its possible application against breast cancer cells. P. dicoccos leaf methanol extract, found within a wide range of phytochemicals, demonstrated cytotoxic effects against MCF7 breast cancer cells at IC50 of 34 μg/mL. The extract exhibited good antioxidant activities against DPPH• (62%) and ABTS•+ (80%), as well as concentration-dependent (100-800 μg/mL) anti-inflammatory potential of 18-60% compared to standards, ascorbic acid or aspirin, respectively. Moreover, even low extract concentrations (10 μg/mL) inhibited the growth of Escherichia coli (1.9 ± 0.6 mm) and Pseudomonas aeruginosa (2.3 ± 0.7 mm), thus showing high antimicrobial and anti-inflammatory potential. GC-MS and LC-MS analyses identified 31 and 16 components, respectively, of which selected compounds were used to evaluate the interaction between key receptors (AKT-1, COX-2, and HER-2) of breast cancer based on binding energy (ΔG) and inhibition constant (Ki). The results indicate that bioactive compounds from P. dicoccos have potential against breast cancer cells, but further evaluations are needed.

APPlications of amyloid-β precursor protein metabolites in macrocephaly and autism spectrum disorder

Metabolites of the Amyloid-β precursor protein (APP) proteolysis may underlie brain overgrowth in Autism Spectrum Disorder (ASD). We have found elevated APP metabolites (total APP, secreted (s) APPα, and α-secretase adamalysins in the plasma and brain tissue of children with ASD). In this review, we highlight several lines of evidence supporting APP metabolites' potential contribution to macrocephaly in ASD. First, APP appears early in corticogenesis, placing APP in a prime position to accelerate growth in neurons and glia. APP metabolites are upregulated in neuroinflammation, another potential contributor to excessive brain growth in ASD. APP metabolites appear to directly affect translational signaling pathways, which have been linked to single gene forms of syndromic ASD (Fragile X Syndrome, PTEN, Tuberous Sclerosis Complex). Finally, APP metabolites, and microRNA, which regulates APP expression, may contribute to ASD brain overgrowth, particularly increased white matter, through ERK receptor activation on the PI3K/Akt/mTOR/Rho GTPase pathway, favoring myelination.

Reactive Oxygen Species and H. pylori Infection: A Comprehensive Review of Their Roles in Gastric Cancer Development

Gastric cancer (GC) is the fifth most common cancer worldwide and makes up a significant component of the global cancer burden. Helicobacter pylori (H. pylori) is the most influential risk factor for GC, with the International Agency for Research on Cancer classifying it as a Class I carcinogen for GC. H. pylori has been shown to persist in stomach acid for decades, causing damage to the stomach's mucosal lining, altering gastric hormone release patterns, and potentially altering gastric function. Epidemiological studies have shown that eliminating H. pylori reduces metachronous cancer. Evidence shows that various molecular alterations are present in gastric cancer and precancerous lesions associated with an H. pylori infection. However, although H. pylori can cause oxidative stress-induced gastric cancer, with antioxidants potentially being a treatment for GC, the exact mechanism underlying GC etiology is not fully understood. This review provides an overview of recent research exploring the pathophysiology of H. pylori-induced oxidative stress that can cause cancer and the antioxidant supplements that can reduce or even eliminate GC occurrence.

A new osteogenic protein isolated from Dioscorea opposita Thunb accelerates bone defect healing through the mTOR signaling axis

Delayed bone defect repairs lead to severe health and socioeconomic impacts on patients. Hence, there are increasing demands for medical interventions to promote bone defect healing. Recombinant proteins such as BMP-2 have been recognized as one of the powerful osteogenic substances that promote mesenchymal stem cells (MSCs) to osteoblast differentiation and are widely applied clinically for bone defect repairs. However, recent reports show that BMP-2 treatment has been associated with clinical adverse side effects such as ectopic bone formation, osteolysis and stimulation of inflammation. Here, we have identified one new osteogenic protein, named 'HKUOT-S2' protein, from Dioscorea opposita Thunb. Using the bone defect model, we have shown that the HKUOT-S2 protein can accelerate bone defect repair by activating the mTOR signaling axis of MSCs-derived osteoblasts and increasing osteoblastic biomineralization. The HKUOT-S2 protein can also modulate the transcriptomic changes of macrophages, stem cells, and osteoblasts, thereby enhancing the crosstalk between the polarized macrophages and MSCs-osteoblast differentiation to facilitate osteogenesis. Furthermore, this protein had no toxic effects in vivo. We have also identified HKUOT-S2 peptide sequence TKSSLPGQTK as a functional osteogenic unit that can promote osteoblast differentiation in vitro. The HKUOT-S2 protein with robust osteogenic activity could be a potential alternative osteoanabolic agent for promoting osteogenesis and bone defect repairs. We believe that the HKUOT-S2 protein may potentially be applied clinically as a new class of osteogenic agent for bone defect healing.

TET2 is required to suppress mTORC1 signaling through urea cycle with therapeutic potential

Tumor development, involving both cell growth (mass accumulation) and cell proliferation, is a complex process governed by the interplay of multiple signaling pathways. TET2 mainly functions as a DNA dioxygenase, which modulates gene expression and biological functions via oxidation of 5mC in DNA, yet whether it plays a role in regulating cell growth remains unknown. Here we show that TET2 suppresses mTORC1 signaling, a major growth controller, to inhibit cell growth and promote autophagy. Mechanistically, TET2 functions as a 5mC "eraser" by mRNA oxidation, abolishes YBX1-HuR binding and promotes decay of urea cycle enzyme mRNAs, thus negatively regulating urea cycle and arginine production, which suppresses mTORC1 signaling. Therefore, TET2-deficient tumor cells are more sensitive to mTORC1 inhibition. Our results uncover a novel function for TET2 in suppressing mTORC1 signaling and inhibiting cell growth, linking TET2-mediated mRNA oxidation to cell metabolism and cell growth control. These findings demonstrate the potential of mTORC1 inhibition as a possible treatment for TET2-deficient tumors.

T cells in health and disease

T cells are crucial for immune functions to maintain health and prevent disease. T cell development occurs in a stepwise process in the thymus and mainly generates CD4⁺ and CD8⁺ T cell subsets. Upon antigen stimulation, naïve T cells differentiate into CD4⁺ helper and CD8⁺ cytotoxic effector and memory cells, mediating direct killing, diverse immune regulatory function, and long-term protection. In response to acute and chronic infections and tumors, T cells adopt distinct differentiation trajectories and develop into a range of heterogeneous populations with various phenotype, differentiation potential, and functionality under precise and elaborate regulations of transcriptional and epigenetic programs. Abnormal T-cell immunity can initiate and promote the pathogenesis of autoimmune diseases. In this review, we summarize the current understanding of T cell development, CD4⁺ and CD8⁺ T cell classification, and differentiation in physiological settings. We further elaborate the heterogeneity, differentiation, functionality, and regulation network of CD4⁺ and CD8⁺ T cells in infectious disease, chronic infection and tumor, and autoimmune disease, highlighting the exhausted CD8⁺ T cell differentiation trajectory, CD4⁺ T cell helper function, T cell contributions to immunotherapy and autoimmune pathogenesis. We also discuss the development and function of γδ T cells in tissue surveillance, infection, and tumor immunity. Finally, we summarized current T-cell-based immunotherapies in both cancer and autoimmune diseases, with an emphasis on their clinical applications. A better understanding of T cell immunity provides insight into developing novel prophylactic and therapeutic strategies in human diseases.

Molecular treatment trajectories within psoriatic T lymphocytes: a mini review

Multiple biological processes in mammalian cells are implicated in psoriasis (Ps) development and progression, as well as in the pathogenic mechanisms associated with this chronic immune-mediated inflammatory disease (IMID). These refer to molecular cascades contributing to the pathological topical and systemic reactions in Ps, where local skin-resident cells derived from peripheral blood and skin-infiltrating cells originating from the circulatory system, in particular T lymphocytes (T cells), are key actors. The interplay between molecular components of T cell signalling transduction and their involvement in cellular cascades (i.e. throughout Ca²⁺/CaN/NFAT, MAPK/JNK, PI3K/Akt/mTOR, JAK/STAT pathways) has been of concern in the last few years; this is still less characterised than expected, even though some evidence has accumulated to date identifying them as potential objects in the management of Ps. Innovative therapeutic strategies for the use of compounds such as synthetic Small Molecule Drugs (SMDs) and their various combinations proved to be promising tools for the treatment of Ps via incomplete blocking, also known as modulation of disease-associated molecular tracks. Despite recent drug development having mainly centred on biological therapies for Ps, yet displaying serious limitations, SMDs acting on specific pathway factor isoforms or single effectors within T cell, could represent a valid innovation in real-world treatment patterns in patients with Ps. Of note, due to the intricate crosstalk between intracellular pathways, the use of selective agents targeting proper tracks is, in our opinion, a challenge for modern science regarding the prevention of disease at its onset and also in the prediction of patient response to Ps treatment.

eEF1A2 siRNA Suppresses MPP+-Induced Activation of Akt and mTOR and Potentiates Caspase-3 Activation in a Parkinson’s Disease Model

The tissue-specific protein eEF1A2 has been linked to the development of neurological disorders. The role of eEF1A2 in the pathogenesis of Parkinson’s disease (PD) has yet to be investigated. The aim of this study was to determine the potential neuroprotective effects of eEF1A2 in an MPP+ model of PD. Differentiated SH-SY5Y cells were transfected with eEF1A2 siRNA, followed by MPP+ exposure. The expression of p-Akt1 and p-mTORC1 was determined using Western blotting. The expression of p53, Bax, Bcl-2, and caspase-3 was evaluated using qRT-PCR. Cleaved caspase-3 levels and Annexin V/propidium iodide flow cytometry were used to determine apoptosis. The effects of PI3K inhibition were examined. The results showed that eEF1A2 siRNA significantly reduced the eEF1A2 expression induced by MPP+. MPP+ treatment activated Akt1 and mTORC1; however, eEF1A2 knockdown suppressed this activation. In eEF1A2-knockdown cells, MPP+ treatment increased the expression of p53 and caspase-3 mRNA levels as well as increased apoptotic cell death when compared to MPP+ treatment alone. In cells exposed to MPP+, upstream inhibition of the Akt/mTOR pathway, by either LY294002 or wortmannin, inhibited the phosphorylation of Akt1 and mTORC1. Both PI3K inhibitors increased eEF1A2 expression in cells, whether or not they were also treated with MPP+. In conclusion, eEF1A2 may function as a neuroprotective factor against MPP+, in part by regulating the Akt/mTOR pathway upstream.

N6 - Methyladenosine defines a new checkpoint in γδ T cell development

T cells, which are derived from hematopoietic stem cells (HSCs), are the most important components of adaptive immune system. Based on the expression of αβ and γδ receptors, T cells are mainly divided into αβ and γδ T cells. In the thymus, they share common progenitor cells, while undergoing a series of well-characterized and different developmental processes. N⁶ -Methyladenosine (m⁶ A), one of the most abundant modifications in mRNAs, plays critical roles in cell development and maintenance of function. Recently, we have demonstrated that the depletion of m⁶ A demethylase ALKBH5 in lymphocytes specifically induces an expansion of γδ T cells through the regulation of Jag1/Notch2 signaling, but not αβ T cells, indicating a checkpoint role of ALKBH5 and m⁶ A modification in the early development of γδ T cells. Based on previous studies, many key pathway molecules, which exert dominant roles in γδ T cell fate determination, have been identified as the targets regulated by m⁶ A modification. In this review, we mainly summarize the potential regulation between m⁶ A modification and these key signaling molecules in the γδ T cell lineage commitment, to provide new perspectives in the checkpoint of γδ T cell development.

Chrysophanol-Induced Autophagy Disrupts Apoptosis via the PI3K/Akt/mTOR Pathway in Oral Squamous Cell Carcinoma Cells

Background and Objectives: Natural products are necessary sources for drug discovery and have contributed to cancer chemotherapy over the past few decades. Furthermore, substances derived from plants have fewer side effects. Chrysophanol is an anthraquinone derivative that is isolated from rhubarb. Although the anticancer effect of chrysophanol on several cancer cells has been reported, studies on the antitumor effect of chrysophanol on oral squamous-cell carcinoma (OSCC) cells have yet to be elucidated. Therefore, in this study, we investigated the anticancer effect of chrysophanol on OSCC cells (CAL-27 and Ca9-22) via apoptosis and autophagy, among the cell death pathways. Results: It was found that chrysophanol inhibited the growth and viability of CAL-27 and Ca9-22 and induced apoptosis through the intrinsic pathway. It was also found that chrysophanol activates autophagy-related factors (ATG5, beclin-1, and P62/SQSTM1) and LC3B conversion. That is, chrysophanol activated both apoptosis and autophagy. Here, we focused on the roles of chrysophanol-induced apoptosis and the autophagy pathway. When the autophagy inhibitor 3-MA and PI3K/Akt inhibitor were used to inhibit the autophagy induced by chrysophanol, it was confirmed that the rate of apoptosis significantly increased. Therefore, we confirmed that chrysophanol induces apoptosis and autophagy at the same time, and the induced autophagy plays a role in interfering with apoptosis processes. Conclusions: Therefore, the potential of chrysophanol as an excellent anticancer agent in OSCC was confirmed via this study. Furthermore, the combined treatment of drugs that can inhibit chrysophanol-induced autophagy is expected to have a tremendous synergistic effect in overcoming oral cancer.

Age-Related Oxidative Redox and Metabolic Changes Precede Intraneuronal Amyloid-β Accumulation and Plaque Deposition in a Transgenic Alzheimer's Disease Mouse Model

BACKGROUND

Many identified mechanisms could be upstream of the prominent amyloid-β (Aβ) plaques in Alzheimer's disease (AD).

OBJECTIVE

To profile the progression of pathology in AD.

METHODS

We monitored metabolic signaling, redox stress, intraneuronal amyloid-β (iAβ) accumulation, and extracellular plaque deposition in the brains of 3xTg-AD mice across the lifespan.

RESULTS

Intracellular accumulation of aggregated Aβ in the CA1 pyramidal cells at 9 months preceded extracellular plaques that first presented in the CA1 at 16 months of age. In biochemical assays, brain glutathione (GSH) declined with age in both 3xTg-AD and non-transgenic controls, but the decline was accelerated in 3xTg-AD brains from 2 to 4 months. The decline in GSH correlated exponentially with the rise in iAβ. Integrated metabolic signaling as the ratio of phospho-Akt (pAkt) to total Akt (tAkt) in the PI3kinase and mTOR pathway declined at 6, 9, and 12 months, before rising at 16 and 20 months. These pAkt/tAkt ratios correlated with both iAβ and GSH levels in a U-shaped relationship. Selective vulnerability of age-related AD-genotype-specific pAkt changes was greatest in the CA1 pyramidal cell layer. To demonstrate redox causation, iAβ accumulation was lowered in cultured middle-age adult 3xTg-AD neurons by treatment of the oxidized redox state in the neurons with exogenous cysteine.

CONCLUSION

The order of pathologic progression in the 3xTg-AD mouse was loss of GSH (oxidative redox shift) followed by a pAkt/tAkt metabolic shift in CA1, iAβ accumulation in CA1, and extracellular Aβ deposition. Upstream targets may prove strategically more effective for therapy before irreversible changes.

Differential in vitro effects of targeted therapeutics in primary human liver cancer: importance for combined liver cancer

The incidence of primary liver tumors, hepatocellular carcinoma (HCC), intrahepatic cholangiocellular carcinoma (ICC), and combined HCC/ICC (cHCC/CC) is increasing. For ICC, targeted therapy exists only for a small subpopulation of patients, while for HCC, Sorafenib and Lenvatinib are in use. Diagnosis of cHCC/CC is a great challenge and its incidence is underestimated, bearing the risk of unintended non-treatment of ICC. Here, we investigated effects of targeted inhibitors on human ICC cell lines (HUH28, RBE, SSP25), in comparison to extrahepatic (E)CC lines (EGI1, CCC5, TFK1), and HCC/hepatoblastoma cell lines (HEP3B, HUH7, HEPG2). Cells were challenged with: AKT inhibitor MK-2206; multikinase inhibitors Sorafenib, Lenvatinib and Dasatinib; PI3-kinase inhibitors BKM-120, Wortmannin, LY294002, and CAL-101; and mTOR inhibitor Rapamycin. Dosage of the substances was based on the large number of published data of recent years. Proliferation was analyzed daily for four days. All cell lines were highly responsive to MK-2206. Thereby, MK-2206 reduced expression of phospho(p)-AKT in all ICC, ECC, and HCC lines, which mostly corresponded to reduction of p-mTOR, whereas p-ERK1/2 was upregulated in many cases. Lenvatinib showed inhibitory effects on the two HCC cell lines, but not on HEPG2, ICCs and ECCs. Sorafenib inhibited proliferation of all cells, except the ECC line CCC5. However, at reduced dosage, we observed increased cell numbers in some ICC experiments. Dasatinib was highly effective especially in ICC cell lines. Inhibitory effects were observed with all four PI3-kinase inhibitors. However, cell type-specific differences were also evident here. Rapamycin was most effective in the two HCC cell lines. Our studies show that the nine inhibitors differentially target ICC, ECC, and HCC/hepatoblastoma lines. Caution should be taken with Lenvatinib and Sorafenib administration in patients with cHCC/CC as the drugs may have no effects on, or might even stimulate, ICC.

S1P/S1PR1 signaling differentially regulates the allogeneic response of CD4 and CD8 T cells by modulating mitochondrial fission

Graft-versus-host disease (GVHD) significantly contributes to patient morbidity and mortality after allogeneic hematopoietic cell transplantation (allo-HSCT). Sphingosine-1-phosphate (S1P) signaling is involved in the biogenetic processes of different immune cells. In the current study, we demonstrated that recipient sphingosine kinase 1 (Sphk1), but not Sphk2, was required for optimal S1PR1-dependent donor T-cell allogeneic responses by secreting S1P. Using genetic and pharmacologic approaches, we demonstrated that inhibition of Sphk1 or S1PR1 substantially attenuated acute GVHD (aGVHD) while retaining the graft-versus-leukemia (GVL) effect. At the cellular level, the Sphk1/S1P/S1PR1 pathway differentially modulated the alloreactivity of CD4+ and CD8+ T cells; it facilitated T-cell differentiation into Th1/Th17 cells but not Tregs and promoted CD4+ T-cell infiltration into GVHD target organs but was dispensable for the CTL activity of allogeneic CD8+ T cells. At the molecular level, the Sphk1/S1P/S1PR1 pathway augmented mitochondrial fission and increased mitochondrial mass in allogeneic CD4+ but not CD8+ T cells by activating the AMPK/AKT/mTOR/Drp1 pathway, providing a mechanistic basis for GVL maintenance when S1P signaling was inhibited. For translational purposes, we detected the regulatory efficacy of pharmacologic inhibitors of Sphk1 and S1PR1 in GVHD induced by human T cells in a xenograft model. Our study provides novel mechanistic insight into how the Sphk1/S1P/S1PR1 pathway modulates T-cell alloreactivity and validates Sphk1 or S1PR1 as a therapeutic target for the prevention of GVHD and leukemia relapse. This novel strategy may be readily translated into the clinic to benefit patients with hematologic malignancies and disorders.

S1P/S1PR1 signaling differentially regulates the allogeneic response of CD4 and CD8 T cells by modulating mitochondrial fission

Graft-versus-host disease (GVHD) significantly contributes to patient morbidity and mortality after allogeneic hematopoietic cell transplantation (allo-HSCT). Sphingosine-1-phosphate (S1P) signaling is involved in the biogenetic processes of different immune cells. In the current study, we demonstrated that recipient sphingosine kinase 1 (Sphk1), but not Sphk2, was required for optimal S1PR1-dependent donor T-cell allogeneic responses by secreting S1P. Using genetic and pharmacologic approaches, we demonstrated that inhibition of Sphk1 or S1PR1 substantially attenuated acute GVHD (aGVHD) while retaining the graft-versus-leukemia (GVL) effect. At the cellular level, the Sphk1/S1P/S1PR1 pathway differentially modulated the alloreactivity of CD4⁺ and CD8⁺ T cells; it facilitated T-cell differentiation into Th1/Th17 cells but not Tregs and promoted CD4⁺ T-cell infiltration into GVHD target organs but was dispensable for the CTL activity of allogeneic CD8⁺ T cells. At the molecular level, the Sphk1/S1P/S1PR1 pathway augmented mitochondrial fission and increased mitochondrial mass in allogeneic CD4⁺ but not CD8⁺ T cells by activating the AMPK/AKT/mTOR/Drp1 pathway, providing a mechanistic basis for GVL maintenance when S1P signaling was inhibited. For translational purposes, we detected the regulatory efficacy of pharmacologic inhibitors of Sphk1 and S1PR1 in GVHD induced by human T cells in a xenograft model. Our study provides novel mechanistic insight into how the Sphk1/S1P/S1PR1 pathway modulates T-cell alloreactivity and validates Sphk1 or S1PR1 as a therapeutic target for the prevention of GVHD and leukemia relapse. This novel strategy may be readily translated into the clinic to benefit patients with hematologic malignancies and disorders.

Inhibition of IκB Kinase Is a Potential Therapeutic Strategy to Circumvent Resistance to Epidermal Growth Factor Receptor Inhibition in Triple-Negative Breast Cancer Cells

Triple-negative breast cancer (TNBC) remains as an intractable malignancy with limited therapeutic targets. High expression of epidermal growth factor receptor (EGFR) has been associated with a poor prognosis of TNBC; however, EGFR targeting has failed with unfavorable clinical outcomes. Here, we performed a combinatorial screening of fifty-five protein kinase inhibitors with the EGFR inhibitor gefitinib in the TNBC cell line MDA-MB-231 and identified the IκB kinase (IKK) inhibitor IKK16 as a sensitizer of gefitinib. Cell viability and clonogenic survival assays were performed to evaluate the antiproliferative effects of the gefitinib and IKK16 (Gefitinib + IKK16) combination in TNBC cell lines. Western blot analyses were also performed to reveal the potential mode of action of this combination. In addition, next-generation sequencing (NGS) analysis was performed in Gefitinib+IKK16-treated cells. The Gefitinib+IKK16 treatment synergistically reduced cell viability and colony formation of TNBC cell lines such as HS578T, MDA-MB-231, and MDA-MB-468. This combination downregulated p-STAT3, p-AKT, p-mTOR, p-GSK3β, and p-RPS6. In addition, p-NF-κB and the total NF-κB were also regulated by this combination. Furthermore, NGS analysis revealed that NF-κB/RELA targets including CCL2, CXCL8, EDN1, IL-1β, IL-6, and SERPINE1 were further reduced and several potential tumor suppressors, such as FABP3, FADS2, FDFT1, SEMA6A, and PCK2, were synergistically induced by the Gefitinib-+IKK16 treatment. Taken together, we identified the IKK/NF-κB pathway as a potential target in combination of EGFR inhibition for treating TNBC.

The importance of natural chalcones in ischemic organ damage: Comprehensive and bioinformatic analysis review

Over the last few decades, extensive research has been conducted, yielding a detailed account of thousands of newly discovered compounds of natural origin and their biological activities, all of which have the potential to be used for a wide range of therapeutic purposes. There are multiple research papers denoting the central objective of chalcones, which have been shown to have therapeutic potential against various forms of ischemia. The various aspects of chalcones are discussed in this review regarding molecular mechanisms involved in the promising anti-ischemic potential of these chalcones. The main mechanisms involved in these protective effects are Nrf2/Akt activation and NF-κB/TLR4 suppression. Furthermore, in-silico studies were carried out to discover the probable binding of these chalcones to Keap-1 (an inhibitor of Nrf2), Akt, NF-κB, and TLR4 protein molecules. Besides, network pharmacology analysis was conducted to predict the interacting partners of these signals. The obtained results indicated that Nrf2, Akt, NF-κB, and TLR4 are involved in the beneficial anti-ischemic actions of chalcones. Conclusively, the present findings show that chalcones as anti-ischemic agents have a valid rationale. The discussed studies will provide a comprehensive viewpoint on chalcones and can help to optimize their effects in different ischemia. PRACTICAL APPLICATIONS: Ischemic organ damage is an unavoidable pathological condition with a high worldwide incidence. According to the current research progress, natural chalcones have been proved to treat and/or prevent various types of ischemic organ damage by alleviating oxidative stress, inflammation, and apoptosis by different molecular mechanisms. This article displays the comprehensive research progress and the molecular basis of ischemic organ damage pathophysiology and introduces natural chalcones' mechanism in the ischemic organ condition.

Opioids and Vitamin C: Known Interactions and Potential for Redox-Signaling Crosstalk

Opioids are among the most widely used classes of pharmacologically active compounds both clinically and recreationally. Beyond their analgesic efficacy via μ opioid receptor (MOR) agonism, a prominent side effect is central respiratory depression, leading to systemic hypoxia and free radical generation. Vitamin C (ascorbic acid; AA) is an essential antioxidant vitamin and is involved in the recycling of redox cofactors associated with inflammation. While AA has been shown to reduce some of the negative side effects of opioids, the underlying mechanisms have not been explored. The present review seeks to provide a signaling framework under which MOR activation and AA may interact. AA can directly quench reactive oxygen and nitrogen species induced by opioids, yet this activity alone does not sufficiently describe observations. Downstream of MOR activation, confounding effects from AA with STAT3, HIF1α, and NF-κB have the potential to block production of antioxidant proteins such as nitric oxide synthase and superoxide dismutase. Further mechanistic research is necessary to understand the underlying signaling crosstalk of MOR activation and AA in the amelioration of the negative, potentially fatal side effects of opioids.

Chylomicron production is repressed by RPTOR knockdown, R-α-lipoic acid and 4-phenylbutyric acid in human enterocyte-like Caco-2 cells

Although the role of mechanistic target of rapamycin complex 1 (mTORC1) in lipid metabolism has been the subject of previous research, its function in chylomicron production is not known. In this study, we created three stable human colorectal adenocarcinoma Caco-2 cell lines exhibiting normal, low or high mTORC1 kinase activity, and used these cells to investigate the consequences of manipulating mTORC1 activity on enterocyte differentiation and chylomicron-like particle production. Constitutively active mTORC1 induced Caco-2 cell proliferation and differentiation (as judged by alkaline phosphatase activity) but weakened transepithelial electrical resistance (TEER). Repressed mTORC1 activity due to the knockdown of RPTOR significantly decreased the expression of lipogenic genes FASN, DGAT1 and DGAT2, lipoprotein assembly genes APOB and MTTP, reduced protein expression of APOB, MTTP and FASN, downregulated the gene expression of very long-chain fatty acyl-CoA ligase (FATP2), acyl-CoA binding protein (DBI), and prechylomicron transport vesicle-associated proteins VAMP7 (vesicle-associated membrane protein 7) and SAR1B (secretion associated Ras related GTPase 1B) resulting in the repression of apoB-containing triacylglycerol-rich lipoprotein secretion. Exposure of Caco-2 cells harboring a constitutively active mTORC1 to short-chain fatty acid derivatives, R-α-lipoic acid and 4-phenylbutyric acid, downregulated chylomicron-like particle secretion by interfering with the lipidation and assembly of the particles, and concomitantly repressed mTORC1 activity with no change to Raptor abundance or PRAS40 (Thr246) phosphorylation. R-α-lipoic acid and 4-phenylbutyric acid may be useful to mitigate intestinal lipoprotein overproduction and associated postprandial inflammation.

The Multi-Faceted Role of Autophagy During Animal Virus Infection

Autophagy is a process of degradation to maintain cellular homeostatic by lysosomes, which ensures cellular survival under various stress conditions, including nutrient deficiency, hypoxia, high temperature, and pathogenic infection. Xenophagy, a form of selective autophagy, serves as a defense mechanism against multiple intracellular pathogen types, such as viruses, bacteria, and parasites. Recent years have seen a growing list of animal viruses with autophagy machinery. Although the relationship between autophagy and human viruses has been widely summarized, little attention has been paid to the role of this cellular function in the veterinary field, especially today, with the growth of serious zoonotic diseases. The mechanisms of the same virus inducing autophagy in different species, or different viruses inducing autophagy in the same species have not been clarified. In this review, we examine the role of autophagy in important animal viral infectious diseases and discuss the regulation mechanisms of different animal viruses to provide a potential theoretical basis for therapeutic strategies, such as targets of new vaccine development or drugs, to improve industrial production in farming.

Autophagy Modulators in Coronavirus Diseases: A Double Strike in Viral Burden and Inflammation

Coronaviruses are the etiologic agents of several diseases. Coronaviruses of critical medical importance are characterized by highly inflammatory pathophysiology, involving severe pulmonary impairment and infection of multiple cell types within the body. Here, we discuss the interplay between coronaviruses and autophagy regarding virus life cycle, cell resistance, and inflammation, highlighting distinct mechanisms by which autophagy restrains inflammatory responses, especially those involved in coronavirus pathogenesis. We also address different autophagy modulators available and the rationale for drug repurposing as an attractive adjunctive therapy. We focused on pharmaceuticals being tested in clinical trials with distinct mechanisms but with autophagy as a common target. These autophagy modulators act in cell resistance to virus infection and immunomodulation, providing a double-strike to prevent or treat severe disease development and death from coronaviruses diseases.

GFAT2 mediates cardiac hypertrophy through HBP-O-GlcNAcylation-Akt pathway

Molecular mechanisms mediating cardiac hypertrophy by glucose metabolism are incompletely understood. Hexosamine biosynthesis pathway (HBP), an accessory pathway of glycolysis, is known to be involved in the attachment of O-linked N-acetylglucosamine motif (O-GlcNAcylation) to proteins, a post-translational modification. We here demonstrate that glutamine-fructose-6-phosphate amidotransferase 2 (GFAT2), a critical HBP enzyme, is a major isoform of GFAT in the heart and is increased in response to several hypertrophic stimuli, including isoproterenol (ISO). Knockdown of GFAT2 suppresses ISO-induced cardiomyocyte hypertrophy, accompanied by suppression of Akt O-GlcNAcylation and activation. Knockdown of GFAT2 does not affect anti-hypertrophic effect by Akt inhibition. Administration of glucosamine, a substrate of HBP, induces protein O-GlcNAcylation, Akt activation, and cardiomyocyte hypertrophy. In mice, 6-diazo-5-oxo-L-norleucine, an inhibitor of GFAT, attenuates ISO-induced protein O-GlcNAcylation, Akt activation, and cardiac hypertrophy. Our results demonstrate that GFAT2 mediates cardiomyocyte hypertrophy by HBP-O-GlcNAcylation-Akt pathway and could be a critical therapeutic target of cardiac hypertrophy.

Restraint upon Embryonic Metatarsal Ex Vivo Growth by Hydrogel Reveals Interaction between Quasi-Static Load and the mTOR Pathway

Mechanical cues play a vital role in limb skeletal development, yet their influence and underpinning mechanisms in the regulation of endochondral ossification (EO) processes are incompletely defined. Furthermore, interactions between endochondral growth and mechanics and the mTOR/NF-ĸB pathways are yet to be explored. An appreciation of how mechanical cues regulate EO would also clearly be beneficial in the context of fracture healing and bone diseases, where these processes are recapitulated. The study herein addresses the hypothesis that the mTOR/NF-ĸB pathways interact with mechanics to control endochondral growth. To test this, murine embryonic metatarsals were incubated ex vivo in a hydrogel, allowing for the effects of quasi-static loading on longitudinal growth to be assessed. The results showed significant restriction of metatarsal growth under quasi-static loading during a 14-day period and concentration-dependent sensitivity to hydrogel-related restriction. This study also showed that hydrogel-treated metatarsals retain their viability and do not present with increased apoptosis. Metatarsals exhibited reversal of the growth-restriction when co-incubated with mTOR compounds, whilst it was found that these compounds showed no effects under basal culture conditions. Transcriptional changes linked to endochondral growth were assessed and downregulation of Col2 and Acan was observed in hydrogel-treated metatarsi at day 7. Furthermore, cell cycle analyses confirmed the presence of chondrocytes exhibiting S-G2/M arrest. These data indicate that quasi-static load provokes chondrocyte cell cycle arrest, which is partly overcome by mTOR, with a less marked interaction for NF-ĸB regulators.

Insulin/IGF-1 signaling promotes immunosuppression via the STAT3 pathway: impact on the aging process and age-related diseases

BACKGROUND

The insulin/IGF-1 signaling pathway has a major role in the regulation of longevity both in Caenorhabditis elegans and mammalian species, i.e., reduced activity of this pathway extends lifespan, whereas increased activity accelerates the aging process. The insulin/IGF-1 pathway controls protein and energy metabolism as well as the proliferation and differentiation of insulin/IGF-1-responsive cells. Insulin/IGF-1 signaling also regulates the functions of the innate and adaptive immune systems. The purpose of this review was to elucidate whether insulin/IGF-1 signaling is linked to immunosuppressive STAT3 signaling which is known to promote the aging process.

METHODS

Original and review articles encompassing the connections between insulin/IGF-1 and STAT3 signaling were examined from major databases including Pubmed, Scopus, and Google Scholar.

RESULTS

The activation of insulin/IGF-1 receptors stimulates STAT3 signaling through the JAK and AKT-driven signaling pathways. STAT3 signaling is a major activator of immunosuppressive cells which are able to counteract the chronic low-grade inflammation associated with the aging process. However, the activation of STAT3 signaling stimulates a negative feedback response through the induction of SOCS factors which not only inhibit the activity of insulin/IGF-1 receptors but also that of many cytokine receptors. The inhibition of insulin/IGF-1 signaling evokes insulin resistance, a condition known to be increased with aging. STAT3 signaling also triggers the senescence of both non-immune and immune cells, especially through the activation of p53 signaling.

CONCLUSIONS

Given that cellular senescence, inflammaging, and counteracting immune suppression increase with aging, this might explain why excessive insulin/IGF-1 signaling promotes the aging process.

Protein Phosphorylation Signaling Cascades in Autism: The Role of mTOR Pathway

The mammalian target of rapamycin (mTOR) signaling pathway is a central regulator of cell metabolism, growth, and survival in response to hormones, growth factors, nutrients, and stress-induced signals. In this review, we analyzed the studies on the molecular abnormalities of the mTOR-associated signaling cascades in autism spectrum disorders (ASDs) and outlined the prospects for the pathogenicity-targeting pharmacotherapeutic approaches to ASDs, in particular syndromic ASDs. Based on available experimental and clinical data, we suggest that very early detection of molecular abnormalities in the ASD risk groups can be facilitated by using peripheral blood platelets. Also, identification of the time window of critical dysregulations in the described pathways in the ASD risk groups might suggest further research directions leading to more efficacious pharmacotherapeutic interventions in ASDs.

Targeting autophagy in disease: established and new strategies

Macroautophagy/autophagy is an evolutionarily conserved pathway responsible for clearing cytosolic aggregated proteins, damaged organelles or invading microorganisms. Dysfunctional autophagy leads to pathological accumulation of the cargo, which has been linked to a range of human diseases, including neurodegenerative diseases, infectious and autoimmune diseases and various forms of cancer. Cumulative work in animal models, application of genetic tools and pharmacologically active compounds, has suggested the potential therapeutic value of autophagy modulation in disease, as diverse as Huntington, Salmonella infection, or pancreatic cancer. Autophagy activation versus inhibition strategies are being explored, while the role of autophagy in pathophysiology is being studied in parallel. However, the progress of preclinical and clinical development of autophagy modulators has been greatly hampered by the paucity of selective pharmacological agents and biomarkers to dissect their precise impact on various forms of autophagy and cellular responses. Here, we summarize established and new strategies in autophagy-related drug discovery and indicate a path toward establishing a more efficient discovery of autophagy-selective pharmacological agents. With this knowledge at hand, modern concepts for therapeutic exploitation of autophagy might become more plausible.

Abbreviations: ALS: amyotrophic lateral sclerosis; AMPK: AMP-activated protein kinase; ATG: autophagy-related gene; AUTAC: autophagy-targeting chimera; CNS: central nervous system; CQ: chloroquine; GABARAP: gamma-aminobutyric acid type A receptor-associated protein; HCQ: hydroxychloroquine; LYTAC: lysosome targeting chimera; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MTOR: mechanistic target of rapamycin kinase; NDD: neurodegenerative disease; PDAC: pancreatic ductal adenocarcinoma; PE: phosphatidylethanolamine; PIK3C3/VPS34: phosphatidylinositol 3-kinase catalytic subunit type 3; PtdIns3K: class III phosphatidylinositol 3-kinase; PtdIns3P: phosphatidylinositol 3-phosphate; PROTAC: proteolysis-targeting chimera; SARS-CoV-2: severe acute respiratory syndrome coronavirus 2; SQSTM1/p62: sequestosome 1; ULK1: unc-51 like autophagy activating kinase 1.

Feedback, Crosstalk and Competition: Ingredients for Emergent Non-Linear Behaviour in the PI3K/mTOR Signalling Network

The PI3K/mTOR signalling pathway plays a central role in the governing of cell growth, survival and metabolism. As such, it must integrate and decode information from both external and internal sources to guide efficient decision-making by the cell. To facilitate this, the pathway has evolved an intricate web of complex regulatory mechanisms and elaborate crosstalk with neighbouring signalling pathways, making it a highly non-linear system. Here, we describe the mechanistic biological details that underpin these regulatory mechanisms, covering a multitude of negative and positive feedback loops, feed-forward loops, competing protein interactions, and crosstalk with major signalling pathways. Further, we highlight the non-linear and dynamic network behaviours that arise from these regulations, uncovered through computational and experimental studies. Given the pivotal role of the PI3K/mTOR network in cellular homeostasis and its frequent dysregulation in pathologies including cancer and diabetes, a coherent and systems-level understanding of the complex regulation and consequential dynamic signalling behaviours within this network is imperative for advancing biology and development of new therapeutic approaches.

BAFF signaling in B cell metabolism

BAFF is an essential cytokine primarily known for its role in maintaining B cell homeostasis via induction of a pro-survival gene expression profile. Additionally, recent evidence suggests that BAFF induced signaling also drives a metabolic program that is needed for homeostatic cell mass maintenance in resting B cells and which increases the cells' capacity to divide. Many components of the signaling cascades initiated by BAFF, the alternative NFκB pathway and the PI3K/AKT/mTOR pathway, are active in roles beyond their classically assigned function. These components can directly or indirectly impact metabolic reprogramming. Further exploration of the role BAFF signaling plays in B cell metabolism could help to identify metabolic vulnerabilities of hyperactive B cells in the context of autoimmunity.

NOXA-mediated degradation of MCL1 and BCL2L1 causes apoptosis of daunorubicin-treated human acute myeloid leukemia cells

Daunorubicin (DNR) is used clinically to treat acute myeloid leukemia (AML), while the signaling pathways associated with its cytotoxicity are not fully elucidated. Thus, we investigated the DNR-induced death pathway in the human AML cell lines U937 and HL-60. DNR-induced apoptosis in U937 cells accompanied by downregulation of MCL1 and BCL2L1, upregulation of Phorbol-12-myristate-13-acetate-induced protein 1 (NOXA), and mitochondrial depolarization. DNR induced NOX4-mediated reactive reactive oxygen species (ROS) production, which in turn inactivated Akt and simultaneously activated p38 mitogen-activated protein kinase (MAPK). Activated p38 MAPK and inactivated Akt coordinately increased GSK3β-mediated cAMP response element-binding protein (CREB) phosphorylation, which promoted NOXA transcription. NOXA upregulation critically increased the proteasomal degradation of MCL1 and BCL2L1. The same pathway was also responsible for the DNR-induced death of HL-60 cells. Restoration of MCL1 or BCL2L1 expression alleviated DNR-induced mitochondrial depolarization and cell death. Furthermore, ABT-199 (a BCL2 inhibitor) synergistically enhanced the cytotoxicity of DNR in AML cell lines. Notably, DNR-induced DNA damage was not related to NOXA-mediated degradation of MCL1 and BCL2L1. Collectively, these results indicate that the upregulation of NOXA expression through the NOX4-ROS-p38 MAPK-GSK3β-CREB axis results in the degradation of MCL1 and BCL2L1 in DNR-treated U937 and HL-60 cells. This signaling pathway may provide insights into the mechanism underlying DNR-triggered apoptosis in AML cells.

Evaluating a New Class of AKT/mTOR Activators for HIV Latency Reversing Activity Ex Vivo and In Vivo

An ability to activate latent HIV-1 expression could benefit many HIV cure strategies, but the first generation of latency reversing agents (LRAs) has proven disappointing. We evaluated AKT/mTOR activators as a potential new class of LRAs. Two glycogen synthase kinase-3 inhibitors (GSK-3i's), SB-216763 and tideglusib (the latter already in phase II clinical trials) that activate AKT/mTOR signaling were tested. These GSK-3i's reactivated latent HIV-1 present in blood samples from aviremic individuals on antiretroviral therapy (ART) in the absence of T cell activation, release of inflammatory cytokines, cell toxicity, or impaired effector function of cytotoxic T lymphocytes or NK cells. However, when administered in vivo to SIV-infected rhesus macaques on suppressive ART, tideglusib exhibited poor pharmacodynamic properties and resulted in no clear evidence of significant SIV latency reversal. Whether alternative pharmacological formulations or combinations of this drug with other classes of LRAs will lead to an effective in vivo latency-reversing strategy remains to be determined.IMPORTANCE If combined with immune therapeutics, latency reversing agents (LRAs) have the potential to reduce the size of the reservoir sufficiently that an engineered immune response can control the virus in the absence of antiretroviral therapy. We have identified a new class of LRAs that do not induce T-cell activation and that are able to potentiate, rather than inhibit, CD8+ T and NK cell cytotoxic effector functions. This new class of LRAs corresponds to inhibitors of glycogen synthase kinase-3. In this work, we have also studied the effects of one member of this drug class, tideglusib, in SIV-infected rhesus monkeys. When tested in vivo, however, tideglusib showed unfavorable pharmacokinetic properties, which resulted in lack of SIV latency reversal. The disconnect between our ex vivo and in vivo results highlights the importance of developing next generation LRAs with pharmacological properties that allow systemic drug delivery in relevant anatomical compartments harboring latent reservoirs.

Effects of different branched-chain amino acids supplementation protocols on the inflammatory response of LPS-stimulated RAW 264.7 macrophages

Although branched-chain amino acids (BCAA) are commonly used as a strategy to recover nutritional status of critically ill patients, recent findings on their role as immunonutrients have been associated with unfavorable outcomes, especially in obese patients. The present study aimed to explore the effects of different BCAA supplementation protocols in the inflammatory response of LPS-stimulated RAW 264.7 macrophages. Cell cultures were divided into five groups, with and without BCAA supplementation, (2 mmol/L of each amino acid). Then, cell cultures followed three different treatment protocols, consisting of a pretreatment (PT), an acute treatment (AT), and a chronic treatment (CT) with BCAA and LPS stimulation (1 µg/mL). Cell viability was analyzed by MTT assay, NO production was assessed by the Griess reaction and IL-6, IL-10, TNF-α and PGE2 synthesis, was evaluated by ELISA. BCAA significantly increased cell viability in AT and CT protocols, and NO and IL-10 synthesis in all treatment protocols. IL-6 synthesis was only increased in PT and CT protocols. TNF-α and PGE2 synthesis were not altered in any of the protocols and groups. BCAA supplementation was able to increase both pro and anti-inflammatory mediators synthesis by RAW 264.7 macrophages, which was influenced by the protocol applied. Moreover, these parameters were significantly increased by isoleucine supplementation, highlighting a potential research field for future studies.

Oxidative Stress and the Intersection of Oncogenic Signaling and Metabolism in Squamous Cell Carcinomas

Squamous cell carcinomas (SCCs) arise from both stratified squamous and non-squamous epithelium of diverse anatomical sites and collectively represent one of the most frequent solid tumors, accounting for more than one million cancer deaths annually. Despite this prevalence, SCC patients have not fully benefited from recent advances in molecularly targeted therapy or immunotherapy. Rather, decades old platinum-based or radiation regimens retaining limited specificity to the unique characteristics of SCC remain first-line treatment options. Historically, a lack of a consolidated perspective on genetic aberrations driving oncogenic transformation and other such factors essential for SCC pathogenesis and intrinsic confounding cellular heterogeneity in SCC have contributed to a critical dearth in effective and specific therapies. However, emerging evidence characterizing the distinct genomic, epigenetic, and metabolic landscapes of SCC may be elucidating unifying features in a seemingly heterogeneous disease. In this review, by describing distinct metabolic alterations and genetic drivers of SCC revealed by recent studies, we aim to establish a conceptual framework for a previously unappreciated network of oncogenic signaling, redox perturbation, and metabolic reprogramming that may reveal targetable vulnerabilities at their intersection.

Expanding the View of IKK: New Substrates and New Biology

The inhibitor of kappa B kinase (IKK) family consists of IKKα, IKKβ, and the IKK-related kinases TBK1 and IKKε. These kinases are considered master regulators of inflammation and innate immunity via their control of the transcription factors NF-κB, IRF3, and IRF7. Novel phosphorylated substrates have been attributed to these kinases, a subset of which is not directly related to either inflammation or innate immunity. These findings have greatly expanded the perspectives on the biological activities of these kinases. In this review we highlight some of the novel substrates for this kinase family and discuss the biological implications of these phosphorylation events.

mTORC1 silencing during intestinal epithelial Caco-2 cell differentiation is mediated by the activation of the AMPK/TSC2 pathway

The mechanistic target of rapamycin complex 1 (mTORC1) signaling is the prototypical pathway regulating protein synthesis and cell proliferation. The level of mTORC1 activity is high in intestinal stem cells located at the base of the crypts and thought to gradually decrease as transit-amplifying cells migrate out of the crypts and differentiate into enterocytes, goblet cells or enteroendocrine cells along the epithelium. The unknown mechanism responsible for the silencing of intestinal epithelium mTORC1 during cell differentiation was investigated in Caco-2 cells, which spontaneously differentiate into enterocytes in standard growth medium. The results show that TSC2, an upstream negative regulator of mTORC1 was central to mTORC1 silencing in differentiated Caco-2 cells. AMPK-mediated activation of TSC2 (Ser1387) and repression of Raptor (Ser792), an essential component of mTORC1, were stimulated in differentiated Caco-2 cells. ERK1/2-mediated repression of TSC2 (Ser664) seen in undifferentiated Caco-2 cells was lifted in differentiated cells. IRS-1-mediated activation of AKT (Thr308) phosphorylation was stimulated in differentiated Caco-2 cells and may be involved in cross-pathway repression of ERK1/2. Additionally, PRAS40 (Thr246) phosphorylation was decreased in differentiated Caco-2 cells compared to undifferentiated cells allowing dephosphorylated PRAS40 to displace Raptor thereby repressing mTORC1 kinase activity.

The emerging role of Wnt5a in the promotion of a pro-inflammatory and immunosuppressive tumor microenvironment

Wnt5a is the prototypical activator of the non-canonical Wnt pathways, and its overexpression has been implicated in the progression of several tumor types by promoting cell motility, invasion, EMT, and metastasis. Recent evidences have revealed a novel role of Wnt5a in the phosphorylation of the NF-κB subunit p65 and the activation of the NF-κB pathway in cancer cells. In this article, we review the molecular mechanisms and mediators defining a Wnt5a/NF-κB signaling pathway and propose that the aberrant expression of Wnt5a in some tumors drives a Wnt5a/NF-κB/IL-6/STAT3 positive feedback loop that amplifies the effects of Wnt5a. The evidences discussed here suggest that Wnt5a has a double effect on the tumor microenvironment. First, it activates an autocrine ROR1/Akt/p65 pathway that promotes inflammation and chemotaxis of immune cells. Then, Wnt5a activates a TLR/MyD88/p50 pathway exclusively in myelomonocytic cells promoting the synthesis of the anti-inflammatory cytokine IL-10 and a tolerogenic phenotype. As a result of these mechanisms, Wnt5a plays a negative role on immune cell function that contributes to an immunosuppressive tumor microenvironment and would contribute to resistance to immunotherapy. Finally, we summarized the development of different strategies targeting either Wnt5a or the Wnt5a receptor ROR1 that can be helpful for cancer therapy by contributing to generate a more immunostimulatory tumor microenvironment.

Hypoxic Transformation of Immune Cell Metabolism Within the Microenvironment of Oral Cancers

Oral squamous cell carcinoma (OSCC) includes tumors of the lips, tongue, gingivobuccal complex, and floor of the mouth. Prognosis for OSCC is highly heterogeneous, with overall 5-year survival of ~50%, but median survival of just 8-10 months for patients with locoregional recurrence or metastatic disease. A key feature of OSCC is microenvironmental oxygen depletion due to rapid growth of constituent tumor cells, which triggers hypoxia-associated signaling events and metabolic adaptations that influence subsequent tumor progression. Better understanding of leukocyte responses to tissue hypoxia and onco-metabolite expression under low-oxygen conditions will therefore be essential to develop more effective methods of diagnosing and treating patients with OSCC. This review assesses recent literature on metabolic reprogramming, redox homeostasis, and associated signaling pathways that mediate crosstalk of OSCC with immune cells in the hypoxic tumor microenvironment. The likely functional consequences of this metabolic interface between oxygen-starved OSCC and infiltrating leukocytes are also discussed. The hypoxic microenvironment of OSCC modifies redox signaling and alters the metabolic profile of tumor-infiltrating immune cells. Improved understanding of heterotypic interactions between host leukocytes, tumor cells, and hypoxia-induced onco-metabolites will inform the development of novel theranostic strategies for OSCC.

Oxidative Stress and Cancer Development: Are Noncoding RNAs the Missing Links?

Significance: It is now clear that genetic changes underlie the basis of cancer, and alterations in functions of multiple genes are responsible for the process of tumorigenesis. Besides the classical genes that are usually implicated in cancer, the role of noncoding RNAs (ncRNAs) and reactive oxygen species (ROS) as independent entitites has also been investigated. Recent Advances: The microRNAs and long noncoding RNAs (lncRNAs), two main classes of ncRNAs, are known to regulate many aspects of tumor development. ROS, generated during oxidative stress and pathological conditions, are known to regulate every step of tumor development. Conversely, oxidative stress and ROS producing agents can suppress tumor development. The malignant cells normally produce high levels of ROS compared with normal cells. The interaction between ROS and ncRNAs regulates the expression of multiple genes and pathways implicated in cancer, suggesting a unique mechanistic relationship among ncRNA-ROS-cancer. The mechanistic relationship has been reported in hepatocellular carcinoma, glioma, and malignancies of blood, breast, colorectum, esophagus, kidney, lung, mouth, ovary, pancreas, prostate, and stomach. The ncRNA-ROS regulate several cancer-related cell signaling pathways, namely, protein kinase B (AKT), epidermal growth factor receptor (EGFR), forkhead box O3 (FOXO3), kelch-like ECH-associated protein 1 (Keap1), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), nuclear factor erythroid 2-related factor 2 (Nrf2), p53, phosphatase and tensin homologue (PTEN), and wingless-related integration site (Wnt)/glycogen synthase kinase-3 beta (GSK3β). Critical Issues: To date, most of the reports about ncRNA-oxidative stress-carcinogenesis relationships are based on cell lines. The mechanistic basis for this relationship has not been completely elucidated. Future Directions: Attempts should be made to explore the association of lncRNAs with ROS. The significance of the ncRNA-oxidative stress-carcinogenesis interplay should also be explored through studies in animal models.

Curcumin represses mTORC1 signaling in Caco-2 cells by a two-sided mechanism involving the loss of IRS-1 and activation of AMPK

The mechanistic target of rapamycin complex 1 (mTORC1) is a central modulator of inflammation and tumorigenesis in the gastrointestinal tract. Growth factors upregulate mTORC1 via the PI3K/AKT and/or Ras/MAPK signal pathways. Curcumin (CUR), a polyphenol found in turmeric roots (Curcuma longa) can repress mTORC1 kinase activity in colon cancer cell lines; however, key aspects of CUR mechanism of action remain to be elucidated including its primary cellular target. We investigated the molecular effects of physiologically attainable concentration of CUR (20 μM) in the intestinal lumen on mTORC1 signaling in Caco-2 cells. CUR markedly inhibited mTORC1 kinase activity as determined by the decreased phosphorylation of p70S6K (Thr389, -99%, P < 0.0001) and S6 (Ser235/236, -92%, P < 0.0001). Mechanistically, CUR decreased IRS-1 protein abundance (-80%, P < 0.0001) thereby downregulating AKT phosphorylation (Ser473, -94%, P < 0.0001) and in turn PRAS40 phosphorylation (Thr246, -99%, P < 0.0001) while total PRAS40 abundance was unchanged. The use of proteasome inhibitor MG132 showed that CUR-mediated loss of IRS-1 involved proteasomal degradation. CUR lowered Raptor protein abundance, which combined with PRAS40 hypophosphorylation, suggests CUR repressed mTORC1 activity by inducing compositional changes that hinder the complex assembly. In addition, CUR activated AMPK (Thr172 phosphorylation, P < 0.0001), a recognized repressor of mTORC1, and AMPK upstream regulator LKB1. Although cargo adapter protein p62 was decreased by CUR (-49%, P < 0.004), CUR did not significantly induce autophagy. Inhibition of AKT/mTORC1 signaling by CUR may have lifted the cross-inhibition onto MAPK signaling, which became induced; p-ERK1/2 (+670%, P < 0.0001), p-p38 (+1433%, P < 0.0001). By concomitantly targeting IRS-1 and AMPK, CUR's mechanism of mTORC1 inhibition is distinct from that of rapamycin.

WNK1 regulates uterine homeostasis and its ability to support pregnancy

WNK1 (with no lysine [K] kinase 1) is an atypical kinase protein ubiquitously expressed in humans and mice. A mutation in its encoding gene causes hypertension in humans, which is associated with abnormal ion homeostasis. WNK1 is critical for in vitro decidualization in human endometrial stromal cells, thereby demonstrating its importance in female reproduction. Using a mouse model, WNK1 was ablated in the female reproductive tract to define its in vivo role in uterine biology. Loss of WNK1 altered uterine morphology, causing endometrial epithelial hyperplasia, adenomyotic features, and a delay in embryo implantation, ultimately resulting in compromised fertility. Combining transcriptomic, proteomic, and interactomic analyses revealed a potentially novel regulatory pathway whereby WNK1 represses AKT phosphorylation through protein phosphatase 2A (PP2A) in endometrial cells from both humans and mice. We show that WNK1 interacted with PPP2R1A, the alpha isoform of the PP2A scaffold subunit. This maintained the levels of PP2A subunits and stabilized its activity, which then dephosphorylated AKT. Therefore, loss of WNK1 reduced PP2A activity, causing AKT hypersignaling. Using FOXO1 as a readout of AKT activity, we demonstrate that there was escalated FOXO1 phosphorylation and nuclear exclusion, leading to a disruption in the expression of genes that are crucial for embryo implantation.

Tumor-Induced Metabolism and T Cells Located in Tumor Environment

Several subtypes of T cells are located in a tumor environment, each of which supplies their energy using different metabolic mechanisms. Since the cancer cells require high levels of glucose, the conditions of food poverty in the tumor environment can cause inactivation of immune cells, especially the T-effector cells, due to the need for glucose in the early stages of these cells activity. Different signaling pathways, such as PI3K-AKt-mTOR, MAPK, HIF-1α, etc., are activated or inactivated by the amount and type of energy source or oxygen levels that determine the fate of T cells in a cancerous environment. This review describes the metabolites in the tumor environment and their effects on the function of T cells. It also explains the signaling pathway of T cells in the tumor and normal conditions, due to the level of access to available metabolites and subtypes of T cells in the tumor environment.

Regulation of mTORC1 by Upstream Stimuli

The mammalian target of rapamycin (mTOR) is an evolutionary conserved Ser/Thr protein kinase that senses multiple upstream stimuli to control cell growth, metabolism, and autophagy. mTOR is the catalytic subunit of mTOR complex 1 (mTORC1). A significant amount of research has uncovered the signaling pathways regulated by mTORC1, and the involvement of these signaling cascades in human diseases like cancer, diabetes, and ageing. Here, we review advances in mTORC1 regulation by upstream stimuli. We specifically focus on how growth factors, amino acids, G-protein coupled receptors (GPCRs), phosphorylation, and small GTPases regulate mTORC1 activity and signaling.

Metabolic Role of PTEN in Insulin Signaling and Resistance

Phosphatase and tensin homolog (PTEN) is most prominently known for its function in tumorigenesis. However, a metabolic role of PTEN is emerging as a result of its altered expression in type 2 diabetes (T2D), which results in impaired insulin signaling and promotion of insulin resistance during the pathogenesis of T2D. PTEN functions in regulating insulin signaling across different organs have been identified. Through the use of a variety of models, such as tissue-specific knockout (KO) mice and in vitro cell cultures, PTEN's role in regulating insulin action has been elucidated across many cell types. Herein, we will review the recent advancements in the understanding of PTEN's metabolic functions in each of the tissues and cell types that contribute to regulating systemic insulin sensitivity and discuss how PTEN may represent a promising therapeutic strategy for treatment or prevention of T2D.

Polyphyllin I Promoted Melanoma Cells Autophagy and Apoptosis via PI3K/Akt/mTOR Signaling Pathway

To investigate whether Polyphyllin I (PPI) might induce the autophagy and apoptosis of melanoma cells by regulating PI3K/Akt/mTOR signal pathway. Melanoma A375 cells were incubated with different concentrations of Polyphyllin I (0, 1.5, 3.0, and 6.0 mg/L) and PI3K/Akt/mTOR signaling pathway activator IGF-1(20 mg/L). CCK-8 assay was utilized to detect cell proliferation; Cell apoptosis and cell cycle were measured by flow cytometry; Western blot was used to examine the expressions of proteins. Immunofluorescence analysis was performed to evaluate autophagy of A375 cells; In addition, xenograft-bearing nude mice were applied to study the role of Polyphyllin I on melanoma development, melanoma cell proliferation, as well as melanoma cell apoptosis in vivo. The outcomes represented that Polyphyllin I promoted A375 cell apoptosis via upregulating Bax level and cleaved caspase-3 level and downregulating Bcl-2 level, inhibited the growth of A375 cells at the G0/G1 phase, and enhanced cell autophagy via regulating the levels of Beclin 1, LC3II, and p62. However, IGF-1 (an activator of PI3K/Akt/mTOR signal pathway) attenuated these changes that Polyphyllin I induced. Furthermore, the xenograft model experiment confirmed that Polyphyllin I treatment suppressed xenograft tumor growth, increased apoptotic index evaluated by the TUNEL method, and reduced the level of Ki67 in tumor tissues in vivo. In conclusion, Polyphyllin I treatment enhanced melanoma cell autophagy and apoptosis, as well as blocked melanoma cell cycle via suppressing PI3K/Akt/mTOR signal pathway. Meanwhile, Polyphyllin I treatment suppressed the development of melanoma in vivo. Therefore, Polyphyllin I possibly is a promising molecular targeted agent used in melanoma therapy.