The Target of Rapamycin and Mechanisms of Cell Growth

Inhibitory effects of medium-chain fatty acids on the proliferation of human breast cancer cells via suppression of Akt/mTOR pathway and modulating the Bcl-2 family protein

Medium-chain fatty acids (MCFAs) have 6-12 carbon atoms and are instantly absorbed into the bloodstream before traveling to the portal vein and the liver, where they are immediately used for energy and may have antitumor effects. Its role in breast cancer is poorly understood. To investigate the apoptosis-inducing effect of MCFAs in breast cancer cells, cell viability assay, colony formation assay, cell migration assay, cell invasion assay, nuclear morphology, cell cycle assay, intracellular reactive oxygen species (ROS), matrix metalloproteinase (MMP), apoptosis, RT-qPCR analysis, and Western blot analysis were performed. In the present study, MCFA treatments reduced proliferative capability, increased ROS level, increased the depletion of MMP, induced G0/G1 and S phase cell cycle arrest, and late apoptosis of breast cancer cells in an effective concentration. Besides, MCFA treatment contributed to the upregulation of proapoptotic protein (BAK) and caspase-3, and the downregulation of antiapoptotic protein (Bcl-2). Mechanistically, phosphorylation levels of EGFR, Akt, and mTOR were significantly reduced in breast cancer cells treated with MCFAs. However, no significant changes in apoptosis and signaling-related proteins were observed in lauric acid-treated ER-positive cancer cells. Our findings suggested that MCFAs suppressed breast cancer cell proliferation by modulating the PI3K/Akt/mTOR signaling pathway. MCFAs may be a promising therapeutic drug for treating breast cancer.

MORG1 limits mTORC1 signaling by inhibiting Rag GTPases

Autophagy, an important quality control and recycling process vital for cellular homeostasis, is tightly regulated. The mTORC1 signaling pathway regulates autophagy under conditions of nutrient availability and scarcity. However, how mTORC1 activity is fine-tuned during nutrient availability to allow basal autophagy is unclear. Here, we report that the WD-domain repeat protein MORG1 facilitates basal constitutive autophagy by inhibiting mTORC1 signaling through Rag GTPases. Mechanistically, MORG1 interacts with active Rag GTPase complex inhibiting the Rag GTPase-mediated recruitment of mTORC1 to the lysosome. MORG1 depletion in HeLa cells increases mTORC1 activity and decreases autophagy. The autophagy receptor p62/SQSTM1 binds to MORG1, but MORG1 is not an autophagy substrate. However, p62/SQSTM1 binding to MORG1 upon re-addition of amino acids following amino acid's depletion precludes MORG1 from inhibiting the Rag GTPases, allowing mTORC1 activation. MORG1 depletion increases cell proliferation and migration. Low expression of MORG1 correlates with poor survival in several important cancers.

A Chemically Inducible Organelle Rerouting Assay to Probe Primary Cilium Assembly, Maintenance, and Disassembly in Cultured Cells

The primary cilium is a conserved, microtubule-based organelle that protrudes from the surface of most vertebrate cells as well as sensory cells of many organisms. It transduces extracellular chemical and mechanical cues to regulate diverse cellular processes during development and physiology. Loss-of-function studies via RNA interference and CRISPR/Cas9-mediated gene knockouts have been the main tool for elucidating the functions of proteins, protein complexes, and organelles implicated in cilium biology. However, these methods are limited in studying acute spatiotemporal functions of proteins as well as the connection between their cellular positioning and functions. A powerful approach based on inducible recruitment of plus or minus end-directed molecular motors to the protein of interest enables fast and precise control of protein activity in time and in space. In this chapter, we present a chemically inducible heterodimerization method for functional perturbation of centriolar satellites, an emerging membrane-less organelle involved in cilium biogenesis and function. The method we present is based on rerouting of centriolar satellites to the cell center or the periphery in mammalian epithelial cells. We also describe how this method can be applied to study the temporal functions of centriolar satellites during primary cilium assembly, maintenance, and disassembly.

Stabilizing Immature Dendritic Spines in the Auditory Cortex: A Key Mechanism for mTORC1-Mediated Enhancement of Long-Term Fear Memories

Mammalian target of rapamycin (mTOR) pathway has emerged as a key molecular mechanism underlying memory processes. Although mTOR inhibition is known to block memory processes, it remains elusive whether and how an enhancement of mTOR signaling may improve memory processes. Here we found in male mice that the administration of VO-OHpic, an inhibitor of the phosphatase and tensin homolog (PTEN) that negatively modulates AKT-mTOR pathway, enhanced auditory fear memory for days and weeks, while it left short-term memory unchanged. Memory enhancement was associated with a long-lasting increase in immature-type dendritic spines of pyramidal neurons into the auditory cortex. The persistence of spine remodeling over time arose by the interplay between PTEN inhibition and memory processes, as VO-OHpic induced only a transient immature spine growth in the somatosensory cortex, a region not involved in long-term auditory memory. Both the potentiation of fear memories and increase in immature spines were hampered by rapamycin, a selective inhibitor of mTORC1. These data revealed that memory can be potentiated over time by the administration of a selective PTEN inhibitor. In addition to disclosing new information on the cellular mechanisms underlying long-term memory maintenance, our study provides new insights on the molecular processes that aid enhancing memories over time.SIGNIFICANCE STATEMENT The neuronal mechanisms that may help improve the maintenance of long-term memories are still elusive. The inhibition of mammalian-target of rapamycin (mTOR) signaling shows that this pathway plays a crucial role in synaptic plasticity and memory formation. However, whether its activation may strengthen long-term memory storage is unclear. We assessed the consequences of positive modulation of AKT-mTOR pathway obtained by VO-OHpic administration, a phosphatase and tensin homolog inhibitor, on memory retention and underlying synaptic modifications. We found that mTOR activation greatly enhanced memory maintenance for weeks by producing a long-lasting increase of immature-type dendritic spines in pyramidal neurons of the auditory cortex. These results offer new insights on the cellular and molecular mechanisms that can aid enhancing memories over time.

CRISPR-mediated reversion of oncogenic KRAS mutation results in increased proliferation and reveals independent roles of Ras and mTORC2 in the migration of A549 lung cancer cells

Although the RAS oncogene has been extensively studied, new aspects concerning its role and regulation in normal biology and cancer continue to be discovered. Recently, others and we have shown that the mechanistic Target of Rapamycin Complex 2 (mTORC2) is a Ras effector in Dictyostelium and mammalian cells. mTORC2 plays evolutionarily conserved roles in cell survival and migration and has been linked to tumorigenesis. Because RAS is often mutated in lung cancer, we investigated whether a Ras-mTORC2 pathway contributes to enhancing the migration of lung cancer cells expressing oncogenic Ras. We used A549 cells and CRISPR/Cas9 to revert the cells' KRAS G12S mutation to wild-type and establish A549 revertant (REV) cell lines, which we then used to evaluate the Ras-mediated regulation of mTORC2 and cell migration. Interestingly, our results suggest that K-Ras and mTORC2 promote A549 cell migration but as part of different pathways and independently of Ras's mutational status. Moreover, further characterization of the A549REV cells revealed that loss of mutant K-Ras expression for the wild-type protein leads to an increase in cell growth and proliferation, suggesting that the A549 cells have low KRAS-mutant dependency and that recovering expression of wild-type K-Ras protein increases these cells tumorigenic potential.

Formulation of cost-effective medium and optimization studies for enhanced production of rapamycin

BACKGROUND

Enhancing rapamycin production using a cost-effective medium is crucial for wider accessibility, reduced manufacturing costs, sustainable pharmaceutical practices, and advancements in therapeutic applications. It promotes global health, biotechnological innovation, research collaboration, and societal well-being through affordable and effective treatments. This study focuses on the development of a novel cost-effective production medium for the synthesis of rapamycin from Streptomyces hygroscopicus.

RESULTS

In the initial screening, more rapamycin production was observed in medium A. Initially, the organism produced 10 µg/mL rapamycin. Based on the OFT results, a novel cost-effective medium composition was designed, incorporating soyabean, sugarcane juice, and dried tomato components. Using RSM, soyabean and tomato was found to be more significant in rapamycin production than sugarcane. In the optimized medium, the production of rapamycin increased significantly to 24 µg/mL. Furthermore, a comparative analysis of the growth kinetics between the production normal medium (referred to as production medium A) and the newly optimized cost-effective production medium revealed that the optimized cost-effective production medium significantly enhanced the production of rapamycin.

CONCLUSION

Overall, this study demonstrates the successful development of a cost-effective production medium for rapamycin synthesis from S. hygroscopicus. The findings highlight the potential of using a cost-effective medium to enhance the production of a valuable secondary metabolite, rapamycin, while reducing production costs.

Muscle Protein Synthesis with a Hybrid Dairy and Plant-Based Protein Blend (P4) Is Equal to Whey Protein in a Murine Ageing Model after Fasting

P4, a specific combination of dairy proteins (whey and casein) and plant-based protein isolates (pea and soy), has been shown to provide a more balanced amino acid (AA) profile than its single constituent proteins; however, less is known about how this translates to muscle protein synthesis (MPS). The aim of this study was to investigate the effect of P4 compared to whey or casein against fasted control on MPS. C57BL/6J mice, aged 25 months, were fasted overnight, followed by oral gavage of either whey, P4, casein, or water as a fasted control. Thirty minutes after ingestion, puromycin (0.04 µmol∙g^-1 bodyweight) was subcutaneously injected; 30-min thereafter, mice were sacrificed. MPS was measured by the SUnSET method, and signalling proteins were determined in the left-tibialis anterior (TA) muscle by the WES technique. AA composition was determined in plasma and right-TA muscle. Dried blood spots (DBS) were analysed for postprandial AA dynamics at 10, 20, 45, 60 min. MPS was 1.6-fold increased with whey (p = 0.006) and 1.5-fold with P4 compared to fasted (p = 0.008), while no change was seen with casein. This was confirmed by a significant increase of phosphorylated/total ratio of 4E-BP1 for both whey (p = 0.012) and P4 (p = 0.001). No changes were observed in p70S6K and mTOR phosphorylation/total ratio with whey or P4. Intramuscular leucine levels were lower for P4 (0.71 µmol∙g dry weight^-1) compared to whey (0.97 µmol∙g dry weight^-1) (p = 0.0007). Ten minutes postprandial, DBS showed significantly increased blood AA levels of BCAAs, histidine, lysine, threonine, arginine, and tyrosine for P4 versus fasted. In conclusion, a hybrid mix of dairy and plant-based proteins (P4) resulted in a MPS response that was similar to whey protein in aged mice after fasting. This suggests that other anabolic triggers beyond leucine or the well-balanced amino acid profile and bioavailability of the blend benefit stimulation of MPS.

Transcriptomic Analysis of the Effect of Torin-2 on the Central Nervous System of Drosophila melanogaster

Torin-2, a synthetic compound, is a highly selective inhibitor of both TORC1 and TORC2 (target of rapamycin) complexes as an alternative to the well-known immunosuppressor, geroprotector, and potential anti-cancer natural compound rapamycin. Torin-2 is effective at hundreds of times lower concentrations and prevents some negative side effects of rapamycin. Moreover, it inhibits the rapamycin-resistant TORC2 complex. In this work, we evaluated transcriptomic changes in D. melanogaster heads induced with lifetime diets containing Torin-2 and suggested possible neuroprotective mechanisms of Torin-2. The analysis included D. melanogaster of three ages (2, 4, and 6 weeks old), separately for males and females. Torin-2, taken at the lowest concentration being tested (0.5 μM per 1 L of nutrient paste), had a slight positive effect on the lifespan of D. melanogaster males (+4% on the average) and no positive effect on females. At the same time, RNA-Seq analysis revealed interesting and previously undiscussed effects of Torin-2, which differed between sexes as well as in flies of different ages. Among the cellular pathways mostly altered by Torin-2 at the gene expression level, we identified immune response, protein folding (heat shock proteins), histone modification, actin cytoskeleton organization, phototransduction and sexual behavior. Additionally, we revealed that Torin-2 predominantly reduced the expression of Srr gene responsible for the conversion of L-serine to D-serine and thus regulating activity of NMDA receptor. Via western blot analysis, we showed than in old males Torin-2 tends to increase the ratio of the active phosphorylated form of ERK, the lowest node of the MAPK cascade, which may play a significant role in neuroprotection. Thus, the complex effect of Torin-2 may be due to the interplay of the immune system, hormonal background, and metabolism. Our work is of interest for further research in the field of NMDA-mediated neurodegeneration.

Crosstalk between phytochemicals and inflammatory signaling pathways

Novel bioactive constituents from natural sources are actively being investigated. The phytochemicals in these phenolic compounds are believed to have a variety of beneficial effects on human health. Several phenolic compounds have been found in plants. The antioxidant potential of phenols has been discussed in numerous studies along with their anti-inflammatory effects on pro-inflammatory cytokine, inducible cyclooxygenase-2, and nitric oxide synthase. Through current study, an attempt is made to outline and highlight a wide variety of inflammation-associated signaling pathways that have been modified by several natural compounds. These signaling pathways include nuclear factor-kappa B (NF-кB), activator protein (AP)-1, protein tyrosine kinases (PTKs), mitogen-activated protein kinases (MAPKs), nuclear factor erythroid 2-related factor 2 (Nrf2) transcription factors, tyrosine phosphatidylinositol 3-kinase (PI3K)/AKT, and the ubiquitin-proteasome system. In light of the influence of natural substances on signaling pathways, their impact on the production of inflammatory mediator is highlighted in this review.

Circular RNA circDLG1 (has_circ_0068706) functions as an oncogene in nonsmall cell lung cancer through regulating AKT/mTOR signaling and direct binding to miR-144

Nonsmall cell lung cancer (NSCLC) is a major subtype of lung cancer, causing substantial cancer-related deaths worldwide. However, the molecular basis of NSCLC development and progression remains understudied. Recently, a circular RNA, circDLG1, has been implicated in carcinogenesis and cancer metastasis. Yet, how circDLG1 affects NSCLC progression has not been reported. Here this study aims to elucidate the role of circDLG1 in NSCLC. First, we found that circDLG1 was significantly upregulated in both the GEO dataset and NSCLC tissues. Next, we silenced the expression of circDLG1 in NSCLC cell lines. Knockdown of circDLG1 upregulated miR-144 and downregulated Protein kinase B (AKT)/mechanistic target of rapamycin (mTOR), resulting in suppression of the proliferation activity and metastasis ability of NSCLC. In addition, circDLG1 knockdown significantly decreased the expression of the mesenchymal markers, proliferating cell nuclear antigen (PCNA), and N-cadherin, while increasing the expression level of E-cadherin. In conclusion, we demonstrate that circDLG1 promotes the pathogenesis and progression of NSCLC by regulating the miR-144/AKT/mTOR signaling axis, providing potential diagnostic and therapeutic targets for designing innovative treatment strategies.

Potential of Capric Acid in Neurological Disorders: An Overview

To solve the restrictions of a classical ketogenic diet, a modified medium-chain triglyceride diet was introduced which required only around 60% of dietary energy. Capric acid (CA), a small molecule, is one of the main components because its metabolic profile offers itself as an alternate source of energy to the brain in the form of ketone bodies. This is possible with the combined capability of CA to cross the blood-brain barrier and achieve a concentration of 50% concentration in the brain more than any other fatty acid in plasma. Natural sources of CA include vegetable oils such as palm oil and coconut oil, mammalian milk and some seeds. Several studies have shown that CA has varied action on targets that include AMPA receptors, PPAR-γ, inflammatory/oxidative stress pathways and gut dysbiosis. Based on these lines of evidence, CA has proved to be effective in the amelioration of neurological diseases such as epilepsy, affective disorders and Alzheimer's disease. But these studies still warrant more pre-clinical and clinical studies that would further prove its efficacy. Hence, to understand the potential of CA in brain disease and associated comorbid conditions, an advance and rigorous molecular mechanistic study, apart from the reported in-vitro/in-vivo studies, is urgently required for the development of this compound through clinical setups.

Ras-mediated activation of mTORC2 promotes breast epithelial cell migration and invasion

We previously identified the mechanistic target of rapamycin complex 2 (mTORC2) as an effector of Ras for the control of directed cell migration in Dictyostelium. Recently, the Ras-mediated regulation of mTORC2 was found to be conserved in mammalian cells, and mTORC2 was shown to be an effector of oncogenic Ras. Interestingly, mTORC2 has been linked to cancer cell migration, and particularly in breast cancer. Here, we investigated the role of Ras in promoting the migration and invasion of breast cancer cells through mTORC2. We observed that both Ras and mTORC2 promote the migration of different breast cancer cells and breast cancer cell models. Using HER2 and oncogenic Ras-transformed breast epithelial MCF10A cells, we found that both wild-type Ras and oncogenic Ras promote mTORC2 activation and an mTORC2-dependent migration and invasion in these breast cancer models. We further observed that, whereas oncogenic Ras-transformed MCF10A cells display uncontrolled cell proliferation and invasion, disruption of mTORC2 leads to loss of invasiveness only. Together, our findings suggest that, whereas the Ras-mediated activation of mTORC2 is expected to play a minor role in breast tumor formation, the Ras-mTORC2 pathway plays an important role in promoting the migration and invasion of breast cancer cells.

Delineation of proteome changes driven by cell size and growth rate

Increasing cell size drives changes to the proteome, which affects cell physiology. As cell size increases, some proteins become more concentrated while others are diluted. As a result, the state of the cell changes continuously with increasing size. In addition to these proteomic changes, large cells have a lower growth rate (protein synthesis rate per unit volume). That both the cell’s proteome and growth rate change with cell size suggests they may be interdependent. To test this, we used quantitative mass spectrometry to measure how the proteome changes in response to the mTOR inhibitor rapamycin, which decreases the cellular growth rate and has only a minimal effect on cell size. We found that large cell size and mTOR inhibition, both of which lower the growth rate of a cell, remodel the proteome in similar ways. This suggests that many of the effects of cell size are mediated by the size-dependent slowdown of the cellular growth rate. For example, the previously reported size-dependent expression of some senescence markers could reflect a cell’s declining growth rate rather than its size per se. In contrast, histones and other chromatin components are diluted in large cells independently of the growth rate, likely so that they remain in proportion with the genome. Finally, size-dependent changes to the cell’s growth rate and proteome composition are still apparent in cells continually exposed to a saturating dose of rapamycin, which indicates that cell size can affect the proteome independently of mTORC1 signaling. Taken together, our results clarify the dependencies between cell size, growth, mTOR activity, and the proteome remodeling that ultimately controls many aspects of cell physiology.

Research Progress on the Regulation Mechanism of Key Signal Pathways Affecting the Prognosis of Glioma

As is known to all, glioma, a global difficult problem, has a high malignant degree, high recurrence rate and poor prognosis. We analyzed and summarized signal pathway of the Hippo/YAP, PI3K/AKT/mTOR, miRNA, WNT/β-catenin, Notch, Hedgehog, TGF-β, TCS/mTORC1 signal pathway, JAK/STAT signal pathway, MAPK signaling pathway, the relationship between BBB and signal pathways and the mechanism of key enzymes in glioma. It is concluded that Yap1 inhibitor may become an effective target for the treatment of glioma in the near future through efforts of generation after generation. Inhibiting PI3K/Akt/mTOR, Shh, Wnt/β-Catenin, and HIF-1α can reduce the migration ability and drug resistance of tumor cells to improve the prognosis of glioma. The analysis shows that Notch1 and Sox2 have a positive feedback regulation mechanism, and Notch4 predicts the malignant degree of glioma. In this way, notch cannot only be treated for glioma stem cells in clinic, but also be used as an evaluation index to evaluate the prognosis, and provide an exploratory attempt for the direction of glioma treatment. MiRNA plays an important role in diagnosis, and in the treatment of glioma, VPS25, KCNQ1OT1, KB-1460A1.5, and CKAP4 are promising prognostic indicators and a potential therapeutic targets for glioma, meanwhile, Rheb is also a potent activator of Signaling cross-talk etc. It is believed that these studies will help us to have a deeper understanding of glioma, so that we will find new and better treatment schemes to gradually conquer the problem of glioma.

Research Progress on the Regulation Mechanism of Key Signal Pathways Affecting the Prognosis of Glioma

As is known to all, glioma, a global difficult problem, has a high malignant degree, high recurrence rate and poor prognosis. We analyzed and summarized signal pathway of the Hippo/YAP, PI3K/AKT/mTOR, miRNA, WNT/β-catenin, Notch, Hedgehog, TGF-β, TCS/mTORC1 signal pathway, JAK/STAT signal pathway, MAPK signaling pathway, the relationship between BBB and signal pathways and the mechanism of key enzymes in glioma. It is concluded that Yap1 inhibitor may become an effective target for the treatment of glioma in the near future through efforts of generation after generation. Inhibiting PI3K/Akt/mTOR, Shh, Wnt/β-Catenin, and HIF-1α can reduce the migration ability and drug resistance of tumor cells to improve the prognosis of glioma. The analysis shows that Notch1 and Sox2 have a positive feedback regulation mechanism, and Notch4 predicts the malignant degree of glioma. In this way, notch cannot only be treated for glioma stem cells in clinic, but also be used as an evaluation index to evaluate the prognosis, and provide an exploratory attempt for the direction of glioma treatment. MiRNA plays an important role in diagnosis, and in the treatment of glioma, VPS25, KCNQ1OT1, KB-1460A1.5, and CKAP4 are promising prognostic indicators and a potential therapeutic targets for glioma, meanwhile, Rheb is also a potent activator of Signaling cross-talk etc. It is believed that these studies will help us to have a deeper understanding of glioma, so that we will find new and better treatment schemes to gradually conquer the problem of glioma.

The TSC Complex-mTORC1 Axis: From Lysosomes to Stress Granules and Back

The tuberous sclerosis protein complex (TSC complex) is a key integrator of metabolic signals and cellular stress. In response to nutrient shortage and stresses, the TSC complex inhibits the mechanistic target of rapamycin complex 1 (mTORC1) at the lysosomes. mTORC1 is also inhibited by stress granules (SGs), RNA-protein assemblies that dissociate mTORC1. The mechanisms of lysosome and SG recruitment of mTORC1 are well studied. In contrast, molecular details on lysosomal recruitment of the TSC complex have emerged only recently. The TSC complex subunit 1 (TSC1) binds lysosomes via phosphatidylinositol-3,5-bisphosphate [PI(3,5)P2]. The SG assembly factors 1 and 2 (G3BP1/2) have an unexpected lysosomal function in recruiting TSC2 when SGs are absent. In addition, high density lipoprotein binding protein (HDLBP, also named Vigilin) recruits TSC2 to SGs under stress. In this mini-review, we integrate the molecular mechanisms of lysosome and SG recruitment of the TSC complex. We discuss their interplay in the context of cell proliferation and migration in cancer and in the clinical manifestations of tuberous sclerosis complex disease (TSC) and lymphangioleiomyomatosis (LAM).

mTORC1 Crosstalk With Stress Granules in Aging and Age-Related Diseases

The mechanistic target of rapamycin complex 1 (mTORC1) kinase is a master regulator of metabolism and aging. A complex signaling network converges on mTORC1 and integrates growth factor, nutrient and stress signals. Aging is a dynamic process characterized by declining cellular survival, renewal, and fertility. Stressors elicited by aging hallmarks such as mitochondrial malfunction, loss of proteostasis, genomic instability and telomere shortening impinge on mTORC1 thereby contributing to age-related processes. Stress granules (SGs) constitute a cytoplasmic non-membranous compartment formed by RNA-protein aggregates, which control RNA metabolism, signaling, and survival under stress. Increasing evidence reveals complex crosstalk between the mTORC1 network and SGs. In this review, we cover stressors elicited by aging hallmarks that impinge on mTORC1 and SGs. We discuss their interplay, and we highlight possible links in the context of aging and age-related diseases.

RNA interference of mTOR gene delays molting process in Eriocheir sinensis

mTOR is a typical and conserved serine/threonine protein kinase that regulates cell growth and metabolism of organisms. Molting is a fundamental biological process in Chinese mitten crab (Eriocheir sinensis) and is monitored by a series of genes and pathways. The structural and functional characteristics of EsmTOR was investigated to determine the role of mTOR in the molting process of. The intact CDS of EsmTOR is 7449 bp in length and encodes a polypeptide consisting of 2482 amino acids. EsmTOR was expressed in all eight tissues examined during the three molting stages (postmolt, intermolt andpremolt), with levels fluctuating significantly during the molting. RNA interference of EsmTOR significantly delayed molting, indicating that mTOR may be involved in the molting process of E. sinensis. Meanwhile, a substantial downregulation was observed for the expression of upstream genes involved in amino acid transport (EsSLC7A5 and EsVATB) and downstream genes promoting ribosomal protein synthesis (EsS6K1) in the mTOR signaling pathway, as well as typical molt-related genes (EsMIH and EsEcR) after EsmTOR RNAi treatment. In addition, EsRheb, a molecular marker for tissue growth, was also significantly down-regulated. This study suggests that EsmTOR plays a fundamental role in molting regulation through the SLC7A5-V-ATPase-mTORC1 gene network.

Phytochemicals from Ajwa dates pulp extract induce apoptosis in human triple-negative breast cancer by inhibiting AKT/mTOR pathway and modulating Bcl-2 family proteins

Ajwa dates (Phoenix dactylifera L.) have been described in traditional and alternative medicine to provide several health benefits, but their mechanism of apoptosis induction against human triple-negative breast cancer MDA-MB-231 cells remains to be investigated. In this study, we analyzed the phytoconstituents in ethanolic Ajwa Dates Pulp Extract (ADPE) by liquid chromatography-mass spectrometry (LC-MS) and investigated anticancer effects against MDA-MB-231 cells. LC-MS analysis revealed that ADPE contained phytocomponents belonging to classes such as carbohydrates, phenolics, flavonoids and terpenoids. MTT assay demonstrated statistically significant dose- and time-dependent inhibition of MDA-MB-231 cells with IC50 values of 17.45 and 16.67 mg/mL at 24 and 48 h, respectively. Hoechst 33342 dye and DNA fragmentation data showed apoptotic cell death while AO/PI and Annexin V-FITC data revealed cells in late apoptosis at higher doses of ADPE. More importantly, ADPE prompted reactive oxygen species (ROS) induced alterations in mitochondrial membrane potential (MMP) in ADPE treated MDA-MB-231 cells. Cell cycle analysis demonstrated that ADPE induced cell arrest in S and G2/M checkpoints. ADPE upregulated the p53, Bax and cleaved caspase-3, thereby leading to the downregulation of Bcl-2 and AKT/mTOR pathway. ADPE did not show any significant toxicity on normal human peripheral blood mononuclear cells which suggests its safe application to biological systems under study. Thus, ADPE has the potential to be used as an adjunct to the mainline of treatment against breast cancer.

Mass spectrometric investigations of caloric restriction mimetics

Caloric restriction (CR) is an innovative therapy used in tumor tissue and tumor model studies to promote cell death and decrease cell viability. Caloric restriction mimetics (CRMs) are a class of drugs that induce CR and starvation conditions within a cell. When used simultaneously with other chemotherapy agents, the effects are synergistic and effective at promoting tumor cell death. In this review, we discuss CRMs and their potential as cancer therapeutics. Firstly, we establish an overview of CR and its impacts on healthy and tumor cells. CR and CRM drugs have shown to decrease age-related diseases and can act as an anti-cancer agent. As it can be challenging for an individual to diligently stick to a diet that would induce CR, CRMs are even more desirable. Then, we discuss the drug class by highlighting three CRMs: resveratrol, (-)-hydroxycitric acid, and rapamycin. These CRMs are commonly known for their dietary effects, but the underlying mechanisms that drive cellular metabolic and proteomic changes show promise as a cancer therapeutic. Lastly, we highlight the use of mass spectrometry and proteomic techniques on experiments utilizing CRM drugs to understand the cellular pathways impacted by this drug class, leading to a better understanding of the anti-cancer properties and potentials of CRM.

Gefitinib Results in Robust Host-Directed Immunity Against Salmonella Infection Through Proteo-Metabolomic Reprogramming

The global rise of antibiotic-resistant strains of Salmonella has necessitated the development of alternative therapeutic strategies. Recent studies have shown that targeting host factors may provide an alternative approach for the treatment of intracellular pathogens. Host-directed therapy (HDT) modulates host cellular factors that are essential to support the replication of the intracellular pathogens. In the current study, we identified Gefitinib as a potential host directed therapeutic drug against Salmonella. Further, using the proteome analysis of Salmonella-infected macrophages, we identified EGFR, a host factor, promoting intracellular survival of Salmonella via mTOR-HIF-1α axis. Blocking of EGFR, mTOR or HIF-1α inhibits the intracellular survival of Salmonella within the macrophages and in mice. Global proteo-metabolomics profiling indicated the upregulation of host factors predominantly associated with ATP turn over, glycolysis, urea cycle, which ultimately promote the activation of EGFR-HIF1α signaling upon infection. Importantly, inhibition of EGFR and HIF1α restored both proteomics and metabolomics changes caused by Salmonella infection. Taken together, this study identifies Gefitinib as a host directed drug that holds potential translational values against Salmonella infection and might be useful for the treatment of other intracellular infections.

Lifetime Impact of Cow's Milk on Overactivation of mTORC1: From Fetal to Childhood Overgrowth, Acne, Diabetes, Cancers, and Neurodegeneration

The consumption of cow's milk is a part of the basic nutritional habits of Western industrialized countries. Recent epidemiological studies associate the intake of cow's milk with an increased risk of diseases, which are associated with overactivated mechanistic target of rapamycin complex 1 (mTORC1) signaling. This review presents current epidemiological and translational evidence linking milk consumption to the regulation of mTORC1, the master-switch for eukaryotic cell growth. Epidemiological studies confirm a correlation between cow's milk consumption and birthweight, body mass index, onset of menarche, linear growth during childhood, acne vulgaris, type 2 diabetes mellitus, prostate cancer, breast cancer, hepatocellular carcinoma, diffuse large B-cell lymphoma, neurodegenerative diseases, and all-cause mortality. Thus, long-term persistent consumption of cow's milk increases the risk of mTORC1-driven diseases of civilization. Milk is a highly conserved, lactation genome-controlled signaling system that functions as a maternal-neonatal relay for optimized species-specific activation of mTORC1, the nexus for regulation of eukaryotic cell growth, and control of autophagy. A deeper understanding of milk´s impact on mTORC1 signaling is of critical importance for the prevention of common diseases of civilization.

CrossTORC and WNTegration in Disease: Focus on Lymphangioleiomyomatosis

The mechanistic target of rapamycin (mTOR) and wingless-related integration site (Wnt) signal transduction networks are evolutionarily conserved mammalian growth and cellular development networks. Most cells express many of the proteins in both pathways, and this review will briefly describe only the key proteins and their intra- and extracellular crosstalk. These complex interactions will be discussed in relation to cancer development, drug resistance, and stem cell exhaustion. This review will also highlight the tumor-suppressive tuberous sclerosis complex (TSC) mutated, mTOR-hyperactive lung disease of women, lymphangioleiomyomatosis (LAM). We will summarize recent advances in the targeting of these pathways by monotherapy or combination therapy, as well as future potential treatments.

Finding new edges: systems approaches to MTOR signaling

Cells have evolved highly intertwined kinase networks to finely tune cellular homeostasis to the environment. The network converging on the mechanistic target of rapamycin (MTOR) kinase constitutes a central hub that integrates metabolic signals and adapts cellular metabolism and functions to nutritional changes and stress. Feedforward and feedback loops, crosstalks and a plethora of modulators finely balance MTOR-driven anabolic and catabolic processes. This complexity renders it difficult — if not impossible — to intuitively decipher signaling dynamics and network topology. Over the last two decades, systems approaches have emerged as powerful tools to simulate signaling network dynamics and responses. In this review, we discuss the contribution of systems studies to the discovery of novel edges and modulators in the MTOR network in healthy cells and in disease.

G3BPs tether the TSC complex to lysosomes and suppress mTORC1 signaling

Ras GTPase-activating protein-binding proteins 1 and 2 (G3BP1 and G3BP2, respectively) are widely recognized as core components of stress granules (SGs). We report that G3BPs reside at the cytoplasmic surface of lysosomes. They act in a non-redundant manner to anchor the tuberous sclerosis complex (TSC) protein complex to lysosomes and suppress activation of the metabolic master regulator mechanistic target of rapamycin complex 1 (mTORC1) by amino acids and insulin. Like the TSC complex, G3BP1 deficiency elicits phenotypes related to mTORC1 hyperactivity. In the context of tumors, low G3BP1 levels enhance mTORC1-driven breast cancer cell motility and correlate with adverse outcomes in patients. Furthermore, G3bp1 inhibition in zebrafish disturbs neuronal development and function, leading to white matter heterotopia and neuronal hyperactivity. Thus, G3BPs are not only core components of SGs but also a key element of lysosomal TSC-mTORC1 signaling.

Anti-Inflammatory Activity of Extracts and Pure Compounds Derived from Plants via Modulation of Signaling Pathways, Especially PI3K/AKT in Macrophages

The plant kingdom is a source of important therapeutic agents. Therefore, in this review, we focus on natural compounds that exhibit efficient anti-inflammatory activity via modulation signaling transduction pathways in macrophage cells. Both extracts and pure chemicals from different species and parts of plants such as leaves, roots, flowers, barks, rhizomes, and seeds rich in secondary metabolites from various groups such as terpenes or polyphenols were included. Selected extracts and phytochemicals control macrophages biology via modulation signaling molecules including NF-κB, MAPKs, AP-1, STAT1, STAT6, IRF-4, IRF-5, PPARγ, KLF4 and especially PI3K/AKT. Macrophages are important immune effector cells that take part in antigen presentation, phagocytosis, and immunomodulation. The M1 and M2 phenotypes are related to the production of pro- and anti-inflammatory agents, respectively. The successful resolution of inflammation mediated by M2, or failed resolution mediated by M1, may lead to tissue repair or chronic inflammation. Chronic inflammation is strictly related to several disorders. Thus, compounds of plant origin targeting inflammatory response may constitute promising therapeutic strategies.

SIRT1 Antagonizes Oxidative Stress in Diabetic Vascular Complication

Diabetic mellitus (DM) is a significant public health concern worldwide with an increased incidence of morbidity and mortality, which is particularly due to the diabetic vascular complications. Several pivotal underlying mechanisms are associated with vascular complications, including hyperglycemia, mitochondrial dysfunction, inflammation, and most importantly, oxidative stress. Oxidative stress triggers defective angiogenesis, activates pro-inflammatory pathways and causes long-lasting epigenetic changes to facilitate the development of vascular complications. Therefore, therapeutic interventions targeting oxidative stress are promising to manage diabetic vascular complications. Sirtuin1 (SIRT1), a class III histone deacetylase belonging to the sirtuin family, plays critical roles in regulating metabolism and ageing-related pathological conditions, such as vascular diseases. Growing evidence has indicated that SIRT1 acts as a sensing regulator in response to oxidative stress and attenuates vascular dysfunction via cooperating with adenosine-monophosphate-activated protein kinase (AMPK) to activate antioxidant signals through various downstream effectors, including peroxisome proliferator-activated receptor-gamma co-activator 1 (PGC-1α), forkhead transcription factors (FOXOs), and peroxisome proliferative-activated receptor α (PPARα). In addition, SIRT1 interacts with hydrogen sulfide (H2S), regulates NADPH oxidase, endothelial NO synthase, and mechanistic target of rapamycin (mTOR) to suppress oxidative stress. Furthermore, mRNA expression of sirt1 is affected by microRNAs in DM. In the current review, we summarize recent advances illustrating the importance of SIRT1 in antagonizing oxidative stress. We also discuss whether modulation of SIRT1 can serve as a therapeutic strategy to treat diabetic vascular complications.

Protective effects of rapamycin on the retinal vascular bed during the vaso-obliteration phase in mouse oxygen-induced retinopathy model

Retinopathy of prematurity (ROP) is a vision-threatening disorder characterized with retinal vaso-obliteration in phase 1 and pathological neovascularization (NV) in phase 2. However, there has been no effective and safe treatment for ROP. Current management is mainly focused on the reduction of abnormal NV in phase 2, and anti-vascular endothelial growth factor (VEGF) therapy is the first-line treatment, yet, with great risks of late recurrence and systemic side effects. It has been reported that the severity of vaso-obliteration in phase 1 largely influences subsequent NV, suggesting that it may be a promising target to develop novel treatments for ROP. Here, we investigated the therapeutic potential and safety of early rapamycin intervention in treating phase 1 ROP and possible underlying mechanisms using the mouse model of oxygen-induced retinopathy (OIR). We found that intravitreal injection of rapamycin at postnatal day 7 (P7) significantly reduced retinal avascular area, increased vascular density, and reversed the suppression of deep capillaries development in phase 1 of OIR mice. Rapamycin treatment not only reduced vascular apoptosis, but also promoted proliferation and tip cell functions. Additionally, rapamycin did not interfere with normal retinal vascular development. Further investigation showed that Ang1/Tie2 pathway might be involved in rapamycin's vascular protection in phase 1 OIR retinas. Moreover, early rapamycin treatment at P7 had long-term protective effects of reducing retinal NV and avascular area, as well as enhancing vascular maturity in phase 2 of OIR mice. Together, our data suggest that rapamycin may be a safe and promising strategy for early intervention of ROP.

PALMER: improving pathway annotation based on the biomedical literature mining with a constrained latent block model

Background

In systems biology, it is of great interest to identify previously unreported associations between genes. Recently, biomedical literature has been considered as a valuable resource for this purpose. While classical clustering algorithms have popularly been used to investigate associations among genes, they are not tuned for the literature mining data and are also based on strong assumptions, which are often violated in this type of data. For example, these approaches often assume homogeneity and independence among observations. However, these assumptions are often violated due to both redundancies in functional descriptions and biological functions shared among genes. Latent block models can be alternatives in this case but they also often show suboptimal performances, especially when signals are weak. In addition, they do not allow to utilize valuable prior biological knowledge, such as those available in existing databases.

Results

In order to address these limitations, here we propose PALMER, a constrained latent block model that allows to identify indirect relationships among genes based on the biomedical literature mining data. By automatically associating relevant Gene Ontology terms, PALMER facilitates biological interpretation of novel findings without laborious downstream analyses. PALMER also allows researchers to utilize prior biological knowledge about known gene-pathway relationships to guide identification of gene–gene associations. We evaluated PALMER with simulation studies and applications to studies of pathway-modulating genes relevant to cancer signaling pathways, while utilizing biological pathway annotations available in the KEGG database as prior knowledge.

Conclusions

We showed that PALMER outperforms traditional latent block models and it provides reliable identification of novel gene–gene associations by utilizing prior biological knowledge, especially when signals are weak in the biomedical literature mining dataset. We believe that PALMER and its relevant user-friendly software will be powerful tools that can be used to improve existing pathway annotations and identify novel pathway-modulating genes.

Defective cell proliferation is an attribute of overexpressed Notch1 receptor and impaired autophagy in Fanconi Anemia

Fanconi Anemia (FA) is an inherited bone marrow failure syndrome caused by mutation in FA pathway proteins, involved in Interstrand Cross Link (ICL) repair. FA cells exhibit in vitro proliferation arrest due to accumulated DNA damage, hence understanding the rescue mechanism that renders proliferation advantage is required. Gene expression profiling performed in FA patients Peripheral Blood Mononuclear Cells (PBMCs) revealed a wide array of dysregulated biological processes. Functional enrichment and gene clustering analysis showed crippled autophagy process and escalated Notch signalling pathway in FA clinical samples and cell lines. Notch pathway mediators overexpression were reverted in FANCA mutant cells when treated with Rapamycin, an autophagy inducer. Additionally, Rapamycin stabilized cell viability after treatment with the DNA damaging agent, MitomycinC (MMC) and enhanced cell proliferation genes expression in FANCA mutant cells. Inherently FANCA mutant cells express impaired autophagy; thus activation of autophagy channelizes Notch signalling cascade and sustains cell viability.

Comprehensive analysis of mutations of renal cell carcinoma in an autosomal dominant polycystic kidney disease patient

Renal cell carcinoma (RCC) is known to be more prevalent in autosomal dominant polycystic kidney disease (ADPKD) patients than in the general population. However, little is known about genetic alterations or changes in signaling pathways in RCC in patients with ADPKD.In the current report, whole-exome and transcriptome sequencing was performed for paired samples of tumor tissue, cyst tissue, and peripheral blood (triple set) from a patient diagnosed with ADPKD and RCC.A 68-year-old man with ADPKD underwent left partial nephrectomy and was diagnosed with RCC. DNA and RNA were extracted from the triple set of the patient. A nonsense mutation in PKD2 (p.Arg742X), which is well known as a pathogenic variant in ADPKD, was identified in the paired triple set. In the tumor sample, a somatic missense mutation of VHL (p.S65L) was found, which is known as a pathogenic mutation in Von Hippel-Lindau syndrome and RCC. Furthermore, loss of chromosome 3p, where VHL is located, was detected. Upregulated VEGFA was found in the analysis of RCC mRNA, which might be caused by the loss of VHL and accelerate angiogenesis in RCC.Proliferation was also expected to be activated by the MAPK signaling pathway, including NRAS and MAPK1 expression.

Anti-fibrosis activity of quercetin attenuates rabbit tracheal stenosis via the TGF-β/AKT/mTOR signaling pathway

AIMS

This study aimed to explore the possible mechanism of trauma-induced laryngotracheal stenosis and potential protective and therapeutic efficacy of quercetin on trauma-induced laryngotracheal stenosis.

MAIN METHODS

The expression and activity of fibrotic factors [interleukin (IL)-6, IL-8, autophagy related 5 (ATG5), collagen (COL)-1, tumor growth factor (TGF)-β COL-3, microtubule-associated proteins 1A/1B light chain 3A (LC3), and vascular endothelial growth factor (VEGF)] and fibrotic signaling mediators [mammalian target of rapamycin (mTOR) and phosphorylated AKT (pAKT)] were detected by real-time quantitative PCR (qRT-PCR), ELISA, Western blot, and immunohistochemical staining, respectively, in the lipopolysaccharide (LPS)-induced WI-38 (a human embryonic lung fibroblast cell line) cellular fibrotic model and a trauma-induced rabbit tracheal stenosis model, with and without quercetin treatment.

KEY FINDINGS

Pre-treatment with quercetin significantly reversed the LPS-induced upregulation of pro-fibrotic factors (IL-6, IL-8, COL-1, COL-3, LC3) and fibrotic signaling mediators (mTOR and AKT), and it induced the downregulation of ATG5 in the WI-38 cells. Furthermore, the anti-fibrotic activity of quercetin was confirmed in the trauma-induced rabbit tracheal stenosis model. Thus, the nasogastric administration of quercetin attenuated the tracheal stenosis of the rabbit tracheal stenosis model, in addition to effectively reversing an increase in pro-fibrotic factors (VEGF, IL-6, TGF-β, COL-1, and COL-3) and fibrotic signaling mediators (mTOR and AKT), as well as downregulating ATG5 of the rabbit tracheal stenosis model.

SIGNIFICANCE

Quercetin exhibits anti-fibrotic activity by inhibiting pro-fibrotic factors and AKT/mTOR signaling pathway, in addition to activating autophagy activity. This study provided experimental evidence supporting the application of quercetin in tracheal stenosis, clinically.

Identification of Two Kinase Inhibitors with Synergistic Toxicity with Low-Dose Hydrogen Peroxide in Colorectal Cancer Cells in vitro

Colorectal carcinoma is among the most common types of cancers. With this disease, diffuse scattering in the abdominal area (peritoneal carcinosis) often occurs before diagnosis, making surgical removal of the entire malignant tissue impossible due to a large number of tumor nodules. Previous treatment options include radiation and its combination with intraperitoneal heat-induced chemotherapy (HIPEC). Both options have strong side effects and are often poor in therapeutic efficacy. Tumor cells often grow and proliferate dysregulated, with enzymes of the protein kinase family often playing a crucial role. The present study investigated whether a combination of protein kinase inhibitors and low-dose induction of oxidative stress (using hydrogen peroxide, H₂O₂) has an additive cytotoxic effect on murine, colorectal tumor cells (CT26). Protein kinase inhibitors from a library of 80 substances were used to investigate colorectal cancer cells for their activity, morphology, and immunogenicity (immunogenic cancer cell death, ICD) upon mono or combination. Toxic compounds identified in 2D cultures were confirmed in 3D cultures, and additive cytotoxicity was identified for the substances lavendustin A, GF109203X, and rapamycin. Toxicity was concomitant with cell cycle arrest, but except HMGB1, no increased expression of immunogenic markers was identified with the combination treatment. The results were validated for GF109203X and rapamycin but not lavendustin A in the 3D model of different colorectal (HT29, SW480) and pancreatic cancer cell lines (MiaPaca, Panc01). In conclusion, our in vitro data suggest that combining oxidative stress with chemotherapy would be conceivable to enhance antitumor efficacy in HIPEC.

Mechanistic target of rapamycin inhibitors: successes and challenges as cancer therapeutics

Delineating the contributions of specific cell signalling cascades to the development and maintenance of tumours has greatly informed our understanding of tumorigenesis and has advanced the modern era of targeted cancer therapy. It has been revealed that one of the key pathways regulating cell growth, the phosphatidylinositol 3-kinase/mechanistic target of rapamycin (PI3K/mTOR) signalling axis, is commonly dysregulated in cancer. With a specific, well-tolerated inhibitor of mTOR available, the impact of inhibiting this pathway at the level of mTOR has been tested clinically. This review highlights some of the promising results seen with mTOR inhibitors in the clinic and assesses some of the challenges that remain in predicting patient outcome following mTOR-targeted therapy.

Target of rapamycin signaling is tightly and differently regulated in the plant response under distinct abiotic stresses

TOR signaling is finely regulated under diverse abiotic stresses and may be required for the plant response with a different time-course depending on the duration and nature of the stress. Target of rapamycin (TOR) signaling is a central regulator of growth and development in eukaryotic organisms. However, its regulation under stress conditions has not yet been elucidated. In Arabidopsis, we show that TOR transcripts and activity in planta are finely regulated within hours after the onset of salt, osmotic, cold and oxidative stress. The expression of genes encoding the partner proteins of the TOR complex, RAPTOR3G and LST8-1, is also regulated. Besides, the data indicate that TOR activity increases at some time during the adverse condition. Interestingly, in oxidative stress, the major TOR activity increment occurred transiently at the early phase of treatment, while in salt, osmotic and cold stress, it was around 1 day after the unfavorable condition was applied. Those results suggest that the TOR signaling has an important role in the plant response to an exposure to stress. Moreover, basal ROS (H₂O₂) levels and their modification under abiotic stresses were altered in TOR complex mutants. On the other hand, the root phenotypic analysis of the effects caused by the diverse abiotic stresses on TOR complex mutants revealed that they were differently affected, being in some cases less sensitive, than wild-type plants to long-term unfavorable conditions. Therefore, in this work, we demonstrated that TOR signaling is tightly regulated under abiotic stresses, at transcript and activity level, with different and specific time-course patterns according to the type of abiotic stress in Arabidopsis. Taking our results together, we propose that TOR signaling should be necessary during the plant stress response.

Genomics Analysis of Metabolic Pathways of Human Stem Cell-Derived Microglia-Like Cells and the Integrated Cortical Spheroids

Brain spheroids or organoids derived from human pluripotent stem cells (hiPSCs) are still not capable of completely recapitulating in vivo human brain tissue, and one of the limitations is lack of microglia. To add built-in immune function, coculture of the dorsal forebrain spheroids with isogenic microglia-like cells (D-MG) was performed in our study. The three-dimensional D-MG spheroids were analyzed for their transcriptome and compared with isogenic microglia-like cells (MG). Cortical spheroids containing microglia-like cells displayed different metabolic programming, which may affect the associated phenotype. The expression of genes related to glycolysis and hypoxia signaling was increased in cocultured D-MG spheroids, indicating the metabolic shift to aerobic glycolysis, which is in favor of M1 polarization of microglia-like cells. In addition, the metabolic pathways and the signaling pathways involved in cell proliferation, cell death, PIK3/AKT/mTOR signaling, eukaryotic initiation factor 2 pathway, and Wnt and Notch pathways were analyzed. The results demonstrate the activation of mTOR and p53 signaling, increased expression of Notch ligands, and the repression of NF-κB and canonical Wnt pathways, as well as the lower expression of cell cycle genes in the cocultured D-MG spheroids. This analysis indicates that physiological 3-D microenvironment may reshape the immunity of in vitro cortical spheroids and better recapitulate in vivo brain tissue function for disease modeling and drug screening.

The Emerging Roles of mTORC1 in Macromanaging Autophagy

Autophagy is a process of self-degradation that enables the cell to survive when faced with starvation or stressful conditions. The mechanistic target of rapamycin (mTOR), also known as the mammalian target of rapamycin, plays a critical role in maintaining a balance between cellular anabolism and catabolism. mTOR complex 1 (mTORC1) was unveiled as a master regulator of autophagy since inhibition of mTORC1 was required to initiate the autophagy process. Evidence has emerged in recent years to indicate that mTORC1 also directly regulates the subsequent steps of the autophagy process, including the nucleation, autophagosome elongation, autophagosome maturation and termination. By phosphorylating select protein targets of the autophagy core machinery and/or their regulators, mTORC1 can alter their functions, increase their proteasomal degradation or modulate their acetylation status, which is a key switch of the autophagy process. Moreover, it phosphorylates and alters the subcellular localization of transcription factors to suppress the expression of genes needed for autophagosome formation and lysosome biogenesis. The purpose of this review article is to critically analyze current literatures to provide an integrated view of how mTORC1 regulates various steps of the autophagy process.

Endoplasmic reticulum-localized ECM1b suppresses tumor growth and regulates MYC and MTORC1 through modulating MTORC2 activation in esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is a deadly disease with dismal 5-year survival. Extracellular matrix protein 1 (ECM1) was identified as one of the most downregulated genes by transcriptomic analysis of normal esophageal/ESCC paired tissue samples. ECM1 plays oncogenic roles in cancer development in various cancer types. However, little is known about its role in ESCC. In vivo and in vitro functional assays coupled with analyses on public datasets and detailed molecular and mechanistic analyses were used to study the gene. We demonstrate that as opposed to the previously identified oncogenic role of ECM1a, ECM1b is a novel tumor suppressor in ESCC. ECM1 is significantly downregulated in ESCC and several other squamous cell carcinomas. ECM1b encodes a cellular protein that suppresses MYC protein expression and MTORC1 signaling activity. MTORC2 inactivation leads to suppressed MYC expression and MTORC1 signaling. ECM1b localizes to the endoplasmic reticulum and suppresses MTORC2 activation by inhibiting MTORC2/ribosome association. By regulating MTORC2/MYC/MTORC1 signaling, ECM1b suppresses general protein translation and enhances chemosensitivity. We provide evidence establishing a novel role of ECM1 in cancer that suggests ECM1b as a biomarker for ESCC disease management.

Phospho-mTOR expression in human glioblastoma microglia-macrophage cells

The glioblastoma (GBM) immune microenvironment is highly heterogeneous, and microglia may represent 30-70% of the entire tumor. However, the role of microglia and other specific immune populations is poorly characterized. Activation of mTOR signaling occurs in numerous human cancers and has roles in microglia-glioma cell interactions. We now show in human tumor specimens (42 patients), that 39% of tumor-associated microglial (TAM) cells express mTOR phosphorylated at Ser-2448; and similar mTOR activation is observed using a human microglia-glioma interaction paradigm. In addition, we confirm previous studies that microglia express urea and ARG1 (taken as M2 marker) in the presence of glioma cells, and this phenotype is down-regulated in the presence of a mTOR inhibitor. These results suggest that mTOR suppression in GBM patients might induce a reduction of the M2 phenotype expression in up to 40% of all TAMs. Since the M2 profile of microglial activation is believed to be associated with tumor progression, reductions in that phenotype may represent an additional anti-tumor mechanism of action of mTOR inhibitors, along with direct anti-proliferative activities.

Identification of Novel Components of Target-of-Rapamycin Signaling Pathway by Network-Based Multi-Omics Integrative Analysis

Target of rapamycin (TOR) is a major signaling pathway and regulator of cell growth. TOR serves as a hub of many signaling routes, and is implicated in the pathophysiology of numerous human diseases, including cancer, diabetes, and neurodegeneration. Therefore, elucidation of unknown components of TOR signaling that could serve as potential biomarkers and drug targets has a great clinical importance. In this study, our aim is to integrate transcriptomics, interactomics, and regulomics data in Saccharomyces cerevisiae using a network-based multiomics approach to enlighten previously unidentified, potential components of TOR signaling. We constructed the TOR-signaling protein interaction network, which was used as a template to search for TOR-mediated rapamycin and caffeine signaling paths. We scored the paths passing from at least one component of TOR Complex 1 or 2 (TORC1/TORC2) using the co-expression levels of the genes in the transcriptome data of the cells grown in the presence of rapamycin or caffeine. The resultant network revealed seven hitherto unannotated proteins, namely, Atg14p, Rim20p, Ret2p, Spt21p, Ylr257wp, Ymr295cp, and Ygr017wp, as potential components of TOR-mediated rapamycin and caffeine signaling in yeast. Among these proteins, we suggest further deciphering of the role of Ylr257wp will be particularly informative in the future because it was the only protein whose removal from the constructed network hindered the signal transduction to the TORC1 effector kinase Npr1p. In conclusion, this study underlines the value of network-based multiomics integrative data analysis in discovering previously unidentified components of the signaling networks by revealing potential components of TOR signaling for future experimental validation.

Use of topical rapamycin in the treatment of superficial lymphatic malformations

BACKGROUND

The superficial lymphatic component of vascular malformations poses a significant treatment challenge. It is responsible for the majority of symptoms presented, and to date, there is no consensus regarding treatment.

OBJECTIVE

To evaluate the effectiveness of topical rapamycin in treating superficial lymphatic malformations (LM).

METHODS

A case series study was performed of patients with superficial LM, treated with topical rapamycin. The clinical characteristics of patients and the concentration and application mode of the drug were recorded. The changes in the signs and symptoms observed and associated adverse effects were noted and analyzed.

RESULTS

The study population consisted of 11 patients of an average age of 10.5 years. All were treated with topical rapamycin: 6 patients with a 1% concentration, 1 with a 0.8% concentration, and 4 with a 0.4% concentration. Changes in the clinical appearance of the lesions were observed in all patients. The associated symptoms, present in 9 of 11 patients, improved in every case. The mean follow-up time was 16.1 months.

LIMITATIONS

This study is retrospective, with a small sample size and considerable heterogeneity of lesions and treatment approaches.

CONCLUSION

Treatment with topical rapamycin modifies the clinical appearance and alleviates symptoms of superficial LM.

Periostin in the Kidney

Periostin is a matricellular protein that is expressed in several tissues during embryonic development; however, its expression in adults is mostly restricted to collagen-rich connective tissues. Periostin is expressed only briefly during kidney development, but it is not normally detected in the adult kidney. Recent evidence has revealed that periostin is aberrantly expressed in several forms of chronic kidney disease (CKD), and that its expression correlates with the degree of interstitial fibrosis and the decline in renal function. Polycystic kidney disease (PKD), a genetic disorder, is characterized by the formation of numerous fluid-filled cysts in the kidneys. Periostin is secreted by the cyst epithelial cells and accumulates within the extracellular matrix adjacent to the cysts. In PKD mice, periostin overexpression accelerates cyst growth and contributes to structural changes in the kidneys, including interstitial fibrosis. Recent evidence suggests that periostin is a tissue repair molecule; however, its role in repair following acute kidney injury has not been investigated. It is thought that persistent expression of this protein in CKD contributes importantly to tubulointerstitial fibrosis and the progressive decline in renal function. Future studies to define the diverse actions of periostin during kidney injury may lead to effective therapies to slow PKD progression and possibly prevent the development of CKD. This chapter reviews the current literature on the expression of periostin in PKD and other forms of CKD, mechanisms for periostin stimulated cyst growth, its potential role in extracellular matrix production and renal fibrosis, and the evidence for periostin as a novel biomarker for kidney disease.

Curcumin alleviates rheumatoid arthritis-induced inflammation and synovial hyperplasia by targeting mTOR pathway in rats

PURPOSE

Rheumatoid arthritis (RA) is a chronic, progressive autoimmune disease characterized by aggressive and symmetric polyarthritis. Mammalian target of rapamycin (mTOR) was reported to be a new target for RA therapy and its inhibitor rapamycin can significantly reduce the invasive force of fibroblast-like synoviocytes. Here, we determined the effect of curcumin to alleviate inflammation and synovial hyperplasia for the therapy of RA.

MATERIALS AND METHODS

Collagen-induced arthritis (CIA) was developed in Wistar rats and used as a model resembling RA in humans. Rats were treated with curcumin (200 mg/kg) and the mTOR inhibitor rapamycin (2.5 mg/kg) daily for 3 weeks. Effects of the treatment on local joint, peripheral blood, and synovial hyperplasia in the pathogenesis of CIA were analyzed.

RESULTS

Curcumin and rapamycin significantly inhibited the redness and swelling of ankles and joints in RA rats. Curcumin inhibited the CIA-induced mTOR pathway and the RA-induced infiltration of inflammatory cells into the synovium. Curcumin and rapamycin treatment inhibited the increased levels of proinflammatory cytokines including IL-1β, TNF-α, MMP-1, and MMP-3 in CIA rats.

CONCLUSION

Our findings show that curcumin alleviates CIA-induced inflammation, synovial hyperplasia, and the other main features involved in the pathogenesis of CIA via the mTOR pathway. These results provide evidence for the anti-arthritic properties of curcumin and corroborate its potential use for the treatment of RA.

The Emerging Role of Insulin Receptor Isoforms in Thyroid Cancer: Clinical Implications and New Perspectives

Thyroid cancer (TC) is the most common endocrine tumor. Although the majority of TCs show good prognoses, a minor proportion are aggressive and refractory to conventional therapies. So far, the molecular mechanisms underlying TC pathogenesis are incompletely understood. Evidence suggests that TC cells and their precursors are responsive to insulin and insulin-like growth factors (IGFs), and often overexpress receptors for insulin (IR) and IGF-1 (IGF-1R). IR exists in two isoforms, namely IR-A and IR-B. The first binds insulin and IGF-2, unlike IR-B, which only binds insulin. IR-A is preferentially expressed in prenatal life and contributes to development through IGF-2 action. Aggressive TC overexpresses IR-A, IGF-2, and IGF-1R. The over-activation of IR-A/IGF-2 loop in TC is associated with stem-like features and refractoriness to some targeted therapies. Importantly, both IR isoforms crosstalk with IGF-1R, giving rise to the formation of hybrids receptors (HR-A or HR-B). Other interactions have been demonstrated with other molecules such as the non-integrin collagen receptor, discoidin domain receptor 1 (DDR1), and the receptor for the hepatocyte growth factor (HGF), Met. These functional networks provide mechanisms for IR signaling diversification, which may also exert a role in TC stem cell biology, thereby contributing to TC initiation and progression. This review focuses on the molecular mechanisms by which deregulated IR isoforms and their crosstalk with other molecules and signaling pathways in TC cells and their precursors may contribute to thyroid carcinogenesis, progression, and resistance to conventional treatments. We also highlight how targeting these alterations starting from TC progenitors cells may represent new therapeutic strategies to improve the clinical management of advanced TCs.

Ozone induces autophagy in rat chondrocytes stimulated with IL-1β through the AMPK/mTOR signaling pathway

Background

Ozone injection is generally used for the management of pain in diseases such as osteoarthritis (OA). Recent studies have shown that reduced autophagy in chondrocytes plays an important role in the development of OA. The purpose of this study was to determine whether ozone treats OA by inducing autophagy in OA chondrocytes.

Materials and methods

In this study, primary chondrocytes were stimulated with IL-1β for 24 hours to simulate an OA chondrocyte model, followed by treatment with ozone (30 µg/ mL) or pretreatment with 3-methyladenine or compound C before ozone treatment. Then, cell viability was detected by a CCK-8 kit, and the AMPK/mTOR signaling pathway and autophagy were detected by Western blotting and immunofluorescence. The mRNA expression levels of IL-6, TNF-α, MMP-13 and TIMP-1 were measured by quantitative real-time PCR. Finally, autophagosomes in chondrocytes were observed by transmission electron microscopy.

Results

Ozone improved cell viability in chondrocytes stimulated by IL-1β. The decreased level of autophagy in IL-1β-stimulated chondrocytes improved with ozone treatment through activation of the AMPK/mTOR signaling pathway. In addition, the mRNA expression levels of IL-6 and TNF-α were suppressed by ozone treatment in chondrocytes stimulated with IL-1β. Ozone increased the mRNA level of TIMP-1 and decreased the mRNA level of MMP-13 in chondrocytes stimulated with IL-1β.

Conclusion

These results suggested that ozone improved the decreased level of autophagy in chondrocytes stimulated with IL-1β through activation of the AMPK/mTOR signaling pathway. Moreover, ozone treatment suppressed inflammation and helped maintain metabolic balance in chondrocytes stimulated with IL-1β.

Energy Stress-Mediated Cytotoxicity in Tuberous Sclerosis Complex 2-Deficient Cells with Nelfinavir and Mefloquine Treatment

To find new anti-cancer drug therapies, we wanted to exploit homeostatic vulnerabilities within Tuberous Sclerosis Complex 2 (TSC2)-deficient cells with mechanistic target of rapamycin complex 1 (mTORC1) hyperactivity. We show that nelfinavir and mefloquine synergize to selectively evoke a cytotoxic response in TSC2-deficient cell lines with mTORC1 hyperactivity. We optimize the concentrations of nelfinavir and mefloquine to a clinically viable range that kill cells that lack TSC2, while wild-type cells tolerate treatment. This new clinically viable drug combination causes a significant level of cell death in TSC2-deficient tumor spheroids. Furthermore, no cell recovery was apparent after drug withdrawal, revealing potent cytotoxicity. Transcriptional profiling by RNA sequencing of drug treated TSC2-deficient cells compared to wild-type cells suggested the cytotoxic mechanism of action, involving initial ER stress and an imbalance in energy homeostatic pathways. Further characterization revealed that supplementation with methyl pyruvate alleviated energy stress and reduced the cytotoxic effect, implicating energy deprivation as the trigger of cell death. This work underpins a critical vulnerability with cancer cells with aberrant signaling through the TSC2-mTORC1 pathway that lack flexibility in homeostatic pathways, which could be exploited with combined nelfinavir and mefloquine treatment.

Chronic starvation induces noncanonical pro-death stress granules

Stress granules (SGs) assemble under stress-induced conditions that inhibit protein synthesis, including phosphorylation of eIF2α, inhibition of the RNA helicase eIF4a proteins or inactivation of mTORC1. Classically defined SGs are composed of translation initiation factors, 40S ribosomes, RNA-binding proteins and poly(A)+ mRNAs. As such, they represent an important compartment for storage of mRNAs and regulation of their translation. Emerging work on SGs indicates that these structures might promote cellular survival in diverse disease states. Yet, much work on SG formation and function employs acute stress conditions, which might not accurately reflect the chronic stresses that manifest in human disease. Here, we used prolonged nutrient starvation to model and investigate SG formation and function during chronic stress in a human cell line and mouse embryonic fibroblasts. Surprisingly, we found that SGs that form under chronic nutrient starvation lack 40S ribosomes, do not actively exchange their constituent components with cytoplasmic pools and promote cell death. We named these SGs starvation-induced SGs (stSGs). Our results on stSGs imply that SG assembly and function in the context of prolonged nutrient starvation stress differ significantly from what has been described for acute stress conditions.