mTOR Function Research Articles

DNA Damage, Transposable Element Expression and Their Associated Factors in Aging

Aging is a spontaneous and permanent physiological process that leads to declines in tissue and cell functions, along with an increased risk of developing various age-related diseases. The primary driving force associated with aging is the accumulation of damaged genetic material in the cell, such as DNA. DNA damage can be caused by endogenous and exogenous factors, which leads to genome instability, mitochondrial dysfunction, epigenetic modifications, and proteostatic disturb. Another driving force associated with aging is the disruption of cellular metabolism. This disruption is closely linked to alterations in the role of metabolic pathways, including insulin/IGF-1 and mTOR, which regulate crucial cellular processes like cell growth, cell proliferation, and apoptosis. The activation of the insulin/IGF-1 signaling pathway highly promotes cell growth and proliferation, while also inhibits autophagy and increasing ROS production. This ultimately leads to accelerated aging. Another crucial signaling pathway is the mTOR signaling pathway. It is responsible for detecting nutrient availability and controlling cell growth and metabolism. The dysregulation of mTOR function can lead to the development of neurodegenerative diseases, which are characterized by the aggregation of protein. Activation of transposable elements is the other driving force of aging, caused by changes in DNA methylation and the loss of heterochromatin. As a result, this leads to DNA damage, genomic instability, and inflammation. The aim of this review is to elucidate the consequence of DNA damage and other associated factors drive aging.

Relationship between ferroptosis and mitophagy in acute lung injury: a mini-review.

Acute lung injury (ALI) is one of the most deadly and prevalent diseases in the intensive care unit. Ferroptosis and mitophagy are pathological mechanisms of ALI. Ferroptosis aggravates ALI, whereas mitophagy regulates ALI. Ferroptosis and mitophagy are both closely related to reactive oxygen species (ROS). Mitophagy can regulate ferroptosis, but the specific relationship between ferroptosis and mitophagy is still unclear. This study summarizes previous research findings on ferroptosis and mitophagy, revealing their involvement in ALI. Examining the functions of mTOR and NLPR3 helps clarify the connection between ferroptosis and mitophagy in ALI, with the goal of establishing a theoretical foundation for potential therapeutic approaches in the future management of ALI.

Multi-omic signatures of sarcoidosis and progression in bronchoalveolar lavage cells

BackgroundSarcoidosis is a heterogeneous granulomatous disease with no accurate biomarkers of disease progression. Therefore, we profiled and integrated the DNA methylome, mRNAs, and microRNAs to identify molecular changes associated with sarcoidosis and disease progression that might illuminate underlying mechanisms of disease and potential biomarkers.MethodsBronchoalveolar lavage cells from 64 sarcoidosis subjects and 16 healthy controls were used. DNA methylation was profiled on Illumina HumanMethylationEPIC arrays, mRNA by RNA-sequencing, and miRNAs by small RNA-sequencing. Linear models were fit to test for effect of sarcoidosis diagnosis and progression phenotype, adjusting for age, sex, smoking, and principal components of the data. We built a supervised multi-omics model using a subset of features from each dataset.ResultsWe identified 1,459 CpGs, 64 mRNAs, and five miRNAs associated with sarcoidosis versus controls and four mRNAs associated with disease progression. Our integrated model emphasized the prominence of the PI3K/AKT1 pathway, which is important in T cell and mTOR function. Novel immune related genes and miRNAs including LYST, RGS14, SLFN12L, and hsa-miR-199b-5p, distinguished sarcoidosis from controls. Our integrated model also demonstrated differential expression/methylation of IL20RB, ABCC11, SFSWAP, AGBL4, miR-146a-3p, and miR-378b between non-progressive and progressive sarcoidosis.ConclusionsLeveraging the DNA methylome, transcriptome, and miRNA-sequencing in sarcoidosis BAL cells, we detected widespread molecular changes associated with disease, many which are involved in immune response. These molecules may serve as diagnostic/prognostic biomarkers and/or drug targets, although future testing is required for confirmation.

Nanoparticles for inducing Gaucher disease-like damage in cancer cells.

Nutrient avidity is one of the most distinctive features of tumours. However, nutrient deprivation has yielded limited clinical benefits. In Gaucher disease, an inherited metabolic disorder, cells produce cholesteryl-glucoside which accumulates in lysosomes and causes cell damage. Here we develop a nanoparticle (AbCholB) to emulate natural-lipoprotein-carried cholesterol and initiate Gaucher disease-like damage in cancer cells. AbCholB is composed of a phenylboronic-acid-modified cholesterol (CholB) and albumin. Cancer cells uptake the nanoparticles into lysosomes, where CholB reacts with glucose and generates a cholesteryl-glucoside-like structure that resists degradation and aggregates into microscale crystals, causing Gaucher disease-like damage in a glucose-dependent manner. In addition, the nutrient-sensing function of mTOR is suppressed. It is observed that normal cells escape severe damage due to their inferior ability to compete for nutrients compared with cancer cells. This work provides a bioinspired strategy to selectively impede the metabolic action of cancer cells by taking advantage of their nutrient avidity.

The mTOR Signaling Pathway and mTOR Inhibitors in Cancer: Next-generation Inhibitors and Approaches.

mTOR is a serine/threonine kinase that plays various roles in cell growth, proliferation, and metabolism. mTOR signaling in cancer becomes irregular. Therefore, drugs targeting mTOR have been developed. Although mTOR inhibitors rapamycin and rapamycin rapalogs (everolimus, rapamycin, temsirolimus, deforolimus, etc.) and new generation mTOR inhibitors (Rapalink, Dual PI3K/mTOR inhibitors, etc.) are used in cancer treatments, mTOR resistance mechanisms may inhibit the efficacy of these drugs. Therefore, new inhibition approaches are developed. Although these new inhibition approaches have not been widely investigated in cancer treatment, the use of nanoparticles has been evaluated as a new treatment option in a few types of cancer. This review outlines the functions of mTOR in the cancer process, its resistance mechanisms, and the efficiency of mTOR inhibitors in cancer treatment. Furthermore, it discusses the next-generation mTOR inhibitors and inhibition strategies created using nanoparticles. Since mTOR resistance mechanisms prevent the effects of mTOR inhibitors used in cancer treatments, new inhibition strategies should be developed. Inhibition approaches are created using nanoparticles, and one of them offers a promising treatment option with evidence supporting its effectiveness.

Species-specific Bioactivation of Morpholines as a Causative of Drug Induced Liver Injury Observed in Monkeys.

Everolimus, an allosteric mechanistic target of rapamycin (mTOR) inhibitor, recently demonstrated the therapeutic value of mTOR inhibitors for Central Nervous System (CNS) indications driven by hyperactivation of mTOR. A newer, potent brain-penetrant analog of everolimus, referred to as (1) in this manuscript [(S)-3-methyl-4-(7-((R)-3-methylmorpholino)-2- (thiazol-4-yl)-3H-imidazo[4,5-b]pyridin-5-yl)morpholine,(1)] catalytically inhibits mTOR function in the brain and increases the lifespan of mice with neuronal mTOR hyperactivation. Early evaluation of the safety of 1 was conducted in cynomolgus monkeys in which oral doses were administered to three animals in a rising-dose fashion (from 2 to 30 mg/kg/day). 1 produced severe toxicity including the evidence of hepatic toxicity, along with non-dose proportional increases in drug exposure. Investigations of cross-species hepatic bioactivation of 1 were conducted to assess whether the formation of reactive drug metabolites was associated with the mechanism of liver toxicity. 1 contained two morpholine rings known as structural alerts and can potentially form reactive intermediates through oxidative metabolism. Bioactivation of 1 was investigated in rat, human and monkey liver microsomes fortified with trapping agents such as methoxylamine or potassium cyanide. Our results suggest that bioactivation of the morpholine moieties to reactive intermediates may have been involved in the mechanism of liver toxicity observed with 1. Aldehyde intermediates trappable by methoxylamine were identified in rat and monkey liver microsomal studies. In addition, a total of four cyano conjugates arising from the formation of iminium ion intermediates were observed and identified. These findings may potentially explain the observed monkey toxicity. Interestingly, methoxylamine or cyano adducts of 1 were not observed in human liver microsomes. The bioactivation of 1 appears to be species-specific. Circumstantial evidence for the toxicity derived from 1 point to the formation of iminium ion intermediates trappable by cyanide in monkey liver microsomes. The cyano conjugates were only observed in monkey liver microsomes, potentially pointing to cause at least the hepatotoxicity observed in monkeys. In contrast, methoxylamine conjugates were detected in both rat and monkey liver microsomes, with only a trace amount in human liver microsomes. Cyano conjugates were not observed in human liver microsomes, challenging the team on the drugability and progressivity of 1 through drug development. The mechanisms for drug-induced liver toxicity are multifactorial. These results are highly suggestive that the iminium ion may be an important component in the mechanism of liver toxicity 1 observed in the monkey.

MTOR Regulates Mineralocorticoid Receptor Transcriptional Activity by ULK1-Dependent and -Independent Mechanisms.

The mineralocorticoid receptor (MR) is a transcription factor for genes mediating diverse, cell-specific functions, including trophic effects as well as promoting fluid/electrolyte homeostasis. It was reported that in intercalated cells, phosphorylation of the MR at serine 843 (S843) by Unc-51-like kinase (ULK1) inhibits MR activation and that phosphorylation of ULK1 by mechanistic target of rapamycin (mTOR) inactivates ULK1, and thereby prevents MR inactivation. We extended these findings with studies in M1 mouse cortical collecting duct cells stably expressing the rat MR and a reporter gene. Pharmacological inhibition of ULK1 dose-dependently increased ligand-induced MR transactivation, while ULK1 activation had no effect. Pharmacological inhibition of mTOR and CRISPR/gRNA gene knockdown of rapamycin-sensitive adapter protein of mTOR (Raptor) or rapamycin-insensitive companion of mTOR (Rictor) decreased phosphorylated ULK1 and ligand-induced activation of the MR reporter gene, as well as transcription of endogenous MR-target genes. As predicted, ULK1 inhibition had no effect on aldosterone-mediated transcription in M1 cells with the mutated MR-S843A (alanine cannot be phosphorylated). In contrast, mTOR inhibition dose-dependently decreased transcription in the MR-S843A cells, though not as completely as in cells with the wild-type MR-S843. mTOR, Raptor, and Rictor coprecipitated with the MR and addition of aldosterone increased their phosphorylated, active state. These results suggest that mTOR significantly regulates MR activity in at least 2 ways: by suppressing MR inactivation by ULK1, and by a yet ill-defined mechanism that involves direct association with MR. They also provide new insights into the diverse functions of ULK1 and mTOR, 2 key enzymes that monitor the cell's energy status.

MiR-769-3p inhibits cellular proliferation of KSHV-infected SH-SY5Y cells through targeting mTOR.

The infection by Kaposi's sarcoma-associated herpesvirus (KSHV) is one of the most common causes of death in AIDS patients. Our studies have found that KSHV can infect SH-SY5Y cells (named SK-RG) in vivo and mTOR was up-regulated, which results in remarkable enhancement of cell proliferation, migration. But the regulatory role of mTOR in KSHV infected neurons has not yet been fully elucidated. Here, we find that miR-769-3p is decreased in SK-RG cells, which can exert anti-KSHV effect through negatively regulating the expression of mTOR. The knockdown of mTOR or overexpress of miR-769-3p decreased the proliferation, migration ability and cell cycle related protein of SK-RG cells, and the expression of KSHV related genes. In contrast, activating mTOR function by 3BDO treatment weakened the cellular behaviors of miR-769-3p overexpressing cells. Meanwhile, overexpressed miR-769-3p and rapamycin showed a shared inhibition trend in the effects on cell proliferation and motility. Our data indicated that miR-769-3p can inhibit cell proliferation and migration by down regulating mTOR in KSHV infected SH-SY5Y cells, and can be a candidate molecule for anti-KSHV therapy.

Long and Short-Term Effect of mTOR Regulation on Cerebral Organoid Growth and Differentiations.

The mammalian target of rapamycin (mTOR) signaling is critical for the maintenance and differentiation of neurogenesis, and conceivably for many other brain developmental processes. However, in vivo studies of mTOR functions in the brain are often hampered due to the essential role of the associated signaling in brain development. We monitored the long- and short-term effects of mTOR signaling regulation on cerebral organoids growth, differentiation and function using an mTOR inhibitor (everolimus) and an mTOR activator (MHY1485). Short-term treatment with MHY1485 induced faster organoid growth and differentiation, while long-term treatment induced the maturation of cerebral organoids. These data suggest that the optimal activity of mTOR is crucial in maintaining normal brain development, and its role is not confined to the early neurogenic phase of brain development.

Pharmacological inhibition of S6K1 rescues synaptic deficits and attenuates seizures and depression in chronic epileptic rats.

Recent studies have shown that mTOR signaling plays an important role in synaptic plasticity. However, the function of S6K1, the mechanistic target of rapamycin kinase complex 1 (mTORC1) substrate, in epilepsy remains unknown. Our present study aimed to explore the mechanism by which S6K1 is involved in chronic epilepsy. First, immunostaining was used to measure neurite length and complexity in kainic acid (KA)-treated primary cultured neurons treated with PF-4708671, a highly selective S6K1 inhibitor. We obtained evidence for the role of S6K1 in protecting and promoting neuronal growth and development in vitro. Next, to explore the function and mechanism of the S6K1 inhibitor in epilepsy, a pilocarpine-induced chronic epileptic rat model was established. In vivo electrophysiology (including local field potentiation in CA1 and long-term potentiation), depression/anxiety-like behavior tests, and Golgi staining were performed to assess seizure behavior, power spectral density, depression/anxiety-like behavior, and synaptic plasticity. Furthermore, western blotting was applied to explore the potential molecular mechanisms. We found that inhibition of S6K1 expression significantly decreased seizures and depression-like behavior and restored power at low frequencies (1-80 Hz), especially in the delta, theta, and alpha bands, in chronic epileptic rats. In addition, PF-4708671 reversed the LTP defect in hippocampal CA3-CA1 and corrected spine loss and dendritic pathology. In conclusion, our data suggest that inhibition of S6K1 attenuates seizures and depression in chronic epileptic rats via the rescue of synaptic structural and functional deficits. Given the wide range of physiological functions of mTOR, inhibition of its effective but relatively simple functional downstream molecules is a promising target for the development of drugs for epilepsy.

The YAP-TEAD complex promotes senescent cell survival by lowering endoplasmic reticulum stress.

Sublethal cell damage can trigger senescence, a complex adaptive program characterized by growth arrest, resistance to apoptosis and a senescence-associated secretory phenotype (SASP). Here, a whole-genome CRISPR knockout screen revealed that proteins in the YAP-TEAD pathway influenced senescent cell viability. Accordingly, treating senescent cells with a drug that inhibited this pathway, verteporfin (VPF), selectively triggered apoptotic cell death largely by derepressing DDIT4, which in turn inhibited mTOR. Reducing mTOR function in senescent cells diminished endoplasmic reticulum (ER) biogenesis, triggering ER stress and apoptosis due to high demands on ER function by the SASP. Importantly, VPF treatment decreased the numbers of senescent cells in the organs of old mice and mice exhibiting doxorubicin-induced senescence. Moreover, VPF treatment reduced immune cell infiltration and pro-fibrotic transforming growth factor-β signaling in aging mouse lungs, improving tissue homeostasis. We present an alternative senolytic strategy that eliminates senescent cells by hindering ER activity required for SASP production.

Kinase-independent role of mTOR and on-/off-target effects of an mTOR kinase inhibitor.

mTOR, as a serine/threonine kinase, is a widely pursued anticancer target. Multiple clinical trials of mTOR kinase inhibitors are ongoing, but their specificity and safety features remain lacking. Here, we have employed an inducible kinase-inactive D2338A mTOR knock-in mouse model (mTOR-/KI) together with a mTOR conditional knockout model (mTOR-/-) to assess the kinase-dependent/-independent function of mTOR in hematopoiesis and the on-/off-target effects of mTOR kinase inhibitor AZD2014. Despite exhibiting many similar phenotypes to mTOR-/- mice in hematopoiesis, the mTOR-/KI mice survived longer and showed differences in hematopoietic progenitor cells compared to mTOR-/- mice, suggesting a kinase-independent function of mTOR in hematopoiesis. Gene expression signatures in hematopoietic stem cells (HSCs) further revealed both kinase-dependent and independent effects of mTOR. AZD2014, a lead mTOR kinase inhibitor, appeared to work mostly on-target in suppressing mTOR kinase activity, mimicking that of mTOR-/KI HSCs in transcriptome analysis, but it also induced a small set of off-target responses in mTOR-/KI HSCs. In murine and human myeloid leukemia, besides kinase-inhibitory on-target effects, AZD2014 displayed similar off-target and growth-inhibitory cytostatic effects. These studies provide new insights into kinase-dependent/-independent effects of mTOR in hematopoiesis and present a genetic means for precisely assessing the specificity of mTOR kinase inhibitors.

MTOR Plays a Conserved Role in Regulation of Nutritional Metabolism in Bivalve Sinonovacula constricta

The mammalian target of rapamycin (mTOR) has been shown to play a central role in regulating cell growth and metabolism. However, little is known about the function of mTOR in nutrient metabolism in bivalve mollusks. In this study, the role of mTOR in the regulation of nutrient metabolism was investigated in Sinonovacula constricta. First, the activation of mTOR was assayed after starvation and refeeding. Afterwards, the role of mTOR in the regulation of nutrient metabolism was investigated using an activator (MHY1485) or inhibitor (rapamycin) of mTOR. The open reading frame of the S. constricta mTOR is 7416 bp in length and encodes a polypeptide consisting of 2471 amino acids. The mTOR amino acid sequence of S. constricta was highly conserved when compared with other species and had a close evolutionary relationship with the TOR proteins of Crassostrea gigas and Lingula anatine. mTOR was expressed in the intestine, exhalent siphon, labial palppus, muscle, inhalent siphon, gill, mantle, digestive land, and gonad tissue of S. constricta, with the highest expression in muscle. During starvation, the level of phosphorylated mTOR protein was relatively low, and the ratio of LC3II/LC3I protein and the AMPKα mRNA level significantly increased with the increase in starvation time. After feeding, the level of phosphorylated mTOR protein increased from 0.13 to 0.56, and the ratio of LC3II/I protein and AMPKα mRNA level decreased from 1.17 to 0.38. MHY1485 significantly increased the level of phosphorylated 4E-BP1 and significantly decreased the ratio of LC3II/I proteins. Furthermore, MHY1485 significantly increased the mRNA level of the glucose metabolism-related gene glucokinase (GK), significantly decreased the mRNA expression of the G6P gene, and significantly increased the mRNA expression of the lipid synthesis-related genes sterol-regulatory element-binding protein (SREBP) and stearoyl-CoA desaturase (SCD). Rapamycin significantly reduced the level of phosphorylated 4E-BP1 and the mRNA expression of mTOR, and the expression level of phosphorylated 4EBP1 decreased from 0.97 to 0.28. Meanwhile, it also significantly reduced the mRNA expression of glucose metabolism-related genes GK, pyruvate kinase (PK), glucose transporter 1 (GLUT1), and G6P, as well as lipid synthesis-related genes SCD and acetyl-CoA carboxylase (ACC). These results indicate a conserved role of mTOR in regulating nutritional metabolism, including glucose metabolism, lipid synthesis, and autophagy in S. constricta.

Abstract 2706: Therapeutic silencing of Rictor using siRNA nanoparticles to selectively block mTORC2 signaling in triple negative breast cancer

Abstract Triple negative breast cancers (TNBCs) are aggressive malignancies with a high rate of recurrence even after neoadjuvant chemotherapy (NAC) and resection. Nearly 50% of NAC-treated TNBC patients harboring residual disease display mutations in the phosphatidyl inositol-3 kinase/mechanistic target of rapamycin (PI3K/mTOR) pathway, correlating PI3K/mTOR with chemoresistance. The protein kinase mTOR functions within two distinct protein complexes—mTORC1 and mTORC2. Inhibition of mTORC1 is ineffective in TNBCs. However, less is known regarding mTORC2 as a TNBC drug target, though mTORC2 is known to regulate tumor cell survival and motility/metastasis in other cancers. Here, we leverage siRNA technology to block expression of the mTORC2 obligate cofactor, Rictor, to test the hypothesis that selective mTORC2 inhibition will improve TNBC response to chemotherapy. siRNA-carrying nanoparticle complexes (si-NPs) continue to face systemic siRNA delivery challenges such as limited stability, off-target toxicities, and suboptimal tumor accumulation. Most conventional si-NPs are designed as “binary” systems comprising the siRNA cargo and the polymeric carrier that encapsulates it. Ternary si-NPs containing siRNA, an NP core-forming polymer (50B), and an NP surface-forming polymer (20kPEG-50B) have the potential to improve tumor silencing activity because of the participation of both polymers in siRNA encapsulation and endosome disruptive activity. Through concomitant structure-function optimization of 50B core polymer ratio (50B:20kPEG-50B) and molecular weight, we identified multiple lead ternary si-NPs with potent gene silencing activity, enhanced siRNA loading stability, and minimal toxicity. Following intravenous (i.v) treatment in vivo, all lead ternary si-NPs displayed increased circulation half-life, tumor uptake, and tumor gene silencing relative to the more canonical binary si-NPs. Critically, a single 1 mg/kg i.v. injection of our optimized formulation, 50B8-DP100 si-NPs, resulted in 80% tumor Rictor knockdown in orthotopic MDA-MB-231 tumors in mice. Therapeutic efficacy of 50B8-DP100 si-NPs, harboring siRNA against Rictor (siRictor-NPs) was then tested in models of TNBC. siRictor-NPs decreased cell growth and enhanced apoptosis in multiple TNBC cell lines. In an orthotopic HCC70 TNBC model, i.v. treatment with siRictor-NPs revealed substantial inhibition of mTORC2 activity in tumors by western analysis. siRictor-NP treatment also inhibited tumor growth to 52% relative to siControl-NP treatment. Preliminary in vitro studies further indicate that combining chemotherapy with siRictor-NPs improves TNBC cell killing over chemotherapy alone. Together, this work provides strong evidence for the therapeutic potential of Rictor knockdown and identifies a novel nanotechnology for the treatment of PI3K-active TNBC. Citation Format: Shrusti S. Patel, Ella N. Hoogenboezem, Fang Yu, Alex G. Sorets, Fiona K. Cherry, Justin H. Lo, Nora Francini, Richard A. d'Arcy, Rebecca S. Cook, Craig L. Duvall. Therapeutic silencing of Rictor using siRNA nanoparticles to selectively block mTORC2 signaling in triple negative breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2706.

Industrial pollutans and epigenetic factors associated with cardiomyopathies

The article presents a review of current scientific articles related to a few particular questions of molecular-genetic and epigenetic pathogenesis of some cardiomyopathy types that can be the object of interest assuming potential associations with pathophysiological mechanisms of pollutants and industrial toxins impaction. The possible benefits may arise from that kind of approach due to the fact that toxic agents in question are generally recognized at the moment as one of the cardiovascular disease onset and progression factors. The need for multidirectional theoretical developments targeting potential pharmacology methods aimed to at least partially eliminate such a challenge becomes more and more apparent. We focused on mTOR function chains, translation factor eIF4E and splicing regulator RBM20 interconnected with RAAS and T3 regulatory cascades. A part of our attention was also concentrated on cardiomyocytes methylome profiling in connection with pollutant toxicodynamics and cardiomyopathies pathogenesis.

Abstract P1-13-19: ESAM reduces anti-HER2 therapy sensitivity by activating mTOR pathway in HER2 positive breast cancer

Abstract Background: Trastuzumab combined with pertuzumab is the main therapy for HER2 positive breast cancer, but poor patient response due to drug resistance remains a clinical challenge. Organoids derived from tumor patients can highly maintain the heterogeneity of the original tumor, and have been used in drug sensitivity testing and new drug development. To screen for genes that associated with trastuzumab or pertuzumab drug resistance, this study used HER2-positive breast cancer organoids to establish a model of trastuzumab combined with pertuzumab and conducted high-throughput sequencing to screen the differential genes. We carried out further research to explore the effect of ESAM on drug sensitivity of HER2-targeted therapy and clarify the specific regulatory mechanisms and potential therapeutic targets of ESAM. Method: 8 HER2 positive breast cancer organoids were cultured. Immunohistochemistry, hematoxylin-eosin staining and Immunofluorescence were performed to identify the consistency between organoids and primitive tumors. According to drug sensitivity results of organoids to trastuzumab combined with pertuzumab, organoids were divided into a relatively sensitive group and a relatively insensitive group. Trastuzumab combined with pertuzumab was regularly used to stimulate the two groups. After 3 cycles, high-throughput transcriptome sequencing was used to evaluate their gene expression to find a gene responsible for trastuzumab and pertuzumab resistance. METABRIC and our center database were used to determine the prognostic value of ESAM. ESAM overexpression and knockdown stably transfected cell lines were constructed in SK-BR-3 and BT474 breast cancer cell lines by lentivirus. Colony formation assay, CCK-8 assay, organoid model and mouse xenograft model were conducted to examine the influence of ESAM on proliferation and trastuzumab or pertuzumab sensitization in vitro and in vivo. RNA-seq and GSEA analysis were performed to investigate the downstream pathways of ESAM. Western blot was used to confirm the relationship between ESAM and mTOR pathway. Small interfering RNA and mTOR/PI3K pathway inhibitors were used to confirm the function of mTOR in ESAM-induced drug resistance of trastuzumab. Results: HER2 positive breast cancer organoids can maintain the pathological characteristics of primitive tumors. The results of high-throughput transcriptome show that ESAM is significantly up-regulated in the relatively insensitive group compared to the relatively sensitive group. METABRIC and our center database suggest that high ESAM mRNA expression was associated with poor OS, RFS, DFS and PFS of HER2-positive breast cancer patients. CCK-8 and cell colony formation assay confirm that ESAM can promote the proliferation of HER2-positive breast cancer cells and inhibit the drug sensitivity of HER2-positive breast cancer cells to trastuzumab and pertuzumab. GSEA analysis shows high ESAM can activate mTORC1 signaling pathway. Western blotting analysis proves the expression of ESAM is positively correlated with mTOR pathway. Inhibition of mTOR pathway in ESAM overexpression cells can suppress ESAM-mediated proliferation and reverse the drug sensitivity of cells to trastuzumab and pertuzumab. In vivo, overexpression of ESAM can promote the proliferation of mouse mammary tumors and reduce the sensitivity of mouse mammary tumors to trastuzumab, combined use of PI3K inhibitor could reverse drug sensitivity of mouse mammary tumors to trastuzumab. Conclusion: High ESAM expression is associated with poor prognosis in patients with HER2 positive breast cancer. ESAM can activate mTOR pathway, promote cell proliferation and reduce the sensitivity of HER2 positive breast cancer cells to trastuzumab and pertuzumab, which can be inhibited by the application of PI3K/mTOR inhibitors. Keywords: ESAM; HER2 positive breast cancer; HER2 targeted therapy; mTOR; drug sensitivity. Citation Format: Jiong Wu, Xujie Zhou, Yayun Chi, Jingyan Xue. ESAM reduces anti-HER2 therapy sensitivity by activating mTOR pathway in HER2 positive breast cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P1-13-19.

The roles and mechanisms of circular RNAs related to mTOR in cancers.

Circular RNAs (circRNAs) are stable molecules with covalently closed structures that have an irreplaceable role in the occurrence, progression, and even treatment of plenty of cancers. Mammalian/mechanistic target of rapamycin (mTOR) is a key regulator in cancers and plays several biological functions, such as proliferation, migration, invasion, autophagy, and apoptosis. All data were collected through PubMed and CNKI, using terms including "circRNA," "mTOR," "caner," "signaling pathway," "biomarker," "diagnosis," "treatment." Articles published in Chinese and English were included. In this review, the expression, function, and mechanism of circRNA-associated mTOR in cancers were described. CircRNA-associated-mTOR can regulate the progression and therapy of a variety of cancers in multiple signaling pathways, such as phosphatidylinositol-3-kinase (PI3K)/protein kinase B (Akt)/mTOR, mitogen-activated protein kinase (MAPK)/mTOR, and AMP-activated protein kinase (AMPK)/mTOR axis. These cancers including esophageal carcinoma (circLPAR3, ciRS-7), gastric cancer (circNRIP1, hsa_circ_0010882, hsa_circ_0000117, hsa_circ_0072309, and circST3GAL6), colorectal cancer (hsa_circ_0000392, hsa_circ_0084927, hsa_circ_0104631, and circFBXW7), liver cancer (circC16orf62, hsa_circ_100338, hsa_circ_0004001, hsa_circ_0004123, hsa_circ_0075792, hsa_circ_0079299, and hsa_circ_0002130), pancreatic cancer (circ-IARS and circRHOBTB3), renal carcinoma (ciRS-7), bladder cancer (circUBE2K), prostate cancer (circMBOAT2 and circ-ITCH), ovarian cancer (circEEF2, circRAB11FIP1, circMYLK, and circTPCN), endometrial cancer (hsa_circ_0002577 and circWHSC1), lung cancer (circHIPK3, hsa_circ_0001666), thyroid cancer (hsa_circ_0007694 and hsa_circ_0008274), glioma (circGFRA1, circ-MAPK4, circPCMTD1, and hsa_circ_0037251), osteosarcoma (circTCF25), leukemia (circ-PRKDC), and breast cancer (hsa_circ_0000199, circUBAP2, and circWHSC1).

High Glucose-Induced Cardiomyocyte Damage Involves Interplay between Endothelin ET-1/ETA/ETB Receptor and mTOR Pathway.

Patients with type two diabetes mellitus (T2DM) are at increased risk for cardiovascular diseases. Impairments of endothelin-1 (ET-1) signaling and mTOR pathway have been implicated in diabetic cardiomyopathies. However, the molecular interplay between the ET-1 and mTOR pathway under high glucose (HG) conditions in H9c2 cardiomyoblasts has not been investigated. We employed MTT assay, qPCR, western blotting, fluorescence assays, and confocal microscopy to assess the oxidative stress and mitochondrial damage under hyperglycemic conditions in H9c2 cells. Our results showed that HG-induced cellular stress leads to a significant decline in cell survival and an impairment in the activation of ETA-R/ETB-R and the mTOR main components, Raptor and Rictor. These changes induced by HG were accompanied by a reactive oxygen species (ROS) level increase and mitochondrial membrane potential (MMP) loss. In addition, the fragmentation of mitochondria and a decrease in mitochondrial size were observed. However, the inhibition of either ETA-R alone by ambrisentan or ETA-R/ETB-R by bosentan or the partial blockage of the mTOR function by silencing Raptor or Rictor counteracted those adverse effects on the cellular function. Altogether, our findings prove that ET-1 signaling under HG conditions leads to a significant mitochondrial dysfunction involving contributions from the mTOR pathway.

The regulation of skin homeostasis, repair and the pathogenesis of skin diseases by spatiotemporal activation of epidermal mTOR signaling.

The epidermis, the outmost layer of the skin, is a stratified squamous epithelium that protects the body from the external world. The epidermis and its appendages need constantly renew themselves and replace the damaged tissues caused by environmental assaults. The mechanistic target of rapamycin (mTOR) signaling is a central controller of cell growth and metabolism that plays a critical role in development, homeostasis and diseases. Recent findings suggest that mTOR signaling is activated in a spatiotemporal and context-dependent manner in the epidermis, coordinating diverse skin homeostatic processes. Dysregulation of mTOR signaling underlies the pathogenesis of skin diseases, including psoriasis and skin cancer. In this review, we discuss the role of epidermal mTOR signaling activity and function in skin, with a focus on skin barrier formation, hair regeneration, wound repair, as well as skin pathological disorders. We propose that fine-tuned control of mTOR signaling is essential for epidermal structural and functional integrity.

Dapagliflozin as an autophagic enhancer via LKB1/AMPK/SIRT1 pathway in ovariectomized/d-galactose Alzheimer’s rat model

Autophagy and mitochondrial deficits are characteristics of early phase of Alzheimer’s disease (AD). Sodium-glucose cotransporter-2 inhibitors have been nominated as a promising class against AD hallmarks. However, there are no available data yet to discuss the impact of gliflozins on autophagic pathways in AD. Peripherally, dapagliflozin’s (DAPA) effect is mostly owed to autophagic signals. Thus, the goal of this study is to screen the power of DAPA centrally on LKB1/AMPK/SIRT1/mTOR signaling in the ovariectomized/d-galactose (OVX/d-Gal) rat model. Animals were arbitrarily distributed between 5 groups; the first group undergone sham operation, while remaining groups undergone OVX followed by d-Gal (150 mg/kg/day; i.p.) for 70 days. After 6 weeks, the third, fourth, and fifth groups received DAPA (1 mg/kg/day; p.o.); concomitantly with the AMPK inhibitor dorsomorphin (DORSO, 25 µg/rat, i.v.) in the fourth group and the SIRT1 inhibitor EX-527 (10 µg/rat, i.v.) in the fifth group. DAPA mitigated cognitive deficits of OVX/d-Gal rats, as mirrored in neurobehavioral task with hippocampal histopathological examination and immunohistochemical aggregates of p-Tau. The neuroprotective effect of DAPA was manifested by elevation of energy sensors; AMP/ATP ratio and LKB1/AMPK protein expressions along with autophagic markers; SIRT1, Beclin1, and LC3B expressions. Downstream the latter, DAPA boosted mTOR and mitochondrial function; TFAM, in contrary lessened BACE1. Herein, DORSO or EX-527 co-administration prohibited DAPA’s actions where DORSO elucidated DAPA’s direct effect on LKB1 while EX-527 mirrored its indirect effect on SIRT1. Therefore, DAPA implied its anti-AD effect, at least in part, via boosting hippocampal LKB1/AMPK/SIRT1/mTOR signaling in OVX/d-Gal rat model.Graphical abstract