KPTN-related disorder is an autosomal recessive disorder associated with germline variants in KPTN (previously known as kaptin), a component of the mTOR regulatory complex KICSTOR. To gain further... Show moreKPTN-related disorder is an autosomal recessive disorder associated with germline variants in KPTN (previously known as kaptin), a component of the mTOR regulatory complex KICSTOR. To gain further insights into the pathogenesis of KPTN-related disorder, we analysed mouse knockout and human stem cell KPTN loss-of-function models.Kptn−/− mice display many of the key KPTN-related disorder phenotypes, including brain overgrowth, behavioural abnormalities, and cognitive deficits. By assessment of affected individuals, we have identified widespread cognitive deficits (n = 6) and postnatal onset of brain overgrowth (n = 19). By analysing head size data from their parents (n = 24), we have identified a previously unrecognized KPTN dosage-sensitivity, resulting in increased head circumference in heterozygous carriers of pathogenic KPTN variants.Molecular and structural analysis of Kptn−/− mice revealed pathological changes, including differences in brain size, shape and cell numbers primarily due to abnormal postnatal brain development. Both the mouse and differentiated induced pluripotent stem cell models of the disorder display transcriptional and biochemical evidence for altered mTOR pathway signalling, supporting the role of KPTN in regulating mTORC1.By treatment in our KPTN mouse model, we found that the increased mTOR signalling downstream of KPTN is rapamycin sensitive, highlighting possible therapeutic avenues with currently available mTOR inhibitors. These findings place KPTN-related disorder in the broader group of mTORC1-related disorders affecting brain structure, cognitive function and network integrity. Show less
Wind, S.S.; Jansen, M.A.A.; Rijsbergen, M.; Esdonk, M.J. van; Ziagkos, D.; Cheng, W.C.; ... ; Rissmann, R. 2022
Simple Summary Primary cutaneous T-cell lymphomas (CTCLs) are a group of lymphomas that present in the skin without extracutaneous localizations at diagnosis. Recent studies in clinical and... Show moreSimple Summary Primary cutaneous T-cell lymphomas (CTCLs) are a group of lymphomas that present in the skin without extracutaneous localizations at diagnosis. Recent studies in clinical and translational research augmented our understanding of the pathogenesis and pathophysiology of different subtypes of CTCL, enabling the identification of novel therapeutic drug targets. In this study, the primary focus is on bimiralisib gel 2%, a dual pan-class PI3K/mTOR inhibitor, and its potential to inhibit the PI3K/AKT/mTOR signaling pathway as a novel therapeutic target in CTCL. Mycosis fungoides (MF) is a subtype of CTCL with a low incidence and high medical need for novel treatments. The objective of this randomized, placebo-controlled, double-blinded, first-in-human study was to evaluate safety, efficacy, cutaneous and systemic pharmacokinetics (PK) of topical bimiralisib in healthy volunteers (HVs) and MF patients. In this trial, a total of 6 HVs and 19 early-stage MF patients were treated with 2.0% bimiralisib gel and/or placebo. Drug efficacy was assessed by the Composite Assessment of Index Lesion Severity (CAILS) score, supported by objective measuring methods to quantify lesion severity. PK blood samples were collected frequently and cutaneous PK was investigated in skin punch biopsies on the last day of treatment. Local distribution of bimiralisib in HVs showed a mean exposure of 2.54 mu g/g in the epidermis. A systemic concentration was observed after application of a target dose of 2 mg/cm(2) on 400 cm(2), with a mean C-avg of 0.96 ng/mL. Systemic exposure of bimiralisib was reached in all treated MF patients, and normalized plasma concentrations showed a 144% increased exposure compared to HVs, with an observed mean C-avg of 4.49 ng/mL and a mean cutaneous concentration of 5.3 mu g/g. No difference in CAILS or objective lesion severity quantification upon 42 days of once-daily treatment was observed in the MF patient group. In general, the treatment was well tolerated in terms of local reactions as well as systemic adverse events. In conclusion, we showed that topical bimiralisib treatment leads to (i) meaningful cutaneous drug levels and (ii) well-tolerated systemic drug exposure in MF patients and (iii) a lack of clinical efficacy, in need of further exploration due to numerous unknown factors, before depreciation of topical bimiralisib as a novel therapeutic drug for CTCLs. Show less
Invasive lobular carcinoma (ILC) is the second most common type of breast cancer. Hallmarks of ILC include disruption of adherens junctions and hyperactivation of phosphoinositide 3-kinase (PI3K)... Show moreInvasive lobular carcinoma (ILC) is the second most common type of breast cancer. Hallmarks of ILC include disruption of adherens junctions and hyperactivation of phosphoinositide 3-kinase (PI3K)-mTOR signaling. The tumor suppressor PTEN regulates PI3K signaling. We present a preclinical mouse model of ILC metastasis, based on inactivation of the adherens junction protein E-cadherin and the tumor suppressor p53 and surgical excision of primary tumors. In this model, pharmacological mTOR inhibition blocks growth of primary tumors as well as metastatic disease, and this response is partially dependent on the adaptive immune system. Loss of E-cadherin mouse mammary epithelium leads to apoptosis, and PTEN activation alone results in squamous metaplastic mammary tumors, but a combination of these events leads to ILC formation, indicating a causal role of PI3K signaling together with E-cadherin loss in ILC. Combined somatic loss of the adherens junction molecule p120 and p53 in the mouse mammary gland leads to metaplastic mammary tumors, and loss of p120 in breast cancer cell lines promotes anoikis resistance through hypersensitization of growth factor receptor (GFR) signaling. Combined inactivation of E-cadherin, p120 and p53 induces basal-like tumors, with an epithelial-to- mesenchymal-transition (EMT) phenotype, and no ILC formation. Show less
Uil, M.; Hau, C.M.; Ahdi, M.; Mills, J.D.; Kers, J.; Saleem, M.A.; ... ; Roelofs, J.J.T.H. 2021
Background. Diabetic nephropathy (DN) is a major complication of diabetes and the main cause of end-stage renal disease. Extracellular vesicles (EVs) are small cell-derived vesicles that can alter... Show moreBackground. Diabetic nephropathy (DN) is a major complication of diabetes and the main cause of end-stage renal disease. Extracellular vesicles (EVs) are small cell-derived vesicles that can alter disease progression by microRNA (miRNA) transfer.Methods. In this study, we aimed to characterize the cellular origin and miRNA content of EVs in plasma samples of type 2 diabetes patients at various stages of DN. Type 2 diabetes patients were classified in three groups: normoalbuminuria, microalbuminuria and macroalbuminuria. The concentration and cellular origin of plasma EVs were measured by flow cytometry. A total of 752 EV miRNAs were profiled in 18 subjects and differentially expressed miRNAs were validated.Results. Diabetic patients with microalbuminuria and/or macroalbuminuria showed elevated concentrations of total EVs and EVs from endothelial cells, platelets, leucocytes and erythrocytes compared with diabetic controls. miR-99a-5p was upregulated in macroalbuminuric patients compared with normoalbuminuric and microalbuminuric patients. Transfection of miR-99a-5p in cultured human podocytes downregulated mammalian target of rapamycin (mTOR) protein expression and downregulated the podocyte injury marker vimentin.Conclusions. Type 2 diabetes patients with microalbuminuria and macroalbuminuria display differential EV profiles. miR-99a-5p expression is elevated in EVs from macroalbuminuria and mTOR is its validated mRNA target. Show less
Myeloid cells, including macrophages and dendritic cells, represent an important first line of defense against infections. Upon recognition of pathogens, these cells undergo a metabolic... Show moreMyeloid cells, including macrophages and dendritic cells, represent an important first line of defense against infections. Upon recognition of pathogens, these cells undergo a metabolic reprogramming that supports their activation and ability to respond to the invading pathogens. An important metabolic regulator of these cells is mammalian target of rapamycin (mTOR). During infection, pathogens use host metabolic pathways to scavenge host nutrients, as well as target metabolic pathways for subversion of the host immune response that together facilitate pathogen survival. Given the pivotal role of mTOR in controlling metabolism and DC and macrophage function, pathogens have evolved strategies to target this pathway to manipulate these cells. This review seeks to discuss the most recent insights into how pathogens target DC and macrophage metabolism to subvert potential deleterious immune responses against them, by focusing on the metabolic pathways that are known to regulate and to be regulated by mTOR signaling including amino acid, lipid and carbohydrate metabolism, and autophagy. Show less
Klarenbeek, S.; Doornebal, C.W.; Kas, S.M.; Bonzanni, N.; Bhin, J.; Braumuller, T.M.; ... ; Jonkers, J. 2020
Effective treatment of invasive lobular carcinoma (ILC) of the breast is hampered by late detection, invasive growth, distant metastasis, and poor response to chemotherapy. Phosphoinositide 3... Show moreEffective treatment of invasive lobular carcinoma (ILC) of the breast is hampered by late detection, invasive growth, distant metastasis, and poor response to chemotherapy. Phosphoinositide 3-kinase (PI3K) signaling, one of the major druggable oncogenic signaling networks, is frequently activated in ILC. We investigated treatment response and resistance to AZD8055, an inhibitor of mammalian target of rapamycin (mTOR), in the K14-cre;Cdh1(Flox/Flox);Trp53(Flox/Flox) (KEP) mouse model of metastatic ILC. Inhibition of mTOR signaling blocked the growth of primary KEP tumors as well as the progression of metastatic disease. However, primary tumors and distant metastases eventually acquired resistance after long-term AZD8055 treatment, despite continued effective suppression of mTOR signaling in cancer cells. Interestingly, therapeutic responses were associated with increased expression of genes related to antigen presentation. Consistent with this observation, increased numbers of tumor-infiltrating major histocompatibility complex class II-positive (MHCII+) immune cells were observed in treatment-responsive KEP tumors. Acquisition of treatment resistance was associated with loss of MHCII+ cells and reduced expression of genes related to the adaptive immune system. The therapeutic efficacy of mTOR inhibition was reduced in Rag1(-/-) mice lacking mature T and B lymphocytes, compared to immunocompetent mice. Furthermore, therapy responsiveness could be partially rescued by transplanting AZD8055-resistant KEP tumors into treatment-naive immunocompetent hosts. Collectively, these data indicate that the PI3K signaling pathway is an attractive therapeutic target in invasive lobular carcinoma, and that part of the therapeutic effect of mTOR inhibition is mediated by the adaptive immune system. Show less
The insulin receptor (INSR) and the insulin growth factor 1 receptor (IGF1R) play important roles in the etiology of both diabetes mellitus and breast cancer. We aimed to evaluate the expression of... Show moreThe insulin receptor (INSR) and the insulin growth factor 1 receptor (IGF1R) play important roles in the etiology of both diabetes mellitus and breast cancer. We aimed to evaluate the expression of hormone and insulin-related proteins within or related to the PI3K and MAPK pathway in breast tumors of women with or without diabetes mellitus, treated with or without insulin (analogues).\nImmunohistochemistry was performed on tumor tissue of 312 women with invasive breast cancer, with or without pre-existing diabetes mellitus, diagnosed in 2000-2010, who were randomly selected from a Danish breast cancer cohort. Women with diabetes were 2:1 frequency matched by year of birth and age at breast cancer diagnosis to those without diabetes. Tumor Microarrays were successfully stained for p-ER, EGFR, p-ERK1/2, p-mTOR, and IGF1R, and scored by a breast pathologist. Associations of expression of these proteins with diabetes, insulin treatment (human insulin and insulin analogues) and other diabetes medication were evaluated by multivariable logistic regression adjusting for menopause and BMI; effect modification by menopausal status, BMI, and ER status was assessed using interactions terms.\nWe found no significant differences in expression of any of the proteins in breast tumors of women with (n = 211) and without diabetes (n = 101). Among women with diabetes, insulin use (n = 53) was significantly associated with higher tumor protein expression of IGF1R (OR = 2.36; 95%CI:1.02-5.52; p = 0.04) and p-mTOR (OR = 2.35; 95%CI:1.13-4.88; p = 0.02), especially among women treated with insulin analogues. Menopause seemed to modified the association between insulin and IGF1R expression (p = 0.07); the difference in IGF1R expression was only observed in tumors of premenopausal women (OR = 5.10; 95%CI:1.36-19.14; p = 0.02). We found no associations between other types of diabetes medication, such as metformin, and protein expression of the five proteins evaluated.\nIn our study, breast tumors of women with pre-existing diabetes did not show an altered expression of selected PI3K/MAPK pathway-related proteins. We observed an association between insulin treatment and increased p-mTOR and IGF1R expression of breast tumors, especially in premenopausal women. This observation, if confirmed, might be clinically relevant since the use of IGF1R and mTOR inhibitors are currently investigated in clinical trials. Show less
Lachmandas, E.; Beigier-Bompadre, M.; Cheng, S.C.; Kumar, V.; Laarhoven, A. van; Wang, X.H.; ... ; Netea, M.G. 2016
During this research we wanted to gain more insight into the potential gene repertoire that is involved in the hippocampus when coping with stress and regulating learning and memory... Show more During this research we wanted to gain more insight into the potential gene repertoire that is involved in the hippocampus when coping with stress and regulating learning and memory processes. To investigate this further we aimed to answer the question:""What are the primary genomic binding sites of the by stress and thus cortisol stimulated protein receptors MR and GR in the hippocampus?" To answer this question, new methods have been applied to determine where exactly MR and GR bind to the DNA, to find out which genes are potentially involved during stress management. As a result we have identified thousands of GR-binding sites at the DNA of which we have analyzed a selection in further detail. One of the identified pathways that have been found to be sensitive for activated GR and corticosteroids is the mTOR pathway. This pathway is involved in neuronal plasticity, which is the fundament for resilience. We have found that expression of the mTOR protein is decreased after exposure to acute stress when the organism has a history of chronic stress. Our results indicate that the reduced resilience after experiencing chronic stress is likely to be mediated by mTOR. Show less
People of South Asian origin have an increased risk of developing type 2 diabetes (T2D) and cardiovascular disease (CVD) compared to people of Western European descent. Not only is the prevalence... Show morePeople of South Asian origin have an increased risk of developing type 2 diabetes (T2D) and cardiovascular disease (CVD) compared to people of Western European descent. Not only is the prevalence of these diseases higher in South Asians, they also occur at a younger age and lower BMI, and have a more severe course. The high prevalence of T2D and CVD in South Asians, who comprise one fifth of the total world__s population, poses a major health and socioeconomic burden worldwide. The underlying cause of this excess risk is, however, still poorly understood. The studies described in this thesis were performed to gain more insight in the pathogenesis of T2D and CVD in South Asians and to provide new leads for preventive strategies and treatment options. For this purpose sophisticated techniques were used such as hyperinsulinemic-euglycemic clamp with stable isotopes, indirect calorimetry, skeletal muscle biopsies, MRI and spectroscopy, and brown fat quantification using PET-CT-imaging, combined with short-term dietary interventions, in healthy lean young adult men and overweight adult men. These studies have led to a number of promising areas for further research. It seems that not one, but multiple metabolic mechanisms have been affected, most likely due to gene-environment interactions. Show less
