bims-tubesc 2021-11-28 papers

bims-tubesc

Biomed News

on Molecular mechanisms in tuberous sclerosis

Issue of 2021–11–28
twelve papers selected by

Massive renal angiomyolipomas in tuberous sclerosis complex.
Benign tumors in TSC are amenable to treatment by GD3 CAR T cells in mice.
Neurosurgical Considerations of Neurocutaneous Syndromes.
Development of a versatile HPLC-based method to evaluate the activation status of small GTPases.
Tumor Syndromes: Neurosurgical Evaluation and Management.
Clinical and pathological features of renal epithelioid angiomyolipoma (PEComa): A single institution series.
Oncocytic renal neoplasms with diffuse keratin 7 immunohistochemistry harbor frequent alterations in the mammalian target of rapamycin pathway.
mTOR pathway: A potential therapeutic target for spinal cord injury.
GPR43 Suppresses Intestinal Tumor Growth by Modification of the Mammalian Target of Rapamycin Complex 1 Activity in ApcMin/+ Mice.
The fission yeast FLCN/FNIP complex augments TORC1 repression or activation in response to amino acid (AA) availability.
Monomethyl branched-chain fatty acid mediates amino acid sensing upstream of mTORC1.
Mechanistic Target of Rapamycin Complex 2 Regulation of the Primary Human Trophoblast Cell Transcriptome.

Kidney Int. 2021 Dec;pii: S0085-2538(21)00428-2. [Epub ahead of print]100(6): 1354

Massive renal angiomyolipomas in tuberous sclerosis complex.

Grace Y Chong, Maroun T Chedid, Theodora A Potretzke, Fouad T Chebib.

DOI: https://doi.org/10.1016/j.kint.2021.03.037
JCI Insight. 2021 Nov 22. pii: e152014. [Epub ahead of print]6(22):

Benign tumors in TSC are amenable to treatment by GD3 CAR T cells in mice.

Ancy Thomas, Saurav Sumughan, Emilia R Dellacecca, Rohan S Shivde, Nicola Lancki, Zhussipbek Mukhatayev, Cristina C Vaca, Fei Han, Levi Barse, Steven W Henning, Jesus Zamora-Pineda, Suhail Akhtar, Nikhilesh Gupta, Jasmine O Zahid, Stephanie R Zack, Prathyaya Ramesh, Dinesh Jaishankar, Agnes Sy Lo, Joel Moss, Maria M Picken, Thomas N Darling, Denise M Scholtens, Daniel F Dilling, Richard P Junghans, I Caroline Le Poole.

  Mutations underlying disease in tuberous sclerosis complex (TSC) give rise to tumors with biallelic mutations in TSC1 or TSC2 and hyperactive mammalian target of rapamycin complex 1 (mTORC1). Benign tumors might exhibit de novo expression of immunogens, targetable by immunotherapy. As tumors may rely on ganglioside D3 (GD3) expression for mTORC1 activation and growth, we compared GD3 expression in tissues from patients with TSC and controls. GD3 was overexpressed in affected tissues from patients with TSC and also in aging Tsc2+/- mice. As GD3 overexpression was not accompanied by marked natural immune responses to the target molecule, we performed preclinical studies with GD3 chimeric antigen receptor (CAR) T cells. Polyfunctional CAR T cells were cytotoxic toward GD3-overexpressing targets. In mice challenged with Tsc2-/- tumor cells, CAR T cells substantially and durably reduced the tumor burden, correlating with increased T cell infiltration. We also treated aged Tsc2+/- heterozygous (>60 weeks) mice that carry spontaneous Tsc2-/- tumors with GD3 CAR or untransduced T cells and evaluated them at endpoint. Following CAR T cell treatment, the majority of mice were tumor free while all control animals carried tumors. The outcomes demonstrate a strong treatment effect and suggest that targeting GD3 can be successful in TSC.

Keywords:  Antigen; Immunology; Immunotherapy; T cells; Therapeutics

DOI:  https://doi.org/10.1172/jci.insight.152014
Neurosurg Clin N Am. 2022 Jan;pii: S1042-3680(21)00090-5. [Epub ahead of print]33(1): 81-89

Neurosurgical Considerations of Neurocutaneous Syndromes.

Rajiv R Iyer, Jennifer M Strahle, Mari L Groves.

  The phakomatoses are a group of genetic and acquired disorders characterized by neurologic, cutaneous, and often ocular manifestations, thus commonly referred to as neurocutaneous syndromes. In several of these conditions the underlying genetic pathophysiology has been elucidated, which will continue to play an important role in advancing therapeutic techniques. This article focuses on several examples of such neurocutaneous syndromes, with special attention to the relevant neurosurgical considerations of these patients.

Keywords:  Epilepsy; Gorlin syndrome; Hereditary hemorrhagic telangiectasia; Neurocutaneous syndrome; Sturge-Weber syndrome; Tuberous sclerosis complex; subependymal giant cell astrocytoma

DOI:  https://doi.org/10.1016/j.nec.2021.09.013
J Biol Chem. 2021 Nov 18. pii: S0021-9258(21)01237-0. [Epub ahead of print] 101428

Development of a versatile HPLC-based method to evaluate the activation status of small GTPases.

Makoto Araki, Kaho Yoshimoto, Meguri Ohta, Toshiaki Katada, Kenji Kontani.

  Small GTPases cycle between an inactive GDP-bound and an active GTP-bound state to control various cellular events, such as cell proliferation, cytoskeleton organization, and membrane trafficking. Clarifying the guanine nucleotide-bound states of small GTPases is vital for understanding the regulation of small GTPase functions and the subsequent cellular responses. Although several methods have been developed to analyze small GTPase activities, our knowledge of the activities for many small GTPases is limited, partly because of the lack of versatile methods to estimate small GTPase activity without unique probes and specialized equipment. In the present study, we developed a versatile and straightforward HPLC-based assay to analyze the activation status of small GTPases by directly quantifying the amounts of guanine nucleotides bound to them. This assay was validated by analyzing the RAS-subfamily GTPases, including HRAS, which showed that the ratios of GTP-bound forms were comparable to those obtained in previous studies. Furthermore, we applied this assay to the investigation of psychiatric disorder-associated mutations of RHEB (RHEB/P37L and RHEB/S68P), revealing that both mutations cause an increase in the ratio of the GTP-bound form in cells. Mechanistically, loss of sensitivity to TSC2 (a GTPase-activating protein for RHEB) for RHEB/P37L, as well as both decreased sensitivity to TSC2 and accelerated guanine-nucleotide exchange for RHEB/S68P, are involved in the increase of their GTP-bound forms, respectively. In summary, the HPLC-based assay developed in this study provides a valuable tool for analyzing small GTPases for which the activities and regulatory mechanisms are less well understood.

Keywords:  GTPase-activating protein; RHEB; Ras protein; high-performance liquid chromatography; mammalian target of rapamycin; signal transduction; small GTPase; tuberous sclerosis complex

DOI:  https://doi.org/10.1016/j.jbc.2021.101428
Neurosurg Clin N Am. 2022 Jan;pii: S1042-3680(21)00082-6. [Epub ahead of print]33(1): 91-104

Tumor Syndromes: Neurosurgical Evaluation and Management.

Aravinda Ganapathy, Elizabeth Juarez Diaz, Justin T Coleman, Kimberly A Mackey.

  There are multiple syndromes associated with tumors of the central nervous system (CNS). The most common CNS tumor syndrome is neurofibromatosis-1, with well-defined major and minor criteria needed for diagnosis. Other syndromes with variable degree of CNS and extra-CNS involvement that the neurosurgeon should be aware of include neurofibromatosis-2; Turcot syndrome; Cowden syndrome; Gorlin syndrome; Li-Fraumeni syndrome; ataxia-telangiectasia; multiple endocrine neoplasia type 1; von Hippel-Lindau syndrome; and tuberous sclerosis complex. Although most CNS tumor syndromes follow an autosomal dominant pattern of inheritance, the genetic underpinnings of each disease are complex and increasingly better understood.

Keywords:  Cowden syndrome; Gorlin syndrome; Li-Fraumeni syndrome; Neurofibromatosis; Tuberous sclerosis complex; Tumor syndrome; Turcot syndrome; von Hippel-Lindau syndrome

DOI:  https://doi.org/10.1016/j.nec.2021.09.007
Urol Oncol. 2021 Nov 20. pii: S1078-1439(21)00435-X. [Epub ahead of print]

Clinical and pathological features of renal epithelioid angiomyolipoma (PEComa): A single institution series.

Ragheed Saoud, Tanya W Kristof, Clark Judge, Vaibhav Chumbalkar, Tatjana Antic, Scott Eggener, Parth Modi.

  Renal angiomyolipomas are benign tumors of the kidney that belong to the 'PEComa: perivascular epithelioid cell' family. Epithelioid AMLs (eAML) are a rare monotypic subtype with malignant potential, that can occur sporadically or be associated with tuberous sclerosis (TSC). Due to their epithelioid nature, eAMLs can closely resemble high-grade renal cell carcinoma (RCC), which may result in misdiagnosis. Multiple clinicopathologic parameters are predictive of worse outcomes for patients with eAML. Those can be used to stratify patients into groups with low, intermediate and high risk for disease progression. A high index of suspicion and a thorough immunohistochemical study are required to correctly diagnose eAML. Radiographically, eAMLs are also a diagnostic challenge as they share features with RCC on CT and MR imaging. Due to this close mimicry, the true incidence of eAML is thought to be much higher than 200 cases as reported in the literature. We report a series of four patients diagnosed with eAML and compare their clinical courses. We also report on the successful treatment of a patient with pulmonary metastasis from eAML using the mTOR inhibitor, everolimus. By identifying eAML and recognizing its high-risk features, it is possible mTOR inhibitors may have a meaningful role in the adjuvant treatment of these patients.

Keywords:  Angiomyolipoma; Epithelioid; Tuberous sclerosis; mTOR inhibitor

DOI:  https://doi.org/10.1016/j.urolonc.2021.09.010
Mod Pathol. 2021 Nov 20.

Oncocytic renal neoplasms with diffuse keratin 7 immunohistochemistry harbor frequent alterations in the mammalian target of rapamycin pathway.

Sambit K Mohanty, Abhishek Satapathy, Aditi Aggarwal, Sourav K Mishra, Nakul Y Sampat, Shivani Sharma, Sean R Williamson.

Low-grade oncocytic tumor (LOT) has been recently proposed as a unique renal tumor. However, we have encountered tumors with more oncocytoma-like morphology that show diffuse keratin 7 reactivity, which we sought to characterize molecularly. Eighteen tumors with a diffuse keratin 7 positive and KIT negative pattern were identified from 184 with predominantly oncocytoma-like histology. These tumors were subjected to detailed immunohistochemical evaluation and 14 were evaluated using the Illumina® HiSeq 4000 platform for 324 cancer-associated genes. Patients' ages ranged from 39 to 80 (median = 59.5 years) with a male to female ratio of 1.25:1. Morphology was predominantly oncocytoma-like with discrete nests, compared to the solid and edematous patterns described in LOT. Other than positive keratin 7 and negative KIT, the tumor cells were positive for PAX8, E-cadherin, AE1/AE3, Ber-EP4, AMACR, CD10, and MOC31, and were negative for other studied markers. FH and INI1 were normal. Eleven of 14 harbored genomic abnormalities, likely sporadic, primarily involving the MTOR pathway (73%). Overall, the alterations included MTOR activating mutation (n = 1), TSC1 inactivating mutation (n = 1), TSC2 mutation (p.X534 splice site, n = 1), STK11 (a negative regulator of the MTOR pathway) mutation (n = 1), both STK11 and TSC1 mutations (n = 1), biallelic loss of PTEN and TSC1 deletion (n = 1), and MET amplification and TSC1 inactivating mutation (n = 1). Amplification of FGFR3 was identified in one additional tumor. Other alterations included FOXP1 loss (n = 1), NF2 E427 homozygous loss (n = 1), and PI3KCA activating mutation (n = 1). At a median follow-up of 68 months (2-147 months) for 15 patients, all were alive without disease. Oncocytic renal tumors with diffuse keratin 7 labeling show frequent alterations in the TSC/MTOR pathway, despite more oncocytoma-like morphology than initially described in LOT, likely expanding the morphologic spectrum of the latter.

DOI: https://doi.org/10.1038/s41379-021-00969-6
Biomed Pharmacother. 2021 Nov 17. pii: S0753-3322(21)01216-6. [Epub ahead of print]145 112430

mTOR pathway: A potential therapeutic target for spinal cord injury.

Yi Ding, Qin Chen.

  Spinal cord injury (SCI) is the most common disabling spinal injury, and the complex pathological process can eventually lead to severe neurological dysfunction. Many studies have reported that the mammalian target of rapamycin (mTOR) signaling pathway plays an important role in synaptogenesis, neuron growth, differentiation, and survival after central nervous system injury. It is also involved in various traumatic and central nervous system diseases, including traumatic brain injury, neonatal hypoxic-ischemic brain injury, Alzheimer's disease, Parkinson's disease, and cerebral apoplexy. mTOR has also been reported to play an important regulatory role in various pathophysiological processes following SCI. Activation of mTOR signals after SCI can regulate physiological and pathological processes, such as proliferation and differentiation of neural stem cells, regeneration of nerve axons, neuroinflammation, and glial scar formation, through various pathways. Inhibition of mTOR activity has been confirmed to promote repair in SCI. At present, many studies have reported that Chinese herbal medicine can inhibit the SCI-activated mTOR pathway to improve the microenvironment and promote nerve repair after SCI. Due to the role of the mTOR pathway in SCI, it may be a potential therapeutic target for SCI. This review is focused on the pathophysiological process of SCI, characteristics of the mTOR pathway, role of the mTOR pathway in SCI, role of inhibition of mTOR on SCI, and role and significance of inhibition of mTOR by related Chinese herbal medicine inhibitors in SCI. In addition, the review discusses the deficiencies and solutions to mTOR and SCI research shortcomings. This study hopes to provide reference for mTOR and SCI research and a theoretical basis for SCI biotherapy.

Keywords:  Glial scar; Nerve recovery; Spinal cord injury (SCI); Therapeutic targets; mTOR pathway

DOI:  https://doi.org/10.1016/j.biopha.2021.112430
Med Princ Pract. 2021 Oct 01.

GPR43 Suppresses Intestinal Tumor Growth by Modification of the Mammalian Target of Rapamycin Complex 1 Activity in ApcMin/+ Mice.

Lingling Kong, Namiko Hoshi, Yunlong Sui, Yasutaka Yamada, Ryutaro Yoshida, Makoto Ooi, Zibin Tian, Ikuo Kimura, Yuzo Kodama.

   OBJECTIVE: G protein-coupled receptor 43 (GPR43), a receptor for short-chain fatty acids, plays a role in suppressing tumor growth; however, the detailed underlying mechanism needs to be comprehensively elucidated. In this study, we investigated the role of GPR43 in inhibiting tumor growth using ApcMin/+, a murine model of intestinal tumors.
MATERIALS AND METHODS: Using GPR43-/- ApcMin/+ and GPR43+/- ApcMin/+ mice, the number of tumors was analyzed at the end of the experimental period. Immunohistochemistry, quantitative polymerase chain reaction, and Western blotting were performed to analyze cellular proliferation and proliferation-associated signal pathways.
RESULTS: Our results revealed that GPR43 deficiency resulted in increased tumor numbers in ApcMin/+ mice. Ki67 was highly expressed in GPR43-/- mice (p > 0.05). Increased expression levels of proinflammatory cytokines, including interleukin-6 and tumor necrosis factor-α, and amino acid transporters were not observed in GPR43-deficient mice compared to GPR43-sufficient mice. Furthermore, GPR43-deficient tumor tissues showed enhanced mammalian target of rapamycin-mediated phosphorylated ribosomal protein S6 kinase beta-1 (p > 0.05) and phosphorylated eukaryotic translation initiation factor 4E-binding protein 1 (p > 0.05), but not Akt (protein kinase B) phosphorylation (p = 0.7088).
CONCLUSION: Collectively, GPR43 affords protection against tumor growth at least partly through inhibition of the mammalian target of rapamycin complex 1 pathway.

Keywords:  Colon cancer; FFAR2; G protein-coupled receptor 43; Mammalian target of rapamycin; Short-chain fatty acids

DOI:  https://doi.org/10.1159/000518621
iScience. 2021 Nov 19. 24(11): 103338

The fission yeast FLCN/FNIP complex augments TORC1 repression or activation in response to amino acid (AA) availability.

Isabel A Calvo, Shalini Sharma, Joao A Paulo, Alexander O D Gulka, Andras Boeszoermenyi, Jingyu Zhang, Jose M Lombana, Christina M Palmieri, Laura A Laviolette, Haribabu Arthanari, Othon Iliopoulos, Steven P Gygi, Mo Motamedi.

  The target of Rapamycin complex1 (TORC1) senses and integrates several environmental signals, including amino acid (AA) availability, to regulate cell growth. Folliculin (FLCN) is a tumor suppressor (TS) protein in renal cell carcinoma, which paradoxically activates TORC1 in response to AA supplementation. Few tractable systems for modeling FLCN as a TS are available. Here, we characterize the FLCN-containing complex in Schizosaccharomyces pombe (called BFC) and show that BFC augments TORC1 repression and activation in response to AA starvation and supplementation, respectively. BFC co-immunoprecipitates V-ATPase, a TORC1 modulator, and regulates its activity in an AA-dependent manner. BFC genetic and proteomic networks identify the conserved peptide transmembrane transporter Ptr2 and the phosphoribosylformylglycinamidine synthase Ade3 as new AA-dependent regulators of TORC1. Overall, these data ascribe an additional repressive function to Folliculin in TORC1 regulation and reveal S. pombe as an excellent system for modeling the AA-dependent, FLCN-mediated repression of TORC1 in eukaryotes.

Keywords:  Cell biology; Cellular physiology; Functional aspects of cell biology

DOI:  https://doi.org/10.1016/j.isci.2021.103338
Dev Cell. 2021 Nov 22. pii: S1534-5807(21)00890-X. [Epub ahead of print]56(22): 3171

Monomethyl branched-chain fatty acid mediates amino acid sensing upstream of mTORC1.

Mengnan Zhu, Fukang Teng, Na Li, Li Zhang, Shuxian Zhang, Fan Xu, Jing Shao, Haipeng Sun, Huanhu Zhu.

DOI: https://doi.org/10.1016/j.devcel.2021.11.005
Front Cell Dev Biol. 2021 ;9 670980

Mechanistic Target of Rapamycin Complex 2 Regulation of the Primary Human Trophoblast Cell Transcriptome.

Fredrick J Rosario, Amy Catherine Kelly, Madhulika B Gupta, Theresa L Powell, Laura Cox, Thomas Jansson.

  Mechanistic Target of Rapamycin Complex 2 (mTORC2) regulates placental amino acid and folate transport. However, the role of mTORC2 in modulating other placental functions is largely unexplored. We used a gene array following the silencing of rictor to identify genes regulated by mTORC2 in primary human trophoblast (PHT) cells. Four hundred and nine genes were differentially expressed; 102 genes were down-regulated and 307 up-regulated. Pathway analyses demonstrated that inhibition of mTORC2 resulted in increased expression of genes encoding for pro-inflammatory IL-6, VEGF-A, leptin, and inflammatory signaling (SAPK/JNK). Furthermore, down-regulated genes were functionally enriched in genes involved in angiogenesis (Osteopontin) and multivitamin transport (SLC5A6). In addition, the protein expression of leptin, VEGFA, IL-6 was increased and negatively correlated to mTORC2 signaling in human placentas collected from pregnancies complicated by intrauterine growth restriction (IUGR). In contrast, the protein expression of Osteopontin and SLC5A6 was decreased and positively correlated to mTORC2 signaling in human IUGR placentas. In conclusion, mTORC2 signaling regulates trophoblast expression of genes involved in inflammation, micronutrient transport, and angiogenesis, representing novel links between mTOR signaling and multiple placental functions necessary for fetal growth and development.

Keywords:  gene array; human; maternal-fetal exchange; nutrient sensor; placenta

DOI:  https://doi.org/10.3389/fcell.2021.670980