Genetic and epigenetic inactivation of SESTRIN1 controls mTORC1 and response to EZH2 inhibition in follicular lymphoma

Follicular lymphoma regulatory T-cell origin and function

Introduction

Follicular Lymphoma (FL) results from the malignant transformation of germinal center (GC) B cells. FL B cells display recurrent and diverse genetic alterations, some of them favoring their direct interaction with their cell microenvironment, including follicular helper T cells (Tfh). Although FL-Tfh key role is well-documented, the impact of their regulatory counterpart, the follicular regulatory T cell (Tfr) compartment, is still sparse.

Methods

The aim of this study was to characterize FL-Tfr phenotype by cytometry, gene expression profile, FL-Tfr origin by transcriptomic analysis, and functionality by in vitro assays.

Results

CD4+CXCR5+CD25hiICOS+ FL-Tfr displayed a regulatory program that is close to classical regulatory T cell (Treg) program, at the transcriptomic and methylome levels. Accordingly, Tfr imprinting stigmata were found on FL-Tfh and FL-B cells, compared to their physiological counterparts. In addition, FL-Tfr co-culture with autologous FL-Tfh or cytotoxic FL-CD8+ T cells inhibited their proliferation in vitro. Finally, although FL-Tfr shared many characteristics with Treg, TCR sequencing analyses demonstrated that part of them derived from precursors shared with FL-Tfh.

Discussion

Altogether, these findings uncover the role and origin of a Tfr subset in FL niche and may be useful for lymphomagenesis knowledge and therapeutic management.

The fifth edition of the WHO classification of mature B-cell neoplasms: open questions for research

The fifth edition of the World Health Organization Classification of Haematolymphoid Tumours (WHO-HAEM5) is the product of an evidence-based evolution of the revised fourth edition with wide multidisciplinary consultation. Nonetheless, while every classification incorporates scientific advances and aims to improve upon the prior version, medical knowledge remains incomplete and individual neoplasms may not be easily subclassified in a given scheme. Thus, optimal classification requires ongoing study, and there are certain aspects of some entities and subtypes that require further refinements. In this review, we highlight a selection of these challenging areas to prompt more research investigations. These include (1) a 'placeholder term' of splenic B-cell lymphoma/leukaemia with prominent nucleoli (SBLPN) to accommodate many of the splenic lymphomas previously classified as hairy cell leukaemia variant and B-prolymphocytic leukaemia, a clear new start to define their pathobiology; (2) how best to classify BCL2 rearrangement negative follicular lymphoma including those with BCL6 rearrangement, integrating the emerging new knowledge on various germinal centre B-cell subsets; (3) what is the spectrum of non-IG gene partners of MYC translocation in diffuse large B-cell lymphoma/high-grade B-cell lymphoma and how they impact MYC expression and clinical outcome; how best to investigate this in a routine clinical setting; and (4) how best to define high-grade B-cell lymphoma not otherwise specified and high-grade B-cell lymphoma with 11q aberrations to distinguish them from their mimics and characterise their molecular pathogenetic mechanism. Addressing these questions would provide more robust evidence to better define these entities/subtypes, improve their diagnosis and/or prognostic stratification, leading to better patient care. © 2024 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

EZH2 as a potential therapeutic target for gastrointestinal cancers

Gastrointestinal (GI) cancers continue to be a major cause of mortality and morbidity globally. Understanding the molecular pathways associated with cancer progression and severity is essential for creating effective cancer treatments. In cancer research, there is a notable emphasis on Enhancer of zeste homolog 2 (EZH2), a key player in gene expression influenced by its irregular expression and capacity to attach to promoters and alter methylation status. This review explores the impact of EZH2 signaling on various GI cancers, such as colorectal, gastric, pancreatic, hepatocellular, esophageal, and cholangiocarcinoma. The primary function of EZH2 signaling is to facilitate the accelerated progression of cancer cells. Additionally, EZH2 has the capacity to modulate the reaction of GI cancers to chemotherapy and radiotherapy. Numerous pathways, including long non-coding RNAs and microRNAs, serve as upstream regulators of EZH2 in these types of cancer. EZH2's enzymatic activity enables it to attach to target gene promoters, resulting in methylation that modifies their expression. EZH2 could be considered as an independent prognostic factor, with increased expression correlating with a worse disease prognosis. Additionally, a range of gene therapies including small interfering RNA, and anti-tumor agents are being explored to target EZH2 for cancer treatment. This comprehensive review underscores the current insights into EZH2 signaling in gastrointestinal cancers and examines the prospect of therapies targeting EZH2 to enhance patient outcomes.

Modeling the crosstalk between malignant B cells and their microenvironment in B-cell lymphomas: challenges and opportunities

B-cell lymphomas are a group of heterogeneous neoplasms resulting from the clonal expansion of mature B cells arrested at various stages of differentiation. Specifically, two lymphoma subtypes arise from germinal centers (GCs), namely follicular lymphoma (FL) and GC B-cell diffuse large B-cell lymphoma (GCB-DLBCL). In addition to recent advances in describing the genetic landscape of FL and GCB-DLBCL, tumor microenvironment (TME) has progressively emerged as a central determinant of early lymphomagenesis, subclonal evolution, and late progression/transformation. The lymphoma-supportive niche integrates a dynamic and coordinated network of immune and stromal cells defining microarchitecture and mechanical constraints and regulating tumor cell migration, survival, proliferation, and immune escape. Several questions are still unsolved regarding the interplay between lymphoma B cells and their TME, including the mechanisms supporting these bidirectional interactions, the impact of the kinetic and spatial heterogeneity of the tumor niche on B-cell heterogeneity, and how individual genetic alterations can trigger both B-cell intrinsic and B-cell extrinsic signals driving the reprogramming of non-malignant cells. Finally, it is not clear whether these interactions might promote resistance to treatment or, conversely, offer valuable therapeutic opportunities. A major challenge in addressing these questions is the lack of relevant models integrating tumor cells with specific genetic hits, non-malignant cells with adequate functional properties and organization, extracellular matrix, and biomechanical forces. We propose here an overview of the 3D in vitro models, xenograft approaches, and genetically-engineered mouse models recently developed to study GC B-cell lymphomas with a specific focus on the pros and cons of each strategy in understanding B-cell lymphomagenesis and evaluating new therapeutic strategies.

The clinical and molecular taxonomy of t(14;18)-negative follicular lymphomas

Follicular lymphoma (FL) is a neoplasm derived from germinal center B cells, composed of centrocytes and centroblasts, with at least a focal follicular growth pattern. The t(14;18) translocation together with epigenetic deregulation through recurrent genetic alterations are now recognized as the hallmark of FL. Nevertheless, FL is a heterogeneous disease, clinically, morphologically, and biologically. The existence of FL lacking the t(14;18) chromosomal alteration highlights the complex pathogenesis of FL, and indicates that there are alternative pathogenetic mechanisms that can induce a neoplasm with follicular center B-cell phenotype. Based on their clinical presentation, t(14;18)-negative FLs can be divided into 3 broad groups: nodal presentation, extranodal presentation, and those affecting predominantly children and young adults. Recent studies have shed some light into the genetic alterations of t(14;18)-negative FL. Within the group of t(14;18)-negative FL with nodal presentation, cases with STAT6 mutations are increasingly recognized as a distinctive molecular subgroup, often cooccurring with CREBBP and/or TNFRSF14 mutations. FL with BCL6 rearrangement shows clinicopathological similarities to its t(14;18)-positive counterpart. In contrast, t(14;18)-negative FL in extranodal sites is characterized mainly by TNFRSF14 mutations in the absence of chromatin modifying gene mutations. FL in children have a unique molecular landscape when compared with those in adults. Pediatric-type FL (PTFL) is characterized by MAP2K1, TNFRSF14, and/or IRF8 mutations, whereas large B-cell lymphoma with IRF4 rearrangement is now recognized as a distinct entity, different from PTFL. Ultimately, a better understanding of FL biology and heterogeneity should help to understand the clinical differences and help guide patient management and treatment decisions.

Context-defined cancer co-dependency mapping identifies a functional interplay between PRC2 and MLL-MEN1 complex in lymphoma

Interplay between chromatin-associated complexes and modifications critically contribute to the partitioning of epigenome into stable and functionally distinct domains. Yet there is a lack of systematic identification of chromatin crosstalk mechanisms, limiting our understanding of the dynamic transition between chromatin states during development and disease. Here we perform co-dependency mapping of genes using CRISPR-Cas9-mediated fitness screens in pan-cancer cell lines to quantify gene-gene functional relationships. We identify 145 co-dependency modules and further define the molecular context underlying the essentiality of these modules by incorporating mutational, epigenome, gene expression and drug sensitivity profiles of cell lines. These analyses assign new protein complex composition and function, and predict new functional interactions, including an unexpected co-dependency between two transcriptionally counteracting chromatin complexes - polycomb repressive complex 2 (PRC2) and MLL-MEN1 complex. We show that PRC2-mediated H3K27 tri-methylation regulates the genome-wide distribution of MLL1 and MEN1. In lymphoma cells with EZH2 gain-of-function mutations, the re-localization of MLL-MEN1 complex drives oncogenic gene expression and results in a hypersensitivity to pharmacologic inhibition of MEN1. Together, our findings provide a resource for discovery of trans-regulatory interactions as mechanisms of chromatin regulation and potential targets of synthetic lethality.

Disruption to the FOXO-PRDM1 axis resulting from deletions of chromosome 6 in acute lymphoblastic leukaemia

A common problem in the study of human malignancy is the elucidation of cancer driver mechanisms associated with recurrent deletion of regions containing multiple genes. Taking B-cell acute lymphoblastic leukaemia (B-ALL) and large deletions of 6q [del(6q)] as a model, we integrated analysis of functional cDNA clone tracking assays with patient genomic and transcriptomic data, to identify the transcription factors FOXO3 and PRDM1 as candidate tumour suppressor genes (TSG). Analysis of cell cycle and transcriptomic changes following overexpression of FOXO3 or PRDM1 indicated that they co-operate to promote cell cycle exit at the pre-B cell stage. FOXO1 abnormalities are absent in B-ALL, but like FOXO3, FOXO1 expression suppressed growth of TCF3::PBX1 and ETV6::RUNX1 B-ALL in-vitro. While both FOXOs induced PRDM1 and other genes contributing to late pre-B cell development, FOXO1 alone induced the key transcription factor, IRF4, and chemokine, CXCR4. CRISPR-Cas9 screening identified FOXO3 as a TSG, while FOXO1 emerged as essential for B-ALL growth. We relate this FOXO3-specific leukaemia-protective role to suppression of glycolysis based on integrated analysis of CRISPR-data and gene sets induced or suppressed by FOXO1 and FOXO3. Pan-FOXO agonist Selinexor induced the glycolysis inhibitor TXNIP and suppressed B-ALL growth at low dose (ID50 < 50 nM).

Biology of follicular lymphoma: insights and windows of clinical opportunity

Follicular lymphoma (FL) is a heterogeneous disease, both clinically and biologically. The biological behavior and development of FL is a culmination of complex multistep processes underpinned by genetic and nongenetic determinants. Epigenetic deregulation through recurrent genetic alterations is now a recognized major biological hallmark of FL, alongside the t(14;18) translocation. In parallel, there is a strong interplay between the lymphoma B cells and the immune microenvironment, with the microenvironment serving as a critical enabler by creating a tumor-supportive niche and modulating the immune response to favor survival of the malignant B cells. A further layer of complexity arises from the biological heterogeneity that occurs between patients and within an individual, both over the course of the disease and at different sites of disease involvement. Altogether, taking the first steps to bridge the understanding of these various biological components and how to evaluate these clinically may aid and inform future strategies, including logical therapeutic interventions, risk stratification, therapy selection, and disease monitoring.

Diversity of Circulating NKT Cells in Defense against Carbapenem-Resistant Klebsiella Pneumoniae Infection

Nosocomial infection caused by carbapenem-resistant Klebsiella pneumonia (CRKP) infection has become a global public health problem. Human NK and NKT cells in peripheral immune responses are recognized as occupying a critical role in anti-bacterial immunity. Through performed scRNA-seq on serial peripheral blood samples from 3 patients with CRKP undergoing colonization, infection, and recovery conditions, we were able to described the immune responses of NK and NKT cells during CRKP infection and identified a mechanism that could contribute to CRKP clearance. The central player of CRKP infection process appears to be the NKT subset and CD56hiNKT subset which maintained immune competence during CRKP colonization. With time, CRKP leads to the loss of NK and CD160hiNKT cells in peripheral blood, resulting in suppressed immune responses and increased susceptibility to opportunistic infection. In summary, our study identified a possible mechanism for the CRKP invasion and to decipher the clues behind the host immune response that influences CRKP infection pathogenesis.

Molecular Cytogenetic Profiling Reveals Similarities and Differences Between Localized Nodal and Systemic Follicular Lymphomas

Recently, we have developed novel highly promising gene expression (GE) classifiers discriminating localized nodal (LFL) from systemic follicular lymphoma (SFL) with prognostic impact. However, few data are available in LFL especially concerning hotspot genetic alterations that are associated with the pathogenesis and prognosis of SFL. A total of 144 LFL and 527 SFL, enrolled in prospective clinical trials of the German Low Grade Lymphoma Study Group, were analyzed by fluorescence in situ hybridization to detect deletions in chromosomes 1p, 6q, and 17p as well as BCL2 translocations to determine their impact on clinical outcome of LFL patients. The frequency of chromosomal deletions in 1p and 17p was comparable between LFL and SFL, while 6q deletions and BCL2 translocations more frequently occurred in SFL. A higher proportion of 1p deletions was seen in BCL2-translocation–positive LFL, compared with BCL2-translocation–negative LFL. Deletions in chromosomes 1p, 6q, and 17p predicted clinical outcome of patients with SFL in the entire cohort, while only deletions in chromosome 1p retained its negative prognostic impact in R-CHOP–treated SFL. In contrast, no deletions in one of the investigated genetic loci predicted clinical outcome in LFL. Likewise, the presence or absence of BCL2 translocations had no prognostic impact in LFL. Despite representing a genetic portfolio closely resembling SFL, LFL showed some differences in deletion frequencies. BCL2 translocation and 6q deletion frequency differs between LFL and SFL and might contribute to distinct genetic profiles in LFL and SFL.

Follicular lymphoma-associated mutations in the V-ATPase chaperone VMA21 activate autophagy creating a targetable dependency

The discovery of recurrent mutations in subunits and regulators of the vacuolar-type H⁺-translocating ATPase (V-ATPase) in follicular lymphoma (FL) highlights a role for macroautophagy/autophagy, amino-acid, and nutrient-sensing pathways in the pathogenesis of this disease. Here, we report on novel mutations in the ER-resident chaperone VMA21, which is involved in V-ATPase assembly in 12% of FL. Mutations in a novel VMA21 hotspot (p.93X) result in the removal of a C-terminal non-canonical ER retrieval signal thus causing VMA21 mislocalization to lysosomes. The resulting impairment in V-ATPase activity prevents full lysosomal acidification and function, including impaired pH-dependent protein degradation as shown via lysosomal metabolomics and ultimately causes a degree of amino acid depletion in the cytoplasm. These deficiencies result in compensatory autophagy activation, as measured using multiple complementary assays in human and yeast cells. Of translational significance, the compensatory activation of autophagy creates a dependency for survival for VMA21-mutated primary human FL as shown using inhibitors to ULK1, the proximal autophagy-regulating kinase. Using high-throughput microscopy-based screening assays for autophagy-inhibiting compounds, we identify multiple clinical grade cyclin-dependent kinase inhibitors as promising drugs and thus provide new rationale for innovative clinical trials in FL harboring aberrant V-ATPase.Abbreviations: ALs: autolysosomes; APs: autophagosomes; ER: endoplasmic reticulum; FL: follicular lymphoma; GFP: green fluorescent protein; IP: immunoprecipitation; LE/LY: late endosomes/lysosomes; Lyso-IP: lysosomal immunoprecipitation; OST: oligosaccharide transferase; prApe1: precursor aminopeptidase I; SEP: super ecliptic pHluorin; V-ATPase: vacuolar-type H⁺-translocating ATPase.

Occupational lead exposure on genome-wide DNA methylation and DNA damage

Lead (Pb) exposure can induce DNA damage and alter DNA methylation but their inter-relationships have not been adequately determined. Our overall aims were to explore such relationships and to evaluate underlying epigenetic mechanisms of Pb-induced genotoxicity in Chinese workers. Blood Pb levels (BLLs) were determined and used as individual's Pb-exposure dose and the Comet assay (i.e., % tail DNA) was conducted to evaluate DNA damage. In the screening assay, 850 K BeadChip sequencing was performed on peripheral blood from 10 controls (BLLs ≤100 μg/L) and 20 exposed workers (i.e., 10 DNA-damaged and 10 DNA-undamaged workers). Using the technique, differentially methylated positions (DMPs) between the controls and the exposed workers were identified. In addition, DMPs were identified between the DNA-undamaged and DNA-damaged workers (% tail DNA >2.14%). In our validation assay, methylation levels of four candidate genes were measured by pyrosequencing in an independent sample set (n = 305), including RRAGC (Ras related GTP binding C), USP1 (Ubiquitin specific protease 1), COPS7B (COP9 signalosome subunit 7 B) and CHEK1 (Checkpoint kinase 1). The result of comparisons between the controls and the Pb-exposed workers show that DMPs were significantly enriched in genes related to nerve conduction and cell cycle. Between DNA-damaged group and DNA-undamaged group, differentially methylated genes were enriched in the pathways related to cell cycle and DNA integrity checkpoints. Additionally, methylation levels of RRAGC and USP1 were negatively associated with BLLs (P < 0.05), and the former mediated 19.40% of the effect of Pb on the % tail DNA. These findings collectively indicated that Pb-induced DNA damage was closely related to methylation of genes in cell cycle regulation, and methylation levels of RRAGC were involved in Pb-induced genotoxicity.

SESN1, negatively regulated by miR-377-3p, suppresses invasive growth of head and neck squamous cell carcinoma by interaction with SMAD3

Sestrin 1 (SESN1) is a stress-inducible protein that suppresses tumors in numerous cancers. However, the function of SESN1 in head and neck squamous cell carcinoma (HNSCC) is not clear and needs to be elucidated. Here, SESN1 expression was downregulated in HNSCC tissues and cell lines, and low SESN1 expression was positively correlated with poor prognosis in patients with HNSCC. Moreover, SESN1 overexpression inhibited the proliferation, migration, and invasion of HSC-6 and CAL-33 cells. In addition, the binding relationship between miR-377-3p and SESN1 was confirmed using luciferase reporter and RNA immunoprecipitation assays. Downregulation of SESN1 expression was consistent with high levels of miR-377-3p in HNSCC tissues. Linear regression analysis of clinical HNSCC tissues revealed a negative correlation between miR-377-3p and SESN1 expression. Moreover, co-immunoprecipitation mass spectrometry analysis revealed that SESN1 interacted with SMAD3, and SMAD3 reversed the increased proliferation, migration, and invasion of HSC-6 and CAL-33 cells caused by SESN1 knockdown. In conclusion, these findings provide evidence that SESN1 functions as a tumor suppressor and reveal the miR-377-3p-SESN1-SMAD3 regulatory axis that contributes to proliferation, migration, and invasion in HNSCC development, which may represent an interventional target for HNSCC therapy.

Mechanisms of Polycomb group protein function in cancer

Cancer arises from a multitude of disorders resulting in loss of differentiation and a stem cell-like phenotype characterized by uncontrolled growth. Polycomb Group (PcG) proteins are members of multiprotein complexes that are highly conserved throughout evolution. Historically, they have been described as essential for maintaining epigenetic cellular memory by locking homeotic genes in a transcriptionally repressed state. What was initially thought to be a function restricted to a few target genes, subsequently turned out to be of much broader relevance, since the main role of PcG complexes is to ensure a dynamically choregraphed spatio-temporal regulation of their numerous target genes during development. Their ability to modify chromatin landscapes and refine the expression of master genes controlling major switches in cellular decisions under physiological conditions is often misregulated in tumors. Surprisingly, their functional implication in the initiation and progression of cancer may be either dependent on Polycomb complexes, or specific for a subunit that acts independently of other PcG members. In this review, we describe how misregulated Polycomb proteins play a pleiotropic role in cancer by altering a broad spectrum of biological processes such as the proliferation-differentiation balance, metabolism and the immune response, all of which are crucial in tumor progression. We also illustrate how interfering with PcG functions can provide a powerful strategy to counter tumor progression.

Pathogenesis of follicular lymphoma: genetics to the microenvironment to clinical translation

Follicular lymphoma (FL) represents a heterogeneous disease both clinically and biologically. The pathognomonic t(14;18) translocation can no longer be thought of as the primary genetic driver, with increasing recognition of the biological relevance of recurrent genetic alterations in epigenetic regulators that now feature as a pivotal hallmark of this lymphoma subtype. Furthermore, sequencing studies have provided a near complete catalogue of additional genetic aberrations. Longitudinal and spatial genetic studies add an additional layer to the biological heterogeneity, providing preliminary molecular insights into high-risk phenotypes such as early progressors and transformation, and also supporting evidence for the existence of persisting re-populating cells that act as lymphoma reservoirs and harbingers for FL recurrence. Simultaneously, understanding of the tumour microenvironmental cues promoting lymphomagenesis and disease progression continue to broaden. More recently, studies are beginning to unravel the convergence and co-operation between the genetics, epigenetics and microenvironment. There is a pressing need to marry biology with therapeutics, especially with the burgeoning treatment landscape in FL, to aid in optimising patient selection and guiding the 'right drug to the right patient'.

[Clinical characteristics of patients with multiple myeloma harboring 6q deletion]

Objective: To study the clinical and cytogenetic characteristics of patients with multiple myeloma harboring 6q deletion, with the aim to determine the impact of 6q deletion on survival. Methods: This study included the retrospective analysis of 382 newly diagnosed patients with multiple myeloma in our hospital from 2014 to 2017 and compared the clinical and cytogenetic characteristics between patients with and without 6q deletion. The log-rank test and the Cox proportional hazards regression model were used to analyze prognostic factors for progression-free survival (PFS) and overall survival (OS) . Results: Compared to those without 6q, the patients with 6q deletion were older (median age, 63 vs 58 years, P=0.039) , had higher incidence of t (4; 14) (30.4% vs 16.4% , P=0.020) , and higher proportion of complex karyotypes (22.2% vs 5.3% , P=0.001) . Univariate survival analysis using the log-rank test revealed that 6q deletion was associated with shorter PFS. However, by the Cox multivariate proportional hazards regression model, 6q deletion was not an independent prognostic factor and its effect on survival was affected by age, t (4; 14) , and other risk factors. Conclusions: 6q deletion was common in elderly patients with multiple myeloma and was often accompanied by t (4;14) and complex karyotypes. However, 6q deletion was not an independent prognostic factor for multiple myeloma.

Human B Lymphomas Reveal Their Secrets Through Genetic Mouse Models

Lymphomas are cancers deriving from lymphocytes, arising preferentially in secondary lymphoid organs, and represent the 6th cancer worldwide and the most frequent blood cancer. The majority of B cell Non-Hodgkin lymphomas (B-NHL) develop from germinal center (GC) experienced mature B cells. GCs are transient structures that form in lymphoid organs in response to antigen exposure of naive B cells, and where B cell receptor (BCR) affinity maturation occurs to promote B cell differentiation into memory B and plasma cells producing high-affinity antibodies. Genomic instability associated with the somatic hypermutation (SHM) and class-switch recombination (CSR) processes during GC transit enhance susceptibility to malignant transformation. Most B cell differentiation steps in the GC are at the origin of frequent B cell malignant entities, namely Follicular Lymphoma (FL) and GCB diffuse large B cell lymphomas (GCB-DLBCL). Over the past decade, large sequencing efforts have provided a great boost in the identification of candidate oncogenes and tumor suppressors involved in FL and DLBCL oncogenesis. Mouse models have been instrumental to accurately mimic in vivo lymphoma-specific mutations and interrogate their normal function in the GC context and their oncogenic function leading to lymphoma onset. The limited access of biopsies during the initiating steps of the disease, the cellular and (epi)genetic heterogeneity of individual tumors across and within patients linked to perturbed dynamics of GC ecosystems make the development of genetically engineered mouse models crucial to decipher lymphomagenesis and disease progression and eventually to test the effects of novel targeted therapies. In this review, we provide an overview of some of the important genetically engineered mouse models that have been developed to recapitulate lymphoma-associated (epi)genetic alterations of two frequent GC-derived lymphoma entities: FL and GCB-DLCBL and describe how those mouse models have improved our knowledge of the molecular processes supporting GC B cell transformation.

Attacking the PI3K/Akt/mTOR signaling pathway for targeted therapeutic treatment in human cancer

Cancer is the second leading cause of human death globally. PI3K/Akt/mTOR signaling is one of the most frequently dysregulated signaling pathways observed in cancer patients that plays crucial roles in promoting tumor initiation, progression and therapy responses. This is largely due to that PI3K/Akt/mTOR signaling is indispensable for many cellular biological processes, including cell growth, metastasis, survival, metabolism, and others. As such, small molecule inhibitors targeting major kinase components of the PI3K/Akt/mTOR signaling pathway have drawn extensive attention and been developed and evaluated in preclinical models and clinical trials. Targeting a single kinase component within this signaling usually causes growth arrest rather than apoptosis associated with toxicity-induced adverse effects in patients. Combination therapies including PI3K/Akt/mTOR inhibitors show improved patient response and clinical outcome, albeit developed resistance has been reported. In this review, we focus on revealing the mechanisms leading to the hyperactivation of PI3K/Akt/mTOR signaling in cancer and summarizing efforts for developing PI3K/Akt/mTOR inhibitors as either mono-therapy or combination therapy in different cancer settings. We hope that this review will facilitate further understanding of the regulatory mechanisms governing dysregulation of PI3K/Akt/mTOR oncogenic signaling in cancer and provide insights into possible future directions for targeted therapeutic regimen for cancer treatment, by developing new agents, drug delivery systems, or combination regimen to target the PI3K/Akt/mTOR signaling pathway. This information will also provide effective patient stratification strategy to improve the patient response and clinical outcome for cancer patients with deregulated PI3K/Akt/mTOR signaling.

The Role of mTOR Signaling as a Therapeutic Target in Cancer

The aim of this review was to summarize current available information about the role of phosphatidylinositol-3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) signaling in cancer as a potential target for new therapy options. The mTOR and PI3K/AKT/mTORC1 (mTOR complex 1) signaling are critical for the regulation of many fundamental cell processes including protein synthesis, cell growth, metabolism, survival, catabolism, and autophagy, and deregulated mTOR signaling is implicated in cancer, metabolic dysregulation, and the aging process. In this review, we summarize the information about the structure and function of the mTOR pathway and discuss the mechanisms of its deregulation in human cancers including genetic alterations of PI3K/AKT/mTOR pathway components. We also present recent data regarding the PI3K/AKT/mTOR inhibitors in clinical studies and the treatment of cancer, as well the attendant problems of resistance and adverse effects.

Sestrin family - the stem controlling healthy ageing

Sestrins are a family of stress-responsive antioxidant proteins responsible for regulation of cell viability and metabolism. The best known Sestrin targets are mTORC1 and mTORC2 kinases that control different cellular processes including growth, viability, autophagy, and mitochondrial metabolism. Inactivation of the single Sestrin gene in invertebrates has an adverse impact on their healthspan and longevity, whereas each of the three Sestrin genes in mammals and other vertebrate organisms has a different impact on maintenance of a particular tissue, affecting its stress tolerance, function and regenerative capability. As a result, Sestrins attenuate ageing and suppress development of many age-related diseases including myocardial infarction, muscle atrophy, diabetes, and immune dysfunction, but exacerbate development of chronic obstructive pulmonary disease. Moreover, Sestrins play opposite roles in carcinogenesis in different tissues. Stem cells support tissue remodelling that influences ageing, and Sestrins might suppress ageing and age-related pathologies through control of stem cell biology. In this review, we will discuss the potential link between Sestrins, stem cells, and ageing.

Follicular lymphoma genomics

Although outcomes for follicular lymphoma (FL) continue to improve, it remains incurable for the majority of patients. Through next generation sequencing (NGS) studies, we now recognize that the genomic landscape of FL is skewed toward highly recurrent mutations in genes that encode epigenetic regulators co-occurring with the pathognomonic t(14;18) translocation. Adopting these technologies to study longitudinal and spatially-derived lymphomas has provided unique insights into the tumoral heterogeneity, clonal evolution of the disease and supports the existence of a tumor-repopulating population, considered the Achilles' heel of this lymphoma. An in-depth understanding of the genomics and its contribution to the disease pathogenesis is identifying new biomarkers and therapeutic targets that can be translated into clinical practice and, in the not too distant future, enable us to start considering precision-based approaches to the management of FL.

Potential new therapy of Rapalink-1, a new generation mammalian target of rapamycin inhibitor, against sunitinib-resistant renal cell carcinoma

Sunitinib, a multitargeted receptor tyrosine kinase inhibitor including vascular endothelial growth factor, has been widely used as a first-line treatment against metastatic renal cell carcinoma (mRCC). However, mRCC often acquires resistance to sunitinib, rendering it difficult to treat with this agent. Recently, Rapalink-1, a drug that links rapamycin and the mTOR kinase inhibitor MLN0128, has been developed with excellent therapeutic effects against breast cancer cells carrying mTOR resistance mutations. The aim of the present study was to evaluate the in vitro and in vivo therapeutic efficacy of Rapalink-1 against renal cell carcinoma (RCC) compared to temsirolimus, which is commonly used as a small molecule inhibitor of mTOR and is a derivative of rapamycin. In comparison with temsirolimus, Rapalink-1 showed significantly greater effects against proliferation, migration, invasion and cFolony formation in sunitinib-naïve RCC cells. Inhibition was achieved through suppression of the phosphorylation of substrates in the mTOR signal pathway, such as p70S6K, eukaryotic translation initiation factor 4E-binding protein 1 (4EBP1) and AKT. In addition, Rapalink-1 had greater tumor suppressive effects than temsirolimus against the sunitinib-resistant 786-o cell line (SU-R 786-o), which we had previously established, as well as 3 additional SU-R cell lines established here. RNA sequencing showed that Rapalink-1 suppressed not only the mTOR signaling pathway but also a part of the MAPK signaling pathway, the ErbB signaling pathway and ABC transporters that were associated with resistance to several drugs. Our study suggests the possibility of a new treatment option for patients with RCC that is either sunitinib-sensitive or sunitinib-resistant.

Mitochondrial localization of SESN2

SESN2 is a member of the evolutionarily conserved sestrin protein family found in most of the Metazoa species. The SESN2 gene is transcriptionally activated by many stress factors, including metabolic derangements, reactive oxygen species (ROS), and DNA-damage. As a result, SESN2 controls ROS accumulation, metabolism, and cell viability. The best-known function of SESN2 is the inhibition of the mechanistic target of rapamycin complex 1 kinase (mTORC1) that plays a central role in support of cell growth and suppression of autophagy. SESN2 inhibits mTORC1 activity through interaction with the GATOR2 protein complex preventing an inhibitory effect of GATOR2 on the GATOR1 protein complex. GATOR1 stimulates GTPase activity of the RagA/B small GTPase, the component of RagA/B:RagC/D complex, preventing mTORC1 translocation to the lysosomes and its activation by the small GTPase Rheb. Despite the well-established role of SESN2 in mTORC1 inhibition, other SESN2 activities are not well-characterized. We recently showed that SESN2 could control mitochondrial function and cell death via mTORC1-independent mechanisms, and these activities might be explained by direct effects of SESN2 on mitochondria. In this work, we examined mitochondrial localization of SESN2 and demonstrated that SESN2 is located on mitochondria and can be directly involved in the regulation of mitochondrial functions.

Molecular pathogenesis of germinal center-derived B cell lymphomas

B cell lymphomas comprise a heterogeneous group of genetically, biologically, and clinically distinct neoplasms that, in most cases, originate from the clonal expansion of B cells in the germinal center (GC). In recent years, the advent of novel genomics technologies has revolutionized our understanding of the molecular pathogenesis of lymphoid malignancies as a multistep process that requires the progressive accumulation of multiple genetic and epigenetic alterations. A common theme that emerged from these studies is the ability of lymphoma cells to co-opt the same biological programs and signal transduction networks that operate during the normal GC reaction, and misuse them for their own survival advantage. This review summarizes recent progress in the understanding of the genetic and epigenetic mechanisms that drive the malignant transformation of GC B cells. These insights provide a conceptual framework for the identification of cellular pathways that may be explored for precision medicine approaches.

Follicular lymphoma

Follicular lymphoma (FL) is a systemic neoplasm of the lymphoid tissue displaying germinal centre (GC) B cell differentiation. FL represents ~5% of all haematological neoplasms and ~20-25% of all new non-Hodgkin lymphoma diagnoses in western countries. Tumorigenesis starts in precursor B cells and becomes full-blown tumour when the cells reach the GC maturation step. FL is preceded by an asymptomatic preclinical phase in which premalignant B cells carrying a t(14;18) chromosomal translocation accumulate additional genetic alterations, although not all of these cells progress to the tumour phase. FL is an indolent lymphoma with largely favourable outcomes, although a fraction of patients is at risk of disease progression and adverse outcomes. Outcomes for FL in the rituximab era are encouraging, with ~80% of patients having an overall survival of >10 years. Patients with relapsed FL have a wide range of treatment options, including several chemoimmunotherapy regimens, phosphoinositide 3-kinase inhibitors, and lenalidomide plus rituximab. Promising new treatment approaches include epigenetic therapeutics and immune approaches such as chimeric antigen receptor T cell therapy. The identification of patients at high risk who require alternative therapies to the current standard of care is a growing need that will help direct clinical trial research. This Primer discusses the epidemiology of FL, its molecular and cellular pathogenesis and its diagnosis, classification and treatment.

p53-inducible SESTRINs might play opposite roles in the regulation of early and late stages of lung carcinogenesis

SESTRINs (SESN1-3) are proteins encoded by an evolutionarily conserved gene family that plays an important role in the regulation of cell viability and metabolism in response to stress. Many of the effects of SESTRINs are mediated by negative and positive regulation of mechanistic target of rapamycin kinase complexes 1 and 2 (mTORC1 and mTORC2), respectively, that are often deregulated in human cancers where they support cell growth, proliferation, and cell viability. Besides their effects on regulation of mTORC1/2, SESTRINs also control the accumulation of reactive oxygen species, cell death, and mitophagy. SESN1 and SESN2 are transcriptional targets of tumor suppressor protein p53 and may mediate tumor suppressor activities of p53. Therefore, we conducted studies based on a mouse lung cancer model and human lung adenocarcinoma A549 cells to evaluate the potential impact of SESN1 and SESN2 on lung carcinogenesis. While we observed that expression of SESN1 and SESN2 is often decreased in human tumors, inactivation of Sesn2 in mice positively regulates tumor growth through a mechanism associated with activation of AKT, while knockout of Sesn1 has no additional impact on carcinogenesis in Sesn2-deficient mice. However, inactivation of SESN1 and/or SESN2 in A549 cells accelerates cell proliferation and imparts resistance to cell death in response to glucose starvation. We propose that despite their contribution to early tumor growth, SESTRINs might suppress late stages of carcinogenesis through inhibition of cell proliferation or activation of cell death in conditions of nutrient deficiency.

Targeting mTOR and Metabolism in Cancer: Lessons and Innovations

Cancer cells support their growth and proliferation by reprogramming their metabolism in order to gain access to nutrients. Despite the heterogeneity in genetic mutations that lead to tumorigenesis, a common alteration in tumors occurs in pathways that upregulate nutrient acquisition. A central signaling pathway that controls metabolic processes is the mTOR pathway. The elucidation of the regulation and functions of mTOR can be traced to the discovery of the natural compound, rapamycin. Studies using rapamycin have unraveled the role of mTOR in the control of cell growth and metabolism. By sensing the intracellular nutrient status, mTOR orchestrates metabolic reprogramming by controlling nutrient uptake and flux through various metabolic pathways. The central role of mTOR in metabolic rewiring makes it a promising target for cancer therapy. Numerous clinical trials are ongoing to evaluate the efficacy of mTOR inhibition for cancer treatment. Rapamycin analogs have been approved to treat specific types of cancer. Since rapamycin does not fully inhibit mTOR activity, new compounds have been engineered to inhibit the catalytic activity of mTOR to more potently block its functions. Despite highly promising pre-clinical studies, early clinical trial results of these second generation mTOR inhibitors revealed increased toxicity and modest antitumor activity. The plasticity of metabolic processes and seemingly enormous capacity of malignant cells to salvage nutrients through various mechanisms make cancer therapy extremely challenging. Therefore, identifying metabolic vulnerabilities in different types of tumors would present opportunities for rational therapeutic strategies. Understanding how the different sources of nutrients are metabolized not just by the growing tumor but also by other cells from the microenvironment, in particular, immune cells, will also facilitate the design of more sophisticated and effective therapeutic regimen. In this review, we discuss the functions of mTOR in cancer metabolism that have been illuminated from pre-clinical studies. We then review key findings from clinical trials that target mTOR and the lessons we have learned from both pre-clinical and clinical studies that could provide insights on innovative therapeutic strategies, including immunotherapy to target mTOR signaling and the metabolic network in cancer.

Sestrin2: Its Potential Role and Regulatory Mechanism in Host Immune Response in Diseases

Sestrin2 (SESN2), a highly evolutionarily conserved protein, is critically involved in cellular responses to various stresses. SESN2 has a protective effect on physiological and pathological states mainly via regulating oxidative stress, endoplasmic reticulum stress, autophagy, metabolism, and inflammation. In recent years, breakthrough investigations with regard to the regulation and signaling mechanisms of SESN2 have markedly deepened our understanding of its potential role as well as its significance in host response. However, the functions of SESN2 in the immune system and inflammation remain elusive. It has been documented that many immune cells positively express SESN2 and, in turn, that SESN2 might modulate cellular activities. This review incorporates recent progress and aims to provide novel insight into the protective role and regulatory pathway of SESN2, which acts as a potential biomarker and therapeutic target in the context of various diseases.

Emerging epigenetic-modulating therapies in lymphoma

Despite considerable advances in the treatment of lymphoma, the prognosis of patients with relapsed and/or refractory disease continues to be poor; thus, a continued need exists for the development of novel approaches and therapies. Epigenetic dysregulation might drive and/or promote tumorigenesis in various types of malignancies and is prevalent in both B cell and T cell lymphomas. Over the past decade, a large number of epigenetic-modifying agents have been developed and introduced into the clinical management of patients with haematological malignancies. In this Review, we provide a concise overview of the most promising epigenetic therapies for the treatment of lymphomas, including inhibitors of histone deacetylases (HDACs), DNA methyltransferases (DNMTs), enhancer of zeste homologue 2 (EZH2), bromodomain and extra-terminal domain proteins (BETs), protein arginine N-methyltransferases (PRMTs) and isocitrate dehydrogenases (IDHs), and highlight the most promising future directions of research in this area.

Sestrins as a Therapeutic Bridge between ROS and Autophagy in Cancer

The regulation of Reactive Oxygen Species (ROS) levels and the contribution therein from networks regulating cell metabolism, such as autophagy and the mTOR-dependent nutrient-sensing pathway, constitute major targets for selective therapeutic intervention against several types of tumors, due to their extensive rewiring in cancer cells as compared to healthy cells. Here, we discuss the sestrin family of proteins—homeostatic transducers of oxidative stress, and drivers of antioxidant and metabolic adaptation—as emerging targets for pharmacological intervention. These adaptive regulators lie at the intersection of those two priority nodes of interest in antitumor intervention—ROS control and the regulation of cell metabolism and autophagy—therefore, they hold the potential not only for the development of completely novel compounds, but also for leveraging on synergistic strategies with current options for tumor therapy and classification/stadiation to achieve personalized medicine.

Emerging Roles of Sestrins in Neurodegenerative Diseases: Counteracting Oxidative Stress and Beyond

Low levels of reactive oxygen species (ROS) are critical for the operation of regular neuronal function. However, heightened oxidative stress with increased contents of oxidation markers in DNA, lipids, and proteins with compromised antioxidant capacity may play a harmful role in the brain and may be implicated in the pathophysiology of neurodegenerative diseases. Sestrins, a family of evolutionarily-conserved stress-inducible proteins, are actively regulated by assorted stresses, such as DNA damage, hypoxia, and oxidative stress. Three highly homologous genes that encode sestrin1, sestrin2, and sestrin3 proteins exist in the genomes of vertebrates. Under stressful conditions, sestrins are activated with versatile functions to cope with different types of stimuli. A growing body of evidence suggests that sestrins, especially sestrin2, can counteract oxidative stress, lessen mammalian/mechanistic target of rapamycin (mTOR) expression, and promote cell survival, thereby playing a critical role in aging-related disorders including neurodegeneration. Strategies capable of augmenting sestrin expression may; thus, facilitate cell adaptation to stressful conditions or environments through stimulation of antioxidant response and autophagy process, which may carry clinical significance in neurodegenerative diseases.

Targeting mTOR for cancer therapy

Mechanistic target of rapamycin (mTOR) is a protein kinase regulating cell growth, survival, metabolism, and immunity. mTOR is usually assembled into several complexes such as mTOR complex 1/2 (mTORC1/2). In cooperation with raptor, rictor, LST8, and mSin1, key components in mTORC1 or mTORC2, mTOR catalyzes the phosphorylation of multiple targets such as ribosomal protein S6 kinase β-1 (S6K1), eukaryotic translation initiation factor 4E binding protein 1 (4E-BP1), Akt, protein kinase C (PKC), and type-I insulin-like growth factor receptor (IGF-IR), thereby regulating protein synthesis, nutrients metabolism, growth factor signaling, cell growth, and migration. Activation of mTOR promotes tumor growth and metastasis. Many mTOR inhibitors have been developed to treat cancer. While some of the mTOR inhibitors have been approved to treat human cancer, more mTOR inhibitors are being evaluated in clinical trials. Here, we update recent advances in exploring mTOR signaling and the development of mTOR inhibitors for cancer therapy. In addition, we discuss the mechanisms underlying the resistance to mTOR inhibitors in cancer cells.

Follicular lymphoma-associated mutations in vacuolar ATPase ATP6V1B2 activate autophagic flux and mTOR

The discovery of recurrent mutations in subunits of the vacuolar-type H+-translocating ATPase (v-ATPase) in follicular lymphoma (FL) highlights a role for the amino acid- and energy-sensing pathway to mTOR in the pathogenesis of this disease. Here, through the use of complementary experimental approaches involving mammalian cells and Saccharomyces cerevisiae, we have demonstrated that mutations in the human v-ATPase subunit ATP6V1B2 (also known as Vma2 in yeast) activate autophagic flux and maintain mTOR/TOR in an active state. Engineered lymphoma cell lines and primary FL B cells carrying mutated ATP6V1B2 demonstrated a remarkable ability to survive low leucine concentrations. The treatment of primary FL B cells with inhibitors of autophagy uncovered an addiction for survival for FL B cells harboring ATP6V1B2 mutations. These data support the idea of mutational activation of autophagic flux by recurrent hotspot mutations in ATP6V1B2 as an adaptive mechanism in FL pathogenesis and as a possible new therapeutically targetable pathway.

Germinal center-derived lymphomas: The darkest side of humoral immunity

One of the unusual features of germinal center (GC) B cells is that they manifest many hallmarks of cancer cells. Accordingly, most B-cell neoplasms originate from the GC reaction, and characteristically display abundant point mutations, structural genomic lesions, and clonal diversity from the genetic and epigenetic standpoints. The dominant biological theme of GC-derived lymphomas is mutation of genes involved in epigenetic regulation and immune receptor signaling, which come into play at critical transitional stages of the GC reaction. Hence, mechanistic studies of these mutations reveal fundamental insight into the biology of the normal and malignant GC B cell. The BCL6 transcription factor plays a central role in establishing the GC phenotype in B cells, and most lymphomas are dependent on BCL6 to maintain survival, proliferation, and perhaps immune evasion. Many lymphoma mutations have the commonality of enhancing the oncogenic functions of BCL6, or overcoming some of its tumor suppressive effects. Herein, we discuss how unique features of the GC reaction create vulnerabilities that select for particular lymphoma mutations. We examine the interplay between epigenetic programming, metabolism, signaling, and immune regulatory mechanisms in lymphoma, and discuss how these are leading to novel precision therapy strategies to treat lymphoma patients.

EZH2 oncogenic mutations drive epigenetic, transcriptional, and structural changes within chromatin domains

Chromatin is organized into topologically associating domains (TADs) enriched in distinct histone marks. In cancer, gain-of-function mutations in the gene encoding the enhancer of zeste homolog 2 protein (EZH2) lead to a genome-wide increase in histone-3 Lys27 trimethylation (H3K27me3) associated with transcriptional repression. However, the effects of these epigenetic changes on the structure and function of chromatin domains have not been explored. Here, we found a functional interplay between TADs and epigenetic and transcriptional changes mediated by mutated EZH2. Altered EZH2 (p.Tyr646* (EZH2^Y646X)) led to silencing of entire domains, synergistically inactivating multiple tumor suppressors. Intra-TAD gene silencing was coupled with changes of interactions between gene promoter regions. Notably, gene expression and chromatin interactions were restored by pharmacological inhibition of EZH2^Y646X. Our results indicate that EZH2^Y646X alters the topology and function of chromatin domains to promote synergistic oncogenic programs.

Biological Aspects of mTOR in Leukemia

The mammalian target of rapamycin (mTOR) is a central processor of intra- and extracellular signals, regulating many fundamental cellular processes such as metabolism, growth, proliferation, and survival. Strong evidences have indicated that mTOR dysregulation is deeply implicated in leukemogenesis. This has led to growing interest in the development of modulators of its activity for leukemia treatment. This review intends to provide an outline of the principal biological and molecular functions of mTOR. We summarize the current understanding of how mTOR interacts with microRNAs, with components of cell metabolism, and with controllers of apoptotic machinery. Lastly, from a clinical/translational perspective, we recapitulate the therapeutic results in leukemia, obtained by using mTOR inhibitors as single agents and in combination with other compounds.

Critical influences on the pathogenesis of follicular lymphoma

The development of follicular lymphoma (FL) from a founder B cell with an upregulation of B-cell lymphoma 2 (BCL2), via the t(14;18) translocation, to a proliferating clone, poised to undergo further transformation to an aggressive lymphoma, illustrates the opportunistic Darwinian process of tumorigenesis. Protection against apoptosis allows an innocent cell to persist and divide, with dangerous accumulation of further mutational changes, commonly involving inactivation of chromatin-modifying genes. But this is not all. FL cells reflect normal B cells in relying on expression of surface immunoglobulin. In doing so, they add another supportive mechanism by exploiting the natural process of somatic hypermutation of the IGV genes. Positive selection of motifs for addition of glycan into the antigen-binding sites of virtually all cases, and the placement of unusual mannoses in those sites, reveals a posttranslational strategy to engage the microenvironment. A bridge between mannosylated surface immunoglobulin of FL cells and macrophage-expressed dendritic cell-specific ICAM-3-grabbing nonintegrin produces a persistent low-level signal that appears essential for life in the hostile germinal center. Early-stage FL therefore requires a triad of changes: protection from apoptosis, mutations in chromatin modifiers, and an ability to interact with lectin-expressing macrophages. These changes are common and persistent. Genetic/epigenetic analysis is providing important data but investigation of the posttranslational landscape is the next challenge. We have one glimpse of its operation via the influence of added glycan on the B-cell receptor of FL. The consequential interaction with environmental lectins illustrates how posttranslational modifications can be exploited by tumor cells, and could lead to new approaches to therapy.

EZH2 Represses the B Cell Transcriptional Program and Regulates Antibody-Secreting Cell Metabolism and Antibody Production

Epigenetic remodeling is required during B cell differentiation. However, little is known about the direct functions of epigenetic enzymes in Ab-secreting cells (ASC) in vivo. In this study, we examined ASC differentiation independent of T cell help and germinal center reactions using mice with inducible or B cell-specific deletions of Ezh2 Following stimulation with influenza virus or LPS, Ezh2-deficient ASC poorly proliferated and inappropriately maintained expression of inflammatory pathways, B cell-lineage transcription factors, and Blimp-1-repressed genes, leading to fewer and less functional ASC. In the absence of EZH2, genes that normally gained histone H3 lysine 27 trimethylation were dysregulated and exhibited increased chromatin accessibility. Furthermore, EZH2 was also required for maximal Ab secretion by ASC, in part due to reduced mitochondrial respiration, impaired glucose metabolism, and poor expression of the unfolded-protein response pathway. Together, these data demonstrate that EZH2 is essential in facilitating epigenetic changes that regulate ASC fate, function, and metabolism.

Pathogenesis of follicular lymphoma

Follicular lymphoma (FL) is presented as a germinal centre B cell lymphoma that is characterized by an indolent clinical course, but remains - paradoxically - largely incurable to date. The last years have seen significant progress in our understanding of FL lymphomagenesis, which is a multi-step process beginning in the bone marrow with the hallmark t(14;18)(q32;q21) translocation. The pathobiology of FL is complex and combines broad somatic changes at the level of both the genome and the epigenome, the latter evidenced by highly recurrent mutations in chromatin-modifying genes such as KMT2D and CREBBP. While the importance of the FL microenvironment has since long been well understood, it has become evident that somatic lesions within tumour cells re-educate normal immune and stromal cells to their advantage. Enhanced understanding of FL pathogenesis is currently leading to refined therapeutic targeting of perturbed biology, paving the way for precision medicine in this lymphoma subtype.

Sestrin1, a tumor suppressor that can be rescued

SESTRIN1 is a tumor suppressor in follicular lymphoma that controls mTORC1 activity and it is inactivated by chromosomal deletions or epigenetically silenced by mutant EZH2^Y641X. Pharmacological inhibition of EZH2 promotes SESTRIN1 re-expression and it restores its tumor suppressive activity, suggesting the possibility to epigenetically control mTORC1 activity.

Papers of note in Science Translational Medicine (396)

This week’s articles describe ways to potentially treat lymphoma and fatty liver–associated fibrosis.