RESUMO
INTRODUCTION: Gastric cancer remains a formidable challenge in oncology with high mortality rates and few advancements in treatment. Claudin-18.2 (CLDN18.2) is a tight junction protein primarily expressed in the stomach and is frequently overexpressed in certain subsets of gastric cancers. Targeting CLDN18.2 with monoclonal antibodies, such as zolbetuximab (IMAB362), has shown promising efficacy results in combination with chemotherapy. AREAS COVERED: The molecular cell biology of CLDN18.2 is discussed along with studies demonstrating the utility of CLDN18.2 expression as a biomarker and therapeutic target. Important clinical studies are reviewed, including Phase III trials, SPOTLIGHT and GLOW, which demonstrate the efficacy of zolbetuximab in combination with chemotherapy in patients with CLDN18.2-positive advanced gastric cancer. EXPERT OPINION: CLDN18.2 is involved in gastric differentiation through maintenance of epithelial barrier function and coordination of signaling pathways, and its expression in gastric cancers reflects a 'gastric differentiation' program. Targeting Claudin-18.2 represents the first gastric cancer specific 'targeted' treatment. Further studies are needed to determine its role within current gastric cancer treatment sequencing, including HER2-targeted therapies and immunotherapies. Management strategies will also be needed to better mitigate zolbetuximab-related treatment side effects, including gastrointestinal (GI) toxicities.
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Anticorpos Monoclonais , Claudinas , Desenvolvimento de Medicamentos , Neoplasias Gástricas , Humanos , Neoplasias Gástricas/tratamento farmacológico , Neoplasias Gástricas/patologia , Animais , Anticorpos Monoclonais/farmacologia , Anticorpos Monoclonais/administração & dosagem , Claudinas/metabolismo , Descoberta de Drogas/métodos , Protocolos de Quimioterapia Combinada Antineoplásica/farmacologia , Protocolos de Quimioterapia Combinada Antineoplásica/administração & dosagem , Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Antineoplásicos/farmacologia , Antineoplásicos/administração & dosagem , Biomarcadores Tumorais/metabolismoRESUMO
Upper gastroesophageal carcinomas consist of cancers arising from the esophagus and stomach. Squamous cell carcinomas and adenocarcinomas are seen in the esophagus and despite arising from the same organ have different biology. Gastric adenocarcinomas are categorized into 4 molecular subtypes: high Epstein-Barr virus load, microsatellite unstable cancers, chromosomal unstable (CIN) cancers, and genomically stable cancers. Genomically stable gastric cancers correlate highly with histologically defined diffuse-type cancers. Esophageal carcinomas and CIN gastric cancers often are driven by high-level amplifications of oncogenes and contain a high degree of intratumoral heterogeneity. Targeted therapeutics is an active area of research for gastroesophageal cancers.
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Adenocarcinoma , Neoplasias Esofágicas , Neoplasias Gástricas , Humanos , Adenocarcinoma/patologia , Adenocarcinoma/diagnóstico , Adenocarcinoma/genética , Carcinoma de Células Escamosas/diagnóstico , Carcinoma de Células Escamosas/genética , Carcinoma de Células Escamosas/patologia , Neoplasias Esofágicas/patologia , Neoplasias Esofágicas/diagnóstico , Neoplasias Esofágicas/genética , Neoplasias Gástricas/patologia , Neoplasias Gástricas/diagnóstico , Neoplasias Gástricas/genéticaRESUMO
PURPOSE OF REVIEW: Barrett's esophagus (BE) is the number one risk factor for developing esophageal adenocarcinoma (EAC), a deadly cancer with limited treatment options that has been increasing in incidence in the US. In this report, we discuss current studies on the role of mesenchyme and cancer-associated fibroblasts (CAFs) in BE and EAC, and we highlight translational prospects of targeting these cells. RECENT FINDINGS: New insights through studies using single-cell RNA sequencing (sc-RNA seq) have revealed an important emerging role of the mesenchyme in developmental signaling and cancer initiation. BE and EAC share similar stromal gene expression, as functional classifications of nonepithelial cells in BE show a remarkable similarity to EAC CAFs. Several recent sc-RNA seq studies and novel organoid fibroblast co-culture systems have characterized the subgroups of fibroblasts in BE and EAC, and have shown that these cells can directly influence the epithelium to induce BE development and cancer progression. Targeting the CAFs in EAC with may be a promising novel therapeutic strategy. SUMMARY: The fibroblasts in the surrounding mesenchyme may have a direct role in influencing altered epithelial plasticity during BE development and progression to EAC.
Assuntos
Adenocarcinoma , Esôfago de Barrett , Fibroblastos Associados a Câncer , Neoplasias Esofágicas , Fibroblastos , Esôfago de Barrett/patologia , Humanos , Neoplasias Esofágicas/patologia , Neoplasias Esofágicas/genética , Adenocarcinoma/patologia , Fibroblastos Associados a Câncer/patologia , Fibroblastos Associados a Câncer/metabolismo , Fibroblastos/metabolismo , Fibroblastos/patologia , Progressão da DoençaRESUMO
Introduction: Plasticity is an inherent property of the normal gastrointestinal tract allowing for appropriate response to injury and healing. However, the aberrancy of adaptable responses is also beginning to be recognized as a driver during cancer development and progression. Gastric and esophageal malignancies remain leading causes of cancer-related death globally as there are limited early disease diagnostic tools and paucity of new effective treatments. Gastric and esophageal adenocarcinomas share intestinal metaplasia as a key precancerous precursor lesion. Methods: Here, we utilize an upper GI tract patient-derived tissue microarray that encompasses the sequential development of cancer from normal tissues to illustrate the expression of a set of metaplastic markers. Results: We report that in contrast to gastric intestinal metaplasia, which has traits of both incomplete and complete intestinal metaplasia, Barrett's esophagus (i.e., esophageal intestinal metaplasia) demonstrates hallmarks of incomplete intestinal metaplasia. Specifically, this prevalent incomplete intestinal metaplasia seen in Barrett's esophagus manifests as concurrent development and expression of both gastric and intestinal traits. Additionally, many gastric and esophageal cancers display a loss of or a decrease in these characteristic differentiated cell properties, demonstrating the plasticity of molecular pathways associated with the development of these cancers. Discussion: Further understanding of the commonalities and differences governing the development of upper GI tract intestinal metaplasias and their progression to cancer will lead to improved diagnostic and therapeutic avenues.
RESUMO
Gastric cancer is a major source of global cancer mortality with limited treatment options and poor patient survival. As our molecular understanding of gastric cancer improves, we are now beginning to recognize that these cancers are a heterogeneous group of diseases with incredibly unique pathogeneses and active oncogenic pathways. It is this molecular diversity and oftentimes lack of common oncogenic driver mutations that bestow the poor treatment responses that oncologists often face when treating gastric cancer. In this review, we will examine the treatments for gastric cancer including up-to-date molecularly targeted therapies and immunotherapies. We will then review the molecular subtypes of gastric cancer to highlight the diversity seen in this disease. We will then shift our discussion to basic science and gastric cancer mouse models as tools to study gastric cancer molecular heterogeneity. Furthermore, we will elaborate on a molecular process termed paligenosis and the cyclical hit model as key events during gastric cancer initiation that impart nondividing mature differentiated cells the ability to re-enter the cell cycle and accumulate disparate genomic mutations during years of chronic inflammation and injury. As our basic science understanding of gastric cancer advances, so too must our translational and clinical efforts. We will end with a discussion regarding single-cell molecular analyses and cancer organoid technologies as future translational avenues to advance our understanding of gastric cancer heterogeneity and to design precision-based gastric cancer treatments. Elucidation of interpatient and intratumor heterogeneity is the only way to advance future cancer prevention, diagnoses and treatment.
Assuntos
Neoplasias Gástricas , Camundongos , Animais , Humanos , Neoplasias Gástricas/genética , Neoplasias Gástricas/terapia , Terapia de Alvo Molecular , Carcinogênese , Medicina de Precisão , MutaçãoRESUMO
Upper gastroesophageal carcinomas consist of cancers arising from the esophagus and stomach. Squamous cell carcinomas and adenocarcinomas are seen in the esophagus and despite arising from the same organ have different biology. Gastric adenocarcinomas are categorized into 4 molecular subtypes: high Epstein-Barr virus load, microsatellite unstable cancers, chromosomal unstable (CIN) cancers, and genomically stable cancers. Genomically stable gastric cancers correlate highly with histologically defined diffuse-type cancers. Esophageal carcinomas and CIN gastric cancers often are driven by high-level amplifications of oncogenes and contain a high degree of intratumoral heterogeneity. Targeted therapeutics is an active area of research for gastroesophageal cancers.
Assuntos
Infecções por Vírus Epstein-Barr , Neoplasias Gástricas , Infecções por Vírus Epstein-Barr/genética , Herpesvirus Humano 4 , Humanos , Imuno-Histoquímica , Patologia Molecular , Neoplasias Gástricas/genéticaRESUMO
In October 2020, the Keystone Symposia Global Health Series hosted a Keystone eSymposia entitled 'Tissue Plasticity: Preservation and Alteration of Cellular Identity'. The event synthesized groundbreaking research from unusually diverse fields of study, presented in various formats, including live and virtual talks, panel discussions and interactive e-poster sessions. The meeting focused on cell identity changes and plasticity in multiple tissues, species and developmental contexts, both in homeostasis and during injury. Here, we review the key themes of the meeting: (1) cell-extrinsic drivers of plasticity; (2) epigenomic regulation of cell plasticity; and (3) conserved mechanisms governing plasticity. A salient take-home conclusion was that there may be conserved mechanisms used by cells to execute plasticity, with autodegradative activity (autophagy and lysosomes) playing a crucial initial step in diverse organs and organisms.
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Plasticidade Celular/efeitos dos fármacos , Plasticidade Celular/fisiologia , Cimentos de Resina/farmacologia , Animais , Transdiferenciação Celular/fisiologia , Reprogramação Celular/fisiologia , Homeostase , Humanos , MetaplasiaRESUMO
Gastroesophageal cancers are leading causes of cancer death. Our attempts at adopting molecularly based treatment approaches have been slow and ineffective even though we begin to identify specific targetable gene mutations and pathways. It is clear that we should no longer treat all gastroesophageal cancers as a homogeneous disease, which is what we do when we use non-specific chemotherapy. However, we currently cannot monitor successful gene/pathway targeting, nor understand how/when tumors develop resistance, nor predict which patients will derive maximal benefit. To improve outcomes, we must precisely detail the heterogeneity of these tumors to then individualize cancer therapy as well as develop novel avenues to study and predict treatment effects in individual patients. To this end, patient-derived organoids, in which tumor cells from individual patients are grown in a Petri dish, are a new versatile system that allows for timely expandability, detailed molecular characterization, and genetic manipulation with the promise of enabling predictive assessment of treatment response. In this review, we will explore the development and basic techniques for organoid generation, and discuss the current and potential future applications of this exciting technology to study the basic science of carcinogenesis and to predict/guide cancer patient care in the clinics.
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Neoplasias Esofágicas/patologia , Organoides/patologia , Neoplasias Gástricas/patologia , Animais , Carcinogênese/patologia , Humanos , Pesquisa Translacional BiomédicaRESUMO
Importance: Standard first-line regimens for patients with metastatic gastroesophageal adenocarcinomas have an approximate 40% objective response rate (ORR). The combination of leucovorin, fluorouracil, irinotecan, and oxaliplatin (FOLFIRINOX) has been efficacious as first-line therapy for other gastrointestinal cancers, such as pancreatic and colon cancers. Objective: To evaluate the clinical activity and safety of FOLFIRINOX as first-line treatment for patients with advanced gastroesophageal adenocarcinoma. Design, Setting, and Participants: This is an open-label, single-arm phase 2 study of first-line FOLFIRINOX in patients with advanced gastroesophageal adenocarcinoma. Estimated sample size included 41 patients with ERBB2-negative disease with 90% power to detect an ORR of 60% or greater with α of .10. No enrollment goal was planned for ERBB2-positive patients, but they were allowed to receive trastuzumab in combination with FOLFIRINOX. Interventions: Starting doses were fluorouracil, 400 mg/m2 bolus, followed by 2400 mg/m2 over 46 hours; leucovorin, 400 mg/m2; irinotecan, 180 mg/m2; and oxaliplatin, 85 mg/m2. Trastuzumab was administered as a 6 mg/kg loading dose, followed by 4 mg/kg every 14 days in patients with ERBB2-positive disease. Main Outcomes and Measures: The primary end point was ORR by the Response Evaluation Criteria in Solid Tumors, version 1.1. Secondary end points included safety profile, progression-free survival (PFS), overall survival (OS), and duration of response. Results: From November 2013 to May 2018, 67 patients were enrolled (median [range] age, 59.0 [34-78] years; including 56 [84%] men), and 26 of 67 (39%) had ERBB2-positive disease. Median follow-up was 17.4 months. The ORR was 61%(95% CI, 44.5%-75.8%) (25 of 41) in the ERBB2-negative group and 85% (95% CI, 65.1%-95.6%) (22 of 26) in the ERBB2-positive group, including 1 patient with complete response. For ERBB2-negative patients, median PFS was 8.4 months and median OS was 15.5 months; for ERBB2-positive patients, median PFS was 13.8 months and median OS was 19.6 months. Fifty-six patients (84%) had dose modifications or treatment delays. The most common toxic effects were neutropenia (91%, n = 61), diarrhea (63%, n = 42), peripheral sensory neuropathy (61%, n = 41), and nausea (48%, n = 32), with no unexpected toxic effects. Conclusions and Relevance: The FOLFIRINOX regimen with or without trastuzumab was associated with improved ORR and PFS in patients with advanced gastroesophageal adenocarcinoma in the first-line setting. This regimen may be a reasonable therapeutic option for patients with preserved performance status. Trial Registration: ClinicalTrials.gov Identifier: NCT01928290.
Assuntos
Adenocarcinoma/tratamento farmacológico , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Neoplasias Esofágicas/tratamento farmacológico , Neoplasias Gástricas/tratamento farmacológico , Trastuzumab/uso terapêutico , Adulto , Idoso , Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Diarreia/induzido quimicamente , Feminino , Fluoruracila/efeitos adversos , Fluoruracila/uso terapêutico , Humanos , Irinotecano/efeitos adversos , Irinotecano/uso terapêutico , Leucovorina/efeitos adversos , Leucovorina/uso terapêutico , Masculino , Pessoa de Meia-Idade , Náusea/induzido quimicamente , Neutropenia/induzido quimicamente , Oxaliplatina/efeitos adversos , Oxaliplatina/uso terapêutico , Doenças do Sistema Nervoso Periférico/induzido quimicamente , Trastuzumab/efeitos adversos , Resultado do TratamentoRESUMO
PURPOSE OF REVIEW: In this review, we explore a paligenosis-based model to explain Barrett's esophagus development and progression: 'the cyclical hit model.' RECENT FINDINGS: Genomic analyses have highlighted the high mutational burden of esophageal adenocarcinoma, Barrett's esophagus, and even normal esophageal epithelium. Somatic mutations in key genes including TP53 occur early in the neoplastic progression sequence of Barrett's esophagus, whereas chromosomal amplification resulting in oncogene activation occurs as a critical late event. Paligenosis is a shared injury response mechanism characterized by activation of autophagy, expression of progenitor markers, and increased mTORC signaling-induced cell-cycle reentry. In the setting of chronic injury/inflammation, cycles of paligenosis may allow accumulation of mutations until eventually the mutational burden, in concert perhaps with mutations in key driver oncogenes, finally alters the cell's ability to redifferentiate, leading to the emergence of a potential neoplastic clone. SUMMARY: Under conditions of chronic gastroesophageal refluxate exposure, the normal esophageal squamous epithelium might undergo multiple cycles of paligenosis, allowing initially silent mutations to accumulate until key events impart mutant clones with an oncogenic survival advantage.
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Adenocarcinoma , Esôfago de Barrett , Neoplasias Esofágicas , Adenocarcinoma/genética , Esôfago de Barrett/genética , Neoplasias Esofágicas/genética , Humanos , Mutação , Transdução de SinaisRESUMO
Chronic injury and inflammation in the esophagus can cause a change in cellular differentiation known as metaplasia. Most commonly, the differentiation changes manifest as Barrett's esophagus (BE), characterized by the normal stratified squamous epithelium converting into a cuboidal-columnar, glandular morphology. BE cells can phenotypically resemble specific normal cell types of the stomach or intestine, or they can have overlapping phenotypes in disorganized admixtures. The stomach can also undergo metaplasia characterized by aberrant gastric or intestinal differentiation patterns. In both organs, it has been argued that metaplasia may represent a recapitulation of the embryonic or juvenile gastrointestinal tract, as cells access a developmental progenitor genetic program that can help repair damaged tissue. Here, we review the normal development of esophagus and stomach, and describe how BE represents an intermixing of cells resembling gastric pseudopyloric (SPEM) and intestinal metaplasia. We discuss a cellular process recently termed "paligenosis" that governs how mature, differentiated cells can revert to a proliferating progenitor state in metaplasia. We discuss the "Cyclical Hit" theory in which paligenosis might be involved in the increased risk of metaplasia for progression to cancer. However, somatic mutations might occur in proliferative phases and then be warehoused upon redifferentiation. Through years of chronic injury and many rounds of paligenosis and dedifferentiation, eventually a cell with a mutation that prevents dedifferentiation may arise and clonally expand fueling stable metaplasia and potentially thereafter acquiring additional mutations and progressing to dysplasia and cancer.
Assuntos
Esôfago de Barrett/patologia , Células Epiteliais , Esôfago/patologia , Estômago/patologia , Desdiferenciação Celular , Transdiferenciação Celular , Evolução Clonal , Células Epiteliais/patologia , Células Epiteliais/fisiologia , Humanos , MetaplasiaRESUMO
We hypothesized that basic helix-loop-helix (bHLH) MIST1 (BHLHA15) is a "scaling factor" that universally establishes secretory morphology in cells that perform regulated secretion. Here, we show that targeted deletion of MIST1 caused dismantling of the secretory apparatus of diverse exocrine cells. Parietal cells (PCs), whose function is to pump acid into the stomach, normally lack MIST1 and do not perform regulated secretion. Forced expression of MIST1 in PCs caused them to expand their apical cytoplasm, rearrange mitochondrial/lysosome trafficking, and generate large secretory granules. Mist1 induced a cohort of genes regulated by MIST1 in multiple organs but did not affect PC function. MIST1 bound CATATG/CAGCTG E boxes in the first intron of genes that regulate autophagosome/lysosomal degradation, mitochondrial trafficking, and amino acid metabolism. Similar alterations in cell architecture and gene expression were also caused by ectopically inducing MIST1 in vivo in hepatocytes. Thus, MIST1 is a scaling factor necessary and sufficient by itself to induce and maintain secretory cell architecture. Our results indicate that, whereas mature cell types in each organ may have unique developmental origins, cells performing similar physiological functions throughout the body share similar transcription factor-mediated architectural "blueprints."
Assuntos
Regulação da Expressão Gênica/genética , Fator de Crescimento de Hepatócito/genética , Fator de Crescimento de Hepatócito/metabolismo , Células Parietais Gástricas/citologia , Proteínas Proto-Oncogênicas/genética , Proteínas Proto-Oncogênicas/metabolismo , Via Secretória/genética , Células Acinares/citologia , Células Acinares/efeitos dos fármacos , Células Acinares/metabolismo , Animais , Antineoplásicos Hormonais/farmacologia , Linhagem Celular , Expressão Ectópica do Gene/efeitos dos fármacos , Deleção de Genes , Regulação da Expressão Gênica/efeitos dos fármacos , Camundongos , Células Parietais Gástricas/efeitos dos fármacos , Células Parietais Gástricas/metabolismo , Células Parietais Gástricas/ultraestrutura , Tamoxifeno/farmacologiaRESUMO
The transcription factor, X-box-binding protein-1 (XBP1), controls the development and maintenance of the endoplasmic reticulum (ER) in multiple secretory cell lineages. We show here that Hepatocyte Nuclear Factor 4α (HNF4α) directly induces XBP1 expression. Mutations in HNF4α cause Mature-Onset Diabetes of the Young I (MODYI), a subset of diabetes characterized by diminished GSIS. In mouse models, cell lines, and ex vivo islets, using dominant negative and human- disease-allele point mutants or knock-out and knockdown models, we show that disruption of HNF4α caused decreased expression of XBP1 and reduced cellular ER networks. GSIS depends on ER Ca(2+) signaling; we show that diminished XBP1 and/or HNF4α in ß-cells led to impaired ER Ca(2+) homeostasis. Restoring XBP1 expression was sufficient to completely rescue GSIS in HNF4α-deficient ß-cells. Our findings uncover a transcriptional relationship between HNF4α and Xbp1 with potentially broader implications about MODYI and the importance of transcription factor signaling in the regulation of secretion.
Assuntos
Proteínas de Ligação a DNA/genética , Fator 4 Nuclear de Hepatócito/fisiologia , Células Secretoras de Insulina/fisiologia , Fatores de Transcrição/genética , Transcrição Gênica , Animais , Cálcio/metabolismo , Linhagem Celular , Proteínas de Ligação a DNA/metabolismo , Diabetes Mellitus Tipo 2/genética , Retículo Endoplasmático/metabolismo , Regulação da Expressão Gênica , Glucose/fisiologia , Células HEK293 , Homeostase , Humanos , Insulina/metabolismo , Secreção de Insulina , Camundongos , Fatores de Transcrição de Fator Regulador X , Fatores de Transcrição/metabolismo , Proteína 1 de Ligação a X-BoxRESUMO
Injury and inflammation in the gastric epithelium can cause disruption of the pathways that guide the differentiation of cell lineages, which in turn can cause persistent alterations in differentiation patterns, known as metaplasia. Metaplasia that occurs in the stomach is associated with increased risk for cancer. Methods for isolating distinct gastric epithelial cell populations would facilitate dissection of the molecular and cellular pathways that guide normal and metaplastic differentiation. Here, we identify alanyl aminopeptidase (CD13) as a specific surface marker of zymogenic chief cells (ZCs) in the gastric epithelium. We show that 1) among gastric epithelial cells alanyl aminopeptidase expression is confined to mature ZCs, and 2) its expression is lost en route to metaplasia in both mouse and human stomachs. With this new marker coupled with new techniques that we introduce for dissociating gastric epithelial cells and overcoming their constitutive autofluorescence, we are able to reliably isolate enriched populations of ZCs for both molecular analysis and for the establishment of ZC-derived ex vivo gastroid cultures.
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Antígenos CD13/metabolismo , Separação Celular/métodos , Celulas Principais Gástricas/enzimologia , Estômago/enzimologia , Proteínas Adaptadoras de Transdução de Sinal , Animais , Biomarcadores/metabolismo , Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Células Cultivadas , Celulas Principais Gástricas/patologia , Feminino , Humanos , Masculino , Metaplasia , Camundongos Endogâmicos C57BL , Camundongos Knockout , Fenótipo , Estômago/patologiaRESUMO
As they mature, professional secretory cells like pancreatic acinar and gastric chief cells induce the transcription factor MIST1 (also known as BHLHA15) to substantially scale up production of large secretory granules in a process that involves expansion of apical cytoplasm and redistribution of lysosomes and mitochondria. How a scaling factor like MIST1 rearranges cellular architecture simply by regulating expression levels of its transcriptional targets is unknown. RAB26 is a MIST1 target whose role in MIST1-mediated secretory cell maturation is also unknown. Here, we confirm that RAB26 expression, unlike most Rabs which are ubiquitously expressed, is tissue specific and largely confined to MIST1-expressing secretory tissues. Surprisingly, functional studies showed that RAB26 predominantly associated with LAMP1/cathepsin D lysosomes and not directly with secretory granules. Moreover, increasing RAB26 expression - by inducing differentiation of zymogen-secreting cells or by direct transfection - caused lysosomes to coalesce in a central, perinuclear region. Lysosome clustering in turn caused redistribution of mitochondria into distinct subcellular neighborhoods. The data elucidate a novel function for RAB26 and suggest a mechanism for how cells could increase transcription of key effectors to reorganize subcellular compartments during differentiation.
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Lisossomos/metabolismo , Mitocôndrias/metabolismo , Proteínas rab de Ligação ao GTP/fisiologia , Sequência de Aminoácidos , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Sítios de Ligação , Linhagem Celular Tumoral , Humanos , Proteínas de Membrana Lisossomal/metabolismo , Lisossomos/ultraestrutura , Mitocôndrias/ultraestrutura , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Especificidade de Órgãos , Mutação Puntual , Transporte Proteico , Proteínas rab de Ligação ao GTP/metabolismo , proteínas de unión al GTP Rab7RESUMO
After cell fate specification, differentiating cells must amplify the specific subcellular features required for their specialized function. How cells regulate such subcellular scaling is a fundamental unanswered question. Here, we show that the E3 ubiquitin ligase Mindbomb 1 (MIB1) is required for the apical secretory apparatus established by gastric zymogenic cells as they differentiate from their progenitors. When Mib1 was deleted, death-associated protein kinase-1 (DAPK1) was rerouted to the cell base, microtubule-associated protein 1B (MAP1B) was dephosphorylated, and the apical vesicles that normally support mature secretory granules were dispersed. Consequently, secretory granules did not mature. The transcription factor MIST1 bound the first intron of Mib1 and regulated its expression. We further showed that loss of MIB1 and dismantling of the apical secretory apparatus was the earliest quantifiable aberration in zymogenic cells undergoing transition to a precancerous metaplastic state in mouse and human stomach. Our results reveal a mechanistic pathway by which cells can scale up a specific, specialized subcellular compartment to alter function during differentiation and scale it down during disease.
Assuntos
Diferenciação Celular , Celulas Principais Gástricas/fisiologia , Ubiquitina-Proteína Ligases/fisiologia , Adenocarcinoma/enzimologia , Adenocarcinoma/patologia , Animais , Proteínas Reguladoras de Apoptose/metabolismo , Sequência de Bases , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Proteínas Quinases Dependentes de Cálcio-Calmodulina/metabolismo , Crescimento Celular , Polaridade Celular , Celulas Principais Gástricas/enzimologia , Sequência Conservada , Proteínas Quinases Associadas com Morte Celular , Humanos , Neoplasias Intestinais/enzimologia , Neoplasias Intestinais/patologia , Metaplasia/induzido quimicamente , Metaplasia/enzimologia , Metaplasia/patologia , Camundongos , Camundongos Knockout , Microtúbulos/genética , Microtúbulos/metabolismo , Transporte Proteico , Estômago/patologia , Tamoxifeno , Ubiquitina-Proteína Ligases/genética , Ubiquitina-Proteína Ligases/metabolismoRESUMO
The Cullin-RING ubiquitin-ligase CRL4 controls cell cycle and DNA damage checkpoint response and ensures genomic integrity. Inactivation of the Cul4 component of the CRL4 E3 ligase complex in Caenorhabditis elegans by RNA interference results in massive mitotic DNA re-replication in the blast cells, largely due to failed degradation of the DNA licensing protein, CDT-1, and premature spermatogenesis. Here we show that inactivation of Cul4a by gene-targeting in mice only affected male but not female fertility. This male infertility phenotype resulted from a combination of decreased spermatozoa number, reduced sperm motility and defective acrosome formation. Agenesis of the mutant germ cells was accompanied by increased cell death in pachytene/diplotene cells with markedly elevated levels of phospho-p53 and CDT-1. Despite apparent normal assembly of synaptonemal complexes and DNA double strand break repair, dissociation of MLH1, a component of the late recombination nodule, was delayed in Cul4a -/- diplotene spermatocytes, which potentially led to subsequent disruptions in meiosis II and spermiogenesis. Together, our study revealed an indispensable role for Cul4a during male germ cell meiosis.
Assuntos
Proteínas Culina/metabolismo , Meiose/genética , Espermatogênese/genética , Acrossomo/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Animais , Morte Celular/genética , Proteínas Culina/genética , Quebras de DNA de Cadeia Dupla , Reparo do DNA/genética , Infertilidade Masculina/genética , Infertilidade Masculina/metabolismo , Masculino , Camundongos , Camundongos Transgênicos , Proteína 1 Homóloga a MutL , Proteínas Nucleares/metabolismo , Fosfoproteínas/metabolismo , Contagem de Espermatozoides , Motilidade dos Espermatozoides/genética , Espermatócitos/citologia , Espermatócitos/metabolismo , Complexo Sinaptonêmico/metabolismo , Proteína Supressora de Tumor p53/metabolismoRESUMO
Little is known about how differentiating cells reorganize their cellular structure to perform specialized physiological functions. MIST1, an evolutionarily conserved transcription factor, is required for the formation of large, specialized secretory vesicles in gastric zymogenic (chief) cells (ZCs) as they differentiate from their mucous neck cell progenitors. Here, we show that MIST1 binds to highly conserved CATATG E-boxes to directly activate transcription of 6 genes, including those encoding the small GTPases RAB26 and RAB3D. We next show that RAB26 and RAB3D expression is significantly downregulated in Mist1(-)(/)(-) ZCs, suggesting that MIST1 establishes large secretory granules by inducing RAB transcription. To test this hypothesis, we transfected human gastric cancer cell lines stably expressing MIST1 with red fluorescent protein (RFP)-tagged pepsinogen C, a key secretory product of ZCs. Those cells upregulate expression of RAB26 and RAB3D to form large secretory granules, whereas control, non-MIST1-expressing cells do not. Moreover, granule formation in MIST1-expressing cells requires RAB activity because treatment with a RAB prenylation inhibitor and transfection of dominant negative RAB26 abrogate granule formation. Together, our data establish the molecular process by which a transcription factor can directly induce fundamental cellular architecture changes by increasing transcription of specific cellular effectors that act to organize a unique subcellular compartment.