scholarly journals EMBR-15. PRC2 COMPLEX ENFORCES NEURONAL LINEAGE AND SUPPRESSES TUMOR GROWTH IN SHH MEDULLOBLASTOMA

2021 ◽  
Vol 23 (Supplement_1) ◽  
pp. i8-i9
Author(s):  
Abigail Cleveland ◽  
Daniel Malawsky ◽  
Mehal Churiwal ◽  
Timothy Gershon
Keyword(s):  
Tumor Growth ◽  
Tumor Progression ◽  
Target Genes ◽  
Genetically Engineered ◽  
Developmental Studies ◽  
Loss Of Function ◽  
Cerebellar Granule Neuron ◽  
Tumor Studies ◽  
Myocyte Differentiation ◽  
Neuronal Lineage

Abstract Hyperactivation of Sonic Hedgehog (SHH) signaling pathway drives tumor progression in the largest medulloblastoma subgroup. During cerebellar development, promoters of SHH target genes show inhibitory trimethylation of histone H3 at lysine 27 (H3K27me3), mediated by the Polycomb Repressive Complex 2 (PRC2). Here, we explored the regulation of cerebellar growth and medulloblastoma tumorigenesis by PRC2 complex components EED and EZH2. For developmental studies, we conditionally deleted Eed or Ezh2 in the Atoh1 lineage that gives rise to the cerebellar granule neuron progenitors (CGNP) that are cells of origin for SHH medulloblastomas. For tumor studies, we bred the conditional Eed- or Ezh2-deleted mouse lines with mice genetically engineered to develop SHH medulloblastoma. Our developmental studies showed that Eed was absolutely required for cerebellar growth. Eed-deleted CGNPs underwent aberrant, myocyte-like differentiation and spontaneous apoptosis, resulting in cerebellar hypoplasia. In contrast, Ezh2 deletion produced no developmental phenotype, despite blocking all H3K27me3 in CGNPs. Our tumor studies showed that Eed-deleted medulloblastomas similarly showed aberrant, myocyte differentiation, but unlike CGNPs, did not undergo widespread apoptosis. Eed-deleted medulloblastomas progressed more rapidly than control tumors, indicating that the inappropriate, muscle-like differentiation did not slow tumor growth. Ezh2-deleted medulloblastomas similarly progressed more rapidly than controls. Our data show that the PRC2 complex acts to enforce neuronal lineage commitment in both development and tumorigenesis and to restrain tumor growth in SHH medulloblastoma. Myocyte differentiation in Eed-deleted tumors suggests that PRC2 loss of function may contribute to the medullomyoblastomas that have been observed in patients. The differences in developmental phenotype show that EZH2 and EED functions are non-identical and can be dissociated, while similar increase in tumor progression show tumor suppressive functions for both EED and EZH2.

scholarly journals A set of microRNAs coordinately controls tumorigenesis, invasion, and metastasis

2019 ◽  
Vol 116 (48) ◽  
pp. 24184-24195 ◽  
Author(s):  
Iacovos P. Michael ◽  
Sadegh Saghafinia ◽  
Douglas Hanahan
Keyword(s):  
Tumor Growth ◽  
Target Genes ◽  
Genetically Engineered ◽  
Malignant Progression ◽  
Metastasis Suppressor ◽  
Invasion And Metastasis ◽  
Biologically Relevant ◽  
Genetically Engineered Mouse Model ◽  
Functional Involvement

MicroRNA-mediated gene regulation has been implicated in various diseases, including cancer. This study examined the role of microRNAs (miRNAs) during tumorigenesis and malignant progression of pancreatic neuroendocrine tumors (PanNETs) in a genetically engineered mouse model. Previously, a set of miRNAs was observed to be specifically up-regulated in a highly invasive and metastatic subtype of mouse and human PanNET. Using functional assays, we now implicate different miRNAs in distinct phenotypes: miR-137 stimulates tumor growth and local invasion, whereas the miR-23b cluster enables metastasis. An algorithm, Bio-miRTa, has been developed to facilitate the identification of biologically relevant miRNA target genes and applied to these miRNAs. We show that a top-ranked miR-137 candidate gene, Sorl1, has a tumor suppressor function in primary PanNETs. Among the top targets for the miR-23b cluster, Acvr1c/ALK7 has recently been described to be a metastasis suppressor, and we establish herein that it is down-regulated by the miR-23b cluster, which is crucial for its prometastatic activity. Two other miR-23b targets, Robo2 and P2ry1, also have demonstrable antimetastatic effects. Finally, we have used the Bio-miRTa algorithm in reverse to identify candidate miRNAs that might regulate activin B, the principal ligand for ALK7, identifying thereby a third family of miRNAs—miRNA-130/301—that is congruently up-regulated concomitant with down-regulation of activin B during tumorigenesis, suggestive of functional involvement in evasion of the proapoptotic barrier. Thus, dynamic up-regulation of miRNAs during multistep tumorigenesis and malignant progression serves to down-regulate distinctive suppressor mechanisms of tumor growth, invasion, and metastasis.

scholarly journals PHD3 Acts as Tumor Suppressor in Mouse Osteosarcoma and Influences Tumor Vascularization via PDGF-C Signaling

Cancers ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 496
Author(s):  
Antje Egners ◽  
Maryam Rezaei ◽  
Aleksandar Kuzmanov ◽  
David Poitz ◽  
Doreen Streichert ◽  
...  
Keyword(s):  
Tumor Growth ◽  
Tumor Progression ◽  
Target Genes ◽  
Tumor Tissue ◽  
Hypoxia Inducible Factor ◽  
Cancer Cell Proliferation ◽  
Downstream Signaling ◽  
Protein Levels ◽  
Hypoxic Environment ◽  
Transcriptional Complex

Cancer cell proliferation and insufficient blood supply can lead to the development of hypoxic areas in the tumor tissue. The adaptation to the hypoxic environment is mediated by a transcriptional complex called hypoxia-inducible factor (HIF). HIF protein levels are tightly controlled by oxygen-dependent prolyl hydroxylase domain proteins (PHDs). However, the precise roles of these enzymes in tumor progression and their downstream signaling pathways are not fully characterized. Here, we study PHD3 function in murine experimental osteosarcoma. Unexpectedly, PHD3 silencing in LM8 cells affects neither HIF-1α protein levels, nor the expression of various HIF-1 target genes. Subcutaneous injection of PHD3-silenced tumor cells accelerated tumor progression and was accompanied by dramatic phenotypic changes in the tumor vasculature. Blood vessels in advanced PHD3-silenced tumors were enlarged whereas their density was greatly reduced. Examination of the molecular pathways underlying these alterations revealed that platelet-derived growth factor (PDGF)-C signaling is activated in the vasculature of PHD3-deficient tumors. Silencing of PDGF-C depleted tumor growth, increased vessel density and reduced vessel size. Our data show that PHD3 controls tumor growth and vessel architecture in LM8 osteosarcoma by regulating the PDGF-C pathway, and support the hypothesis that different members of the PHD family exert unique functions in tumors.

scholarly journals Context-dependent effects of whole-genome duplication during mammary tumor recurrence

2021 ◽  
Author(s):  
Rachel Newcomb ◽  
Emily Dean ◽  
James V Alvarez
Keyword(s):  
Tumor Growth ◽  
Tumor Progression ◽  
Whole Genome Duplication ◽  
Genome Duplication ◽  
Tumor Formation ◽  
Genetically Engineered ◽  
Whole Genome ◽  
Primary Tumors ◽  
Recurrent Tumors ◽  
Genetically Engineered Mouse Model

Whole-genome duplication (WGD) generates polyploid cells possessing more than two copies of the genome and is among the most common genetic abnormalities in cancer. The frequency of WGD increases in advanced and metastatic tumors, and WGD is associated with poor prognosis in diverse tumor types, suggesting a functional role for polyploidy in tumor progression. Experimental evidence suggests that polyploidy has both tumor-promoting and suppressing effects, but how polyploidy regulates tumor progression remains unclear. Using a genetically engineered mouse model of Her2-driven breast cancer, we explored the prevalence and consequences of whole-genome duplication during tumor growth and recurrence. While primary tumors in this model are invariably diploid, nearly 40% of recurrent tumors undergo WGD. WGD in recurrent tumors was associated with increased chromosomal instability, decreased proliferation and increased survival in stress conditions. The effects of WGD on tumor growth were dependent on tumor stage. Surprisingly, in recurrent tumor cells WGD slowed tumor formation, growth rate and opposed the process of recurrence, while WGD promoted the growth of primary tumors. These findings highlight the importance of identifying conditions that promote the growth of polyploid tumors, including the cooperating genetic mutations that allow cells to overcome the barriers to WGD tumor cell growth and proliferation.

scholarly journals Context-dependent effects of whole-genome duplication during mammary tumor recurrence

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Rachel Newcomb ◽  
Emily Dean ◽  
Brock J. McKinney ◽  
James V. Alvarez
Keyword(s):  
Tumor Growth ◽  
Tumor Progression ◽  
Whole Genome Duplication ◽  
Genome Duplication ◽  
Tumor Formation ◽  
Genetically Engineered ◽  
Whole Genome ◽  
Primary Tumors ◽  
Recurrent Tumors ◽  
Genetically Engineered Mouse Model

AbstractWhole-genome duplication (WGD) generates polyploid cells possessing more than two copies of the genome and is among the most common genetic abnormalities in cancer. The frequency of WGD increases in advanced and metastatic tumors, and WGD is associated with poor prognosis in diverse tumor types, suggesting a functional role for polyploidy in tumor progression. Experimental evidence suggests that polyploidy has both tumor-promoting and suppressing effects, but how polyploidy regulates tumor progression remains unclear. Using a genetically engineered mouse model of Her2-driven breast cancer, we explored the prevalence and consequences of whole-genome duplication during tumor growth and recurrence. While primary tumors in this model are invariably diploid, nearly 40% of recurrent tumors undergo WGD. WGD in recurrent tumors was associated with increased chromosomal instability, decreased proliferation and increased survival in stress conditions. The effects of WGD on tumor growth were dependent on tumor stage. Surprisingly, in recurrent tumor cells WGD slowed tumor formation, growth rate and opposed the process of recurrence, while WGD promoted the growth of primary tumors. These findings highlight the importance of identifying conditions that promote the growth of polyploid tumors, including the cooperating genetic mutations that allow cells to overcome the barriers to WGD tumor cell growth and proliferation.

scholarly journals Intrabodies targeting human papillomavirus 16 E6 and E7 oncoproteins for therapy of established HPV-associated tumors

2021 ◽  
Vol 40 (1) ◽  
Author(s):  
Francesca Paolini ◽  
Carla Amici ◽  
Mariantonia Carosi ◽  
Claudia Bonomo ◽  
Paola Di Bonito ◽  
...  
Keyword(s):  
Human Papillomavirus ◽  
Antitumor Activity ◽  
Tumor Growth ◽  
Tumor Progression ◽  
Cellular Transformation ◽  
Neoplastic Progression ◽  
Single Chain ◽  
Hpv16 E6 ◽  
Associated Lesions ◽  
E6 And E7

Abstract Background The oncogenic activity of the high risk human papillomavirus type 16 (HPV16) is fully dependent on the E6 and E7 viral oncoproteins produced during viral infection. The oncoproteins interfere with cellular homeostasis by promoting proliferation, inhibiting apoptosis and blocking epithelial differentiation, driving the infected cells towards neoplastic progression. The causal relationship between expression of E6/E7 and cellular transformation allows inhibiting the oncogenic process by hindering the activity of the two oncoproteins. We previously developed and characterized some antibodies in single-chain format (scFvs) against the HPV16 E6 and E7 proteins, and demonstrated both in vitro and in vivo their antitumor activity consisting of protective efficacy against tumor progression of HPV16-positive cells. Methods Envisioning clinical application of the best characterized anti-HPV16 E6 and –HPV16 E7 scFvs, we verified their activity in the therapeutic setting, on already implanted tumors. Recombinant plasmids expressing the anti-HPV16 E6 scFvI7 with nuclear targeting sequence, or the anti-HPV16 E7 scFv43M2 with endoplasmic reticulum targeting sequence were delivered by injection followed by electroporation to three different preclinical models using C57/BL6 mice, and their effect on tumor growth was investigated. In the first model, the HPV16+ TC-1 Luc cells were used to implant tumors in mice, and tumor growth was measured by luciferase activity; in the second model, a fourfold number of TC-1 cells was used to obtain more aggressively growing tumors; in the third model, the HPV16+ C3 cells where used to rise tumors in mice. To highlight the scFv possible mechanism of action, H&E and caspase-3 staining of tumor section were performed. Results We showed that both the anti-HPV16 E6 and HPV16 E7 scFvs tested were efficacious in delaying tumor progression in the three experimental models and that their antitumor activity seems to rely on driving tumor cells towards the apoptotic pathway. Conclusion Based on our study, two scFvs have been identified that could represent a safe and effective treatment for the therapy of HPV16-associated lesions. The mechanism underlying the scFv effectiveness appears to be leading cells towards death by apoptosis. Furthermore, the validity of electroporation, a methodology allowed for human treatment, to deliver scFvs to tumors was confirmed.

scholarly journals Loss-of-function mutations in the histone methyltransferase EZH2 promote chemotherapy resistance in AML

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Julia M. Kempf ◽  
Sabrina Weser ◽  
Michael D. Bartoschek ◽  
Klaus H. Metzeler ◽  
Binje Vick ◽  
...  
Keyword(s):  
Target Genes ◽  
Chemotherapeutic Agent ◽  
Chemotherapy Resistance ◽  
Xenograft Model ◽  
Histone Methyltransferase ◽  
Loss Of Function ◽  
Resistance Development ◽  
Selective Growth Advantage ◽  
Patient Derived Xenograft ◽  
Transmembrane Transporter

AbstractChemotherapy resistance is the main impediment in the treatment of acute myeloid leukaemia (AML). Despite rapid advances, the various mechanisms inducing resistance development remain to be defined in detail. Here we report that loss-of-function mutations (LOF) in the histone methyltransferase EZH2 have the potential to confer resistance against the chemotherapeutic agent cytarabine. We identify seven distinct EZH2 mutations leading to loss of H3K27 trimethylation via multiple mechanisms. Analysis of matched diagnosis and relapse samples reveal a heterogenous regulation of EZH2 and a loss of EZH2 in 50% of patients. We confirm that loss of EZH2 induces resistance against cytarabine in the cell lines HEK293T and K562 as well as in a patient-derived xenograft model. Proteomics and transcriptomics analysis reveal that resistance is conferred by upregulation of multiple direct and indirect EZH2 target genes that are involved in apoptosis evasion, augmentation of proliferation and alteration of transmembrane transporter function. Our data indicate that loss of EZH2 results in upregulation of its target genes, providing the cell with a selective growth advantage, which mediates chemotherapy resistance.

scholarly journals ATRT-13. DIFFERENT CELLS OF ORIGIN PAVE THE WAY FOR MOLECULAR HETEROGENEITY IN RHABDOID TUMORS

2020 ◽  
Vol 22 (Supplement_3) ◽  
pp. iii278-iii278
Author(s):  
Monika Graf ◽  
Marta Interlandi ◽  
Natalia Moreno ◽  
Dörthe Holdhof ◽  
Viktoria Melcher ◽  
...  
Keyword(s):  
Single Cell ◽  
Expression Patterns ◽  
Time Frame ◽  
Precursor Cells ◽  
Genetically Engineered ◽  
Molecular Heterogeneity ◽  
Loss Of Function ◽  
Cellular Origin ◽  
Cells Of Origin ◽  
Rhabdoid Tumors

Abstract Rhabdoid tumors (RT) are rare but highly aggressive pediatric neoplasms. These tumors carry homozygous loss-of-function alterations of SMARCB1 in almost all cases with an otherwise low mutational load. RT arise at different intracranial (ATRT) as well as extracranial (MRT) anatomical sites. Three main molecular subgroups (ATRT-SHH, ATRT-TYR, ATRT-MYC) have been characterized for ATRT which are epigenetically and clinically diverse, while MRT show remarkable similarities with ATRT-MYC distinct from ATRT-SHH and ATRT-TYR. Even though there are hypotheses about various cells of origin among RT subgroups, precursor cells of RT have not yet been identified. Previous studies on the temporal control of SMARCB1 knockout in genetically engineered mouse models have unveiled a tight vulnerable time frame during embryogenesis with regard to the susceptibility of precursor cells to result in RT. In this study, we employed single-cell RNA sequencing to describe the intra- and intertumoral heterogeneity of murine ATRT-SHH and -MYC as well as extracranial MYC tumor cells. We defined subgroup-specific tumor markers for all RT classes but also observed a notable overlap of gene expression patterns in all MYC subgroups. By comparing these single-cell transcriptomes with available single-cell maps of early embryogenesis, we gained first insights into the cellular origin of RT. Finally, unsupervised clustering of published human RT methylation data and healthy control tissues confirmed the existence of different cells of origin for intracranial SHH tumors and MYC tumors independent of their anatomical localizations.

scholarly journals Keap1 deletion accelerates mutant K-ras/p53-driven cholangiocarcinoma

2020 ◽  
Vol 318 (3) ◽  
pp. G419-G427 ◽  
Author(s):  
Tatsuhide Nabeshima ◽  
Shin Hamada ◽  
Keiko Taguchi ◽  
Yu Tanaka ◽  
Ryotaro Matsumoto ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Cancer Progression ◽  
Stress Responses ◽  
Target Genes ◽  
Expression Profiles ◽  
Gene Expression Profiles ◽  
Related Factor ◽  
Loss Of Function ◽  
P53 Expression ◽  
Nrf2 Activation

The activation of the Kelch-like ECH-associated protein 1 (Keap1)-NF-E2-related factor 2 (Nrf2) pathway contributes to cancer progression in addition to oxidative stress responses. Loss-of-function Keap1 mutations were reported to activate Nrf2, leading to cancer progression. We examined the effects of Keap1 deletion in a cholangiocarcinoma mouse model using a mutant K-ras/ p53 mouse. Introduction of the Keap1 deletion into liver-specific mutant K-ras/ p53 expression resulted in the formation of invasive cholangiocarcinoma. Comprehensive analyses of the gene expression profiles identified broad upregulation of Nrf2-target genes such as Nqo1 and Gstm1 in the Keap1-deleted mutant K-ras/ p53 expressing livers, accompanied by upregulation of cholangiocyte-related genes. Among these genes, the transcriptional factor Sox9 was highly expressed in the dysplastic bile duct. The Keap-Nrf2-Sox9 axis might serve as a novel therapeutic target for cholangiocarcinoma. NEW & NOTEWORTHY The Keap1-Nrf2 system has a wide variety of effects in addition to the oxidative stress response in cancer cells. Addition of the liver-specific Keap1 deletion to mice harboring mutant K-ras and p53 accelerated cholangiocarcinoma formation, together with the hallmarks of Nrf2 activation. This process involved the expansion of Sox9-positive cells, indicating increased differentiation toward the cholangiocyte phenotype.

C1013G/CXCR4 acts as a driver mutation of tumor progression and modulator of drug resistance in lymphoplasmacytic lymphoma

Blood ◽  
2014 ◽  
Vol 123 (26) ◽  
pp. 4120-4131 ◽  
Author(s):  
Aldo M. Roccaro ◽  
Antonio Sacco ◽  
Cristina Jimenez ◽  
Patricia Maiso ◽  
Michele Moschetta ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Tumor Growth ◽  
Tumor Progression ◽  
Driver Mutation ◽  
Lymphoplasmacytic Lymphoma ◽  
Wild Type ◽  
Key Points ◽  
Activating Mutation

Key Points C1013G/CXCR4 acts as an activating mutation in WM leading to enhanced tumor growth, and as an inducer of drug resistance. BMS936564/MDX1338, a novel anti-CXCR4 moAb, successfully targets WM cells, either C1013G/CXCR4 mutated or wild-type.

scholarly journals DIPG-68. ALPHA-THALASSEMIA X-LINKED MENTAL RETARDATION PROTEIN (ATRX) LOSS-OF-FUNCTION IN A MOUSE MODEL OF DIFFUSE INTRINSIC PONTINE GLIOMA

2020 ◽  
Vol 22 (Supplement_3) ◽  
pp. iii300-iii300
Author(s):  
Chen Shen ◽  
David Picketts ◽  
Oren Becher
Keyword(s):  
Mouse Model ◽  
Pediatric Brain Tumor ◽  
High Grade Glioma ◽  
Genetic Alterations ◽  
Genetically Engineered ◽  
Tumor Incidence ◽  
Loss Of Function ◽  
Nestin Expression ◽  
Genetically Engineered Mouse Model ◽  
Clinical Cases

Abstract Diffuse Intrinsic Potine Glioma (DIPG) is a rare pediatric brain tumor for which no cure or efficacious therapies exist. Previous discoveries have revealed that, DIPG harbors distinct genetic alterations, when compared with adult high-grade glioma (HGG) or even with non-DIPG pediatric HGGs. ATRX alteration is found in 9% of clinical cases of DIPG, and significantly overlaps with H3.3K27M mutation and p53 loss, the two most common genetic changes in DIPG, found in 80% and 77% clinical cases, respectively. Here we developed genetically engineered mouse model of brainstem glioma using the RCAS-Tv-a system by targeting PDGF-B overexpression, p53 loss, H3.3K27M mutation and ATRX loss-of function to Nestin-expression brainstem progenitor cells of the neonatal mouse. Specifically, we used Nestin-Tv-a; p53 floxed; ATRX heterozygous female and Nestin-Tv-a; p53 floxed; ATRX floxed male breeders, generated offsprings with ATRX loss of function (n=18), ATRX heterozygous females (n=6), and ATRX WT (n=10). Median survial of the three groups are 65 days, 88 days and 51 days, respectively. Also, ATRX null mice is lower in tumor incidence (44.4%), compared with ATRX WT (80%). We evaluated the pathological features of DIPG with or without ATRX alteration, RNA-seq is performed to identify differentially expressed genes between ATRX WT and loss-of-function. In conclution, this study generated the first genetically modified mouse model studying ATRX loss-of-function in DIPG, and suggested that ATRX loss-of-function in DIPG may slow down tumorigenesis and decrease tumor incidence.

Sign in / Sign up

Export Citation Format

Share Document