scholarly journals Genomic loss of the putative tumor suppressor gene E2A in human lymphoma

2011 ◽  
Vol 208 (8) ◽  
pp. 1585-1593 ◽  
Author(s):  
Anne Steininger ◽  
Markus Möbs ◽  
Reinhard Ullmann ◽  
Karl Köchert ◽  
Stephan Kreher ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Tumor Suppressor ◽  
Cell Cycle Progression ◽  
Treatment Strategies ◽  
Suppressor Gene ◽  
Lymphoid Cells ◽  
Oncogenic Signaling ◽  
Putative Tumor Suppressor Gene ◽  
Ras Pathway ◽  
New Treatment

The transcription factor E2A is essential for lymphocyte development. In this study, we describe a recurrent E2A gene deletion in at least 70% of patients with Sézary syndrome (SS), a subtype of T cell lymphoma. Loss of E2A results in enhanced proliferation and cell cycle progression via derepression of the protooncogene MYC and the cell cycle regulator CDK6. Furthermore, by examining the gene expression profile of SS cells after restoration of E2A expression, we identify several E2A-regulated genes that interfere with oncogenic signaling pathways, including the Ras pathway. Several of these genes are down-regulated or lost in primary SS tumor cells. These data demonstrate a tumor suppressor function of E2A in human lymphoid cells and could help to develop new treatment strategies for human lymphomas with altered E2A activity.

scholarly journals The PTEN Tumor Suppressor Gene in Soft Tissue Sarcoma

Cancers ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1169 ◽  
Author(s):  
Sioletic Stefano ◽  
Scambia Giovanni
Keyword(s):  
Soft Tissue ◽  
Tumor Suppressor ◽  
Soft Tissue Sarcoma ◽  
Biological Significance ◽  
Treatment Strategies ◽  
Predictive Biomarkers ◽  
Suppressor Gene ◽  
Oncogenic Signaling ◽  
Tensin Homolog ◽  
Pathologic Features

Soft tissue sarcoma (STS) is a rare malignancy of mesenchymal origin classified into more than 50 different subtypes with distinct clinical and pathologic features. Despite the poor prognosis in the majority of patients, only modest improvements in treatment strategies have been achieved, largely due to the rarity and heterogeneity of these tumors. Therefore, the discovery of new prognostic and predictive biomarkers, together with new therapeutic targets, is of enormous interest. Phosphatase and tensin homolog (PTEN) is a well-known tumor suppressor that commonly loses its function via mutation, deletion, transcriptional silencing, or protein instability, and is frequently downregulated in distinct sarcoma subtypes. The loss of PTEN function has consequent alterations in important pathways implicated in cell proliferation, survival, migration, and genomic stability. PTEN can also interact with other tumor suppressors and oncogenic signaling pathways that have important implications for the pathogenesis in certain STSs. The aim of the present review is to summarize the biological significance of PTEN in STS and its potential role in the development of new therapeutic strategies.

scholarly journals The NF2 Tumor Suppressor Gene Product, Merlin, Inhibits Cell Proliferation and Cell Cycle Progression by Repressing Cyclin D1 Expression

2005 ◽  
Vol 25 (6) ◽  
pp. 2384-2394 ◽  
Author(s):  
Guang-Hui Xiao ◽  
Ryan Gallagher ◽  
Justin Shetler ◽  
Kristine Skele ◽  
Deborah A. Altomare ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Tumor Suppressor ◽  
Cyclin D1 ◽  
Tumor Suppressor Gene ◽  
Promoter Activity ◽  
Cell Cycle Progression ◽  
Malignant Tumors ◽  
Suppressor Gene ◽  
Cycle Progression

ABSTRACT Inactivation of the NF2 tumor suppressor gene has been observed in certain benign and malignant tumors. Recent studies have demonstrated that merlin, the product of the NF2 gene, is regulated by Rac/PAK signaling. However, the mechanism by which merlin acts as a tumor suppressor has remained obscure. In this report, we show that adenovirus-mediated expression of merlin in NF2-deficient tumor cells inhibits cell proliferation and arrests cells at G1 phase, concomitant with decreased expression of cyclin D1, inhibition of CDK4 activity, and dephosphorylation of pRB. The effect of merlin on cell cycle progression was partially overridden by ectopic expression of cyclin D1. RNA interference experiments showed that silencing of the endogenous NF2 gene results in upregulation of cyclin D1 and S-phase entry. Furthermore, PAK1-stimulated cyclin D1 promoter activity was repressed by cotransfection of NF2, and PAK activity was inhibited by expression of merlin. Interestingly, the S518A mutant form of merlin, which is refractory to phosphorylation by PAK, was more efficient than the wild-type protein in inhibiting cell cycle progression and in repressing cyclin D1 promoter activity. Collectively, our data indicate that merlin exerts its antiproliferative effect, at least in part, via repression of PAK-induced cyclin D1 expression, suggesting a unifying mechanism by which merlin inactivation might contribute to the overgrowth seen in both noninvasive and malignant tumors.

ID3 Is a Novel Tumor Suppressor Gene in Burkitt Lymphom

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 898-898
Author(s):  
Cassandra L Love ◽  
Dereje Jima ◽  
Zhen Sun ◽  
Rodney R. Miles ◽  
Cherie H. Dunphy ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
Tumor Suppressor ◽  
Burkitt Lymphoma ◽  
Cell Cycle Progression ◽  
Suppressor Gene ◽  
S Phase ◽  
Wild Type ◽  
Cycle Progression ◽  
Helix Loop Helix

Abstract Abstract 898 Burkitt Lymphoma (BL) is a highly proliferative form of non-Hodgkin lymphoma and is characterized by translocation of the C-MYC gene to the immunoglobulin gene loci resulting in deregulation. The role of collaborating gene mutations in BL is largely unknown. We performed whole exome sequencing and gene expression profiling of 57 Burkitt lymphoma and 94 DLBCL exomes. Mutational analysis revealed that ID3 is recurrently mutated in 38% of Burkitt lymphoma samples. ID3 mutations did not occur in any of the 94 DLBCL cases. ID3 gene expression was also found to be a distinguishing feature of Burkitt lymphomas (P<10−6), compared to DLBCL. We found a total of 27 distinct mutations in the ID3 genes among the 22 BL cases. These included five frameshift, four nonsense, and 18 missense mutations. We validated 16 of these events with Sanger sequencing with over 90% concordance. All of these mutations were located in the highly conserved helix-loop-helix region located on Exon 1. We explored the biological significance of ID3 mutations by initially comparing the gene expression profiles of BL cases that had mutated and wild-type ID3. Gene set enrichment analysis showed that those samples with mutated ID3 had higher expression of genes that were involved in cell cycle regulation, specifically those involved in the G1-S transition (P=0.01). In order to experimentally investigate the functional consequences of ID3 mutation, we generated mutant constructs corresponding to six different ID3 mutations observed in BLs. These mutant constructs were cloned into lentiviral vectors and overexpressed in BL cells that were wild type for ID3. We then performed cell cycle analysis for these wild type cells expressing GFP controls or the mutant constructs. We found that BL cells expressing each of the six mutant constructs demonstrated significant cell cycle progression from G1 to S phase compared to wild-type (P=0.01). Separately, we tested the effects of expressing mutant ID3 in cell proliferation assays and found that cells expressing mutant ID3 were considerably more proliferative than those expressing wild type (P=0.03). Conversely, we over-expressed the wild type form of ID3 in BL cells that had mutated ID3. These experiments completely rescued the observed phenotypes of the mutant ID3 constructs, with reduced cell cycle progression through increased G1 phase and decreased S-phase (P=0.04). We also noted decreased cell proliferation in these cells (P=0.03). These experiments support a role for ID3 as a novel tumor suppressor gene in Burkitt lymphoma. ID3 is a basic helix loop helix (bHLH) protein that binds to other E-proteins, blocking their ability to bind DNA. ID3 has been shown to be involved in a variety of biological processes including development and T and B cell differentiation. ID3 knockout mice have been shown to develop T cell as well as B cell lymphomas. Our data implicates this gene for the first time as a tumor suppressor in human cancer. Disclosures: No relevant conflicts of interest to declare.

scholarly journals TP53 PATHOGENIC VARIANTS RELATED TO CANCER

2019 ◽  
Vol 30 (2) ◽  
pp. 27-40
Author(s):  
C.Y. Rosero ◽  
L.G. Mejia ◽  
M. Corredor
Keyword(s):  
Cell Cycle ◽  
Tumor Suppressor ◽  
Suppressor Gene ◽  
Lymphoid Cells ◽  
Reading Frame ◽  
Synonymous Mutations ◽  
Pathogenic Variants ◽  
Repair Enzymes ◽  
Self Sufficiency ◽  
And Function

TP53 or P53 is a tumor suppressor gene known as the “genome guardian”, responsible for inducing cell response to DNA damage, by stopping the cell cycle in case of mutation, activating DNA repair enzymes, initiating senescence and activation of apoptosis. Mutations in the gene sequence can cause non-synonymous mutations or errors in the reading frame by insertion, deletion or displacement of nucleotides: e.g., c.358A>G mutation in exon 4 and variants located in exons 9 and 10 of the TD domain. Therefore, in this review, we will see that changes in the reading frame, including the loss of one or two base pairs could prevent accurate transcription or changes in the structure and function of the protein, and could completely impair reparation function. These changes promote self-sufficiency in growth signaling, insensitivity to anti-growth signals, and evasion of apoptosis, resulting in limitless replication and induction of metastatic angiogenesis, generating as a consequence the proliferation of tumor, neoplastic, and lymphoid cells. Taking into account the importance of TP53 in the regulation of the cell cycle, the objective of this review is to update information related to the role of this gene in the development of cancer and the description of genetic variations. Key words: Neoplasms, nuclear phosphoprotein p53, Tumor Suppressor, mutation, Clinvar, Uniprot

scholarly journals E2F and its developmental regulation in Xenopus laevis.

1994 ◽  
Vol 14 (7) ◽  
pp. 5000-5009 ◽  
Author(s):  
A Philpott ◽  
S H Friend
Keyword(s):  
Cell Cycle ◽  
Tumor Suppressor ◽  
Xenopus Laevis ◽  
Tumor Suppressor Gene ◽  
Cell Cycle Progression ◽  
Suppressor Gene ◽  
Embryonic Cell ◽  
Free Form ◽  
Gene Products ◽  
Cyclin Dependent Kinases

The transcription factor E2F has been implicated in cell cycle control by virtue of its association with cyclins, cyclin-dependent kinases, and pRb-related tumor suppressor gene products. Eggs and embryos from the frog Xenopus laevis have been used to investigate the characteristics of E2F-like molecules in the Xenopus cell cycle and throughout early development. We find multiple E2F species in Xenopus eggs, at least one of which is modified by phosphorylation. The vast majority of E2F remains in the free form throughout the very early embryonic cell cycle, and it also remains predominantly free until some time after the mid-blastula transition, the onset of zygotic transcription. At this time, E2F complexes significantly to pRb but not to cdk2, although cdk2 binding is found in tissue culture cells from a very advanced stage in embryogenesis. This suggests that the complexing of E2F to cyclins, cyclin-dependent kinases, and tumor suppressor gene products may be controlled separately in early Xenopus development. Thus, the association of E2F with other molecules may not result solely from processes affecting cell cycle progression but may also reflect developmental and differentiation cues.

E2F and its developmental regulation in Xenopus laevis

1994 ◽  
Vol 14 (7) ◽  
pp. 5000-5009
Author(s):  
A Philpott ◽  
S H Friend
Keyword(s):  
Cell Cycle ◽  
Tumor Suppressor ◽  
Xenopus Laevis ◽  
Tumor Suppressor Gene ◽  
Cell Cycle Progression ◽  
Suppressor Gene ◽  
Embryonic Cell ◽  
Free Form ◽  
Gene Products ◽  
Cyclin Dependent Kinases

The transcription factor E2F has been implicated in cell cycle control by virtue of its association with cyclins, cyclin-dependent kinases, and pRb-related tumor suppressor gene products. Eggs and embryos from the frog Xenopus laevis have been used to investigate the characteristics of E2F-like molecules in the Xenopus cell cycle and throughout early development. We find multiple E2F species in Xenopus eggs, at least one of which is modified by phosphorylation. The vast majority of E2F remains in the free form throughout the very early embryonic cell cycle, and it also remains predominantly free until some time after the mid-blastula transition, the onset of zygotic transcription. At this time, E2F complexes significantly to pRb but not to cdk2, although cdk2 binding is found in tissue culture cells from a very advanced stage in embryogenesis. This suggests that the complexing of E2F to cyclins, cyclin-dependent kinases, and tumor suppressor gene products may be controlled separately in early Xenopus development. Thus, the association of E2F with other molecules may not result solely from processes affecting cell cycle progression but may also reflect developmental and differentiation cues.

Neuroradiology Manifestations of Li-Fraumeni Syndrome: Epidemiology, Genetics, Imaging Findings, and Management

Neurographics ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 228-235
Author(s):  
S. Naganawa ◽  
T. Donohue ◽  
A. Capizzano ◽  
Y. Ota ◽  
J. Kim ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Tumor Suppressor ◽  
Tumor Suppressor Gene ◽  
Soft Tissue Sarcomas ◽  
Suppressor Gene ◽  
Imaging Findings ◽  
Li Fraumeni Syndrome ◽  
Increased Risk ◽  
Li Fraumeni ◽  
Risk Of Cancer

Li-Fraumeni syndrome is a familial cancer predisposition syndrome associated with germline mutation of the tumor suppressor gene 53, which encodes the tumor suppressor p53 protein. Affected patients are predisposed to an increased risk of cancer development, including soft-tissue sarcomas, breast cancer, brain tumors, and adrenocortical carcinoma, among other malignancies. The tumor suppressor gene TP53 plays an important, complex role in regulating the cell cycle, collaborating with transcription factors and other proteins. The disruption of appropriate cell cycle regulation by mutated TP53 is considered to be the cause of tumorigenesis in Li-Fraumeni syndrome. Appropriate surveillance, predominantly by using MR imaging, is used for early malignancy screening in an effort to improve the survival rate among individuals who are affected. Patients with Li-Fraumeni syndrome are also at increased risk for neoplasm development after radiation exposure, and, therefore, avoiding unnecessary radiation in both the diagnostic and therapeutic settings is paramount. Here, we review the epidemiology, genetics, imaging findings, and the current standard surveillance protocol for Li-Fraumeni syndrome from the National Comprehensive Cancer Network as well as potential treatment options.Learning Objective: Describe the cause of second primary malignancy among patients with Li-Fraumeni syndrome.

scholarly journals The Olive Leaves Extract Has Anti-Tumor Effects against Neuroblastoma through Inhibition of Cell Proliferation and Induction of Apoptosis

Nutrients ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 2178
Author(s):  
Fabio Morandi ◽  
Veronica Bensa ◽  
Enzo Calarco ◽  
Fabio Pastorino ◽  
Patrizia Perri ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Cell Viability ◽  
Cell Cycle Progression ◽  
Treatment Strategies ◽  
Annexin V ◽  
Dependent Manner ◽  
Induction Of Apoptosis ◽  
Dose Dependent

Neuroblastoma (NB) is the most common extra-cranial solid tumor of pediatric age. The prognosis for high-risk NB patients remains poor, and new treatment strategies are desirable. The olive leaf extract (OLE) is constituted by phenolic compounds, whose health beneficial effects were reported. Here, the anti-tumor effects of OLE were investigated in vitro on a panel of NB cell lines in terms of (i) reduction of cell viability; (ii) inhibition of cell proliferation through cell cycle arrest; (iii) induction of apoptosis; and (iv) inhibition of cell migration. Furthermore, cytotoxicity experiments, by combining OLE with the chemotherapeutic topotecan, were also performed. OLE reduced the cell viability of NB cells in a time- and dose-dependent manner in 2D and 3D models. NB cells exposed to OLE underwent inhibition of cell proliferation, which was characterized by an arrest of the cell cycle progression in G0/G1 phase and by the accumulation of cells in the sub-G0 phase, which is peculiar of apoptotic death. This was confirmed by a dose-dependent increase of Annexin V+ cells (peculiar of apoptosis) and upregulation of caspases 3 and 7 protein levels. Moreover, OLE inhibited the migration of NB cells. Finally, the anti-tumor efficacy of the chemotherapeutic topotecan, in terms of cell viability reduction, was greatly enhanced by its combination with OLE. In conclusion, OLE has anti-tumor activity against NB by inhibiting cell proliferation and migration and by inducing apoptosis.

scholarly journals GIPC2 is an endocrine-specific tumor suppressor gene for both sporadic and hereditary tumors of RET- and SDHB-, but not VHL-associated clusters of pheochromocytoma/paraganglioma

2021 ◽  
Vol 12 (5) ◽  
Author(s):  
Yeqing Dong ◽  
Yongsheng Huang ◽  
Chengyan Fan ◽  
Liang Wang ◽  
Ran Zhang ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Tumor Suppressor ◽  
Tumor Suppressor Gene ◽  
Chromaffin Cells ◽  
Disease Free Survival ◽  
Suppressor Gene ◽  
Adrenal Chromaffin Cell ◽  
Putative Tumor Suppressor Gene ◽  
Mutant Effect ◽  
Hereditary Tumors

AbstractPheochromocytoma/paraganglioma (PPGL) is an endocrine tumor of the chromaffin cells in the adrenal medulla or the paraganglia. Currently, about 70% of PPGLs can be explained by germline or somatic mutations in several broadly expressed susceptibility genes including RET, VHL, and SDHB, while for the remaining, mainly sporadic cases, the pathogenesis is still unclear. Even for known susceptible genes, how mutations in these mostly ubiquitous genes result in tissue-specific pathogenesis remains unanswered, and why RET-mutated tumors almost always occur in the adrenal while SDHB-mutated tumors mostly occur extra-adrenal remains a mystery. By analyzing 22 sporadic PPGLs using SNP 6.0 genotyping arrays combined with expression profiling of 4 normal and 4 tumor tissues, we identified GIPC2, a gene located at 1p31.1 with preferential expression in adrenal and inducible by adrenal glucocorticoid, as a novel putative tumor suppressor gene for PPGLs. Copy number deletion and GIPC2 promoter hypermethylation but not GIPC2 mutation, accompanied with reduced GIPC2 expression, were observed in 39 of 55 PPGLs in our cohort. Examination of a published expression database consisting of 188 PPGLs found little GIPC2 expression in Cluster 1A (SDHx-associated) and Cluster 2A (NF1/RET-associated) tumors, but less pronounced reduction of GIPC2 expression in Cluster 1B (VHL-associated) and Cluster 2B/2C tumors. GIPC2 induced p27, suppressed MAPK/ERK and HIF-1ɑ pathways as well as cancer cell proliferation. Overexpressing GIPC2 in PC12 cells inhibited tumor growth in nude mice. We found GIPC2 interacted with the nucleoprotein NONO and both proteins regulated p27 transcription through the same GGCC box on p27 promoter. Significantly, low expression of both GIPC2 and p27 was associated with shorter disease-free survival time of PPGLs patients in the TCGA database. We found that PPGL-causing mutations in RET and in SDHB could lead to primary rat adrenal chromaffin cell proliferation, ERK activation, and p27 downregulation, all requiring downregulating GIPC2. Notably, the RET-mutant effect required the presence of dexamethasone while the SDHB-mutant effect required its absence, providing a plausible explanation for the tumor location preference. In contrast, the PPGL-predisposing VHL mutations had no effect on proliferation and GIPC2 expression but caused p53 downregulation and reduced apoptosis in chromaffin cells compared with wild-type VHL. Thus, our study raises the importance of cortical hormone in PPGL development, and GIPC2 as a novel tumor suppressor provides a unified molecular mechanism for the tumorigenesis of both sporadic and hereditary tumors of Clusters 1A and 2A concerning SDHB and RET, but not tumors of Cluster 1B concerning VHL and other clusters.

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