scholarly journals The Novel Phosphatase Domain Mutations Q171R and Y65S Switch PTEN from Tumor Suppressor to Oncogene

Cells ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 3423
Author(s):  
Jose Antonio Ma. G. Garrido ◽  
Krizelle Mae M. Alcantara ◽  
Joshua Miguel C. Danac ◽  
Fidel Emmanuel C. Serrano ◽  
Eva Maria Cutiongco-de la Paz ◽  
...  
Keyword(s):  
Tumor Suppressor ◽  
Protein Function ◽  
Cellular Proliferation ◽  
Morphological Changes ◽  
Structural Constraints ◽  
The Novel ◽  
Phosphatase Domain ◽  
Akt Phosphorylation ◽  
Tensin Homolog ◽  
Downstream Effectors

Phosphatase and tensin homolog deleted on chromosome 10, or PTEN, is a well-characterized tumor suppressor with both lipid and protein phosphatase activities. PTEN is often downregulated by epigenetic mechanisms such as hypermethylation, which leads to constitutive activation of the PI3K–Akt pathway. Large datasets from next-generation sequencing, however, revealed that mutations in PTEN may not only hamper protein function but may also affect interactions with downstream effectors, leading to variable oncogenic readouts. Here, two novel PTEN mutations, Q171R and Y65S, identified in Filipino colorectal cancer patients, were phenotypically characterized in NIH3T3 and HCT116 cells, alongside the C124S canonical mutant and wild-type controls. The novel mutants increased cellular proliferation, resistance to apoptosis and migratory capacity. They induced gross morphological changes including cytoplasmic shrinkage, increased cellular protrusions and extensive cytoskeletal reorganization. The mutants also induced a modest increase in Akt phosphorylation. Further mechanistic studies will help determine the differential oncogenic potencies of these mutants, and resolve whether the structural constraints imposed by the mutations may have altered associations with downstream effectors.

Correlation Between Cellular Functions and Morphological Changes of Human Trophoblast in Vitro

1975 ◽  
Vol 33 ◽  
pp. 600-601
Author(s):  
John C. Garancis ◽  
Robert O. Hussa ◽  
Michael T. Story ◽  
Donald Yorde ◽  
Roland A. Pattillo
Keyword(s):  
Electron Microscopy ◽  
Cellular Proliferation ◽  
Morphological Changes ◽  
Culture Fluid ◽  
Cellular Functions ◽  
Human Trophoblast ◽  
Transmission Electron ◽  
Marked Activity ◽  
Malignant Trophoblast

Human malignant trophoblast cells in continuous culture were incubated for 3 days in medium containing 1 mM N6-O2'-dibutyryl cyclic adenosine 3':5'-monophosphate (dibutyryl cyclic AMP) and 1 mM theophylline. The culture fluid was replenished daily. Stimulated cultures secreted many times more chorionic gonadotropin and estrogens than did control cultures in the absence of increased cellular proliferation. Scanning electron microscopy revealed remarkable surface changes of stimulated cells. Control cells (not stimulated) were smooth or provided with varying numbers of microvilli (Fig. 1). The latter, usually, were short and thin. The surface features of stimulated cells were considerably different. There was marked increase of microvilli which appeared elongated and thick. Many cells were covered with confluent polypoid projections (Fig. 2). Transmission electron microscopy demonstrated marked activity of cytoplasmic organelles. Mitochondria were increased in number and size; some giant forms with numerous cristae were observed.

scholarly journals Combined Application of Pan-AKT Inhibitor MK-2206 and BCL-2 Antagonist Venetoclax in B-Cell Precursor Acute Lymphoblastic Leukemia

2021 ◽  
Vol 22 (5) ◽  
pp. 2771
Author(s):  
Anna Richter ◽  
Elisabeth Fischer ◽  
Clemens Holz ◽  
Julia Schulze ◽  
Sandra Lange ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Tumor Cell ◽  
Cell Lines ◽  
Morphological Changes ◽  
Synergistic Effects ◽  
Lymphoblastic Leukemia ◽  
Tumor Cell Proliferation ◽  
Akt Inhibitor ◽  
Akt Phosphorylation ◽  
Combined Application

Aberrant PI3K/AKT signaling is a hallmark of acute B-lymphoblastic leukemia (B-ALL) resulting in increased tumor cell proliferation and apoptosis deficiency. While previous AKT inhibitors struggled with selectivity, MK-2206 promises meticulous pan-AKT targeting with proven anti-tumor activity. We herein, characterize the effect of MK-2206 on B-ALL cell lines and primary samples and investigate potential synergistic effects with BCL-2 inhibitor venetoclax to overcome limitations in apoptosis induction. MK-2206 incubation reduced AKT phosphorylation and influenced downstream signaling activity. Interestingly, after MK-2206 mono application tumor cell proliferation and metabolic activity were diminished significantly independently of basal AKT phosphorylation. Morphological changes but no induction of apoptosis was detected in the observed cell lines. In contrast, primary samples cultivated in a protective microenvironment showed a decrease in vital cells. Combined MK-2206 and venetoclax incubation resulted in partially synergistic anti-proliferative effects independently of application sequence in SEM and RS4;11 cell lines. Venetoclax-mediated apoptosis was not intensified by addition of MK-2206. Functional assessment of BCL-2 inhibition via Bax translocation assay revealed slightly increased pro-apoptotic signaling after combined MK-2206 and venetoclax incubation. In summary, we demonstrate that the pan-AKT inhibitor MK-2206 potently blocks B-ALL cell proliferation and for the first time characterize the synergistic effect of combined MK-2206 and venetoclax treatment in B-ALL.

scholarly journals Presence of Chromosomal crpP-like Genes Is Not Always Associated with Ciprofloxacin Resistance in Pseudomonas aeruginosa Clinical Isolates Recovered in ICU Patients from Portugal and Spain

2021 ◽  
Vol 9 (2) ◽  
pp. 388
Author(s):  
Marta Hernández-García ◽  
María García-Castillo ◽  
Sergio García-Fernández ◽  
Diego López-Mendoza ◽  
Jazmín Díaz-Regañón ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Protein Function ◽  
Resistance Mechanism ◽  
Amino Acid Position ◽  
Genomic Islands ◽  
Missense Mutations ◽  
The Novel ◽  
Surveillance Studies ◽  
Ciprofloxacin Resistance ◽  
Chromosomal Mutations

CrpP enzymes have been recently described as a novel ciprofloxacin-resistance mechanism. We investigated by whole genome sequencing the presence of crpP-genes and other mechanisms involved in quinolone resistance in MDR/XDR-Pseudomonas aeruginosa isolates (n = 55) with both ceftolozane-tazobactam susceptible or resistant profiles recovered from intensive care unit patients during the STEP (Portugal) and SUPERIOR (Spain) surveillance studies. Ciprofloxacin resistance was associated with mutations in the gyrA and parC genes. Additionally, plasmid-mediated genes (qnrS2 and aac(6′)-Ib-cr) were eventually detected. Ten chromosomal crpP-like genes contained in related pathogenicity genomic islands and 6 different CrpP (CrpP1-CrpP6) proteins were found in 65% (36/55) of the isolates. Dissemination of CrpP variants was observed among non-related clones of both countries, including the CC175 (Spain) high-risk clone and CC348 (Portugal) clone. Interestingly, 5 of 6 variants (CrpP1-CrpP5) carried missense mutations in an amino acid position (Gly7) previously defined as essential conferring ciprofloxacin resistance, and decreased ciprofloxacin susceptibility was only associated with the novel CrpP6 protein. In our collection, ciprofloxacin resistance was mainly due to chromosomal mutations in the gyrA and parC genes. However, crpP genes carrying mutations essential for protein function (G7, I26) and associated with a restored ciprofloxacin susceptibility were predominant. Despite the presence of crpP genes is not always associated with ciprofloxacin resistance, the risk of emergence of novel CrpP variants with a higher ability to affect quinolones is increasing. Furthermore, the spread of crpP genes in highly mobilizable genomic islands among related and non-related P. aeruginosa clones alert the dispersion of MDR pathogens in hospital settings.

scholarly journals Tumor-suppressor function of Beclin 1 in breast cancer cells requires E-cadherin

2021 ◽  
Vol 118 (5) ◽  
pp. e2020478118
Author(s):  
Tobias Wijshake ◽  
Zhongju Zou ◽  
Beibei Chen ◽  
Lin Zhong ◽  
Guanghua Xiao ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Tumor Suppressor ◽  
Cancer Cells ◽  
Breast Cancer Cells ◽  
Target Genes ◽  
Cellular Proliferation ◽  
Beclin 1 ◽  
Beta Catenin ◽  
A Genome ◽  
E Cadherin

Beclin 1, an autophagy and haploinsufficient tumor-suppressor protein, is frequently monoallelically deleted in breast and ovarian cancers. However, the precise mechanisms by which Beclin 1 inhibits tumor growth remain largely unknown. To address this question, we performed a genome-wide CRISPR/Cas9 screen in MCF7 breast cancer cells to identify genes whose loss of function reverse Beclin 1-dependent inhibition of cellular proliferation. Small guide RNAs targeting CDH1 and CTNNA1, tumor-suppressor genes that encode cadherin/catenin complex members E-cadherin and alpha-catenin, respectively, were highly enriched in the screen. CRISPR/Cas9-mediated knockout of CDH1 or CTNNA1 reversed Beclin 1-dependent suppression of breast cancer cell proliferation and anchorage-independent growth. Moreover, deletion of CDH1 or CTNNA1 inhibited the tumor-suppressor effects of Beclin 1 in breast cancer xenografts. Enforced Beclin 1 expression in MCF7 cells and tumor xenografts increased cell surface localization of E-cadherin and decreased expression of mesenchymal markers and beta-catenin/Wnt target genes. Furthermore, CRISPR/Cas9-mediated knockout of BECN1 and the autophagy class III phosphatidylinositol kinase complex 2 (PI3KC3-C2) gene, UVRAG, but not PI3KC3-C1–specific ATG14 or other autophagy genes ATG13, ATG5, or ATG7, resulted in decreased E-cadherin plasma membrane and increased cytoplasmic E-cadherin localization. Taken together, these data reveal previously unrecognized cooperation between Beclin 1 and E-cadherin–mediated tumor suppression in breast cancer cells.

Abstract 183: Small Molecule Gβ? Inhibition Reduces Pathologic Activation of Cardiac Fibroblasts

2013 ◽  
Vol 113 (suppl_1) ◽  
Author(s):  
Joshua G Travers ◽  
Fadia A Kamal ◽  
Burns C Blaxall
Keyword(s):  
Cardiac Hypertrophy ◽  
Small Molecule ◽  
Adrenergic Receptor ◽  
Cellular Proliferation ◽  
Therapeutic Potential ◽  
Cardiac Fibroblasts ◽  
Akt Phosphorylation ◽  
Potential Therapeutic Role ◽  
Protease Activated Receptor 1 ◽  
Chronic Activation

Heart failure (HF) is a devastating disease characterized by cardiac hypertrophy, fibrosis and inflammation. Excess signaling through Gβγ subunits leads to chronic β-adrenergic receptor (β-AR) downregulation, mediated predominantly by GRK2 in complex with PI3Kγ. Our recent work has demonstrated the therapeutic potential of the small molecule Gβγ-GRK2 inhibitor Gallein in limiting HF progression. Chronic activation of cardiac fibroblasts (CF), critical yet underappreciated myocardial cells, is a key contributor to pathologic cardiac remodeling. We hypothesized that Gβγ-GRK2 inhibition may limit pathologic CF activation. CFs were stimulated with Isoproterenol (Iso, β-AR agonist), AngII, or vehicle (V), +/- Gβγ inhibition for 24hr. Gallein treatment attenuated the induction of αSMA expression, a marker of pathologic CF activation, and two inflammatory cytokines, IL-1β and IL-6 in response to these pathologic stimuli (Iso, AngII), as assessed by real time PCR. This data suggest that Gallein treatment may reduce pathologic CF activation. Iso stimulation also enhances the phosphorylation of Akt, a kinase downstream of PI3Kγ known to be involved in cellular proliferation. Gβγ inhibition mitigated this induction, decreasing Akt phosphorylation >60% in response to Iso. This phenomenon was also observed in failing human CFs, in which Gallein decreased Akt phosphorylation >70%. We have recently demonstrated that the protease-activated receptor 1 (PAR1), a GPCR we have implicated in cardiac hypertrophy, is transactivated via chronic β-AR stimulation by induction of MMP-13, a protease we have found to be elevated in HF. Recent data from our lab and others have demonstrated that PAR1 is the most abundantly expressed GPCR in CFs, and that its stimulation in CFs may be pathologic. Interestingly, Gβγ inhibition treatment reduced PAR1 cleavage and activation in response to chronic Iso. In summary, small molecule Gβγ inhibition appears to reduce pathologic CF activation. The reduction in β-AR-mediated PAR1 cleavage reveals an alternative role for Gβγ inhibition in preventing CF activation and proliferation. These data suggest a potential therapeutic role for small molecule Gβγ inhibition in limiting pathologic CF activation and cardiac hypertrophy.

Epigenetic Silencing of Tumor Suppressor lncRNA NKILA: Implication on NF-κB Signaling in Non-Hodgkin’s Lymphoma

2020 ◽  
Author(s):  
Min Yue Zhang ◽  
Ming Dan Deng ◽  
Lu Qian Wang ◽  
Rex K.H. Au-Yeung ◽  
Chor Sang Chim
Keyword(s):  
Dna Methylation ◽  
Cell Death ◽  
Tumor Suppressor ◽  
Hodgkin’S Lymphoma ◽  
Cellular Proliferation ◽  
Cell Lymphoma ◽  
Hodgkin's Lymphoma ◽  
Non Hodgkin's Lymphoma ◽  
Promoter Dna Methylation ◽  
Promoter Dna

Abstract Background: NKILA, localized to 20q13.31, is a negative regulator of NF-κB signaling implicated in carcinogenesis. As a CpG island is embedded in the promoter region of NKILA, we hypothesized that NKILA is a tumor suppressor lncRNA reversibly silenced by promoter DNA methylation in non-Hodgkin’s lymphoma (NHL). Results: By pyrosequencing-verified methylation-specific PCR (MSP), NKILA was unmethylated in normal healthy controls, including 10 peripheral blood buffy coats and 11 normal tonsils tissue, but completely methylated in one (10%) NHL cell line SU-DHL-6. Among the lymphoma cell lines, by semi-quantitative RT-PCR, methylation of NKILA was inversely correlated with its expression. In the completely methylated SU-DHL-6 cells, hypomethylation treatment with 5-Aza-2'-deoxycytidine resulted in promoter demethylation and re-expression of NKILA transcript. In NHL primary samples (n=102), NKILA methylation was observed none of mantle cell lymphoma (MCL) cases, but in 29 (51.79%) diffuse large-B cell lymphoma (DLBCL) and 4 (20%) peripheral T-cell lymphoma (PTCL) cases, hence preferentially methylated in DLBCL than MCL (P < 0.0001) and PTCL (P = 0.007). Mechanistically, knockdown of NKILA resulted in promoting IkBα phosphorylation, which was associated with nucleus translocation of total p65 and phosphorylated p65 in SU-DHL-1 cells, hence constitutive NF-κB activation. Functionally, knock-down of NKILA in SU-DHL-1 cells led to decreased cell death and increased cellular proliferation, indicating a tumor suppressor role of NKILA in NHL cells. Conclusions: NKILA was a tumour suppressor lncRNA frequently hypermethylated in DLBCL. Promoter DNA methylation-mediated NKILA silencing led to increase of cellular proliferation and decrease of cell death via repression of NF-κB signaling in NHL cells.

scholarly journals Transcriptional Regulation of Genes by Ikaros Tumor Suppressor in Acute Lymphoblastic Leukemia

2020 ◽  
Vol 21 (4) ◽  
pp. 1377
Author(s):  
Pavan Kumar Dhanyamraju ◽  
Soumya Iyer ◽  
Gayle Smink ◽  
Yevgeniya Bamme ◽  
Preeti Bhadauria ◽  
...  
Keyword(s):  
Acute Lymphoblastic Leukemia ◽  
Tumor Suppressor ◽  
Chromatin Remodeling ◽  
Target Genes ◽  
Cellular Proliferation ◽  
Lymphoblastic Leukemia ◽  
Regulatory Elements ◽  
Binding Motif ◽  
Functional Inactivation

Regulation of oncogenic gene expression by transcription factors that function as tumor suppressors is one of the major mechanisms that regulate leukemogenesis. Understanding this complex process is essential for explaining the pathogenesis of leukemia as well as developing targeted therapies. Here, we provide an overview of the role of Ikaros tumor suppressor and its role in regulation of gene transcription in acute leukemia. Ikaros (IKZF1) is a DNA-binding protein that functions as a master regulator of hematopoiesis and the immune system, as well as a tumor suppressor in acute lymphoblastic leukemia (ALL). Genetic alteration or functional inactivation of Ikaros results in the development of high-risk leukemia. Ikaros binds to the specific consensus binding motif at upstream regulatory elements of its target genes, recruits chromatin-remodeling complexes and activates or represses transcription via chromatin remodeling. Over the last twenty years, a large number of Ikaros target genes have been identified, and the role of Ikaros in the regulation of their expression provided insight into the mechanisms of Ikaros tumor suppressor function in leukemia. Here we summarize the role of Ikaros in the regulation of the expression of the genes whose function is critical for cellular proliferation, development, and progression of acute lymphoblastic leukemia.

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.

Sign in / Sign up

Export Citation Format

Share Document