scholarly journals KRIBB11 Induces Apoptosis in A172 Glioblastoma Cells via MULE-Dependent Degradation of MCL-1

Molecules ◽  
2021 ◽  
Vol 26 (14) ◽  
pp. 4165
Author(s):  
Kyunghyun Yoo ◽  
Hye-Hyeon Yun ◽  
Soon-Young Jung ◽  
Jeong-Hwa Lee
Keyword(s):  
Ubiquitin Ligase ◽  
Therapeutic Strategy ◽  
Anticancer Agent ◽  
Molecular Level ◽  
Constitutive Activity ◽  
Glioblastoma Cells ◽  
Essential Step ◽  
Apoptotic Protein ◽  
Induction Of Apoptosis ◽  
A172 Glioma Cells

KRIBB11, an HSF1 inhibitor, was shown to sensitize various types of cancer cells to treatment with several anticancer drugs. However, the exclusive effects of KRIBB11 in preventing the growth of glioblastoma cells and the related mechanisms have not been elucidated yet. Herein, we aimed to examine the potential of KRIBB11 as an anticancer agent for glioblastoma. Using MTT and colony formation assays and Western blotting for c-PARP, we demonstrated that KRIBB11 substantially inhibits the growth of A172 glioma cells by inducing apoptosis. At the molecular level, KRIBB11 decreased anti-apoptotic protein MCL-1 levels, which was attributable to the increase in MULE ubiquitin ligase levels. However, the constitutive activity of HSF1 in A172 cells was not influenced by the exclusive treatment with KRIBB11. Additionally, based on cycloheximide chase assay, we found that KRIBB11 markedly retarded the degradation of MULE. In conclusion, stabilization of MULE upon KRIBB11 treatment is apparently an essential step for degradation of MCL-1 and the subsequent induction of apoptosis in A172 cells. Our results have expanded the knowledge on molecular pathways controlled by KRIBB11 and could be potentially effective for developing an inhibitory therapeutic strategy for glioblastoma.

Novel players fine-tune plant trade-offs

2015 ◽  
Vol 58 ◽  
pp. 83-100 ◽  
Author(s):  
Selena Gimenez-Ibanez ◽  
Marta Boter ◽  
Roberto Solano
Keyword(s):  
Ubiquitin Ligase ◽  
Feedback Loop ◽  
Molecular Level ◽  
26S Proteasome ◽  
Signalling Molecules ◽  
Transcriptional Reprogramming ◽  
Trade Offs ◽  
Jaz Proteins ◽  
Regulatory Feedback Loop ◽  
Fine Tune

Jasmonates (JAs) are essential signalling molecules that co-ordinate the plant response to biotic and abiotic challenges, as well as co-ordinating several developmental processes. Huge progress has been made over the last decade in understanding the components and mechanisms that govern JA perception and signalling. The bioactive form of the hormone, (+)-7-iso-jasmonyl-l-isoleucine (JA-Ile), is perceived by the COI1–JAZ co-receptor complex. JASMONATE ZIM DOMAIN (JAZ) proteins also act as direct repressors of transcriptional activators such as MYC2. In the emerging picture of JA-Ile perception and signalling, COI1 operates as an E3 ubiquitin ligase that upon binding of JA-Ile targets JAZ repressors for degradation by the 26S proteasome, thereby derepressing transcription factors such as MYC2, which in turn activate JA-Ile-dependent transcriptional reprogramming. It is noteworthy that MYCs and different spliced variants of the JAZ proteins are involved in a negative regulatory feedback loop, which suggests a model that rapidly turns the transcriptional JA-Ile responses on and off and thereby avoids a detrimental overactivation of the pathway. This chapter highlights the most recent advances in our understanding of JA-Ile signalling, focusing on the latest repertoire of new targets of JAZ proteins to control different sets of JA-Ile-mediated responses, novel mechanisms of negative regulation of JA-Ile signalling, and hormonal cross-talk at the molecular level that ultimately determines plant adaptability and survival.

MicroRNA-520c-3p Modulates Doxorubicin-Chemosensitivity in HepG2 Cells

2020 ◽  
Vol 21 (2) ◽  
pp. 237-245 ◽  
Author(s):  
Mohamed A. Ragheb ◽  
Marwa H. Soliman ◽  
Emad M. Elzayat ◽  
Mervat S. Mohamed ◽  
Nada El-Ekiaby ◽  
...  
Keyword(s):  
Hepg2 Cells ◽  
Therapeutic Strategy ◽  
Suppressive Effect ◽  
Expression Level ◽  
Tumor Suppressor Function ◽  
Protein Expression Level ◽  
Blot Technique ◽  
Induction Of Apoptosis ◽  
The Impact

Background: Doxorubicin (DOX) is the most common drugs used in cancer therapy, including Hepatocellular Carcinoma (HCC). Drug resistance, is one of chemotherapy’s significant problems. Emerging studies have shown that microRNAs (miRNAs) could participate in regulating this mechanism. Nevertheless, the impact of miRNAs on HCC chemoresistance is still enigmatic. Objective: Investigating the role of miR-520c-3p in enhancement of anti-tumor effect of DOX against HepG2 cells. Methods: Expression profile for liver related miRNAs (384 miRNAs) has been analyzed on HepG2 cells treated with DOX using qRT-PCR. miR-520c-3p, the most deregulated miRNA, was selected for combination treatment with DOX. Expression level for LEF1, CDK2, CDH1, VIM, Mcl-1 and TP53 was evaluated in miR-520c-3p transfected cells. Cell viability, colony formation, wound healing as well as apoptosis assays have been demonstrated. Furthermore, Mcl-1 protein level was measured using western blot technique. Results: The present data indicated that miR-520c-3p overexpression could render HepG2 cells chemo-sensitive to DOX through enhancing its suppressive effects on proliferation, migration, and induction of apoptosis. The suppressive effect of miR-520c-3p involved altering the expression levels of some key regulators of cell cycle, proliferation, migration and apoptosis including LEF1, CDK2, CDH1, VIM, Mcl-1 and TP53. Interestingly, Mcl-1 was found to be one of the potential targets of miR-520c-3p, and its protein expression level was down-regulated upon miR-520c-3p overexpression. Conclusion: Our data referred to the tumor suppressor function of miR-520c-3p that could modulate chemosensitivity of HepG2 cells toward DOX treatment, providing a promising therapeutic strategy in HCC.

scholarly journals EGFRvIII Promotes Cell Survival during Endoplasmic Reticulum Stress through a Reticulocalbin 1-Dependent Mechanism

Cancers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 1198
Author(s):  
Juliana Gomez ◽  
Zammam Areeb ◽  
Sarah F. Stuart ◽  
Hong P. T. Nguyen ◽  
Lucia Paradiso ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Viability ◽  
Er Stress ◽  
Cell Survival ◽  
Glioblastoma Cells ◽  
Over Expression ◽  
Stress Markers ◽  
Apoptotic Protein ◽  
Novel Association ◽  
Reduced Activity

Reticulocalbin 1 (RCN1) is an endoplasmic reticulum (ER)-residing protein, involved in promoting cell survival during pathophysiological conditions that lead to ER stress. However, the key upstream receptor tyrosine kinase that regulates RCN1 expression and its potential role in cell survival in the glioblastoma setting have not been determined. Here, we demonstrate that RCN1 expression significantly correlates with poor glioblastoma patient survival. We also demonstrate that glioblastoma cells with expression of EGFRvIII receptor also have high RCN1 expression. Over-expression of wildtype EGFR also correlated with high RCN1 expression, suggesting that EGFR and EGFRvIII regulate RCN1 expression. Importantly, cells that expressed EGFRvIII and subsequently showed high RCN1 expression displayed greater cell viability under ER stress compared to EGFRvIII negative glioblastoma cells. Consistently, we also demonstrated that RCN1 knockdown reduced cell viability and exogenous introduction of RCN1 enhanced cell viability following induction of ER stress. Mechanistically, we demonstrate that the EGFRvIII-RCN1-driven increase in cell survival is due to the inactivation of the ER stress markers ATF4 and ATF6, maintained expression of the anti-apoptotic protein Bcl-2 and reduced activity of caspase 3/7. Our current findings identify that EGFRvIII regulates RCN1 expression and that this novel association promotes cell survival in glioblastoma cells during ER stress.

scholarly journals Global phosphoproteomics reveals DYRK1A regulates CDK1 activity in glioblastoma cells

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Ariadna Recasens ◽  
Sean J. Humphrey ◽  
Michael Ellis ◽  
Monira Hoque ◽  
Ramzi H. Abbassi ◽  
...  
Keyword(s):  
Ubiquitin Ligase ◽  
Cyclin B ◽  
Anaphase Promoting Complex ◽  
Mechanistic Studies ◽  
Glioblastoma Cells ◽  
Cycle Arrest ◽  
Dual Specificity ◽  
Rb Pathway ◽  
High Doses

AbstractBoth tumour suppressive and oncogenic functions have been reported for dual-specificity tyrosine phosphorylation-regulated kinase 1A (DYRK1A). Herein, we performed a detailed investigation to delineate the role of DYRK1A in glioblastoma. Our phosphoproteomic and mechanistic studies show that DYRK1A induces degradation of cyclin B by phosphorylating CDC23, which is necessary for the function of the anaphase-promoting complex, a ubiquitin ligase that degrades mitotic proteins. DYRK1A inhibition leads to the accumulation of cyclin B and activation of CDK1. Importantly, we established that the phenotypic response of glioblastoma cells to DYRK1A inhibition depends on both retinoblastoma (RB) expression and the degree of residual DYRK1A activity. Moderate DYRK1A inhibition leads to moderate cyclin B accumulation, CDK1 activation and increased proliferation in RB-deficient cells. In RB-proficient cells, cyclin B/CDK1 activation in response to DYRK1A inhibition is neutralized by the RB pathway, resulting in an unchanged proliferation rate. In contrast, complete DYRK1A inhibition with high doses of inhibitors results in massive cyclin B accumulation, saturation of CDK1 activity and cell cycle arrest, regardless of RB status. These findings provide new insights into the complexity of context-dependent DYRK1A signalling in cancer cells.

scholarly journals Transition of yeast Can1 transporter to the inward-facing state unveils an α-arrestin target sequence promoting its ubiquitylation and endocytosis

2017 ◽  
Vol 28 (21) ◽  
pp. 2819-2832 ◽  
Author(s):  
Christos Gournas ◽  
Elie Saliba ◽  
Eva-Maria Krammer ◽  
Céline Barthelemy ◽  
Martine Prévost ◽  
...  
Keyword(s):  
Ubiquitin Ligase ◽  
Control Mechanism ◽  
Molecular Level ◽  
Membrane Transporters ◽  
Signaling Cascades ◽  
Target Sequence ◽  
Target Region ◽  
Substrate Transport ◽  
Common Control ◽  
Amino Acid Permeases

Substrate-transport–elicited endocytosis is a common control mechanism of membrane transporters avoiding excess uptake of external compounds, though poorly understood at the molecular level. In yeast, endocytosis of transporters is triggered by their ubiquitylation mediated by the Rsp5 ubiquitin-ligase, recruited by α-arrestin–family adaptors. We here report that transport-elicited ubiquitylation of the arginine transporter Can1 is promoted by transition to an inward-facing state. This conformational change unveils a region of the N-terminal cytosolic tail targeted by the Art1 α-arrestin, which is activated via the TORC1 kinase complex upon arginine uptake. Can1 mutants altered in the arginine-binding site or a cytosolic tripeptide sequence permanently expose the α-arrestin–targeted region so that Art1 activation via TORC1 is sufficient to trigger their endocytosis. We also provide evidence that substrate-transport elicited endocytosis of other amino acid permeases similarly involves unmasking of a cytosolic Art1-target region coupled to activation of Art1 via TORC1. Our results unravel a mechanism likely involved in regulation of many other transporters by their own substrates. They also support the emerging view that transporter ubiquitylation relies on combinatorial interaction rules such that α-arrestins, stimulated via signaling cascades or in their basal state, recognize transporter regions permanently facing the cytosol or unveiled during transport.

4-Acetyl-12,13-Epoxyl-9-Trichothecene-3,15-Diol from Isaria japonica Mediates Apoptosis of Rat Bladder Carcinoma NBT-II Cells by Decreasing Anti-apoptotic Bcl-2 Expression and Increasing Pro-apoptotic Bax Expression

2004 ◽  
Vol 32 (03) ◽  
pp. 377-387 ◽  
Author(s):  
Hyung-Jin Kim ◽  
Seon Il Jang ◽  
Young-Jun Kim ◽  
Hyun-Ock Pae ◽  
Hae-Young Won ◽  
...  
Keyword(s):  
Cell Death ◽  
Bladder Carcinoma ◽  
Cytotoxic Effect ◽  
Caspase 3 ◽  
Apoptotic Cell ◽  
Morphological Changes ◽  
Rat Bladder ◽  
Apoptotic Protein ◽  
Induction Of Apoptosis ◽  
Induced Apoptosis

We studied the effect of 4-acetyl-12,13-epoxyl-9-trichothecene-3,15-diol (AETD) isolated from Isaria japonica, one of the most popular Chinese fungal medicines, on the induction of apoptosis in rat bladder carcinoma NBT-II cells. AETD was cytotoxic to NBT-II cells, and this cytotoxic effect appears to be attributed to its induction of apoptotic cell death, as AETD induced nuclear morphological changes and internucleosomal DNA fragmentation, and increased the proportion of hypodiploid cells and activity of caspase-3. AETD treatment also decreased the expression of the anti-apoptotic protein Bcl-2 and increased the expression of the pro-apoptotic protein Bax. These results provide important information in understanding the mechanism(s) of AETD-induced apoptosis.

scholarly journals CSIG-18. NERVE/GLIAL ANTIGEN (NG)2 EXPRESSION IN GLIOBLASTOMA IS REGULATED BY miR-29b-3p

2019 ◽  
Vol 21 (Supplement_6) ◽  
pp. vi47-vi48
Author(s):  
Beate Schmitt ◽  
Anne Boewe ◽  
Yuan Gu ◽  
Christoph Sippl ◽  
Steffi Urbschat ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Cell Lines ◽  
Therapeutic Strategy ◽  
Mrna Levels ◽  
Glioblastoma Cell ◽  
Glioblastoma Cells ◽  
Qrt Pcr ◽  
Glioblastoma Patient ◽  
Low Levels ◽  
Glioblastoma Cell Lines

Abstract Overexpression of NG2 in human glioblastoma cells is associated with an elevated drug resistance and thereby worsens clinical outcome. However, the regulatory mechanisms of NG2 expression are largely unknown. In this study, we identified miR-29b-3p as a posttranscriptional factor of NG2 expression. The basal mRNA levels of miR-29b-3p and NG2 were detected in the NG2-positive glioblastoma cell lines A1207 and U87 by qRT-PCR. The cells were transfected with miR-29b-3p-mimic or scrambled-miR (control) and the expression of NG2 was analyzed by qRT-PCR, flow cytometry and Western blot. Reporter gene analyses of the NG2 promotor region and 3’UTR were performed to study the effect of miR-29b-3p on NG2 expression. Finally, we analyzed the mRNA levels of NG2 and miR-29b-3p in samples from glioblastoma patients. We found that the two NG2-positive glioblastoma cell lines A1207 and U87 are positive for miR-29b-3p. Transfection with miR-29b-3p-mimic reduced NG2 mRNA levels in A1207 (29%±9.9; Mean±SD) and U87 (6%±2.8), resulting in a significantly decreased NG2 protein expression in A1207 (67%±6.4) and U87 (75%±4) when compared to controls. The analysis of the 3’UTR revealed that miR-29b-3p is a posttranscriptional regulator of NG2 expression. Moreover, miR-29b-3p affects the pretranscriptional NG2 expression by diminishing SP-1-dependent NG2 promotor activity. These results were confirmed by the analysis of glioblastoma patient-derived samples, demonstrating that a high NG2 expression is associated with low levels of miR-29b-3p. In conclusion, we identified miR-29b-3p as a crucial regulator of NG2 expression in glioblastoma. Hence, targeting NG2 expression by miR-29b-3p may provide a novel therapeutic strategy to overcome drug resistance in NG2-positive glioblastoma cells.

scholarly journals Strategies for the identification of ubiquitin ligase inhibitors

2010 ◽  
Vol 38 (1) ◽  
pp. 132-136 ◽  
Author(s):  
Seth J. Goldenberg ◽  
Jeffrey G. Marblestone ◽  
Michael R. Mattern ◽  
Benjamin Nicholson
Keyword(s):  
Ubiquitin Ligase ◽  
Therapeutic Target ◽  
Therapeutic Strategy ◽  
Ubiquitin Proteasome System ◽  
Advantages And Disadvantages ◽  
Wide Range ◽  
Attractive Therapeutic Target ◽  
Ubiquitin Proteasome ◽  
Effective Therapeutic Strategy ◽  
Protein Ligases

Dysregulation of the UPS (ubiquitin–proteasome system) has been implicated in a wide range of pathologies including cancer, neurodegeneration and viral infection. Inhibiting the proteasome has been shown to be an effective therapeutic strategy in humans; however, toxicity with this target remains high. E3s (Ub–protein ligases) represent an alternative attractive therapeutic target in the UPS. In this paper, we will discuss current platforms that report on E3 ligase activity and can detect E3 inhibitors, and underline the advantages and disadvantages of each approach.

scholarly journals Synergism Through WEE1 and CHK1 Inhibition in Acute Lymphoblastic Leukemia

Cancers ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 1654 ◽  
Author(s):  
Ghelli Luserna Di Rorà ◽  
Bocconcelli ◽  
Ferrari ◽  
Terragna ◽  
Bruno ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Death ◽  
Acute Lymphoblastic Leukemia ◽  
Cell Lines ◽  
Therapeutic Strategy ◽  
Synthetic Lethality ◽  
Ex Vivo ◽  
Lymphoblastic Leukemia ◽  
Cell Cycle Checkpoint ◽  
Induction Of Apoptosis

Introduction: Screening for synthetic lethality markers has demonstrated that the inhibition of the cell cycle checkpoint kinases WEE1 together with CHK1 drastically affects stability of the cell cycle and induces cell death in rapidly proliferating cells. Exploiting this finding for a possible therapeutic approach has showed efficacy in various solid and hematologic tumors, though not specifically tested in acute lymphoblastic leukemia. Methods: The efficacy of the combination between WEE1 and CHK1 inhibitors in B and T cell precursor acute lymphoblastic leukemia (B/T-ALL) was evaluated in vitro and ex vivo studies. The efficacy of the therapeutic strategy was tested in terms of cytotoxicity, induction of apoptosis, and changes in cell cycle profile and protein expression using B/T-ALL cell lines. In addition, the efficacy of the drug combination was studied in primary B-ALL blasts using clonogenic assays. Results: This study reports, for the first time, the efficacy of the concomitant inhibition of CHK1/CHK2 and WEE1 in ALL cell lines and primary leukemic B-ALL cells using two selective inhibitors: PF-0047736 (CHK1/CHK2 inhibitor) and AZD-1775 (WEE1 inhibitor). We showed strong synergism in the reduction of cell viability, proliferation and induction of apoptosis. The efficacy of the combination was related to the induction of early S-phase arrest and to the induction of DNA damage, ultimately triggering cell death. We reported evidence that the efficacy of the combination treatment is independent from the activation of the p53-p21 pathway. Moreover, gene expression analysis on B-ALL primary samples showed that Chek1 and Wee1 are significantly co-expressed in samples at diagnosis (Pearson r = 0.5770, p = 0.0001) and relapse (Pearson r= 0.8919; p = 0.0001). Finally, the efficacy of the combination was confirmed by the reduction in clonogenic survival of primary leukemic B-ALL cells. Conclusion: Our findings suggest that the combination of CHK1 and WEE1 inhibitors may be a promising therapeutic strategy to be tested in clinical trials for adult ALL.

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