CBL mutations drive PI3K/AKT signaling via increased interaction with LYN and PIK3R1

Blood ◽  
2021 ◽  
Author(s):  
Roger Belizaire ◽  
Sebastian Hassan John Koochaki ◽  
Namrata D. Udeshi ◽  
Alexis Vedder ◽  
Lei Sun ◽  
...  
Keyword(s):  
Cell Lines ◽  
Ubiquitin Ligase ◽  
Therapeutic Potential ◽  
Mutant Cell ◽  
E3 Ubiquitin Ligase ◽  
Akt Signaling ◽  
Allelic Series ◽  
Genetic Ablation

CBL encodes an E3 ubiquitin ligase and signaling adaptor that regulates receptor and non-receptor tyrosine kinases. Recurrent CBL mutations occur in myeloid neoplasms, including 10-20% of chronic myelomonocytic leukemia (CMML) cases, and selectively disrupt the protein's E3 ubiquitin ligase activity. CBL mutations have been associated with poor prognosis, but the oncogenic mechanisms and therapeutic implications of CBL mutations remain incompletely understood. We combined functional assays and global mass spectrometry to define the phosphoproteome, CBL interactome, and mechanism of signaling activation in a panel of cell lines expressing an allelic series of CBL mutations. Our analyses revealed that increased LYN activation and interaction with mutant CBL are key drivers of enhanced CBL phosphorylation, PIK3R1 recruitment, and downstream PI3K/AKT signaling in CBL-mutant cells. Signaling adaptor domains of CBL, including the tyrosine-kinase binding domain, proline-rich region, and C-terminal phosphotyrosine sites, were all required for the oncogenic function of CBL mutants. Genetic ablation or dasatinib-mediated inhibition of LYN reduced CBL phosphorylation, CBL-PIK3R1 interaction, and PI3K/AKT signaling. Furthermore, we demonstrated in vitro and in vivo antiproliferative efficacy of dasatinib in CBL-mutant cell lines and primary CMML. Overall, these mechanistic insights into the molecular function of CBL mutations provide rationale to explore the therapeutic potential of LYN inhibition in CBL-mutant myeloid malignancies.

CBL mutations promote activation of PI3K/AKT signaling via LYN kinase

2020 ◽  
Author(s):  
Roger Belizaire ◽  
Sebastian H.J. Koochaki ◽  
Namrata D. Udeshi ◽  
Alexis Vedder ◽  
Lei Sun ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Therapeutic Potential ◽  
Mutant Cell ◽  
Akt Signaling ◽  
Allelic Series ◽  
Myeloid Malignancies ◽  
Lyn Kinase ◽  
Mutant Cells

AbstractCBL encodes an E3 ubiquitin ligase and signaling adaptor that acts downstream of cytokine receptors. Recurrent CBL mutations occur in myeloid malignancies, but the mechanism by which these mutations drive oncogenesis remains incompletely understood. Here we performed a series of studies to define the phosphoproteome, CBL interactome and molecular mechanisms of signaling activation in cells expressing an allelic series of CBL mutants. Our analyses revealed that increased LYN activation and interaction with mutant CBL are key drivers of enhanced PIK3R1 recruitment and downstream PI3K/AKT signaling in CBL-mutant cells. Furthermore, we demonstrated in vitro and in vivo efficacy of LYN inhibition by dasatinib in CBL-mutant cell lines and primary chronic myelomonocytic leukemia cells. Overall, our data provide rationale for exploring the therapeutic potential of LYN inhibition in patients with CBL-mutated myeloid malignancies.Statement of SignificanceWe investigated the oncogenic mechanisms of myeloid malignancy-associated CBL mutations by mass spectrometry-based proteomics and interactomics. Our findings indicate that increased LYN kinase activity in CBL-mutant cells stimulates PI3K/AKT signaling, revealing opportunities for the use of targeted inhibitors in CBL-mutated myeloid malignancies.

scholarly journals E3 Ubiquitin Ligase SPL2 Is a Lanthanide-Binding Protein

2021 ◽  
Vol 22 (11) ◽  
pp. 5712
Author(s):  
Michał Tracz ◽  
Ireneusz Górniak ◽  
Andrzej Szczepaniak ◽  
Wojciech Białek
Keyword(s):  
Ubiquitin Ligase ◽  
Conformational Changes ◽  
Protein Interactions ◽  
E3 Ubiquitin Ligase ◽  
Lanthanide Ions ◽  
E3 Ligases ◽  
Fluorescence Measurements ◽  
Partial Unfolding

The SPL2 protein is an E3 ubiquitin ligase of unknown function. It is one of only three types of E3 ligases found in the outer membrane of plant chloroplasts. In this study, we show that the cytosolic fragment of SPL2 binds lanthanide ions, as evidenced by fluorescence measurements and circular dichroism spectroscopy. We also report that SPL2 undergoes conformational changes upon binding of both Ca2+ and La3+, as evidenced by its partial unfolding. However, these structural rearrangements do not interfere with SPL2 enzymatic activity, as the protein retains its ability to auto-ubiquitinate in vitro. The possible applications of lanthanide-based probes to identify protein interactions in vivo are also discussed. Taken together, the results of this study reveal that the SPL2 protein contains a lanthanide-binding site, showing for the first time that at least some E3 ubiquitin ligases are also capable of binding lanthanide ions.

scholarly journals Tanshinone IIA Inhibits Osteosarcoma Growth through a Src Kinase-Dependent Mechanism

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Chao Hu ◽  
Xiaobin Zhu ◽  
Taogen Zhang ◽  
Zhouming Deng ◽  
Yuanlong Xie ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Signaling Pathways ◽  
Cell Lines ◽  
Src Kinase ◽  
Akt Signaling ◽  
Cellular Level ◽  
Tanshinone Iia

Introduction. Osteosarcoma is a malignant tumor associated with high mortality rates due to the toxic side effects of current therapeutic methods. Tanshinone IIA can inhibit cell proliferation and promote apoptosis in vitro, but the exact mechanism is still unknown. The aims of this study are to explore the antiosteosarcoma effect of tanshinone IIA via Src kinase and demonstrate the mechanism of this effect. Materials and Methods. Osteosarcoma MG-63 and U2-OS cell lines were stable transfections with Src-shRNA. Then, the antiosteosarcoma effect of tanshinone IIA was tested in vitro. The protein expression levels of Src, p-Src, p-ERK1/2, and p-AKt were detected by Western blot and RT-PCR. CCK-8 assay and BrdU immunofluorescence assay were used to detect cell proliferation. Transwell assay, cell scratch assay, and flow cytometry were used to detect cell invasion, migration, and cell cycle. Tumor-bearing nude mice with osteosarcoma were constructed. The effect of tanshinone IIA was detected by tumor HE staining, tumor inhibition rate, incidence of lung metastasis, and X-ray. Results. The oncogene role of Src kinase in osteosarcoma is reflected in promoting cell proliferation, invasion, and migration and in inhibiting apoptosis. However, Src has different effects on cell proliferation, apoptosis, and cell cycle regulation among cell lines. At a cellular level, the antiosteosarcoma effect of tanshinone IIA is mediated by Src downstream of the MAPK/ERK and PI3K/AKt signaling pathways. At the animal level, tanshinone IIA played a role in resisting osteosarcoma formation by Src downstream of the MAPK/ERK and PI3K/AKt signaling pathways. Conclusion. Tanshinone IIA plays an antiosteosarcoma role in vitro and in vivo and inhibits the progression of osteosarcoma mediated by Src downstream of the MAPK/ERK and PI3K/AKt signaling pathways.

scholarly journals Hakin-1, a New Specific Small-Molecule Inhibitor for the E3 Ubiquitin-Ligase Hakai, Inhibits Carcinoma Growth and Progression

Cancers ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1340 ◽  
Author(s):  
Olaia Martinez-Iglesias ◽  
Alba Casas-Pais ◽  
Raquel Castosa ◽  
Andrea Díaz-Díaz ◽  
Daniel Roca-Lema ◽  
...  
Keyword(s):  
Small Molecule ◽  
Ubiquitin Ligase ◽  
Epithelial To Mesenchymal Transition ◽  
Tumour Progression ◽  
E3 Ubiquitin Ligase ◽  
Therapeutic Drug ◽  
Mesenchymal Transition ◽  
E Cadherin

The requirement of the E3 ubiquitin-ligase Hakai for the ubiquitination and subsequent degradation of E-cadherin has been associated with enhanced epithelial-to-mesenchymal transition (EMT), tumour progression and carcinoma metastasis. To date, most of the reported EMT-related inhibitors were not developed for anti-EMT purposes, but indirectly affect EMT. On the other hand, E3 ubiquitin-ligase enzymes have recently emerged as promising therapeutic targets, as their specific inhibition would prevent wider side effects. Given this background, a virtual screening was performed to identify novel specific inhibitors of Hakai, targeted against its phosphotyrosine-binding pocket, where phosphorylated-E-cadherin specifically binds. We selected a candidate inhibitor, Hakin-1, which showed an important effect on Hakai-induced ubiquitination. Hakin-1 also inhibited carcinoma growth and tumour progression both in vitro, in colorectal cancer cell lines, and in vivo, in a tumour xenograft mouse model, without apparent systemic toxicity in mice. Our results show for the first time that a small molecule putatively targeting the E3 ubiquitin-ligase Hakai inhibits Hakai-dependent ubiquitination of E-cadherin, having an impact on the EMT process. This represents an important step forward in a future development of an effective therapeutic drug to prevent or inhibit carcinoma tumour progression.

In vitro and in vivo activity of ATP-based kinase inhibitors AP23464 and AP23848 against activation-loop mutants of Kit

Blood ◽  
2005 ◽  
Vol 106 (1) ◽  
pp. 227-234 ◽  
Author(s):  
Amie S. Corbin ◽  
Shadmehr Demehri ◽  
Ian J. Griswold ◽  
Yihan Wang ◽  
Chester A. Metcalf ◽  
...  
Keyword(s):  
Cell Lines ◽  
Kinase Inhibitors ◽  
Therapeutic Potential ◽  
Systemic Mastocytosis ◽  
Myelogenous Leukemia ◽  
Therapeutic Window ◽  
Hematopoietic Progenitor Cell ◽  
Activation Loop

Oncogenic mutations of the Kit receptor tyrosine kinase occur in several types of malignancy. Juxtamembrane domain mutations are common in gastrointestinal stromal tumors, whereas mutations in the kinase activation loop, most commonly D816V, are seen in systemic mastocytosis and acute myelogenous leukemia. Kit activation-loop mutants are insensitive to imatinib mesylate and have been largely resistant to targeted inhibition. We determined the sensitivities of both Kit mutant classes to the adenosine triphosphate (ATP)–based inhibitors AP23464 and AP23848. In cell lines expressing activation-loop mutants, low-nM concentrations of AP23464 inhibited phosphorylation of Kit and its downstream targets Akt and signal transducer and activator of transcription 3 (STAT3). This was associated with cell-cycle arrest and apoptosis. Wild-type Kit–and juxtamembrane-mutant–expressing cell lines required considerably higher concentrations for equivalent inhibition, suggesting a therapeutic window in which cells harboring D816V Kit could be eliminated without interfering with normal cellular function. Additionally, AP23464 did not disrupt normal hematopoietic progenitor-cell growth at concentrations that inhibited activation-loop mutants of Kit. In a murine model, AP23848 inhibited activation-loop mutant Kit phosphorylation and tumor growth. Thus, AP23464 and AP23848 potently and selectively target activation-loop mutants of Kit in vitro and in vivo and could have therapeutic potential against D816V-expressing malignancies.

scholarly journals TSPAN7 Exerts Anti-Tumor Effects in Bladder Cancer Through the PTEN/PI3K/AKT Pathway

2021 ◽  
Vol 10 ◽  
Author(s):  
Xi Yu ◽  
Shenglan Li ◽  
Mingrui Pang ◽  
Yang Du ◽  
Tao Xu ◽  
...  
Keyword(s):  
Bladder Cancer ◽  
Cell Lines ◽  
Therapeutic Potential ◽  
Tumor Grade ◽  
Biological Properties ◽  
Akt Pathway ◽  
Dynamic Regulation ◽  
Potential Marker

The tetraspanin protein superfamily participate in the dynamic regulation of cellular membrane compartments expressed in a variety of tumor types, which may alter the biological properties of cancer cells such as cell development, activation, growth and motility. The role of tetraspanin 7 (TSPAN7) has never been investigated in bladder cancer (BCa). In this study, we aimed to investigate the biological function of TSPAN7 and its therapeutic potential in human BCa. First, via reverse transcription and quantitative real-time PCR (qRT-PCR), we observed downregulation of TSPAN7 in BCa tissues samples and cell lines and found that this downregulation was associated with a relatively high tumor stage and tumor grade. Low expression of TSPAN7 was significantly correlated with a much poorer prognosis for BCa patients than was high expression. Immunohistochemistry (IHC) showed that low TSPAN7 expression was a high-risk predictor of BCa patient overall survival. Furthermore, the inhibitory effects of TSPAN7 on the proliferation and migration of BCa cell lines were detected by CCK-8, wound-healing, colony formation and transwell assays in vitro. Flow cytometry analysis revealed that TSPAN7 induced BCa cell lines apoptosis and cell cycle arrest. In vivo, tumor growth in nude mice bearing tumor xenografts could be obviously affected by overexpression of TSPAN7. Western blotting showed that overexpression of TSPAN7 activated Bax, cleaved caspase-3 and PTEN but inactivated Bcl-2, p-PI3K, and p-AKT to inhibit BCa cell growth via the PTEN/PI3K/AKT pathway. Taken together, our study will help identify a potential marker for BCa diagnosis and supply a target molecule for BCa treatment.

Regulation of HDM2 E3-ubiquitin ligase in esophageal adenocarcinoma cells by AURKA.

2013 ◽  
Vol 31 (4_suppl) ◽  
pp. 35-35
Author(s):  
Vikas Sehdev ◽  
Abbes Belkhiri ◽  
Mohammed Soutto ◽  
Ahmed M. Katsha ◽  
Wael El-Rifai
Keyword(s):  
Cell Lines ◽  
Ubiquitin Ligase ◽  
E3 Ubiquitin Ligase ◽  
Direct Interaction ◽  
Kinase Assay ◽  
Intrinsic Resistance ◽  
Tissue Samples ◽  
Protein Levels ◽  
Eac Cells

35 Background: Esophageal adenocarcinomas (EAC) exhibit intrinsic resistance against chemotherapy. AURKA regulates cell cycle progression and its overexpression is associated with oncogenic transformation. We have recently reported that AURKA is significantly overexpressed in about 70% of human EAC tissue samples and EAC cell lines. We have previously shown that AURKA inhibits p53- and p73-mediated apoptotic pathways in GI adenocarcinomas. HDM2 is an E3-ubiquitin ligase which is closely involved in regulating p53 and p73 protein stability and activity. In this study we demonstrate that AURKA directly interacts with HDM2 and regulates HDM2 protein expression and phosphorylation in both FLO-1 and OE33 EAC cells. Methods and Results: Western blot analyses were done following AURKA overexpression with adenovirus, knockdown with si-RNA or inhibition with MLN 8237 (0.5µM) in FLO-1 and OE33 EAC cell lines. The data indicated that overexpression of AURKA induced both total and phospho-HDM2-(Ser166) protein levels. Knockdown or inhibition of AURKA significantly decreased expression of both total and phospho-HDM2-(Ser166) protein levels in FLO-1 and OE33 EAC cells. Additionally, following adenovirus mediated overexpression of AURKA, co-immunoprecipitaion (Co-IP) was done for AURKA and HDM2 in FLO-1 and OE33 EAC cells. The two-way Co-IP data indicated the presence of HDM2 in a complex associated with AURKA and vice-versa. The data from in vitro protein kinase assay indicated that recombinant AURKA directly phosphorylates recombinant HDM2 at Ser166 site. To confirm direct interaction between recombinant AURKA and HDM2 proteins we performed IP following the in vitro kinase assay. The in vitro kinase IP data indicates that kinase intact recombinant AURKA directly interacts and phosphorylates recombinant HDM2 protein. Conclusions: Our data indicate that AURKA regulates HDM2 expression and phosphorylation in both FLO-1 and OE33 EAC cells. Additionally, we also report for the first time that AURKA directly interacts with HDM2 and phosphorylates it at Ser166 site. Therefore, our study suggests that AURKA-mediated regulation of HDM2 could be the major underlying mechanism for induction of apoptosis in p53-negative EAC.

Effect of MM-141 on gemcitabine and nab-paclitaxel potentiation in preclinical models of pancreatic cancer through induction of IGF-1R and ErbB3 degradation.

2015 ◽  
Vol 33 (3_suppl) ◽  
pp. 289-289 ◽  
Author(s):  
Emily Pace ◽  
Sharlene Adams ◽  
Adam Camblin ◽  
Michael Curley ◽  
Victoria Rimkunas ◽  
...  
Keyword(s):  
Pancreatic Cancer ◽  
Pancreatic Adenocarcinoma ◽  
Cell Lines ◽  
Stage Iv ◽  
Akt Signaling ◽  
Preclinical Models ◽  
Patient Response ◽  
Receptor Complexes

289 Background: Gemcitabine, the first-line treatment for pancreatic cancer, has been improved by addition of nab-paclitaxel. However, patient response to this regimen is limited. Oncogenic insulin-like growth factor 1 (IGF-1) and heregulin (HRG) signaling are associated with increased cancer risk and decreased response to anti-metabolites and taxanes. Therefore, we explored MM-141, a novel bispecific antibody that blocks ErbB3 and IGF-1 receptor (IGF-1R) signaling, in combination with nab-paclitaxel and gemcitabine in preclinical models of pancreatic cancer. Methods: Combinations with MM-141, gemcitabine, and nab-paclitaxel were investigated in pancreatic cancer cell lines, in vitro and in vivo. The effects of MM-141, gemcitabine, and nab-paclitaxel on tumor growth and signaling were measured by 3D spheroid growth, ELISA, Western, and mouse xenograft experiments. Results: In vitro studies show that IGF-1 and HRG are potent activators of AKT signaling, leading to increased pancreatic tumor cell proliferation and decreased sensitivity to gemcitabine and nab-paclitaxel. MM-141 inhibits ligand-induced AKT activation, induces IGF-1R and ErbB3 degradation better than a mixture of IGF-1R and ErbB3 antibodies, and sensitizes cells to gemcitabine and nab-paclitaxel, in vitro. In vivo, MM-141 combines favorably with a nab-paclitaxel/gemcitabine regimen, leading to curative outcomes in a subset of treated mice. Conclusions: ErbB3 and IGF-1R co-inhibition is required to inhibit AKT signaling in pancreatic adenocarcinoma cell lines. These receptors are associated with chemoresistance to gemcitabine and nab-paclitaxel, which is abrogated by co-administration with MM-141. MM-141-induced degradation of oncogenic receptor complexes is likely essential to reverse chemoresistance and enhance effects of the nab-paclitaxel/gemcitabine regimen. These data, taken together with wide-spread expression of IGF-1R and ErbB3 in Stage IV pancreatic adenocarcinoma tissue, support clinical exploration of a MM-141/nab-paclitaxel/gemcitabine regimen in frontline metastatic pancreatic cancer. Preparations for a randomized Phase 2 study are underway.

Abstract 241: MDM2 E3 Ligase-mediated Ubiquitination and Degradation of HDAC1 in Vascular Calcification

2016 ◽  
Vol 119 (suppl_1) ◽  
Author(s):  
Hyun Kook ◽  
Duk-Hwa Kwon ◽  
Gwang Hyeon Eom ◽  
Hyun-Ki Min ◽  
Somy Yoon ◽  
...  
Keyword(s):  
Vascular Calcification ◽  
Ubiquitin Ligase ◽  
Molecular Mechanisms ◽  
Metabolic Diseases ◽  
Genetic Ablation ◽  
Histone Deacetylase 1 ◽  
Ubiquitination Pathway ◽  
Mdm2 Inhibitor

Vascular calcification (VC) is often associated with cardiovascular and metabolic diseases. However, the molecular mechanisms linking VC to these diseases have yet to be elucidated. Here we report that MDM2-induced ubiquitination of histone deacetylase 1 (HDAC1) mediates VC. Loss of HDAC1 activity via either chemical inhibitor or genetic ablation enhances VC. HDAC1 protein, but not mRNA, is reduced in cell and animal calcification models and in human calcified coronary artery. Under calcification-inducing conditions, proteasomal degradation of HDAC1 precedes VC and it is mediated by MDM2 E3 ubiquitin ligase that initiates HDAC1 K74 ubiquitination. Overexpression of MDM2 enhances VC, whereas loss of MDM2 blunts it. Decoy peptide spanning HDAC1 K74 and RG 7112, an MDM2 inhibitor, prevent VC in vivo and in vitro. These results uncover a previously unappreciated ubiquitination pathway and suggest MDM2-mediated HDAC1 ubiquitination as a new therapeutic target in VC.

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