scholarly journals MBRS-65. FBXW7 ACTS A TUMOR SUPPRESSOR IN MYC-DRIVEN MEDULLOBLASTOMA BY CONTROLLING A FEED-FORWARD REGULATORY LOOP OF PLK1 AND MYC

2020 ◽  
Vol 22 (Supplement_3) ◽  
pp. iii409-iii409
Author(s):  
Dong Wang ◽  
Angela Pierce ◽  
Bethany Veo ◽  
Susan Fosmire ◽  
Krishna Madhavan ◽  
...  
Keyword(s):  
Tumor Suppressor ◽  
Kinase Inhibitors ◽  
Proteasomal Degradation ◽  
Tumor Suppressor Function ◽  
Group 3 ◽  
Regulatory Loop ◽  
Proliferation In Vitro ◽  
Lower Expression

Abstract Group 3 medulloblastoma (MB) is often accompanied by MYC amplification and has a higher rate of metastatic disease. So, it is critical to have more effective therapies for high MYC expressing sub-groups. Here we report that FBXW7, a substrate recognition component of the SKP1-CUL1-Fbox (SCF) E3 ligase, interacts with and targets c-MYC for polyubiquitination and proteasomal degradation. FBXW7 shows lower expression level in MYC-driven MB compared with other MB subgroups suggesting activity as a tumor suppressor. Genomic deletion or mutation of Fbxw7 has frequently been identified in many human cancers but not in MB. We demonstrate that overexpression of Fbxw7 in MB cells induces apoptosis and suppresses proliferation in vitro and in vivo. Both phospho-deficient (T205A) and phosphomimetic aspartic acid (T205D) mutants deactivate its tumor suppressor function suggesting a conformational change of its protein structure. Mechanistically, PLK1 kinase specifically phosphorylates FBXW7 and promotes its auto-polyubiquitination and proteasomal degradation, counteracting FBXW7-mediated degradation of oncogene substrates, including c-MYC and PLK1. Chip-Seq results show stabilized c-MYC in turn directly activates PLK1 and FBXW7 transcription, constituting a feedforward regulatory loop. Co-immunoprecipitation demonstrates that FBXW7 directly binds to PLK1 and c-MYC, facilitating their protein degradation by promoting the ubiquitination of both proteins. Furthermore, we show that FBXW7 protein can be stabilized by various kinase inhibitors, proposing a mechanism of kinase-targeted agents to treat MYC-driven MB. These results collectively demonstrate how kinase inhibition stabilizes the tumor suppressor FBXW7 in MYC-driven MB, thus revealing an important function of FBXW7 in suppressing MB progression.

scholarly journals A Regulatory Loop of FBXW7-MYC-PLK1 Controls Tumorigenesis of MYC-Driven Medulloblastoma

Cancers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 387
Author(s):  
Dong Wang ◽  
Angela Pierce ◽  
Bethany Veo ◽  
Susan Fosmire ◽  
Etienne Danis ◽  
...  
Keyword(s):  
Tumor Development ◽  
Tumor Suppressor Function ◽  
Protein Levels ◽  
Group 3 ◽  
Induced Apoptosis ◽  
Regulatory Loop ◽  
Proliferation In Vitro ◽  
Constitutive Phosphorylation

Polo-like kinase 1 (PLK1) is highly expressed in group 3 medulloblastoma (MB), and it has been preclinically validated as a cancer therapeutic target in medulloblastoma. Here, we demonstrate that PLK1 inhibition with PCM-075 or BI6727 significantly reduces the growth of MB cells and causes a decrease of c-MYC mRNA and protein levels. We show that MYC activates PLK1 transcription, while the inhibition of PLK1 suppresses MB tumor development and causes a decrease in c-MYC protein level by suppressing FBXW7 auto poly-ubiquitination. FBXW7 physically interacts with PLK1 and c-MYC, facilitating their protein degradation by promoting ubiquitination. These results demonstrate a PLK1-FBXW7-MYC regulatory loop in MYC-driven medulloblastoma. Moreover, FBXW7 is significantly downregulated in group 3 patient samples. The overexpression of FBXW7 induced apoptosis and suppressed proliferation in vitro and in vivo, while constitutive phosphorylation mutation attenuated its tumor suppressor function. Altogether, these findings demonstrated that PLK1 inhibition stabilizes FBXW7 in MYC-driven MB, thus revealing an important function of FBXW7 in suppressing medulloblastoma progression.

scholarly journals Tumor Suppressor Function of miR-127-3p and miR-376a-3p in Osteosarcoma Cells

Cancers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2019 ◽  
Author(s):  
Joerg Fellenberg ◽  
Burkhard Lehner ◽  
Heiner Saehr ◽  
Astrid Schenker ◽  
Pierre Kunz
Keyword(s):  
Tumor Suppressor ◽  
Therapeutic Strategies ◽  
High Dose ◽  
Osteosarcoma Cell ◽  
Tumor Suppressor Function ◽  
Osteosarcoma Cells ◽  
Aberrant Expression ◽  
Suppressor Function

Since the introduction of high-dose chemotherapy about 35 years ago, survival rates of osteosarcoma patients have not been significantly improved. New therapeutic strategies replacing or complementing conventional chemotherapy are therefore urgently required. MicroRNAs represent promising targets for such new therapies, as they are involved in the pathology of multiple types of cancer, and aberrant expression of several miRNAs has already been shown in osteosarcoma. In this study, we identified silencing of miR-127-3p and miR-376a-3p in osteosarcoma cell lines and tissues and investigated their role as potential tumor suppressors in vitro and in vivo. Transfection of osteosarcoma cells (n = 6) with miR-127-3p and miR-376a-3p mimics significantly inhibited proliferation and reduced the colony formation capacity of these cells. In contrast, we could not detect any influence of miRNA restoration on cell cycle and apoptosis induction. The effects of candidate miRNA restoration on tumor engraftment and growth in vivo were analyzed using a chicken chorioallantoic membrane (CAM) assay. Cells transfected with mir-127-3p and miR-376a-3p showed reduced tumor take rates and tumor volumes and a significant decrease of the cumulative tumor volumes to 41% and 54% compared to wildtype cells. The observed tumor suppressor function of both analyzed miRNAs indicates these miRNAs as potentially valuable targets for the development of new therapeutic strategies for the treatment of osteosarcoma.

scholarly journals MiR-212-3p functions as a tumor suppressor gene in group 3 medulloblastoma via targeting nuclear factor I/B (NFIB)

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Naveenkumar Perumal ◽  
Ranjana K. Kanchan ◽  
David Doss ◽  
Noah Bastola ◽  
Pranita Atri ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Tumor Suppressor ◽  
Cancer Cell ◽  
Migration And Invasion ◽  
Stem Cell Markers ◽  
Cancer Cell Proliferation ◽  
Group 3

AbstractHaploinsufficiency of chromosome 17p and c-Myc amplification distinguish group 3 medulloblastomas which are associated with early metastasis, rapid recurrence, and swift mortality. Tumor suppressor genes on this locus have not been adequately characterized. We elucidated the role of miR-212-3p in the pathophysiology of group 3 tumors. First, we learned that miR-212-3p undergoes epigenetic silencing by histone modifications in group 3 tumors. Restoring its expression reduced cancer cell proliferation, migration, colony formation, and wound healing in vitro and attenuated tumor burden and improved survival in vivo. MiR-212-3p also triggered c-Myc destabilization and degradation, leading to elevated apoptosis. We then isolated an oncogenic target of miR-212-3p, i.e. NFIB, a nuclear transcription factor implicated in metastasis and recurrence in various cancers. Increased expression of NFIB was confirmed in group 3 tumors and associated with poor survival. NFIB silencing reduced cancer cell proliferation, migration, and invasion. Concurrently, reduced medullosphere formation and stem cell markers (Nanog, Oct4, Sox2, CD133) were noted. These results substantiate the tumor-suppressive role of miR-212-3p in group 3 MB and identify a novel oncogenic target implicated in metastasis and tumor recurrence.

scholarly journals Distinct Gene Expression Patterns Drive Proliferation of Dominant-Negative RUNX1 Immortalized HSPCs

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 1795-1795
Author(s):  
Samantha K Langer ◽  
Alyssa Cull ◽  
Natalie Wossidlo ◽  
Hannes Klump ◽  
Peter A. Horn ◽  
...  
Keyword(s):  
Gene Expression ◽  
Stem Cells ◽  
Bone Marrow ◽  
Tumor Suppressor ◽  
Dominant Negative ◽  
Tumor Suppressor Function ◽  
Self Renewal ◽  
Hematopoietic Stem

Abstract The transcription factor RUNX1 is a master regulator of normal hematopoiesis and is involved in cell fate decisions. RUNX1 mutations have been shown to contribute to the development of myeloid neoplasms, and in myelodysplastic syndromes (MDS) it is one of the most frequently mutated genes. Such mutations lead to RUNX1 proteins that lack transactivation activity or DNA-binding ability resulting in a loss of its tumor suppressor function. The dominant-negative short isoform RUNX1a resembles truncated RUNX1 mutants and inhibits the function of the full-length RUNX1 proteins. Additionally, a recently published study identified overexpression of RUNX1a but not full-length RUNX1 in CD34+-cells from patients with myelodysplastic/myeloproliferative disease, which increased with disease progression. This strongly suggests that truncated RUNX1 plays a pivotal role in myelodysplastic disease. However, the precise molecular functions of mutating RUNX1, particularly with respect to the identity of RUNX1 target genes conferring its tumor suppressor function, remain unclear. Previously, our group reported that overexpression of RUNX1a immortalized murine hematopoietic stem and progenitor cells (HSPCs) in vitro. Immunophenotyping of these cells confirmed the expansion of an immature subpopulation defined as Lin- Sca1+ Kit+ (LSK). This phenotype was reversed upon turning RUNX1a-expression off and led to a loss of Sca1 expression (Lin- Kit+, LK). To further understand the molecular consequences of RUNX1a overexpression we sorted the LK cells and LSK cells before and 36h after RUNX1a-expression was turned off. Next, we performed microarray analysis to assess differential gene expression in these different subpopulations. Gene set enrichment analysis (GSEA) identified upregulation of genes highly expressed in hematopoietic stem cells (HSC) and leukemic stem cells (LSCs) in RUNX1a-expressing LSK cells compared to those LSK cells in which RUNX1a expression was turned off. Conversely, a gene signature associated with stemness and self-renewal was lost in LK-cells when RUNX1a expression was turned off. Among the eleven leading edge genes, we found genes implicated in leukemogenesis, stem cell regulation, or both such as Erg, Meis1 and Bcl11a. To further understand the role of RUNX1a in vivo we transplanted C57Bl6 mice (n=29) with HSPCs expressing RUNX1a in a competitive reconstitution setting. Consistent with the immortalization of HSPCs in vitro, RUNX1a-overexpressing HSPCs expanded in the bone marrow of transplanted mice. We observed significantly higher frequencies of LK (2.9-fold) and LSK cells (5-fold) in the RUNX1a-expressing bone marrow cells compared to transplanted control mice. High frequencies of RUNX1a-expressing cells in the bone marrow were associated with lower frequencies of RUNX1a-expressing cells in the peripheral blood indicating a differentiation block. In addition, we found that 85% of the RUNX1a-expressing cells were committed to the myeloid lineage (CD11b+/Ly6G+) at the expense of the lymphoid lineage (B220 and CD3e). Moreover, RUNX1a expression led to an increased percentage (65%) of immature erythroblasts (Ter119-) in the bone marrow compared to control cells (55%). In summary, we have demonstrated that RUNX1a overexpression immortalized HSPCs by upregulation of genes involved in leukemogenesis, stemness and self-renewal. In vivo such HSPCs showed a competitive advantage that was associated with a block of differentiation. Our study, particularly the gene expression analysis, provides novel insights into genetic drivers contributing to the development of myeloid malignancies in patients with RUNX1 mutations. Disclosures No relevant conflicts of interest to declare.

scholarly journals Tumor Suppressor Function of Syk in Human MCF10A In Vitro and Normal Mouse Mammary Epithelium In Vivo

PLoS ONE ◽  
2009 ◽  
Vol 4 (10) ◽  
pp. e7445 ◽  
Author(s):  
You Me Sung ◽  
Xuehua Xu ◽  
Junfeng Sun ◽  
Duane Mueller ◽  
Kinza Sentissi ◽  
...  
Keyword(s):  
Tumor Suppressor ◽  
Normal Mouse ◽  
Mammary Epithelium ◽  
Tumor Suppressor Function ◽  
Suppressor Function ◽  
Mouse Mammary Epithelium

scholarly journals An Acetylation/Deacetylation-SUMOylation Switch through a Phylogenetically Conserved ψKXEP Motif in the Tumor Suppressor HIC1 Regulates Transcriptional Repression Activity

2007 ◽  
Vol 27 (7) ◽  
pp. 2661-2675 ◽  
Author(s):  
Nicolas Stankovic-Valentin ◽  
Sophie Deltour ◽  
Jacob Seeler ◽  
Sébastien Pinte ◽  
Gérard Vergoten ◽  
...  
Keyword(s):  
Tumor Suppressor ◽  
Transcriptional Repression ◽  
Significant Loss ◽  
Class Iii ◽  
Mammalian Development ◽  
Subnuclear Localization ◽  
Regulatory Loop ◽  
Repression Domain

ABSTRACT Tumor suppressor HIC1 (hypermethylated in cancer 1) is a gene that is essential for mammalian development, epigenetically silenced in many human tumors, and involved in a complex pathway regulating P53 tumor suppression activity. HIC1 encodes a sequence-specific transcriptional repressor containing five Krüppel-like C2H2 zinc fingers and an N-terminal BTB/POZ repression domain. Here, we show that endogenous HIC1 is SUMOylated in vivo on a phylogenetically conserved lysine, K314, located in the central region which is a second repression domain. K314R mutation does not influence HIC1 subnuclear localization but significantly reduces its transcriptional repression potential, as does the mutation of the other conserved residue in the ψKXE consensus, E316A, or the overexpression of the deSUMOylase SSP3/SENP2. Furthermore, HIC1 is acetylated in vitro by P300/CBP. Strikingly, the K314R mutant is less acetylated than wild-type HIC1, suggesting that this lysine is a target for both SUMOylation and acetylation. We further show that HIC1 transcriptional repression activity is positively controlled by two types of deacetylases, SIRT1 and HDAC4, which increase the deacetylation and SUMOylation, respectively, of K314. Knockdown of endogenous SIRT1 by the transfection of short interfering RNA causes a significant loss of HIC1 SUMOylation. Thus, this dual-deacetylase complex induces either a phosphorylation-dependent acetylation-SUMOylation switch through a ψKXEXXSP motif, as previously shown for MEF2, or a phosphorylation-independent switch through a ψKXEP motif, as shown here for HIC1, since P317A mutation severely impairs HIC1 acetylation. Finally, our results demonstrate that HIC1 is a target of the class III deacetylase SIRT1 and identify a new posttranslational modification step in the P53-HIC1-SIRT1 regulatory loop.

Approach in improving potency and selectivity of kinase inhibitors: Allosteric kinase inhibitors

2020 ◽  
Vol 21 ◽  
Author(s):  
Shangfei Wei ◽  
Tianming Zhao ◽  
Jie Wang ◽  
Xin Zhai
Keyword(s):  
Protein Interactions ◽  
Kinase Inhibitors ◽  
Binding Modes ◽  
Allosteric Inhibitors ◽  
Wide Range ◽  
Allosteric Sites ◽  
Protein Functions ◽  
Regulate Protein

: Allostery is an efficient and particular regulatory mechanism to regulate protein functions. Different from conserved orthosteric sites, allosteric sites have distinctive functional mechanism to form the complex regulatory network. In drug discovery, kinase inhibitors targeting the allosteric pockets have received extensive attention for the advantages of high selectivity and low toxicity. The approval of trametinib as the first allosteric inhibitor validated that allosteric inhibitors could be used as effective therapeutic drugs for treatment of diseases. To date, a wide range of allosteric inhibitors have been identified. In this perspective, we outline different binding modes and potential advantages of allosteric inhibitors. In the meantime, the research processes of typical and novel allosteric inhibitors are described briefly in terms of structureactivity relationships, ligand-protein interactions and in vitro and in vivo activity. Additionally, challenges as well as opportunities are presented.

iTSP-PseAAC: Identify Tumor Suppressor Proteins by Using Fully Connected Neural Network and PseAAC

2021 ◽  
Vol 15 ◽  
Author(s):  
Muhammad Awais ◽  
Waqar Hussain ◽  
Nouman Rasool ◽  
Yaser Daanial Khan
Keyword(s):  
Tumor Suppressor ◽  
Cross Validation ◽  
Control Cell ◽  
Normal Function ◽  
In Vivo Studies ◽  
Tumor Suppressor Proteins ◽  
Proposed Model ◽  
Self Consistency

Background: The uncontrolled growth due to accumulation of genetic and epigenetic changes as a result of loss or reduction in the normal function of Tumor Suppressor Genes (TSGs) and Pro-oncogenes is known as cancer. TSGs control cell division and growth by repairing of DNA mistakes during replication and restrict the unwanted proliferation of a cell or activities, those are the part of tumor production. Objectives: This study aims to propose a novel, accurate, user-friendly model to predict tumor suppressor proteins, which would be freely available to experimental molecular biologists to assist them using in vitro and in vivo studies. Methods: The predictor model has used the input feature vector (IFV) calculated from the physicochemical properties of proteins based on FCNN to compute the accuracy, sensitivity, specificity, and MCC. The proposed model was validated against different exhaustive validation techniques i.e. self-consistency and cross-validation. Results: Using self-consistency, the accuracy is 99%, for cross-validation and independent testing has 99.80% and 100% accuracy respectively. The overall accuracy of the proposed model is 99%, sensitivity value 98% and specificity 99% and F1-score was 0.99. Conclusion: It concludes, the proposed model for prediction of the tumor suppressor proteins can predict the tumor suppressor proteins efficiently, but it still has space for improvements in computational ways as the protein sequences may rapidly increase, day by day.

Alkaloids as Anticancer Agents: A Review of Chinese Patents in Recent 5 Years

2020 ◽  
Vol 15 (1) ◽  
pp. 2-13 ◽  
Author(s):  
Hongyu Tao ◽  
Ling Zuo ◽  
Huanli Xu ◽  
Cong Li ◽  
Gan Qiao ◽  
...  
Keyword(s):  
Anticancer Activity ◽  
Anticancer Agents ◽  
Kinase Inhibitors ◽  
Protein Kinase Inhibitors ◽  
Cdk Inhibitors ◽  
Comprehensive Overview ◽  
P53 Expression ◽  
Study Results

Background: In recent years, many novel alkaloids with anticancer activity have been found in China, and some of them are promising for developing as anticancer agents. Objective: This review aims to provide a comprehensive overview of the information about alkaloid anticancer agents disclosed in Chinese patents, and discusses their potential to be developed as anticancer drugs used clinically. Methods: Anticancer alkaloids disclosed in Chinese patents in recent 5 years were presented according to their mode of actions. Their study results published on PubMed, and SciDirect databases were presented. Results: More than one hundred anticancer alkaloids were disclosed in Chinese patents and their mode of action referred to arresting cell cycle, inhibiting protein kinases, affecting DNA synthesis and p53 expression, etc. Conclusion: Many newly found alkaloids displayed potent anticancer activity both in vitro and in vivo, and some of the anticancer alkaloids acted as protein kinase inhibitors or CDK inhibitors possess the potential for developing as novel anticancer agents.

scholarly journals The impact of FGF19/FGFR4 signaling inhibition in antitumor activity of multi-kinase inhibitors in hepatocellular carcinoma

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hiroaki Kanzaki ◽  
Tetsuhiro Chiba ◽  
Junjie Ao ◽  
Keisuke Koroki ◽  
Kengo Kanayama ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Molecular Mechanisms ◽  
Kinase Inhibitors ◽  
Progression Free Survival ◽  
Erk Signaling ◽  
Enzyme Linked Immunosorbent Assay ◽  
Antitumor Effects ◽  
The Impact

AbstractFGF19/FGFR4 autocrine signaling is one of the main targets for multi-kinase inhibitors (MKIs). However, the molecular mechanisms underlying FGF19/FGFR4 signaling in the antitumor effects to MKIs in hepatocellular carcinoma (HCC) remain unclear. In this study, the impact of FGFR4/ERK signaling inhibition on HCC following MKI treatment was analyzed in vitro and in vivo assays. Serum FGF19 in HCC patients treated using MKIs, such as sorafenib (n = 173) and lenvatinib (n = 40), was measured by enzyme-linked immunosorbent assay. Lenvatinib strongly inhibited the phosphorylation of FRS2 and ERK, the downstream signaling molecules of FGFR4, compared with sorafenib and regorafenib. Additional use of a selective FGFR4 inhibitor with sorafenib further suppressed FGFR4/ERK signaling and synergistically inhibited HCC cell growth in culture and xenograft subcutaneous tumors. Although serum FGF19high (n = 68) patients treated using sorafenib exhibited a significantly shorter progression-free survival and overall survival than FGF19low (n = 105) patients, there were no significant differences between FGF19high (n = 21) and FGF19low (n = 19) patients treated using lenvatinib. In conclusion, robust inhibition of FGF19/FGFR4 is of importance for the exertion of antitumor effects of MKIs. Serum FGF19 levels may function as a predictive marker for drug response and survival in HCC patients treated using sorafenib.

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