scholarly journals ATX-101, a Peptide Targeting PCNA, Has Antitumor Efficacy Alone or in Combination with Radiotherapy in Murine Models of Human Glioblastoma

Cancers ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 289
Author(s):  
Giovanni Luca Gravina ◽  
Alessandro Colapietro ◽  
Andrea Mancini ◽  
Alessandra Rossetti ◽  
Stefano Martellucci ◽  
...  
Keyword(s):  
Single Agent ◽  
Nuclear Antigen ◽  
Human Glioblastoma ◽  
Akt Activation ◽  
Glioma Initiating Cells ◽  
Human Glioblastoma Multiforme ◽  
A Cell ◽  
Peptide Targeting ◽  
Proliferating Cell

Cell proliferation requires the orchestrated actions of a myriad of proteins regulating DNA replication, DNA repair and damage tolerance, and cell cycle. Proliferating cell nuclear antigen (PCNA) is a master regulator which interacts with multiple proteins functioning in these processes, and this makes PCNA an attractive target in anticancer therapies. Here, we show that a cell-penetrating peptide containing the AlkB homolog 2 PCNA-interacting motif (APIM), ATX-101, has antitumor activity in a panel of human glioblastoma multiforme (GBM) cell lines and patient-derived glioma-initiating cells (GICs). Their sensitivity to ATX-101 was not related to cellular levels of PCNA, or p53, PTEN, or MGMT status. However, ATX-101 reduced Akt/mTOR and DNA-PKcs signaling, and a correlation between high Akt activation and sensitivity for ATX-101 was found. ATX-101 increased the levels of γH2AX, DNA fragmentation, and apoptosis when combined with radiotherapy (RT). In line with the in vitro results, ATX-101 strongly reduced tumor growth in two subcutaneous xenografts and two orthotopic GBM models, both as a single agent and in combination with RT. The ability of ATX-101 to sensitize cells to RT is promising for further development of this compound for use in GBM.

scholarly journals Lomeguatrib Increases the Radiosensitivity of MGMT Unmethylated Human Glioblastoma Multiforme Cell Lines

2021 ◽  
Vol 22 (13) ◽  
pp. 6781
Author(s):  
Anna Kirstein ◽  
Daniela Schilling ◽  
Stephanie E. Combs ◽  
Thomas E. Schmid
Keyword(s):  
Glioblastoma Multiforme ◽  
Cell Lines ◽  
Dna Methyltransferase ◽  
Treatment Options ◽  
Treatment Resistance ◽  
Cell Cycle Distribution ◽  
Human Glioblastoma ◽  
Human Glioblastoma Multiforme ◽  
Mgmt Protein

Background: Treatment resistance of glioblastoma multiforme to chemo- and radiotherapy remains a challenge yet to overcome. In particular, the O6-methylguanine-DNA-methyltransferase (MGMT) promoter unmethylated patients have only little benefit from chemotherapy treatment using temozolomide since MGMT counteracts its therapeutic efficacy. Therefore, new treatment options in radiotherapy need to be developed to inhibit MGMT and increase radiotherapy response. Methods: Lomeguatrib, a highly specific MGMT inhibitor, was used to inactivate MGMT protein in vitro. Radiosensitivity of established human glioblastoma multiforme cell lines in combination with lomeguatrib was investigated using the clonogenic survival assay. Inhibition of MGMT was analyzed using Western Blot. Cell cycle distribution and apoptosis were investigated to determine the effects of lomeguatrib alone as well as in combination with ionizing radiation. Results: Lomeguatrib significantly decreased MGMT protein and reduced radiation-induced G2/M arrest. A radiosensitizing effect of lomeguatrib was observed when administered at 1 µM and increased radioresistance at 20 µM. Conclusion: Low concentrations of lomeguatrib elicit radiosensitization, while high concentrations mediate a radioprotective effect.

scholarly journals An evaluation of antioxidant effects on recovery from postischemic acute renal failure.

1994 ◽  
Vol 4 (8) ◽  
pp. 1588-1597
Author(s):  
R A Zager ◽  
S M Fuerstenberg ◽  
P H Baehr ◽  
D Myerson ◽  
B Torok-Storb
Keyword(s):  
Renal Failure ◽  
Acute Renal Failure ◽  
Dna Fragmentation ◽  
Proliferating Cell Nuclear Antigen ◽  
Antigen Expression ◽  
Nuclear Antigen ◽  
Terminal Deoxynucleotidyl Transferase ◽  
Tubular Necrosis ◽  
Proliferating Cell

Xanthine oxidase (XO) activity and hydroxyl radical (.OH) formation are widely proposed mediators of renal reperfusion injury, potentially altering the severity of, and recovery from, postischemic acute renal failure. The goal of this study was to ascertain whether combination XO inhibitor (oxypurinol) and .OH scavenger (Na benzoate) therapy, given at the time of renal ischemia, alters the extent of: (1) tubular necrosis and filtration failure; (2) DNA fragmentation/apoptosis (assessed in situ by terminal deoxynucleotidyl transferase reactivity); (3) early tubular regenerative responses (proliferating cell nuclear antigen expression; (3H)thymidine incorporation); and (4) the rate and/or degree of functional and morphologic repair. The effects of XO inhibition, .OH scavengers, and "catalytic" iron (FeSO4) on human proximal tubular cell proliferation in vitro were also assessed with a newly established cell line (HK-2). Male Sprague-Dawley rats were subjected to 35 min of bilateral renal arterial occlusion with or without oxypurinol/benzoate therapy. These agents did not alter the extent of tubular necrosis or filtration failure, proliferating cell nuclear antigen expression or thymidine incorporation, or the rate/extent of renal functional/morphologic repair. DNA fragmentation did not precede tubular necrosis, and it was unaffected by antioxidant therapy. By 5 days postischemia, both treatment groups demonstrated regenerating epithelial fronds that protruded into the lumina. These structures contained terminal deoxynucleotidyl transferase-reactive, but morphologically intact, cells, suggesting the presence of apoptosis. Oxypurinol and .OH scavengers (benzoate; dimethylthiourea) suppressed in vitro tubular cell proliferation; conversely, catalytic Fe had a growth-stimulatory effect. These results suggest that: (1) XO inhibition/.OH scavenger therapy has no discernible net effect on postischemic acute renal failure; (2) DNA fragmentation does not precede tubular necrosis, suggesting that it is not a primary mediator of ischemic cell death; and (3) antioxidants can be antiproliferative for human tubular cells, possibly mitigating their potential beneficial effects.

Involvement of proliferating cell nuclear antigen (cyclin) in DNA replication in living cells

1989 ◽  
Vol 9 (1) ◽  
pp. 57-66
Author(s):  
M Zuber ◽  
E M Tan ◽  
M Ryoji
Keyword(s):  
Dna Polymerase ◽  
Proliferating Cell Nuclear Antigen ◽  
Living Cells ◽  
Nuclear Antigen ◽  
Plasmid Replication ◽  
Dna Polymerase Delta ◽  
Dna Polymerase Alpha ◽  
Proliferating Cell

Proliferating cell nuclear antigen (PCNA) (also called cyclin) is known to stimulate the activity of DNA polymerase delta but not the other DNA polymerases in vitro. We injected a human autoimmune antibody against PCNA into unfertilized eggs of Xenopus laevis and examined the effects of this antibody on the replication of injected plasmid DNA as well as egg chromosomes. The anti-PCNA antibody inhibited plasmid replication by up to 67%, demonstrating that PCNA is involved in plasmid replication in living cells. This result further implies that DNA polymerase delta is necessary for plasmid replication in vivo. Anti-PCNA antibody alone did not block plasmid replication completely, but the residual replication was abolished by coinjection of a monoclonal antibody against DNA polymerase alpha. Anti-DNA polymerase alpha alone inhibited plasmid replication by 63%. Thus, DNA polymerase alpha is also required for plasmid replication in this system. In similar studies on the replication of egg chromosomes, the inhibition by anti-PCNA antibody was only 30%, while anti-DNA polymerase alpha antibody blocked 73% of replication. We concluded that the replication machineries of chromosomes and plasmid differ in their relative content of DNA polymerase delta. In addition, we obtained evidence through the use of phenylbutyl deoxyguanosine, an inhibitor of DNA polymerase alpha, that the structure of DNA polymerase alpha holoenzyme for chromosome replication is significantly different from that for plasmid replication.

scholarly journals A Novel Gold Calreticulin Nanocomposite Based on Chitosan for Wound Healing in a Diabetic Mice Model

Nanomaterials ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 75 ◽  
Author(s):  
Sara Paola Hernández Martínez ◽  
Teodoro Iván Rivera González ◽  
Moisés Armides Franco Molina ◽  
Juan José Bollain y Goytia ◽  
Juan José Martínez Sanmiguel ◽  
...  
Keyword(s):  
Wound Healing ◽  
Topical Administration ◽  
Nuclear Antigen ◽  
Histological Evaluation ◽  
Mice Model ◽  
Fibroblast Migration ◽  
And Migration ◽  
Proliferating Cell

The development of new nanomaterials to promote wound healing is rising, because of their topical administration and easy functionalization with molecules that can improve and accelerate the process of healing. A nanocomposite of gold nanoparticles (AuNPs) functionalized with calreticulin was synthetized and evaluated. The ability of the nanocomposite to promote proliferation and migration was determined in vitro, and in vivo wound healing was evaluated using a mice model of diabetes established with streptozotocin (STZ). In vitro, the nanocomposite not affect the cell viability and the expression of proliferating cell nuclear antigen (PCNA). Moreover, the nanocomposite promotes the clonogenicity of keratinocytes, endothelial cells, and fibroblasts, and accelerates fibroblast migration. In vivo, mice treated with the nanocomposite presented significantly faster wound healing. The histological evaluation showed re-epithelization and the formation of granular tissue, as well as an increase of collagen deposition. Therefore, these results confirm the utility of AuNPs–calreticulin nanocomposites as potential treatment for wound healing of diabetic ulcers.

Identification of the functional domain of p21WAF1/CIP1 that protects cells from cisplatin cytotoxicity

2005 ◽  
Vol 289 (3) ◽  
pp. F514-F520 ◽  
Author(s):  
Fang Yu ◽  
Judit Megyesi ◽  
Robert L. Safirstein ◽  
Peter M. Price
Keyword(s):  
Dominant Negative ◽  
Nuclear Antigen ◽  
Functional Domain ◽  
Binding Domains ◽  
Cdk2 Activity ◽  
Localization Signal ◽  
Induced Apoptosis ◽  
Proliferating Cell

The p21 cyclin-dependent kinase (cdk) inhibitor protects cells from cisplatin cytotoxicity in vivo and in vitro. However, the mechanism of protection is not known. Separate p21 domains are known to interact with several different proteins having proapoptotic functions. To investigate the mechanism of protection by p21, we have constructed adenoviruses encoding the different domains of p21. We were able to localize the protective activity to a region of 54 amino acids containing the cyclin-cdk interacting moiety. Other protein binding domains of p21, including the NH2-terminal procaspase-3 interactive region and the COOH-terminal region containing the proliferating cell nuclear antigen binding domain and the nuclear localization signal, had little protective effect on cisplatin cytotoxicity. The dependence of cisplatin cytotoxicity on cdk2 activity was also demonstrated because 1) cisplatin caused a marked increase in cdk2 activity, which was prevented by the p21 expression adenovirus, and 2) a cdk2 dominant-negative adenovirus also protected cells from cisplatin-induced apoptosis. Thus the data suggest that the mechanism of p21 protection is by direct inhibition of cdk2 activity and that cisplatin-induced apoptosis is caused by a cdk2-dependent pathway.

scholarly journals TRIM28 functions as the SUMO E3 ligase for PCNA in prevention of transcription induced DNA breaks

2020 ◽  
Vol 117 (38) ◽  
pp. 23588-23596
Author(s):  
Min Li ◽  
Xiaohua Xu ◽  
Chou-Wei Chang ◽  
Yilun Liu
Keyword(s):  
Rna Polymerase Ii ◽  
Proliferating Cell Nuclear Antigen ◽  
E3 Ligase ◽  
Nuclear Antigen ◽  
Dna Breaks ◽  
Interacting Protein ◽  
Proteomic Approach ◽  
Sumo E3 Ligase ◽  
Proliferating Cell

In human cells, the DNA replication factor proliferating cell nuclear antigen (PCNA) can be conjugated to either the small ubiquitinlike modifier SUMO1 or SUMO2, but only SUMO2-conjugated PCNA is induced by transcription to facilitate resolution of transcription–replication conflict (TRC). To date, the SUMO E3 ligase that provides substrate specificity for SUMO2-PCNA conjugation in response to TRC remains unknown. Using a proteomic approach, we identified TRIM28 as the E3 ligase that catalyzes SUMO2-PCNA conjugation. In vitro, TRIM28, together with the RNA polymerase II (RNAPII)-interacting protein RECQ5, promotes SUMO2-PCNA conjugation but inhibits SUMO1-PCNA formation. This activity requires a PCNA-interacting protein (PIP) motif located within the bromodomain of TRIM28. In cells, TRIM28 interaction with PCNA on human chromatin is dependent on both transcription and RECQ5, and SUMO2-PCNA level correlates with TRIM28 expression. As a consequence, TRIM28 depletion led to RNAPII accumulation at TRC sites, and expression of a TRIM28 PIP mutant failed to suppress TRC-induced DNA breaks.

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