bims-midomi 2025-12-07 papers

PLoS One. 2025 ;20(12): e0320036

Characterization of p53 p.T253I as a pathogenic mutation underlying Li-Fraumeni Syndrome.

Nathaniel C Holcomb, Amanda M Harrington, Hong Pu, Berina Halilovic, Nathan R Shelman, Shulin Zhang, Catherine Sears, Terra Armstrong, Brent Shelton, Lauren Corum, John A D'Orazio.

We identified a germline TP53 c.758C > T (p.T253I) mutation in the TP53 tumor suppressor gene in a pediatric adrenocortical carcinoma (ACC) patient. Characteristic of pathogenic p53 mutations, we observed upregulation of total p53 protein levels in the patient's ACC and concurrent suppression of the wild-type (WT) TP53 allele. As ACC can be associated with Li-Fraumeni Syndrome (LFS) and the mutation has not yet been linked to LFS, we sought to characterize the functionality of the T253I mutation. We acquired p53-/- HEK293 cells and stably transduced them with GFP-tagged wild type (T253) or T253I p53 as well as two established pathogenic p53 mutants (C176Y and R213X). Compared to p53 WT, levels of T253I p53 increased while MDM2 levels decreased, suggesting a loss of MDM2-mediated regulation of T253I p53. Additionally, T253I showed a reduction in DNA damage responsive events, diminished DNA binding capabilities, and blunted transactivation capacity. These experimental data lead us to conclude that T253I represents a pathologic variant in TP53 that may predispose to LFS-associated tumors.

DOI: https://doi.org/10.1371/journal.pone.0320036

Bioorg Med Chem. 2025 Nov 21. pii: S0968-0896(25)00433-X. [Epub ahead of print]133 118492

Screening of one-bead one-compound cyclic peptide libraries using unpurified proteins from the wheat germ cell-free system to identify protein-protein interaction inhibitors.

Miki Hasegawa, Akira Nozawa, Yoshihito Tanaka, Kohki Kido, Shinichi Terawaki, Chikako Takahashi, Yasumasa Matsumoto, Yuichi Onda, Kouhei Tanaka, Taro Kishimoto, Hiroshi Sato, Akihiro Takemiya, Tatsuya Sawasaki.

Protein-protein interactions (PPIs) are recognized as both attractive and challenging therapeutic targets. Cyclic peptides are particularly well-suited for PPI inhibition due to their ability to effectively interfere with the extensive surface areas involved in these interactions. One-Bead One-Compound (OBOC) libraries have been widely utilized in affinity-based on-bead screening approaches to identify cyclic peptides targeting PPIs. However, a major bottleneck in OBOC library screening is the requirement for purified proteins to ensure screening accuracy. In this study, we present a novel screening platform that integrates an OBOC cyclic peptide library with crude bait proteins produced using a wheat germ cell-free system, eliminating the need for a purification step. This approach facilitates drug discovery for biologically relevant target proteins and those that are difficult to purify. To demonstrate the effectiveness of this method, we selected the p53-murine double minute 2 (MDM2) interaction as a model target and performed a large-scale on-bead binding assay using MDM2. The primary hits identified through this screening exhibited PPI inhibitory activity in the AlphaScreen assay, and docking simulations further verified their binding mode to MDM2. This method offers an efficient strategy for screening cyclic peptides against challenging drug targets, expanding opportunities for PPI-targeted drug discovery.

Keywords: AlphaScreen; Cyclic peptides; One-Bead One-Compound library; Protein-protein interactions; Unpurified proteins; Wheat germ cell-free synthesized proteins; p53-MDM2

DOI: https://doi.org/10.1016/j.bmc.2025.118492

Phys Chem Chem Phys. 2025 Dec 01.

Azurin-based peptide p28 disrupts p53-HDM2 interactions: insights from in silico studies.

Albin Joy, Anand Srivastava, Rajib Biswas.

This study investigates the potential anticancer activity of the azurin-derived peptide p28 through its molecular interactions with human double minute 2 (HDM2), a key negative regulator of the tumor suppressor protein p53. By binding to the p53 transactivation domain, HDM2 impairs p53's tumor-suppressive functions. Using the information-driven docking platform HADDOCK, we generated ten plausible binding poses of p28 with the HDM2 N-terminal domain. Each pose was subsequently refined via three independent 300 ns all-atom molecular dynamics simulations, resulting in a cumulative 9 µs trajectory. Although this workflow does not capture spontaneous binding or pose interconversion, it enables systematic refinement and stability assessment of docking-generated complexes. From this analysis, three stable conformations (D3, D4, and D5) have emerged, consistently occupying the HDM2 hydrophobic pocket and exhibiting favorable binding energies (MMPBSA). Residue-level interaction analysis revealed that p28 engages HDM2 hotspots important for p53 recognition, suggesting a competitive mode of binding. While experimental studies and enhanced sampling simulations are required to fully validate these findings, our results provide a refined structural basis for understanding how p28 may interfere with HDM2-p53 interactions and support its promise as a peptide-based anticancer candidate.

DOI: https://doi.org/10.1039/d5cp02358k

Biomed Pharmacother. 2025 Dec 04. pii: S0753-3322(25)01062-5. [Epub ahead of print]193 118868

Balancing cell cycle arrest and immune activation: A synergistic window for idasanutlin and anti-PD-1 therapy in a syngeneic mouse model.

Aneta Nieznanska, Malgorzata Statkiewicz, Zuzanna Sandowska-Markiewicz, Katarzyna Unrug-Bielawska, Alicja Majewska, Justyna Kocik-Krol, Marcin Czepiel, Adrianna Galuszka-Bulaga, Michal Mikula, Jerzy Ostrowski, Tad A Holak, Lukasz Skalniak.

Recent studies have explored combining MDM2 antagonists with immunotherapy. Here, we assessed the effect of anti-PD-1 and idasanutlin co-treatment in a syngeneic CT26/BALB/c mouse model. Prior to in vivo testing, idasanutlin's activity was evaluated in three murine cell lines (B16-F10, CT26, MC38), revealing varied responses linked to p53 status. Compared to human U-2 OS cells, p53-wild-type mouse cells showed weaker but specific responses, including increased p53/p21 expression, reduced viability, and cell cycle arrest. Due to limited efficacy in murine cells, idasanutlin was tested at three doses in vivo. Surprisingly, the lowest dose (50 mg/kg) produced the highest synergistic effect with anti-PD-1 treatment, significantly reducing tumor size. Higher doses (100 and 200 mg/kg) and anti-PD-1 monotherapy provided either no or only limited tumor size reduction. High doses of idasanutlin decreased the proliferation of T cells and depleted T cell numbers within the lymphocyte population, as we show in vitro and in vivo. These findings suggest that low doses of MDM2 antagonists may enhance immunotherapy, while higher doses could interfere with immunotherapy by p53-mediated cell cycle arrest and decreasing the proliferation of the immune cells.

Keywords: Cancer immunotherapy; Combination therapy; Dose-dependent synergy; Idasanutlin; MDM2 antagonist; PD-1 blockade; RG7388; Syngeneic mouse model

DOI: https://doi.org/10.1016/j.biopha.2025.118868

PLoS One. 2025 ;20(12): e0337568

Exposure to polystyrene nanoparticles induce disruption of mitochondrial homeostasis and impairs trophoblast cell invasion and migration via MDM2/ROCK1 pathway.

Dongdong Hao, Tengteng Ma, Xiaoping Li, Fengchun Gao.

BACKGROUND: Polystyrene nanoparticles (PS-NPs) are recognized as environmental pollutants with potential reproductive toxicity. This study delves into the impacts of PS-NPs exposure on trophoblast cells, specifically examining mitochondrial dysfunction, cell invasion and migration.
METHODS: Trophoblast cells were exposed to PS-NPs to evaluate the effects on cell proliferation, apoptosis, mitochondrial function (including mitochondrial membrane potential, intracellular ROS levels, and gene expression), autophagy, inflammatory responses and cell motility. Co-immunoprecipitation and Western blotting analyses were employed to assess the expressions and interactions of MDM2 and ROCK1 under PS-NPs exposure conditions.
RESULTS: We observed that PS-NPs exposure impaired trophoblast cell proliferation, promoted apoptosis, and disrupted mitochondrial function, evident by ROS elevation, mitochondrial membrane potential reduction, and altered gene expression. Increased autophagy activity and inflammatory cytokine release indicated cellular stress. Moreover, PS-NPs impeded cell migration and invasion, with exacerbated effects upon MDM2 knockdown and ROCK1 inhibition.
CONCLUSION: The study elucidates the intricate connections among mitochondrial dysfunction, autophagy, inflammation, and cell motility in response to PS-NPs, suggesting that targeting the MDM2-ROCK1 pathway could offer a promising approach to alleviate PS-NP-induced toxicity in trophoblast cells and support placental health.

DOI: https://doi.org/10.1371/journal.pone.0337568