P53 Inhibitor Research Articles

CUL4B protects kidneys from acute injury by restraining p53/PAI-1 signaling

Acute kidney injury (AKI) caused by nephrotoxins, ischemia reperfusion (IR) or sepsis is associated with high morbidity and mortality. Unveiling new mechanisms underlying AKI can help develop new therapeutic strategy. Cullin 4B (CUL4B) is a scaffold protein in the CUL4B-RING E3 ubiquitin ligase (CRL4B) complex. Here, we demonstrate that CUL4B can protect kidneys from acute injury induced by cisplatin and IR. CUL4B is upregulated in mouse tubular epithelial cells (TECs) after cisplatin treatment or IR. Loss of CUL4B in kidneys exacerbates renal injury, inflammation, and apoptosis of TECs caused by cisplatin and IR. Transcriptome analysis reveals that Cul4b deficiency enhances injury-induced PAI-1 expression. CUL4B suppresses PAI-1 expression by promoting polyubiquitination and degradation of p53. Inhibition of either PAI-1 or p53 can prevent the aggravated renal injury and inflammation caused by loss of CUL4B. Our work has identified the kidney-protective role of CUL4B against acute injury.

Gambogic acid induces GSDME dependent pyroptotic signaling pathway via ROS/P53/Mitochondria/Caspase-3 in ovarian cancer cells

Gambogic acid (GA) is a naturally active compound extracted from the Garcinia hanburyi with various anticancer activities. However, whether GA induces pyroptosis (a newly discovered inflammation-mediated programmed cell death mechanism) in ovarian cancer (OC) has not yet been reported. This study revealed that GA treatment reduced cell viability by inducing pyroptosis in OC cell lines. Typical pyroptosis morphological manifestations such as cell swelling with large bubbles and loss of cell membrane integrity, were observed. Cleaved caspase-3 and GSDME-N levels increased after GA treatment, and knocking out GSDME or using a caspase-3 inhibitor could switch GA-induced cell death from pyroptosis to apoptosis, indicating GA induced caspase-3/GSDME-dependent pyroptosis. Furthermore, this research indicated that GA significantly increased reactive oxygen species (ROS) and p53 phosphorylation. OC cells pretreated with ROS inhibitor N-Acetylcysteine (NAC) and the specific p53 inhibitor pifithrin-μ could completely reverse the pyroptosis post-treatment. Elevated p53 and phosphorylated p53 reduced mitochondrial membrane potential (MMP) and Bcl-2, increase the expression of Bax, and damage mitochondria by releasing cytochrome c to activate the downstream pyroptosis pathway. Different doses of GA inhibited tumor growth in ID8 tumor-bearing mice, and high-dose GA increased in tumor-infiltrating lymphocytes CD3, CD4, and CD8 were detected in tumor tissues. Notably, the expressions of GSDME-N, cleaved caspase-3 and other proteins were increased in tumor tissues with high-dose GA groups. These findings demonstrate that GA-treated OC cells could induce GSDME-mediated pyroptosis through the ROS/p53/mitochondria signaling pathway and caspase-3/-9 activation. Thus, GA is a promising therapeutic agent for OC treatment

Loss of Brcc3 in Zebrafish Embryos Increases Their Susceptibility to DNA Damage Stress.

DNA double-strand breaks (DSBs) represent one of the most severe forms of genetic damage in organisms, yet vertebrate models capable of monitoring DSBs in real-time remain scarce. BRCA1/BRCA2-containing complex subunit 3 (BRCC3), also known as BRCC36, functions within various multiprotein complexes to mediate diverse biological processes. However, the physiological role of BRCC3 in vertebrates, as well as the underlying mechanisms that govern its activity, are not well understood. To explore these questions, we generated brcc3-knockout zebrafish using CRISPR/Cas9 gene-editing technology. While brcc3 mutant zebrafish appear phenotypically normal and remain fertile, they exhibit significantly increased rates of mortality and deformity following exposure to DNA damage. Furthermore, embryos lacking Brcc3 display heightened p53 signaling, elevated γ-H2AX levels, and increased apoptosis in response to DNA-damaging agents such as ultraviolet (UV) light and Etoposide (ETO). Notably, genetic inactivation of p53 or pharmacological inhibition of Ataxia-telangiectasia mutated (ATM) activity rescues the hypersensitivity to UV and ETO observed in Brcc3-deficient embryos. These findings suggest that Brcc3 plays a critical role in DNA damage response (DDR), promoting cell survival during embryogenesis. Additionally, brcc3-null mutant zebrafish offer a promising vertebrate model for real-time monitoring of DSBs.

TMOD-19. GERMLINEELP1 DEFICIENCY SENSITIZES CEREBELLAR GRANULE NEURON PROGENITORS TO SHH MEDULLOBLASTOMA

Abstract Germline loss-of-function (LOF) variants in Elongator complex protein 1 (ELP1) are the most prevalent predisposing genetic events observed in medulloblastoma (MB), accounting for 30% of the Sonic Hedgehog 3 subtype (SHH-3). Molecularly, ELP1-associated SHH-MBs acquire somatic PTCH1 mutations in >80% of cases, and universal loss-of-heterozygosity of the wild-type ELP1 and PTCH1 alleles through loss of chromosome-arm 9q, resulting in their biallelic inactivation. Notably, germline ELP1 LOF occurs mutually exclusive with somatic/germline TP53 mutations in the SHH-3 subtype, suggesting that genetic perturbation of either ELP1 or TP53 may promote similar downstream oncogenic consequences in cerebellar granule neuron progenitors (GNPs), the accepted cellular origin of SHH-MB. Despite these findings, the molecular, biochemical, and cellular mechanism(s) by which ELP1-deficiency provokes malignant pathogenesis remain unknown. In this study, we sought to close this knowledge gap and functionally determine why children harboring pathogenic ELP1 germline variants are at an increased risk of developing SHH-MB. Mice were genetically engineered to mimic heterozygous Elp1 LOF (Elp1HET). We studied the effect of loss of ELP1 in GNPs using a combination of molecular profiling, immunophenotyping, and cellular assays. GNPs from Elp1HET exhibited a spectrum of molecular and biochemical hallmarks of malignant transformation including increased DNA replication stress, DNA damage, accelerated cell cycle progression, and stalled differentiation. Orthotopic transplantation of Elp1HET GNPs engineered to harbor somatic Ptch1 inactivation yielded SHH-MB-like tumors with compromised p53 signaling, providing an explanation for the specificity of ELP1-associated tumors in SHH-3, and their exclusivity with TP53-mutant tumors. Treatment of ELP1-mutant patient-derived xenografts with an FDA-approved MDM2 inhibitor reactivated p53-dependent apoptosis and extended survival. Collectively, our findings functionally substantiate the role of ELP1 deficiency in predisposition to SHH-3 MB and nominate therapeutic strategies to overcome p53 inhibition as a rational treatment option.

P300 Maintains Primordial Follicle Activation by Repressing VEGFA Transcription.

During the reproductive life, most primordial follicles remain dormant for years or decades, while some are progressively activated for development. Misactivation of primordial follicles can cause ovarian diseases, for example, premature ovarian insufficiency (POI). Our results show that p300 expression increased with primordial follicle activation. Using a p300 inhibitor resulted in premature activation of primordial follicles in cultured mouse ovaries. Conversely, the ratio of primordial follicle activation was markedly decreased upon culturing with the p300 agonist. Furthermore, p300 regulated primordial follicle activation by inhibiting Vegfa transcription in granulosa cells. Additionally, this study was extended to potential clinical applications, showing that short-term treatment with a p300 inhibitor in vitro significantly increased primordial follicle activation in newborn mouse ovaries after dorsal kidney membrane transplantation in female NSG mice. Our results revealed that p300 controls the activation of primordial follicles in mammalian ovaries.

EZH2 inhibition or genetic ablation suppresses cyst growth in autosomal dominant polycystic kidney disease

BackgroundAutosomal Dominant Polycystic Kidney Disease (ADPKD) is a prevalent genetic disorder characterized by the formation of renal cysts leading to kidney failure. Despite known genetic underpinnings, the variability in disease progression suggests additional regulatory layers, including epigenetic modifications.MethodsWe utilized various ADPKD models, including Pkd1 and Ezh2 conditional knockout (Pkd1delta/delta:Ezh2delta/delta) mice, to explore the role of Enhancer of Zeste Homolog 2 (EZH2) in cystogenesis. Pharmacological inhibition of EZH2 was performed using GSK126 or EPZ-6438 across multiple models.ResultsEZH2 expression was significantly upregulated in Pkd1−/− cells, Pkd1delta/delta mice, and human ADPKD kidneys. EZH2 inhibition attenuates cyst development in MDCK cells and a mouse embryonic kidney cyst model. Both Ezh2 conditional knockout and GSK126 treatment suppressed renal cyst growth and protected renal function in Pkd1delta/delta mice. Mechanistically, cAMP/PKA/CREB pathway increased EZH2 expression. EZH2 mediated cystogenesis by enhancing methylation and activation of STAT3, promoting cell cycle through p21 suppression, and stimulating non-phosphorylated β-catenin in Wnt signaling pathway. Additionally, EZH2 enhanced ferroptosis by inhibiting SLC7A11 and GPX4 in ADPKD.ConclusionOur findings elucidate the pivotal role of EZH2 in promoting renal cyst growth through epigenetic mechanisms and suggest that EZH2 inhibition or ablation may serve as a novel therapeutic approach for managing ADPKD.

Restoration of autophagy reduces diabetes-induced endothelial dysfunction

Abstract Introduction Diabetes leads to endothelial dysfunction, a main determinant of several cardiovascular diseases. The molecular mechanisms underlying the effects of hyperglycemia in endothelial cells are not fully characterized. Autophagy, the intracellular process by which the cell digests and recycles senescent or damaged cytoplasmic elements, exerts cardiovascular protective effects, limiting cardiac and vascular injury in the presence of stress. However, it is unclear how hyperglycemia modulates autophagy in endothelial cells. Purpose In this study, we elucidated the role of autophagy in vascular damage induced by diabetes. We also tested whether the restoration autophagy attenuates diabetes-induced endothelial damage. Methods We evaluated the effects of high-glucose (HG, 30 mM for 6 and 24 hours) on markers of endothelial function, autophagy, autophagic flux, and mitophagy in human umbilical endothelial cells (HUVEC) in vitro and in mesenteric arteries from wild-type mice (WT) ex vivo. We tested the effects of autophagy reactivation using the natural polyamine spermidine or ATG7 overexpression (ATG7ov) on apoptosis and angiogenesis in HUVEC treated with HG. Vascular reactivity experiments in the presence of autophagy activation were performed in HG-treated mouse mesenteric arteries and human saphenous veins from patients with peripheral artery disease. Finally, we evaluated the level of autophagy in the mammary arteries of newly discovered diabetic patients undergoing coronary artery bypass graft surgery. Results We found that HG reduces autophagy (0.6 fold p<0.05) and mitophagy (1.5 fold p<0.001) in HUVECs. We also demonstrated that endothelial cells undergoing hyperglycemia fail to activate autophagy under hypoxic conditions (0.6 fold p<0.05). Reactivation of autophagy by ATG7ov rescues apoptosis (0.52 fold p<0.05) and angiogenesis (2.3 fold p<0.05) in HUVEC treated with HG. We further observed that HG exacerbates endothelial dysfunction in a mouse model of genetic inhibition (Beclin 1 +/- mice), compared to WT mice (-19.16 % +-4.97 SEM vs -48.39 % +-2.18 SEM p<0.001). Mechanistically, HG increases cellular acetylation status (0.7 fold p<0.05) and activates p300 (1 fold p<0.05), an autophagy inhibitor. ATG7ov or spermidine, a p300 inhibitor, rescue endothelial-dependent relaxation in mesenteric arteries of WT mice treated with HG (ATG7ov -62.48 % +-5.16 SEM; SP -63.01 +-3.22 SEM; HG -40.67 % +-3.82 p<0.001). Finally, we observed reduced levels of autophagy in mammary arteries from diabetic patients and demonstrated that SP improves vascular function in human saphenous veins (-37.6 % +-12.76 SEM vs -12.52 % +-5.6 SEM p<0.001). Conclusion Our results suggest that the impairment of autophagy is a strong contributor of diabetes induced-endothelial dysfunction. Targeting autophagy may represent a valid therapeutic strategy to counteract the cardiovascular consequences of metabolic stress.

Modulation of p300 acetylation to protect against doxorubicin-induced cardiotoxicity

Abstract Background Doxorubicin (DOX) is a widely-used anti-neoplastic agent, but the most common adverse reaction to its use is cardiotoxicity(1). DOX acts by producing reactive oxygen species (ROSs) that cause DNA damage(1,2), which activates various proteins, including the tumour suppressor p53 and the acetyltransferase p300. When activated, p300 acetylates and increases the activity of p53 which leads to increased apoptotic activity(3). Cardiotoxicity results because the heart has limited mechanisms to dispose of ROSs(4), and because cardiomyocytes have a low turnover rate(5). Purpose We examined the p300 inhibitor Theracurmin (THR)(6,7) as a candidate to prevent DOX cardiotoxicity using an in-vivo mouse model, and sought to elucidate the underlying molecular mechanisms using in-vitro studies. Methods C57BL/6 mice were pre-treated with THR or vehicle (as control), then administered DOX or vehicle. Cardiac function was evaluated by echocardiography and cardiac catheterization. In vitro studies used cardiac fibroblasts (FBs) and cardiac endothelial cells (ECs) pre-treated with THR, then with DOX, as in the animal studies. Western blotting and rt-qPCR was used to quantify protein and mRNA levels of genes in the p53-p300 pathway or related to apoptosis, oxidative stress, and cell cycle control. Results DOX-treated mice showed significant decreases in left ventricular (LV) ejection fraction (LVEF, p=0.0004), fractional shortening (FS, p=0.0012), and a significant increase in end-systolic volume (ESV, p=0.0004). We also showed a significant decrease in anterior (LVAW;d, p=0.005) and posterior (LVPW;d, p=0.005) wall thickness of the LV in these mice. However, when mice were pre-treated with THR prior to DOX administration, we saw significant increases in LVEF (p=0.045) and LVPW;d (p=0.015), and a significant decrease in ESV (p=0.0047) compared to those that were not pre-treated. In-vitro analyses demonstrated a significant increase in cleaved caspase 3 protein expression in DOX-treated ECs (p=0.007), that was not prevented by THR pre-treatment. In DOX-treated FBs, we saw a reduction in AKT mRNA (p=0.017) and increases in BAX 9p=0.008), P21 (p=0.0001), and GADD45 (0.037) mRNA expression. In DOX-treated ECs, we also saw significant increases in BAX (p=0.015) and P21 (p=0.011) mRNA expression. These changes in mRNA expression were not reversed with THR pre-treatment in either cell type. Conclusion THR pre-treatment successfully mitigated functional deficits and structural deficits associated with DOX cardiotoxicity. In-vitro studies show that THR pre-treatment was not sufficient to significantly prevent changes in key molecular targets associated with apoptosis. Further studies are required to elucidate the mechanism behind the observed functional changes.Abstract OverviewAbstract Results

TP53 Codon 72 Polymorphism Impacts Macrophage Activation through Reactive Oxygen Species-Dependent Cell Signaling Alterations.

The role of the most common TP53 single-nucleotide polymorphism (SNP) at codon 72, which encodes for proline (P72) or arginine (R72), in the regulation of the immune system has not yet been thoroughly explored. We found that this SNP contributes to aggravated inflammatory response in COVID-19 patients resulting from biased macrophage activation. R72-P53 inhibits mitochondrial manganese superoxide dismutase, leading to impaired reactive oxygen species scavenging, oxidation of phosphatase and tensin homolog deleted on chromosome 10 (PTEN), and, consequently, its inhibition. Reduced PTEN activity causes constitutive activation of the PI3K/Akt pathway, which restricts proinflammatory (M1) and promotes anti-inflammatory (M2) phenotypes through NF-κB and p53 inhibition. In contrast, PTEN-reduced PI3K/Akt activity, in P72 carrying cells, favors M1 phenotypes. LPS-stimulated R72 macrophages fail to reduce tumor growth in a mouse model of cancer, in contrast with P72 macrophages, which preserve M1 phenotype invivo and reduce tumor growth by enhancing antitumor T cell responses, consistent with antitumor functions of M1 macrophages. In addition, P72 macrophages contributed to increased mortality in a mouse model of LPS-induced endotoxemia. Therefore, given the high frequency of P72 in African Americans, cell signaling alterations driven by codon 72 of TP53 SNP may potentially contribute to differences in clinical outcomes and health disparities in common diseases associated with dysregulated macrophage activation.

Maternal exposure to nanopolystyrene induces neurotoxicity in offspring through P53-mediated ferritinophagy and ferroptosis in the rat hippocampus

There are increasing concerns regarding the rapid expansion of polystyrene nanoplastics (PS-NPs), which could impact human health. Previous studies have shown that nanoplastics can be transferred from mothers to offspring through the placenta and breast milk, resulting in cognitive deficits in offspring. However, the neurotoxic effects of maternal exposure on offspring and its mechanisms remain unclear. In this study, PS-NPs (50 nm) were gavaged to female rats throughout gestation and lactation to establish an offspring exposure model to study the neurotoxicity and behavioral changes caused by PS-NPs on offspring. Neonatal rat hippocampal neuronal cells were used to investigate the pathways through which NPs induce neurodevelopmental toxicity in offspring rats, using iron inhibitors, autophagy inhibitors, reactive oxygen species (ROS) scroungers, P53 inhibitors, and NCOA4 inhibitors. We found that low PS-NPs dosages can cause ferroptosis in the hippocampus of the offspring, resulting in a decline in the cognitive, learning, and memory abilities of the offspring. PS-NPs induced NOCA4-mediated ferritinophagy and promoted ferroptosis by inciting ROS production to activate P53-mediated ferritinophagy. Furthermore, the levels of the antioxidant factors glutathione peroxidase 4 (GPX4) and glutathione (GSH), responsible for ferroptosis, were reduced. In summary, this study revealed that consumption of PS-NPs during gestation and lactation can cause ferroptosis and damage the hippocampus of offspring. Our results can serve as a basis for further research into the neurodevelopmental effects of nanoplastics in offspring.Graphical

Overcoming Irinotecan Resistance by Targeting Its Downstream Signaling Pathways in Colon Cancer

Among the most popular chemotherapeutic agents, irinotecan, regarded as a prodrug belonging to the camptothecin family that inhibits topoisomerase I, is widely used to treat metastatic colorectal cancer (CRC). Although immunotherapy is promising for several cancer types, only microsatellite-instable (~7%) and not microsatellite-stable CRCs are responsive to it. Therefore, it is important to investigate the mechanism of irinotecan function to identify cellular proteins and/or pathways that could be targeted for combination therapy. Here, we have determined the effect of irinotecan treatment on the expression/activation of tumor suppressor genes (including p15Ink4b, p21Cip1, p27Kip1, and p53) and oncogenes (including OPN, IL8, PD-L1, NF-κB, ISG15, Cyclin D1, and c-Myc) using qRT-PCR, Western blotting, immunofluorescence (IF), and RNA sequencing of tumor specimens. We employed stable knockdown, neutralizing antibodies (Abs), and inhibitors of OPN, p53, and NF-κB to establish downstream signaling and sensitivity/resistance to the cytotoxic activities of irinotecan. Suppression of secretory OPN and NF-κB sensitized colon cancer cells to irinotecan. p53 inhibition or knockdown was not sufficient to block or potentiate SN38-regulated signaling, suggesting p53-independent effects. Irinotecan treatment inhibited tumor growth in syngeneic mice. Analyses of allograft tumors from irinotecan-treated mice validated the cell culture results. RNA-seq data suggested that irinotecan-mediated activation of NF-κB signaling modulated immune and inflammatory genes in mice, which may compromise drug efficacy and promote resistance. In sum, these results suggest that, for CRCs, targeting OPN, NF-κB, PD-L1, and/or ISG15 signaling may provide a potential strategy to overcome resistance to irinotecan-based chemotherapy.

Covalent Modification of p53 by (E)-1-(4-Methylpiperazin-1-yl)-3-(5-nitrofuran-2-yl)prop-2-en-1-one.

TP53 is commonly mutated in cancer, giving rise to loss of wild-type tumor suppressor function and increases in gain-of-function oncogenic roles. Thus, inhibition of mutant p53 and reactivation of wild-type function represents a potential means to target diverse tumor types. (E)-1-(4-Methylpiperazin-1-yl)-3-(5-nitrofuran-2-yl)prop-2-en-1-one (NSC59984), first identified from a high-throughput screen, induces wild-type p53 signaling and antiproliferative effects while inhibiting mutant p53 gain-of-function activities. Here, we investigate the specific mechanism of action of NSC59984 against p53. We found that NSC59984 reacts with thiols via an unusual Michael addition at the α-carbon. Covalent modification of p53 Cys124 and Cys229 was observed both following in vitro reaction and upon treatment of cells. Finally, we used a biotinylated form of NSC59984 and, separately, thermal proteome profiling to examine off-target effects, identifying several metabolic proteins involved in cellular metabolism as potential targets. These results demonstrate that covalent modification of p53 by NSC59984 leads to increased wild-type activity and suggest that potential reaction with metabolic enzymes may contribute to antiproliferative function.

A structure-based virtual screening identifies a novel MDM2 antagonist in the activation of the p53 signaling and inhibition of tumor growth.

p53, a tumor suppressor protein, has a vital role in the regulation of the cell cycle, apoptosis, and DNA damage repair. The degradation of p53 is predominantly controlled by the murine double minute 2 (MDM2) protein, a ubiquitin E3 ligase. The overexpression or amplification of MDM2 is commonly observed in various human cancers bearing wild-type p53 alleles, leading to the rapid degradation of the p53 protein and the attenuation of p53 tumor suppression functions. Thus, a major effort in p53-based cancer therapy has been to research MDM2 antagonists that specifically stabilize and activate p53, leading to the suppression of tumor growth. However, despite numerous efforts to develop MDM2 antagonists, to date they have failed to reach clinical use, largely because of the cytotoxicity associated with these small molecules. This study used our newly designed structure-based virtual screening approach on a commercial compound library to identify a novel compound, CGMA-Q18, which directly binds to MDM2, leading to the activation of p53, the induction of apoptosis, and cell cycle arrest in cancer cells. Notably, CGMA-Q18 significantly inhibited tumor xenograft growth in nude mice without observable toxicity. These findings highlight our useful virtual screening protocol and CGMA-Q18 as a putative MDM2 antagonist.

Pharmacological targeting of P300/CBP reveals EWS::FLI1-mediated senescence evasion in Ewing sarcoma

Ewing sarcoma (ES) poses a significant therapeutic challenge due to the difficulty in targeting its main oncodriver, EWS::FLI1. We show that pharmacological targeting of the EWS::FLI1 transcriptional complex via inhibition of P300/CBP drives a global transcriptional outcome similar to direct knockdown of EWS::FLI1, and furthermore yields prognostic risk factors for ES patient outcome. We find that EWS::FLI1 upregulates LMNB1 via repetitive GGAA motif recognition and acetylation codes in ES cells and EWS::FLI1-permissive mesenchymal stem cells, which when reversed by P300 inhibition leads to senescence of ES cells. P300-inhibited senescent ES cells can then be eliminated by senolytics targeting the PI3K signaling pathway. The vulnerability of ES cells to this combination therapy suggests an appealing synergistic strategy for future therapeutic exploration.

Inhibition of p53 Ameliorates Adenine-Induced Kidney Injury in Mice

Inhibition of p53 Ameliorates Adenine-Induced Kidney Injury in Mice

Exosomal let-7b-5p deriving from parietal epithelial cells attenuate renal fibrosis through suppression of TGFβR1 and ARID3a in obstructive kidney disease.

As renal progenitor cells, parietal epithelial cells (PECs) have demonstrated multilineage differentiation potential in response to kidney injury. However, the function of exosomes derived from PECs has not been extensively explored. Immunofluorescent staining of Claudin-1 was used to identify primary PECs isolated from mouse glomeruli. Transmission electron microscopy, nanoparticle tracking analysis, and western blotting were used to characterize the properties of PECs-derived exosomes (PEC-Exo). The therapeutic role of PEC-Exo in tubulointerstitial fibrosis was investigated in the unilateral ureteral obstruction (UUO) mouse model and TGF-β1-stimulated HK-2 cells. High-throughput miRNA sequencing was employed to profile PEC-Exo miRNAs. One of the most enriched miRNAs in PEC-Exo was knocked down by transfecting miRNA inhibitor, and then we investigated whether this candidate miRNA was involved in PEC-Exo-mediated tubular repair. The primary PECs expressed Claudin-1, PEC-Exo was homing to obstructed kidney, and TGF-β1 induced HK-2 cells. PEC-Exo significantly alleviated renal inflammation and ameliorated tubular fibrosis both invivo and invitro. Mechanistically, let-7b-5p, highly enriched in PEC-Exo, downregulated the protein levels of transforming growth factor beta receptor 1(TGFβR1) and AT-Rich Interaction Domain 3A(ARID3a) in tubular epithelial cells (TECs), leading to the inhibition of p21 and p27 to restoring cell cycle. Furthermore, administration of let-7b-5p agomir mitigated renal fibrosis invivo. Our findings demonstrated that PEC-derived exosomes significantly repressed the expression of TGFβR1 and ARID3a by delivering let-7b-5p, thereby alleviating renal fibrosis. This study provides novel insights into the role of PEC-Exo in the repair of kidney injury and new ideas for renal fibrosis intervention.

TRIM40 interacts with ROCK1 directly and inhibits colorectal cancer cell proliferation through the c-Myc/p21 axis

BackgroundColorectal cancer (CRC) is the most common malignancy of the digestive tract, and to date, morbidity and mortality rates remain high. While existing therapeutic methods have achieved certain effective outcomes, there are still many problems in treating this disease. Therefore, it is still urgent to constantly find new therapeutic targets in CRC that could lead to new therapeutics. MethodsImmunohistochemistry, Real-time PCR and Western Blot were employed to measure mRNA and protein levels of the target protein, respectively. The proliferation ability of CRC cells was evaluated using ATP assay, Soft agar assay, and nude mouse subcutaneous tumorigenesis assay. Protein Degradation Assay was conducted to determine protein degradation rate, while Ubiquitination assay was used to assess the ubiquitination modification level of target proteins. Immunoprecipitation assay was used to study protein interactions, and pull-down assay was employed to investigate direct interactions between proteins. ResultsTRIM40 was significantly down-regulated in CRC tissues, with its expression levels positively correlating with disease prognosis. Using both in vitro and in vivo approaches, it was demonstrated that TRIM40 could significantly inhibit the proliferation of CRC cells. Molecular mechanism studies showed that TRIM40 directly binds to and ubiquitinates ROCK1 protein, accelerating its degradation and subsequently reducing the stability of c-Myc protein. This cascade of events results in the release of transcriptional inhibition of p21 by c-Myc, leading to increased p21 expression and G0/G1 phase arrest in CRC cells. ConclusionThis research suggests that TRIM40 could be a valuable therapeutic target for the treatment of CRC.

CBR-470-1 protects against cardiomyocyte death in ischaemia/reperfusion injury by activating the Nrf2–GPX4 cascade

Cardiac ischaemia/reperfusion (I/R) impairs mitochondrial function, resulting in excessive oxidative stress and cardiomyocyte ferroptosis and death. Nuclear factor E2-related factor 2 (Nrf2) is a key regulator of redox homeostasis and has cardioprotective effects against various stresses. Here, we tested whether CBR-470-1, a noncovalent Nrf2 activator, can protect against cardiomyocyte death caused by I/R stress. Compared with vehicle treatment, the administration of CBR-470-1 (2 mg/kg) to mice significantly increased Nrf2 protein levels and ameliorated the infarct size, the I/R-induced decrease in cardiac contractile performance, and the I/R-induced increases in cell apoptosis, ROS levels, and inflammation. Consistently, the beneficial effects of CBR-470-1 on cardiomyocytes were verified in a hypoxia/reoxygenation (H/R) model in vitro, but this cardioprotection was dramatically attenuated by the GPX4 inhibitor RSL3. Mechanistically, CBR-470-1 upregulated Nrf2 expression, which increased the expression levels of antioxidant enzymes (NQO1, SOD1, Prdx1, and Gclc) and antiferroptotic proteins (SLC7A11 and GPX4) and downregulated the protein expression of p53 and Nlrp3, leading to the inhibition of ROS production and inflammation and subsequent cardiomyocyte death (apoptosis, ferroptosis and pyroptosis). In summary, CBR-470-1 prevented I/R-mediated cardiac injury possibly through inhibiting cardiomyocyte apoptosis, ferroptosis and pyroptosis via Nrf2-mediated inhibition of p53 and Nlrp3 and activation of the SLC7A11/GPX4 pathway. Our data also highlight that CBR-470-1 may serve as a valuable agent for treating ischaemic heart disease.

Hepatitis B Virus X Protein Induces Reactive Oxygen Species Generation via Activation of p53 in Human Hepatoma Cells.

Hepatitis B virus (HBV), particularly through the HBx protein, induces oxidative stress during liver infections. This study reveals that HBx increases reactive oxygen species (ROS) via two distinct mechanisms. The first mechanism is p53-independent, likely involving mitochondrial dysfunction, as demonstrated by elevated ROS levels in p53-deficient Hep3B cells and p53-knocked-down HepG2 cells after HBx expression or HBV infection. The increase in ROS persisted even when p53 transcriptional activity was inhibited by pifithrin-α (PFT-α), a p53 inhibitor. The second mechanism is p53-dependent, wherein HBx activates p53, which then amplifies ROS production through a feedback loop involving ROS and p53. The ability of HBx to elevate ROS levels was higher in HepG2 than in Hep3B cells. Knocking down p53 in HepG2 cells lowered ROS levels, while ectopic p53 expression in Hep3B cells raised ROS. HBx-activated p53 downregulated catalase and upregulated manganese-dependent superoxide dismutase, contributing to ROS amplification. The transcriptional activity of p53 was crucial for these effects, as cells with a p53 R175H mutation or those treated with PFT-α generated less ROS. Additionally, HBx variants with Ser-101 increased p53 and ROS levels, whereas variants with Pro-101 did not. These dual mechanisms of HBx-induced ROS generation are likely significant in the pathogenesis of HBV and may contribute to liver diseases, including hepatocellular carcinoma.

Targeting MDM2-mediated suppression of p53 with idasanutlin: a promising therapeutic approach for acute lymphoblastic leukemia.

Despite available treatments for acute lymphoblastic leukemia (ALL), the disease's high clinical variability necessitates new therapeutic strategies, particularly for patients with high-risk features. The tumor suppressor protein p53, encoded by the TP53 gene and known as the guardian of the genome, plays a crucial role in preventing tumor development. Over 90% of ALL cases initially harbor wild-type TP53. Reactivation of p53, which is encoded from the wild type TP53 but lost its function for several reasons, is an attractive therapeutic approach in cancer treatment. p53 can be activated in a non-genotoxic manner by targeting its primary repressor, the MDM2 protein. Clinical trials involving MDM2 inhibitors are currently being conducted in a growing body of investigation, reflecting of the interest in incorporating these treatments into cancer treatment strategies. Early-phase clinical trials have demonstrated the promise of idasanutlin (RG7388), one of the developed compounds. It is a second-generation MDM2-p53 binding antagonist with enhanced potency, selectivity, and bioavailability. The aim of this study is to evaluate the efficacy of RG7388 as a therapeutic strategy for ALL and to investigate its potential impact on improving treatment outcomes for high-risk patients. RG7388 potently decreased the viability in five out of six ALL cell lines with diverse TP53 mutation profiles, whereas only one cell line exhibited high resistance. RG7388 induced a pro-apoptotic gene expression signature with upregulation of p53-target genes involved in the intrinsic and extrinsic pathways of apoptosis. Consequently, RG7388 led to a concentration-dependent increase in caspase-3/7 activity and cleaved poly (ADP-ribose) polymerase. In this research, RG7388 was investigated with pre-clinical methods in ALL cells as a novel treatment strategy. This study suggests further functional research and in-vivo evaluation, and it highlights the prospect of treating p53-functional ALL with MDM2 inhibitors.