Search Results (584)

Background/Objectives: The 2019 WHO classification redefined high-grade gastrointestinal neuroendocrine neoplasms (GI NENs), encompassing not only poorly differentiated neuroendocrine carcinomas (NECs), but also well-differentiated grade 3 neuroendocrine tumors (NETs G3). Since both subtypes share a Ki-67 index > 20%, distinguishing them based solely on morphology is challenging. Prior studies have shown TP53 alterations in NECs but not in NETs. This study aimed to evaluate clinico-morphological parameters and the immunohistochemical (IHC) expression of p53 in high-grade GI NENs to identify relevant correlations. Methods: Tumors were stratified by Ki-67 index into two groups: >20–50% and >50%. p53 IHC expression was assessed as “wild-type” (1–20% positive tumor cells) or “non-wild-type” (absence or >20% positivity). Correlations were analyzed between Ki-67, p53 status, and various pathological features. Results: Significant correlations were found between the Ki-67 index and maximum tumor size, pT stage, lymphovascular invasion, perineural infiltration, and diagnostic classification. Similarly, p53 immunohistochemical status was significantly associated with lymphovascular invasion, lymph node metastasis, and tumor classification (NET G3 versus NEC, including NEC components of MiNENs). Conclusions: The findings support the value of Ki-67 and p53 as complementary biomarkers in the pathological evaluation of high-grade GI NENs. Their significant associations with key morphological parameters support their utility in differentiating NETs G3 from NECs, particularly in cases showing overlapping histological features. The immunohistochemical profile of p53 may serve as a useful diagnostic adjunct in routine practice. Full article

The protein p53, often referred to as the “guardian of the genome,” is essential for preserving cellular balance and preventing cancerous transformations. As one of the most commonly altered genes in human cancers, its impaired function is associated with tumor initiation, development, and resistance to treatment. Exploring the diverse roles of p53, which include regulating the cell cycle, repairing DNA, inducing apoptosis, reprogramming metabolism, and modulating immunity, provides valuable insights into cancer mechanisms and potential treatments. This review integrates recent findings on p53′s dual nature, functioning as both a tumor suppressor and an oncogenic promoter, depending on the context. Wild-type p53 suppresses tumors by inducing cell cycle arrest or apoptosis in response to genotoxic stress, while mutated variants often lose these functions or gain novel pro-oncogenic activities. Emerging evidence highlights p53′s involvement in non-canonical pathways, such as regulating tumor microenvironment interactions, metabolic flexibility, and immune evasion mechanisms. For instance, p53 modulates immune checkpoint expression and influences the efficacy of immunotherapies, including PD-1/PD-L1 blockade. Furthermore, advancements in precision diagnostics, such as liquid biopsy-based detection of p53 mutations and AI-driven bioinformatics tools, enable early cancer identification and stratification of patients likely to benefit from targeted therapies. Therapeutic strategies targeting p53 pathways are rapidly evolving. Small molecules restoring wild-type p53 activity or disrupting mutant p53 interactions, such as APR-246 and MDM2 inhibitors, show promise in clinical trials. Combination approaches integrating gene editing with synthetic lethal strategies aim to exploit p53-dependent vulnerabilities. Additionally, leveraging p53′s immunomodulatory effects through vaccine development or adjuvants may enhance immunotherapy responses. In conclusion, deciphering p53′s complex biology underscores its unparalleled potential as a biomarker and therapeutic target. Integrating multi-omics analyses, functional genomic screens, and real-world clinical data will accelerate the translation of p53-focused research into precision oncology breakthroughs, ultimately improving patient outcomes. Full article

Background: Lysosomal-associated membrane protein 1 (LAMP1), typically localized to the lysosomal membrane, is increasingly implicated as a marker of cancer aggressiveness and metastasis when expressed on the cell surface. This study aimed to develop a LAMP1-targeted antibody-based PET tracer and assess its efficacy in mouse models of human breast and colon adenocarcinoma. Methods: To determine the source of LAMP1 expression, we utilized human single-cell RNA sequencing and spatial transcriptomics, complemented by in-house flow cytometry on xenografted mouse models. Tissue microarrays of multiple epithelial cancers and normal tissue were stained for LAMP-1, and staining was quantified. An anti-LAMP1 monoclonal antibody was conjugated with desferrioxamine (DFO) and labeled with zirconium-89 (⁸⁹Zr). Human triple-negative breast cancer (MDA-MB-231) and colon cancer (Caco-2) cell lines were implanted in nude mice. PET/CT imaging was conducted at 24, 72, and 168 h post-intravenous injection of ⁸⁹Zr-DFO-anti-LAMP1 and ⁸⁹Zr-DFO-IgG (negative control), followed by organ-specific biodistribution analyses at the final imaging time point. Results: Integrated single-cell and spatial RNA sequencing demonstrated that LAMP1 expression was localized to myeloid-derived suppressor cells (MDSCs) and cancer-associated fibroblasts (CAFs) in addition to the cancer cells. Tissue microarray showed significantly higher staining for LAMP-1 in tumor tissue compared to normal tissue (3986 ± 2635 vs. 1299 ± 1291, p < 0.001). Additionally, xenograft models showed a significantly higher contribution of cancer cells than the immune cells to cell surface LAMP1 expression. In vivo, PET imaging with ⁸⁹Zr-DFO-anti-LAMP1 PET/CT revealed detectable tumor uptake as early as 24 h post-injection. The ⁸⁹Zr-DFO-anti-LAMP1 tracer demonstrated significantly higher uptake than the control ⁸⁹Zr-DFO-IgG in both models across all time points (MDA-MB-231 SUV_max at 168 h: 12.9 ± 5.7 vs. 4.4 ± 2.4, p = 0.003; Caco-2 SUV_max at 168 h: 8.53 ± 3.03 vs. 3.38 ± 1.25, p < 0.01). Conclusions: Imaging of cell surface LAMP-1 in breast and colon adenocarcinoma is feasible by immuno-PET. LAMP-1 imaging can be expanded to adenocarcinomas of other origins, such as prostate and pancreas. Full article

Network theory analysis has emerged as a powerful approach for investigating the complex behavior of dynamic and interactive systems, including proteomic systems. One key application of these methods is the study of long-range signaling dynamics in proteins, a phenomenon known as allostery. In this study, we applied computational models using network theory analysis to explore long-range electrostatic interactions and allosteric drug rescue mechanisms in the DNA-binding domain (DBD) of the p53 protein, a critical tumor suppressor whose dysfunction, often caused by missense mutations, is implicated in over 50% of human cancers. Using heat kernel and Wasserstein distance-based analyses, we explored the allosteric behavior of p53-DBD constructs with the Y220C mutation in the presence or absence of allosteric effector drugs. Our results demonstrated that these network theory-based protocols effectively detected the differential efficacies of small molecule allosteric effector drug compounds in restoring long-range electrostatic dynamics in the Y220C mutant. Furthermore, our approach identified key long-range electrostatic interactions critical to both the nominal and drug-rescued functionality of the p53-DBD, providing valuable insights into allosteric modulation and its therapeutic potential. Full article

Cancer remains one of the most formidable challenges to human health; hence, developing effective treatments is critical for saving lives. An important strategy involves reactivating tumor suppressor genes, particularly p53, by targeting their negative regulator MDM2, which is essential in promoting cell cycle arrest and apoptosis. Leveraging a drug repurposing approach, we screened over 24,000 clinically tested molecules to identify new MDM2 inhibitors. A key innovation of this work is the development and application of a selective cleaning algorithm that systematically filters assay data to mitigate noise and inconsistencies inherent in large-scale bioactivity datasets. This approach significantly improved the predictive accuracy of our machine learning model for pIC₅₀ values, reducing RMSE by 21.6% and achieving state-of-the-art performance (R² = 0.87)—a substantial improvement over standard data preprocessing pipelines. The optimized model was integrated with structure-based virtual screening via molecular docking to prioritize repurposing candidate compounds. We identified two clinical CB1 antagonists, MePPEP and otenabant, and the statin drug atorvastatin as promising repurposing candidates based on their high predicted potency and binding affinity toward MDM2. Interactions with the related proteins MDM4 and BCL2 suggest these compounds may enhance p53 restoration through multi-target mechanisms. Quantum mechanical (ONIOM) optimizations and molecular dynamics simulations confirmed the stability and favorable interaction profiles of the selected protein–ligand complexes, resembling that of navtemadlin, a known MDM2 inhibitor. This multiscale, accuracy-boosted workflow introduces a novel data-curation strategy that substantially enhances AI model performance and enables efficient drug repurposing against challenging cancer targets. Full article

Introduction: The interface between T cells and the tumor microenvironment, termed the ‘immunological synapse’, consists of multiple checkpoint protein pairs co-expressed on both sides of the synapse. mir-16, a microRNA from a widely known tumor-suppressor family of miRNAs, was previously shown by us to be downregulated in melanoma. As other miRNAs from this family have been shown to directly target checkpoint proteins, here we investigated whether miR-16 influences the expression patterns of checkpoint proteins in melanoma. Methods: Single-cell gene expression data from the melanoma microenvironment were retrieved from a public database. Melanoma cell lines were established from metastatic lesions and transiently transfected with an hsa-miR-16-5p-mimic RNA or a mir-16-expressing plasmid. The mRNA expression profiles were analyzed using an Affymetrix microarray. Direct targets of miR-16 were identified by luciferase reporter assays. Protein levels were assessed by Western blotting. Results: Bioinformatic analysis revealed that the expression levels of eight checkpoint mRNAs, known to be present on the melanoma side of the immunological synapse, were highly correlated. Four of these mRNAs contained putative binding sites for the miR-15/16 family. miR-16 expression was significantly reduced in melanoma cells, compared to normal melanocytes. Luciferase reporter assays demonstrated that miR-16 directly targets the 3′ untranslated regions (3′UTRs) of CD40, CD80. The mRNAs downregulated following miR-16 overexpression were highly enriched for genes involved in autophagy, vesicle-mediated transport, and the regulation of protein membrane localization. Among these, VTI1B and SMPD1 were confirmed to be direct targets of miR-16. Transient overexpression of miR-16 resulted in a significant reduction in SMPD1 and VTI1B levels in melanoma cell lines. Conclusions: Our findings suggest that miR-16 potentially modulates melanoma tumorigenesis, metastasis and immunogenicity by altering the composition of checkpoint proteins at the immunological synapse and by regulating cellular pathways associated with intracellular trafficking and transmembrane protein presentation. Full article

Colon cancer is one of the leading malignant tumors worldwide, and the membrane protein PAQR3 has been identified as a tumor suppressor in multiple cancers. Notably, the peptide synthesized from 6 to 55 amino acids at the N-terminal of PAQR3 (P6-55) has been shown to effectively inhibit the growth of gastric cancer cells. This study aims to elucidate the mechanism of PAQR3 and explore its therapeutic potential in colon cancer. CCK8 cell viability assays, colony formation assays, and transwell migration assays were employed to systematically assess the inhibitory effects of PAQR3 on the proliferation and migration of colon cancer cells. Furthermore, we confirmed that P6-55 exhibits functional similarities to PAQR3, effectively inhibiting the growth of colon cancer in vitro and in vivo. RNA sequencing revealed that PAQR3 suppresses tumor growth via the PI3K-AKT signaling pathway, providing a strong theoretical foundation for therapeutic strategies targeting PAQR3/P6-55. In conclusion, our findings highlight the therapeutic potential of PAQR3/P6-55 as novel colon cancer inhibitors. Full article

The tumor suppressor p16^INK4a, encoded by CDKN2A, is frequently inactivated in cancer through genetic or epigenetic mechanisms. While promoter hypermethylation is the most common epigenetic cause, aberrant methylation of CDKN2A exon 2 has also been associated with various tumor types. However, analyzing DNA methylation of exon 2 is challenging due to its high sequence similarity with CDKN2B. We developed a pyrosequencing assay to analyze CpGs in CDKN2A exon 2, which was previously found to be hypermethylated in breast cancer. Our novel primer set enabled co-amplification of the homologous regions in CDKN2A, including CpGs 1–24, and CDKN2B CpGs 1–23. By quantifying the proportion of CDKN2A, we could accurately determine methylation levels for CpGs in CDKN2A exon 2. This method was applied to patient-derived glioma cells and commercial breast cancer cell lines. To reveal the role of exon 2 methylation in gene regulation, we additionally examined CDKN2A^INK4a promoter methylation and expression at both mRNA and protein levels in breast cancer cell lines. We observed a range of (epi)genetic alterations, including homozygous deletions, transcript-specific expression, and exon 2 skipping. Our findings indicate that both promoter and exon 2 methylation contribute to regulation of CDKN2A expression. This novel method provides a valuable tool for future studies seeking a deeper understanding of CDKN2A regulation in cancer. Full article

Hepatocellular carcinoma (HCC) imposes a significant burden on global public health. Exposure to aflatoxins, potent mycotoxins produced by Aspergillus fungi contaminating staple foods, and chronic hepatitis B virus (HBV) infection are major etiological factors, especially where they co-exist. This review examines the critical role of the p53 tumor suppressor pathway as a primary target and convergence point for the carcinogenic actions of aflatoxins and HBV. Aflatoxin B₁ (AFB₁), a Group 1 carcinogen, exerts significant genotoxicity, characteristically inducing a specific hotspot mutation (R249S) in the TP53 gene via DNA adduct formation, thereby compromising p53’s critical tumor suppressor functions. This R249S mutation is considered a molecular fingerprint of aflatoxin exposure. Concurrently, the HBV X protein (HBx) functionally inactivates wild-type p53 through direct binding and by promoting its degradation. The synergistic disruption of the p53 pathway, driven by AFB₁-induced mutation and amplified by HBV-mediated functional inhibition, significantly enhances the risk of HCC development. This review addresses how aflatoxin exposure alters key aspects of p53 and how this damage interacts with HBV-mediated p53 suppression, providing crucial insights into hepatocarcinogenesis. The knowledge synthesized here underscores the importance of mitigating aflatoxin exposure alongside HBV control for effective HCC prevention and treatment strategies. Full article

Thyroid carcinogenesis has multiple hallmarks, including evasion of tumor suppressors. Reactivation of wild-type p53 function is the ultimate goal in cancer therapy, which requires an understanding of the p53 suppression mechanism specific to the cancer type. MiR-7-5p and IPO7 are implicated in the pathogenesis of several human diseases. This work aims to investigate the role of miR-7-5p and IPO7 in p53 regulation in papillary thyroid cancer (PTC) cells. Primary cultured thyroid cells and FFPE thyroid tissues from PTC and benign cases were used. Functional experiments were performed by transfection with IPO7 siRNA or miR-7-5p mimic/inhibitor, followed by apoptosis and luciferase reporter assays, immunoblot assays, and RT-PCR. The expression and subcellular localization of IPO7, p53, MDM2, and ribosomal proteins (RPL11 and RPL5) were studied by immunofluorescence staining and confocal microscopy. The results show that IPO7 is overexpressed in PTC and regulated by miR-7-5p. Modulation of IPO7 expression in cultured thyroid cells altered the nucleocytoplasmic shuttling of p53, MDM2, RPL11, and RPL5, in addition to the p53 protein level and activity. The expression pattern of IPO7, p53, and MDM2 in cultured thyroid cells and clinical thyroid tissue specimens confirmed the association between IPO7 overexpression and reduced p53 stability in PTC. In conclusion, the data here show that p53 level and activity are differentially controlled in malignant and benign thyroid cells through miR-7-5P/IPO7-mediated regulation of RP-MDM2-p53 nucleocytoplasmic trafficking. In PTC, downregulation of miR-7-5p with consequent overexpression of IPO7 might be a protective mechanism used by cancer cells to evade p53 growth suppression during carcinogenesis. Full article

In Chronic Lymphocytic Leukemia (CLL), mutations at the TP53 tumor suppressor gene are an important hallmark since they may strongly influence the therapeutic decision. PRIMA-1^Met (also known as APR-246/Eprenetapopt) is a small molecule able to restore the wild-type (wt) p53 conformation to mutant p53 proteins and to stimulate apoptosis in tumor cells; in addition, it can deplete the glutathione reservoir, increasing reactive oxygen species (ROS) production. In this study, we investigated whether combining PRIMA-1^Met with Sulfasalazine (SAS), a SLC7A11/xCT inhibitor, reduces CLL cell viability by targeting mutant p53 and the glutathione pathway. The results demonstrated that, in CLL cells, PRIMA-1^Met did not restore the wt functions in the mutant p53 proteins, but it strongly reduced the antioxidant defense and induced cell death. PRIMA-1^Met and SAS combination synergistically reduced cell survival regardless of p53 status and further impaired antioxidant capacity, especially in mutant p53 cells, linking their cytotoxic effect to redox imbalance. Thus, the association of PRIMA-1^Met with drugs targeting the antioxidant response could represent a valid strategy to kill CLL cells carrying either wt or mutant p53. Full article

Approximately 15% of cancers worldwide are caused by oncogenic viruses. These infectious agents utilize multiple strategies to dysregulate their host cells as a means of viral reproduction. While this typically involves a small number of viral oncoproteins known to interact with a myriad of host cell proteins, direct binding with the tumor suppressor retinoblastoma protein (pRb) as a means to dysregulate the cell cycle appears to be a common mechanism among most known oncogenic viruses. This review evaluates the shared structural themes of binding motif, intrinsic disorder, and viral oncoprotein phosphorylation, utilized by eight different oncogenic viruses for the subjugation of pRb. Cancer caused by oncogenic viruses represents one of the few potentially preventable forms of cancer. The more we understand the common strategies used by these infectious agents, the better equipped we will be to further optimize vaccination and therapeutic strategies to fight them. Full article

Background/Objectives: Death-associated protein kinase 1 (DAPK1) is a serine/threonine kinase that plays a crucial role in cancer by regulating apoptosis through interactions with TP53. Aberrant expression of DAPK1 was shown in certain types of human cancer contributing to tumor progression and chemoresistance. This study aimed to investigate the role of DAPK1 in high-grade serous ovarian cancer (HGSOC) and to evaluate the therapeutic potential of restoring its kinase activity, including the use of truncated DAPK1 variants, to overcome chemoresistance and enhance tumor suppression. Methods: Gene expression analysis was performed on ovarian cancer tissues compared to benign controls to assess DAPK1 downregulation and its epigenetic regulation. Prognostic relevance was evaluated in a cohort of 1436 HGSOC patient samples. Functional restoration of DAPK1 was conducted in HGSOC cell lines and patient-derived primary tumor cells using vector-based expression or in vitro-transcribed (IVT) DAPK1 mRNA, including the application of truncated DAPK1 (ΔDAPK1) forms. To assess apoptosis, Caspase activation assays, 2D-colony formation assays, and cell survival assays were performed. To analyze the reactivation of DAPK1 downstream signaling, phosphorylation of p53 at Ser20 and the expression of p53 target proteins were examined. Chemosensitivity to Paclitaxel and Cisplatin was quantified by changes in IC₅₀ values. Results: DAPK1 expression was significantly downregulated in ovarian cancer compared to benign tissue, correlating with epigenetic silencing, and showed prognostic value in early-stage HGSOC. Restoration of DAPK1 activity, including ΔDAPK1 variants, led to phosphorylation of p53 Ser20, increased expression of p53 target proteins, and Caspase-dependent apoptosis. Reactivation of DAPK1 sensitized both established HGSOC cell lines and patient-derived ascites cells to Paclitaxel and Cisplatin. These effects occurred through both p53-dependent and p53-independent pathways, enabling robust tumor suppression even in p53-mutant contexts. Conclusions: Reactivation of DAPK1, particularly through truncated variants, represents a promising therapeutic strategy to overcome chemoresistance in HGSOC. The dual mechanisms of tumor suppression provide a strong rationale for developing DAPK1-based therapies to enhance the efficacy of standard chemotherapy, especially in patients with chemoresistant or p53-deficient tumors. Future work should focus on optimizing delivery approaches for DAPK1 variants and assessing their synergistic potential with emerging targeted treatments in clinical settings. Full article

Objectives: To assess amide proton transfer weighted (APTw) MR imaging capabilities in differentiating high-grade glial tumors across alpha-thalassemia/mental retardation X-linked (ATRX) expression, tumor-suppressor protein p53 expression (p53), O6-methylguanine-DNA methyltransferase promoter (MGMTp) methylation, isocitrate dehydrogenase (IDH) status, and proliferation marker Ki-67 (Ki-67 index) as a preoperative diagnostic aid. Material & Methods: A total of 42 high-grade glioma WHO grade 4 (HGG) patients were evaluated prospectively (30 males and 12 females). All patients were examined using conventional MRI, including the following: T1w-MPRAGE pre- and post-contrast administration, conventional T2w and 3D FLAIR, and APTw imaging with a 3T MR scanner. Receiver operating characteristic (ROC) curves were calculated for the APTw% mean, median, and max signal for the different molecular biomarkers. A logistic regression model was constructed for combined mean and median APTw% signals for p53 expression. Results: The whole-tumor max APTw% signal could significantly differentiate MGMTp from non-MGMTp HGG, p = 0.035. A cutoff of 4.28% max APTw% signal yielded AUC (area under the curve) = 0.702, with 70.6% sensitivity and 66.7% specificity. The mean/median APTw% signals differed significantly in p53 normal versus p53-overexpressed HGG s: 1.81%/1.83% vs. 1.15%/1.18%, p = 0.002/0.006, respectively. Cutoffs of 1.25%/1.33% for the mean/median APTw% signals yielded AUCs of 0.786/0.757, sensitivities of 76.9%/76.9%, and specificities of 50%/66.2%, p = 0.002/0.006, respectively. A logistic regression model with a combined mean and median APTw% signal for p53 status yielded an AUC = 0.788 and 76.9% sensitivity and 66.2% specificity. ATRX-, IDH- wild type (wt) vs. mutation (mut), and the level of Ki-67 did not differ significantly, but trends were found: IDH-wt and low Ki-67 showed higher mean/median/max APTw% signals vs. IDH-mut and high Ki-67, respectively. ATRX-wt vs. mutation showed higher mean and median APTw% signals but lower max APTw% signal. Conclusions: APTw imaging can potentially be a useful marker for the stratification of p53 expression and MGMT status in high-grade glioma in the preoperative setting and potentially aid surgical decision-making. Full article

Background/Objectives: Ribosomal Protein Lateral Stalk Subunit P2 (RPLP2), an important ribosomal protein, is mainly involved in modulating protein synthesis and plays an essential role in the carcinogenesis of many cancers. However, its precise impact on diffuse large B-cell lymphoma (DLBCL) remains unknown. Methods: This study utilized siRNA to knock down RPLP2, aiming to investigate its role in DLBCL progression. RT-qPCR and immunohistochemistry (IHC) were employed to assess RPLP2 and frataxin (FXN) expression levels in DLBCL. CCK8 and colony formation assays measured cell proliferation inhibition upon RPLP2 deletion, while transwell migration assays analyzed reduced cell motility. Lipid ROS and iron assays quantified ferroptosis markers to elucidate RPLP2’s regulation of FXN-mediated ferroptosis. Xenograft mouse models validated tumor suppression effects in vivo. Results: Here, we reveal that elevated RPLP2 expression is significantly correlated to unfavorable prognosis in DLBCL patients. In addition, we demonstrate that RPLP2 deletion dramatically reduces the cell proliferation and migration of DLBCL. Besides, knockdown of RPLP2 triggers ferroptosis via regulating ferroptosis suppressor FXN activity. Moreover, we discover that Destruxin b could target RPLP2 to suppress the development of DLBCL. Lastly, the combination of Destruxin b with Dox remarkably improves the anti-tumor effect. Conclusions: In general, the present study reveals the oncogenic role of RPLP2 in DLBCL, uncovers an unrecognized regulatory axis of ferroptosis, and identifies a specific inhibitor targeting RPLP2 to restrain DLBCL progression, suggesting that RPLP2 could be a potential target for DLBCL treatment. Full article