Impaired Cell Cycle Research Articles

Exploiting metabolic vulnerability in glioblastoma using a brain-penetrant drug with a safe profile.

Glioblastoma is one of the most treatment-resistant and lethal cancers, with a subset of self-renewing brain tumour stem cells (BTSCs), driving therapy resistance and relapse. Here, we report that mubritinib effectively impairs BTSC stemness and growth. Mechanistically, bioenergetic assays and rescue experiments showed that mubritinib targets complex I of the electron transport chain, thereby impairing BTSC self-renewal and proliferation. Gene expression profiling and Western blot analysis revealed that mubritinib disrupts the AMPK/p27Kip1 pathway, leading to cell-cycle impairment. By employing in vivo pharmacokinetic assays, we established that mubritinib crosses the blood-brain barrier. Using preclinical patient-derived and syngeneic models, we demonstrated that mubritinib delays glioblastoma progression and extends animal survival. Moreover, combining mubritinib with radiotherapy or chemotherapy offers survival advantage to animals. Notably, we showed that mubritinib alleviates hypoxia, thereby enhancing ROS generation, DNA damage, and apoptosis in tumours when combined with radiotherapy. Encouragingly, toxicological and behavioural studies revealed that mubritinib is well tolerated and spares normal cells. Our findings underscore the promising therapeutic potential of mubritinib, warranting its further exploration in clinic for glioblastoma therapy.

Abstract P011: STN1 (OBFC1) promotes DNA double-strand break repair in a potentially CTC1-STN1-TEN1 (CST) complex-independent role in pancreatic cancer

Abstract Purpose: Pancreatic cancer (PC) is an aggressive lethal tumor with an unmet need for novel therapeutic approaches. KRAS activating mutations occur in 90-95% of PC and contribute to tumor progression and resistance to therapy, including radiation. The mechanisms by which oncogenic KRAS promotes radiation resistance are critical to understand in order to identify novel therapies. Methods: We first analyzed the expression levels of DNA damage response and repair genes using Affymetrix RNA expression microarray in isogenic HCT116 and SW48 cells with KRAS wide-type and KRASG13D activating mutations to identify novel targets by which KRAS mutations may confer radiation resistance. We analyzed the expression of STN1 in pancreas normal and cancer tissues and assessed the correlation with PC clinical outcomes using TCGA dataset. Human tumor xenografts were generated to explore the role of STN1 on tumor growth in vivo. Radiation response was assessed through clonogenicity and gH2AX foci assays. Homologous recombination (HR) and non-homologous end joining (NHEJ) repair reporter assays, chromatin spreading assay, cell cycle analysis, mitotic catastrophe, Annexin-V assays were performed to investigate the mechanisms of radiation-induced cell death. Mass spectrometry analysis was performed to identify STN1 interacting proteins important in DNA damage response and further validated by immunoprecipitation and immunoblotting. Results: We find that KRAS activation increases STN1 expression to enhance DNA double strand break repair capacity in PC. STN1 is a component of the CST complex normally important for telomere duplication and maintenance. We find that STN1 is significantly upregulated in PC, especially in aggressive subtypes of PC, associates with KRAS oncogenic mutations, and correlates with poor patient clinical outcomes. Genetic silencing or pharmacologic inhibition of KRAS signaling decreases STN1 expression in PC cells, suggesting KRAS signaling positively regulates STN1 expression. Interestingly, STN1 depletion reduces tumor growth in a heterotopic model of KRAS mutant PC. Mechanistically, depletion of STN1 potentiates DNA damage, replication stress, and sensitizes PC cells to ionizing radiation independent of CTC1 and TEN1. In support of this finding, STN1 silencing reduces both HR and NHEJ repair of DSBs. Furthermore, knockdown of STN1 impairs cell cycle arrest at the G2/M phase in response to ionizing radiation, which is accompanied with increased mitotic catastrophe, radiation-induced apoptosis. Proteomic analysis reveals that STN1 physically interacts with many proteins important for DNA repair, replication and cell cycle progression, including ATM, DICER1, CEP164, and CEP250. Conclusion: Our findings have revealed a novel, potentially CST complex-independent role of STN1 in DSB repair after radiation. STN1 may function at one of the apical nodes in the DNA damage response pathway by interacting with ATM. Our findings suggest STN1 may be a promising target for improving genotoxic therapies in KRAS mutant cancers, including PC. Citation Format: Tiantian Cui, Changxian Shen, Linlin Yang, Ling Gui, Sergio Corrales-Guerrero, Sindhu Nair, Joanna M. Karasinska, James T. Topham, Xiaoli Ping, Jeremy M. Stark, Terence M. Williams.STN1 (OBFC1) promotes DNA double-strand break repair in a potentially CTC1-STN1-TEN1 (CST) complex-independent role in pancreatic cancer.[abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Translating Targeted Therapies in Combination with Radiotherapy; 2025 Jan 26-29; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2025;31(2_Suppl):Abstract nr P011

Molecular evidence for the efficacy of PBM therapy in the treatment of oral lichen planus.

Oral lichen planus (OLP) is a chronic inflammatory disease, in which T-Lymphocytes induce apoptosis of basal keratinocytes, leading to the formation of symptomatic lesions. It is assumed that blocking the cell death program and enhancing cell proliferation would be crucial to the healing process. The aim of the study was to verify the efficacy of Photobiomodulation (PBM) in OLP management, by evaluating the effects of laser irradiation on the processes of apoptosis and cell proliferation. Twenty patients with OLP underwent PBM with 810 nm diode laser (0.5 W, 30 s, 1.2 J/cm2), 3 times a week for one month. The size and clinical scores of the lesions and pain level were recorded and compared before and after therapy using Thongprasom sign scoring system and Visual Analogue Scale, respectively. Biopsies were taken before and after therapy and analyzed immunohistochemically for bcl-2 and Ki-67 expression. Tissue sections from 10 healthy volunteers were used as controls for the levels of these markers in normal oral mucosa. PBM significantly reduced patients' pain intesity and improved the clinical signs of the lesions. OLP tissue sections demonstrated lower staining for bcl-2 and Ki-67 compared to healthy controls. After therapy the expression of bcl-2 increased significantly. An enhance in Ki-67 immunoreactivity was revealed predominantly in the atrophic-erosive epithelium. PBM is an effective treatment modality for OLP patients. Erosive forms of the disease responded better to laser irradiation than keratotic subtypes. At the molecular level, PBM is likely to recover the impaired cell cycle mechanisms and keratinocyte proliferation.

Cbf11 and Mga2 function together to activate transcription of lipid metabolism genes and promote mitotic fidelity in fission yeast.

Within a eukaryotic cell, both lipid homeostasis and faithful cell cycle progression are meticulously orchestrated. The fission yeast Schizosaccharomyces pombe provides a powerful platform to study the intricate regulatory mechanisms governing these fundamental processes. In S. pombe, the Cbf11 and Mga2 proteins are transcriptional activators of non-sterol lipid metabolism genes, with Cbf11 also known as a cell cycle regulator. Despite sharing a common set of target genes, little was known about their functional relationship. This study reveals that Cbf11 and Mga2 function together in the same regulatory pathway, critical for both lipid metabolism and mitotic fidelity. Deletion of either gene results in a similar array of defects, including slow growth, dysregulated lipid homeostasis, impaired cell cycle progression (cut phenotype), abnormal cell morphology, perturbed transcriptomic and proteomic profiles, and compromised response to the stressors camptothecin and thiabendazole. Remarkably, the double deletion mutant does not exhibit a more severe phenotype compared to the single mutants. In addition, ChIP-nexus analysis reveals that both Cbf11 and Mga2 bind to nearly identical positions within the promoter regions of target genes. Interestingly, Mga2 binding appears to be dependent on the presence of Cbf11 and Cbf11 likely acts as a tether to DNA, while Mga2 is needed to activate the target genes. In addition, the study explores the distribution of Cbf11 and Mga2 homologs across fungi. The presence of both Cbf11 and Mga2 homologs in Basidiomycota contrasts with Ascomycota, which mostly lack Cbf11 but retain Mga2. This suggests an evolutionary rewiring of the regulatory circuitry governing lipid metabolism and mitotic fidelity. In conclusion, this study offers compelling support for Cbf11 and Mga2 functioning jointly to regulate lipid metabolism and mitotic fidelity in fission yeast.

Iron regulatory protein 1-deficient mice exhibit hypospermatogenesis.

Imbalances in testicular iron levels are linked to compromised sperm production and male infertility. Iron regulatory proteins (IRP) 1 and 2 play crucial roles in cellular iron regulation. We investigated the role of IRP1 on spermatogenesis using Irp1-deficient mice (Irp1-/-). Histological analysis of the testis of Irp1-/- mice revealed hypospermatogenesis with a significant reduction in the number of elongated spermatids and daily sperm production compared to wild-type (WT) mice. Flow cytometry of germ cells from WT and Irp1-/- mice showed reduction in spermatocytes and round and elongated spermatids in Irp1-/- mice, which was confirmed by histological and immunofluorescence quantification. Finally, stage VIII of spermatogenesis, crucial for spermatid maturation, was less frequent in Irp1-/- testicular cross-sections. Hypospermatogenesis worsened with age despite unchanged intratesticular iron levels. Mechanistically, this was due to increased oxidative stress indicated by elevated 8-Oxoguanine (8-OxoG) levels, a DNA lesion resulting from reactive oxygen species (ROS). Furthermore, bulk RNA-seq data indicated compromised DNA damage repair and cell cycle processes, including mitosis and meiosis in Irp1-/- mice, which may explain hypospermatogenesis. Our results suggest that IRP1 deletion leads to hypospermatogenesis due to impaired cell cycle progression, decreased DNA damage repair capacity, and oxidative damage. Altogether, this study uncovers a role for IRP1, independent of traditional mechanisms of iron regulation.

Abstract A062 Therapeutic targeting of the SAGA KAT module impairs MYCN-amplified neuroblastoma growth through reduction of the MYCN oncogenic gene expression program

Abstract Pediatric cancers are frequently driven by genomic alterations that result in aberrant transcription factor activity. While direct targeting of transcription factors is difficult, one method to circumvent this problem is to target co-factors and chromatin complexes that are necessary for their oncogenic function. To evaluate protein complex dependencies enriched in MYCN-amplified neuroblastoma, a disease of dysregulated development driven by aberrant expression of an oncogenic expression program, we curated a list of protein complexes using the CORUM database and mined the Dependency Map using single sample gene set enrichment analysis. This analysis identified the KAT module of the transcriptional coactivator Spt-Ada-Gcn5-acetyltransferase (SAGA) complex as a selective dependency in MYCN-amplified neuroblastoma. Loss of SAGA complex activity in neuroblastoma through both genetic knockout and induced protein degradation of the lysine acetyltransferase (KAT) module subunit TADA2B resulted in a global reduction of histone lysine acetylation and impaired neuroblastoma cell growth. Genetic knockout of TADA2B did not impair the growth of pediatric sarcoma cell lines, suggesting that SAGA loss-of-function is not broadly deleterious. Furthermore, SAGA loss-of-function reduced MYCN binding to chromatin, resulting in suppression of the MYCN-driven gene expression program and impaired cell cycle progression. Importantly, the SAGA complex is pharmacologically targetable in vitro and in vivo with GSK-699, a PROTAC that induces proteolysis of both KAT2A and KAT2B paralogs. As observed with genetic knockout studies, loss of SAGA activity through KAT2A/B degradation reduced the MYCN-driven transcriptional signature and impaired cell cycle progression. Our findings expand our understanding of the chromatin complexes that maintain the oncogenic transcriptional state in MYCN-amplified neuroblastoma and suggest therapeutic potential for inhibitors of SAGA KAT activity in MYCN-amplified neuroblastoma. Citation Format: Nathaniel W. Mabe, Clare F. Malone, Alexandra B. Forman, Gabriela Alexe, Kathleen L. Engel, Ying-Jiun C. Chen, Melinda Soeung, Silvi Salhotra, Allen Basanthakumar, Bin Liu, Sharon YR Dent, Kimberly Stegmaier. Therapeutic targeting of the SAGA KAT module impairs MYCN-amplified neuroblastoma growth through reduction of the MYCN oncogenic gene expression program [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pediatric Cancer Research; 2024 Sep 5-8; Toronto, Ontario, Canada. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl):Abstract nr A062.

CD24 affects the immunosuppressive effect of tumor-infiltrating cells and tumor resistance in a variety of cancers

BackgroundCluster of differentiation 24 (CD24) is a highly glycosylated glycosylphosphatidylinositol (GPI)-anchored surface protein, expressed in various tumor cells, as a "don't eat me" signaling molecule in tumor immune. This study aimed to investigate the potential features of CD24 in pan-cancer.MethodsThe correlations between 22 immune cells and CD24 expression were using TIMER analysis. R package “ESTIMATE” was used to predict the proportion of immune and stromal cells in pan-cancer. Spearman's correlation analysis was performed to evaluate the relationships between CD24 expression and immune checkpoints, chemokines, mismatch repair, tumor mutation burden and microsatellite instability, and qPCR and western blot were conducted to assess CD24 expression levels in liver hepatocellular carcinoma (LIHC). In addition, loss of function was performed for the biological evaluation of CD24 in LIHC.ResultsCD24 expression was positively correlated with myeloid cells, including neutrophils and myeloid-derived suppressor cells, in various tumors, such as BLCA, HNSC-HPV, HNSC, KICH, KIRC, KIRP, TGCT, THCA, THYM, and UCEC. In contrast, anti-tumor NK cells and NKT cells showed a negative association with CD24 expression in BRCA-Her2, ESCA, HNSC-HPV, KIRC, THCA, and THYM. The top three tumors with the highest correlation between CD24 and ImmuneScore were TGCT, THCA, and SKCM. Functional enrichment analysis revealed CD24 expression was negatively associated with various immune-related pathways. Immune checkpoints and chemokines also exhibited inverse correlations with CD24 in CESC, CHOL, COAD, ESCA, READ, TGCT, and THCA. Additionally, CD24 was overexpressed in most tumors, with high CD24 expression in BRCA, LIHC, and CESC correlating with poor prognosis. The TIDE database indicated tumors with high CD24 expression, particularly melanoma, were less responsive to PD1/PD-L1 immunotherapy. Finally, CD24 knockdown resulted in impaired proliferation and cell cycle progression in LIHC.ConclusionCD24 participates in regulation of immune infiltration, influences patient prognosis and serves as a potential tumor marker.

Rhus coriaria induces autophagic and apoptotic cell death in pancreatic cancer cells.

Background:Pancreatic cancer is a leading cause of cancer-related mortality worldwide with increasing global incidence. We previously reported the anticancer effect of Rhus coriaria ethanolic extract (RCE) in triple negative breast and colon cancer cells. Herein, we investigated the anticancer effect of RCE on human pancreatic cancer cells. Methods: Cell viability was measured using Cell Titer-Glo and staining of viable and dead cells based on differential permeability to two DNA binding dyes. Cell cycle distribution and annexin V staining was carried out in Muse cell analyzer. Protein level was determined by Western blot. Tumor growth was assessed by in ovo chick embryo chorioallantoic membrane assay. Results: We found that RCE significantly inhibited the viability and colony growth of pancreatic cancer cells (Panc-1, Mia-PaCa-2, S2-013, AsPC-1). The antiproliferative effects of RCE in pancreatic cancer cells (Panc-1 and Mia-PaCa-2) were mediated through induction of G1 cell cycle arrest, Beclin-1-independent autophagy, and apoptosis. RCE activated both the extrinsic and intrinsic pathways of apoptosis and regulated the Bax/Bcl-2 apoptotic switch. Mechanistically, we found that RCE inhibited the AKT/mTOR pathway, downstream of which, inactivation of the cell cycle regulator p70S6K and downregulation of the antiapoptotic protein survivin was observed. Additionally, we found that RCE-induced autophagy preceded apoptosis. Further, we confirmed the anticancer effect of RCE in a chick embryo xenograft model and found that RCE inhibited the growth of pancreatic cancer xenografts without affecting embryo survival. Conclusion: Collectively, our findings demonstrate that Rhus coriaria exerts potent anti-pancreatic cancer activity though cell cycle impairment, autophagy, and apoptosis, and is hence a promising source of anticancer phytochemicals.

Reversible acetylation of HDAC8 regulates cell cycle

HDAC8, a member of class I HDACs, plays a pivotal role in cell cycle regulation by deacetylating the cohesin subunit SMC3. While cyclins and CDKs are well-established cell cycle regulators, our knowledge of other regulators remains limited. Here we reveal the acetylation of K202 in HDAC8 as a key cell cycle regulator responsive to stress. K202 acetylation in HDAC8, primarily catalyzed by Tip60, restricts HDAC8 activity, leading to increased SMC3 acetylation and cell cycle arrest. Furthermore, cells expressing the mutant form of HDAC8 mimicking K202 acetylation display significant alterations in gene expression, potentially linked to changes in 3D genome structure, including enhanced chromatid loop interactions. K202 acetylation impairs cell cycle progression by disrupting the expression of cell cycle-related genes and sister chromatid cohesion, resulting in G2/M phase arrest. These findings indicate the reversible acetylation of HDAC8 as a cell cycle regulator, expanding our understanding of stress-responsive cell cycle dynamics.

UBXN3B is crucial for B lymphopoiesis

The ubiquitin regulatory X (UBX) domain-containing proteins (UBXNs) are putative adaptors for ubiquitin ligases and valosin-containing protein; however, their invivo physiological functions remain poorly characterised. We recently showed that UBXN3B is essential for activating innate immunity to DNA viruses and controlling DNA/RNA virus infection. Herein, we investigate its role in adaptive immunity. We evaluated the antibody responses to multiple viruses and pathogenesis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and influenza in tamoxifen-inducible global and constitutive B cell-specific Ubxn3b knockout mice; quantified various immune populations, B lineage progenitors/precursors, B cell receptor (BCR) signalling and apoptosis by flow cytometry, immunoblotting and immunofluorescence microscopy. We also performed bone marrow transfer, single-cell and bulk RNA sequencing. Both global and B cell-specific Ubxn3b knockout mice present a marked reduction in small precursor B-II (>60%), immature (>70%) and mature B (>95%) cell numbers. Transfer of wildtype bone marrow to irradiated global Ubxn3b knockouts restores normal B lymphopoiesis, while reverse transplantation does not. The mature B population shrinks rapidly with apoptosis and higher pro and activated caspase-3 protein levels were observed following induction of Ubxn3b knockout. Mechanistically, Ubxn3b deficiency leads to impaired pre-BCR signalling and cell cycle arrest. Ubxn3b knockout mice are highly vulnerable to respiratory viruses, with increased viral loads and prolonged immunopathology in the lung, and reduced production of virus-specific IgM/IgG. UBXN3B is essential for B lymphopoiesis by maintaining constitutive pre-BCR signalling and cell survival in a cell-intrinsic manner. United States National Institutes of Health grants, R01AI132526 and R21AI155820.

In Fanconi anemia, impaired accumulation of bone marrow neutrophils during emergency granulopoiesis induces hematopoietic stem cell stress

Fanconi Anemia (FA) is an inherited disorder of DNA-repair due to mutation in one of 20+ interrelated genes that repair intra-strand DNA crosslinks and rescue collapsed or stalled replication forks. The most common hematologic abnormality in FA is anemia, but progression to bone marrow failure (BMF), clonal hematopoiesis, or acute myeloid leukemia (AML) may also occur. In prior studies, we found that Fanconi DNA-repair is required for successful emergency granulopoiesis; the process for rapid neutrophil production during the innate immune response. Specifically, Fancc-/- mice did not develop neutrophilia in response to emergency granulopoiesis stimuli, but instead exhibited apoptosis of bone marrow hematopoietic stem cells (HSCs) and differentiating neutrophils. Repeated emergency granulopoiesis challenges induced BMF in most Fancc-/- mice, with AML in survivors. In contrast, we found equivalent neutrophilia during emergency granulopoiesis in Fancc-/-Tp53+/- mice and wild type (WT) mice, without BMF. Since termination of emergency granulopoiesis is triggered by accumulation of bone marrow neutrophils, we hypothesize neutrophilia protects Fancc-/-Tp53+/- bone marrow from the stress of a sustained inflammation that is experienced by Fancc-/- mice. In the current work, we found that blocking neutrophil accumulation during emergency granulopoiesis led to BMF in Fancc-/-Tp53+/- mice, consistent with this hypothesis. Blocking neutrophilia during emergency granulopoiesis in Fancc-/-Tp53+/- mice (but not WT) impaired cell cycle checkpoint activity, also found in Fancc-/- mice. Mechanisms for loss of cell cycle checkpoints during infections challenges may define molecular markers of FA progression, or suggest therapeutic targets for bone marrow protection in this disorder.

Comprehensive analysis of LMNB2 in pan-cancer and identification of its biological role in sarcoma.

Sarcoma (SARC) is a mesenchymal tumor which often responds poorly to systemic therapy. It is therefore important to look for possible biological markers that could tell the prognosis and the progression of SARC. A combined evaluation of the Cancer Genome Atlas (TCGA) and genotypic tissue expression (GTEx) portal was used to analyzeLMNB2 expression level in different types of cancer. Kaplan-Meier survival analysis was performed to examine LMNB2 predictive value in over-all survival rate and disease-free survival rate. The association among LMNB2 expression level and immune cell infiltration, microsatellite instability (MSI) and tumor mutational burden (TMB) were analyzed. GO and KEGG enrichment analysis were performed to predicate LMNB2 biological functions. The biological function of LMNB2 was estimated by MTT and flow cytometry assay. Additionally, western blot assay was used to examine protein expression levels. Increased LMNB2 expression was related with worsened cancer type-dependent survival. A relation between LMNB2 expression levels and immune cell infiltration was found. GO and KEGG enrichment analysis indicated that LMNB2 was involved in a series of pathways. Biology function assays revealed that down-regulation of LMNB2 impaired proliferation and cell cycle distribution. At the mechanical level, LMNB2 acts as a regulator of cyclinD1 and cyclinE1. Altogether, these data suggest that LMNB2 may serve as a tumor promoter and could be a possible target for cancer therapy.

GATA2 heterozygosity causes an epigenetic feedback mechanism resulting in myeloid and erythroid dysplasia.

The transcription factor GATA2 has a pivotal role in haematopoiesis. Heterozygous germline GATA2 mutations result in a syndrome characterized by immunodeficiency, bone marrow failure and predispositions to myelodysplastic syndrome (MDS) and acute myeloid leukaemia. Clinical symptoms in these patients are diverse and mechanisms driving GATA2-related phenotypes are largely unknown. To explore the impact of GATA2 haploinsufficiency on haematopoiesis, we generated a zebrafish model carrying a heterozygous mutation of gata2b (gata2b+/-), an orthologue of GATA2. Morphological analysis revealed myeloid and erythroid dysplasia in gata2b+/- kidney marrow. Because Gata2b could affect both transcription and chromatin accessibility during lineage differentiation, this was assessed by single-cell (sc) RNA-seq and single-nucleus (sn) ATAC-seq. Sn-ATAC-seq showed that the co-accessibility between the transcription start site (TSS) and a -3.5-4.1 kb putative enhancer was more robust in gata2b+/- zebrafish HSPCs compared to wild type, increasing gata2b expression and resulting in higher genome-wide Gata2b motif use in HSPCs. As a result of increased accessibility of the gata2b locus, gata2b+/- chromatin was also more accessible during lineage differentiation. scRNA-seq data revealed myeloid differentiation defects, that is, impaired cell cycle progression, reduced expression of cebpa and cebpb and increased signatures of ribosome biogenesis. These data also revealed a differentiation delay in erythroid progenitors, aberrant proliferative signatures and down-regulation of Gata1a, a master regulator of erythropoiesis, which worsened with age. These findings suggest that cell-intrinsic compensatory mechanisms, needed to obtain normal levels of Gata2b in heterozygous HSPCs to maintain their integrity, result in aberrant lineage differentiation, thereby representing a critical step in the predisposition to MDS.

The KAT module of the SAGA complex maintains the oncogenic gene expression program in MYCN-amplified neuroblastoma.

Pediatric cancers are frequently driven by genomic alterations that result in aberrant transcription factor activity. Here, we used functional genomic screens to identify multiple genes within the transcriptional coactivator Spt-Ada-Gcn5-acetyltransferase (SAGA) complex as selective dependencies for MYCN-amplified neuroblastoma, a disease of dysregulated development driven by an aberrant oncogenic transcriptional program. We characterized the DNA recruitment sites of the SAGA complex in neuroblastoma and the consequences of loss of SAGA complex lysine acetyltransferase (KAT) activity on histone acetylation and gene expression. We demonstrate that loss of SAGA complex KAT activity is associated with reduced MYCN binding on chromatin, suppression of MYC/MYCN gene expression programs, and impaired cell cycle progression. Further, we showed that the SAGA complex is pharmacologically targetable in vitro and in vivo with a KAT2A/KAT2B proteolysis targeting chimeric. Our findings expand our understanding of the histone-modifying complexes that maintain the oncogenic transcriptional state in this disease and suggest therapeutic potential for inhibitors of SAGA KAT activity in MYCN-amplified neuroblastoma.

Pollutants, microbiota and immune system: frenemies within the gut.

Pollution is a critical concern of modern society for its heterogeneous effects on human health, despite a widespread lack of awareness. Environmental pollutants promote several pathologies through different molecular mechanisms. Pollutants can affect the immune system and related pathways, perturbing its regulation and triggering pro-inflammatory responses. The exposure to several pollutants also leads to alterations in gut microbiota with a decreasing abundance of beneficial microbes, such as short-chain fatty acid-producing bacteria, and an overgrowth of pro-inflammatory species. The subsequent intestinal barrier dysfunction, together with oxidative stress and increased inflammatory responses, plays a role in the pathogenesis of gastrointestinal inflammatory diseases. Moreover, pollutants encourage the inflammation-dysplasia-carcinoma sequence through various mechanisms, such as oxidative stress, dysregulation of cellular signalling pathways, cell cycle impairment and genomic instability. In this narrative review, we will describe the interplay between pollutants, gut microbiota, and the immune system, focusing on their relationship with inflammatory bowel diseases and colorectal cancer. Understanding the biological mechanisms underlying the health-to-disease transition may allow the design of public health policies aimed at reducing the burden of disease related to pollutants.

Abstract 4642: Fatty acid synthase as a novel prognostic biomarker and a potential therapeutic target in diffuse malignant peritoneal mesothelioma

Abstract Diffuse malignant peritoneal mesothelioma (DMPM) is a rare and locally aggressive tumor with a dismal prognosis. The availability of new therapies and biomarkers for patients’ selection is still an urgent need. Altered lipid metabolism, which has been reported in several tumors, has not yet been studied in DMPM. By comparatively analyzing gene expression profiles of tumors form relapsed (n=18) and non-relapsed (n=18) DMPM patients, we initially found that fatty acid synthase (FASN) was up-modulated in relapsed tumors, with a significant linear correlation between FASN expression and shorter patient relapse-free survival (RFS), suggesting a potential role of FASN in DMPM progression. The prognostic significance of FASN was further assessed in a cohort of 80 DMPM patients who underwent cytoreductive surgery combined with hyperthermic intraperitoneal chemotherapy. Our results indicated that high FASN staining was significantly associated with reduced RFS (hazard ration (HR): 1.930; p=0.014) and Overall Survival (OS) (HR: 1.854; p=0.032) as assessed by immunohistochemistry in tissues microarray samples. The prognostic value of FASN, along with Ki67 staining and patient age, was also maintained in multivariate analysis in terms of both RFS (HR: 2.240; p=0.007) and OS (HR: 2.246; p=0.014). To validate FASN as a therapeutic target, we investigated the cytotoxic effects of non-selective (orlistat) and selective (cerulenin and C75) FASN inhibitors on patient-derived DMPM cell lines, both as single agents and in combination with selinexor -a selective inhibitor of the exportin chromosome maintenance protein. FASN pharmacological inhibition in DMPM cells resulted in a significant reduction of cell proliferation, especially upon C75 exposure. In combination experiments, we observed a synergistic activity of FASN inhibitors and selinexor, as determined by Chou and Talalay method. Through western blotting and flow cytometry analysis, we gained further insight into the mechanisms by which FASN inhibitors and selinexor synergize to reduce DMPM cell proliferation. Compared to single agents, the combined treatments resulted in increased apoptosis response and cell cycle impairment, as indicated by caspase-dependent apoptosis activation and cell accumulation in the G2-phase. Overall, our results support the relevance of FASN as a prognostic biomarker for DMPM patients and underscore its potential as a novel therapeutic target. Citation Format: Valentina Doldi, Silvia Martini, Chiara Maura Ciniselli, Alessia Beretta, Marcello Deraco, Shigeki Kusamura, Dario Baratti, Paolo Gandellini, Paolo Verderio, Nadia Zaffaroni. Fatty acid synthase as a novel prognostic biomarker and a potential therapeutic target in diffuse malignant peritoneal mesothelioma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4642.

Abstract B012: Transcriptomic insights reveal role of BCL2 proteins in replication checkpoint inhibitor response

Abstract B012: Transcriptomic insights reveal role of BCL2 proteins in replication checkpoint inhibitor response

NCDN is a Potential Biomarker and Therapeutic Target for Glioblastoma.

Background: Glioblastoma (GBM) is a type of central nervous system malignancy. In our study, we determined the effect of NCDN in GBM patients through The Cancer Genome Atlas (TCGA) data analysis, and studied the effects of NCDN on GBM cell function to estimate its potential as a therapeutic target. Methods: Gene expression profiles of glioblastoma cohort were acquired from TCGA database and analyzed to look for central genes that may serve as GBM therapeutic targets. Then the cell function of NCDN in glioblastoma cell was explored through in vitro cell experiments. Results: Through gene ontology (GO) analysis, weighted gene co-expression network analysis (WGCNA), and survival analysis, we identified three key genes (NCDN, PAK1 and SPRYD3) associated with poor prognosis in glioblastoma. In vitro experiments showed impaired cell migration, apoptosis, and cell cycle arrest in NCDN knockdown cells. Conclusion: NCDN affects the progress and prognosis of glioblastoma by promoting cell migration and inhibiting apoptosis.

Молекулярно-клеточные механизмы влияния вирусов папилломы человека на чувствительность злокачественных опухолей к лучевой терапии. Обзор

The article presents review of literature data and results of our own studies devoted to elucidating the molecular and cellular mechanisms of influence of human papillomaviruses (HPV) on the effectiveness of radiation therapy (RT) of HPV-associated malignant neoplasms, including, first of all, cervical and oropharyngeal cancer. The data are systematized from the point of view of HPV influence on 6 main factors (so-called 6Rs), determining the response of cells/tissues to fractionated irradiation and, ultimately, affecting the effectiveness of RT (reparation, reoxygenation, redistribution across cell cycle phases, repopulation, radiosensitivity, reactivation of the immune response). Compared with HPV-negative tumors, HPV-positive tumors demonstrate higher sensitivity to sparsely ionizing radiation due to decreased efficiency of homologous DNA damage repair (R1), higher oxygenation and suppression of antioxidant defense (R2), impaired cell cycle control (R3), features of cancer stem cell regulation that ensure post-radiation repopulation (R4), and higher intrinsic radiosensitivity (R5). Viral proteins E6 and E7 have a broad spectrum of action on the state of innate and adaptive antitumor immunity, therefore significant differences were demonstrated in immunological profile of HPV-positive and HPV-negative tumors, as well as in efficiency of combined radioimmunotherapy of cancer patients with different HPV status. However, the effects of HPV on reactivation of antitumor immune response (R6) during fractionated irradiation has not been sufficiently studied. Thus, HPV have a significant impact on almost all known factors (at least 5 out of 6 Rs) determining the effectiveness of RT using sparsely ionizing radiation. Analysis of the mechanisms of such impact suggests that differences in effectiveness of RT of HPV-positive and HPV-negative tumors can, at least partially e leveled out when using densely ionizing radiation.

Age-related changes in human bone marrow mesenchymal stromal cells: morphology, gene expression profile, immunomodulatory activity and miRNA expression.

Mesenchymal stromal cells (MSC) are one of the main cellular components of bone marrow (BM) microenvironment. MSC play a key role in tissue regeneration, but they are also capable of immunomodulating activity. With host aging, MSC undergo age-related changes, which alter these functions, contributing to the set-up of "inflammaging", which is known to be the basis for the development of several diseases of the elderly, including cancer. However, there's few data investigating this facet of MSC, mainly obtained using murine models or replicative senescence. The aim of this research was to identify morphological, molecular and functional alterations of human bone marrow-derived MSC from young (yBM-MSC) and old (oBM-MSC) healthy donors. MSC were identified by analysis of cell-surface markers according to the ISCT criteria. To evaluate response to inflammatory status, MSC were incubated for 24h in the presence of IL-1β, IFN-α, IFN-ɣ and TNF-α. Macrophages were obtained by differentiation of THP-1 cells through PMA exposure. For M1 polarization experiments, a 24h incubation with LPS and IFN-ɣ was performed. MSC were plated at the bottom of the co-culture transwell system for all the time of cytokine exposure. Gene expression was evaluated by real-time PCR after RNA extraction from BM-MSC or THP-1 culture. Secreted cytokines levels were quantitated through ELISA assays. Aging MSC display changes in size, morphology and granularity. Higher levels of β-Gal, reactive oxygen species (ROS), IL-6 and IL-8 and impaired colony-forming and cell cycle progression abilities were found in oBM-MSC. Gene expression profile seems to vary according to subjects' age and particularly in oBM-MSC seem to be characterized by an impaired immunomodulating activity, with a reduced inhibition of macrophage M1 status. The comparative analysis of microRNA (miRNA) expression in yBM-MSC and oBM-MSC revealed a significant difference for miRNA known to be involved in macrophage polarization and particularly miR-193b-3p expression is strongly increased after co-culture of macrophages with yBM-MSC. There are profound differences in terms of morphology, gene and miRNA expression and immunomodulating properties among yBM-MSC and oBM-MSC, supporting the critical role of aging BM microenvironment on senescence, immune-mediated disorders and cancer pathogenesis.