Cell Cycle Checkpoint Research Articles

Construction and characterization of a novel secreted MsC-CAR-T cell in solid tumors

The CD47-SIRPα signaling has been acknowledged as a significant immune checkpoint and CD47 blocking has been proved as a potential therapeutic strategy for the treatment of solid tumor. However, the potential application of CAR-T cells secreted antibody fragment simultaneously in solid tumor is rarely explored. In this study, we searched bioinformatic databases and investigated the characteristics of CD47 in solid tumors. Then we consulted bioinformatic databases to design, optimize and construct a novel MsC-CAR which could target MAGE-A1 and self-secrete CD47-scFv. The engineering T cells containing MsC-CAR were transfected, verified and characterized. The tumor-inhibitory role of MsC-CART cells was further determined in vitro and in vivo. The results showed that MsC-CARs were successfully constructed and MsC1-CARs demonstrated the preferable features of recognizing MAGE-A1 and secreting CD47-scFv. Engineering T cells transfecting with MsC1-CAR (MsC1-CART cells) exerted the prominent tumor-inhibitory effectiveness, both in different cancer cell lines and LUAD xenograft tumors. The present data highlighted that MsC1-CART cells elaborately combined the adoptive cellular immunotherapy and immune checkpoint inhibitor therapy, may represent a new direction for the treatment of MAGE-A1 positive solid tumors.

Activation of Stimulator of Interferon Genes (STING): Promising Strategy to Overcome Immune Resistance in Prostate Cancer.

Prostate cancer (PCa) is the most frequent and second-lethal cancer among men. Despite considerable efforts to explore treatments like autologous cellular immunotherapy and immune checkpoint inhibitors, their success remains limited. The intricate tumor microenvironment (TME) and its interaction with the immune system pose significant challenges in PCa treatment. Consequently, researchers have directed their focus on augmenting the immune system's anti-tumor response by targeting the STimulator of the Interferon Genes (STING) pathway. The STING pathway is activated when foreign DNA is detected in the cytoplasm of innate immune cells, resulting in the activation of endoplasmic reticulum (ER) STING. This, in turn, triggers an augmentation of signaling, leading to the production of type I interferon (IFN) and other pro-inflammatory cytokines. Numerous studies have demonstrated that activation of the STING pathway induces immune system rejection and targeted elimination of PCa cells. Researchers have been exploring various methods to activate the STING pathway, including the use of bacterial vectors to deliver STING agonists and the combination of radiation therapy with STING agonists. Achieving effective radiation therapy with minimal side effects and optimal anti-tumor immune responses necessitates precise adjustments to radiation dosing and fractionation schedules. This comprehensive review discusses promising findings from studies focusing on activating the STING pathway to combat PCa. The STING pathway exhibits the potential to serve as an effective treatment modality for PCa, offering new hope for improving the lives of those affected by this devastating disease.

C/EBPβ-dependent autophagy inhibition hinders NK cell function in cancer

NK cells are endowed with tumor killing ability, nevertheless most cancers impair NK cell functionality, and cell-based therapies have limited efficacy in solid tumors. How cancers render NK cell dysfunctional is unclear, and overcoming resistance is an important immune-therapeutic aim. Here, we identify autophagy as a central regulator of NK cell anti-tumor function. Analysis of differentially expressed genes in tumor-infiltrating versus non-tumor NK cells from our previously published scRNA-seq data of advanced human prostate cancer shows deregulation of the autophagic pathway in tumor-infiltrating NK cells. We confirm this by flow cytometry in patients and in diverse cancer models in mice. We further demonstrate that exposure of NK cells to cancer deregulates the autophagic process, decreases mitochondrial polarization and impairs effector functions. Mechanistically, CCAAT enhancer binding protein beta (C/EBPβ), downstream of CXCL12-CXCR4 interaction, acts as regulator of NK cell metabolism. Accordingly, inhibition of CXCR4 and C/EBPβ restores NK cell fitness. Finally, genetic and pharmacological activation of autophagy improves NK cell effector and cytotoxic functions, which enables tumour control by NK and CAR-NK cells. In conclusion, our study identifies autophagy as an intracellular checkpoint in NK cells and introduces autophagy regulation as an approach to strengthen NK-cell-based immunotherapies.

Exploring the role of PARP1 inhibition in enhancing antibody–drug conjugate therapy for acute leukemias: insights from DNA damage response pathway interactions

BackgroundThe introduction of antibody–drug conjugates represents a significant advancement in targeted therapy of acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL). Our study aims to investigate the role of the DNA damage response pathway and the impact of PARP1 inhibition, utilizing talazoparib, on the response of AML and ALL cells to Gemtuzumab ozogamicin (GO) and Inotuzumab ozogamicin (INO), respectively.MethodsAML and ALL cells were treated with GO, INO and γ-calicheamicin in order to induce severe DNA damage and activate the G2/M cell-cycle checkpoint in a dose- and time-dependent manner. The efficacy of PARP1 inhibitors and, in particular, talazoparib in enhancing INO or GO against ALL or AML cells was assessed through measurements of cell viability, cell death, cell cycle progression, DNA damage repair, accumulation of mitotic DNA damage and inhibition of clonogenic capacity.ResultsWe observed that both ALL and AML cell lines activate the G2/M cell-cycle checkpoint in response to γ-calicheamicin-induced DNA damage, highlighting a shared cellular response mechanism. Talazoparib significantly enhanced the efficacy of INO against ALL cell lines, resulting in reduced cell viability, increased cell death, G2/M cell-cycle checkpoint override, accumulation of mitotic DNA damage and inhibition of clonogenic capacity. Strong synergism was observed in primary ALL cells treated with the combination. In contrast, AML cells exhibited a heterogeneous response to talazoparib in combination with GO. Our findings suggest a potential link between the differential responses of ALL and AML cells to the drug combinations and the ability of talazoparibto override G2/M cell-cycle arrest induced by antibody–drug conjugates.ConclusionPARP1 emerges as a key player in the response of ALL cells to INO and represents a promising target for therapeutic intervention in this leukemia setting. Our study sheds light on the intricate interplay between the DNA damage response pathway, PARP1 inhibition, and response of γ-calicheamicin-induced DNA damages in AML and ALL. These findings underscore the importance of targeted therapeutic strategies and pave the way for future research aimed at optimizing leukemia treatment approaches.

Chronic inflammation deters natural killer cell fitness and cytotoxicity in myeloid leukemia

AbstractNatural killer (NK) cells play an integral role in immunosurveillance against myeloid malignancies, with their mature phenotype and abundance linked to prolonged treatment-free remission in chronic myeloid leukemia (CML). However, NK cell function is suppressed during the disease, and the orchestrators of this impairment are not fully understood. Using a chimeric BCR::ABL1+ CML mouse model, we characterized the impact of the leukemic microenvironment on NK cell function. We showed that NK cells have reduced counts, immature phenotype, poor cytotoxicity, and altered expression of activating and inhibitory receptors in CML mice, which revert to a steady state upon BCR::ABL1 inhibition. Single-cell RNA sequencing revealed an inflammatory cytokine response in CML-exposed NK cells, highlighted by the tumor necrosis factor α (TNFα)-induced gene signature, upregulation of TNFα receptor 2, and enrichment of SOCS family genes such as Cish, the critical NK cell checkpoint. Ex vivo exposure of healthy NK cells to leukemic soluble factors compromised target-specific NK cell degranulation, which was partially rescued by targeting Cish or TNFα. In alignment with these findings, NK cells from healthy donors displayed suppressed cytotoxicity when exposed to plasma from untreated patients with CML, with a partial restoration upon Cish or TNFα inhibition. Furthermore, NK cells from newly diagnosed patients with CML predestined for blast crisis showed an enrichment of the TNFα-induced proinflammatory gene signature identified in CML mice. These results suggest that targeting inflammatory signaling could enhance NK cell-based immunotherapies for CML.

TET2 promotes tumor antigen presentation and T cell IFN-γ, which is enhanced by vitamin C.

Immune evasion by tumors is promoted by low T cell infiltration, ineffective T cell activity directed against the tumor, and reduced tumor antigen presentation. The TET2 DNA dioxygenase gene is frequently mutated in hematopoietic malignancies and loss of TET enzymatic activity is found in a variety of solid tumors. We showed previously that vitamin C (VC), a cofactor of TET2, enhances tumor-associated T cell recruitment and checkpoint inhibitor therapy responses in a TET2-dependent manner. Using single-cell RNA sequencing (scRNA-seq) analysis performed on B16-OVA melanoma tumors, we have shown here that an additional function for TET2 in tumors is to promote expression of certain antigen presentation machinery genes, which is potently enhanced by VC. Consistently, VC promoted antigen presentation in cell-based and tumor assays in a TET2-dependent manner. Quantifying intercellular signaling from the scRNA-seq dataset showed that T cell-derived IFN-γ-induced signaling within the tumor and tumor microenvironment requires tumor-associated TET2 expression, which is enhanced by VC treatment. Analysis of patient tumor samples indicated that TET activity directly correlates with antigen presentation gene expression and with patient outcomes. Our results demonstrate the importance of tumor-associated TET2 activity as a critical mediator of tumor immunity, which is augmented by high-dose VC therapy.

Cryo-EM structures of apo-APC/C and APC/CCDH1:EMI1 complexes provide insights into APC/C regulation

APC/C is a multi-subunit complex that functions as a master regulator of cell division. It controls progression through the cell cycle by timely marking mitotic cyclins and other cell cycle regulatory proteins for degradation. The APC/C itself is regulated by the sequential action of its coactivator subunits CDC20 and CDH1, post-translational modifications, and its inhibitory binding partners EMI1 and the mitotic checkpoint complex. In this study, we took advantage of developments in cryo-electron microscopy to determine the structures of human APC/CCDH1:EMI1 and apo-APC/C at 2.9 Å and 3.2 Å resolution, respectively, providing insights into the regulation of APC/C activity. The high-resolution maps allow the unambiguous assignment of an α-helix to the N-terminus of CDH1 (CDH1α1) in the APC/CCDH1:EMI1 ternary complex. We also identify a zinc-binding module in APC2 that confers structural stability to the complex, and we confirm the presence of zinc ions experimentally. Finally, due to the higher resolution and well defined density of these maps, we are able to build, aided by AlphaFold predictions, several intrinsically disordered regions in different APC/C subunits that likely play a role in proper APC/C assembly and regulation of its activity.

Determining the rate-limiting processes for cell division in Escherichia coli

A critical cell cycle checkpoint for most bacteria is the onset of constriction when the septal peptidoglycan synthesis starts. According to the current understanding, the arrival of FtsN to midcell triggers this checkpoint in Escherichia coli. Recent structural and in vitro data suggests that recruitment of FtsN to the Z-ring leads to a conformational switch in actin-like FtsA, which links FtsZ protofilaments to the cell membrane and acts as a hub for the late divisome proteins. Here, we investigate this putative pathway using in vivo measurements and stochastic cell cycle modeling at moderately fast growth rates. Quantitatively upregulating protein concentrations and determining the resulting division timings shows that FtsN and FtsA numbers are not rate-limiting for the division in E. coli. However, at higher overexpression levels, they affect divisions: FtsN by accelerating and FtsA by inhibiting them. At the same time, we find that the FtsZ numbers in the cell are one of the rate-limiting factors for cell divisions in E. coli. Altogether, these findings suggest that instead of FtsN, accumulation of FtsZ in the Z-ring is one of the main drivers of the onset of constriction in E. coli at faster growth rates.

Abstract 4141496: Methylation changes in monocytes of type 2 diabetes patients with cardiovascular disease are associated with apoptosis and inflammation pathways.

Background: Monocytes have been implicated in the initiation and progression of cardiovascular (CV) complications of type 2 diabetes (T2D). Aim: We investigated diabetes-induced methylation changes and enriched pathways in circulating monocytes of T2D patients. We compared T2D vs. non-T2D participants and analyzed T2D patients according to diabetes control. Further, we assessed methylation changes in a subset of patients with poor diabetes control and high CV risk following a 6-month treatment intensification. Methods: We recruited consecutively 200 participants, 160 with T2D and 40 non-diabetes controls. Circulating monocytes were sorted using the FACSAria2 ™ cell sorter. Samples were sequenced using enhanced reduced representation bisulfite sequencing. Methylation data was processed with Lumi and limma R packages to obtain batch and covariate corrected differential expression values for the indicated comparisons. Ingenuity Pathway Analysis (Qiagen) was used to identify enriched pathways for each tested condition. Differentially methylated genes used for pathway analysis were those with a p-value < 0.05 and an absolute logFC value ≥ 0.5. Results: There were 1122 differentially methylated genes when comparing T2D to non-T2D patients. Among the top five enriched canonical pathways, apoptosis signaling was predicted to be activated, while the RHO GTPase cycle and LPS-stimulated MAPK signaling pathways were predicted to be inhibited. Within patients with diabetes, there were 1670 differentially methylated genes comparing those with poor control (HbA1c ≥ 7%) vs. good control (HbA1c<7%). Among the top five enriched pathways, synthesis of DNA, DNA replication signaling, and cell cycle checkpoints were activated while inhibition of ARE-mediated mRNA degradation pathway was inhibited. In patients who responded to treatment intensification (Δ HbA1c = -1.5%, p= 0.02), 1377 differentially methylated genes and differentially inhibited pathways such as non-homologous end-joining and cellular response to heat stress were identified. In non-responders, we identified 1582 differentially methylated genes and activated pathways, including inhibition of mRNA degradation pathways and p14/p19 ARF signaling. Conclusion: Treatment intensification in T2D patients with CVD and poor control showed the presence of differentially methylated genes affecting pathways regulating cell proliferation and inflammation and are known to be associated with diabetic CVD complications.

Dissecting the Cell-Killing Mechanisms of Hydroxyurea Using Spot Assays.

Hydroxyurea is an inhibitor of ribonucleotide reductase and is commonly used in laboratories to induce replication stress or arrest cells in the S phase for cell cycle or checkpoint studies. However, hydroxyurea also causes side effects such as oxidative stress, particularly under chronic exposure conditions. This complicates the interpretation of the cell-killing mechanisms, particularly in a previously uncharacterized mutant, and thus hampers the analyses. Here, we describe a few easy and simple spot assays in fission yeast that allow dissecting the cell-killing mechanisms of hydroxyurea.

A Rapidly Inducible DNA Double-Strand Break to Monitor Telomere Formation, DNA Repair, and Checkpoint Activation.

The study of processes that govern genome integrity has been augmented by the ability to create a precise DNA double-strand break (DSB) in a short period of time that allows the kinetics of DNA metabolism and protein recruitment to be followed. Defined DSBs are made by expressing endonucleases with long recognition sites that are rare or absent in the genome, and require that the endonuclease is only active when induced. Research in this area in Schizosaccharomyces pombe was limited because rapidly inducible promoters were not available until around 2005, and several rapidly inducible DSB systems are now available. Here, we describe a system to rapidly induce a modified I-SceI endonuclease that can generate a DSB 20min after induction. I-SceI has no recognition sites in the S. pombe genome, allowing the introduction of complex substrates to monitor the effects of a new DSB in real time. This chapter describes how I-SceI can be most efficiently induced and a simple cell length measurement assay to monitor cell cycle checkpoint activation from a single DSB.

DNA damage response inhibitors in cancer therapy: lessons from the past, current status and future implications.

The DNA damage response (DDR) is a network of proteins that coordinate DNA repair and cell-cycle checkpoints to prevent damage being transmitted to daughter cells. DDR defects lead to genomic instability, which enables tumour development, but they also create vulnerabilities that can be used for cancer therapy. Historically, this vulnerability has been taken advantage of using DNA-damaging cytotoxic drugs and radiotherapy, which are more toxic to tumour cells than to normal tissues. However, the discovery of the unique sensitivity of tumours defective in the homologous recombination DNA repair pathway to PARP inhibition led to the approval of six PARP inhibitors worldwide and to a focus on making use of DDR defects through the development of other DDR-targeting drugs. Here, we analyse the lessons learnt from PARP inhibitor development and how these may be applied to new targets to maximize success. We explore why, despite so much research, no other DDR inhibitor class has been approved, and only a handful have advanced to later-stage clinical trials. We discuss why more reliable predictive biomarkers are needed, explore study design from past and current trials, and suggest alternative models for monotherapy and combination studies. Targeting multiple DDR pathways simultaneously and potential combinations with anti-angiogenic agents or immune checkpoint inhibitors are also discussed.

CSIG-09. BEYOND SINGLE AGENTS: EXPLORING THE POTENTIAL OF ABEMACICLIB IN COMBINATION WITH PANOBINOSTAT FOR IMPROVED GLIOMA TREATMENT

Abstract BACKGROUND Glioblastoma is the most common primary central nervous system tumour with a median survival of less than 15 months. Addressing the underlying redundant, and converging signaling pathways necessitates the utilization of small molecule inhibitors capable of simultaneous targeting and inhibition. In glioma, the aberrant CDK4/6-Rb pathway dysregulation resulting in disruption of cell cycle checkpoint progression can lead to uncontrolled cell division, a hallmark of cancer. The neuro-pharmacokinetics of abemaciclib, a Cyclin-dependent kinase inhibitor, is being currently investigated in phase 1 clinical trials by National Cancer Institue, [NCT05413304]. The importance of panobinostat as a Histone deacetylase inhibitor and potentiating the effects of various small molecular inhibitors in published literature is paramount. This study is based on investigating ways to overcome resistance by exploring the synergistic cytotoxic effects of abemaciclib in combination with panobinostat in glioma. METHODS We investigated the antiproliferative effects of abemaciclib and panobinostat on glioma cells using an MTS cell proliferation assay. Inhibitor combination analysis was done using, SYNERGYFINDER via zip-model. Flow cytometry with Annexin V staining further assessed cell death and apoptosis induced. RESULTS The antiproliferative effects of abemaciclib, alone and in combination with panobinostat, in pediatric lines (KNS 42, SJG2), and adult human glioblastoma line, SF188 exhibited lower IC50 as compared to adult high grade glioma lines (LN 18, LNZ 308). Synergy analysis revealed a strong cytotoxic effect in KNS 42 and SF 188 cells treated with the combination. Flow cytometric analysis indicated that the combination therapy induced significant cell death only in a subset of cell lines- KNS 42 and SF 188, suggesting underlying genetic heterogeneity influences treatment response, warranting further mechanistic studies. CONCLUSION Combination therapies using abemaciclib and panobinostat, targeting CDK4/6 and histone deacetylation pathways, show promise against aggressive and treatment-resistant gliomas. Further investigation into these combination approaches is crucial to understand resistant mechanisms, optimize efficacy, and establish their clinical efficacy for improving glioma patient outcomes.

EPCO-04. H3F3A K27M MUTATION DRIVES A REPRESSIVE TRANSCRIPTOME VIA REDUCED SERINE 31 PHOSPHORYLATION BY MODULATING CHROMATIN ACCESSIBILITY, INDEPENDENT OF H3K27ME3 IN DIFFUSE MIDLINE GLIOMA

Abstract Heterozygous H3.3 K27M mutations are central to the pathogenesis of diffuse midline gliomas (DMG), causing a global reduction in H3K27 trimethylation (H3K27me3) and subsequent epigenetic dysregulation. H3.3 contains a unique Serine 31 (S31) phosphorylation site crucial for mitotic checkpoint regulation. In DMG cells, reduced mitotic S31 phosphorylation correlates with chromosomal instability and aneuploidy. Using a mouse model, we demonstrate that both H3.3K27M and H3.3S31A mutations promote high-grade glioma development, whereas wild-type H3.3 does not. Importantly, S31A, which maintains normal K27me, suggests that S31 phosphorylation loss alone is oncogenic. The H3.3K27M mutation disrupts epigenetic regulation by inhibiting the Polycomb Repressive Complex 2 (PRC2), leading to decreased H3K27me3 and unintended gene induction. Concurrently, K27M exerts a compensatory repressive effect on the transcriptome, mediated by reduced S31 phosphorylation, independent of PRC2 activity. Using CRISPR-engineered isogenic DMG cells and analyzing the transcriptome and chromatin accessibility with RNA-seq and ATAC-seq, we found that the K27M mutation produces a balanced gene expression profile, while PRC2 loss primarily leads to gene induction. Notably, cells with S31A mutations also maintain this balanced profile, linking the PRC2-independent effect of K27M to reduced S31 phosphorylation. Conversely, cells with wild-type K27 but S31A mutation show a repressive genomic state, evidenced by an up/down gene ratio of 0.75, owing to functional PRC2. We further show that the genes uniquely dysregulated by K27M or S31A, independent of PRC2, overlap significantly, with dysregulated genes displaying altered chromatin accessibility. This suggests that the effect of K27M and S31A mutations on gene regulation is primarily due to changes in chromatin state. This complex interplay points to targeting K27M-associated pathways, particularly S31 phosphorylation, as a promising therapeutic avenue in DMG, a malignancy with fewer effective treatments and dismal prognosis.

Molecular basis for the disease-modifying effects of belimumab in systemic lupus erythematosus and molecular predictors of early response: blood transcriptome analysis implicates the innate immunity and DNA damage response pathways

ObjectivesBelimumab is a putative disease-modifying agent in systemic lupus erythematosus (SLE), yet the molecular underpinnings of its effects and the ability to predict early clinical response remain unexplored. To address...

A pan-cancer study of ADAM9’s immunological function and prognostic value particularly in liver cancer

A pan-cancer analysis summarizing the overall changes in mRNA and protein stability of ADM9, as well as its oncogenic function on immune cell line modulation and checkpoints within the tumor microenvironment (TME), is lacking, despite the fact that ADM9 up-regulation is correlated with the progression of many cancers. Therefore, in this study, we comprehensively analyzed the role of ADAM9 expression and its prognostic value in different cancers to fill this gap. Multiple bioinformatics databases such as Cancer Genome Atlas (TCGA), Genotype-Tissue Expression (GTEx), and Clinical Proteomic Tumor Analysis Consortium (CPTAC) were used to evaluate the ADAM9 genetic alternation, phosphorylation, and methylation, and indicated highly positive correlated genes that might play a critical interaction with ADAM9 and their molecular function with GO analysis. We also evaluate the effect of higher ADAM9 with prominent immune modulatory genes and immune infiltration especially in liver cancer pathogenesis stimulates lower NK cell effector functions based on its role in MICA shedding and increasing the Tregs infiltration. Immunohistochemistry (IHC) staining from 90 pathologically verified samples proved the positive correlation between ADAM9 and tumor stages and proved the higher expression of ADAM9 correlated genes (SNX9, APP, TNF, CDH1, ITGAV, MAD2L2) in HCC pathogenesis. In conclusion, this pan-cancer study provides a comprehensive understanding of the prognostic value of ADAM9 in various tumors emphasizing its importance to be considered as an innovative treatment approach, especially in tumor immunity shortly.

Characterising Cancer Cell Responses to Cyclic Hypoxia Using Mathematical Modelling

In vivo observations show that oxygen levels in tumours can fluctuate on fast and slow timescales. As a result, cancer cells can be periodically exposed to pathologically low oxygen levels; a phenomenon known as cyclic hypoxia. Yet, little is known about the response and adaptation of cancer cells to cyclic, rather than, constant hypoxia. Further, existing in vitro models of cyclic hypoxia fail to capture the complex and heterogeneous oxygen dynamics of tumours growing in vivo. Mathematical models can help to overcome current experimental limitations and, in so doing, offer new insights into the biology of tumour cyclic hypoxia by predicting cell responses to a wide range of cyclic dynamics. We develop an individual-based model to investigate how cell cycle progression and cell fate determination of cancer cells are altered following exposure to cyclic hypoxia. Our model can simulate standard in vitro experiments, such as clonogenic assays and cell cycle experiments, allowing for efficient screening of cell responses under a wide range of cyclic hypoxia conditions. Simulation results show that the same cell line can exhibit markedly different responses to cyclic hypoxia depending on the dynamics of the oxygen fluctuations. We also use our model to investigate the impact of changes to cell cycle checkpoint activation and damage repair on cell responses to cyclic hypoxia. Our simulations suggest that cyclic hypoxia can promote heterogeneity in cellular damage repair activity within vascular tumours.

Targeting the EGFR and Spindle Assembly Checkpoint Pathways in Oral Cancer: A Plausible Alliance to Enhance Cell Death.

Background/Objectives: Head and neck cancer (HNC) is among the most common cancer types globally, with its incidence expected to increase significantly in the coming years. Oral squamous cell carcinoma (OSCC), the predominant subtype, exhibits significant heterogeneity and resistance to treatment. Current therapies, including surgery, radiation, and chemotherapy, often result in poor outcomes for advanced stages. Cetuximab, an EGFR inhibitor, is widely used but faces limitations. This study explores the combined inhibition of EGFR and mitotic proteins to enhance treatment efficacy. Methods: We analyzed the effects of co-treating OSCC cells with small molecules targeting MPS-1 (BAY1217389), Aurora-B (Barasertib), or KSP (Ispinesib), alongside Cetuximab. The rationale is based on targeting EGFR-mediated survival pathways and the mitotic checkpoint, addressing multiple cell cycle phases and reducing resistance. Results: Our findings indicate that inhibiting MPS-1, Aurora-B, or KSP enhances Cetuximab's therapeutic potential, promoting increased cancer cell death. Additionally, we examined EGFR, MPS-1, Aurora-B, and KSP expression in OSCC patient samples, revealing their clinicopathologic significance. Conclusions: This combinatorial approach suggests a promising strategy to improve treatment outcomes in OSCC.

Synergistic effects of MK-1775 and gemcitabine on cytotoxicity in non-small cell lung cancer

BackgroundNon-small cell lung cancer (NSCLC) remains a leading cause of cancer-related mortality. Chemotherapy is crucial in NSCLC treatment, and targeting Wee1 kinase, a key regulator of the G2/M cell cycle checkpoint, may enhance the efficacy of cytotoxic agents. This study investigates the potential of the Wee1 inhibitor MK-1775 in combination with gemcitabine and pemetrexed to enhance cytotoxicity in NSCLC cell lines. MethodsHuman NSCLC cell lines H1975, HCC827, A549, and H460 were treated with MK-1775 and chemotherapeutic agents, both alone and in combination. Growth inhibitory effects were assessed using the CCK8 assay. Apoptotic markers were evaluated via Western blotting, and cell cycle distribution was analyzed using FACS. In vivo efficacy was assessed using xenograft mouse models with H1975 and H460 cells, monitoring tumor growth and treatment toxicity. ResultsMK-1775 combined with gemcitabine or pemetrexed significantly decreased cell survival rates and IC50 values in A549 and HCC827 cell lines. Increased levels of phosphorylated cdc2, γ-H2AX, and PARP indicated enhanced apoptosis. Cell cycle analysis revealed G2/M phase arrest in p53-mutant HCC827 and H1975 cells treated with MK-1775 and gemcitabine. In xenograft models, the combination significantly inhibited tumor growth without significant toxicity. ConclusionsMK-1775 enhances the cytotoxic effects of gemcitabine and pemetrexed in NSCLC cell lines and effectively inhibits tumor growth in vivo. These findings suggest that Wee1 inhibition by MK-1775, combined with chemotherapy, represents a promising therapeutic strategy for NSCLC treatment.

The Effect of Circulating Exosomes Obtained from Young and Old Individuals on the Aging related hTERT and P16 Expression in Hematopoietic Stem Cells

Introduction: Functional reduction of telomeres can induce DNA damage response through cell cycle checkpoints and contribute to the senescence of stem cells. The effect of exosomes on the aging and rejuvenation of hematopoietic stem cells (HSCs) is not well known. Therefore, the present study is designed to examine the impact of plasma exosomes derived from young and old individuals on hTERT and P16 expression involved in the cellular aging process. Methods: Exosomes isolated from four young (Y-Exo) and four old (O-Exo) men were evaluated for CD63 protein expression, morphology, size and zeta potential. HSCs were treated with exosomes, and then, the cell viability and the mRNA expression (hTERT and P16) were evaluated using MTT and qRT-PCR methods, respectively. To measure the hTERT protein level, a western blot technique was performed. Results: The gene expression of hTERT was significantly decreased in HSCs treated with 5 μg/ml (O5-Exo) and 10 μg/ml (O10-Exo) doses of exosomes obtained from elderly individuals compared to the cells treated with young exosomes and the untreated HSCs (p < 0.05). In addition, there was a profound elevation of hTERT protein in the HSCs treated with both doses of young exosomes in comparison with the cells treated with both doses of old exosomes (p < 0.05). Moreover, P16 expression was markedly upregulated in the O5-Exo and O10-Exo groups compared to the untreated group (p < 0.05). Conclusion: Our findings reinforce the concept that depending on the age of individuals, circulating exosomes may acquire properties that affect the pathways involved in the aging process in HSCs.