Cell Proliferation Arrest Research Articles

The IP3R inhibitor desmethylxestospongin B reduces tumor cell migration, invasion and metastasis by impairing lysosome acidification and β1-integrin recycling.

Cancer is the second leading cause of death worldwide. >90 % of cancer-related deaths are due to metastasis, a process that depends on the ability of cancer cells to leave the primary tumor, migrate, and colonize different tissues. Inositol 1,4,5-trisphosphate receptor (IP3R)-mediated Ca2+ signaling plays an essential role in maintaining the homeostasis of cancer cells and the sustained proliferation. Desmethylxestospongin B (dmXeB) is a specific inhibitor of the IP3R that selectively arrests cell proliferation and promotes cancer cell death at high concentrations. However, whether migration, invasion and metastasis can be affected by this drug is unknown. Here, by using the highly metastatic triple negative breast cancer (TNBC) cell line MDA-MB-231, we demonstrate that a prolonged inhibition of IP3R-mediated Ca2+ signals with dmXeB significantly reduces cell migration and invasion in vitro and metastasis in vivo. We found that this phenomenon was independent of the bioenergetic control of IP3R over the mitochondria and AMPK activation. Furthermore, employing a tandem LC3-GFP-mcherry assay, we found that prolonged inhibition of IP3R with dmXeB leads to diminished autophagic flux. This reduction can be attributed to impaired lysosomal acidification, as evidenced by assessments using DQ-BSA and pHrodo. Since cell migration requires appropriate assembly and disassembly of focal adhesions, along with the internalization and recycling of integrins via autophagy, we explored the dependency of integrin recycling from autophagosomes, finding that IP3R inhibition with dmXeB impaired the recycling of β1-integrins, which accumulated within autophagosomes. Our findings reveal an unexpected effect of IP3R inhibition with dmXeB in cancer cells that could represent a novel therapeutic strategy for the treatment of cancer metastasis.

Mitochondrial dysfunction matures Ras-induced early senescence to full senescence with a proinflammatory senescence-associated secretory phenotype in the fish cell line, EPC

Fish cell lines differ from most mammalian diploid cell lines by the fact that cellular senescence is not readily induced. Previously, we demonstrated that the absence of the p16 gene in the fish genome prevents cells from reaching full senescence even when Ras is activated. Drosophila also lacks p16; however, early senescence triggered by Ras activation progresses to full senescence and is accompanied by a proinflammatory senescence-associated secretory phenotype (SASP), due to mitochondrial deficiency. It is unclear whether mitochondrial deficiency can also induce the maturation of Ras-induced early senescence (RIS) to full senescence along with a proinflammatory SASP in fish cell lines. Here, we investigated whether mitochondrial dysfunction induced by carbonyl cyanide 3-chlorophenylhydrazone (CCCP) in concert with activated Ras results in full senescence and whether this is accompanied by a proinflammatory SASPs in the EPC fish cell line. We found that although EPC cells with mitochondrial dysfunction exhibited a proinflammatory SASP, this did not result in permanent cell proliferation arrest or the upregulation of endogenous Ras expression. These findings suggest that other factors must act in concert with mitochondrial dysfunction to induce full senescence. The proliferation of EPC cells overexpressing a constitutively active mutant of H-Ras (H-RasV12) was markedly reduced, irrespective of CCCP treatment. These findings suggest that there are similarities between the cellular senescence observed in fish and Drosophila cells lacking the p16 gene. However, it should be noted that fish cells differ from Drosophila cells in that mitochondrial dysfunction alone can induce proinflammatory SASP factors.

8796 Increased Sertoli Cell Proliferation in FSTL3 Deleted Mouse Testis

Abstract Disclosure: R. Ballesteros: None. A. Mukherjee: None. Activin, a TGFβ ligand, plays key roles in Sertoli cell proliferation. Follistatin like 3 (FSTL3) is a glycoprotein inhibitor of activin expressed strongly in the testis. We have shown that FSTL3 deletion (FSTL3 KO) in mice increases testicular size, likely caused by increased spermatogenesis supported by the increased Sertoli cell numbers seen in FSTL3 KO mouse testes. It is not clear, however, whether there is increased proliferation of Sertoli cells postnatally. We, therefore, investigated Sertoli cell proliferation, and molecular pathways that might be activated upon FSTL3 deletion that lead to increased Sertoli cell proliferation in mice. Paired testes weight comparison indicates that there is significant increase in testicular mass in FSTL3 KO between 28d and 56d coinciding with the onset of continued spermatogenesis. Immunofluorescence studies using PCNA as marker for proliferation and SOX9 to identify Sertoli cells, however, found no significant differences between proliferation of Sertoli cells in WT and FSTL3 KO. BrdU injection of mice followed by immunofluorescence labelling of proliferating Sertoli cells also showed no difference between the two genotypes by immunofluorescence. We then proceeded to assess whether there is an alteration of differentiation in FSTL3 KO testes to test the possibility that instead of proliferation there is an increased differentiation of a pre-Sertoli like cell in FSTL3 KO mice using WT1 and SOX9 as markers for early or late Sertoli cells. This experiment revealed that there was no difference between the ratio of WT1 and SOX9 expression in the two genotypes. Flow cytometric analyses using testicular dispersates from mice using Sox9 and Ki67 antibodies to identify proliferating Sertoli cells, however, revealed an approximately two-fold increase in proliferating Sertoli cells in FSTL3 KO compared to WT at 7d. At 56d there were very few proliferating Sertoli cells in either genotype and there was no difference in this number in FSTL3 deleted mice compared to WT. mRNA sequence analysis showed that approximately 1000 genes are differentially regulated between WT and FSTL3 KO at 3d. Gene ontology and pathway analysis revealed that a constellation of meiosis related genes and activin signalling pathway, among others, are enriched in FSTL3 KO testis at this stage. Data presented here demonstrates that FSTL3 deletion induces activin receptor signalling pathway, genes crucial for meiosis and therefore the spermatogenic process, and Sertoli cell proliferation. This opens the possibility that the early arrest of Sertoli cell proliferation seen in mammals including mice and humans might be circumvented by inactivating FSTL3. This could then lead to a therapeutic angle in male infertility that are based on paucity of Sertoli cells. It will be important to address why FSTL3 deletion induces Sertoli cell proliferation only postnatally but not post pubertally. Presentation: 6/1/2024

8796 Increased Sertoli Cell Proliferation in FSTL3 Deleted Mouse Testis

Abstract Disclosure: R. Ballesteros: None. A. Mukherjee: None. Activin, a TGFβ ligand, plays key roles in Sertoli cell proliferation. Follistatin like 3 (FSTL3) is a glycoprotein inhibitor of activin expressed strongly in the testis. We have shown that FSTL3 deletion (FSTL3 KO) in mice increases testicular size, likely caused by increased spermatogenesis supported by the increased Sertoli cell numbers seen in FSTL3 KO mouse testes. It is not clear, however, whether there is increased proliferation of Sertoli cells postnatally. We, therefore, investigated Sertoli cell proliferation, and molecular pathways that might be activated upon FSTL3 deletion that lead to increased Sertoli cell proliferation in mice. Paired testes weight comparison indicates that there is significant increase in testicular mass in FSTL3 KO between 28d and 56d coinciding with the onset of continued spermatogenesis. Immunofluorescence studies using PCNA as marker for proliferation and SOX9 to identify Sertoli cells, however, found no significant differences between proliferation of Sertoli cells in WT and FSTL3 KO. BrdU injection of mice followed by immunofluorescence labelling of proliferating Sertoli cells also showed no difference between the two genotypes by immunofluorescence. We then proceeded to assess whether there is an alteration of differentiation in FSTL3 KO testes to test the possibility that instead of proliferation there is an increased differentiation of a pre-Sertoli like cell in FSTL3 KO mice using WT1 and SOX9 as markers for early or late Sertoli cells. This experiment revealed that there was no difference between the ratio of WT1 and SOX9 expression in the two genotypes. Flow cytometric analyses using testicular dispersates from mice using Sox9 and Ki67 antibodies to identify proliferating Sertoli cells, however, revealed an approximately two-fold increase in proliferating Sertoli cells in FSTL3 KO compared to WT at 7d. At 56d there were very few proliferating Sertoli cells in either genotype and there was no difference in this number in FSTL3 deleted mice compared to WT. mRNA sequence analysis showed that approximately 1000 genes are differentially regulated between WT and FSTL3 KO at 3d. Gene ontology and pathway analysis revealed that a constellation of meiosis related genes and activin signalling pathway, among others, are enriched in FSTL3 KO testis at this stage. Data presented here demonstrates that FSTL3 deletion induces activin receptor signalling pathway, genes crucial for meiosis and therefore the spermatogenic process, and Sertoli cell proliferation. This opens the possibility that the early arrest of Sertoli cell proliferation seen in mammals including mice and humans might be circumvented by inactivating FSTL3. This could then lead to a therapeutic angle in male infertility that are based on paucity of Sertoli cells. It will be important to address why FSTL3 deletion induces Sertoli cell proliferation only postnatally but not post pubertally. Presentation: 6/1/2024

Potent drug candidature of copper-coordinated metallodrug: Experimental study, spectroscopic insights, anticancer activity, apoptosis analysis, cell cycle, theoretical calculations, and molecular docking studies

The biological properties of the thiocarbohydrazone, pyrazole, and copper ions are well-known, thus copper complexes incorporated with pyrazole-thiocarbohydrazone hybrid ligands have potential medical applications. In this study, copper complex [Cu(PMT)2(Cl)2] derived from pyrazole-thiocarbohydrazone hybrid chelator (PMT) was successfully synthesized. With the help of several fundamental techniques, including elemental and thermal studies, molar conductivity, and magnetic moment measurements, the structure and coordination behavior of the PMT chelator and its Cu(PMT) nanocomplex were examined. In addition, records of ESR, FT-IR, and UV–Vis spectroscopy were obtained. The powder X-ray diffraction data has identified significant information about the crystalline forms of the Cu(PMT) chelate. The findings demonstrated that producing octahedral, mono-species of chelate and chelation occurs through the N, and S donor sites of neutral chelator. The cytotoxicity assessment of the PMT and its Cu(PMT) chelate was further evaluated against human ovary cancer cells (SKOV3), human breast cancer cells (MCF-7), and human colon cancer cells (HCT116) by using SRB assay. The Cu(PMT) chelate displayed promising results regarding standard doxorubicin. Furthermore, the apoptosis analysis of the Cu(PMT) chelate strongly induced the late-apoptotic cell population against the tested cancer cells. Also, the cell-cycle distribution of the Cu(PMT) complex arrests cell proliferation at the G1, S, and G2 phases. PMT and its Cu(PMT) were also studied using computational simulations and the DFT approach. Different chemical quantum parameters were determined from the optimized structure. The interaction between copper chelate and the CDK8 kinase active site was examined using docking studies.

In Vivo Chemical Screening in Zebrafish Embryos Identified FDA-Approved Drugs That Induce Differentiation of Acute Myeloid Leukemia Cells.

Acute myeloid leukemia (AML) is characterized by the abnormal proliferation and differentiation arrest of myeloid progenitor cells. The clinical treatment of AML remains challenging. Promoting AML cell differentiation is a valid strategy, but effective differentiation drugs are lacking for most types of AML. In this study, we generated Tg(drl:hoxa9) zebrafish, in which hoxa9 overexpression was driven in hematopoietic cells and myeloid differentiation arrest was exhibited. Using Tg(drl:hoxa9) embryos, we performed chemical screening and identified four FDA-approved drugs, ethacrynic acid, khellin, oxcarbazepine, and alendronate, that efficiently restored myeloid differentiation. The four drugs also induced AML cell differentiation, with ethacrynic acid being the most effective. By an RNA-seq analysis, we found that during differentiation, ethacrynic acid activated the IL-17 and MAPK signaling pathways, which are known to promote granulopoiesis. Furthermore, we found that ethacrynic acid enhanced all-trans retinoic acid (ATRA)-induced differentiation, and both types of signaling converged on the IL-17/MAPK pathways. Inhibiting the IL-17/MAPK pathways impaired ethacrynic acid and ATRA-induced differentiation. In addition, we showed that ethacrynic acid is less toxic to embryogenesis and less disruptive to normal hematopoiesis than ATRA. Thus, the combination of ethacrynic acid and ATRA may have broader clinical applications. In conclusion, through zebrafish-aided screening, our study identified four drugs that can be repurposed to induce AML differentiation, thus providing new agents for AML therapy.

Cuproptosis-related gene <i>ATOX1</i> promotes MAPK signaling and diffuse large B-cell lymphoma proliferation via modulating copper transport

Diffuse Large B-cell lymphoma (DLBCL) is a common subtype of non-Hodgkin lymphoma, highlighting the importance of studying susceptibility genes to develop personalized treatment strategies. While cuproptosis, caused by high levels of copper ions induced by ionophores, has been shown to affect cancer survival, its specific role in lymphoma is not yet clear. To investigate the involvement of upregulation-related genes in DLBCL, we employed bioinformatics techniques. Specifically, we analyzed the differentially expressed genes (DEGs) in the GSE25638 dataset using Weighted Gene Co-expression Network Analysis (WGCNA) and performed functional enrichment analysis. By building a Protein-Protein Interaction (PPI) network, candidate genes were identified. Gene Set Enrichment Analysis (GSEA) and Receiver Operating Characteristic (ROC) curve analysis were used to confirm the clinical diagnostic use of these genes. The effects of Antioxidant 1 (ATOX1) knockdown, CuCl2, and DCAC50 treatments on DLBCL cells and the activation of the Mitogen-Activated Protein Kinase (MAPK) pathway were investigated by conducting in vitro experiments. Bioinformatics and in vitro experiments confirmed elevated expression of ATOX1 in DLBCL cells and tumor samples. ATOX1 knockdown led to decreased cell proliferation and G2 cell cycle arrest in vitro. Additionally, Phosphorylated Extracellular Signal-Regulated Kinases 1 and 2 (P-ERK1/2) protein levels within the MAPK pathway were reduced as a result of ATOX1 knockdown, but these levels were recovered by CuCl2. Treatment with DCAC50 showed a dose-dependent antiproliferative effect in DLBCL cells, which was strengthened by ATOX1 knockdown. Our study demonstrated that ATOX1 may be important in DLBCL via controlling the MAPK pathway through copper transport, providing new insights into potential therapeutic strategies for DLBCL.

Targeting specific DNA G-quadruplexes with CRISPR-guided G-quadruplex-binding proteins and ligands.

Despite the demonstrated importance of DNA G-quadruplexes (G4s) in health and disease, technologies to readily manipulate specific G4 folding for functional analysis and therapeutic purposes are lacking. Here we employ G4-stabilizing protein/ligand in conjunction with CRISPR to selectively facilitate single or multiple targeted G4 folding within specific genomic loci. We demonstrate that fusion of nucleolin with a catalytically inactive Cas9 can specifically stabilize G4s in the promoter of oncogene MYC and muscle-associated gene Itga7 as well as telomere G4s, leading to cell proliferation arrest, inhibition of myoblast differentiation and cell senescence, respectively. Furthermore, CRISPR can confer intra-G4 selectivity to G4-binding compounds pyridodicarboxamide and pyridostatin. Compared with traditional G4 ligands, CRISPR-guided biotin-conjugated pyridodicarboxamide enables a more precise investigation into the biological functionality of de novo G4s. Our study provides insights that will enhance understanding of G4 functions and therapeutic interventions.

MRE11 and TREX1 control senescence by coordinating replication stress and interferon signaling

Oncogene-induced senescence (OIS) arrests cell proliferation in response to replication stress (RS) induced by oncogenes. OIS depends on the DNA damage response (DDR), but also on the cGAS-STING pathway, which detects cytosolic DNA and induces type I interferons (IFNs). Whether and how RS and IFN responses cooperate to promote OIS remains unknown. Here, we show that the induction of OIS by the H-RASV12 oncogene in immortalized human fibroblasts depends on the MRE11 nuclease. Indeed, treatment with the MRE11 inhibitor Mirin prevented RS, micronuclei formation and IFN response induced by RASV12. Overexpression of the cytosolic nuclease TREX1 also prevented OIS. Conversely, overexpression of a dominant negative mutant of TREX1 or treatment with IFN-β was sufficient to induce RS and DNA damage, independent of RASV12 induction. These data suggest that the IFN response acts as a positive feedback loop to amplify DDR in OIS through a process regulated by MRE11 and TREX1.

Avellanin A Has an Antiproliferative Effect on TP-Induced RWPE-1 Cells via the PI3K-Akt Signalling Pathway.

Cyclic pentapeptide compounds have garnered much attention as a drug discovery resource. This study focused on the characterization and anti-benign prostatic hyperplasia (BPH) properties of avellanin A from Aspergillus fumigatus fungus in marine sediment samples collected in the Beibu Gulf of Guangxi Province in China. The antiproliferative effect and molecular mechanism of avellanin A were explored in testosterone propionate (TP)-induced RWPE-1 cells. The transcriptome results showed that avellanin A significantly blocked the ECM-receptor interaction and suppressed the downstream PI3K-Akt signalling pathway. Molecular docking revealed that avellanin A has a good affinity for the cathepsin L protein, which is involved in the terminal degradation of extracellular matrix components. Subsequently, qRT-PCR analysis revealed that the expression of the genes COL1A1, COL1A2, COL5A2, COL6A3, MMP2, MMP9, ITGA2, and ITGB3 was significantly downregulated after avellanin A intervention. The Western blot results also confirmed that it not only reduced ITGB3 and FAK/p-FAK protein expression but also inhibited PI3K/p-PI3K and Akt/p-Akt protein expression in the PI3K-Akt signalling pathway. Furthermore, avellanin A downregulated Cyclin D1 protein expression and upregulated Bax, p21WAF1/Cip1, and p53 proapoptotic protein expression in TP-induced RWPE-1 cells, leading to cell cycle arrest and inhibition of cell proliferation. The results of this study support the use of avellanin A as a potential new drug for the treatment of BPH.

Mechanical load regulates the proliferation of multiple cell types in the heart

Abstract Funding Acknowledgements None. Introduction The adult mammalian heart has a poor regenerative and angiogenic potential. At the same time, both primary cardiac tumors and cardiac metastases are extremely rare. This suggests that shared mechanisms may halt the proliferation of cardiac (both cardiomyocyte and endothelial) and cancer cells. Among the mechanisms that have been claimed to be responsible for the loss of proliferative potential of cardiomyocytes early after birth is a sudden increase in mechanical load. Purpose Here, we investigate whether alterations in mechanical load affect the proliferation of multiple cell types in the heart. Methods Adult heart unloading in vivo was achieved using a mouse model of heterotopic heart transplantation, followed by EdU injection to label proliferating cells. Engineered heart tissues (EHTs) were generated using neonatal cardiomyocytes and fibroblasts, with a modified protocol allowing to finely tune mechanical load. Primary cardiac endothelial cells and multiple types of cancer cells (lung, melanoma and colon cancer) along with adult cardiac endothelial cells were included in EHTs. Results In line with our hypothesis, unloaded, heterotransplanted hearts showed a significant number of proliferating cardiomyocytes and endothelial cells, which were almost absent in native hearts. While cancer cells did not grow in native hearts, they massively proliferated in unloaded hearts. Consistent with in vivo results, mechanical unloading in EHTs significantly increased the percentage of EdU-positive cardiomyocytes, endothelial and cancer cells. In contrast, increasing afterload reduced cell proliferation in all cell types. Mechanistically, we identified Nesprin2 as an essential factor in sensing mechanical load and translating it into a cell proliferation arrest. Conclusions Overall, these data indicate that variations in mechanical load have a dramatic effect on the proliferation of multiple cell types within the heart tissue, including cardiomyocytes, endothelial and cancer cells and that Nesprin2 is required to mediate this effect.Unloading in the heartUnloading in EHT

CircSLC25A16 facilitates the development of non-small-cell lung cancer through the miR-335-5p/CISD2 axis.

Non-small-cell lung cancer (NSCLC) is a common malignancy with high morbidity and mortality. Circular RNAs are widely involved in NSCLC progression. However, the mechanism of circSLC25A16 in NSCLC has not been reported. The expressions of circSLC25A16, microRNA-335-5p (miR-335-5p), and CDGSH iron-sulfur domain-containing protein 2 (CISD2) were monitored by quantitative real-time fluorescence polymerase chain reaction. Western blot was also carried out to measure the protein levels of CISD2, hexokinase 2 (HK2), and lactate dehydrogenase A (LDHA). For functional analysis, cell counting kit-8 assay, 5-ethynyl-2'-deoxyuridine, flow cytometry, transwell, and wound healing assays were utilized to examine cell proliferation, apoptosis, and migration. Glucose uptake and lactate production were detected using commercial kits. The relationship between miR-335-5p and circSLC25A16 or CISD2 was verified by dual-luciferase reporter and RNA immunoprecipitation assays. Furthermore, tumor xenograft was established to explore the function of circSLC25A16 in vivo. CircSLC25A16 and CISD2 were overexpressed in NSCLC, but miR-335-5p was downregulated. CircSLC25A16 acted as a miR-335-5p sponge, and silencing of circSLC25A16 arrested cell proliferation, migration, and glycolysis, and promoted apoptosis, but these impacts were resumed by miR-335-5p inhibition. CISD2 was a miR-335-5p target, and overexpression of CISD2 abolished the suppressive function of miR-335-5p mimic on the malignant behavior of NSCLC cells. CircSLC25A16 could adsorb miR-335-5p to mediate CISD2 expression. Additionally, silencing circSLC25A16 restrained the growth of NSCLC tumor xenograft in vivo. CircSLC25A16 facilitated NSCLC progression via the miR-335-5p/CISD2 axis, implying that circSLC25A16 may serve as a novel biomarker for NSCLC treatment.

Design, Synthesis, and Evaluation of Novel Cryptotanshinone Derivatives for Activity against Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) can be difficult to treat because of resistance to existing therapeutic agents. Our prior studies revealed the inhibitory effect of the natural product cryptotanshinone (CTS) on the proliferation of TNBC cells; however, its clinical application was prevented due to its low water solubility and activity. This study aimed to synthesize derivatives of CTS with enhanced potency and water solubility. The structure of CTS was modified by adding amino acid side chains, which were derived into phosphonium salts. The derivatives were immersed in phosphate-buffered saline (PBS) to assess their water solubility. The antitumor effects of the derivatives against MDA-MB-231 breast cancer cells were assessed by evaluating their roles in regulating cell proliferation, cell apoptosis, and cell-cycle arrest using cell counting kit-8 (CCK-8), flow cytometry, and calcein-AM/propidium iodide assay, respectively. In this work, a total of 29 derivatives of CTS were synthesized, of which the tricyclohexylphosphine derivatives C4-2 and C5-2 were highly soluble in PBS, with 790- and 450-fold higher than that of CTS, respectively, and at the same time, the antitumor activities of C4-2 and C5-2 were also enhanced, with two- and fourfold higher than that of CTS, respectively. Further studies revealed that the compounds may inhibit the proliferation of MDA-MB-231 by inducing cellular arrest in the G2/M phase. These findings provided preliminary data for the mechanisms of CTS and its derivatives in blocking TNBC and suggested C4-2 and C5-2 as potential agents for the treatment of the disease in the future.

Enhancement of the Tumor Suppression Effect of High-dose Radiation by Low-dose Pre-radiation Through Inhibition of DNA Damage Repair and Increased Pyroptosis.

Radiation therapy has been a critical and effective treatment for cancer. However, not all cells are destroyed by radiation due to the presence of tumor cell radioresistance. In the current study, we investigated the effect of low-dose radiation (LDR) on the tumor suppressive effect of high-dose radiation (HDR) and its mechanism from the perspective of tumor cell death mode and DNA damage repair, aiming to provide a foundation for improving the efficacy of clinical tumor radiotherapy. We found that LDR pre-irradiation strengthened the HDR-inhibited A549 cell proliferation, HDR-induced apoptosis, and G2 phase cell cycle arrest under co-culture conditions. RNA-sequencing showed that differentially expressed genes after irradiation contained pyroptosis-related genes and DNA damage repair related genes. By detecting pyroptosis-related proteins, we found that LDR could enhance HDR-induced pyroptosis. Furthermore, under co-culture conditions, LDR pre-irradiation enhances the HDR-induced DNA damage and further suppresses the DNA damage-repairing process, which eventually leads to cell death. Lastly, we established a tumor-bearing mouse model and further demonstrated that LDR local pre-irradiation could enhance the cancer suppressive effect of HDR. To summarize, our study proved that LDR pre-irradiation enhances the tumor-killing function of HDR when cancer cells and immune cells were coexisting.

Abstract 436: Extracellular glutathione catabolism as an alternative cyst(e)ine source in cancer

Abstract Glutathione (GSH) is the most abundant antioxidant in the human body and plays essential roles in physiology and disease. Unchecked oxidative stress is involved in tumor initiation and progression. Paradoxically, clinical and laboratory data show that ROS-scavenging molecules such as glutathione not only fail to impede tumor growth but, in many cases, accelerate it. Still, preliminary data from our lab show that genetically ablating tumors’ ability to synthesize GSH does not affect their growth. This finding suggests that the favorable influence of glutathione on tumor growth may arise from external sources. Yet, the mechanism cancer cells employ to take advantage of extracellular glutathione in this context is unknown. Here, we show that γ-glutamyl-transpeptidase 1 (GGT1), an enzyme that localizes on the outer side of the cell’s membrane, can break down extracellular GSH, yielding glutamate and the dipeptide cysteinylglycine. Cysteinylglycine can be further metabolized, generating cysteine and glycine to the cells. We found that the addition of exogenous GSH, as well as cysteinylglycine, can mitigate cell death, proliferation arrest, and oxidative stress caused by cystine depletion. The overexpression of human GGT1 in cancer cells significantly reduces the amount of glutathione needed to rescue cell fitness. Accordingly, pharmacologic inhibition of GGT1 activity prevented GSH's ability to rescue cell proliferation. Moreover, an unbiased pharmacological screening revealed that GGT1-mediated cysteine acquisition renders cancer cells resistant to inhibitors of cystine uptake and utilization, supporting the role of GGT1 as a source of cyst(e)ine. Our findings reveal that cancer cells can access cysteine, a vital yet scarce amino acid, through GGT1's ability to break down glutathione, which is present in remarkably high concentrations within the tumor microenvironment. Although the downstream proteins involved in the transport and utilization of GSH breakdown products are yet to be identified, we anticipate this pathway has the potential to uncover novel therapeutic avenues for cancer treatment by targeting alternative pathways of nutrient acquisition that are potentially implicated in cancer progression and therapy resistance. Citation Format: Fabio Hecht, Marco Zocchi, Emily Tuttle, Gloria Asantewaa, TashJaé Scales, Fatemeh Alimohammadi, Nathan Ward, Gina DeNicola, Isaac Harris. Extracellular glutathione catabolism as an alternative cyst(e)ine source in cancer [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 436.

The pharmacological properties of Gypsophila eriocalyx: The endemic medicinal plant of northern central Turkey

The aim of this study is to evaluate and compare the biological properties of different extracts (methanol, ethanol, and water) obtained from Gypsophila eriocalyx (G. eriocalyx), a medicinal plant traditionally used in Turkey. The components of different extracts were defined using the GC–MS method. The effects of G. eriocalyx extracts on cell proliferation, apoptosis, and cell cycle arrest in MDA-MB-231 breast cancer as well as in vitro antioxidant, enzyme inhibition, and antimicrobial activities were investigated. In accordance with the results obtained, although ethanol and methanol extracts of G. eriocalyx show higher antioxidant activity than G. eriocalyx water extract, enzyme inhibition activities of the extracts were not found to be significant compared to the reference drug. The methanol and ethanol extract of G. eriocalyx exhibited moderate antimicrobial activity against Staphylococcus aureus and methanol extract showed significant antimicrobial activity against Bacillus cereus. In addition, both extracts significantly inhibited cell viability in a dose-dependent manner in breast cancer cells. The cell growth inhibition by methanol and ethanol extracts induced S phase cell-cycle arrest and apoptosis in MDA-MB-231 cells. Lastly, in order to compare the activities of the chemicals found in Gypsophila eriocalyx plant extract, their activities against various proteins that are breast cancer protein (PDB ID:1A52 and 1JNX), antioxidant protein (PDB ID: 1HD2), AChE enzyme protein (PDB ID: 4M0E), BChE enzyme protein (PDB ID: 5NN0), and Escherichia coli protein (PDB ID: 4PRV)were compared. Then, ADME/T analysis calculations were made to examine the effects of molecules with high activity on human metabolism. Eventually, G. eriocalyx is thought to be a potent therapeutic herb that can be considered as an alternative and functional therapy for the management of diseases of a progressive nature related to oxidative damage such as infection, diabetes, cancer, and Alzheimer's disease.

Abstract 7258: Combinatorial effects of viral oncolysis and miRNA modulation as a novel therapeutic of pancreatic ductal adenocarcinoma

Abstract Pancreatic cancer is a devastating illness that affects numerous individuals each year. Unfortunately, pancreatic ductal adenocarcinoma (PDAC) is an aggressive form of this disease that accounts for a disproportionate number of cancer-related deaths. Despite representing only 3.3% of all cancer cases in the United States, pancreatic cancer is responsible for a staggering 8.3% of cancer-related fatalities. In 2023, 64,050 patients were diagnosed with PDAC alone. Current treatment options, which are limited to surgery, radiation, and chemotherapy, have failed to improve clinical outcomes. Recent research has revealed miRNA (miR) as a contributor to the suppression and progression of various cancers, including PDAC. Specifically, dysregulation of miR-7 has been associated with PDAC. Downregulation of miR-7 is linked to more aggressive cases of the disease. Another potential therapeutic approach to treating cancer is the use of oncolytic viruses (OV). These viruses can replicate in cancerous cells while leaving healthy cells unharmed, making them an attractive treatment option. In this study, we utilized exosomes isolated from human Umbilical Cord stem cells (hUCs) enriched with miR-7 and combined with OHSV to examine their effect on established PDAC cell lines. We utilized cell viability assays, microscopy, and western blot analysis to evaluate the impact of the combinatorial approach on the underlying molecular mechanisms. Our findings suggest that the successful transfer of miR cargo and treatment with oHSV into the target PDAC cells arrested cell proliferation by targeting apoptotic pathways. Citation Format: Monique Kanitz Ruschel, Isaiah Davis, Hannah Taylor Mills, Karthik Gourishetti, Deepak Bhere. Combinatorial effects of viral oncolysis and miRNA modulation as a novel therapeutic of pancreatic ductal adenocarcinoma [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 7258.

Abstract 3308: A selective FGFR1/2 degrader overcomes endocrine resistance in ER+/FGFR1-amplified andFGFR1/2-mutant breast cancer

Abstract FGFR1 amplification and FGFR1/2 activating mutations are associated with resistance to antiestrogens in the estrogen receptor-positive (ER+) breast cancer. In this study, we investigated selective degradation of FGFR1/2 using the proteolysis-targeted chimera (PROTAC) DGY-09-192 as a novel therapeutic strategy to overcome resistance to antiestrogens in ER+ breast cancers harboring FGFR1-amplification or FGFR1/2 activating mutations. Treatment of ER+/FGFR1-amplified CAMA1 and MDA-MB-134 breast cancer cells with DGY-09-192 degraded FGFR1 and suppressed phosphorylation of FGFR1 and its downstream targets FRS2, AKT, and ERK1/2. DGY-09-192-mediated FGFR1 degradation were rescued by a proteasome inhibitor, MG132, suggesting that the antitumor activity of DGY-09-192 depends on proteasome-mediated degradation. Growth of CAMA1 and MDA-MB-134 cells were modestly inhibited by single-agent DGY-09-192 or the ER degrader fulvestrant, but the combination completely arrested cell proliferation. Treatment of female NSG mice bearing established ER+/FGFR1-amplified patient-derived xenografts (PDXs) with single-agent DGY-09-192 (40 mg/kg/day, i.p.) or fulvestrant (5 mg/week, s.c.) delayed tumor growth, respectively. However, treatment with DGY-09-192 + fulvestrant induced tumor regression in all mice (n=7), suggesting that a FGFR1 degrader plus an antiestrogen can serve as an effective therapeutic combination for ER+/FGFR1-amplified breast cancer. Next, we examined whether ER+ breast cancer cells harboring FGFR1/2 hotspot mutations are sensitive to DGY-09-192. Ectopic expression of FGFR1N546K, the most common FGFR1 mutation in breast cancer, activated FGFR1 signaling and induced resistance to fulvestrant compared to MCF7 cells transduced with wild-type FGFR1. EFM-19 cells harboring FGFR2K659E exhibited resistance to fulvestrant in vitro. Treatment of both cell lines with DGY-09-192 degraded the mutant FGFR1N546K and FGFR2K659E, respectively, blocked phosphorylation of the FGFR downstream targets, and markedly inhibited cell proliferation. These results suggest that PROTAC-mediated degradation of FGFR1/2 effectively blocks the growth of ER+, FGFR1/2-mutant breast cancers resistant to antiestrogens. Conclusions: DGY-09-192 induced FGFR1/2 degradation and blocks FGFR downstream signaling in ER+/FGFR1-amplified and FGFR1/2-mutant breast cancer cells. The combination of DGY-09-192 and fulvestrant exhibited superior antitumor effects relative to each monotherapy alone in vitro and/or in vivo. Therefore, PROTAC-mediated FGFR1/2 degradation represents a promising therapeutic strategy for ER+ breast cancers harboring FGFR1-amplification or FGFR1/2 activating mutations. Citation Format: Yasuaki Uemoto, Chang-Ching Lin, Bingnan Wang, Dan Ye, Emmanuel Bikorimana, Alberto Servetto, Luigi Formisano, Fabiana Napolitano, Rosario Chica Parrado, Saurabh Mendiratta, Chuo Chen, Ariella B. Hanker, Carlos L. Arteaga. A selective FGFR1/2 degrader overcomes endocrine resistance in ER+/FGFR1-amplified andFGFR1/2-mutant breast cancer [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 3308.

AURKB promotes bladder cancer progression by deregulating the p53 DNA damage response pathway via MAD2L2

BackgroundBladder cancer (BC) is the most common urinary tract malignancy. Aurora kinase B (AURKB), a component of the chromosomal passenger protein complex, affects chromosomal segregation during cell division. Mitotic arrest-deficient 2-like protein 2 (MAD2L2) interacts with various proteins and contributes to genomic integrity. Both AURKB and MAD2L2 are overexpressed in various human cancers and have synergistic oncogenic effects; therefore, they are regarded as emerging therapeutic targets for cancer. However, the relationship between these factors and the mechanisms underlying their oncogenic activity in BC remains largely unknown. The present study aimed to explore the interactions between AURKB and MAD2L2 and how they affect BC progression via the DNA damage response (DDR) pathway.MethodsBioinformatics was used to analyze the expression, prognostic value, and pro-tumoral function of AURKB in patients with BC. CCK-8 assay, colony-forming assay, flow cytometry, SA-β-gal staining, wound healing assay, and transwell chamber experiments were performed to test the viability, cell cycle progression, senescence, and migration and invasion abilities of BC cells in vitro. A nude mouse xenograft assay was performed to test the tumorigenesis ability of BC cells in vivo. The expression and interaction of proteins and the occurrence of the senescence-associated secretory phenotype were detected using western blot analysis, co-immunoprecipitation assay, and RT-qPCR.ResultsAURKB was highly expressed and associated with prognosis in patients with BC. AURKB expression was positively correlated with MAD2L2 expression. We confirmed that AURKB interacts with, and modulates the expression of, MAD2L2 in BC cells. AURKB knockdown suppressed the proliferation, migration, and invasion abilities of, and cell cycle progression in, BC cells, inducing senescence in these cells. The effects of AURKB knockdown were rescued by MAD2L2 overexpression in vitro and in vivo. The effects of MAD2L2 knockdown were similar to those of AURKB knockdown. Furthermore, p53 ablation rescued the MAD2L2 knockdown-induced suppression of BC cell proliferation and cell cycle arrest and senescence in BC cells.ConclusionsAURKB activates MAD2L2 expression to downregulate the p53 DDR pathway, thereby promoting BC progression. Thus, AURKB may serve as a potential molecular marker and a novel anticancer therapeutic target for BC.

Inhibition of endogenous hydrogen sulfide production reduces activation of hepatic stellate cells via the induction of cellular senescence

ABSTRACT In chronic liver injury, quiescent hepatic stellate cells (HSCs) transdifferentiate into activated myofibroblast-like cells and produce large amounts of extracellular matrix components, e.g. collagen type 1. Cellular senescence is characterized by irreversible cell-cycle arrest, arrested cell proliferation and the acquisition of the senescence-associated secretory phenotype (SASP) and reversal of HSCs activation. Previous studies reported that H2S prevents induction of senescence via its antioxidant activity. We hypothesized that inhibition of endogenous H2S production induces cellular senescence and reduces activation of HSCs. Rat HSCs were isolated and culture-activated for 7 days. After activation, HSCs treated with H2S slow-releasing donor GYY4137 and/or DL-propargylglycine (DL-PAG), an inhibitor of the H2S-producing enzyme cystathionine γ-lyase (CTH), as well as the PI3K inhibitor LY294002. In our result, CTH expression was significantly increased in fully activated HSCs compared to quiescent HSCs and was also observed in activated stellate cells in a in vivo model of cirrhosis. Inhibition of CTH reduced proliferation and expression of fibrotic markers Col1a1 and Acta2 in HSCs. Concomitantly, DL-PAG increased the cell-cycle arrest markers Cdkn1a (p21), p53 and the SASP marker Il6. Additionally, the number of β-galactosidase positive senescent HSCs was increased. GYY4137 partially restored the proliferation of senescent HSCs and attenuated the DL-PAG-induced senescent phenotype. Inhibition of PI3K partially reversed the senescence phenotype of HSCs induced by DL-PAG. Inhibition of endogenous H2S production reduces HSCs activation via induction of cellular senescence in a PI3K-Akt dependent manner. Our results show that cell-specific inhibition of H2S could be a novel target for anti-fibrotic therapy via induced cell senescence.