Transcription Factor NFE2L1 Decreases in Glomerulonephropathies after Podocyte Damage

Podocyte cellular injury and detachment from glomerular capillaries constitute a critical factor contributing to kidney disease. Notably, transcription factors are instrumental in maintaining podocyte differentiation and homeostasis. This study explores the hitherto uninvestigated expression of Nuclear Factor Erythroid 2-related Factor 1 (NFE2L1) in podocytes. We evaluated the podocyte expression of NFE2L1, Nuclear Factor Erythroid 2-related Factor 2 (NFE2L2), and NAD(P)H:quinone Oxidoreductase (NQO1) in 127 human glomerular disease biopsies using multiplexed immunofluorescence and image analysis. We found that both NFE2L1 and NQO1 expressions were significantly diminished across all observed renal diseases. Furthermore, we exposed human immortalized podocytes and ex vivo kidney slices to Puromycin Aminonucleoside (PAN) and characterized the NFE2L1 protein isoform expression. PAN treatment led to a reduction in the nuclear expression of NFE2L1 in ex vivo kidney slices and podocytes.

Abstract 277: NUC-7738 promotes alternative polyadenylation site usage and reduces glutaminase GAC isoform

Background: Metabolic dysregulation, a hallmark of cancer, allows tumor cells to sustain high rates of growth and proliferation in unfavorable conditions, including hypoxia. Many cancers, including clear cell renal cell carcinoma (ccRCC), demonstrate the Warburg effect with high rates of glycolysis and some are dependent on glutamine. These cancers express high levels of glutaminase (GLS), the enzyme responsible for conversion of glutamine to glutamate. GLS exists as two distinct isoforms, GAC and KGA, which are generated by alternative polyadenylation. The presence of GAC favors more metabolically active cell growth, and the GAC:KGA ratio negatively correlates with survival in ccRCC. Selectively inhibiting the GAC isoform may be a target for therapy. NUC-7738, a ProTide transformation of 3'-deoxyadenosine (3’-dA), has shown encouraging efficacy signals in several solid tumor types in a Phase ½ clinical study (NuTide:701 NCT03829254). It generates 3’-dATP which profoundly affects transcription by altering polyadenylation and has been shown to alter expression of mitochondrial electron transport chain genes. The aim of this study was to investigate the impact of NUC-7738 on GLS alternative polyadenylation and the ratio of GAC:KGA isoforms.

Material and Methods: ccRCC (Caki-1 [VHL mutant];786-O [wildtype]) and pancreatic (PANC1; MIAPACA) cancer cell lines were treated with NUC-7738 at IC50 doses in hypoxic and normoxic conditions. NUC-7738 and 3’-dATP were measured by LC-MS. mRNA levels of glutaminase isoforms were determined by RT-qPCR using primers targeting exon 14-15 junction for GAC and exon 16-18 junction for KGA. GAC and KGA protein expression determined by JESS Western analysis.

Results: NUC-7738 was converted into 3’-dATP within 6 hours of treatment with an average concentration of 8 pmol/106 cells, which was maintained for ~24 hours and decreased by 50% by 48 hours. The levels are comparable to those measured in PBMCs from patients treated with NUC-7738. In ccRCC cells (VHL wildtype and mutant), NUC-7738 reduced transcript expression of GAC isoform, with no change in KGA, indicating a change in polyadenylation site usage. This was reflected in altered protein levels, with decreased GAC in ccRCC and pancreatic cell lines in hypoxic and normoxic conditions after NUC-7738 treatment.

Conclusion: NUC-7738 generates sustained levels of 3’-dATP in cells, which is associated with alternative polyadenylation site usage changes. In a variety of cell types, mRNA and protein levels of the more metabolically active GAC isoform were reduced, with an increase in the relative amount of KGA isoform. Increased glutamate production and GAC:KGA ratio are key for survival of some tumors. As alternative polyadenylation is implicated in the control of expression of many genes in cancer, the ability to influence it may lead to new strategies for developing anti-cancer treatments interfering with cellular metabolism.

Citation Format: Mustafa Elshani, Ying Zhang, Tia Hawkins, Mary Kudsy, In Hwa Um, Greice Zickuhr, Alison L. Dickson, David J. Harrison. NUC-7738 promotes alternative polyadenylation site usage and reduces glutaminase GAC isoform [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 277.

NUC-7738 regulates β-catenin signalling resulting in reduced proliferation and self-renewal of AML cells

Acute myeloid leukemia (AML) stem cells are required for the initiation and maintenance of the disease. Activation of the Wnt/β-catenin pathway is required for the survival and development of AML leukaemia stem cells (LSCs) and therefore, targeting β-catenin is a potential therapeutic strategy. NUC-7738, a phosphoramidate transformation of 3'-deoxyadenosine (3'-dA) monophosphate, is specifically designed to generate the active anti-cancer metabolite 3'-deoxyadenosine triphosphate (3'-dATP) intracellularly, bypassing key limitations of breakdown, transport, and activation. NUC-7738 is currently in a Phase I/II clinical study for the treatment of patients with advanced solid tumors. Protein expression and immunophenotypic profiling revealed that NUC-7738 caused apoptosis in AML cell lines through reducing PI3K-p110α, phosphorylated Akt (Ser473) and phosphorylated GSK3β (Ser9) resulting in reduced β-catenin, c-Myc and CD44 expression. NUC-7738 reduced β-catenin nuclear expression in AML cells. NUC-7738 also decreased the percentage of CD34+ CD38- CD123+ (LSC-like cells) from 81% to 47% and reduced the total number and size of leukemic colonies. These results indicate that therapeutic targeting of the PI3K/Akt/GSK3β axis can inhibit β-catenin signalling, resulting in reduced clonogenicity and eventual apoptosis of AML cells.

Spatial Analysis of NQO1 in Non-Small Cell Lung Cancer Shows Its Expression Is Independent of NRF1 and NRF2 in the Tumor Microenvironment

Nuclear factor erythroid 2-related factor 1 (NFE2L1, NRF1) and nuclear factor erythroid 2-related factor 2 (NFE2L2, NRF2) are distinct oxidative stress response transcription factors, both of which have been shown to perform cytoprotective functions, modulating cell stress response and homeostasis. NAD(P)H:quinone oxidoreductase (NQO1) is a mutual downstream antioxidant gene target that catalyzes the two-electron reduction of an array of substrates, protecting against reactive oxygen species (ROS) generation. NQO1 is upregulated in non-small cell lung cancer (NSCLC) and is proposed as a predictive biomarker and therapeutic target. Antioxidant protein expression of immune cells within the NSCLC tumor microenvironment (TME) remains undetermined and may affect immune cell effector functions and survival outcomes. Multiplex immunofluorescence was performed to examine the co-localization of NQO1, NRF1 and NRF2 within the tumor and TME of 162 chemotherapy-naïve, early-stage NSCLC patients treated by primary surgical resection. This study demonstrates that NQO1 protein expression is high in normal, tumor-adjacent tissue and that NQO1 expression varies depending on the cell type. Inter and intra-patient heterogenous NQO1 expression was observed in lung cancer. Co-expression analysis showed NQO1 is independent of NRF1 and NRF2 in tumors. Density-based co-expression analysis demonstrated NRF1 and NRF2 double-positive expression in cancer cells is associated with improved overall survival.

The Novel Nucleoside Analogue ProTide NUC-7738 Overcomes Cancer Resistance Mechanisms In Vitro and in a First-In-Human Phase I Clinical Trial

PURPOSE

Nucleoside analogues form the backbone of many therapeutic regimens in oncology and require the presence of intracellular enzymes for their activation. A ProTide is comprised of a nucleoside fused to a protective phosphoramidate cap. ProTides are easily incorporated into cells whereupon the cap is cleaved and a preactivated nucleoside released. 3'-Deoxyadenosine (3'-dA) is a naturally occurring adenosine analogue with established anticancer activity in vitro but limited bioavailability due to its rapid in vivo deamination by the circulating enzyme adenosine deaminase, poor uptake into cells, and reliance on adenosine kinase for its activation. In order to overcome these limitations, 3'-dA was chemically modified to create the novel ProTide NUC-7738.

EXPERIMENTAL DESIGN

We describe the synthesis of NUC-7738. We determine the IC₅₀ of NUC-7738 using pharmacokinetics (PK) and conduct genome-wide analyses to identify its mechanism of action using different cancer model systems. We validate these findings in patients with cancer.

RESULTS

We show that NUC-7738 overcomes the cancer resistance mechanisms that limit the activity of 3'-dA and that its activation is dependent on ProTide cleavage by the enzyme histidine triad nucleotide-binding protein 1. PK and tumor samples obtained from the ongoing first-in-human phase I clinical trial of NUC-7738 further validate our in vitro findings and show NUC-7738 is an effective proapoptotic agent in cancer cells with effects on the NF-κB pathway.

CONCLUSIONS

Our study provides proof that NUC-7738 overcomes cellular resistance mechanisms and supports its further clinical evaluation as a novel cancer treatment within the growing pantheon of anticancer ProTides.

YAP Translocation Precedes Cytoskeletal Rearrangement in Podocyte Stress Response: A Podometric Investigation of Diabetic Nephropathy

Podocyte loss plays a pivotal role in the pathogenesis of glomerular disease. However, the mechanisms underlying podocyte damage and loss remain poorly understood. Although detachment of viable cells has been documented in experimental Diabetic Nephropathy, correlations between reduced podocyte density and disease severity have not yet been established. YAP, a mechanosensing protein, has recently been shown to correlate with glomerular disease progression, however, the underlying mechanism has yet to be fully elucidated. In this study, we sought to document podocyte density in Diabetic Nephropathy using an amended podometric methodology, and to investigate the interplay between YAP and cytoskeletal integrity during podocyte injury. Podocyte density was quantified using TLE4 and GLEPP1 multiplexed immunofluorescence. Fourteen Diabetic Nephropathy cases were analyzed for both podocyte density and cytoplasmic translocation of YAP via automated image analysis. We demonstrate a significant decrease in podocyte density in Grade III/IV cases (124.5 per 10⁶ μm³) relative to Grade I/II cases (226 per 10⁶ μm³) (Student's t-test, p < 0.001), and further show that YAP translocation precedes cytoskeletal rearrangement following injury. Based on these findings we hypothesize that a significant decrease in podocyte density in late grade Diabetic Nephropathy may be explained by early cytoplasmic translocation of YAP.

Abstract 931: From bench to bedside: Using ProTide chemistry to transform 3'-deoxyadenosine into the novel anti-cancer agent Nuc-7738

Background: 3'-deoxyadenosine (3'-dA; also known as cordycepin) is a nucleoside analog that has shown potent anti-cancer activity in non-clinical studies but has not been clinically developed because of its vulnerability to rapid degradation by the circulating enzyme adenosine deaminase (ADA) and its poor uptake into cancer cells. The ProTide NUC-7738 is a pre-activated and protected nucleotide analog (3'-dA 5'monophosphate; 3'-dAMP) specifically designed to overcome the limitations of 3'-dA. NUC-7738's phosphoramidate moiety renders it resistant to ADA degradation. Here we compared NUC-7738 to 3'-dA in several model systems prior to conducting a first-in-class dose-escalation/expansion study of NUC-7738 in patients with advanced cancers.

Materials and Methods: To determine the potency of NUC-7738, IC50 values were measured in multiple cancer cell lines and compared to the parent compound, 3'-dA. Chemical inhibitors of ADA and other 3'-dA processing enzymes were applied to assess the relative ability of NUC-7738 to bypass these pathways. Using genome-wide gene-trap screens and RNA sequencing we compared mechanisms of action (MOA) for NUC-7738 and 3'-dA.

Results: NUC-7738 demonstrated up to 185x greater anti-cancer potency than 3'-dA across a variety of cancer cells lines. Gene trap experiments showed that the intracellular activating enzyme adenosine kinase (ADK) and the hENT1 transporter were amongst the highest enriched genes for 3'-dA, whilst no enrichments for these genes were observed in NUC-7738 treated cells. In support of this, in vitro inhibition assays showed that unlike 3'-dA, NUC-7738 is resistant to ADA breakdown, is not reliant on hENT1 transport for its cellular uptake, and is independent of ADK for its activity. As expected, RNA sequencing analysis demonstrated overlap between the MOA of NUC-7738 and 3'-dA; both cause cancer cell death via the intrinsic apoptosis pathway and suppression of pro-survival signaling. Further investigation of gene candidates was employed in ex-vivo cancer kidney cancer samples.

Conclusion: Phosphoramidate chemistry was used to transform the nucleoside analog 3'-dA into NUC-7738, rendering it resistant to degradation by ADA and enabling it to enter cancer cells independent of nucleoside transporters, both of which contribute to NUC-7738's substantially greater in vitro potency compared to 3'-dA. The gene trap approach allowed a sophisticated comparison of the MOA of NUC-7738 with 3'-dA. By overcoming the resistance mechanisms associated with 3'-dA, NUC-7738 generates higher levels of the active anti-cancer metabolite in cancer cells. These data supported the initiation of NuTide:701, a first-in-human Phase I study assessing the safety, tolerability, pharmacokinetics and pharmacodynamics of NUC-7738 in patients with advanced solid tumors that are resistant to conventional treatment.

Citation Format: Hagen Schwenzer, Michaela Serpi, Valentina Ferrari, James Chettle, Josephine Morris, Ruud van Stiphout, Erica de Zan, Sebastian Nijman, Mustafa Elshani, Mary Kudsy, David Harrison, Gareth Bond, Sarah P. Blagden. From bench to bedside: Using ProTide chemistry to transform 3'-deoxyadenosine into the novel anti-cancer agent Nuc-7738 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 931.

Tissue-Specific Immunopathology in Fatal COVID-19

Rationale: In life-threatening coronavirus disease (COVID-19), corticosteroids reduce mortality, suggesting that immune responses have a causal role in death. Whether this deleterious inflammation is primarily a direct reaction to the presence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) or an independent immunopathologic process is unknown.

Objectives: To determine SARS-CoV-2 organotropism and organ-specific inflammatory responses and the relationships among viral presence, inflammation, and organ injury.

Methods: Tissue was acquired from 11 detailed postmortem examinations. SARS-CoV-2 organotropism was mapped by using multiplex PCR and sequencing, with cellular resolution achieved by in situ viral S (spike) protein detection. Histologic evidence of inflammation was quantified from 37 anatomic sites, and the pulmonary immune response was characterized by using multiplex immunofluorescence.

Measurements and Main Results: Multiple aberrant immune responses in fatal COVID-19 were found, principally involving the lung and reticuloendothelial system, and these were not clearly topologically associated with the virus. Inflammation and organ dysfunction did not map to the tissue and cellular distribution of SARS-CoV-2 RNA and protein between or within tissues. An arteritis was identified in the lung, which was further characterized as a monocyte/myeloid-rich vasculitis, and occurred together with an influx of macrophage/monocyte-lineage cells into the pulmonary parenchyma. In addition, stereotyped abnormal reticuloendothelial responses, including excessive reactive plasmacytosis and iron-laden macrophages, were present and dissociated from viral presence in lymphoid tissues.

Conclusions: Tissue-specific immunopathology occurs in COVID-19, implicating a significant component of the immune-mediated, virus-independent immunopathologic process as a primary mechanism in severe disease. Our data highlight novel immunopathologic mechanisms and validate ongoing and future efforts to therapeutically target aberrant macrophage and plasma-cell responses as well as promote pathogen tolerance in COVID-19.

Abstract C122: NUC-7738, a novel ProTide modification of 3’-deoxyadenosine, activates AMPK and kills renal cancer cells in vitro

Background: Cordycepin or 3′-deoxyadenosine inhibits the growth of cancer cells by several possible mechanisms. The ProTide NUC-7738, a phosphoramidate transformation of cordycepin, is designed to overcome cancer resistance mechanisms through direct release of 3’-deoxyadenosine monophosphate in cells. We hypothesized that it might activate AMP-activated protein kinase (AMPK), the key cellular energy sensor, and thus disrupt metabolic homeostasis in cancer cells. Clear cell renal cell carcinoma (ccRCC) is characterized by lipid accumulation due to dysregulation of the genes fundamental in metabolic pathways and so this disease might be a promising target for metabolic treatment. Phosphorylation of AMPK (pAMPK) is associated with downregulation of mTOR signalling, highlighting the potential of NUC-7738 to regulate this important cancer pathway. Methods: The expression of pAMPK and AMPK in ccRCC from 293 patients was analyzed by immunofluorescence, images were captured digitally and were analyzed using QuPath software. The effect of NUC-7738 on the growth and confluence of nine renal cancer cell lines was assessed using SRB assay and Celigo scanner, under both 0.5% oxygen and normoxic conditions. Western blotting was used to assess changes in the ratio of pAMPK:AMPK caused by NUC-7738 and results read using LiCor Odyssey. Effect of NUC-7738 on AMPK activation in ex vivo ccRCC tissue slices was analyzed using immunofluorescence and QuPath software. Results: Whereas AMPK was widely expressed in ccRCC, pAMPK was focal and very heterogeneous. Cell lines by contrast strongly expressed pAMPK, but this was reduced when culture conditions were altered to be more physiologically appropriate through reduction of oxygen tension and lowering glucose levels. NUC-7738 inhibited the growth of renal cancer cell lines under both hypoxic and normoxic conditions, and increased pAMPK levels were noted after 1 hour, 6 hours, 24 hours, and 48 hours treatment, with inhibition of mTOR activity predominantly observed after 48 hours. NUC-7738 also increased pAMPK levels in ex vivo ccRCC tissue slices. Conclusion: Activation of AMPK was generally low in both primary ccRCC tissue and cell lines grown under physiologically appropriate conditions. NUC-7738 caused activation of AMPK in ex vivo ccRCC tissue slices and in cell lines, and demonstrated efficacy against cell lines in both normoxic and hypoxic conditions. Renal cancer tissue typically has low expression of pAMPK, raising the prospect that AMPK modulation may offer a therapeutic option for ccRCC. These results suggest that inhibition of the mTOR pathway may be one of the anti-cancer mechanisms through which NUC-7738 exerts its activity.

Citation Format: Mary Kudsy, Mustafa Elshani, Sarah Puthur, In Hwa Um, Grant D. Stewart, Maeve Rahilly, Alex Chapman, Michelle Myers, David J. Harrison. NUC-7738, a novel ProTide modification of 3’-deoxyadenosine, activates AMPK and kills renal cancer cells in vitro [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2019 Oct 26-30; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2019;18(12 Suppl):Abstract nr C122. doi:10.1158/1535-7163.TARG-19-C122

Podocyte injury elicits loss and recovery of cellular forces

In the healthy kidney, specialized cells called podocytes form a sophisticated blood filtration apparatus that allows excretion of wastes and excess fluid from the blood while preventing loss of proteins such as albumin. To operate effectively, this filter is under substantial hydrostatic mechanical pressure. Given their function, it is expected that the ability to apply mechanical force is crucial to the survival of podocytes. However, to date, podocyte mechanobiology remains poorly understood, largely because of a lack of experimental data on the forces involved. We perform quantitative, continuous, nondisruptive, and high-resolution measurements of the forces exerted by differentiated podocytes in real time using a recently introduced functional imaging modality for continuous force mapping. Using an accepted model for podocyte injury, we find that injured podocytes experience near-complete loss of cellular force transmission but that this loss of force is reversible under certain conditions. The observed changes in force correlate with F-actin rearrangement and reduced expression of podocyte-specific proteins. By introducing robust and high-throughput mechanical phenotyping and by demonstrating the significance of mechanical forces in podocyte injury, this research paves the way to a new level of understanding of the kidney. In addition, in an advance over established force mapping techniques, we integrate cellular force measurements with immunofluorescence and perform continuous long-term force measurements of a cell population. Hence, our approach has general applicability to a wide range of biomedical questions involving mechanical forces.