REH Cell Line Research Articles

Exploring the effects of Merkel cell polyomavirus T antigens expression in REH and MCC13 cells by methylome and transcriptome profiling.

Merkel cell carcinoma (MCC) is a rare, aggressive skin cancer with a tripled incidence in the US and Europe over the past decade. Around 80% of MCC is linked to Merkel cell polyomavirus, but the cell of origin remains unknown. We stably introduced Merkel cell polyomavirus (MCPyV)-sT) and LT antigens to MCC13 and REH cell lines, analyzing DNA methylation and gene transcriptional regulation. Gene ontology analysis assessed MCPyV effects, and integrative analysis correlated gene expression and methylation. Expression patterns were compared with 15 previously sequenced primary MCCs. We found that MCPyV-LT induces DNA methylation changes in both cell lines, while MCPyV-sT only affected REH cells. Greater gene expression changes are observed in MCC13 cells, with upregulated genes associated with cellular components and downregulated genes related to biological processes. Integrative analysis of differentially expressed genes (DEG) and differentially methylated regions (DMR) of REH cell lines revealed that no genes were commonly methylated and differentially expressed. The study compared DEGs and DMG in MCC13 and REH cells to overlapping genes in MCPyV-positive cell lines (MKL1, MKL2, and WaGa), identifying hypomethylated genes in the gene body and hypermethylated genes at TSS1500. GO analysis of the two cell lines showed that MCPyV-TAs can downregulate genes in MHC-I pathways; this downregulation offers a target that can be used to create novel and efficient MCC immunotherapy approaches. Finally, it was confirmed that MCPyV-LT controls gene expression in MCC tissues using an integrative investigation of DNA methylation and gene expression.

A multiomic characterization of the leukemia cell line REH using short- and long-read sequencing.

The B-cell acute lymphoblastic leukemia (ALL) cell line REH, with the t(12;21) ETV6::RUNX1 translocation, is known to have a complex karyotype defined by a series of large-scale chromosomal rearrangements. Taken from a 15-yr-old at relapse, the cell line offers a practical model for the study of pediatric B-ALL. In recent years, short- and long-read DNA and RNA sequencing have emerged as a complement to karyotyping techniques in the resolution of structural variants in an oncological context. Here, we explore the integration of long-read PacBio and Oxford Nanopore whole-genome sequencing, IsoSeq RNA sequencing, and short-read Illumina sequencing to create a detailed genomic and transcriptomic characterization of the REH cell line. Whole-genome sequencing clarified the molecular traits of disrupted ALL-associated genes including CDKN2A, PAX5, BTG1, VPREB1, and TBL1XR1, as well as the glucocorticoid receptor NR3C1 Meanwhile, transcriptome sequencing identified seven fusion genes within the genomic breakpoints. Together, our extensive whole-genome investigation makes high-quality open-source data available to the leukemia genomics community.

Abstract 541: Establishment of Inotuzumab ozogamicin resistant leukemia cell lines; Focusing on p-gp and DNA damage repair for overcoming drug resistance

Abstract Introduction: Inotuzumab Ozogamicin (IO) is a humanized anti-CD22 monoclonal antibody conjugated with chalicheamicin, which causes single- and double-strand DNA breaks. Although IO shows a high CR/CRi rate in relapsed/refractory CD22-positive B-cell acute lymphoblastic leukemia (ALL), the duration of remission is short due to early acquisition of resistance. Therefore, the present study attempted to enhance the cytotoxicity of IO by focusing on polyadenosine diphosphate-ribose polymerase (PARP) inhibition. Furthermore, IO-resistant cell lines were newly established to investigate the mechanism of IO resistance. Methods: Reh cell line derived from Ph-negative B-ALL cells was used. To establish IO-resistant cell lines, Reh cells were long-term exposed to IO, followed by limiting dilution. FACS analysis evaluated the CD22 positivity and the induction of apoptosis. WTS assay determined the cell growth inhibition effects. The Comet assay quantitatively assessed DNA damage. Gene expression profiles were determined by using DNA microarray. Results: The 50%-inhibitory concentration (IC50) of IO was 2.1 ng/mL in Reh cells. Reh cells were synergistically sensitized to IO by the addition of non-toxic concentrations of PARP inhibitors, olaparib or talazoparib, with the Combination Index of 0.19 and 0.42, respectively. Moreover, these combinations augmented the induction of apoptosis (23.5% in IO alone, 51.7% in IO + olaparib, 66.1% in IO + talazoparib). The Comet assay demonstrated that DNA strand breaks observed 1h after IO administration were repaired 6h later. In the combination of IO with olaparib or talazoparib, DNA damage remained even at 6h, suggesting the inhibition of DNA repair by PARP inhibitors. Next, six IO-resistant cell lines were established with IC50 more than 60-fold that of parental cells. All these cell lines kept CD22 expression. These cell lines were also resistant to apoptosis induced by IO. In addition of olaparib or talazoparib to IO, the IC50 of IO decreased by 40% to 70% in 6 IO-resistant cells. These combinations also augmented the induction of apoptosis (24.2% in IO alone, 45.3% in IO+olaparib, and 56.8% in IO+talazoparib). DNA microarray was performed to compare gene expression profiles between parental and IO-resistant cell lines. ABCB1 (p-gp), a drug efflux pump that causes multi-drug resistance, was overexpressed in resistant cell lines. Moreover, the addition of p-gp inhibitor, PSC-833, to IO enhanced the cell growth inhibition and induction of apoptosis due to more DNA strand break. Conclusion: The present study demonstrated that the combination of IO with PARP inhibitors exerted synergistic cytotoxicity via the inhibition of DNA repair. In addition, it was suggested that overexpression of p-gp caused IO resistance, which was partially reversed with the combination of PARP inhibitors or a p-gp inhibitor. Citation Format: Naoko Ida, Miyuki Okura, Naoko Hosono, Takahiro Yamauchi. Establishment of Inotuzumab ozogamicin resistant leukemia cell lines; Focusing on p-gp and DNA damage repair for overcoming drug resistance [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 541.

Algerian Propolis from Distinct Geographical Locations: Chemical Profiles, Antioxidant Capacity, Cytotoxicity and Inhibition of 5-Lipoxygenase Product Biosynthesis.

Propolis was collected from honeybee hives in three geographically distinct Algerian climates and extracts were characterized for composition and bioactivity. Bees were identified as native subspecies using an in-silico DraI mtDNA COI-COII test. Over 20 compounds were identified in extracts by LC-MS. Extracts from the Medea region were more enriched in phenolic content (302±28 mg GAE/g of dry extract) than those from Annaba and Ghardaia regions. Annaba extracts had the highest flavonoid content (1870±385 mg QCE/g of dry extract). Medea extracts presented the highest free-radical scavenging activity (IC50=13.5 μg/mL) using the DPPH radical assay while Ghardaia extracts from the desert region were weak (IC50>100 μg/mL). Antioxidant activities measured using AAPH oxidation of linoleic acid were similar in all extracts with IC50 values ranging from 2.9 to 4.9 μg/mL. All extracts were cytotoxic (MTT assay) and proapoptotic (Annexin-V) against human leukemia cell lines in the low μg/mL range, although the Annaba extract was less active against the Reh cell line. Extracts inhibited cellular 5-lipoxygenase product biosynthesis with IC50 values ranging from 0.6 to 3.2 μg/mL. Overall, examined propolis extracts exhibited significant biological activity that warrant further characterization in cellular and in vivo models.

Comparison of high-throughput single-cell RNA-seq methods for ex vivo drug screening.

Functional precision medicine (FPM) aims to optimize patient-specific drug selection based on the unique characteristics of their cancer cells. Recent advancements in high throughput ex vivo drug profiling have accelerated interest in FPM. Here, we present a proof-of-concept study for an integrated experimental system that incorporates ex vivo treatment response with a single-cell gene expression output enabling barcoding of several drug conditions in one single-cell sequencing experiment. We demonstrate this through a proof-of-concept investigation focusing on the glucocorticoid-resistant acute lymphoblastic leukemia (ALL) E/R+Reh cell line. Three different single-cell transcriptome sequencing (scRNA-seq) approaches were evaluated, each exhibiting high cell recovery and accurate tagging of distinct drug conditions. Notably, our comprehensive analysis revealed variations in library complexity, sensitivity (gene detection), and differential gene expression detection across the methods. Despite these differences, we identified a substantial transcriptional response to fludarabine, a highly relevant drug for treating high-risk ALL, which was consistently recapitulated by all three methods. These findings highlight the potential of our integrated approach for studying drug responses at the single-cell level and emphasize the importance of method selection in scRNA-seq studies. Finally, our data encompassing 27327 cells are freely available to extend to future scRNA-seq methodological comparisons.

Methazolamide Reduces the AQP5 mRNA Expression and Immune Cell Migration-A New Potential Drug in Sepsis Therapy?

Sepsis is a life-threatening condition caused by the dysregulated host response to infection. Novel therapeutic options are urgently needed and aquaporin inhibitors could suffice as aquaporin 5 (Aqp5) knockdown provided enhanced sepsis survival in a murine sepsis model. Potential AQP5 inhibitors provide sulfonamides and their derivatives. In this study, we tested the hypothesis that sulfonamides reduce AQP5 expression in different conditions. The impact of sulfonamides on AQP5 expression and immune cell migration was examined in cell lines REH and RAW 264.7 by qPCR, Western blot and migration assay. Subsequently, whether furosemide and methazolamide are capable of reducing AQP5 expression after LPS incubation was investigated in whole blood samples of healthy volunteers. Incubation with methazolamide (10-5 M) and furosemide (10-6 M) reduced AQP5 mRNA and protein expression by about 30% in REH cells. Pre-incubation of the cells with methazolamide reduced cell migration towards SDF1-α compared to non-preincubated cells to control level. Pre-incubation with methazolamide in PBMCs led to a reduction in LPS-induced AQP5 expression compared to control levels, while furosemide failed to reduce it. Methazolamide appears to reduce AQP5 expression and migration of immune cells. However, after LPS administration, the reduction in AQP5 expression by methazolamide is no longer possible. Hence, our study indicates that methazolamide is capable of reducing AQP5 expression and has the potential to be used in sepsis prophylaxis.

Identifying a core protein signature of small extracellular vesicles derived from B-cell precursor acute lymphoblastic leukaemia.

Acute paediatric leukaemia is diagnosed and monitored via bone marrow aspirate assessment of blasts as a measure of minimal residual disease. Liquid biopsies in the form of blood samples could greatly reduce the need for invasive bone marrow aspirations, but there are currently no blood markers that match the sensitivity of bone marrow diagnostics. Circulating extracellular vesicles (EVs) represent candidate biomarkers that may reflect the blast burden in bone marrow, and several studies have reported on the utility of EVs as biomarkers for adult haematological malignancies. Increased levels of EVs have been reported for several haematological malignancies, and we similarly report here elevated EV concentrations in plasma from paediatric BCP-ALL patients. Plasma EVs are very heterogeneous in terms of their cellular origin, thus identifying a cancer selective EV-marker is challenging. Here, we undertook a reductionistic approach to identify protein markers selectively associated to plasma EVs derived from BCP-ALL patients. The EV proteome of primary BCP-ALL cell-derived EVs were compared against EVs from healthy donor B cells and the BCP-ALL cell line REH, and further against EVs isolated from plasma of healthy paediatric donors and paediatric BCP-ALL patients. With this approach, we identified a signature of 6 proteins (CD317, CD38, IGF2BP1, PCNA, CSDE1, and GPR116) that were specifically identified in BCP-ALL derived EVs only and not in healthy control EVs, and that could be exploited as diagnostic biomarkers.

IGF2BP1 Stabilizes and Inhibits Degradation of Pro-Oncogenic Transcripts in ETV6-RUNX1 Positive B-Cell Acute Lymphoblastic Leukemia

Insulin like growth factor 2 mRNA binding protein 1(IGF2BP1) belongs to a family of oncofetal proteins expressed in embryonic life followed by re-emergence during malignant transformation. It is an RNA binding protein known to be dysregulated and overexpressed in multiple malignancies. We have demonstrated its specific overexpression in ETV6-RUNX1 translocated B-cell Acute Lymphoblastic Leukemia (B-ALL). RNA immunoprecipitation using anti-IGF2BP1 antibody, followed by sequencing (RIP-Seq) in Reh cell line (ETV6-RUNX1 positive) identified multiple oncogenic transcripts belonging to the non-canonical NF-κB and PI3K signaling pathways. Overexpression of genes from these pathways (IL6ST, GADD45A, NFAT5, MDM2, CDK6, FGFR1) was also observed in our B-ALL patient samples specifically in the ETV6-RUNX1 positive patients (Total n=111; ETV6-RUNX1 positive: 39) in comparison to MACS sorted, peripheral blood CD19 positive B-cells from healthy volunteers as well as in comparison to non ETV6-RUNX1 translocated B-Acute lymphoblastic leukemia patients. This was also corroborated by public B-ALL gene expression data from the TARGET database in the cBioportal. However, knockout of IGF2BP1 in Reh cell line using CRISPR-Cas9 technology led to significant downregulation of only some of these targets. This implied that the expression of some of the mRNA targets binding to IGF2BP1 was not influenced by its knockout. To better elucidate the role played by IGF2BP1 in the stability of its binding mRNA targets, we decided to study the rate of degradation of target transcripts. mRNA stability was assessed to quantify the rate of degradation of target mRNA after inhibition of transcription using actinomycin. Since actinomycin causes global transcriptional block, we first quantified the effect of actinomycin on the expression of multiple (n=7) housekeeping genes against each other, and selected 3 ( HGPRT, B2M and PPIA) which showed least change after actinomycin treatment. These 3 housekeeping genes were used for further quantification of target transcripts. Dual specificity phosphatase 1( DUSP1) a transcript known to be rapidly degraded, was used to validate the transcriptional inhibition by actinomycin. We quantified the rate of degradation of target transcripts in Reh cells using BTYNB, a small molecule inhibitor of IGF2BP1. BTYNB binds to IGF2BP1 and prevents binding to target transcripts which leads to their destabilization and reduced half-life. We used a combination of BTYNB and actinomycin to study rate of degradation after IGF2BP1 inhibition. Effect of IGF2BP1 on the stability of three target mRNAs involved in non-canonical NF-κB signalling pathway was quantified by comparing their rate of degradation in BTYNB treated cells against the DMSO (vehicle) treated cells. Rate of degradation was measured by actinomycin treatment of both these groups followed by hourly RNA isolation and qPCR over 12 hours. MYC is a known mRNA binding target of IGF2BP1. BTYNB was also shown to decrease the expression of MYC mRNA by accelerating its degradation. Simultaneously there was an increase in the expression of MYC pre-mRNA indicating a possible for IGF2BP1 in splicing of MYC RNA. In the NF-κB signalling pathway, we had previously identified that NFAT5 expression was not altered significantly after IGF2BP1 knockout even though it binds to IGF2BP1. BTYNB followed by actinomycin treatment demonstrated a dramatic increase in the rate of degradation of NFAT5 implying that IGF2BP1 prevents the degradation of NFAT5 transcript and directly influences its stability. Interestingly, the rates of degradation of other targets like IL6ST and GADD45 were not altered. These findings suggest a heterogeneous influence of IGF2BP1 on the stability of its target transcripts. Some of the transcripts seem to be directly stabilised by IGF2BP1 while others may be influenced indirectly. Taken together, these findings suggest a role of IGF2BP1 in multiple phases of the RNA synthesis and degradation warranting further studies to elucidate role of IGF2BP1 in each of these steps. IGF2BP1 appears to have a critical role in preventing the degradation and stabilizing MYC and NFAT5 transcripts.

Combining Inotuzumab Ozogamicin (IO) with PARP Inhibitors, Olaparib and Talazoparib, Exerts Synergistic Cytotoxicity By Inhibiting the Repair of IO-Induced DNA Strand Breaks in IO-Resistant ALL Cells

[Introduction]Inotuzumab ozogamicin (IO) is highly effective in the treatment of relapsed/refractory CD22-positive B-acute lymphoblastic leukemia (B-ALL). IO exerts the antileukemic effect via DNA single- and double-strand breaks induced by calicheamicin. Although IO has been reported to show more than 80% response rate, the duration of remission is only 4.6 months, suggesting the early acquisition of drug resistance. Thus, it is crucial to elucidate the mechanism of resistance to IO and overcome it. Polyadenosine diphosphate-ribose polymerase (PARP) inhibitors, such as olaparib and talazoparib, show the antitumor effect by inhibiting DNA repair. This study was conducted to enhance the antitumor effect of IO by inhibiting IO-induced DNA damage repair using PARP inhibitors. The study attempted to overcome the resistance of B-ALL cell lines developed to be IO-resistant. [Methods]Ph-negative, CD22-positive B-ALL Reh cell line was used to determine the cytotoxicity of IO and PARP inhibitors. Inotuzumab ozogamicin was kindly provided by Pfizer. Six IO-resistant cell lines were newly established by long-term exposure of Reh cells to IO, followed by the limiting dilution. FACS analysis evaluated CD22 expression. WTS assay and Annexin-V positivity were used to determine the antileukemic effects. The Comet assay assessed the DNA repair function. The DNA microarray compared gene expression between Reh and IO-resistant Reh clones. [Results] The growth inhibition effect of IO was significantly augmented by the addition of the minimally toxic concentration of olaparib or talazoparib in Reh cells. The combination index values were 0.19 and 0.42, respectively, demonstrating a strong synergism. Combining IO with olaparib or talazoparib increased IO-induced apoptosis compared to single-agent IO. The apoptosis rates induced by 20 ng/mL IO with minimally toxic concentrations of olaparib or talazoparib were 51.7% and 66.1%, respectively, showing significantly higher apoptosis rates than IO alone (23.5%). Assessment of DNA strand breaks using the Comet assay showed that the recovery of IO-induced DNA damage was inhibited in the presence of PARP inhibitors, and DNA strand breaks persisted. Next, six IO-resistant Reh (Reh-IO-R) cell lines were established as described above. The expressions of CD22 were more than 60%. All 6 cell lines had more than 60-fold resistance to IO with the 50%-inhibitory concentration (IC 50) values 474.3～782.3 ng/mL, compared with that of Reh cells (2.1 ng/mL). The IC 50 values of olaparib or talazoparib were similar to Reh and Reh-IO-R cell lines. When IO was combined with olaparib or talazoparib, the growth of Reh-IO-R cells was inhibited, with median IC 50 values were 359.4[290.3-406.2] and 179.1[59.3-240.5] ng/mL, respectively. This combination also remarkably increased apoptosis induction in Reh-IO-R cells. The apoptosis rate of Reh cells at 100 ng/mL IO alone was 77%, whereas the apoptosis rate of 6 Reh-IO-R cell lines averaged 5.9% [5.7-6.6%]. The median percentage of apoptosis in Reh-IO-R cell lines was 12.0% by IO + olaparib and 17.1% by IO + talazoparib. Furthermore, synergism was obtained in Reh-IO-R cell lines with the combination of 1,000 ng/mL IO with olaparib or talazoparib. The median percentage of apoptotic cell death was 24.2% by IO 1,000 ng/mL alone and 45.3% by the IO+olaparib, and 56.8% by the IO+talazoparib. These results suggest that the potentiating effect of PARP inhibitors would be attributed to more DNA cleavage occurring. The expression of genes ( ATM, ATR, DNA-PK, CHK1/2, PARP, RAD, ERCC1, BRCA1/2 Ku70/80) related to DNA repair was similar between Reh and Reh-IO-R cells. Of note, ABCB1 (p-gp) was overexpressed in Reh-IO-R cells. These results suggest that the expression of p-gp was one of the mechanisms of the resistance to IO, and the combination of IO and PARP inhibitors was effective to a certain extent in the Reh-IO-R cells expressing p-gp. This would be because the PARP inhibitors were still effective in inhibiting the DNA repair in Reh-IO-R cells where the DNA repair function was not augmented. [Conclusion]The combination of IO with PARP inhibitors synergized the antileukemic effect of IO by inhibiting DNA strand break repair in CD22-positive ALL cell lines and IO-resistant ALL cells, suggesting that these results may contribute to overcoming the IO resistance mechanisms.

Targeting SF3B1 in High-Risk B-Cell Acute Lymphoblastic Leukemia

Introduction B-cell acute lymphoblastic leukemia (B-ALL) is the most common pediatric cancer. The outcomes of young adults with B-ALL are poor, with an event-free survival (EFS) rate of <50%. The prognosis of children with certain types of B-ALL is also poor with an EFS rate of 70%. Therefore, there is a need for new treatments for these children with high-risk B-ALL. RNA splicing alternations have been suggested to contribute to the initiation and/or maintenance of cancer. In B-ALL, dysregulated splicing is reported to be associated with drug resistance and disease relapse. SF3B1 is a core component of the spliceosome and an essential protein in the RNA splicing process. SF3B1 inhibition is therapeutic in many cancers, including myeloid malignancies and T-cell ALL. However, there have been no reports studying the efficacy and the function of spliceosome inhibitors including SF3B1 inhibitors in B-ALL. In this study, we determined the therapeutic potential of pladienolide B (Plad-B), an SF3B1 inhibitor, in B-ALL. Methods SF3B1 mRNA and protein expressions were determined in the cell lines Reh and JM1 and 14 patient samples (standard-risk: 7 samples, high-risk: 7 samples), by qRT-PCR and Western blotting, respectively. Efficacy of Plad-B was tested in two B-ALL cell lines, CD34 positive hematopoietic stem cells (HSCs), and three high-risk patient-derived xenograft (PDX) samples (sample#1: age < 1 year old, sample#2: age > 10 years old, sample#3: relapse), by an MTS assay. In vivo efficacy of Plad-B was tested using an Reh xenograft model and a PDX model. Function of Plad-B was assessed in cell lines by a cell cycle assay, Annexin V assay with flow cytometry, and Western blotting of cleaved PARP and cleaved caspase-3. To determine the changes in the splicing events and apoptosis-associated genes, we are performing RNA-seq at 15min, 30min, 60min, and 24 hours after the treatment. Results SF3B1 mRNA and protein expressions were significantly higher in Reh and JM1 than in hematopoietic monocular cells and CD34-positive HSCs (p < 0.05). SF3B1 protein, but not mRNA, expressions were higher in primary patient samples than in hematopoietic monocular cells and CD34-positive HSCs. There was no significant difference in the mRNA and protein expressions between standard-risk and high-risk groups. Plad-B treatments showed significant cytotoxicity in both Reh and JM1 cell lines with IC50 of 1.2nM and 0.6nM, respectively, at 48 hours after treatment. Plad-B did not show cytotoxicity at the same tested concentrations in CD34-positive HSCs. Plad-B treatments showed similarly significant cytotoxicity in three harvested PDXs with IC50 of 0.7nM, 2.5nM, and 1.1nM, respectively, at 48 hours after the treatment. Plad-B, at a dose of 10 mg/kg 2 times on 1 and 2 days, significantly prolonged survival in the Reh xenograft mouse model, with a median survival time of 33.5 days compared with 25.0 days in the control group (p < 0.05) (Figure 1). Plad-B, at a dose of 10 mg/kg 4 times on 1, 3, 5, and 7 days, prolonged survival in the PDX mouse model (sample#1), with a median survival time of 38.0 days compared with 32.0 days in the control group (p = 0.14). Cell cycle arrest was observed at 24 hours after Plad-B treatment in both Reh (Control: 12.6%, Plad-B 3nM: 23.8% in G2/M phase, p < 0.001) and JM1 (Control: 20.6%, Plad-B 3nM: 35.1% in G2/M phase, p < 0.01). Plad-B caused significant cell apoptosis in Reh (Control: 3.2%, Plad-B 3nM: 24.1% with Annexin V positive cells, p < 0.001) and JM1 (Control: 5.9%, Plad-B 3nM: 31.2% with Annexin V positive cells, p < 0.001) cells at 24 hours after treatment. Plad-B also caused significant cell apoptosis in harvested PDX sample #1 (Control: 29.8.%, Plad-B 3nM: 47.6% with Annexin V positive cells, p < 0.001) at 24 hours after treatment. Western blotting of anti-cleaved PARP and anti-cleaved caspase-3 showed that the expression of cleaved caspase-3 and cleaved PARP were significantly augmented in Reh and JM1 cells after Plad-B treatment. RNA seq data is currently being analyzed. Conclusions SF3B1 is highly expressed in B-ALL cell lines and in primary patient samples regardless of the risk group. Plad-B showed significant cytotoxicity in B-ALL leading leukemia cells to G2/M cycle arrest and apoptosis. Plad-B treatment demonstrated in vivo therapeutic efficacy in pre-clinical B-ALL animal models. These data suggest therapeutic potential of SF3B1 inhibition in B-ALL including high-risk patients.

Design and synthesis of novel 1,2,3,4-tetrazines as new anti-leukemia cancer agents.

A series of novel 1,2,3,4-tetrazines were designed and synthesized. 1 H-NMR spectroscopy, 13 C NMR spectroscopy, and HRMS were used to determine the structures of this novel compounds. Computational approaches suggested that DHFR is a putative target for the newly synthesized 11 compounds. Extensive molecular dynamics simulations followed by molecular docking simulations were employed to evaluate DHFR as a potential target protein. The anticancer activities of the compounds were evaluated against five different types of leukemia cell lines (Jurkat, Nalm-6, Reh, K562, and Molt-4) and one non-leukemic cell line (Hek293T) by MTT test in vitro and imatinib was used as a control drug. Among these compounds, 3a exhibited the best activity against all the leukemic cell lines, except Reh cell line. For Nalm-6, K562, Jurkat, and Molt-4 cell lines, IC50 values were found to be 15.98, 19.12, 23.15, and 25.80 μM, respectively. Our work focuses on the synthesis of original and novel 1,2,3,4-tetrazine derivatives while contributing to the ongoing effort to discover more potent new antileukemia agents.

RNA binding protein IGF2BP1 synergizes with ETV6-RUNX1 to drive oncogenic signaling in B-cell Acute Lymphoblastic Leukemia

BackgroundAcute lymphoblastic leukemia (ALL) is the most common pediatric hematological malignancy, with ETV6::RUNX1 being the most prevalent translocation whose exact pathogenesis remains unclear. IGF2BP1 (Insulin-like Growth Factor 2 Binding Protein 1) is an oncofetal RNA binding protein seen to be specifically overexpressed in ETV6::RUNX1 positive B-ALL. In this study, we have studied the mechanistic role of IGF2BP1 in leukemogenesis and its synergism with the ETV6::RUNX1 fusion protein.MethodsGene expression was analyzed from patient bone marrow RNA using Real Time RT-qPCR. Knockout cell lines were created using CRISPR-Cas9 based lentiviral vectors. RNA-Seq and RNA Immunoprecipitation sequencing (RIP-Seq) after IGF2BP1 pulldown were performed using the Illumina platform. Mouse experiments were done by retroviral overexpression of donor HSCs followed by lethal irradiation of recipients using a bone marrow transplant model.ResultsWe observed specific overexpression of IGF2BP1 in ETV6::RUNX1 positive patients in an Indian cohort of pediatric ALL (n=167) with a positive correlation with prednisolone resistance.IGF2BP1 expression was essential for tumor cell survival in multiple ETV6::RUNX1 positive B-ALL cell lines. Integrated analysis of transcriptome sequencing after IGF2BP1 knockout and RIP-Seq after IGF2BP1 pulldown in Reh cell line revealed that IGF2BP1 targets encompass multiple pro-oncogenic signalling pathways including TNFα/NFκB and PI3K-Akt pathways. These pathways were also dysregulated in primary ETV6::RUNX1 positive B-ALL patient samples from our center as well as in public B-ALL patient datasets. IGF2BP1 showed binding and stabilization of the ETV6::RUNX1 fusion transcript itself. This positive feedback loop led to constitutive dysregulation of several oncogenic pathways.Enforced co-expression of ETV6::RUNX1 and IGF2BP1 in mouse bone marrow resulted in marrow hypercellularity which was characterized by multi-lineage progenitor expansion and strong Ki67 positivity. This pre-leukemic phenotype confirmed their synergism in-vivo. Clonal expansion of cells overexpressing both ETV6::RUNX1 and IGF2BP1 was clearly observed. These mice also developed splenomegaly indicating extramedullary hematopoiesis.ConclusionOur data suggest a combined impact of the ETV6::RUNX1 fusion protein and RNA binding protein, IGF2BP1 in activating multiple oncogenic pathways in B-ALL which makes IGF2BP1 and these pathways as attractive therapeutic targets and biomarkers.

Cathepsin B Is Not an Intrinsic Factor Related to Asparaginase Resistance of the Acute Lymphoblastic Leukemia REH Cell Line.

L-Asparaginase (ASNase) is a biopharmaceutical used as an essential drug in the treatment of acute lymphoblastic leukemia (ALL). Yet, some cases of ALL are naturally resistant to ASNase treatment, which results in poor prognosis. The REH ALL cell line, used as a model for studying the most common subtype of ALL, is considered resistant to treatment with ASNase. Cathepsin B (CTSB) is one of the proteases involved in the regulation of in vivo ASNase serum half-life and it has also been associated with the progression and resistance to treatment of several solid tumors. Previous works have shown that, in vitro, ASNase is degraded when incubated with REH cell lysate, which is prevented by a specific CTSB inhibitor, suggesting a function of this protease in the ASNase resistance of REH cells. In this work, we utilized a combination of CRISPR/Cas9 gene targeting and enzymatic measurements to investigate the relevance of CTSB on ASNase treatment resistance in the ALL model cell line. We found that deletion of CTSB in REH ALL cells did not confer ASNase treatment sensitivity, thus suggesting that intrinsic expression of CTSB is not a mechanism that drives the resistant nature of these ALL cells to enzymes used as the first-line treatment against leukemia.

Abstract 5655: preclinical development of a novel anti-tslpr bispecific antibody 1b7/cd3 targeting crlf2-rearranged ph-like b-all

Abstract Acute lymphocytic leukemia (ALL) is the most common form of leukemia in childhood and adolescence. Outcomes of relapsed/refractory adult B-ALL remain dismal with long-term survival of less than 10%. Although targeted therapies such as blinatumomab, inotuzumab ozogamicin, and CD19 CAR T cell therapy are a significant treatment advance for patients with B-ALL, there is still an unmet medical need for novel therapies for B-ALL. CRLF2-rearranged B-ALL, a subtype of Philadelphia chromosome-like B-ALL, is a high-risk disease subset with poor long-term outcomes. In an effort to identify new therapeutic targets for B-ALL, we validated by flow cytometry that patients with CRLF2-rearranged Ph-like ALL overexpress thymic stromal lymphopoietin receptor (TSLPR) at levels comparable with CD19. We subsequently generated antibodies against TSLPR from immunized H2L2 Harbor mice through single B cell cloning technology. The lead antibody was further engineered to a CD3-redirecting bispecific antibody (BsAb) using Xencor’s CD3e bispecific antibody technology to create 1B7/CD3 BsAb with an Fc-silent region. 1B7/CD3 BsAb exhibits high affinity binding to both human and cynomolgus monkey CD3e and TSLPR by BLI. Additionally, UHPLC-SEC analysis of 1B7/CD3 shows that this BsAb is stable without any aggregation or degradation present after five weeks incubation at 37 °C. In cell-based analyses,1B7/CD3 BsAb demonstrate potent antigen-specific T cell activation and tumor lysis activity against TSLPR+-REH and MHH-CALL4 cell lines as well as a primary B-ALL patient sample, but none against human peripheral blood mononuclear cells (PBMC) collected from healthy donors. Animal tumor models suggest that 1B7/CD3 triggers a dose-dependent tumor regression or growth inhibition in PBMC humanized TSLPR-REH CDX and BOS-1 PDX models across donors. Correspondingly, T cell activation and expansion were examined by CD69 and CD3+ T cells with the best effect observed at the 1mg/kg dose. 1B7/CD3 exhibits durable PK with T1/2 in NSG mice of up to ten days. Finally, 1B7/CD3 BsAb demonstrated a tolerable safety margin in a two-dose exploratory toxicity study in cynomolgus monkeys with MTD equal to or less than 1mg/kg. Consistent with clinical observation, we observed a transient increase of six major cytokines (IFNγ, IL-6, IL-8, IL-10, MCP-1 and TNFα) 4hr post the initial dosing, but no notable induction of cytokine levels after the second dosing (except for IL-8). Thus, our preclinical data provide the framework for the clinical evaluation of 1B7/CD3 BsAb in patients with CRLF2-rearranged B-ALL. Citation Format: Ze Tian, chunhua shi, Amin AI-Shami, GuoJun Yong, Jason K Allen, Jill Wardell Olson, Melinda G Smith, Qing Chang, Qing Shi, Junping You, Michelle A Gonzalez, Timothy E Lofton, Jasbir Kaur, Qi Zhang, DongXing Zha, Nitin Jain, Marina Y Konopleva, Timothy Heffernan, Jeffrey J Molldrem. preclinical development of a novel anti-tslpr bispecific antibody 1b7/cd3 targeting crlf2-rearranged ph-like b-all. [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 5655.

Cord blood derived NK cells activated in counter with tumor cells.

NK cells are initially known for their ability to kill tumor cells with no prior sensitization. Production of mature and long lasting NK cells from Umbilical Cord Blood (UCB) by using cytokines could be a promising method for immunotherapy. NK cells were generated from cord blood cells using IL2, IL7, and IL15 cytokines and measured expression of CD57 and NKp46 markers. Afterward, their capacity in the elimination of malignant cells (Reh cell line) was evaluated by assessment of interferon-γ (as cytokine production sign) and CD107-a expression (as cytotoxic function symptom) using flow cytometry. Our results showed efficient NKp46 + , and CD57 + NK cells generated on day 14. Also, expression of CD107-a and IFN-γ following co-culture with Reh cell lines significantly increased in comparison to the control. Taken together, we have reported one of the best culture conditions for the generation of CD57 + NK cells with on feeder cells and showed appropriate capacity in counter reh cell lines as a target.

Niclosamide Inhibits the Growth of Acute Lymphoblastic Leukemia Cells By Increasing Intracellular ROS and Activation of p53-PUMA/NOXA

Acute lymphoblastic leukemia (ALL) is a heterogeneous clonal malignancy originated from B- or T-cell lymphoid precursor cells. The prognosis is extremely poor in refractory or relapsed cases. Niclosamide is an FDA-approved oral anthelmintic drug with anti-cancer property. In the present study, we investigated the anti-leukemic effect of niclosamide in ALL cells in vitro and in vivo. ALL cell lines REH and NALM-6, and primary cells of patients with ALL were treated with niclosamide according to the concentration gradient, and then detected by trypan blue, MTS, and soft agar colony assays. The transcriptional and translational levels of apoptosis/anti-apoptosis-related genes were assessed by immunoblotting and quantitative real-time PCR. Flow cytometry was used to detect the effect of niclosamide on apoptosis of ALL cells, mitochondrial membrane potential, and intracellular specific reactive oxygen species (ROS) levels. For animal studies, we generated a mouse xenograft model with NOD prkdc-/-IL-2Rg-/- mice intravenously engrafted with NALM-6-luc cells, the NALM-6 cells infected with retrovirus expressing luciferase. Mice were treated with 25 mg/kg/day niclosamide or solvent twice a day intraperitoneally. The effect of niclosamide against leukemia cells in mice was dynamically evaluated by an in vivo imaging system. Flow cytometry was used to analyze the percentage of leukemia cells in spleens and bone marrows of sacrificed mice. The overall survival of mice was evaluated by Kaplan-Meier survival curve. In the cell viability assay, we found that niclosamide effectively inhibited REH, NALM-6 and primary ALL cells with IC50 values of 1.72, 3.58 and 1.36 μmol/L, respectively. Immunoblotting showed increased levels of pro-apoptotic proteins p53, PUMA, NOXA, cyto C and PARP, but decreased level of anti-apoptotic protein survivin in ALL cells treated with niclosamide in a dose- and time-dependent manner. Flow cytometry showed that niclosamide induced apoptosis and mitochondrial membrane potential in ALL cells. We also found that the level of ROS began to increase in cells treated by niclosamide for 2 hours, which reached the maximum at 8 hours. The treatment of ROS inhibitor N-acetylcysteine (NAC) attenuated niclosamide-induced apoptosis of REH and NALM-6 cells, which reduced by 18.12% and 8.02%, respectively. NAC also inhibited niclosamide-induced accumulation of intracellular p53/PUMA/NOXA proteins in these cells. In the animal study, in vivo imaging system showed significantly reduced tumor burdens in mice treated with niclosamide compared with controls, with bioluminescence signals of 15.53 and 4.04 on day 21, respectively. Mice treated with niclosamide survived longer than controls (32.5 days vs 26.5 days, p < 0.01), which had lower percentage of CD45+ CD19+ leukemia cells in their bone marrows and spleens, compared with the control group (61.10% vs 34.76% and 54.88% vs 26.40%, respectively). In the present study, we found that niclosamide potently inhibited the growth of ALL cells and induced apoptosis via increased levels of ROS and the activation of p53 signaling. Our findings suggest that niclosamide may be a promisingly potent agent for ALL therapy.

Glucocorticoid-Resistant B-Cell Acute Lymphoblastic Leukemic Cells Can be Targeted By BCR-Signaling Inhibition

Glucocorticoids (GCs) remain a backbone component of therapeutic regimens for childhood B-cell acute lymphoblastic leukemia (B-ALL). GCs resistance is a strong prognostic marker of relapse making its understanding an important challenge to be addressed to improve overall patients outcome.Healthy B-cell development is characterized by checkpoints where critical regulatory signaling influences the fate of developing B-cells. These stages are vulnerable for leukemic transformation and as we previously demonstrated, the developmental and functional state of B-ALL cells are of critical importance in treatment failure. Using this developmental framework, we examined the effect of GCs on healthy and malignant B-cells to better understand mediators of GC resistance and ways to overcome it.To define the dynamics of the transcriptional networks surrounding B-cell developmental checkpoints, we performed transcriptomic analysis of sorted pre-proB, pro-B and pre-B cells from 3 healthy donors. We found a coordinated upregulation of B cell receptor (BCR) and Glucocorticoid Receptor (GCR) pathways in healthy B cells during their development. Single cell proteomic analysis of these healthy populations confirmed the coordinated expression of GCR with early B-cell phenotypic markers. Furthermore, in vitro treatment of healthy B-cells with the GC dexamethasone (dex) demonstrated cycling pro-B/pre-B cells to be the most sensitive to GC-induced cell death.Given the importance of GCs in B-ALL treatment, we investigated GCs effects and resistance in NALM6 and REH cell lines. NALM6, expressing high levels of GCR, were significantly sensitive to dex treatment in terms of cell cycle arrest and cell death. By contrast, REH cells were resistant to dex treatment as they lack the GCR. Retroviral transfection of NR3C1 (GCR gene) in REH cells (REH GCR) resulted in acquired sensitivity to dex. To explore the potential crosstalk between GCR and BCR pathways, we also treated cells with BCR signaling inhibitor, dasatinib (das), alone or in combination with dex. While both cell lines survived to treatment with das, the combined treatment increased apoptosis compared to dex alone in NALM6 cells (p=0.0179) and REH GCR cells (p=ns). Whole transcriptome sequencing of dex-resistant cells revealed upregulation of BCR downstream signaling as one of the main pathways associated with resistance.The cell line data implicated active BCR signaling as a path to GCs resistance, so we next analyzed 19 B-ALL primary samples by mass cytometry, after in vitro exposure for 48 hrs to same treatments. Across the entire cohort, dex induced a significant reduction in viability (p=0.0007), compared to vehicle. Treatment with das and dex+das also decreased cell viability compared to vehicle (p=0.0038 and p=0.0002) although was not significant to dex alone. Interestingly dex-resistant cells showed a phenotypic modulation compatible with a late pre-B phenotype with increased CD45 and CD20 expression. In addition, surviving cells showed an activation of downstream targets of BCR signaling such as pSYK, pRPS6 and pCREB that was partially blunted by dasatinib treatment.To understand whether the phenotype and signaling modulation induced by dexamethasone also occurs in patients after treatment with GCs, we analyzed minimal residual disease (MRD) cells following 8 days of treatment with GCs from 9 B-ALL patients. This analysis confirmed our previous findings with MRD cells having same late pre-B cells phenotype and signaling profile as in vitro treated cells.Finally, we tested whether targeting of pre-BCR signaling via dasatinib, could overcome resistance in vivo. We evaluated engraftment of luciferase-expressing NALM6 cells at different timepoints after tail vein injection in mice treated with vehicle, dex, das or dex + das. Bioluminescence analysis revealed a significant reduction of early and late engraftment in the dex + das group compared to vehicle-treated mice. Furthermore, mice receiving the combined treatment also experienced a significant survival advantage as assessed by log rank test (p=0.0002).Taken together these data suggest a coordinated interplay between BCR and GCR pathways in healthy and leukemic B cells. GCs-resistant leukemic cells showed a mature pre-B phenotype that is vulnerable to BCR signaling inhibition in vitro and in vivo suggesting new therapeutic options to overcome GC resistance in childhood B-ALL. DisclosuresBiondi: Bluebird: Other: Advisory Board; Novartis: Honoraria; Incyte: Consultancy, Other: Advisory Board; Amgen: Honoraria; Colmmune: Honoraria. Bava: 10x Genomics: Current Employment. Davis: Jazz Pharmaceuticals: Research Funding; Novartis Pharmaceuticals: Honoraria.

Synergism between IGF2BP1 and ETV6-RUNX1 in the Pathogenesis of ETV6-RUNX1 Positive B-Acute Lymphoblastic Leukaemia

Acute lymphoblastic leukaemia (ALL) is the most common pediatric haematological malignancy with a prevalence of around 85% cases of B cell origin. ETV6-RUNX1 is the most common genetic aberration in childhood B-ALL with a prevalence of around 25% in Western countries and a lower prevalence in Asian countries. ETV6-RUNX1 presence portends a good prognosis in B-ALL. ETV6-RUNX1 translocation has been observed in 1-5% of healthy newborns, indicating that it is not sufficient for leukemogenesis, and the need to accumulate secondary mutations for leukemogenesis.We have previously demonstrated the specific overexpression of Insulin like Growth Factor 2 Binding Protein 1 (IGF2BP1), an oncofetal RNA binding protein, in ETV6-RUNX1 positive B-ALL. Overexpression of the ETV6-RUNX1 fusion protein in 7OZ/3, a murine B-ALL cell line increased endogenous Igf2bp1 levels in a dose dependent manner.Conversely, knockout of IGF2BP1 in Reh-Cas9-GFP expressing B-ALL cell line, a modified version of Reh (cell line positive for ETV6-RUNX1 translocation), using 2 different guide RNAs led to a decrease in the ETV6-RUNX1 transcript expression in the IGF2BP1 KO Reh-Cas9 cells. This was accompanied by a decrease in cell proliferation and increased chemosensitivity to prednisolone.A similar phenotype was observed in Reh-Cas9 cells after knockout of ETV6-RUNX1 fusion transcript hinting towards a synergism between the two proteins in tumour cell survival and chemosensitivity. Interestingly, there appears to be a positive correlation between prednisolone resistance and ETV6-RUNX1 positivity in our patient cohort too, thus supporting the in vitro finding. Previous studies have shown the binding of IGF2BP1 to the ETV6-RUNX1 fusion transcript which was also confirmed by us.To study the in vivo synergistic effect between ETV6-RUNX1 fusion protein and IGF2BP1, we used a murine bone marrow transplant model. The individual genes were overexpressed alone (IGF2BP1/ETV6-RUNX1) or together (IGF2BP1+ETV6-RUNX1) in separate groups of lethally irradiated mice (n=8 per group). In the group where both the genes were overexpressed together, there was clonal expansion and hypercellularity in the bone marrow. This was accompanied by an increase in the number of lineage negative cells (Lin-), progenitors including HSCs, LMPPs and c-kit+ cells which also showed high Ki67 positivity. The marrow hypercellularity led to extramedullary haematopoiesis which was seen as significant splenomegaly.In addition, analysis of the endogenous levels of Igf2bp1 in the bone marrow of the primary murine samples belonging to the ETV6-RUNX1 fusion protein overexpression group resulted in an increase in its levels, thus confirming our in vitro finding suggesting its induction by ETV6-RUNX1 fusion protein.RNA-Seq of IGF2BP1 KO cells identified enrichment of targets of the TNF alpha/NFκB signalling and K-Ras pathways hinting towards their dependency on IGF2BP1. The direct targets of IGF2BP1 were identified by RIP-Seq (RNA-Immunoprecipitation-Seq) analysis in Reh cell line. Numerous genes from the oncogenic signalling pathways including the TNF alpha/ NFκB signalling pathway were identified as IGF2BP1 targets. We validated some overexpressed genes from the TNF alpha/NFκB signalling and PI3K pathway in primary patient samples. We found significant overexpression of some of the genes (IL6ST, NFAT5, CDK6, MDM2, CCND1, NGFR) belonging to these pathways in the ETV6-RUNX1 positive group (n=39) compared to the negative cohort (n=111) as well as MACS sorted CD19+ B-cells (n=5). The decrease in the ETV6-RUNX1 transcript levels after downregulation of IGF2BP1 and overlap between the oncogenic pathways clearly shows an interdependency between the two genes.Overall, our results suggest a potential feedback mechanism between ETV6-RUNX1 fusion protein and IGF2BP1 in the pathogenesis of leukemia development and IGF2BP1 can be utilised as an ideal therapeutic target for this particular subtype. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Pre-Clinical Evaluation of Novel L-Asparaginase Mutants for the Treatment of Acute Lymphoblastic Leukemia

IntroductionAcute Lymphoblastic Leukemia (ALL) accounts for 20% of all hematological malignancies. L-Asparaginase has been a mainstay of ALL for the last 6 decades and is also included in the WHO list of essential medicines for ALL. Escherichia coli L-asparaginase (EcA) was the first asparaginase to be approved for clinical use. However being isolated from bacteria, EcA has many side-effects which in turn affects the tolerability and efficacy of the drug. EcA administration may cause strong immunogenic and hypersensitive reactions in the patients, necessitating withdrawal of the drug. Sensitive individuals react to repeated EcA administration with formation of anti-drug antibodies (ADAs) that bind to and inactivate the enzyme leading to inadequate plasma levels of EcA. Another serious drawback of EcA is the glutaminase activity which leads to neurotoxicity. Other side effects include hepatotoxicity, thromboembolism and pancreatitis. Although a number of attempts have been made to alleviate these problems by rational protein engineering, the optimization of therapy with EcA for ALL patients still remains a challenge. In an attempt to deal with these problems, we created several EcA mutants. On the basis of their activity, stability and antigenicity we short-listed four EcA mutants (Mutant A, B, C and D) having favourable properties for further development.MethodsWe identified and mutated several B-cell epitopes and amino acid residues at the EcA interface that are responsible for activity, stability and antigenicity. Enzyme activity was measured at 37 oC (optimum temperature for EcA). Glutaminase activity of the mutants was measured and compared to the wild type EcA. The cytotoxicity of the EcA variants was verified in ALL sensitive REH cell lines by performing MTT assay after 24 h incubation. Further the antigenicity of the mutants was assessed by performing indirect ELISA where the binding of the mutants to the commercially available l-asparaginase antibody was analysed. Further, in vivo immunogenicity was evaluated by immunizing Balc C mice with primary and booster doses of EcA mutants over 66 days followed by the measurement of IgG and IgM titers. In addition, the binding of wild-type EcA and mutants to pre-existing anti-asparaginase antibodies in serum isolated from primary and relapsed ALL patients receiving asparaginase therapy was studied by indirect ELISA. Pharmacokinetics of the mutants was evaluated in female Balb C mice by plotting the asparaginase activity-time curve till 24 h following administration of a single i.v. dose of 50 IU/kg and compared with the wildtype. Finally the safety of the EcA mutants was determined by performing single-dose acute toxicity study at 3 dose levels in Balb C mice.ResultsAt 37 oC, we did not find any significant difference in asparaginase activity of any EcA variant with the wild-type. All four variants showed markedly reduced glutaminase activity as compared to wild-type EcA (P<0.05). In MTT assay Mutant D showed 34.02%, Mutant B (32.4%), Mutant C (31.4%), Mutant A (24.22%), and wild type EcA (24.37%) reduction in REH cell viability in comparison to untreated cells. Binding to commercially available anti-asparaginase antibody was 49.09%, 32.63%, 27.43% less for Mutant D, Mutant B and Mutant C respectively compared to wild type EcA. Mice immunized with Mutant D showed 5-fold lower titres of IgG and 4-fold lower titres of IgM in comparison to wild type. Similarly, when compared to wild type, mice immunized with Mutant C showed 2.5-fold lower titres of IgG and 3.5-fold lower titres of IgM. At the same time Mutants B, C and D showed 2-3 fold less binding to pre-existing anti-asparaginase antibodies in samples collected from primary ALL patients undergoing asparaginase therapy. Similarly mutants B, C and D showed approximately 2-fold less binding to pre-existing anti-asparaginase antibodies in samples collected from relapsed ALL patients. Pharmacokinetic profiling showed that half life of Mutant A (267.28 ± 9.74), Mutant B (213.29 ± 6.53) and Mutant D (273.83 ± 35.45) was significantly longer than the wild type (102.17 ± 7.7). In acute toxicity study, we did not observe any significant toxicity of the mutants over the wildtype EcA. The findings are summarized in the figure.ConclusionConsidering the immunogenicity, antigenicity and pharmacokinetics, mutant D emerged as a potent drug candidate for further development in the treatment of ALL. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Britannin, a sesquiterpene lactone induces ROS-dependent apoptosis in NALM-6, REH, and JURKAT cell lines and produces a synergistic effect with vincristine.

Britannin, a Sesquiterpene Lactone isolated from Inula aucheriana, has recently gained attraction in the therapeutic fields due to its anti-tumor properties. This study was designed to evaluate the effect of this agent on Acute Lymphoblastic Leukemia (ALL) cell lines, either as a monotherapy or in combination with Vincristine (VCR). To determine the anti-leukemic effects of Britannin on ALL-derived cell lines and suggest a mechanism of action for the agent, we used MTT assay, Annexin-V/PI staining, ROS assay, and real-time PCR analysis. Moreover, by using a combination index (CI), we evaluated the synergistic effect of Britannin on Vincristine. We found that unlike normal Peripheral Blood Mononuclear Cells (PBMCs) and L929 cells, Britannin reduced the viability of NALM-6, REH, and JURKAT cells. Among tested cells, NALM-6 cells had the highest sensitivity to Britannin, and this agent was able to induce p21/p27-mediated G1 cell cycle arrest and Reactive Oxygen Specious (ROS)-mediated apoptotic cell death in this cell line. When NALM-6 cells were treated with Nacetyl-L-Cysteine (NAC), a scavenger of ROS, Britannin could induce neither apoptosis nor reduce the survival of the cells suggesting that the cytotoxic effect of Britannin is induced through ROS-dependent manner. Moreover, we found that a low dose of Britannin enhanced the effect of Vincristine in NALM-6 cells by inducing apoptotic cell death via altering the expression of apoptotic-related genes. Overall, our results proposed a mechanism for the cytotoxic effect of Britannin, either as a single agent or in combination with Vincristine, in NALM-6 cells.