Differential mechanisms of asparaginase resistance in B-type acute lymphoblastic leukemia and malignant natural killer cell lines

An acute lymphoblastic leukemia cell-based preclinical assay revealed functional differences between commercial brands of L-asparaginase administered in Colombia

BACKGROUND

L-asparaginase (L-ASNase) is an essential component of chemotherapy strategies due to its differential action between normal and leukemic cells. Recently, concerns about the efficiency of commercial formulations administered in developing countries have been reported, and available methods have limitations for directly determining the quality of the formulation of the medications.

PROCEDURE

We developed a cell-based protocol to analyze the activity of different L-ASNase formulations used in Colombia to induce apoptosis of the NALM-6 cell line after 24, 48, and 72 hours, using flow cytometry. Then we compared results and determined the statistically significant differences.

RESULTS

Three statistically different groups, ranging from full to no activity against leukemic cells, using 0.05, 0.5, and 5.0 IU/ml concentrations, were identified. Group 1 (asparaginase codified [ASA]2-4) exhibited very low to no activity against B-cell acute lymphoblastic leukemia (B-ALL) cells. Group 2 (ASA6) exhibited intermediate-level activity, and group 3 (ASA1 and ASA5) exhibited high activity.

CONCLUSIONS

Differences found between the therapeutic formulations of L-ASNase distributed in Colombia raise concerns about the quality of the treatment administered to patients in low- and middle-income countries. Therefore, we recommend a preclinical evaluation of formulations of L-ASNase in order to prevent therapeutical impacts on the outcome of ALL patients.

Construction of three-gene-based prognostic signature and analysis of immune cells infiltration in children and young adults with B-acute lymphoblastic leukemia

Background

Although B‐acute lymphoblastic leukemia (B‐ALL) patients' survival has been improved dramatically, some cases still relapse. This study aimed to explore the prognosis‐related novel differentially expressed genes (DEGs) for predicting the overall survival (OS) of children and young adults (CAYAs) with B‐ALL and analyze the immune‐related factors contributing to poor prognosis.

Methods

GSE48558 and GSE79533 from Gene Expression Omnibus (GEO) and clinical sample information and mRNA‐seq from Therapeutically Applicable Research to Generate Effective Treatments (TARGET) database were retrieved. Prognosis‐related key genes were enrolled to build a Cox proportional model using multivariate Cox regression. Five‐year OS of patients, clinical characteristic relevance and clinical independence were assessed based on the model. The mRNA levels of prognosis‐related genes were validated in our samples and the difference of immune cells composition between high‐risk and low‐risk patients were compared.

Results

One hundred and twelve DEGs between normal B cells and B‐ALL cells were identified based on GSE datasets. They were mainly participated in protein binding and HIF‐1 signaling pathway. One hundred and eighty‐nine clinical samples were enrolled in the study, both Kaplan–Meier (KM) analysis and univariate Cox regression analysis showed that CYBB, BCL2A1, IFI30, and EFNB1 were associated with prognosis, CYBB, BCL2A1, and EFNB1 were used to construct prognostic risk model. Moreover, compared to clinical indicators, the three‐gene signature was an independent prognostic factor for CAYAs with B‐ALL. Finally, the mRNA levels of CYBB, BCL2A1, and EFNB1 were significantly lower in B‐ALL group as compared to controls. The high‐risk group had a significantly higher percentage of infiltrated immune cells.

Conclusion

We constructed a novel three‐gene signature with independent prognostic factor for predicting 5‐year OS of CAYAs with B‐ALL. Additionally, we discovered the difference of immune cells composition between high‐risk and low‐risk groups. This study may help to customize individual treatment and improve prognosis of CAYAs with B‐ALL.

Resistance Mechanisms in Pediatric B-Cell Acute Lymphoblastic Leukemia

Despite the rapid development of medicine, even nowadays, acute lymphoblastic leukemia (ALL) is still a problem for pediatric clinicians. Modern medicine has reached a limit of curability even though the recovery rate exceeds 90%. Relapse occurs in around 20% of treated patients and, regrettably, 10% of diagnosed ALL patients are still incurable. In this article, we would like to focus on the treatment resistance and disease relapse of patients with B-cell leukemia in the context of prognostic factors of ALL. We demonstrate the mechanisms of the resistance to steroid therapy and Tyrosine Kinase Inhibitors and assess the impact of genetic factors on the treatment resistance, especially TCF3::HLF translocation. We compare therapeutic protocols and decipher how cancer cells become resistant to innovative treatments—including CAR-T-cell therapies and monoclonal antibodies. The comparisons made in our article help to bring closer the main factors of resistance in hematologic malignancies in the context of ALL.

ALL blasts drive primary mesenchymal stromal cells to increase asparagine availability during asparaginase treatment

Mechanisms underlying the resistance of acute lymphoblastic leukemia (ALL) blasts to l-asparaginase are still incompletely known. Here we demonstrate that human primary bone marrow mesenchymal stromal cells (MSCs) successfully adapt to l-asparaginase and markedly protect leukemic blasts from the enzyme-dependent cytotoxicity through an amino acid trade-off. ALL blasts synthesize and secrete glutamine, thus increasing extracellular glutamine availability for stromal cells. In turn, MSCs use glutamine, either synthesized through glutamine synthetase (GS) or imported, to produce asparagine, which is then extruded to sustain asparagine-auxotroph leukemic cells. GS inhibition prevents mesenchymal cells adaptation to l-asparaginase, lowers glutamine secretion by ALL blasts, and markedly hinders the protection exerted by MSCs on leukemic cells. The pro-survival amino acid exchange is hindered by the inhibition or silencing of the asparagine efflux transporter SNAT5, which is induced in mesenchymal cells by ALL blasts. Consistently, primary MSCs from ALL patients express higher levels of SNAT5 (P < .05), secrete more asparagine (P < .05), and protect leukemic blasts (P < .05) better than MSCs isolated from healthy donors. In conclusion, ALL blasts arrange a pro-leukemic amino acid trade-off with bone marrow mesenchymal cells, which depends on GS and SNAT5 and promotes leukemic cell survival during l-asparaginase treatment.

Amino Acid Depletion Therapies: Starving Cancer Cells to Death

Targeting tumor cell metabolism is an attractive form of therapy, as it may enhance treatment response in therapy resistant cancers as well as mitigate treatment-related toxicities by reducing the need for genotoxic agents. To meet their increased demand for biomass accumulation and energy production and to maintain redox homeostasis, tumor cells undergo profound changes in their metabolism. In addition to the diversion of glucose metabolism, this is achieved by upregulation of amino acid metabolism. Interfering with amino acid availability can be selectively lethal to tumor cells and has proven to be a cancer specific Achilles' heel. Here we review the biology behind such cancer specific amino acid dependencies and discuss how these vulnerabilities can be exploited to improve cancer therapies.

A comprehensive review on microbial l-asparaginase: Bioprocessing, characterization, and industrial applications

l-Asparaginase (E.C.3.5.1.1.) is a vital enzyme that hydrolyzes l-asparagine to l-aspartic acid and ammonia. This property of l-asparaginase inhibits the protein synthesis in cancer cells, making l-asparaginase a mainstay of pediatric chemotherapy practices to treat acute lymphoblastic leukemia (ALL) patients. l-Asparaginase is also recognized as one of the important food processing agent. The removal of asparagine by l-asparaginase leads to the reduction of acrylamide formation in fried food items. l-Asparaginase is produced by various organisms including animals, plants, and microorganisms, however, only microorganisms that produce a substantial amount of this enzyme are of commercial significance. The commercial l-asparaginase for healthcare applications is chiefly derived from Escherichia coli and Erwinia chrysanthemi. A high rate of hypersensitivity and adverse reactions limits the long-term clinical use of l-asparaginase. Present review provides thorough information on microbial l-asparaginase bioprocess optimization including submerged fermentation and solid-state fermentation for l-asparaginase production, downstream purification, its characterization, and issues related to the clinical application including toxicity and hypersensitivity. Here, we have highlighted the bioprocess techniques that can produce improved and economically viable yields of l-asparaginase from promising microbial sources in the current scenario where there is an urgent need for alternate l-asparaginase with less adverse effects.

The Metabolic Profiles in Hematological Malignancies

Leukemia is one of the most aggressive hematological malignancies. Leukemia stem cells account for the poor prognosis and relapse of the disease. Decades of investigations have been performed to figure out how to eradicate the leukemia stem cells. It has also been known that cancer cells especially solid cancer cells use energy differently than most of the cell types. The same thing happens to leukemia. Since there are metabolic differences between the hematopoietic stem cells and their immediate descendants, we aim at manipulating the energy sources with which that could have an effect on leukemia stem cells while sparing the normal blood cells. In this review we summarize the metabolic characteristics of distinct leukemias such as acute myeloid leukemia, chronic myeloid leukemia, T cell lymphoblastic leukemia, B-cell lymphoblastic leukemia, chronic lymphocytic leukemia and other leukemia associated hematological malignancies such as multiple myeloma and myelodysplastic syndrome. A better understanding of the metabolic profiles in distinct leukemias might provide novel perspectives and shed light on novel metabolic targeting strategies towards the clinical treatment of leukemias.

Gene expression of ASNS, LGMN and CTSB is elevated in a subgroup of childhood BCP-ALL with PAX5 deletion

Resistance to L-asparaginase (L-asp) is a major contributor to poor treatment outcomes of several subtypes of childhood B cell precursor acute lymphoblastic leukemia (BCP-ALL). Asparagine synthetase (ASNS), legumain (LGMN) and cathepsin B (CTSB) serve a key role in L-asp resistance. The association between genetic subtypes of BCP-ALL and the expression of ASNS, LGMN and CTSB may elucidate the mechanisms of treatment failure. Bone marrow samples of 52 children newly diagnosed with BCP-ALL were screened for major genetic abnormalities and ASNS, LGMN and CTSB gene expression levels. The cohort was further divided into groups corresponding to the key genetic aberrations occurring in BCP-ALL: Breakpoint cluster region and Abelson murine leukemia viral oncogene homolog 1 fusion; hyperdiploidy, hypodiploidy, ETS variant 6 and runt-related transcription factor 1 fusion and other BCP-ALL with no primary genetic aberration identified. A subgroup analysis based on the differences in copy number variations demonstrated a significant increase of ASNS, LGMN and CTSB median expression in other BCP-ALL cases with paired box 5 (PAX5) deletion (P=0.0117; P=0.0036; P<0.0001, respectively) compared with those with wild-type PAX5. Patients with high ASNS expression exhibited longer relapse-free survival (RFS) compared with those with low ASNS levels (P=0.0315; HR, 0.19; 95% CI, 0.04-0.86); the 5-year RFS for patients in the high ASNS expression group was 90.15% (95% CI, 87.90-92.40%). Despite the impact on ASNS, LGMN and CTSB expression, PAX5 deletion did not influence RFS in the other BCP-ALL group (P=0.6839). Therefore, the results of the present study revealed high levels of ASNS, LGMN and CTSB expression in the other BCP-ALL group with concomitant PAX5 deletion and no subsequent deterioration in 5-year RFS. High ASNS expression level, as a single factor, was strongly associated with an improved outcome.

Amino acid metabolism in hematologic malignancies and the era of targeted therapy

Tumor cells rewire metabolic pathways to adapt to their increased nutritional demands for energy, reducing equivalents, and cellular biosynthesis. Alternations in amino acid metabolism are 1 modality for satisfying those demands. Amino acids are not only components of proteins but also intermediate metabolites fueling multiple biosynthetic pathways. Amino acid-depletion therapies target amino acid uptake and catabolism using heterologous enzymes or recombinant or engineered human enzymes. Notably, such therapies have minimal effect on normal cells due to their lower demand for amino acids compared with tumor cells and their ability to synthesize the targeted amino acids under conditions of nutrient stress. Here, we review novel aspects of amino acid metabolism in hematologic malignancies and deprivation strategies, focusing on 4 key amino acids: arginine, asparagine, glutamine, and cysteine. We also present the roles of amino acid metabolism in the immunosuppressive tumor microenvironment and in drug resistance. This summary also offers an argument for the reclassification of amino acid-depleting enzymes as targeted therapeutic agents.

KLF5 controls glutathione metabolism to suppress p190-BCR-ABL+ B-cell lymphoblastic leukemia

High-risk B-cell acute lymphoblastic leukemia (B-ALL) remains a therapeutic challenge despite advances in the use of tyrosine kinase inhibitors and chimeric-antigen-receptor engineered T cells. Lymphoblastic-leukemia precursors are highly sensitive to oxidative stress. KLF5 is a member of the Krüppel-like family of transcription factors. KLF5 expression is repressed in B-ALL, including BCR-ABL1+ B-ALL. Here, we demonstrate that forced expression of KLF5 in B-ALL cells bypasses the imatinib resistance which is not associated with mutations of BCR-ABL. Expression of Klf5 impaired leukemogenic activity of BCR-ABL1+ B-cell precursors in vitro and in vivo. The complete genetic loss of Klf5 reduced oxidative stress, increased regeneration of reduced glutathione and decreased apoptosis of leukemic precursors. Klf5 regulation of glutathione levels was mediated by its regulation of glutathione-S-transferase Mu 1 (Gstm1), an important regulator of glutathione-mediated detoxification and protein glutathionylation. Expression of Klf5 or the direct Klf5 target gene Gstm1 inhibited clonogenic activity of Klf5^∆/∆ leukemic B-cell precursors and unveiled a Klf5-dependent regulatory loop in glutamine-dependent glutathione metabolism. In summary, we describe a novel mechanism of Klf5 B-ALL suppressor activity through its direct role on the metabolism of antioxidant glutathione levels, a crucial positive regulator of leukemic precursor survival.

Drug-induced amino acid deprivation as strategy for cancer therapy

Cancer is caused by uncontrollable growth of neoplastic cells, leading to invasion of adjacent and distant tissues resulting in death. Cancer cells have specific nutrient(s) auxotrophy and have a much higher nutrient demand compared to normal tissues. Therefore, different metabolic inhibitors or nutrient-depleting enzymes have been tested for their anti-cancer activities. We review recent available laboratory and clinical data on using various specific amino acid metabolic pathways inhibitors in treating cancers. Our focus is on glutamine, asparagine, and arginine starvation. These three amino acids are chosen due to their better scientific evidence compared to other related approaches in cancer treatment. Amino acid-specific depleting enzymes have been adopted in different standard chemotherapy protocols. Glutamine starvation by glutaminase inhibitior, transporter inhibitor, or glutamine depletion has shown to have significant anti-cancer effect in pre-clinical studies. Currently, glutaminase inhibitor is under clinical trial for testing anti-cancer efficacy. Clinical data suggests that asparagine depletion is effective in treating hematologic malignancies even as a single agent. On the other hand, arginine depletion has lower toxicity profile and can effectively reduce the level of pro-cancer biochemicals in patients as shown by ours and others’ data. This supports the clinical use of arginine depletion as anti-cancer therapy but its exact efficacy in various cancers requires further investigation. However, clinical application of these enzymes is usually hindered by common problems including allergy to these foreign proteins, off-target cytotoxicity, short half-life and rapidly emerging chemoresistance. There have been efforts to overcome these problems by modifying the drugs in different ways to circumvent these hindrance such as (1) isolate human native enzymes to reduce allergy, (2) isolate enzyme isoforms with higher specificities and efficiencies, (3) pegylate the enzymes to reduce allergy and prolong the half-lives, and (4) design drug combinations protocols to enhance the efficacy of chemotherapy by drug synergy and minimizing resistance. These improvements can potentially lead to the development of more effective anti-cancer treatment with less adverse effects and higher therapeutic efficacy.

Pharmacogenomics in pediatric acute lymphoblastic leukemia: promises and limitations

Despite the significant advances achieved in pediatric acute lymphocytic leukemia (ALL) treatment, adverse side effects of drugs remain a challenging issue. Numerous ALL pharmacogenomic studies have been conducted to elucidate the predisposing genetic factors for their development. Plausible pharmacogenomic data are available for the osteonecrosis associated with glucocorticoids, the neurotoxicity associated with vincristine and the cardiotoxicity related to anthracyclines. However, these data have not been fully translated into the clinic due to several limitations, most importantly the lack of reliable evidence. The most robust pharmacogenomics data are those for thiopurines and methotrexate use, with evidence-based preemptive testing recommendations for the former. Pharmacogenomics has a significant potential utility in pediatric ALL treatment regimens. In this review, gaps and limitations in this field are emphasized, which may provide a useful guide for future research design.

Metabolic reprogramming of glioblastoma cells by L-asparaginase sensitizes for apoptosis in vitro and in vivo

Cancer cells display a variety of global metabolic changes, which aside from the glycolytic pathway largely involve amino acid metabolism. To ensure aggressive growth, tumor cells highly depend on amino acids, most notably due to their pivotal need of protein synthesis. In this study, we assessed the overall hypothesis that depletion of asparagine by E. coli-derived L-asparaginase might be a novel means for the therapy of one of the most recalcitrant neoplasms and for which no efficient treatment currently exists - glioblastoma (WHO grade IV). Our results suggest that certain glioma cell cultures are particularly susceptible to inhibition of proliferation by L-asparaginase, while others display a more resistant phenotype. In sensitive cells, L-asparaginase induces apoptosis with dissipation of mitochondrial membrane potential and activation of effector caspases. L-asparaginase-mediated apoptosis was accompanied by modulation of pro- and anti-apoptotic Bcl-2 family members, including Noxa, Mcl-1 and the deubiquitinase Usp9X. Given the impact of L-asparaginase on these molecules, we found that L-asparaginase potently overcomes resistance to both intrinsic apoptosis induced by the Bcl-2/Bcl-xL inhibitor, ABT263, and extrinsic apoptosis mediated by TRAIL even in glioma cells that are resistant towards L-asparaginase single treatment. RNA interference studies showed that Usp9X, Mcl-1, Noxa and Bax/Bak are involved in ABT263/L-asparaginase-mediated cell death. In vivo, combined treatment with ABT263 and L-asparaginase led to an enhanced reduction of tumor growth when compared to each reagent alone without induction of toxicity. These observations suggest that L-asparaginase might be useful for the treatment of malignant glial neoplasms.

[Expression of asparagine synthetase in relapsed or refractory extranodal NK/T cell lymphoma]

OBJECTIVE

To detect the expression level of asparagine synthetase (ASNS) in patients with relapsed or refractory extranodal NK/T cell lymphoma and explore its clinical significance.

METHODS

Ten patients with relapsed or refractory extranodal NK/T cell lymphoma admitted in our department from January, 2013 to January, 2016 were analyzed. The diagnoses were confirmed by pathological and immunohistochemical examination following failed chemotherapies in all cases. Branched DNA-liquidchip technique (bDNA-LCT) was used for detecting ASNS mRNA expression in paraffin-embedded tissue sections in the 10 cases of relapsed or refractory extranodal NK/T cell lymphoma and in 5 cases of chronic rhinitis. The correlations were analyzed between ASNS expression and the clinicopathological features and outcomes of the patients with failed chemotherapy regimens containing asparaginasum.

RESULTS

Six out of the 10 patients with relapsed or refractory extranodal NK/T cell lymphoma died due to diseaseprogression. The expression level of ASNS was significantly higher in the lymphoma tissues than in tissue specimens of chronic rhinitis (P<0.05). The expression level of ASNS was associated with the International Prognostic Index (P=0.023) in patients with relapsed or refractory extranodal NK/T cell lymphoma, and Kaplan-Meier curve showed that a high ASNS expression was correlated with a reduced overall survival and progression-free survival of the patients.

CONCLUSION

Asparaginasum-based chemotherapy regimens are recommended for treatment of relapsed or refractory extranodal NK/T cell lymphoma with low ASNS expressions.

[Expression of asparagine synthetase in relapsed or refractory extranodal NK/T cell lymphoma]

OBJECTIVE

To detect the expression level of asparagine synthetase (ASNS) in patients with relapsed or refractory extranodal NK/T cell lymphoma and explore its clinical significance.

METHODS

Ten patients with relapsed or refractory extranodal NK/T cell lymphoma admitted in our department from January, 2013 to January, 2016 were analyzed. The diagnoses were confirmed by pathological and immunohistochemical examination following failed chemotherapies in all cases. Branched DNA-liquidchip technique (bDNA-LCT) was used for detecting ASNS mRNA expression in paraffin-embedded tissue sections in the 10 cases of relapsed or refractory extranodal NK/T cell lymphoma and in 5 cases of chronic rhinitis. The correlations were analyzed between ASNS expression and the clinicopathological features and outcomes of the patients with failed chemotherapy regimens containing asparaginasum.

RESULTS

Six out of the 10 patients with relapsed or refractory extranodal NK/T cell lymphoma died due to diseaseprogression. The expression level of ASNS was significantly higher in the lymphoma tissues than in tissue specimens of chronic rhinitis (P<0.05). The expression level of ASNS was associated with the International Prognostic Index (P=0.023) in patients with relapsed or refractory extranodal NK/T cell lymphoma, and Kaplan-Meier curve showed that a high ASNS expression was correlated with a reduced overall survival and progression-free survival of the patients.

CONCLUSION

Asparaginasum-based chemotherapy regimens are recommended for treatment of relapsed or refractory extranodal NK/T cell lymphoma with low ASNS expressions.

A clinically attainable dose of L-asparaginase targets glutamine addiction in lymphoid cell lines

L-asparaginase (L-ASNase) is an important branch of chemotherapy for acute lymphoblastic leukemia (ALL) and some types of non-Hodgkin's lymphoma, including natural killer (NK)-cell lymphoma. Although it mediates hydrolysis of asparagine (Asn) and glutamine (Gln), which are variably required for cancer cell survival, the relative contribution of Asn and Gln depletion to the anti-tumor activity in therapeutic doses is unclear in ALL and malignant lymphoma. Here we demonstrate that L-ASNase exerts cytotoxicity through targeting the Gln addiction phenotype in lymphoid cell lines. A clinically attainable intermediate dose of L-ASNase induced massive apoptosis in ALL Jurkat and mantle cell lymphoma Jeko cell lines, while a low dose of L-ASNase effectively killed NK-cell lymphoma cells. In the lymphoid cell lines Jurkat and Jeco, deprivation of Gln but not Asn specifically suppressed cell growth and survival, and phenocopied the action of L-ASNase. L-ASNase treatment and Gln deprivation dramatically disrupted the refilling of the tricarboxylic acid (TCA) cycle by intracellular glutamate (Glu) and disturbed the mitochondrial integrity, which were alleviated by various anaplerotic TCA cycle intermediates, suggesting a direct contribution of glutaminase activity of L-ASNase. The action of L-ASNase differs between Jurkat cells and NK-cell lymphoma cells, according to their dependence on Gln and Asn. Furthermore, we observed that high expression of glutaminase GLS1 is associated with increased sensivity to L-ASNase in pediatric B lineage ALL. Our results redefine L-ASNase as a therapeutic agent targeting Gln addiction in certain lymphoid cells and offer an additional basis for predicting L-ASNase sensitivity and engineering selective L-ASNase derivatives for leukemia and lymphoma.

Mechanisms of tumour resistance against chemotherapeutic agents in veterinary oncology

Several classes of chemotherapy drugs are used as first line or adjuvant treatment of the majority of tumour types in veterinary oncology. However, some types of tumour are intrinsically resistant to several anti-cancer drugs, and others, while initially sensitive, acquire resistance during treatment. Chemotherapy often significantly prolongs survival or disease free interval, but is not curative. The exact mechanisms behind intrinsic and acquired chemotherapy resistance are unknown for most animal tumours, but there is increasing knowledge on the mechanisms of drug resistance in humans and a few reports on molecular changes in resistant canine tumours have emerged. In addition, approaches to overcome or prevent chemotherapy resistance are becoming available in humans and, given the overlaps in molecular alterations between human and animal tumours, these may also be relevant in veterinary oncology. This review provides an overview of the current state of research on general chemotherapy resistance mechanisms, including drug efflux, DNA repair, apoptosis evasion and tumour stem cells. The known resistance mechanisms in animal tumours and the potential of these findings for improving treatment efficacy in veterinary oncology are also explored.