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CancerGenetics

• From L-Asparaginase Engineering to Precision Medicine: The Role of ASNS in Leukemic Cell Sensitivity

• mozhdeh Mahmoudabadi,¹ Mohammad Amin Noorollahian,^2,*
  1. M.Sc. Student in Industrial Microbiology, Islamic Azad University, Mashhad
  2. M.Sc. Student in Industrial Microbiology, Islamic Azad University, Mashhad
  
  
  
• Introduction: L-asparaginase is an important therapeutic enzyme used in the treatment of acute lymphoblastic leukemia (ALL), exerting its antileukemic effects by reducing extracellular asparagine availability and inducing metabolic stress in leukemic cells. However, glutaminase activity, immunogenicity, toxicity, limited stability, and short half-life remain important challenges in its therapeutic application. Microbial production, particularly using recombinant microorganisms, combined with protein engineering and targeted mutagenesis, provides opportunities to improve these properties. On the other hand, the response of leukemic cells to L-asparaginase depends on their capacity for asparagine synthesis and, consequently, on the status of the ASNS gene. Available evidence suggests that epigenetic regulation of ASNS, particularly promoter methylation, may be associated with L-asparaginase sensitivity and treatment outcome.
• Methods: In this narrative review, published evidence on microbial and recombinant production of L-asparaginase, protein engineering, and targeted mutagenesis, with a focus on engineered E. coli variants, was reviewed and compared with studies investigating the molecular and epigenetic regulation of ASNS in T-ALL. Studies addressing ASNS promoter methylation and allele-specific methylation were evaluated, with emphasis on their associations with the therapeutic properties of L-asparaginase, including reduced glutaminase activity and adverse effects, as well as leukemic cell response.
• Results: The reviewed evidence indicates that L-asparaginase engineering can overcome some limitations of the native enzyme. In one study, engineered L-asparaginase variants derived from E. coli showed a marked reduction in glutaminase activity compared with the wild-type enzyme, with approximately 24-fold lower glutaminase activity reported for some variants. These variants also demonstrated improved therapeutic properties, including increased half-life and antileukemic efficacy. In studies of ASNS, analysis of 22 T-ALL cell lines showed that increased ASNS methylation was associated with greater sensitivity to L-asparaginase. Analysis of 77 patient samples also demonstrated an association between ASNS methylation status and treatment outcome; in contrast, ASNS hypomethylation was associated with greater resistance to L-asparaginase and poorer outcome. These findings indicate that treatment response may be considered not only in terms of drug characteristics but also according to the molecular characteristics of the target leukemic cells.
• Conclusion: The findings suggest a two-pronged approach to improving L-asparaginase-based therapy: engineering the enzyme itself to produce a therapeutic agent with improved performance and identifying molecular characteristics of leukemic cells to predict treatment response. In this context, the epigenetic status of ASNS may serve as a potential biomarker for stratifying patients according to their likelihood of responding to L-asparaginase and support more informed treatment selection. However, current evidence is largely derived from laboratory studies, preclinical models, and cohorts limited to T-ALL, and further validation in larger populations and independent clinical studies is required to establish the clinical value of ASNS as a biomarker. Therefore, combining microbial and protein engineering of L-asparaginase with molecular stratification of patients represents a testable strategy for developing more precise and effective L-asparaginase-based therapies rather than an established clinical approach.
• Keywords: L-Asparaginase Protein Engineering ASNS Epigenetic Regulation Precision Medicine