The Effect of Asparaginase Conjugated with Carboxymethyl Dextran on Apoptosis and Autophagy in the NALM-6 Cell Line

Abstract

Background: Acute lymphoblastic leukemia (ALL) is classified as a malignant disorder. L-asparaginase has several adverse effects and low serum stability as a chemotherapy agent for ALL treatment. Our previous study demonstrated an improvement in the biochemical properties of chemically modified L-asparaginase with carboxymethyl dextran. Afterwards, this study was conducted to confirm the potential application of these findings in the NALM-6 cell line. Methods and Results: In this experimental study, the MTT assay was used to determine the effect of modified L-asparaginase, on the viability of the NALM-6 cell line. Flow cytometry and real-time RT-PCR techniques were employed to assess cell apoptosis and changes in the expression of the ATG2B and LC3-II genes. After 48 hours of treatment, conjugated L-asparaginase decreased the viability of the NALM-6 cell line, more than those of native L-asparaginase (P=0.01). Flow cytometry analysis revealed that modified L-asparaginase, increasesapoptosis compared to the control sample at all times (after 24 hours P<0.01, 48 hours P<0.01 and 72 hours P=0.03). This increase was more than which, the native enzyme caused. Additionally, quantitative RT-PCR analysis revealed that both enzymes increased LC3-II gene expression after 24 hours (P<0.01) while the native enzyme caused the increase more than the modified one (P=0.02). A significant increase in ATG2B expression was observed only after 24 hours of treatment with the native enzyme (P<0.01). Conclusions: This chemical modification induces apoptosis more, and stimulates the autophagy less than the native enzyme, and leads the cells to death instead of resistance to treatment.