Targeting Chronic Myelogenous Leukemia With Imatinib And Glycyrrhizic Acid Combination Therapy

Abstract

Chronic myelogenous leukemia (CML) is a myeloproliferative neoplasm characterized by enhanced proliferation of granulocytes and their progenitor cells. An estimated 8,990 new cases of CML were diagnosed in 2019 and the prevalence of CML has been on the rise since the discovery of tyrosine kinase inhibitors (TKIs) in 2001. Imatinib (IMT), the first TKI approved for clinical use, is the gold standard for CML treatment, although rising resistance often require patients to switch TKI therapy at least once. Glycyrrhizic acid (GA) is a versatile drug due to its numerous reported therapeutic properties. Anti-tumor properties of GA indicate its use as a chemotherapeutic agent, and previous data from our lab has found apoptosis-inducing effects of GA in CML cell lines. We hypothesize that an IMT + GA combinational therapy would allow for better targeting of TKI-sensitive and TKI-resistant forms of chronic myelogenous leukemia. In the current study we examine the efficacy of combined IMT and GA therapy on chronic myelogenous leukemia cell lines. Cell proliferation and viability post-treatment were determined using Trypan Blue exclusion and MTT assay. Induction of apoptosis post-treatment was examined using Annexin V-FITC assay and Western Blot analysis. The protective effect of hyaluronic acid (HA) against treatment was determined using MTT assay. Proliferation and viability of CML cell lines was negatively correlated with IMT + GA cotreatment in a dose-related manner. The expected IMT-induced apoptosis of CML cells was further enhanced when GA was added to treatment at a concentration of 2.0 mM. At these concentrations of GA in combination with IMT, enhanced PARP cleavage compared to control. No protective effect against IMT + GA treatment was found with the addition of exogenous HA. Together these data show that chemotherapy consisting of imatinib and glycyrrhizic acid may be a novel method of treatment for CML. Furthermore, we began to investigate the mechanism of action of GA in CML therapy. Changes in gene expression patterns, following GA treatment, of genes involved with the synthesis and cleavage of HA and genes involved in the SUMOylation pathway were examined using RT-qPCR. Significant changes were seen in the genes related to HA modulation, although no significant changes were seen in genes related to SUMOylation. Further examination is required to elucidate the mechanism of action of GA in the therapy of CML.