Abstract

BACKGROUND: Glucocorticoids are important components of a number of chemotherapeutic regimens used to treat pediatric acute lymphoblastic leukemia (ALL). A primary cause of treatment failure of ALL is acquired resistance to glucocorticoids. Recently, traditional Chinese medicines were effectively used to treat solid tumors. Thus, the aim of this study was to investigate whether Huai Qi Huang (HQH), a traditional Chinese medicine, increased the efficacy of glucocorticoids in the treatment of ALL, and if so, to determine the underlying mechanism.

MATERIAL AND METHODS: Various concentrations of HQH were used to treat Jurkat and Nalm-6 cells for 24 to 72 hours. Subsequently, cells were co-treated with HQH and the glucocorticoid receptor agonist, dexamethasone (DEX), or a MEK inhibitor (PD98059) to verify the synergistic effects on apoptosis in Jurkat and Nalm-6 cells for 24 hours. Cell Counting Kit-8 assay and flow cytometry were used to measure cell viability and apoptosis, respectively. Protein and mRNA expression levels were assessed using western blotting and quantitative polymerase chain reaction.

RESULTS: The results revealed that cell survival was reduced and apoptosis was increased as the HQH concentration was increased, and this was accompanied with increases in the levels of BAX, cleaved-caspase-3 and glucocorticoid receptor α (GRα) and decreases in the levels of Bcl-2 and phospho-ERK (pERK). Glucocorticoid receptor β (GRβ) and total ERK (t-ERK) had no significant changes. Combined treatment with HQH and DEX or PD98059 increased apoptosis in Jurkat and Nalm-6 cells, and concurrently increased BAX, cleaved-caspase-3, GILZ, NFKBIA, and GRα and decreased Bcl-2 and pERK.

CONCLUSIONS: HQH enhanced the sensitivity of ALL cells to glucocorticoids by increasing the expression of GRα and inhibiting the MEK/ERK pathway, thus providing a rational foundation for the treatment of ALL with HQH.

Keywords: Apoptosis, MAP Kinase Kinase Kinases, Medicine, Chinese Traditional, Precursor Cell Lymphoblastic Leukemia-Lymphoma, Receptors, Glucocorticoid, Antineoplastic Combined Chemotherapy Protocols, Dexamethasone, Drug Synergism, Drugs, Chinese Herbal, Gene Expression Regulation, Leukemic, Jurkat Cells, Up-Regulation