Galbanic Acid Improves Accumulation and Toxicity of Arsenic Trioxide in MT-2 Cells

Abstract

Background: Galbanic acid (GBA) is a sesquiterpene coumarin with valuable pharmacological effects. Adult T-cell lymphoma (ATL) is an aggressive lymphoid malignancy with low survival rate. Although arsenic trioxide (ATO) is a standard therapeutic agent for ATL treatment, efficacy of chemotherapy is limited due to chemoresistance of cells. Objective: The present study was carried out to investigate whether GBA in combination with ATO would improve cytotoxicity against ATL cells. Methods: GBA was isolated from the roots of Ferula szowitsiana by column chromatography on silica gel. MT-2 cells were treated with 20 µM GBA + 4 µM ATO and viability was evaluated by alamarBlue assay. Cell cycle was analyzed by PI staining, while the activity of P-glycoprotein (P-gp) was evaluated by mitoxantrone efflux assay. To understand the molecular mechanisms of GBA effects, the expression of NF-κB (RelA), P53, CDK4, c-MYC, c-FLIPL and c-FLIPS was evaluated by real-time PCR. Results: Combinatorial use of GBA + ATO significantly reduced the viability of MT-2 cells, and induced cell cycle arrest in the sub-G1 phase. GBA improved mitoxantrone accumulation in cells, indicating that this agent has inhibitory effects on the functionality of P-gp efflux pump. Moreover, real-time PCR analysis revealed that GBA + ATO negatively regulated the expression of P53, CDK4, c-FLIPL and c-FLIPS. Conclusion: Due to the interesting effects of GBA on the accumulation and toxicity of ATO, combinatorial use of these agents could be considered as a new therapeutic approach for ATL treatment.

Comparing toxicity of galbanic acid, auraptene and umbelliprenin on adult T-cell leukaemia-lymphoma in normoxia and hypoxia

“…Time-and dose-dependent toxicity of GBA has been reported in human ovarian, lung and prostate carcinoma cells, and upregulation of caspase 9, downregulation of antiapoptotic protein BCL-xL and inhibition of androgen receptor signaling pathway have been introduced as mechanisms of its anticancer action (24)(25)(26). In addition, it has been demonstrated that GBA has the potential to improve the accumulation and efficacy of arsenic trioxide in ATL cells (27). The current study is the first report indicating low doses of GBA (10 and 20 µM) induced significant toxicity on ATL cells in hypoxia.…”