Arsenic trioxide reduces chemo-resistance to 5-fluorouracil and cisplatin in HBx-HepG2 cells via complex mechanisms. Issue 1 (December 2015)

• Record Type: Journal Article
• Authors: Yu, Guifang; Chen, Xuezhu; Chen, Shudi; Ye, Weipeng; Hou, Kailian; Liang, Min
• Is Part Of: Cancer cell international. Volume 15:Issue 1(2015)
• Page Start: 1
• Page End: 12
• Publication Date: 2015-12
• Subjects: HBV -- HCC -- HBx-HepG2 -- 5-FU -- Cisplatin -- Chemo-resistance -- HIF-1α -- P-gp -- MRP1 -- LRP; Cytology -- Periodicals; 616.994
• DOI: 10.1186/s12935-015-0269-y
• Languages: English
• ISSNs: 1475-2867

Abstract

Abstract Background Multidrug resistance is one of the major reasons chemotherapy-based treatments failed in hepatitis B virus (HBV) related hepatocellular carcinoma (HCC). Hypoxia is generally associated with tumor chemo-resistance. The aim of the study was to investigate the effect of Arsenic trioxide (As2 O3 ) on the hypoxia-induced chemo-resistance to 5-FU or cisplatin and explored its underlying mechanism in the HBx-HepG2 cells. Methods MTT assay was used to examine the cell viability. Mitochondrial membrane potential (MMP) and cell cycle was examined by flow cytometry. qRT-PCR was employed to observe the mRNA expression level; and western blot assay was used to determine the protein expression level. Results Our results showed that transfection of HBx plasmid established the HBx-HepG2 cells expressing HBx, and the expression of HBx was confirmed by qRT-PCR and western blot. Exposure of HBx-HepG2 cells to hypoxia (5 % O2, 3 % O2, 1 % O2 ) for 48 h increased the chemo-resistance to 5-fluorouracil (5-FU) (50–1600 µM) and cisplatin (25–800 µM), reduced MMP, and caused the cell cycle arrest at G0 /G1 phase in a concentration-dependent manner. Hypoxia also concentration-dependently (5 % O2, 3 % O2, 1 % O2 ) reduced mRNA expression level of P-glycoprotein (P-gp), multidrug resistance protein (MRP1), lung resistance protein (LRP), and decreased the protein expression level of hypoxia-inducible factor-1α (HIF-1α), P-gp MRP1, and LRP. Following pretreatment with As2 O3 at a non-cytotoxic concentration re-sensitized the hypoxia (1 % O2 )-induced chemo-resistance to 5-FU and cisplatin in HBx-HepG2 cells. As2 O3 pretreatment also prevented MMP reduction and G0 /G1 arrest induced by hypoxia. Meanwhile, As2 O3 antagonized increase of HIF-1α protein induced by hypoxia, and it also suppresses the increase in expression levels of P-gp, MRP1, and LRP mRNA and proteins. In addition, As2 O3 in combination with 5-FU treatment caused up-regulation of DR5, caspase 3, caspase 8, and caspase 9, and down-regulation of BCL-2, but had no effect of DR4. Conclusions Our results may suggest that As2 O3 re-sensitizes hypoxia-induced chemo-resistance in HBx-HepG2 via complex pathways, and As2 O3 may be a potential agent that given in combination with other anti-drugs for the treatment of HBV related HCC, which is resistant to chemotherapy.