Arsenic trioxide reduces chemo-resistance to 5-fluorouracil and cisplatin in HBx-HepG2 cells via complex mechanisms

Abstract

BackgroundMultidrug 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 (As2O3) on the hypoxia-induced chemo-resistance to 5-FU or cisplatin and explored its underlying mechanism in the HBx-HepG2 cells.MethodsMTT 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.ResultsOur 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 As2O3 at a non-cytotoxic concentration re-sensitized the hypoxia (1 % O2)-induced chemo-resistance to 5-FU and cisplatin in HBx-HepG2 cells. As2O3 pretreatment also prevented MMP reduction and G0/G1 arrest induced by hypoxia. Meanwhile, As2O3 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, As2O3 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.ConclusionsOur results may suggest that As2O3 re-sensitizes hypoxia-induced chemo-resistance in HBx-HepG2 via complex pathways, and As2O3 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.

Cystatin F involvement in adenosine A2A receptor-mediated neuroinflammation in BV2 microglial cells

“…The culture medium was removed and BV2 microglial cells were washed twice with glucose-free DMEM (Invitrogen). BV2 microglial cells were then switched from a normal feeding medium to a low glucose DMEM/F12medium (1 g/L) in an hypoxia incubator (3% O 2 , 5% CO 2 , 92% N 2 ) for 4 h, 8 h and 12 h 35 , 36 . The cell viability was assessed by a tetrazolium salt (WST-8)-based colorimetric assay in the Cell Counting Kit 8 (CCK-8; Dojindo, Kumamoto, Japan) 34 .…”

Mechanisms of Anticancer Drug Resistance in Hepatoblastoma

“…Regarding MOC-6, several studies have demonstrated tumor progression associated with high oxygen consumption and lower blood supply in tumor microenvironment, and that hypoxia enhances resistance to antitumor drugs. Thus, under hypoxia, HepG2 cells were more resistant to cisplatin than under normal conditions [42], which could be due, at least in part, to the up-regulation of the ABC pumps induced by hypoxia that would reduce intracellular cisplatin concentration [43]. ADAM17 is a transmembrane metalloproteinase found overexpressed in a variety of human tumors.…”

5-(Furan-2-yl)-4-(3,4,5-trimethoxyphenyl)-3H-1,2-dithiol-3- one oxime (6f), a new synthetic compound, causes human fibrosarcoma HT-1080 cell apoptosis by disrupting tubulin polymerisation and inducing G2/M arrest

“…Mitochondria is involved in cell apoptosis and MMP reflects the function of mitochondria (21). To determine whether 6f treated cells were truly undergoing apoptotic death, we assessed the changes of MMP in HT-1080 cells using Rhodamine staining and flow cytometry.…”