OBJECTIVES: Radiotherapy is one of the main therapies for colorectal cancer, but radioresistance often leads to radiotherapy failure. To improve the radioresistance, we explore the effect of oligomycin A, the H METHODS: The effects of different concentrations of oligomycin A on the survival rate and glycolysis of HT29 colorectal cancer cells at different time points were investigated via MTT and glycolysis assay. siRNA-PFK1 was synthesized in vitro and transfected into HT29 cells. The effects of oligomycin A on radiosensitivity of HT29 colorectal cancer cells were measured via MTT and colony formation assay. Western blotting was used to detect the effect of oligomycin A on the expression of glycolytic enzyme PFK1. We compared difference between the effects of siRNA-PFK1 group and oligomycin A combined with siRNA-PFK1 group on cell survival and glycolysis. After 4 Gy X-ray irradiation, the effects of cell survival and glycolysis between the siRNA-PFK1 group and the oligomycin A combined with siRNA-PFK1 group were compared. RESULTS: Compared with the 0 μmol/L oligomycin A group, the cell survival rate of HT29 cells treated with 4 μmol/L oligomycin A was significantly increased ( CONCLUSIONS Oligomycin A can promote the radioresistance of HT29 colorectal cancer cells, which may be related to up-regulation of the PFK1 expression and increase of cell glycolysis.
Cell Line, Tumor ; Colorectal Neoplasms/genetics* ; HT29 Cells ; Humans ; Oligomycins/pharmacology* ; Radiation Tolerance

OBJECTIVETo investigate the effect of hypoxia on HIF-1alpha activation in intestinal epithelial cells.

METHODSIntestinal epithelial cells were randomly divided into normal control group, hypoxia group and hypoxia plus oligomycin group (oligomycin group). In hypoxia group, the cells were exposed to hypoxia for 1, 2, 6, 12 and 24 h. In oligomycin group, the cells were treated with oligomycin in concentration of 5, 10, 20 and 40 microg/mL for 1 h prior to 6-hour hypoxic exposure. HIF-1alpha protein expression was assayed by western blot method. Nuclear translocation of HIF-1alpha was detected by immunofluorescence analysis.

RESULTSCompared with that in control group (0.08 +/- 0.07), HIF-1alpha protein expression in hypoxia group increased significantly at 1 h (0.52 +/- 0.30, P < 0.05), and reached the peak value (2.37 +/- 1.08, P < 0.05) at 6 h. Nuclear translocation of HIF-1alpha was also induced by hypoxia. HIF-1alpha protein expression in oligomycin group in the concentration of 5, 10, 20 and 40 microg/mL of oligomycin was 1.62 +/- 0.96, 1.48 +/- 0.56, 1.08 +/- 0.36 and 0.58 +/- 0.11 respectively, which was significantly lower than that only after exposure to hypoxia for 6 h (2.67 +/- 1.38, P < 0.05). The nuclear translocation of HIF-1alpha induced by hypoxia was also obviously inhibited by oligomycin pretreatment.

CONCLUSIONOligomycin, a specific inhibitor of respiratory chain, inhibits HIF-1alpha activation, which suggests that mitochondria respiratory chain may play an important role in aforementioned process.

Blotting, Western ; Cell Hypoxia ; Cells, Cultured ; Epithelial Cells ; drug effects ; metabolism ; Humans ; Hypoxia-Inducible Factor 1, alpha Subunit ; metabolism ; Intestines ; cytology ; Oligomycins ; pharmacology

Glucose prevents the development of diabetes induced by alloxan. In the present study, the protective mechanism of glucose against alloxan-induced beta-cell damage was investigated using HIT-T 15 cell, a Syrian hamster transformed beta-cell line. Alloxan caused beta-cell damages with DNA fragmentation, inhibition of glucose-stimulated insulin release, and decrease of cellular ATP level, but all of these beta-cell damages by alloxan were prevented by the presence of 20 mM glucose. Oligomycin, a specific inhibitor of ATP synthase, completely abolished the protective effects of glucose against alloxan-induced cell damage. Furthermore, treatment of nuclei isolated from HIT-T15 cells with ATP significantly prevented the DNA fragmentation induced by Ca2+. The results indicate that ATP produced during glucose metabolism plays a pivotal role in the protection of glucose against alloxan-induced beta-cell damage.
Adenosine Triphosphate/pharmacology ; Adenosine Triphosphate/metabolism ; Alloxan/pharmacology* ; Animal ; B-Lymphocytes/metabolism ; B-Lymphocytes/drug effects* ; B-Lymphocytes/cytology ; Calcium/pharmacology ; Cell Line ; Cell Nucleus/genetics ; Cell Nucleus/drug effects ; Cell Survival ; DNA/metabolism ; DNA/genetics ; DNA/drug effects ; DNA Fragmentation ; Dose-Response Relationship, Drug ; Egtazic Acid/pharmacology ; Glucose/pharmacology* ; Insulin/secretion ; Oligomycins/pharmacology