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Objective To investigate the effects of glycogen synthase kinase-3β (GSK-3β) and β-catenin signaling on the human renal proximal tubular epithelial HK-2 cell injury induced by depleted uranium(DU),and provide a new enlightenment for the development of DU antidotes.Methods H K-2 cells were exposed to different concentrations of DU for 3-24 h,then the protein expressions of kidney injury molecule 1 (KIM-1),neutrophil gelatinase-associated lipocalin (NGAL) and nuclear β-catenin were detected by immunofluorescence staining.The protein expressions of p-GSK-3 β(S9),GSK-3β and cmyc were detected by Western blot assay.HK-2 cells were transiently transfected by GSK-3β (KD) plasmid or treated by TDZD-8 to inhibit the activity of GSK-3β specifically.Other HK-2 cells were transiently transfected by β-catenin plasmid to overexpress the β-catenin protein.Results The percentages of KIM-1 and NGAL-positive cells increased with DU exposure time and concentrations from 300 and 600 μmol/L,and they were significantly higher than those of the blank control at 6-24 h of DU exposure (KIM-1-positive cells:t =11.06,18.97,30.49,P ＜0.05;t =6.79,16.02,85.45,P ＜ 0.05;NGAL-positive cells:t =11.78,11.37,34.29,P ＜0.05;t =7.34,21.63,36.84,P ＜0.05).In contrast,the ratio of p-GSK-3β (S9) to GSK-3β and percentage of nuclear β-catenin-positive cells were significantly higher than that of the blank control at 3-24 h of DU exposure (p-GSK-3β(S9)/GSK-3β:t =3.95,4.69,5.40,3.34,P ＜ 0.05;nuclear β-catenin-positive cells:t =4.61,6.52,36.64,14.93,P ＜ 0.05) with a maximum response at 9 h of DU exposure accompanied with corresponding increase of protein level of c-myc,a downstream target gene of β-catenin.Transient transfection of HK-2 cells with GSK-3β (KD) plasmid significantly inhibited the activity of GSK-3β (t =8.07,P ＜ 0.05) and reduced the DU-increased percentage of KIM-1-positive cells (t =24.77,P ＜ 0.05).Treatment cells with TDZD-8 inhibited the activity of GSK-3β and enhanced the percentage of nuclear β-catenin-positive cells,and it also significantly reduced the percentage of KIM-1-positive cells in HK-2 cells exposed to DU (t =6.25,6.73,P ＜ 0.05).Moreover,overexpression of β-catenin significantly reduced DU-induced cell injury (t =7.48,P ＜ 0.05).Conclusions GSK-3β/β-catenin signaling plays a key role in regulating the DU-induced cytotoxicity of HK-2 cells.Inhibition of GSK-3β activity and overexpression of β-catenin can protect the HK-2 cells from DU-induced damage.
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Objective To investigate the radiosensitization effect of antihelminthic niclosamide on human triple-negative breast cancer MDA-MB-231 cells and the potential mechanism related to Wnt/β-catenin signaling pathway.Methods Four methyl thiazolyl tetrazolium(MTT) assay was used to measure the effect of niclosamide on cell viability at different concentrations and 50％ inhibitory concentration(IC50)value was calculated.MDA-MB-231 cells were divided into 4 groups:untreated control,niclosamide treatment alone group,radiation alone group and niclosamide plus radiation treatment group.The cells with or without 1.0 and 1.5 μmol/L niclosamide pre-treatment were irradiated with 137Cs γ-rays at doses of 0,2,4 and 6 Gy.Cell survival was assayed with the colony formation method,radiation-induced γH2AX foci was analyzed with immunofluorescence,cell cycle progression was assayed with flow cytometry,and the changes of phospho-and non-phospho-β-catenin and Cyclin D1 protein expressions were measured with Western blot.Results Niclosamde obviously inhibited the viability of MDA-MB-231 cells in a dosedependent manner with a IC50 value of 13.63 μmol/L.Pretreatment of cells with 1.0 and 1.5 μmol/L niclosamide evidently enhanced the radiosensitivity of MDA-MB-231 cells to γ-rays,and the values of SER were 1.37 and 1.62,respectively.Niclosamide pretreatment significantly increased radiation-induced γH2AX foci formation(t =3.91,P ＜0.05),diminished the radiation-induced G2/M arrest(t =8.05,P ＜0.01),and inhibited radiation-induced expressions of phospho-β-catenin (S675),non-phospho-β-catenin and Cyclin D1 proteins in MDA-MB-231 cells.Conclusions Niclosamide significantly can enhance the sensitivity of MDA-MB-231 cells to γ-ray irradiation through inhibiting Wnt/β-catenin signaling pathway,which results in the inhibition of DNA DSBs repair and the reduction of radiation-induced G2/M arrest.Wnt/β-catenin signaling pathway may serve as an ideal molecular target for radiosensitization of triplenegative breast cancer.
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Objective To investigate the characteristics of repair of DNA double strand breaks (DSB) induced by high-LET α-particle irradiation and their relationship with chromatin structure in the G0 lymphocytes of human peripheral blood,in order to provide the experimental basis for the judgement and dose evaluation of internal α-particle radiation.Methods Peripheral whole blood were collected from four healthy adults and lymphocytes were separated.A monocellular layer of human lymphocytes attached in Mylar film were irradiated with 0 and 0.5 Gy of α-particles and the lymphocytes suspensions were irradiated with 0 and 0.5 Gy of γ-rays.The formations of γH2AX foci as a surrogate marker of DSB and Rad51 foci as a marker of homologous recombination (HR) repair and their spatial localization in chromatin structure were measured by immunofluorescence staining technique at 10 min-48 h post-irradiation.Results Linear-γH2AX foci tracks were observe at 10 min-2 h post-irradiation in lymphocytes exposed to α-particle irradiation(t =11.12,14.40,16.56,P ＜ 0.05),and almost completely disppeared at 6 h postirradiation.The frequencies of γH2AX foci peaked at 30 min after α-particle irradiation (t =51.72,P ＜0.05) and then decreased rapidly during 6 h post-irradiation (t =29.83,P ＜ 0.05).The average number of foci remained only about 16％ at 24-48 h post-irradiation.Moreover,27％ of γH2AX foci located at DAPI-bright heterochromatin region at 10 min after α-particle radiation,suggesting that the efficacy of DSB repair may be decreased.In contrast,at 10 min-48 h after γ-ray irradiation,no linear γH2AX foci track was observed and the γH2AX foci diffused randomly in nucleus and predominantly located in DAPI-weak euchromatin region.The numbers of formative and residual γH2AX foci after γ-ray irradiation were significantly less than those after α-particle radiation.During 30 min-2 h after α-particle and γ-ray irradiation,the frequencies of Rad51 foci slightly but not significantly increased in comparison with background level,and the frequencies of co-localization of Rad51 foci and γH2AX foci were only 3％-8％.Conclusions The formation of linear γH2AX foci tracks induced by high-LET α-particle irradiation in Go human lymphocyte could be used as biological indicator to estimate whether a person has been exposed to internal α-particle radiation.Prolonged persistence of residual γH2AX foci may be applicable for biological dosimetry.
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Objective To explore the dose- and time-responses of BPCBG on the decorporation of uranium and its protective effects for uranium-induced kidney injury in rats. Methods Sprague-Dawley (SD) male rats were randomly divided into 4 -7 groups:normal control group,uranium poisoning group,different doses of BPCBG groups and DTPA-CaNa3 group. Rats in chelating agents-treated groups were either injected intramuscularly with 60,120 and 600 μmol/kg of BPCBG or 120 and 600 μmol/kg of DTPA-CaNa3 immediately after intraperitoneal injection of uranyl acetate dihydrate,or injected with 120 μmol/kg of BPCBG 0.5,2 h before or 0,0.5,1 and 2 h after injection of uranium. Uranium poisoning group rats were injected with normal saline after intraperitoneal injection of uranyl acetate dihydrate,and the normal control group rats were merely injected with normal saline. The uranium content in urine,kidney and femurs were detected 24 h after chelator injections by ICP-MS method.After injecting a dose of 500 μg uranyl acetate dihydrate,rats were injected with 600 μmol/kg of BPCBG or 1200 μmol/kg of DTPA-CaNa3. Histopathological changes in the kidney and serum creatinine and urea nitrogen were examined 48 h after chelator administration.Results Prompt injections of BPCBG resulted in 37％ -61％ ( t =2.22,4.43,5.80,P ＜ 0.05 ) increase in 24 h-urinary uranium excretion,and significantly decreased the levels of uranium in kidney and bone by 59％ -69％ (t=3.33,5-59,4-53,P＜0.01) and 14％ -58％ (t =2.15,8.70,9.10,P ＜ 0.05 ) respectively in a dose-dependent manner. BPCRG injection obviously reduced the severity of the uranium-induced histological alterations in the kidney,which was in parallel with the amelioration noted in serum indicators,serum creatinine and urea nitrogen,of uranium nephrotoxicity.Advanced 0.5 h or delayed 0.5 and 1 h administrations of BPCBG were effective in 24 h-urinary uranium excretion ( advanced 0.5 h:t =4.34,delayed 0.5 h:t =3.35,P ＜ 0.05 ),decreasing accumulation of kidney uranium ( t =5.75,7.74,5.87,P ＜ 0.05 ) and accumulation of hone uranium (t =6.43,5.222,2.60,P ＜0.05),but the efficacy decreased with the interval time between uranium and BPCBG injection. Although DTPA-CaNa3 markedly reduced uranium retention in kidney (120,600 μmol/kg,t =2.28,3.35,P ＜ 0.05 ),its efficacy in uranium removal was significantly lower than that of BPCBG,and it had no protective effects against uranium-induced nephrotoxicity.Conclusions BPCBG can effectively decorporate uranium from rats and protect against uranium-induced kidney injury of rats.
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This study is to assess the efficacy of BPCBG on the decorporation of uranium (VI) and protecting human renal proximal tubular epithelial cells (HK-2) against uranium-induced damage. BPCBG at different doses was injected intramuscularly to male SD rats immediately after a single intraperitoneal injection of UO2(CH3COO)2. Twenty-four hours later uranium contents in urine, kidneys and femurs were measured by ICP-MS. After HK-2 cells were exposed to UO2(CH3COO)2 immediately or for 24 h followed by BPCBG treatment at different doses for another 24 or 48 h, the uranium contents in HK-2 cells were measured by ICP-MS, the cell survival was assayed by cell counting kit-8 assay, formation of micronuclei was determined by the cytokinesis-block (CB) micronucleus assay and the production of intracellular reactive oxygen species (ROS) was detected by 2',7'-dichlorofluorescin diacetate (DCFH-DA) oxidation. DTPA-CaNa3 was used as control. It was found that BPCBG at dosages of 60, 120, and 600 micromol kg(-1) resulted in 37%-61% increase in 24 h-urinary uranium excretion, and significantly decreased the amount of uranium retention in kidney and bone to 41%-31% and 86%-42% of uranium-treated group, respectively. After HK-2 cells that had been pre-treated with UO2(CH3COO)2 for 24 h were treated with the chelators for another 24 h, 55%-60% of the intracellular uranium was removed by 10-250 micromol L(-1) of BPCBG. Treatment of uranium-treated HK-2 cells with BPCBG significantly enhanced the cell survival, decreased the formation of micronuclei and inhibited the production of intracellular ROS. Although DTPA-CaNa3 markedly reduced the uranium retention in kidney of rats and HK-2 cells, its efficacy of uranium removal from body was significantly lower than that of BPCBG and it could not protect uranium-induced cell damage. It can be concluded that BPCBG effectively decorporated the uranium from UO2(CH3COO)2-treated rats and HK-2 cells, which was better than DTPA-CaNa3. It could also scavenge the uranium-induced intracellular ROS and protect against the uranium-induced cell damage. BPCBG is worth further investigation.