AIM:To study the mechanism of 5-fluorouracil(5-FU)resistance in colon cancer cells and to develop strategies for overcoming such resistance by combination treatment.METHODS:We established and characterized a 5-FU resi...AIM:To study the mechanism of 5-fluorouracil(5-FU)resistance in colon cancer cells and to develop strategies for overcoming such resistance by combination treatment.METHODS:We established and characterized a 5-FU resistance(5-FU-R)cell line derived from continuous exposure(25μmol/L)to 5-FU for 20 wk in 5-FU sensitive HCT-116 cells.The proliferation and expression of different representative apoptosis and anti-apoptosis markers in 5-FU sensitive and 5-FU resistance cells were measured by the MTT assay and by Western blotting,respectively,after treatment with Resveratrol(Res)and/or 1,3-Bis(2-chloroethyl)-1-nitrosourea(BCNU).Apoptosis and cell cycle arrest was measured by 4',6'-diamidino-2-phenylindole hydrochloride staining and fluorescence-activated cell sorting analysis,respectively.The extent of DNA damage was measured by the Comet assay.We measured the visible changes in the DNA damage/repair cascade by Western blotting.RESULTS:The widely used chemotherapeutic agents BCNU and Res decreased the growth of 5-FU sensitive HCT-116 cells in a dose dependent manner.Combined application of BCNU and Res caused more apoptosis in5-FU sensitive cells in comparison to individual treatment.In addition,the combined application of BCNU and Res caused a significant decrease of major DNA base excision repair components in 5-FU sensitive cells.We established a 5-FU resistance cell line(5-FU-R)from 5-FU-sensitive HCT-116(mismatch repair deficient)cells that was not resistant to other chemotherapeutic agents(e.g.,BCNU,Res)except 5-FU.The 5-FU resistance of 5-FU-R cells was assessed by exposure to increasing concentrations of 5-FU followed by the MTT assay.There was no significant cell death noted in5-FU-R cells in comparison to 5-FU sensitive cells after5-FU treatment.This resistant cell line overexpressed anti-apoptotic[e.g.,AKT,nuclear factorκB,FLICE-like inhibitory protein),DNA repair(e.g.,DNA polymerase beta(POL-β),DNA polymerase eta(POLH),protein Flap endonuclease 1(FEN1),DNA damage-binding protein 2(DDB2)]and 5-FU-resistance proteins(thymidylate synthase)but under expressed pro-apoptotic proteins(e.g.,DAB2,CK1)in comparison to the parental cells.Increased genotoxicity and apoptosis were observed in resistant cells after combined application of BCNU and Res in comparison to untreated or parental cells.BCNU increased the sensitivity to Res of 5-FU resistant cells compared with parental cells.Fifty percent cell death were noted in parental cells when 18μmol/L of Res was associated with fixed concentration(20μmol/L)of BCNU,but a much lower concentration of Res(8μmol/L)was needed to achieve the same effect in 5-FU resistant cells.Interestingly,increased levels of adenomatous polyposis coli and decreased levels POL-β,POLH,FEN1 and DDB2 were noted after the same combined treatment in resistant cells.CONCLUSION:BCNU combined with Res exerts a synergistic effect that may prove useful for the treatment of colon cancer and to overcome drug resistance.展开更多
Decontamination of 2-chloroethyl ethyl sulfide (2-CEES, CH_3CH_2SCH_2CH_2C1) by pulsed corona plasma was investigated. The results show that 212.6 mg/m^3 of 2-CEES, with the gas flow rate of 2 m^3/h, can be decontam...Decontamination of 2-chloroethyl ethyl sulfide (2-CEES, CH_3CH_2SCH_2CH_2C1) by pulsed corona plasma was investigated. The results show that 212.6 mg/m^3 of 2-CEES, with the gas flow rate of 2 m^3/h, can be decontaminated to 0.09 mg/m^3. According to the variation of the inlet and outlet concentration of 2-CEES vapor with retention time, it is found that the reaction of 2-CEES in a pulsed corona plasma system follows the first order reaction, with the reaction rate constant of 0.463 s^-1. The decontamination mechanism is discussed based on an analysis of the dissociation energy of chemical bonds and decontamination products. The C-S bond adjacent to the C1 atom will be destroyed firstly to form CH3CH2S. and .CH2CH2C1 radicals. CH3CH2S. can be decomposed to .C_2H_5 and .S..S can be oxidized to SO_2, while .C_2H_5 can be finally oxidized to CO_2 and H_2O. The C-Cl bond in the .CH_2CH_2C1 radical can be destroyed to form .CH_2CH_2. and .C1, which can be mineralized to CO_2, H_2O and HCl. The H atom in the .CH_2CH_2C1 radical can also be substituted by -C1 to form CHCl_2-CHCl_2.展开更多
BACKGROUND: The implantation of released chemotherapeutic drugs, which takes biodegradable polymer as vector, into the tumor site can get high concentration and release the drug for a long time, it can directly act on...BACKGROUND: The implantation of released chemotherapeutic drugs, which takes biodegradable polymer as vector, into the tumor site can get high concentration and release the drug for a long time, it can directly act on the tumor cells, and reduce the general toxicity. OBJECTIVE: To explore the in vitro and in vivo course of 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) sustained-release from BCNU-loaded polylactide (PLA) microspheres (MS) and location in rat brain tissue. DESIGN: A repetitive measurement. SETTING:Central Pharmacy, General Hospital of Chinese People’s Armed Police Forces. MATERIALS: Thirty male SD rats were used. PLA (Mr5000, batch number: KSL8377) was produced by Wako Pure Chemical Inc.,Ltd. (Japan); BCNU (batch number: 021121) by Tianjin Jinyao Amino Acid Co., Ltd.; BCNU-PLA-MS was prepared by the method of solvent evaporation and pressed into tablets (10 mg/tablet). High-performance liquid chromatography (HPLC) Agilent 1100 (USA); LS9800 liquid-scintillation radiometric apparatus (Beckman). Chromatographic conditions: Elite Hypersil ODS2 C18 chromatographic column (5 μm, 4.6 mm×150 mm); Mobile phase: methanol: water (50:50), flow rate was 1.0 mL per minute, wave length of ultraviolet detection was 237 nm, and the inlet amount of samples was 10 μL. METHODS: The experiments were carried out in the experimental animal center of the General Hospital of Chinese Armed Police from May 2004 to July 2005. ① In vitro BCNU-PLA-MS release test: BCNU-PLA-MS was prepared by the method of solvent evaporation, then placed in 0.1 mol/L phosphate buffered solution (PBS, pH 7.4, 37 ℃), part of MS were taken out at 1, 2, 3, 7, 10 and 15 days respectively, and the rest amount of BCNU in MS was determined by HPLC, then the curve of BCNU-PLA-MS release was drawn. ②In vivo BCNU-PLA-MS release and distribution test: The rats were anesthetized, then BCNU-PLA-MS were implanted to the site 1 mm inferior to the cortex of frontal lobe. Five rats were killed postoperatively at 4 hours, 1, 2, 3, 7 and 15 days, the residual MS was removed from the brain tissue. The rest amount of BCNU was determined with HLPC, and the curve of BCNU-PLA-MS release was drawn as compared with the amount of BCNU in the implanted tablets. Besides, brain tissues (1 g) at the implanted side and the contralateral one were obtained respectively, blood sample (0.5 mL) was also collected, 3H-BCNU was counted radioactively in radioactive liquid flash solution. The distributions of BCNU-PLA-MS in normal rat brain tissue and serum were detected. The analysis of variance was applied to compare the intergroup differences of the measurement data. MAIN OUTCOME MEASURES: ① Characteristics of BCNU-PLA-MS release in phosphate buffered solution (PBS) and rat brain tissue; ② Distributions of BCNU-PLA-MS in normal rat brain tissue and serum. RESULTS: ① Release of BCNU-PLA-MS in PBS and rat brain tissue: The BCNU released from BCNU-PLA-MS could be sustained for over 2 weeks both in PBS and brain tissue. In PBS, the released rate of BCNU was over 15% at 24 hours, nearly 50% at 72 hours and over 90% at 15 days. In brain tissue, the released rate was 8% at 4 hours, 16% at 24 hours, 60% at 72 hours, respectively, and BCNU could be sustained released for over 15 days. ② Distributions of BCNU-PLA-MS in normal rat brain tissue and serum: The concentrations of BCNU in the ipsilateral brain tissue were 6 to 70 times higher than those in the contralateral one. The concentrations of BCNU in the ipsilateral brain tissue were obviously higher than those in serum and contralateral brain tissue (F =103.47, P < 0.01). CONCLUSION: BCNU-PLA-MS can increase the drug concentration in targeted brain tissue, decrease that in the non-targeted brain tissue, reduce general toxic and side effects, and have good releasing function.展开更多
Tris(2-chloroethyl) phosphate(TCEP) is a typical phosphate flame retardant. Its potential adverse health effects have recently aroused concern. We investigated the seasonal variations of TCEP concentrations in the raw...Tris(2-chloroethyl) phosphate(TCEP) is a typical phosphate flame retardant. Its potential adverse health effects have recently aroused concern. We investigated the seasonal variations of TCEP concentrations in the raw, finished and tap water samples from two drinking water treatment plants(DWTPs) in China, and evaluated the cytotoxicity and apoptosis/necrosis of organic extracts(OEs) in water samples. We enriched TCEP and OEs in water samples by solid-phase extraction method. The TCEP concentrations in water samples were determined by gas chromatography–mass spectrometry. Normal human liver cell line L02 was treated with OEs in the water samples, and then the cytotoxicity and apoptosis/necrosis were measured by 3-(4, 5-dimethyithiazol-2-yl)-2,5-diphenyl-tetrazolium bromide assay and flow cytometry, respectively. The results showed that cytotoxicities of OEs in raw water samples from both DWTPs in summer and winter were stronger than those in spring and autumn, cytotoxicity of OEs in finished and tap water samples from both DWTPs in summer and autumn were stronger than those in spring and winter. In all seasons, the maximal concentrations(100 mL water/mL cell culture) of OEs in the raw water samples from both DWTPs induced late apoptosis/necrosis. The reasons for seasonal variations of TCEP in water samples and potential toxic effects of other pollutants in the water samples need to be further investigated.展开更多
Three CeO_2 samples with different morphologies, i.e., cubes, rods, and spindles, were synthesized and investigated for 2-chloroethyl ethyl sulfide(2-CEES) degradation. The samples were characterized using scanning ...Three CeO_2 samples with different morphologies, i.e., cubes, rods, and spindles, were synthesized and investigated for 2-chloroethyl ethyl sulfide(2-CEES) degradation. The samples were characterized using scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, the Brunauer-Emmett-Teller method, and temperature-programmed CO_2 desorption. It was found that morphologies of CeO_2 could strongly affect the surface properties and the 2-CEES degradation activities. The surface basicity and the continuous 2-CEES degradation activity of spindle-like CeO_2 were much better than those of the other CeO_2 samples, although all the samples had identical chemical compositions. That was benefited by the largest surface area, abundant microcracks, and surface oxygen vacancies of the spindle-like CeO_2.展开更多
基金Supported by Indian Council of Medical Research and Department of Biotechnology,Government of India
文摘AIM:To study the mechanism of 5-fluorouracil(5-FU)resistance in colon cancer cells and to develop strategies for overcoming such resistance by combination treatment.METHODS:We established and characterized a 5-FU resistance(5-FU-R)cell line derived from continuous exposure(25μmol/L)to 5-FU for 20 wk in 5-FU sensitive HCT-116 cells.The proliferation and expression of different representative apoptosis and anti-apoptosis markers in 5-FU sensitive and 5-FU resistance cells were measured by the MTT assay and by Western blotting,respectively,after treatment with Resveratrol(Res)and/or 1,3-Bis(2-chloroethyl)-1-nitrosourea(BCNU).Apoptosis and cell cycle arrest was measured by 4',6'-diamidino-2-phenylindole hydrochloride staining and fluorescence-activated cell sorting analysis,respectively.The extent of DNA damage was measured by the Comet assay.We measured the visible changes in the DNA damage/repair cascade by Western blotting.RESULTS:The widely used chemotherapeutic agents BCNU and Res decreased the growth of 5-FU sensitive HCT-116 cells in a dose dependent manner.Combined application of BCNU and Res caused more apoptosis in5-FU sensitive cells in comparison to individual treatment.In addition,the combined application of BCNU and Res caused a significant decrease of major DNA base excision repair components in 5-FU sensitive cells.We established a 5-FU resistance cell line(5-FU-R)from 5-FU-sensitive HCT-116(mismatch repair deficient)cells that was not resistant to other chemotherapeutic agents(e.g.,BCNU,Res)except 5-FU.The 5-FU resistance of 5-FU-R cells was assessed by exposure to increasing concentrations of 5-FU followed by the MTT assay.There was no significant cell death noted in5-FU-R cells in comparison to 5-FU sensitive cells after5-FU treatment.This resistant cell line overexpressed anti-apoptotic[e.g.,AKT,nuclear factorκB,FLICE-like inhibitory protein),DNA repair(e.g.,DNA polymerase beta(POL-β),DNA polymerase eta(POLH),protein Flap endonuclease 1(FEN1),DNA damage-binding protein 2(DDB2)]and 5-FU-resistance proteins(thymidylate synthase)but under expressed pro-apoptotic proteins(e.g.,DAB2,CK1)in comparison to the parental cells.Increased genotoxicity and apoptosis were observed in resistant cells after combined application of BCNU and Res in comparison to untreated or parental cells.BCNU increased the sensitivity to Res of 5-FU resistant cells compared with parental cells.Fifty percent cell death were noted in parental cells when 18μmol/L of Res was associated with fixed concentration(20μmol/L)of BCNU,but a much lower concentration of Res(8μmol/L)was needed to achieve the same effect in 5-FU resistant cells.Interestingly,increased levels of adenomatous polyposis coli and decreased levels POL-β,POLH,FEN1 and DDB2 were noted after the same combined treatment in resistant cells.CONCLUSION:BCNU combined with Res exerts a synergistic effect that may prove useful for the treatment of colon cancer and to overcome drug resistance.
基金supported by State Key Laboratory of NBC Protection for Civilian,China
文摘Decontamination of 2-chloroethyl ethyl sulfide (2-CEES, CH_3CH_2SCH_2CH_2C1) by pulsed corona plasma was investigated. The results show that 212.6 mg/m^3 of 2-CEES, with the gas flow rate of 2 m^3/h, can be decontaminated to 0.09 mg/m^3. According to the variation of the inlet and outlet concentration of 2-CEES vapor with retention time, it is found that the reaction of 2-CEES in a pulsed corona plasma system follows the first order reaction, with the reaction rate constant of 0.463 s^-1. The decontamination mechanism is discussed based on an analysis of the dissociation energy of chemical bonds and decontamination products. The C-S bond adjacent to the C1 atom will be destroyed firstly to form CH3CH2S. and .CH2CH2C1 radicals. CH3CH2S. can be decomposed to .C_2H_5 and .S..S can be oxidized to SO_2, while .C_2H_5 can be finally oxidized to CO_2 and H_2O. The C-Cl bond in the .CH_2CH_2C1 radical can be destroyed to form .CH_2CH_2. and .C1, which can be mineralized to CO_2, H_2O and HCl. The H atom in the .CH_2CH_2C1 radical can also be substituted by -C1 to form CHCl_2-CHCl_2.
文摘BACKGROUND: The implantation of released chemotherapeutic drugs, which takes biodegradable polymer as vector, into the tumor site can get high concentration and release the drug for a long time, it can directly act on the tumor cells, and reduce the general toxicity. OBJECTIVE: To explore the in vitro and in vivo course of 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) sustained-release from BCNU-loaded polylactide (PLA) microspheres (MS) and location in rat brain tissue. DESIGN: A repetitive measurement. SETTING:Central Pharmacy, General Hospital of Chinese People’s Armed Police Forces. MATERIALS: Thirty male SD rats were used. PLA (Mr5000, batch number: KSL8377) was produced by Wako Pure Chemical Inc.,Ltd. (Japan); BCNU (batch number: 021121) by Tianjin Jinyao Amino Acid Co., Ltd.; BCNU-PLA-MS was prepared by the method of solvent evaporation and pressed into tablets (10 mg/tablet). High-performance liquid chromatography (HPLC) Agilent 1100 (USA); LS9800 liquid-scintillation radiometric apparatus (Beckman). Chromatographic conditions: Elite Hypersil ODS2 C18 chromatographic column (5 μm, 4.6 mm×150 mm); Mobile phase: methanol: water (50:50), flow rate was 1.0 mL per minute, wave length of ultraviolet detection was 237 nm, and the inlet amount of samples was 10 μL. METHODS: The experiments were carried out in the experimental animal center of the General Hospital of Chinese Armed Police from May 2004 to July 2005. ① In vitro BCNU-PLA-MS release test: BCNU-PLA-MS was prepared by the method of solvent evaporation, then placed in 0.1 mol/L phosphate buffered solution (PBS, pH 7.4, 37 ℃), part of MS were taken out at 1, 2, 3, 7, 10 and 15 days respectively, and the rest amount of BCNU in MS was determined by HPLC, then the curve of BCNU-PLA-MS release was drawn. ②In vivo BCNU-PLA-MS release and distribution test: The rats were anesthetized, then BCNU-PLA-MS were implanted to the site 1 mm inferior to the cortex of frontal lobe. Five rats were killed postoperatively at 4 hours, 1, 2, 3, 7 and 15 days, the residual MS was removed from the brain tissue. The rest amount of BCNU was determined with HLPC, and the curve of BCNU-PLA-MS release was drawn as compared with the amount of BCNU in the implanted tablets. Besides, brain tissues (1 g) at the implanted side and the contralateral one were obtained respectively, blood sample (0.5 mL) was also collected, 3H-BCNU was counted radioactively in radioactive liquid flash solution. The distributions of BCNU-PLA-MS in normal rat brain tissue and serum were detected. The analysis of variance was applied to compare the intergroup differences of the measurement data. MAIN OUTCOME MEASURES: ① Characteristics of BCNU-PLA-MS release in phosphate buffered solution (PBS) and rat brain tissue; ② Distributions of BCNU-PLA-MS in normal rat brain tissue and serum. RESULTS: ① Release of BCNU-PLA-MS in PBS and rat brain tissue: The BCNU released from BCNU-PLA-MS could be sustained for over 2 weeks both in PBS and brain tissue. In PBS, the released rate of BCNU was over 15% at 24 hours, nearly 50% at 72 hours and over 90% at 15 days. In brain tissue, the released rate was 8% at 4 hours, 16% at 24 hours, 60% at 72 hours, respectively, and BCNU could be sustained released for over 15 days. ② Distributions of BCNU-PLA-MS in normal rat brain tissue and serum: The concentrations of BCNU in the ipsilateral brain tissue were 6 to 70 times higher than those in the contralateral one. The concentrations of BCNU in the ipsilateral brain tissue were obviously higher than those in serum and contralateral brain tissue (F =103.47, P < 0.01). CONCLUSION: BCNU-PLA-MS can increase the drug concentration in targeted brain tissue, decrease that in the non-targeted brain tissue, reduce general toxic and side effects, and have good releasing function.
基金supported by the National Natural Science Foundations of China (Nos.81273023 and 81472947)
文摘Tris(2-chloroethyl) phosphate(TCEP) is a typical phosphate flame retardant. Its potential adverse health effects have recently aroused concern. We investigated the seasonal variations of TCEP concentrations in the raw, finished and tap water samples from two drinking water treatment plants(DWTPs) in China, and evaluated the cytotoxicity and apoptosis/necrosis of organic extracts(OEs) in water samples. We enriched TCEP and OEs in water samples by solid-phase extraction method. The TCEP concentrations in water samples were determined by gas chromatography–mass spectrometry. Normal human liver cell line L02 was treated with OEs in the water samples, and then the cytotoxicity and apoptosis/necrosis were measured by 3-(4, 5-dimethyithiazol-2-yl)-2,5-diphenyl-tetrazolium bromide assay and flow cytometry, respectively. The results showed that cytotoxicities of OEs in raw water samples from both DWTPs in summer and winter were stronger than those in spring and autumn, cytotoxicity of OEs in finished and tap water samples from both DWTPs in summer and autumn were stronger than those in spring and winter. In all seasons, the maximal concentrations(100 mL water/mL cell culture) of OEs in the raw water samples from both DWTPs induced late apoptosis/necrosis. The reasons for seasonal variations of TCEP in water samples and potential toxic effects of other pollutants in the water samples need to be further investigated.
基金supported by the National Key Research and Development Program of China(2016YFC0205001)
文摘Three CeO_2 samples with different morphologies, i.e., cubes, rods, and spindles, were synthesized and investigated for 2-chloroethyl ethyl sulfide(2-CEES) degradation. The samples were characterized using scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, the Brunauer-Emmett-Teller method, and temperature-programmed CO_2 desorption. It was found that morphologies of CeO_2 could strongly affect the surface properties and the 2-CEES degradation activities. The surface basicity and the continuous 2-CEES degradation activity of spindle-like CeO_2 were much better than those of the other CeO_2 samples, although all the samples had identical chemical compositions. That was benefited by the largest surface area, abundant microcracks, and surface oxygen vacancies of the spindle-like CeO_2.