PCB153对原代培养大鼠睾丸支持细胞SOD活性、DNA损伤及凋亡的影响

目的：探讨2,2′,4,4′,5-五氯联苯（2,2′,4,4′,5-hexachlorobiphenyl,PCB153）暴露对原代培养大鼠睾丸支持细胞（Sertoli cells,SC）超氧化物歧化酶（superoxide dismutase,SOD）活性、DNA损伤、细胞凋亡的影响以及抗氧化剂N-乙酰半胱氨酸（N-acetyl-L-cysteine,NAC）的干预作用。方法：原代培养出生18～20d雄性SD大鼠的睾丸支持细胞,设PCB153不同浓度的染毒组（加入10、20、30μmol/L PCB153）,NAC组（以300μmol/L NAC预处理1h后加入30μmol/L PCB153）,和对照组（加入与PCB153最大染毒量等体积的DMSO）,各组细胞经上述处理后继续培养24h,用SOD试剂盒测定各组细胞SOD活性,彗星实验测定DNA损伤程度,流式细胞术检测细胞凋亡,细胞荧光标记观察凋亡形态。结果：染毒24h后,大鼠睾丸支持细胞SOD活性随着PCB153染毒剂量的升高而降低,20、30μmol/L染毒组显著低于对照组（P〈0.05）,NAC预处理可提升SOD活性（P〈0.05）。各PCB153处理组及NAC预处理组与对照组相比,DNA损伤间的差异均无统计学意义（P〉0.05）,细胞凋亡率则均显著增加（P〈0.05）,NAC预处理可降低PCB153所致的凋亡率（P〈0.05）。结论：10～30μmol/L PCB153染毒24h可诱导的原代培养大鼠SCSOD活性降低,细胞凋亡增加,但并未引起DNA损伤,NAC预处理具有保护作用。     

钬元素对小鼠肝脏细胞DNA损伤的影响

背景与目的: 通过研究钬离子溶液对小鼠肝脏细胞DNA的损伤,探讨钬元素对诱导动物细胞凋亡的影响 。材料与方法: 处理组1： 小鼠定时灌胃氯化钬溶液50 mg/(kg•d),连续5 d; 组 2～3： 小鼠分别定时腹腔注射氯化钬溶液60 mg/(kg•d)和120 mg/(kg•d),连续2 d; 组4： 小鼠一次性腹腔注射氯化钬溶液320 mg/kg; 每次染毒相间24 h,组1～4： 小鼠均在末次染毒24 h后处死,提取肝脏DNA。 组5： 小鼠一次性腹腔注射等体积生理盐水; 组6～9： 小鼠一次性腹腔注射氯化钬溶液80 mg/kg,分别于注射后12、24、48和96 h处死小鼠提取肝脏DNA。通过琼脂糖凝胶电泳研究各组DNA带型变化。 结果：处理组7 DNA电泳中出现连续的弥散带型,其它各组均未观察到明显的拖尾现象。也未观察到“DNA ladder"。 结论： 钬离子对小鼠肝脏细胞DNA的断裂作用可能与其剂量大小、处理时间及DNA修复作用有关,而且无特异性。本实验结果表明,钬元素未诱导小鼠肝脏细胞凋亡。     

甲醛对HepG2细胞脂肪代谢的影响

目的： 探讨甲醛对HepG2细胞甘油三酯 (triglyceride,TG)含量的影响及其可能机制。方法：以0.02、0.1、0.5、2.5、12.5 mmol/L的甲醛 (formaldehyde,FA)分别处理人肝癌HepG2细胞24和48 h,采用CCK-8法检测细胞活性,GPO-POD 酶法测定细胞内TG含量。另分别以0.004、0.02、0.1 mmol/L的甲醛处理人肝癌HepG2细胞24和48 h,采用Western blot法检测肉碱棕榈酰转移酶1 (carnitine palmitoyl transferase 1,CPT1)、固醇调节元件结合蛋白-1c (sterol regulatory element-binding protern-1c,SREBP-1c)、腺苷酸核糖基化因子1 (ADP-ribosylation factor 1,Arf1)和包被蛋白Ⅰ (coat protein comlex Ⅰ,COPⅠ)的蛋白表达水平。结果：与对照组比较,0.5～12.5 mmol/L FA染毒24 h或0.1～12.5 mmol/L染毒48 h 时可显著降低HepG2细胞活性 (P均<0.05);0.1 mmol/L FA染毒24 h,或者0.1 和0.02 mmol/L FA染毒48 h,均可致HepG2细胞内TG含量显著升高 (P均<0.05);FA染毒48 h引起肝细胞内CPT1表达水平明显降低 (P均<0.05),SREBP-1c和COPⅠ表达水平在染毒24和48 h后均增高 (P均<0.05),FA染毒24 h后 Arf1表达水平明显增加 (P<0.05)。结论：FA接触可引起HepG2细胞内TG含量增加,其机制可能与脂肪酸β氧化受到抑制和脂肪合成增加有关。     

甲醛对人肝癌细胞株HepG2内质网应激相关Bip和CANX mRNA及蛋白表达水平的影响

目的：研究甲醛（FA）染毒是否会诱导人肝癌细胞株HepG2内质网应激相关基因Bip和CANX mRNA和蛋白表达水平的改变,引起内质网应激反应。方法：用Hoechst 33258进行核染色,以观察不同浓度（0、0.02、0.1、0.5、2.5、12.5 mmol/L）FA分别染毒肝细胞株24和48 h 后的细胞核形态学变化。再分别用0.004、0.02、0.1 mmol/L的FA处理人肝癌细胞株HepG2细胞24 h和48 h后,采用荧光定量PCR（qPCR）和Western blot检测内质网应激相关基因免疫球蛋白重链结合蛋白（Bip）及钙连蛋白（CANX） mRNA和蛋白的表达水平。结果：Hoechst 33258染色结果表明,染毒24和48 h后,0.5、2.5、12.5 mmol/L FA 组出现大量核呈固缩状态或颗粒状荧光死亡细胞,阴性对照组和0.1 mmol/L及以下剂量组细胞核荧光染色较浅,细胞核未固缩,故后续试验采用0.1 mmol/L及以下剂量。经0.004、0.02和0.1 mmol/L FA处理细胞24和48 h后,qPCR检测结果显示,甲醛各剂量染毒组Bip和CANX的mRNA表达量与阴性对照组比较,差异均无统计学意义（P>0.05）。Western blot结果表明,染毒24 h,不同剂量甲醛处理组与阴性对照组相比,Bip和CANX蛋白表达量均无显著差异（P>0.05）;染毒48 h,与阴性对照组相比,各FA处理组Bip蛋白表达量升高,0.02和0.1 mmol/L FA处理组CANX蛋白表达明显升高,差异均有统计学意义（P < 0.05）。结论：甲醛染毒可诱导HepG2细胞内质网应激相关蛋白Bip和CANX表达水平升高,引起肝细胞发生内质网应激反应。     

p53和γ-H2AX作为乙醛引起DNA损伤早期生物标记物的实验研究

目的： 评价乙醛染毒p53野生型人类淋巴母细胞(TK6)后,细胞中DNA损伤标记物p53、γ-H2AX的表达变化,并与彗星试验中的DNA链断裂指标进行敏感性比较,探讨p53和γ-H2AX 作为乙醛引起DNA损伤的早期生物标记物的可能。方法：乙醛在0.5~20 mmol/L的浓度范围分别染毒TK6细胞20 min、2和12 h后,采用高通量的流式细胞术检测肿瘤抑制蛋白total-p53、磷酸化p53(p-p53)以及磷酸化组蛋白(γ-H2AX)的细胞表达率和表达强度(平均荧光强度);同时采用碱性彗星试验检测乙醛引起的DNA链断裂指标(细胞拖尾率、尾长、尾部DNA百分含量以及尾矩)的变化。结果：乙醛染毒TK6细胞12 h后,γ-H2AX的表达强度在15及20 mmol/L浓度下显著升高(P<0.05),p-p53的细胞表达率在0.5~7.5 mmol/L浓度范围内呈现剂量依赖的升高趋势,total-p53的细胞表达率趋势与p-p53相似,但与阴性对照组相比,差异无统计学意义。彗星试验中,细胞拖尾率、尾长、尾部DNA百分含量以及尾矩在5.0~12.5 mmol/L浓度范围内均增加,并呈现剂量依赖性。染毒2 h后,与阴性对照组相比,total-p53和p-p53的细胞表达率在15和20 mmol/L浓度下显著升高(P均<0.05),细胞拖尾率、尾部DNA百分含量以及尾矩在20 mmol/L浓度升高(P均<0.05)。染毒20 min后,3种生物标志物均未见清晰的变化趋势,4种DNA链断裂指标均未见显著变化(P均＞0.05)。结论：乙醛染毒TK6细胞12 h可诱导p-p53细胞表达率升高、γ-H2AX细胞表达强度升高、 total-p53细胞表达率轻微升高,以及细胞拖尾率、尾长、尾部DNA百分含量、尾矩的升高。p-p53比γ-H2AX和DNA链断裂指标在检测乙醛诱导的DNA损伤方面更加敏感。     

Aroclorl254预先染毒增强苯并[a]芘对Hep G2细胞DNA的损伤

目的 :探讨Hep G2细胞经Aroclor1254预处理后对苯并[a]芘诱发的DNA损伤的影响。 方法 :运用单细胞凝胶电泳技术检测了HepG2细胞经Aroclor1254(23、46、92和184μmol/L)单独染毒24h和将其预处理24h后再用苯并[a]芘染毒1h对DNA损伤的影响。 结果 :苯并[a]芘诱发的DNA损伤随着Aroclor1254预处理的浓度增大而升高 ,呈明显的剂量效应关系。当Aroclor1254预处理的浓度分别为46、92和184μmol/L时 ,苯并[a]芘诱发的DNA损伤与苯并[a]芘单独作用相比分别升高了8 %、16 %和160 %。184μmol/L的Aroclor1254预处理后 ,苯并[a]芘诱发的DNA损伤与苯并[a]芘单独作用相比有极显著性差异(P<0.01)。 结论 :Aroclor1254可显著地增强苯并[a]芘在HepG2细胞中诱导的DNA损伤 ,这种损伤的增强可能和Aro clor1254对Hep G2细胞CYP1A1的诱导有关。     

硒对丝裂霉素C致淋巴细胞遗传损伤的影响

背景与目的:观察硒对丝裂霉素C(mitomycin-C,MMC)诱导的人外周血淋巴细胞遗传损伤是否具有保护作用.材料与方法:在体外培养的淋巴细胞中,24 h时分别加入不同剂量的硒0、1、6和10 μmol/L,MMC 0和0.1 mg/L,培养72 h后,分别采用染色体畸变分析(CA)、姐妹染色单体互换技术(SCE),以及彗星试验(SCGE),对硒能否抑制MMC诱导的外周血淋巴细胞遗传损伤进行检测.结果:(1 μmol/L和6 μmol/L硒+MMC)组的淋巴细胞平均尾长、SCE互换率和CA畸变率低于阳性对照组,差异有统计学意义(P＜0.05).(6 μmol/:硒+MMC)组的DNA损伤程度低于(1 μmol/L硒+MMC)组和(10 μmol/L硒+MMC)组.结论:硒对MMC造成的人外周血淋巴细胞遗传损伤具有一定的保护作用,在本实验条件下,以6 μmol/L硒组的保护作用最强.     

三丁基锡引起人羊膜细胞氧化损伤及DNA损伤的研究

背景与目的： 研究三丁基锡 (tributyltin,TBT)对人羊膜细胞FL (human amnion cells) 氧化损伤和DNA损伤的诱导作用。 材料与方法： 将不同浓度TBT (0、2、4、6、8、10 μmol/L),分别对FL染毒2 h和4 h,各染毒组同时设不加TBT的对照组,染毒后分别用MTT法检测TBT对FL细胞增殖率的影响,用DCFH_DA法检测FL细胞活性氧自由基 (ROS)水平,用彗星实验检测TBT对FL细胞DNA的损伤。 结果： TBT对FL细胞染毒4 h时,其2、8、10 μmol/L浓度组的细胞增殖率较对照组显著下降(P<0.05,P<0.01,P<0.001),且随TBT浓度升高而增殖率呈下降的趋势。TBT 3、4 μmol/L染毒组FL细胞的ROS水平较对照组升高,且4 μmol/L染毒组与对照组比较差异具有统计学意义(P<0.05)。在TBT 2、3、4 μmol/L染毒组随着TBT浓度的升高,FL细胞核尾长、尾相均显著升高(P均<0.05)。 结论： TBT可引起FL细胞的氧化损伤及DNA损伤。     

Aroclor1254预先染毒增强苯并[a]芘对Hep G2细胞DNA的损伤

目的: 探讨Hep G2细胞经Aroclor1254预处理后对苯并[a]芘诱发的DNA损伤的影响. 方法: 运用单细胞凝胶电泳技术检测了Hep G2细胞经Aroclor1254(23、46、92和184 μmol / L)单独染毒24 h和将其预处理24 h后再用苯并[a]芘染毒1 h对DNA损伤的影响. 结果: 苯并[a]芘诱发的DNA损伤随着Aroclor1254预处理的浓度增大而升高,呈明显的剂量效应关系.当Aroclor1254预处理的浓度分别为46、92和184 μmol / L时,苯并[a]芘诱发的DNA损伤与苯并[a]芘单独作用相比分别升高了8 %、16 %和160 %.184 μmol / L的Aroclor1254预处理后,苯并[a]芘诱发的DNA损伤与苯并[a]芘单独作用相比有极显著性差异(P<0.01). 结论: Aroclor1254可显著地增强苯并[a]芘在Hep G2细胞中诱导的DNA损伤,这种损伤的增强可能和Aroclor1254对Hep G2细胞CYP1A1的诱导有关.     

大鼠一次性经皮染毒毒死蜱的毒代动力学和毒效应学研究

目的:研究大鼠一次性经皮染毒毒死蜱(CPF)的毒代动力学和毒效应学特征。方法:成年雌性SD大鼠按体质量随机分成3个剂量组(69.75、139.5、279 mg/kg)和1个对照组(0 mg/kg),皮下注射染毒,各组在给药后3、6、12、24、48、72 h共6个时间点收集大鼠血液和大脑皮质样本,在0～24、0～48和0～72 h连续收集尿液样本。测定指标包括血清CPF浓度,血清和尿液3,5,6-三氯-2-吡啶(TCP)浓度以及血清和大脑皮质乙酰胆碱酯酶(AChE)活性。结果:经皮染毒CPF剂量越大,大鼠血清CPF和TCP浓度越高,尿TCP排出量越大,血和皮质AChE活性抑制越大;血清CPF浓度在6 h达峰值,血清TCP浓度在12～24 h达峰值,血AChE活性在24 h最低,大脑皮质AChE活性在24～48 h最低。各剂量组血清CPF的半衰期为29～48 h,0～72 h曲线下面积(AUC)为31～110 h·μmol/L;血清TCP的半衰期为28～54 h,0～72 h AUC值为897～3 450 h·μmol/L。血AChE活性和大脑皮质AChE活性呈正相关(P<0.01),且血中的抑制率大于大脑皮质(P<0.01)。用DoseResp函数拟合血清CPF和AChE活性,呈现出剂量反应关系。结论:CPF外暴露剂量与大鼠体内CPF、TCP和AChE活性相关,内暴露水平和血AChE活性存在剂量效应关系;尿TCP排出量可作为机体暴露水平的生物标志;血AChE活性是大脑皮质AChE活性的有效生物标志。     

Expression of GADD153 in tumor cells and stromal cells from xenografted tumors in nude mice treated with cisplatin: correlations with cisplatin-DNA adducts

Purpose: Cisplatin is a commonly used antineoplastic agent that acts by forming adducts with DNA, and causing a response to the cellular injury. One of the components of this cellular injury response is the activation of the “growth arrest and DNA damage gene”GADD153. The level of GADD153 induction in tumor cells has been associated with the degree of cytotoxicity. The pupose of this study was to determine whether cisplatin activates GADD153 also in nontumor cells and how GADD153 protein levels correlate with cisplatin-DNA adducts in different cell types. Methods: Nude mice with xenografted squamous cell carcinoma were treated with cisplatin 10 mg/kg. Tumors were removed at 0 h (untreated controls), 24 h, and 48 h and immunohistochemically stained for GADD153 protein and cisplatin-DNA adducts. The staining reaction was quantitated in tumor cells and nonmalignant stromal cells separately, using computerized image analysis. Results: The GADD153 level was 4.5 times higher in tumor cells than in stromal cells in untreated mice. At 24 h after cisplatin treatment the GADD153 level had increased by 50% and 72% in tumor cells and stromal cells, respectively. Analysis of the cisplatin-DNA adducts showed a reversed pattern, with six-fold higher levels in stromal cells than in tumor cells at 24 h after treatment. By combining these data, we estimated that approximately 25-fold more GADD153 per cisplatin-DNA adduct was induced in tumor cells than in stromal cells. Conclusion: Our data suggest that different cell types may respond differently to DNA damage caused by cisplatin. Received: 5 March 1998 / Accepted: 21 July 1998     

全反式维甲酸对阿糖胞苷诱导HL-60细胞凋亡的影响

目的 :探讨 HL- 6 0细胞经全反式维甲酸 (ATRA)作用后对化疗药物阿糖胞苷 (Ara- C)诱导凋亡敏感性的变化。方法 :应用光镜检查凋亡细胞形态 ,DNA电泳检查梯状条带及流式细胞仪检测细胞周期分布、凋亡细胞率和 bcl- 2蛋白表达的阳性细胞率和相对荧光强度 (MFI)。结果 :ATRA0 .3mg/ L 作用 HL- 6 0细胞 72 h后 ,S期细胞显著减少至 32 .9% (P<0 .0 5 ) ,G0 / G1 期细胞明显增加达 5 8.5 % (P<0 .0 5 ) ,bcl- 2阳性细胞率和 MFI分别下降至 18%和 0 .6 3(P<0 .0 5 ) ;Ara- C1.5 m g/ L 作用 HL- 6 0细胞 4h,凋亡细胞率为 5 5 .1% ,DNA电泳见明显的梯状条带。当 HL- 6 0细胞经 ATRA0 .3m g/ L 作用 72 h后再加 Ara- C1.5 m g/ L 继续培养 4h,细胞凋亡率明显减少至 34 .4% (P<0 .0 5 ) ,DNA电泳见梯状条带亮度减弱。结论 :ATRA降低 HL- 6 0细胞对 Ara- C诱导凋亡敏感性 ,其机制可能与 ATRA阻滞 G0 / G1 期细胞进入 S期有关     

鸦胆子油对人肝癌细胞增殖的抑制作用及机制

目的:探讨鸦胆子油对人肝癌HepG2和Huh7细胞的增殖抑制作用及机制。方法:采用MTT法分析不同浓度鸦胆子油的增殖抑制作用,并用流式细胞仪进行细胞周期和细胞凋亡分析。结果:鸦胆子油能够使HepG2细胞和Huh7细胞的存活率降低,HepG2细胞24h和48h的IC50值分别为59.41μl/L和45.35μl/L,Huh7细胞24h和48h的IC50值为273.43μl/L和103.52μl/L。细胞周期实验中细胞G0/G1期比例升高。细胞凋亡实验中HepG2和Huh7细胞早期凋亡和晚期凋亡的比例均有增加,但晚期凋亡的细胞比例增加更大,分别为(61.47±7.74)%和(69.34±6.42)%。 结论:鸦胆子油能够抑制HepG2细胞和Huh7细胞的增殖,且通过阻滞细胞周期于G0/G1期诱导细胞凋亡。     

Induction of oxidative DNA damage by ferric iron in mammalian cells

Ferric nitrilotriacetate (Fe-NTA) and ferric citrate (Fe-citrate)were compared with respect to their potential to induce oxidativeDNA damage in V79 Chinese hamster cells. DNA base modifications,including 8-hydroxyguanine (7,8-dihydro-8-oxoguanine), werequantified by the frequency of lesions recognized by the bacterialFpg protein (formamidopyrimidine-DNA glycosylase) in combinationwith the alkaline unwinding assay. Fe-NTA induced oxidativeDNA damage in a time- and dose-dependent manner, yielding significantincreases in Fpg-sensitive sites above background after incubationfor 24 or 48 h with 500 and 250 µM respectively. At bothtime points the frequency of DNA base modifications exceededthe number of DNA strand breaks. In contrast, neither DNA strandbreaks nor Fpg-sensitive sites were detected after treatmentwith Fecitrate at concentrations up to 2 mM for 24 or 48 h;this inactivity of Fe-citrate was independent of the molar ratioof iron to ligand (1:1, 1:2, 1:10 or 1:20). The results indicatethat the cellular damage induced by ferric iron depends stronglyon the actual complex applied, possibly due to differences inthe intracellular distribution, which in turn may affect theavailability of iron for redox reactions at or in close proximityto the DNA.     

PM2.5对支气管上皮细胞DNA损伤作用研究

目的：探讨大气细颗粒物（PM_2.5）染毒对人支气管上皮细胞（HBE） DNA损伤的作用。方法：分别用8、20、50 μg/mL的PM_2.5水溶液染毒HBE细胞24 h后,单细胞凝胶电泳实验（SCGE）检测DNA损伤情况。10和50 μg/L的PM_2.5水溶液染毒HBE细胞,以未染毒细胞作为阴性对照组,10 μmol/L的Cr⁶⁺水溶液为阳性对照组,实时荧光定量PCR （qPCR）检测DNA损伤修复基因hOGG1、hMTH1的mRNA表达水平的变化,Western blot检测hOGG1、hMTH1蛋白表达变化。结果：单细胞凝胶电泳检测8、20和50 μg/mL PM_2.5水溶液染毒组HBE细胞的尾部DNA含量、尾长、尾距较阴性对照组明显增加（P < 0.05或P < 0.01）。qPCR结果显示,与阴性对照组比较,HBE细胞hOGG1 mRNA表达水平在10和50 μg/mL PM_2.5水溶液染毒以及阳性对照Cr⁶⁺水溶液染毒后分别升高75.0%、132.0%、214.0%;hMTH1 mRNA分别升高61.0%、144.0%、75.0%。Western blot结果显示,与阴性对照组比较,HBE细胞hOGG1蛋白表达水平在10和50 μg/mL PM_2.5水溶液染毒以及Cr⁶⁺水溶液染毒后分别升高47.6%、64.0%、47.0%;hMTH1蛋白分别升高20.5%、49.8%、20.9%。结论：PM_2.5水溶液染毒对HBE细胞DNA具有明显的损伤作用,并引起HBE细胞DNA损伤修复基因hOGG1、hMTH1表达水平升高。     

土贝母皂苷诱导人宫颈癌HeLa细胞周期阻滞和细胞凋亡

背景和目的：土贝母皂苷是由传统中药土贝母块茎中分离得到的,由土贝母苷甲（79%）和土贝母苷乙（21%）组成。本研究旨在探讨土贝母皂苷抗肿瘤作用的机制。方法：MTT法检测土贝母皂苷对肿瘤细胞生长的抑制作用,流式细胞仪分析细胞周期,荧光显微镜和电子显微镜观察细胞形态,琼脂糖凝胶电泳检测DNA电泳图谱的变化。结果：土贝母皂苷对人宫颈癌HeLa细胞的生长具有强制作用,且这种作用呈时间剂量依赖关系,处理24、48和72h的IC50值分别为20.0、18.8和8.8μmol/L.流式细胞术分析显示,15、30、35μmol/L土贝母皂苷处理5h,HeLa细胞G2/M期细胞数从9.80%分别增加到21.90%、25.92%和27.00%;处理12h,G2/M期细胞数增加更显著,从8.20%分别增加到21.40%、31.15%和34.55%。40μmol/L土贝母皂苷处理一定时间,形态学检查发现细胞核明显皱缩、核染色质凝集边聚等特征,流式细胞术检测发现凋亡峰,DNA琼脂糖凝胶电泳可见明显的梯形条带。结论：土贝母皂苷使细胞周期阻滞和诱导细胞凋亡可能在其抗肿瘤作用中具有重要意义。     

Effect of a Copper (II) Complex on The Induction of Apoptosis in Human Hepatocellular Carcinoma Cells

Objectives: In the present study, we aimed to identify the anti-proliferative potential of [Cu(L)(2imi)] complex[L = 2-(((5-chloro-2-oxyphenyl)imino)methyl)phenolato) and 2imi = 2-methyl imidazole] against HepG2 cells as anin vitro model of human hepatocellular carcinoma and normal mouse fibroblast L929 cells. Methods: The cytotoxicand apoptotic effects of [Cu(L)(2imi)] complex on HepG2 cells and normal fibroblasts (L929) were examined by MTTassay and flow cytometry, respectively. Results: Cytotoxicity induced by [Cu(L)(2imi)] complex was time dependent.Also, there was a positive correlation between cytotoxicity and an increase in Cu complex concentration. For HepG2cells, the cell viability percentage was 50% at 58 μg/mL after 24 h treatment, whereas in the same concentration andconditions, the viability percentage was surprisingly higher (about 100%) for L929 cells. Also, after 48 h treatment,the viability percentage of HepG2 cells at 55 μg/mL concentration was 50% in contrast with 89.3% for L929 cells inthe same conditions. Flow cytometry findings suggest that [Cu(L)(2imi)] complex is capable of decreasing cancer cellviability through apoptosis and did not efficiently activate the necrosis process. Conclusions: Finally, we found that[Cu(L)(2imi)] complex possess the potential for development as an anti-cancer drug for human hepatocellular carcinoma.     

Multiple effects of 3-aminobenzamide on DNA damage induced by cisplatin (DDP) in DDP-sensitive and -resistant rat ovarian tumor cell lines.

To investigate the mechanisms by which 3-aminobenzamide (3AB) reverses cisplatin (DDP) resistance in a rat ovarian tumor cell line, the effects of 3AB on DDP-induced DNA damage and repair were kinetically determined over a post-exposure period of 48 h. DNA single strand breaks (SSB) occurred maximally 12 h and 24 h following DDP exposure in DDP-resistant (O-342/DDP) and -sensitive (O-342) rat ovarian tumor cells, respectively. 3AB, present during and after the exposure, significantly increased SSB formation by DDP at 24 h (P < 0.02) and 48 h (P < 0.01) in O-342/DDP cells. To a lesser extent (P > 0.05), a similar tendency was also observed in O-342 cells. Formation of DNA interstrand cross-links (ISCL) by DDP reached a maximum by 12 h in either O-342 or O-342/DDP cells, but in the resistant cells they were both much lower and more rapidly removed. 3AB decreased ISCL in the sensitive cells at 12 h and thereafter with a maximum at 24 h (P < 0.05), while in the resistant cells the same treatment decreased ISCL at 12 h, had no effect at 24 h and increased ISCL at 48 h following DDP treatment. Therefore, it is concluded that 3AB has multiple effects on DNA damage and repair induced by DDP in both cell lines and increase of DNA-ISCL by 3AB at 48 h after the exposure in O-342/DDP cells might be related to its chemosensitizing effect in this line.     

DNA adduct formation in mice treated with ochratoxin A.

Several authors have reported the occurrence of renal and hepatic tumours in mice and rats exposed to ochratoxin A in long-term studies. The compound was not mutagenic, however, in various microbial and mammalian gene mutation assays, either with or without metabolic activation. Contradictory results were obtained for induction of unscheduled DNA synthesis and sister chromatid exchange. We showed previously that ochratoxin A causes DNA damage, manifested as single-strand breaks in mouse spleen cells and in vivo. These findings, which suggest that ochratoxin A is weakly genotoxic to mammalian cells, prompted us to search for DNA adducts using a modified 32P-postlabelling method, the sensitivity of which was improved by treatment with nuclease P1. DNA was isolated from liver, kidney and spleen excised from mice 24, 48 and 72 h after oral treatment with ochratoxin A at 0.6, 1.2 and 2.5 mg/kg body weight. Several adducts were found in the DNA of the three organs, the levels varying greatly. After administration of 2.5 mg/kg body weight, 40 adducts per 10(9) nucleotides were found in kidney DNA and 7 adducts per 10(9) nucleotides in liver after 72 h. The levels of most of the adducts increased from 24 to 72 h, but those of others diminished after 24 or 48 h. Adducts were found in spleen only at 24 and 48 h. These results confirm the genotoxicity of ochratoxin A.