Anticancer Drug Resistance of HeLa Cells Transfected With Rat Glutathione S-transferase pi Gene

Objective To establish a cytologic expressing system of rat glutathione S-transferase pi (GST-pi) cDNA for detecting the resistance of HeLa cells to anticancer drugs. Methods The assessment was made with various anticancer drugs (adriamycin, mitomycin, cisplatinum and vincristine) that showed different cytotoxicities in transfectant HeLa cells with pSV-GT containing rat GST-pi cDNA (HeLa/pSV-GT) or control pSV-neo (HeLa/pSV-neo). Expression levels of GST-pi mRNA in HeLa/pSV-GT and HeLa/pSV-neo were measured by in situ hybridization using Digoxin-labelled cDNA probe. Results HeLa/pSV-GT expressed significantly high degree of GST-pi mRNA, whereas both HeLa/pSV-neo and HeLa cells had very low expression. Cytotoxicities of HeLa/pSV-GT and HeLa/pSV-neo with 4 anticancer drugs were measured by MTT assay. Drug concentrations for yielding 50% inhibition (IC50) in HeLa/pSV-GT by adriamycin, mitomycin and cisplatinum were 70.13μg/mL, 10.95μg/mL and 16.52μg/mE respectively. In contrast, IC50 in HeLa/pSV-neo was 10.34μg/mL, 7.48μg/mL and 13.70μg/mE respectively. The cytotoxicities of vincristine on both HeLa/pSV-GT and HeLa/pSV-neo were not significantly different. Conclusions Our findings suggest that HeLa/pSV-GT containing rat GST-pi cDNA is resistant to some anticancer drugs due to overexpression of GST-pi. Also, HeLa/pSV-GT cell line could serve as a useful cytogenetic model for further research.     

Responses of antioxidant systems in the hepatocytes of common carp (Cyprinus carpio L.) to the toxicity of microcystin-LR.

The freshwater, bloom-forming cyanobacterium (blue-green alga) Microcystis aeruginosa produces a peptide hepatotoxin, which causes the damage of animal liver. Recently, toxic Microcystis blooms frequently occur in the eutrophic Dianchi Lake (300 km2 and located in the South-Western of China). Microcystin-LR from Microcystis in Dianchi was isolated and purified by high performance liquid chromatography (HPLC) and its toxicity to mouse and fish liver was studied (Li et al., 2001). In this study, six biochemical parameters (reactive oxygen species, glutathione, superoxide dismutase, catalase, glutathione peroxide and glutathione S-transferase) were determined in common carp hepatocytes when the cells were exposed to 10 microg microcystin-LR per litre. The results showed that reactive oxygen species (ROS) contents increased by more than one-time compared with the control after 6 h exposure to the toxin. In contrast, glutathione (GSH) levels in the hepatocytes exposed to microcystin-LR decreased by 47% compared with the control. The activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxide (GSH-Px) increased significantly after 6 h exposure to microcystin-LR, but glutathione S-transferase (GST) activity showed no difference from the control. These results suggested that the toxicity of microcystin-LR caused the increase of ROS contents and the depletion of GSH in hepatocytes exposed to the toxin and these changes led to oxidant shock in hepatocytes. Increases of SOD, CAT and GSH-Px activities revealed that these three kinds of antioxidant enzymes might play important roles in eliminating the excessive ROS. This paper also examined the possible toxicity mechanism of microcystin-LR on the fish hepatocytes and the results were similar to those with mouse hepatocytes.     

The use of Lepidium sativum in a plant bioassay system for the detection of microcystin-LR.

Toxin-producing cyanobacteria pose a worldwide health threat to humans and animals due to their increasing presence in both drinking and recreational waters. Detection of microcystins in water generally relies on specialised equipment and a delay of several days for transport and analysis. Little work has, however, been done on establishing a simple, cost-effective and sensitive plant bioassay for the detection of microcystin-LR (MCLR) in water at the WHO Tolerable Daily Intake guideline level of 1 microg/l. We investigated the effect of a MCLR extract at 1 and 10 microg/l on the growth of Lepidium sativum over 6 days. Exposure to 10 microg/l MCLR resulted in a significant decrease in root and leaf lengths and fresh weights of seedlings when compared to the controls. These results were consistent with seedlings exposed to pure MCLR at 10 microg/l. Seedlings exposed to 1 microg/l MCLR showed a significant decrease in root development from day 2 to day 6. Glutathione S-transferase and glutathione peroxidase activities were also significantly raised in plants from days 5 and 4, respectively, at both toxin levels investigated.     

GSTM1、GSTT1基因多态性和饮酒习惯与原发性肝癌发生的危险性

目的　研究GSTM 1和GSTT 1基因的多态性和饮酒习惯与原发性肝癌发生的危险性。方法　在肝癌高发区江苏省泰兴市进行了以人群为基础的病例对照研究 ,并应用多重PCR法检测了 2 0 7例原发性肝癌及其 1∶1配对的正常对照的GSTM 1和GSTT 1基因型。结果　GSTM 1空白基因型的频率 ,病例组为 5 8.94% ,对照组为 5 7.0 0 % ;GSTT 1空白基因型的频率 ,病例组和对照组分别为 5 2 .17%和 46.86% ,2组间无显著性差异。但GSTT 1的空白基因型与非空白基因型相比 ,当其长期饮用高度白酒达2 3年以上或月饮酒量大于 3 0 0 0 g时 ,患肝癌的危险性显著增高 (OR =2 .5 6,95 %CI为 1.0 8～ 6.0 5或OR =3 .48,95 %CI为 3 1.47～ 8.2 2 ) ;此外分析饮酒总量 (kg·年 )也得到同样的结果 (OR =3 .71,95 %为 1.5 1～ 9.12 )。结论　携带GSTT 1空白基因型且有长期大量饮酒习惯者 ,其患肝癌的危险性显著增高     

GENETIC DELETION OF DETOXIFIC ENZYME GSTM1 AND GSTTI AS A HOST SUSCEPTIBLE FACTOR FOR NASOPHARYNGEAL CARCINOMA

Objective: To study the gene polymorphisms of GSTT1 and GSTM1 in nasopharyngeal carcinoma (NPC) patients and controls in an incidental area to evaluate the relationship between specific genotype and genotype combinations of these polymorphisms with the risk of NPC. Methods: Cases and controls all came from the Southwestern Guangxi. DNAs were extracted from their WBC. PCR technique was used to calculate the deletion rate of the two detoxific enzyme genes. Results: In this high risk area of NPC, the residents had high level deletion rates of 47.4% (64/135) Ml and T1 40.7% (55/135). The deletion rates were even higher in NPC patients, 61.5% (56/91) for Ml and 59.3% (54/91) for T1 respectively. There were statistical significances compared with control,P<0.05 andP<0.01 for Ml and T1 respectively. The difference was more significant in terms of combined Ml and T1 deletion between patients and controlsx ²=12.533,P=0.002. Conclusion: The combined deletion of detoxific enzyme genes GSTM1 and GSTT1 may be an important genetic susceptible factor for NPC in Guangxi. Biography: DENG Zhuo-lin (1929-), male, professor of pathology, Guangxi Medical University, majors in tumor pathology. E-mail :zhuolin@hotmail.com     

Influence of different hemodialysis membranes on red blood cell susceptibility to oxidative stress

Oxidative stress is crucial in red blood cell (RBC) damage induced by activated neutrophils in in vitro experiments. The aim of the study was to evaluate whether the bioincompatibility phenomena occurring during hemodialysis (HD) (where neutrophil activation with increased free radical production is well documented) may have detrimental effects on RBC. We evaluated RBC susceptibility to oxidative stress before and after HD in 15 patients using Cuprophan, cellulose triacetate, and polysulfone membrane. RBC were incubated with t-butyl hydroperoxide as an oxidizing agent both in the presence and in the absence of the catalase inhibitor sodium azide. The level of malonaldehyde (MDA), a product of lipid peroxidation, was measured at 0, 5, 10, 15, and 30 min of incubation. When Cuprophan membrane was used, the MDA production was significantly higher after HD, indicating an increased susceptibility to oxidative stress in comparison to pre-HD. The addition of sodium azide enhanced this phenomenon. Both cellulose triacetate and polysulfone membranes did not significantly influence RBC susceptibility to oxidative stress. Neither the level of RBC reduced glutathione nor the RBC glutathione redox ratio changed significantly during HD with any of the membranes used. The RBC susceptibility to oxidative stress was influenced in different ways according to the dialysis membrane used, being increased only when using the more bioincompatible membrane Cuprophan, where neutrophil activation with increased free radical production is well documented. The alterations found in this study might contribute to the reduced RBC longevity of HD patients where a bioincompatible membrane is used.     

谷胱苷肽转移酶抑制剂高通量筛选模型的建立和初步应用

谷胱苷肽 - S-转移酶 -π( GST-π)的活性在某些类型的癌症患者中有显著的升高并且在癌症细胞对抗癌药物抗药性的形成过程中起着重要的作用。抑制过量表达的 GST-π酶的活性将有助于克服肿瘤细胞的耐药性 ,因此 ,GST-π被认为是一个潜在的药物作用的靶位点。为了筛选新的抗癌药物的增敏剂 ,我们建立了一个 GST-π酶抑制剂的高通量筛选模型 ,该模型以 CDNB和 GSH为底物 ,在 96 -孔板上通过对 340 nm处吸光度的变化来检测样品对 GST-π酶的抑制活性。经过初筛和复筛 ,从 4 80 0个微生物发酵提取物中筛选到10个阳性样品 ,阳性率为 0 .2 %。     

肺癌核素显像与Pgp、PCNA、GST-π关系的初步研究

目的：探讨肺癌核素显像＾９９ｍＴｃ－ＭＩＢＩ滞留分数与Ｐ糖蛋白（Ｐｇｐ）、增殖细胞核抗原（ＰＣＮＡ）和胎盘型谷胱甘肽－Ｓ－转移酶（ＧＳＴ－π）的关系。方法：１２例肺癌病人术前分别作肺部早期和延迟＾９９ｍＴｃ－ＭＩＢＩ断层显像,计算肿瘤部位＾９９ｍＴｃ－ＭＩＢＩ滞留分数,与手术后肿瘤标本测定的Ｐｇｐ、ＰＣＮＡ、ＧＳＴ－π水平作相关分析。结果：＾９９ｍＴｃ－ＭＩＢＩ滞留分数与Ｐｇｐ明显负相关（ｒ＝－０     

肺癌患者红细胞内谷胱甘肽的含量与临床疗效的相关性

目的与方法利用分光光度法,对33例肺癌患者及43例正常人红细胞内谷光甘肽（GSH）的含量进行测定,并与临床近期疗效的关系进行比较。结果肺癌患者治疗前后的GSH值与正常人之间有显著性差异（P＜0.05）。25例可观察近期疗效的患者中,有效者8例,其治疗前后的GSH及其与正常人之间无显著性差异（P＞0.1）;而治疗无效者17例,其治疗前后的GSH有显著性差异（P＜0.05）,与正常人之间有非常显著性差异（P＜0.01）。有转移与无转移患者治疗前GSH有显著性差异（P＜0.05）。且患者治疗前GSH高,临床治疗无效与治疗前GSH低临床治疗有效的总符合率为6667％（16／25）。结论肺癌患者GSH的高低与患者的有无转移及治疗预后密切相关,即GSH高治疗有效率低,GSH低治疗有效率高,预后好。     

EFFECTS OF COMBINATION OF ACUPUNCTURE AND MOXIBUSTION WITH CHINESE DRUGS ON LIPIDS PEROXIDE AND ANTIOXIDASE IN PATIENTS OF VASCULAR DEMENTIA

Withincreaseofincidenceofcerebrovascu-lardiseases,thepatientsofVDincreasedaybyday.Inrecentyearsithasbeenindicatedthatacupuncture,moxibustionandChinesedrugshavedefinitetherapeuticeffectsforVDL1].Inordertoprobeintothetherapeuticmechanism,inthepresentexperim…