人细胞色素p450IA2基因的构建及其功能检测：——该基因在啮齿类细胞中代谢活

本文首先构建了含人类细胞色素ｐ４５０ＩＡ２ｃＤＮＡ的ｐＺｉｐ－ｐ４５０ＩＡ２的真核表达载体，并分别将其转染到Ｖ７９细胞和原代大鼠肝上皮细胞中，Ｎｏｒｔｈｃｎ杂交和免疫组化实验显示，Ｖ７９转染细胞中有人ｐ４５０ＩＡ２的ＲＮＡ和蛋白水平的表达。细胞毒实验和ＨＧＰＲＴ位点突变率检测结果证明，外源性ｐ４５０ＩＡ２基因可在Ｖ７９细胞中代 谢活化黄曲霉毒素Ｂ１。转染有ｐＺｉｐ－ｐ４５０ＩＡ２质粒的原代大鼠肝细     

逆转录病毒介导人细胞色素p450IA＿2cDNA在V79细胞中稳定表达及其代谢活化黄曲霉毒素B＿1

逆转录病毒介导人细胞色素ｐ４５０ＩＡ＿２ｃＤＮＡ在Ｖ７９细胞中稳定表达及其代谢活化黄曲霉毒素Ｂ＿１袁宝珠，孙宗棠目前认为黄曲霉毒素Ｂ１（ＡｆｌａｔｏｘｉｎＢ１，ＡＦＢ１）是肝细胞致癌剂，它经肝细胞内微粒体细胞色素ｐ４５０代谢活化成最终致癌剂。为了加强...     

人c－myc基因辅助黄曲霉毒素B1体外转化大鼠肝上皮细胞

人ｃ－ｍｙｃ基因辅助黄曲霉毒素Ｂ１体外转化大鼠肝上皮细胞袁宝珠，孙宗棠我们利用基因转染技术，探索黄曲霉毒素Ｂ１（ＡＦＢ１）在人ｃ－ｍｙｃ基因辅助下，转化体外原代大鼠肝上皮细胞的可能性。首先，我们利用ＥｃｏＲＩ和ＫｐｎＩ将人ｃ－ｍｙｃ基因从ｐＢＲ３２２...     

腺病毒介导的p53基因对喉癌细胞生长的抑制作用

目的探索ｐ５３基因在喉癌基因治疗方面的可行性。方法以人喉癌细胞系Ｈｅｐ－２为实验对象,将载有人野生型ｐ５３ｃＤＮＡ并含巨细胞病毒（ＣＭＶ）启动子的重组腺病毒（Ａｄ５ＣＭＶ－ｐ５３）感染Ｈｅｐ－２细胞及肿瘤组织,体内外实验观察Ａｄ５ＣＭＶ－ｐ５３对Ｈｅｐ－２细胞生长的影响。结果当Ａｄ５ＣＭＶ－ｐ５３在１００ＭＯＩ效靶比时,全部Ｈｅｐ－２细胞得到转染。感染２天后ｐ５３蛋白表达达到高峰,Ｈｅｐ－２生长受到明显的抑制。Ａｄ５ＣＭＶ－ｐ５３感染Ｈｅｐ－２细胞在裸鼠中失去致瘤性。瘤内注射Ａｄ５ＣＭＶ－ｐ５３后,荷瘤裸鼠的肿瘤体积明显减小。结论Ａｄ５ＣＭＶ－ｐ５３转导野生型ｐ５３基因可能是一种有效的喉癌基因治疗途径。     

三氧化二砷诱导人类B细胞性淋巴瘤细胞凋亡及机制探讨

目的 研究Ａｓ２Ｏ３在体外对人类Ｂ淋巴瘤细胞株ＭＢＣ－１细胞增殖的影响，并探讨其作用机制。方法 采用细胞形态学，ＤＮＡ凝胶电泳，流式细胞术等多参数观察。结果 （１）（０．５～２）ｍＭ／Ｌ，Ａｓ２Ｏ３对ＭＢＣ－１细胞有增殖抑制作用，并呈时间和剂量相关，（２）证实诱导细胞凋亡是Ａｓ２Ｏ３增殖抑制作用的主要机制之一；（３）Ａｓ２Ｏ３能够上调ＭＢＣ－１细胞ｐ５３的蛋白表达，结论Ａｓ２Ｏ３能有效地通过诱导人     

三氧化二砷诱导人类B细胞性淋巴瘤细胞凋亡及机制探讨

目的研究Ａｓ２Ｏ３在体外对人类Ｂ淋巴瘤细胞株ＭＢＣ－１细胞增殖的影响,并探讨其作用机制。方法采用细胞形态学、ＤＮＡ凝胶电泳、流式细胞术等多参数观察。结果（１）（０．５～２）ｍＭ／ＬＡｓ２Ｏ３对ＭＢＣ－１细胞有增殖抑制作用,并呈时间和剂量相关;（２）证实诱导细胞凋亡是Ａｓ２Ｏ３增殖抑制作用的主要机制之一;（３）Ａｓ２Ｏ３能够上调ＭＢＣ－１细胞ｐ５３的蛋白表达。结论Ａｓ２Ｏ３能有效地通过诱导人类Ｂ淋巴瘤细胞株ＭＢＣ－１细胞凋亡而起到增殖抑制作用,而ｐ５３基因可能参与了对该凋亡过程的调控。     

AnnexinI基因转染对BEP2D细胞生长的影响

研究ＡｎｎｅｘｉｎⅠ基因ｃＤＮＡ转染对生化人支气管细胞系ＢＥＰ２Ｄ生长的影响。方法：ｐＴ７Ｔ３Ｄ质粒经ＮｏｔⅠ和ＸｈｏⅠ双酶切获得 人ＡｎｎｅｘｉｎⅠ基因ｃＤＮＡ片段，亚克隆至真核表达载体ｐＣＩ－ｎｅｏ，构建人ＡｎｎｅｘｉｎⅠ基因真核表达载体ｐＣＩ－ＡＸＩ。通过采用脂质体介导转染技术，将ＡｎｎｅｘｉｎⅠ的真核表达重组质粒和空载体质粒分别导入永生化人支气管管细胞系ＢＥＰ２Ｄ；合成ＡｎｎｅｘｉⅠ反应寡     

CYP2B6cDNA导入V79、FL和CHL细胞中稳定表达及其初步鉴定

ＣＹＰ２Ｂ６ｃＤＮＡ导入Ｖ７９、ＦＬ和ＣＨＬ细胞中稳定表达及其初步鉴定吴健敏，董海涛，余应年，朱丽君（浙江医科大学病理生理学教研室及医学分子生物学实验室杭州３１００３１）细胞色素Ｐ４５０是代谢活化大多数前致突变物／致癌物的主要酶系，在建株细胞中这些基...     

番荔枝内酯化合物squamocin诱导白血病HL-60细胞凋亡

目的：研究番荔枝内酯化合物ｓｑｕａｍｏｃｉｎ诱导白血病ＨＬ－６０细胞凋亡作用。方法：采用ＭＴＴ法检测番荔枝内酯单体化合物ｓｑｕａｍｏｃｉｎ对白血病细胞株ＩＬ－６０细胞增殖的抑制作用;ＤＮＡ凝胶电泳检测细胞凋亡;Ｗｅｓｔｅｒｎ ｂｌｏｔ法检测ｂｃｌ－２,ｂａｘ,ｐ２１＾ＷＡＦ１,磷酸化ｐ４４／４２ ＭＡＰＫ的蛋白水平变化。结果：ｓｑｕａｍｏｃｉｎ处理ＨＬ－６０细胞５天后,细胞生长受到明显的抑制,ＩＣ５０为０．１７μｇ／ｍｌ。ＤＮＡ凝胶电泳可见典型的ＤＮＡ梯形带。ｓｑｕａｍｏｃｉｎ处理ＨＬ－６０细胞后,Ｗｅｓｔｅｒｎ ｂｌｏｔ检测结果呈现ｂｃｌ－２,ｂａｘ,ｐ２１＾ＷＡＦ１蛋白表达无明显变化,而磷酸化的ＭＡＰＫ量显著减少。结论：ｓｑｕａｍｏｃｉｎ能诱导ＨＬ－６０细胞凋亡,且与ｂｃｌ－２、ｂａｘ、ｐ２１＾ＷＡＦ１蛋白     

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－６０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－６０细胞７２ｈ后,Ｓ期细胞显著减少至３２．９％（Ｐ〈０．０５）,Ｇ０／Ｇ１期细胞明显增加到５８．５％（Ｐ〈０．０５）,ｂｃｌ－２阳性细胞率和ＭＦＩ分别下降至１８％和０．６３（Ｐ〈０．０５）;Ａｒａ－Ｃ１．５ｍｇ／Ｌ作用ＨＬ－６０细胞４ｈ,凋亡细胞率为５５．１％,ＤＮＡ电泳风明显的梯状条带。当ＨＬ－６０细胞经ＡＴＲＡ０．３ｍｇ／Ｌ作用７２ｈ手中Ａｒａ－Ｃ１．５ｍｇ／Ｌ继续培养４ｈ,细胞凋亡率明显减少至３４．４％（Ｐ〈０．０５）,     

Expression of stably transfected murine glutathione S-transferase A3-3 protects against nucleic acid alkylation and cytotoxicity by aflatoxin B1 in hamster V79 cells expressing rat cytochrome P450-2B1.

Aflatoxin B1 (AFB1) is activated to AFB1-8,9-oxide (AFBO), a potent mutagenic and carcinogenic metabolite of AFB1. In the mouse, AFBO has been shown to be most efficiently detoxified by a specific isozyme of alpha-class glutathione S-transferase (GST), mGSTA3-3 (mGST-Yc). A hamster V79 cell line (V79MZr2B1, originally designated V79/SD1) previously transfected with the rat cytochrome P450-2B1 was stably transfected with an mGSTA3-3 expression vector, to study the chemopreventive role of GST in protecting against cytotoxicity or genotoxicity of AFBO. Immunoblotting demonstrated strong expression of an alpha-class GST in the mGSTA3-3 transfected cell line, whereas no detectable alpha-class GST protein was observed in the control (empty vector-transfected) cells. Previous studies with the V79MZr2B1 cell line indicated that it can activate AFB1 to a mutagenic metabolite via a transfected rat P450-2B1 stably expressed in the cells. We examined the ability of the expressed mGSTA3-3 to protect against AFB1-induced cytotoxicity or [3H]-covalent adduct formation in cellular nucleic acids. Exposure of empty vector-transfected control cells and mGSTA3-3 expressing cells to up to 600 nM [3H]-AFB1 indicated that a 70-80% reduction in DNA and RNA adducts was afforded by the expression of mGSTA3-3 in the transfected cells. Clonogenic survival assays showed that the mGSTA3-3 cell line was 4.6-fold resistant to AFB1 cytotoxicity as compared with the empty vector-transfected control SD1 cells, with IC50 values of 69 and 15 microM, respectively. The results of these studies demonstrate that mGSTA3-3 confers substantial protection against nucleic acid covalent modification and cytotoxicity by AFB1 in this transgenic cell model system.     

Stable expression of rat cytochrome P450IA2 cDNA and hydroxylation of 17 beta-estradiol and 2-aminofluorene in V79 Chinese hamster cells.

In continuation of our work toward the establishment of a working cell bank for metabolic and toxicological studies, V79 Chinese hamster cells were genetically engineered for stable expression of rat cytochrome P450IA2. Full-length cDNA encoding rat P450IA2 was obtained by searching a cDNA library made from Aroclor 1254-induced rat liver mRNA and by joining a small 5'-end fragment to a fragment containing the rest of the cDNA. The sequence of the cDNA was confirmed by DNA sequencing and comparison to a previously published cDNA sequence. The reconstructed full-length cDNA was inserted into a simian virus 40 early promoter-containing eukaryotic expression vector and cotransferred with the neomycin phosphotransferase gene as a selective marker into V79 cells by the calcium/phosphate-coprecipitation technique. G418-resistant V79 cell clones were checked for chromosomal integration of the cDNA by Southern blotting, for expression of authentic mRNA and protein by northern and western blotting, and for P450IA2-specific enzymatic activities such as hydroxylation of 17 beta-estradiol and 2-aminofluorene.     

Aflatoxin B1-induced DNA adduct formation and p53 mutations in CYP450- expressing human liver cell lines

Epidemiological evidence has been supporting a relationship between dietary aflatoxin B1 (AFB1) exposure, development of human primary hepatocellular carcinoma (HCC) and mutations in the p53 tumor suppressor gene. However, the correlation between the observed p53 mutations, the AFB1 DNA adducts and their activation pathways has not been elucidated. Development of relevant cellular in vitro models, taking into account species and tissue specificity, could significantly contribute to the knowledge of cytotoxicity and genotoxicity mechanisms of chemical procarcinogens, such as AFB1, in humans. For this purpose a non-tumorigenic SV40-immortalized human liver epithelial cell line (THLE cells) which retained most of the phase II enzymes, but had markedly reduced phase I activities was used for stable expression of the human CYP1A2, CYP2A6, CYP2B6 and CYP3A4 cDNA. The four genetically engineered cell lines (T5-1A2, T5-2A6, T5-2B6 and T5-3A4) produced high levels of the specific CYP450 proteins and showed comparable or higher catalytic activities related to the CYP450 expression when compared to human hepatocytes. The T5-1A2, T5-2A6, T5-2B6 and T5-3A4 cell lines exhibited a very high sensitivity to the cytotoxic effects of AFB1 and were approximately 125-, 2-, 2- and 15-fold, respectively, more sensitive than the control T5-neo cells, transfected with an expressing vector which does not contain CYP450 cDNA. In the CYP450-expressing cells, nanomolar doses of AFB1-induced DNA adduct formation including AFB1-N7-guanine, -pyrimidyl and -diol adducts. In addition, the T5-1A2 cells showed AFM1-DNA adducts. At similar levels of total DNA adducts, both the T5-1A2 and T5-3A4 cells showed, at codon 249 of the p53 gene, AGG to AGT transversions at a relative frequency of 15x10(-6). In contrast, only the T5-3A4 cells showed CCC to ACC transversion at codon 250 at a high frequency, whereas the second most frequent mutations found in the T5-1A2 cells were C to T transitions at the first and second position of the codon 250. No significant AFB1-induced p53 mutations could be detected in the T5-2A6 cells. Therefore, the differential expression of specific CYP450 genes in human hepatocytes can modulate the cytotoxicity, DNA adduct levels and frequency of p53 mutations produced by AFB1.      

Comparative ultrastructural effects of aflatoxin B1 on mouse, rat, and human hepatocytes in primary culture

Human, rat, and mouse hepatocytes in primary culture were treated with aflatoxin B1 (AFB1) and examined for ultrastructural alterations. As early as 1 h following in vitro exposure to AFB1, there were ultrastructural changes in the nuclei of rat and human hepatocytes. The most prominent change in the nuclei was a segregation of nucleolar components that resembled the segregation in liver cells of rats exposed to AFB1 in vivo. The nucleolar segregations were developed by incubating rat hepatocytes for 24 h in a medium containing as little as 0.01 micrograms of AFB1 per ml. The minimum concentration to induce the same change in human hepatocytes was 0.1 micrograms/ml. No distinct nucleolar alteration was observed in mouse hepatocytes incubated in a medium containing 10 micrograms of AFB1 per ml. Irregular nuclear chromatin condensation also developed in the cells exposed to a higher concentration of AFB1, whereas little damage was observed in mitochondria and lysosomes. The similarity in morphological changes between our in vitro model and in vivo models previously investigated indicates that the hepatocytes in primary culture maintain the biological properties necessary for carcinogen responses similar to liver cells in vivo. In addition, the morphological changes in cultured rat and mouse hepatocytes induced by AFB1 correlate with in vivo experiments insofar as mice are relatively resistant, whereas rats are sensitive to AFB1 carcinogenesis. Thus, cultured hepatocyte systems may be a valuable tool to study genetic damage which may lead to hepatocellular carcinomas in human and animal livers.     

Identification of differentially expressed genes in aflatoxin B1- treated cultured primary rat hepatocytes and Fischer 344 rats

Aflatoxin B1 (AFB1), a mutagen and hepatocarcinogen in rats and humans, is a contaminant of the human food supply, particularly in parts of Africa and Asia. AFB1-induced changes in gene expression may play a part in the development of the toxic, immunosuppressive and carcinogenic properties of this fungal metabolite. An understanding of the-role of AFB1 in modulating gene regulation should provide insight regarding mechanisms of AFB1-induced carcinogenesis. We used three PCR- based subtractive techniques to identify AFB1-responsive genes in cultured primary rat hepatocyte RNA: differential display PCR (DD-PCR), representational difference analysis (RDA) and suppression subtractive hybridization (SSH). Each of the three techniques identified AFB1- responsive genes, although no individual cDNA was isolated by more than one technique. Nine cDNAs isolated using DD-PCR, RDA or SSH were found to represent eight genes that are differentially expressed as a result of AFB1 exposure. Genes whose mRNA levels were increased in cultured primary rat hepatocytes after AFB1 treatment were corticosteroid binding globulin (CBG), cytochrome P450 4F1 (CYP4F1), alpha-2 microglobulin, C4b-binding protein (C4BP), serum amyloid A-2 and glutathione S-transferase Yb2 (GST). Transferrin and a small CYP3A-like cDNA had reduced mRNA levels after AFB1 exposure. Full-length CYP3A mRNA levels were increased. When liver RNA from AFB1-treated male F344 rats was evaluated for transferrin, CBG, GST, CYP3A and CYP4F1 expression, a decrease in transferrin mRNA and an increase in CBG, GST, CYP3A and CYP4F1 mRNA levels was also seen. Analysis of the potential function of these genes in maintaining cellular homeostasis suggests that their differential expression could contribute to the toxicity associated with AFB1 exposure.      

Kinds of mutations induced by aflatoxin B1 in a shuttle vector replicating in human cells transiently expressing cytochrome P4501A2 cDNA.

Transient expression of rat liver cytochrome P450lA2 cDNA was combined with the use of a shuttle vector as a mutational target to determine the frequency and types of mutation caused by the conversion of aflatoxin B1 into genotoxic metabolites within human cells. Ad293 cells were first transfected with p91-lA2, a rat liver P450lA2 cDNA expression vector, or with p91-lA2(i) (a control vector that has the P450 cDNA in the inverted orientation) and incubated for 24 h to permit P450lA2 accumulation. Cells were then transfected with the pS189 shuttle-vector plasmid, which carries the Escherichia coli supF gene as a mutational target, and incubated for a further 24 h in the presence of aflatoxin B1 to permit promutagen activation and pS189 replication. In shuttle vectors replicated in p91-lA2-transfected cells, the supF point-mutation frequency increased with increasing concentration of aflatoxin B1. This frequency was nine to 23 times greater than the background point-mutation frequency obtained with aflatoxin B1-treated control (p91-lA2(i)-transfected) cells. The large majority of the aflatoxin B1-induced supF point mutations were base substitutions, mostly G:C----T:A transversions. This mutagenesis system permits the molecular analysis of mutations induced by specific P450/promutagen pairs in a shuttle vector replicating in human cells and will permit the investigation of host cell mechanisms involved in the generation of these mutations.     

2-Amino-3,4-dimethylimidazo[4,5-f]quinoline induces and inhibits cytochrome P450 from the IA subfamily in chick and rat hepatocytes.

Several heterocyclic amines, found in cooked food, are powerful mutagens in the Ames Salmonella mutagenicity test system. One of these, 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ) is one of the most mutagenic chemicals tested in this assay. In primary cultures of chick and rat hepatocytes, MeIQ, by itself, induced cytochrome P450 from the IA subfamily but was a weak inducer compared to 3-methylcholanthrene. However, in both chick and rat hepatocytes in culture, MeIQ decreased the amount of 3-methylcholanthrene-induced ethoxyresorufin deethylase activity, which is catalyzed by cytochrome P450 IA. The protein moiety of cytochrome P450 IA was decreased at MeIQ concentrations of 2.5 micrograms/ml or greater in chick hepatocytes and 25 micrograms/ml in rat hepatocytes. In hepatic microsomes from methylcholanthrene-treated chicks and rats, MeIQ was a competitive inhibitor of both ethoxyresorufin deethylase activity, a reaction catalyzed mainly by rodent cytochrome P450 IA1, and uroporphyrinogen oxidation, a reaction catalyzed by rodent P450 IA2. In cultured chick hepatocytes, MeIQ also decreased cytochrome P450-mediated oxidation of uroporphyrinogen by intact cells. The ability of MeIQ to inhibit as well as to induce cytochrome P450s of the IA subfamily may be important in assessing the mutagenic and carcinogenic effects of MeIQ in mammals.     

The expression of c-myc related to the proliferation and transformation of rat liver-derived epithelial cells

The expression of c-myc protein was studied in primary cultures of rat hepatocytes and rat liver-derived epithelial cell lines. The levels of the protein were determined by flow cytometry using a monoclonal antibody to the c-myc protein. Freshly isolated hepatocytes from normal adult male Fischer F344 rats had low but detectable levels of the protein which were similar in the different ploidies. Higher levels were detected in immortalised but untransformed rat liver cell lines, and increased expression was observed during passage through the cell cycle. Following in vitro transformation of one of the immortalised epithelial cell lines by ras genes, similar levels of c-myc expression to those present in the untransformed cells was maintained. Transformation by activated aflatoxin B1 (AFB1) resulted in lower levels of expression. The cell cycle related level of expression was also seen in the transformed cells. Similar results to those observed in the in vitro ras transfected liver-derived cell lines were obtained from in vivo AFB1-induced rat hepatoma cell lines. These results demonstrate that continuously dividing rat liver-derived cell lines have higher levels of expression of c-myc protein than non-dividing, freshly isolated hepatocytes, and that there is no further elevation in the levels observed when these cell lines are transformed. In some cases decreased levels can result from malignant transformation.     

Development of a human cell line by selection and drug-metabolizing gene transfection with increased capacity to activate promutagens

We have isolated a human lymphoblastoid cell line with higher levels of native cytochrome P450IA1 activity and by DNA transfection introduced human cDNAs for a putative cytochrome P450IIA2 and epoxide hydrolase (E.C. 3.3.2.3). The resultant cell line, designated MCL-1, was substantially more sensitive to the mutagenicity of dimethylnitrosamine and benzo[a]pyrene than the AHH-1 cell line and was found to have increased metabolism of benzo[a]pyrene to dihydrodiols. The increase in native cytochrome P450IA1 activity was achieved by mutation and selection based on resistance to the phototoxicity of benzo[ghi]perylene. One resistant clone, designated L3, was used for subsequent studies. Two complete cDNAs, one encoding a putative cytochrome P450IIA2 and the other a microsomal epoxide hydrolase, were isolated from a human liver cDNA library. After introduction of the cDNAs into an expression vector and transfection into AHH-1 cells, gene expression was detected at the level of enzyme activity (epoxide hydrolase) or by increased sensitivity to dimethylnitrosamine cytotoxicity/mutagenicity (putative P450IIA2). A vector containing both cDNAs was then constructed and transfected into L3 cells to produce MCL-1 cells. The potential usefulness of drug-metabolizing gene transfection and of the MCL-1 cell line, in particular, for genetic toxicity testing is discussed.     

Characterization of a zinc-finger protein and its association with apoptosis in prostate cancer cells

BACKGROUND: The transition from androgen-dependent to androgen-independent prostate cancer is not fully understood but appears to involve multiple genetic changes. We have identified a gene, GC79, that is more highly expressed in androgen-dependent LNCaP-FGC human prostate cancer cells than in androgen-independent LNCaP-LNO human prostate cancer cells. Physiologic levels (0.1 nM:) of androgens repress expression of GC79 messenger RNA (mRNA) in LNCaP-FGC cells. To determine the role of GC79, we cloned its complementary DNA (cDNA) and functionally characterized its product. METHODS: The differentially expressed GC79 gene was cloned from human prostate cDNA libraries, sequenced, and transfected into mammalian cells to study its function. Expression of GC79 was analyzed in various adult and fetal human tissues and in prostate glands of castrated rats. The association of GC79 expression and apoptosis was investigated in COS-1 and LNCaP cells transfected with GC79 cDNA. All statistical tests are two-sided. RESULTS: Sequence analysis indicates that GC79 encodes a large, complex, multitype zinc-finger protein, containing nine C(2)H(2)-type zinc-finger domains, a cysteine-rich region, and a GATA C(4)-type zinc-finger domain. Castration-induced androgen withdrawal increased the expression of GC79 mRNA in the regressing rat ventral prostate, suggesting that the expression of GC79 mRNA is associated with the process of apoptotic cell death in the rat ventral prostate. Transfection and induction of GC79 cDNA in both COS-1 and LNCaP prostate cancer cells led to an apoptotic index that was eightfold higher (P:<.001, two-sided Student's t test) than that observed in uninduced transfected cells. CONCLUSIONS: We have cloned an androgen-repressible gene, GC79, that is potentially involved in apoptosis. This finding may have implications for the development of androgen-independent prostate cancer and, ultimately, for the treatment of prostate cancer.