目的 构建前列腺特异性膜抗原启动子增强子靶向性调控的 U PRT基因真核表达重组质粒 (p PS-MAenhancer/ promoter- U PRT)。方法 采用 PCR技术从大肠杆菌 JM10 9基因组中扩增 U PRT基因 ,通过分子克隆技术将其克隆到包括前列腺特异性...目的 构建前列腺特异性膜抗原启动子增强子靶向性调控的 U PRT基因真核表达重组质粒 (p PS-MAenhancer/ promoter- U PRT)。方法 采用 PCR技术从大肠杆菌 JM10 9基因组中扩增 U PRT基因 ,通过分子克隆技术将其克隆到包括前列腺特异性膜抗原启动子增强子靶向性调控的 p EGFP- 1的质粒。利用重组质粒 p PS-MAenhancer/ promoter- U PRT)转染 L Ncap细胞 ,MTT法检测 5 -氯尿嘧啶 (5 - FU)对转染 L Ncap细胞存活率的影响。结果 质粒 p PSMAenhancer/ promoter- EGFP双酶切去除 EGFP,连接上 U PRT基因 ,成功构建 p PSMAenhancer/ promoter- UPRT,并转染 L Ncap细胞 ,使 L Ncap细胞对 5 - FU的杀伤敏感性大大提高。结论 p PSMAenhancer/ promoter- U PRT的构建和表达 ,为进一步研究 UPRT基因对 5 - FU的靶向性杀伤前列腺癌细胞增强作用和对前列腺癌自杀基因系统 (CD/ 5 -FC系统 )的放大效应奠定了基础。展开更多
Background Cytosine deaminase （CD） converts 5-fluorocytosine （5-FC） to 5-fluorouracil （5-FU） in CD/5-FC gene therapy, 5-FU will be mostly converted into nontoxic 13-alanine without uracil phosphoribosyltransfera...Background Cytosine deaminase （CD） converts 5-fluorocytosine （5-FC） to 5-fluorouracil （5-FU） in CD/5-FC gene therapy, 5-FU will be mostly converted into nontoxic 13-alanine without uracil phosphoribosyltransferase （UPRT）. UPRT catalyzes the conversion of 5-FU to 5-fluorouridine monophosphate, which directly kills CD：：UPRT-expressing cells and surrounding cells via the bystander effect. But the pharmacokinetics and the bystander effect of CD：：UPRT/5-FC has not been verified in vivo and in vitro. Before the CD：：UPRT/5-FC bi-gene therapy system is used in clinical trial, it is essential to monitor the transgene expression and function in vivo. Thus, we developed a preclinical tumor model to investigate the feasibility of using ^19F-magnetic resonance spectroscopy （^19F-MRS） and optical imaging to measure non-invasive CD and UPRT expression and its bystander effect. Methods C6 and C6-CD：：UPRT cells were cultured with 5-FC. The medium, cells and their mixture were analyzed by ^19F-MRS. Rats with intracranial xenografted encephalic C6-CD：：UPRT glioma were injected intraperitoneally with 5-FC and their ^19F-MRS spectra recorded. Then the pharmacokinetics of 5-FC was proved. Mixtures of C6 and C6-CD：：UPRT cells at different ratios were cultured with 5-FC and the cytotoxic efficacy and survival rate of cells recorded. To determine the mechanism of the bystander effect, the culture media from cell comprising 25% and 75% C6-CD：：UPRT cells were examined by ^19F-MRS. A comparative study of mean was performed using analysis of variance （ANOVA）. Results ^19F-MRS on samples from C6-CD：：UPRT cells cultured with 5-FC showed three broad resonance signals corresponding to 5-FC, 5-FU and fluorinated nucleotides （F-Nuctd）. For the C6 mixture, only the 5-FC peak was detected. In vivo serial ^19F-MRS spectra showed a strong 5-FC peak and a weak 5-FU peak at 20 minutes after 5-FC injection. The 5-FU concentration reached a maximum at about 50 minutes. The F-Nuctd signal appeared after about 1 hour, reached a maximum at around 160 minutes, and was detectable for several hours. At a 10% ratio of C6-CD：：UPRT cells, the survival rate was （79.55±0.88）% （P 〈0.01）. As the C6-CD：：UPRT ratio increased, the survival rate of the cells decreased. ^19F-MRS showed that the signals for 5-FU and F-Nuctd in the culture medium increased as the ratio of C6-CD：：UPRT in the mixture increased. Conclusions ^19F-MRS studies indicated that C6-CD：：UPRT cells could effectively express CD and UPRT enzymes. The CD：：UPRT/5-FC system showed an obvious bystander effect. This study demonstrated that CD：：UPRT/5-FC gene therapy is suitable for 5-FC to F-Nuctd metabolism; and ^19F-MRS can monitor transferred CD：：UPRT gene expression and catalysis of substrates noninvasively, dynamically and quantitatively.展开更多
文摘目的 构建前列腺特异性膜抗原启动子增强子靶向性调控的 U PRT基因真核表达重组质粒 (p PS-MAenhancer/ promoter- U PRT)。方法 采用 PCR技术从大肠杆菌 JM10 9基因组中扩增 U PRT基因 ,通过分子克隆技术将其克隆到包括前列腺特异性膜抗原启动子增强子靶向性调控的 p EGFP- 1的质粒。利用重组质粒 p PS-MAenhancer/ promoter- U PRT)转染 L Ncap细胞 ,MTT法检测 5 -氯尿嘧啶 (5 - FU)对转染 L Ncap细胞存活率的影响。结果 质粒 p PSMAenhancer/ promoter- EGFP双酶切去除 EGFP,连接上 U PRT基因 ,成功构建 p PSMAenhancer/ promoter- UPRT,并转染 L Ncap细胞 ,使 L Ncap细胞对 5 - FU的杀伤敏感性大大提高。结论 p PSMAenhancer/ promoter- U PRT的构建和表达 ,为进一步研究 UPRT基因对 5 - FU的靶向性杀伤前列腺癌细胞增强作用和对前列腺癌自杀基因系统 (CD/ 5 -FC系统 )的放大效应奠定了基础。
基金This study was supported by grants from Jiangsu Provincial Health Department （No. RC2002075） and Natural Science Foundation of Jiangsu Province （No. BK2007257）.
文摘Background Cytosine deaminase （CD） converts 5-fluorocytosine （5-FC） to 5-fluorouracil （5-FU） in CD/5-FC gene therapy, 5-FU will be mostly converted into nontoxic 13-alanine without uracil phosphoribosyltransferase （UPRT）. UPRT catalyzes the conversion of 5-FU to 5-fluorouridine monophosphate, which directly kills CD：：UPRT-expressing cells and surrounding cells via the bystander effect. But the pharmacokinetics and the bystander effect of CD：：UPRT/5-FC has not been verified in vivo and in vitro. Before the CD：：UPRT/5-FC bi-gene therapy system is used in clinical trial, it is essential to monitor the transgene expression and function in vivo. Thus, we developed a preclinical tumor model to investigate the feasibility of using ^19F-magnetic resonance spectroscopy （^19F-MRS） and optical imaging to measure non-invasive CD and UPRT expression and its bystander effect. Methods C6 and C6-CD：：UPRT cells were cultured with 5-FC. The medium, cells and their mixture were analyzed by ^19F-MRS. Rats with intracranial xenografted encephalic C6-CD：：UPRT glioma were injected intraperitoneally with 5-FC and their ^19F-MRS spectra recorded. Then the pharmacokinetics of 5-FC was proved. Mixtures of C6 and C6-CD：：UPRT cells at different ratios were cultured with 5-FC and the cytotoxic efficacy and survival rate of cells recorded. To determine the mechanism of the bystander effect, the culture media from cell comprising 25% and 75% C6-CD：：UPRT cells were examined by ^19F-MRS. A comparative study of mean was performed using analysis of variance （ANOVA）. Results ^19F-MRS on samples from C6-CD：：UPRT cells cultured with 5-FC showed three broad resonance signals corresponding to 5-FC, 5-FU and fluorinated nucleotides （F-Nuctd）. For the C6 mixture, only the 5-FC peak was detected. In vivo serial ^19F-MRS spectra showed a strong 5-FC peak and a weak 5-FU peak at 20 minutes after 5-FC injection. The 5-FU concentration reached a maximum at about 50 minutes. The F-Nuctd signal appeared after about 1 hour, reached a maximum at around 160 minutes, and was detectable for several hours. At a 10% ratio of C6-CD：：UPRT cells, the survival rate was （79.55±0.88）% （P 〈0.01）. As the C6-CD：：UPRT ratio increased, the survival rate of the cells decreased. ^19F-MRS showed that the signals for 5-FU and F-Nuctd in the culture medium increased as the ratio of C6-CD：：UPRT in the mixture increased. Conclusions ^19F-MRS studies indicated that C6-CD：：UPRT cells could effectively express CD and UPRT enzymes. The CD：：UPRT/5-FC system showed an obvious bystander effect. This study demonstrated that CD：：UPRT/5-FC gene therapy is suitable for 5-FC to F-Nuctd metabolism; and ^19F-MRS can monitor transferred CD：：UPRT gene expression and catalysis of substrates noninvasively, dynamically and quantitatively.
