Gene therapy specific for lung cancer using cell-type specific promoter

(1)CEA肺癌特异性基因治疗通过瘤内注射重组腺病毒载体（Ad.）在CEA启动子下表达HSV-tk基因，可以想象，CPA启动子的低活性导致HSV-tk基因在癌细胞中的表达不足以及不显著的抗肿瘤作用。我们将Cre/loxP系统应用于HSV-tk/GCV治疗CEA产生性肿瘤，构建了CEA启动子驱动的Cre重组酶CEA-Cre）和另一种设计用于Cre诱导表达HSV-tk基因的Ad与单独的Ad.CEA-TK感染相比，这些Ad的共感染使得人CEA产生癌细胞系对GCV的敏感性高8.4倍。 ...更多信息 肿瘤内注射Ad.CEA-Cre与Ad.CAG-loxP-TK的组合，随后进行GCV处理，完全根除了7只无胸腺小鼠中6只皮下组织中建立的CEA产生性肿瘤，而单独注射Ad.CEA-TK与GCV给药最多延缓接种肿瘤的生长。loxP系统应用于传统的细胞类型特异性基因治疗癌症，我们现在正在评估该系统在小鼠癌性腹膜炎模型中的疗效和副作用，以模拟未来临床应用于人类肺癌的胸膜炎。(2)Myc过表达小细胞肺癌（Myc-SCLC）的基因治疗含有与Myc结合基序连接的HSV-tk基因（Ad.Myc-TK）显示HSV-tk基因在Myc-SCLC细胞系中的细胞类型特异性表达。我们分析了腹腔注射Ad.Myc-TK后GCV处理对Myc-将SCLC接种于无胸腺小鼠的腹腔内。这种治疗成功地将肿瘤重量减少到未治疗小鼠的十四分之一，并完全根除。8只小鼠中有2只出现肿瘤。少

(1) Gene therapy specific for CEA-producing lung cancerRejection of CEA-producing tumors was not observed by intra-tumoral injection with a recombinant adenoviral vector (Ad.) expressing the HSV-tk gene under the CEA promoter (Ad.CEA-TK) followed by ganciclovir (GCV) treatment in vivo.It is conceivable that the low activity of the CPA promoter results in insufficient expression of the HSV-tk gene in cancer cells as well as in insignificant antitumor effects.To obtain enhanced expression of the HSV-tk gene exclusively in tumor cells and subsequent significant in vivo antitumor effects, we applied the Cre/loxP system to HSV-tk/GCV therapy for CEA-producing cancer.We constructed an Ad producing Cre recombinase driven by the CEA promoter (Ad.CEA-Cre) and another Ad designed for inducible expression of the HSV-tk gene by Cre (Ad.CAG-loxP-TK).Co-infection by these Ads rendered a human CEA-producing cancer cell line 8.4-fold more sensitive to GCV compared with infection by Ad.CEA-TK alone.On … More the other hand, co-infection with these Ads did not significantly change GCV sensitivity of CEA-non-producing cells.Intra-tumoral injection of Ad.CEA-Cre combined with Ad.CAG-loxP-TK followed by GCV treatment completely eradicated CEA-producing tumors established in the subcutis of 6 out of 7 athymic mice, whereas injection of Ad.CEA-TK alone with GCV administration at most retarded the growth of inoculated tumors.These results suggest distinct advantages of the Cre/loxP system applied in the conventional cell type-specific gene therapy against cancer.We are now evaluating the efficacy and side effects of this system in the peritonitis carcinomatosa model in mice, mimicking pleuritis for lung cancer in future clinical applications to human beings.(2) Gene therapy specific for Myc-overexpressing small cell lung cancer (Myc-SCLC)We previousely reported that an Ad. containing the HSV-tk gene ligated with the Myc-binding motif (Ad.Myc-TK) showed a cell-type specific expression of the HSV-tk gene in Myc-SCLC cell lines.We analyzed the efficacy of the intraperitoneal injection of Ad.Myc-TK followed by GCV treatment on Myc-SCLC inoculated in the peritoneal cavity of athymic mice.This treatment successfully reduced the weight of tumors to one fourteenth of that of untreated mice and completely eradicated tumors in 2 of 8 mice. Less