Kawamura I, Morishita R, Tomita N, Lacey E, Aketa M, Tsujimoto S, Manda T, Tomoi M, Kida I, Higaki J, Kaneda Y, Shimomura K, Ogihara T
Pharmacological Research Laboratories, Fujisawa Pharmaceutical Company, Yodogawaku, Japan.
Gene Ther. 1999 Jan;6(1):91-7. doi: 10.1038/sj.gt.3300819.
Cancer cachexia, characterized by anorexia, weight loss and progressive tissue wasting, has been postulated to be mediated by various cytokines. However, the precise mechanism of cachexia induction is not fully explained. We have developed synthetic double-stranded oligodeoxynucleotides (ODN) as 'decoy' cis-elements that block the binding of nuclear factors to promoter regions of targeted genes, resulting in the inhibition of gene transactivation in vivo as well as in vitro. This novel molecular strategy could be useful for treating a broad range of human diseases including cancer. In this study, we injected decoy ODN targeting the transcriptional factor, NF-kappa B (NF kappa B) binding cis-elements, which are essential for transactivation of gene expression of cytokines, directly into tumors of adenocarcinoma colon26 in mice, in order to examine whether or not cachexia is alleviated by inhibiting the action of cytokines. Tumor growth was not affected by transfection of NF kappa B decoy ODN as compared with scrambled decoy ODN. Nevertheless, transfection of NF kappa B decoy, but not scrambled decoy, ODN resulted in attenuation of the reductions in body weight, epididymal fat, gastrocnemius muscle mass and food intake, which were induced by the tumor presence. Interleukin 6 mRNA in the tumor was also markedly decreased by the transfection of NF kappa B decoy ODN. It is known that the transcriptional factor E2F plays a pivotal role in the coordinated transactivation of cell cycle regulatory genes. Therefore, we hypothesized that the introduction of synthetic double-stranded DNA with high affinity for E2F in vivo as 'decoy' cis-elements might inhibit the tumor growth of colon26, resulting in turn in inhibition of cachexia induction. However, injection of E2F decoy ODN failed to inhibit tumor growth and cachexia induction, as compared with mismatched decoy ODN. Overall, the present study demonstrated that cachexia induced by adenocarcinoma colon26 was inhibited by blocking of NF kappa B, using a novel molecular decoy strategy, without an effect on tumor growth, and also that tumor growth and cachexia induction in the colon26 model were not affected by E2F decoy ODN. These results suggest that cytokines regulated by NF kappa B may play a pivotal role in the induction of cachexia by colon26, providing a new therapeutic strategy for cancer cachexia.
癌症恶病质的特征为厌食、体重减轻和进行性组织消耗，据推测是由多种细胞因子介导的。然而，恶病质诱导的确切机制尚未完全阐明。我们已开发出合成双链寡脱氧核苷酸（ODN）作为“诱饵”顺式元件，其可阻断核因子与靶基因启动子区域的结合，从而在体内和体外抑制基因反式激活。这种新型分子策略可能对治疗包括癌症在内的多种人类疾病有用。在本研究中，我们将靶向转录因子NF-κB（核因子κB）结合顺式元件的诱饵ODN直接注射到小鼠结肠腺癌26的肿瘤中，该顺式元件对于细胞因子基因表达的反式激活至关重要，目的是检查通过抑制细胞因子的作用是否能减轻恶病质。与乱序诱饵ODN相比，NF-κB诱饵ODN的转染对肿瘤生长没有影响。然而，NF-κB诱饵ODN而非乱序诱饵ODN的转染导致由肿瘤存在所诱导的体重、附睾脂肪、腓肠肌质量和食物摄入量的降低有所减轻。NF-κB诱饵ODN的转染还使肿瘤中的白细胞介素6 mRNA显著减少。已知转录因子E2F在细胞周期调节基因的协同反式激活中起关键作用。因此，我们推测在体内引入对E2F具有高亲和力的合成双链DNA作为“诱饵”顺式元件可能会抑制结肠26的肿瘤生长，进而抑制恶病质的诱导。然而，与错配诱饵ODN相比，注射E2F诱饵ODN未能抑制肿瘤生长和恶病质诱导。总体而言，本研究表明，采用新型分子诱饵策略阻断NF-κB可抑制结肠腺癌26诱导的恶病质，且对肿瘤生长无影响，同时还表明结肠26模型中的肿瘤生长和恶病质诱导不受E2F诱饵ODN的影响。这些结果表明，由NF-κB调节的细胞因子可能在结肠26诱导恶病质过程中起关键作用，为癌症恶病质提供了一种新的治疗策略。
