Cancer cell specific cytotoxic gene expression mediated by ARF tumor suppressor promoter constructs
Cancer cell specific cytotoxic gene expression mediated by ARF tumor suppressor promoter constructs
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ARF肿瘤抑制启动子构建体介导的癌细胞特异性细胞毒性基因表达
DOI：
10.1016/j.bbrc.2014.05.102
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
Ohtani K
中科院分区：
文献类型：
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作者：
Kurayoshi K;Ozono E;Iwanaga R;Bradford AP;Komori H;Ohtani K
在目前的癌症治疗方案中，如放疗和化疗，对正常细胞的副作用是根治性治疗的主要障碍。为了避免这些副作用，需要一种针对癌细胞的方法。一种特异性靶向癌细胞的方法是利用癌症特异性启动子来表达细胞毒基因(自杀基因疗法)或病毒复制所需的病毒基因(溶瘤病毒疗法)。为此，所选择的启动子在正常细胞中应具有最低的活性以避免副作用，而在多种癌症中应具有高活性以获得最佳的治疗效果。与仅在有限的肿瘤谱中具有高活性的AFP、CEA和PSA启动子不同，E2F1启动子在多种癌症中表现出高活性。这是基于致癌机制的。Rb途径的缺陷和转录因子E2F的激活是Rb途径的主要靶点，几乎在所有的癌症中都能观察到。因此，主要受E2F调控的E2F1启动子在多种肿瘤中具有高活性。然而，在正常生长的细胞中，E2F也被生长刺激激活，这表明E2F1启动子在正常生长的细胞中也可能是高活性的。相反，我们发现肿瘤抑制因子ARF启动子被pRB强制失活诱导的E2F活性解除调节激活，但对生长刺激诱导的生理E2F活性没有反应。我们还发现，激活ARF启动子的非调控E2F活性只在癌细胞系中检测到。这些观察表明，ARF启动子仅在癌细胞中被E2F激活，因此可能比E2F1启动子更具癌细胞特异性，以驱动基因表达。我们在这里显示，与E2F1启动子相比，ARF启动子在正常生长的成纤维细胞中活性较低，并显示出更高的癌细胞特异性。我们还证明了在ARF启动子控制下表达HSV-TK的腺病毒在正常生长的成纤维细胞中显示出比E2F1启动子更低的细胞毒性，但在癌细胞系中具有同等的细胞毒性。这些结果表明，ARF启动子被解除调控的E2F活性特异性激活，是驱动治疗性细胞毒基因表达的极佳候选基因，尤其是在癌细胞中。
In current cancer treatment protocols, such as radiation and chemotherapy, side effects on normal cells are major obstacles to radical therapy. To avoid these side effects, a cancer cell-specific approach is needed. One way to specifically target cancer cells is to utilize a cancer specific promoter to express a cytotoxic gene (suicide gene therapy) or a viral gene required for viral replication (oncolytic virotherapy). For this purpose, the selected promoter should have minimal activity in normal cells to avoid side effects, and high activity in a wide variety of cancers to obtain optimal therapeutic efficacy.In contrast to the AFP, CEA and PSA promoters, which have high activity only in a limited spectrum of tumors, the E2F1 promoter exhibits high activity in wide variety of cancers. This is based on the mechanism of carcinogenesis. Defects in the RB pathway and activation of the transcription factor E2F, the main target of the RB pathway, are observed in almost all cancers. Consequently, the E2F1 promoter, which is mainly regulated by E2F, has high activity in wide variety of cancers. However, E2F is also activated by growth stimulation in normal growing cells, suggesting that the E2F1 promoter may also be highly active in normal growing cells. In contrast, we found that the tumor suppressor ARF promoter is activated by deregulated E2F activity, induced by forced inactivation of pRB, but does not respond to physiological E2F activity induced by growth stimulation. We also found that the deregulated E2F activity, which activates the ARF promoter, is detected only in cancer cell lines. These observations suggest that ARF promoter is activated by E2F only in cancer cells and therefore may be more cancer cell-specific than E2F1 promoter to drive gene expression.We show here that the ARF promoter has lower activity in normal growing fibroblasts and shows higher cancer cell-specificity compared to the E2F1 promoter. We also demonstrate that adenovirus expressingHSV-TKunder the control of the ARF promoter shows lower cytotoxicity than that of the E2F1 promoter, in normal growing fibroblasts but has equivalent cytotoxicity in cancer cell lines. These results suggest that the ARF promoter, which is specifically activated by deregulated E2F activity, is an excellent candidate to drive therapeutic cytotoxic gene expression, specifically in cancer cells.