Scott-Ritchey Research Center, College of Veterinary Medicine, Auburn University, Auburn, AL, United States of America.
Department of Pathobiology, College of Veterinary Medicine, Auburn University, Auburn, AL, United States of America.
PLoS One. 2020 Nov 9;15(11):e0240807. doi: 10.1371/journal.pone.0240807. eCollection 2020.
Gene therapy is a promising treatment option for cancer. However, its utility may be limited due to expression in off-target cells. Cancer-specific promoters such as telomerase reverse transcriptase (TERT), survivin, and chemokine receptor 4 (CXCR4) have enhanced activity in a variety of human and murine cancers, however, little has been published regarding these promoters in dogs. Given the utility of canine cancer models, the activity of these promoters along with adenoviral E2F enhanced E1a promoter (EEE) was evaluated in a variety of canine tumors, both from the endogenous gene and from exogenously administered constructs. Endogenous expression levels were measured for cTERT, cSurvivin, and cCXCR4 and were low for all three, with some non-malignant and some tumor cell lines and tissues expressing the gene. Expression levels from exogenously supplied promoters were measured by both the number of cells expressing the construct and the intensity of expression in individual cells. Exogenously supplied promoters were active in more cells in all tumor lines than in normal cells, with the EEE promoter being most active, followed by cTERT. The intensity of expression varied more with cell type than with specific promoters. Ultimately, no single promoter was identified that would result in reliable expression, regardless of the tumor type. Thus, these findings imply that identification of a pan-cancer promoter may be difficult. In addition, this data raises the concern that endogenous expression analysis may not accurately predict exogenous promoter activity.
基因治疗是癌症的一种有前途的治疗选择。然而，由于其在非靶细胞中的表达，其效用可能受到限制。端粒酶逆转录酶（TERT）、存活素和趋化因子受体 4（CXCR4）等肿瘤特异性启动子在多种人和鼠类癌症中具有增强的活性，但关于这些启动子在犬中的活性却鲜有报道。鉴于犬类癌症模型的实用性，评估了这些启动子以及腺病毒 E2F 增强 E1a 启动子（EEE）在多种犬类肿瘤中的活性，包括内源性基因和外源性给予的构建体。测量了 cTERT、cSurvivin 和 cCXCR4 的内源性表达水平，所有这三种基因的表达水平都较低，一些非恶性和一些肿瘤细胞系和组织表达了该基因。通过表达构建体的细胞数量和单个细胞中的表达强度来测量外源性提供的启动子的表达水平。与正常细胞相比，外源性提供的启动子在所有肿瘤系中的更多细胞中具有活性，其中 EEE 启动子最活跃，其次是 cTERT。表达强度与细胞类型的变化比与特定启动子的变化更大。最终，无论肿瘤类型如何，都没有确定一个能够产生可靠表达的单一启动子。因此，这些发现表明识别泛癌启动子可能很困难。此外，这些数据引起了人们的关注，即内源性表达分析可能无法准确预测外源性启动子的活性。
