Imaizumi K, Hasegawa Y, Kawabe T, Emi N, Saito H, Naruse K, Shimokata K
First Department of Internal Medicine, Nagoya University School of Medicine, Japan.
Am J Respir Cell Mol Biol. 1998 Feb;18(2):205-12. doi: 10.1165/ajrcmb.18.2.2821.
Tumor cells expressing the herpes simplex virus-thymidine kinase (HSV-tk) gene become sensitive to ganciclovir (GCV), and the phenomenon by which tumor cells surrounding the HSV-tk expressing cells also become sensitive to GCV is known as the "bystander effect." The purpose of this study was to investigate the bystander effect in human lung-cancer cell lines, and the role of gap-junctional intercellular communication as the mechanism responsible for it. Gap-junctional intercellular communication was measured both with a dye-transfer assay involving single-cell microinjection of Lucifer Yellow and with a PKH26/calcein-AM double-dye-transfer assay. Significant bystander tumoricidal effect was observed in lung-cancer cell lines when cultured cells contained only 10% HSV-tk expressing cells. This was also observed to occur with cell lines of different origin or from different species. Although gap-junctional intercellular communication characterized by rapid transfer of Lucifer Yellow was not observed, we did detect gap-junctional communication marked by the slow transfer of calcein-AM in lung-cancer cell lines. However, neither an inhibitor (1-octanol) nor an enhancer (all trans-retinoic acid [ATRA]) of gap-junctional communication affected the extent of the bystander effect. These findings suggest that low levels of gap-junctional communication may be efficient for producing the bystander effect in lung-cancer cells, or that other mechanisms may underlie this effect. Although gap-junctional communication may play an important role in generating the bystander effect in tumor cells expressing the HSV-tk gene, further knowledge of the mechanism of this effect may help improve the treatment of lung cancer with an HSV-tk system.
表达单纯疱疹病毒胸苷激酶（HSV - tk）基因的肿瘤细胞对更昔洛韦（GCV）敏感，而围绕表达HSV - tk的细胞周围的肿瘤细胞也对GCV敏感的现象被称为“旁观者效应”。本研究的目的是调查人肺癌细胞系中的旁观者效应，以及缝隙连接细胞间通讯作为其产生机制所起的作用。缝隙连接细胞间通讯通过涉及单细胞微量注射荧光素黄的染料转移测定法和PKH26/钙黄绿素 - AM双染料转移测定法进行测量。当培养细胞中仅含有10%表达HSV - tk的细胞时，在肺癌细胞系中观察到显著的旁观者杀瘤效应。在不同来源或不同物种的细胞系中也观察到了这种现象。虽然未观察到以荧光素黄快速转移为特征的缝隙连接细胞间通讯，但我们在肺癌细胞系中确实检测到了以钙黄绿素 - AM缓慢转移为标志的缝隙连接通讯。然而，缝隙连接通讯的抑制剂（1 - 辛醇）或增强剂（全反式维甲酸[ATRA]）均未影响旁观者效应的程度。这些发现表明，低水平的缝隙连接通讯可能有效地在肺癌细胞中产生旁观者效应，或者其他机制可能是这种效应的基础。虽然缝隙连接通讯可能在表达HSV - tk基因的肿瘤细胞中产生旁观者效应方面发挥重要作用，但对这种效应机制的进一步了解可能有助于改善HSV - tk系统治疗肺癌的效果。
