Legrand C, Mousset S, Salomé N, Rommelaere J
Department of Molecular Biology, Université Libre de Bruxelles, Rhode-St-Genèse, Belgium.
J Gen Virol. 1992 Aug;73 ( Pt 8):2003-9. doi: 10.1099/0022-1317-73-8-2003.
The established line of normal Fisher rat fibroblasts (FR3T3) is naturally resistant to the parvovirus minute virus of mice (MVM), and was used as a model system to study the influence of stepwise transformation on the susceptibility of cells to this virus. When transformed with genes encoding the class I nuclear oncoproteins large T antigen of polyomavirus (PyLT) or v-myc, cells retained a normal appearance, but acquired some ability to form colonies in soft agar. On the other hand, the class II transforming oncogenes encoding the middle T antigen of polyomavirus (PyMT) and c-Ha-ras-1 induced both morphological alterations and a high capacity for anchorage-independent growth in transfected cells. The concomitant expression of oncogenes from both classes (PyLT-(+)PyMT; v-myc+c-Ha-ras-1) induced a supertransformed phenotype characterized by the piling-up of cells into poorly adherent foci, even in low density cultures. The progressive transformation of this cellular system was found to coincide with a gradual increase in its susceptibility to MVMp (MVM prototype strain) infection. Compared to parental cells, class I, class II and double transformants proved to be sensitized to killing by MVMp to a low, moderate and large extent, respectively. Thus, oncogenes from different functional classes appeared to cooperate in the responsiveness of cells to parvovirus attack. Interestingly, this cooperation exacerbated both the killing of infected cells and their capacity to produce viral non-structural (NS) proteins, in agreement with the reported cytotoxic activity of NS polypeptides. Therefore, in this system, parameters of the parvovirus life cycle may serve as indications of the overall progression of the transformation process.
已建立的正常Fisher大鼠成纤维细胞系（FR3T3）对小鼠细小病毒（MVM）天然具有抗性，被用作模型系统来研究逐步转化对细胞对该病毒易感性的影响。当用编码多瘤病毒（PyLT）或v-myc的I类核癌蛋白大T抗原的基因进行转化时，细胞保持正常外观，但获得了在软琼脂中形成集落的一些能力。另一方面，编码多瘤病毒（PyMT）和c-Ha-ras-1的中T抗原的II类转化癌基因在转染细胞中诱导了形态改变和高锚定非依赖性生长能力。两类癌基因的同时表达（PyLT-(+)PyMT；v-myc+c-Ha-ras-1）诱导了一种超转化表型，其特征是细胞堆积成粘附性差的集落，即使在低密度培养物中也是如此。发现该细胞系统的逐步转化与其对MVMp（MVM原型株）感染的易感性逐渐增加相吻合。与亲代细胞相比，I类、II类和双重转化体分别被证明对MVMp杀伤的敏感性低、中、高。因此，来自不同功能类别的癌基因似乎在细胞对细小病毒攻击的反应中协同作用。有趣的是，这种协同作用加剧了感染细胞的杀伤及其产生病毒非结构（NS）蛋白的能力，这与报道的NS多肽的细胞毒性活性一致。因此，在该系统中，细小病毒生命周期的参数可作为转化过程总体进展的指标。
