Poirier F, Jullien P, Dezelee P, Dambrine G, Esnault E, Benatre A, Calothy G
J Virol. 1984 Feb;49(2):325-32. doi: 10.1128/JVI.49.2.325-332.1984.
Expression of the src gene of Rous sarcoma virus in chicken embryo neuroretinal cells results in morphological transformation and sustained proliferation of this normally resting cell population. PA101 and PA104 are two mutants of Rous sarcoma virus which induce neuroretinal cell proliferation in the absence of morphological transformation. Their mitogenic property is temperature sensitive, and they both encode p60src proteins with low kinase activity. To study the role of the mitogenic function and protein kinase activity of p60src in tumorigenesis, we investigated the oncogenicity of PA101 and PA104. Both mutants were less tumorigenic than wild-type virus when injected into chicks. Tumorigenicity was further assayed by inoculating infected chicken embryo fibroblasts and neuroretinal cells onto the chorioallantoid membrane of embryonated duck eggs. This system provides a nonpermissive and immunodeficient environment for xenogenic cell grafting and allows the study of cell tumorigenicity within a temperature range of 37 to 39.5 degrees C. Chicken embryo fibroblasts and neuroretinal cells infected with PA101 were as tumorigenic as wild type-infected cells at 37 degrees C, but tumor development was significantly reduced at 39.5 degrees C. In contrast, both cell types infected with PA104 displayed sharply reduced tumorigenicity. Cell cultures derived from PA101 tumors induced on the chorioallantoid membrane were similar to the corresponding cells maintained in vitro in terms of morphology, production of plasminogen activator, relative amounts of phosphotyrosine in total cellular proteins, and phosphorylation of 34,000-molecular-weight protein. These results indicate that the expression of the mitogenic function of src does not account per se for cell tumorigenicity and that tumor formation is compatible with low levels of p60src protein kinase activity.
劳氏肉瘤病毒的src基因在鸡胚神经视网膜细胞中的表达会导致这种正常静止的细胞群体发生形态转化和持续增殖。PA101和PA104是劳氏肉瘤病毒的两个突变体，它们在不发生形态转化的情况下诱导神经视网膜细胞增殖。它们的促有丝分裂特性对温度敏感，并且都编码具有低激酶活性的p60src蛋白。为了研究p60src的促有丝分裂功能和蛋白激酶活性在肿瘤发生中的作用，我们研究了PA101和PA104的致癌性。当将这两种突变体注射到雏鸡体内时，它们的致癌性均低于野生型病毒。通过将感染的鸡胚成纤维细胞和神经视网膜细胞接种到孵化鸭胚的尿囊绒膜上来进一步检测致癌性。该系统为异种细胞移植提供了一个非允许且免疫缺陷的环境，并允许在37至39.5摄氏度的温度范围内研究细胞致癌性。在37摄氏度时，感染PA101的鸡胚成纤维细胞和神经视网膜细胞与感染野生型的细胞一样具有致癌性，但在39.5摄氏度时肿瘤发展明显减少。相比之下，感染PA104的两种细胞类型的致癌性均急剧降低。从尿囊绒膜上诱导的PA101肿瘤获得的细胞培养物在形态、纤溶酶原激活物的产生、总细胞蛋白中磷酸酪氨酸的相对含量以及34000分子量蛋白的磷酸化方面与体外培养的相应细胞相似。这些结果表明，src促有丝分裂功能的表达本身并不能解释细胞的致癌性，并且肿瘤形成与低水平的p60src蛋白激酶活性是相容的。
