Topp W, Hall J D, Marsden M, Teresky A K, Rifkin D, Levine A J, Pollack R
Cancer Res. 1976 Nov;36(11 Pt. 2):4217-23.
Mouse teratocarcinoma cells from embryoid bodies were cultured in vitro to permit their differentiation into a number of cell types. Two enzyme activities, creatine phosphokinase (CPK) and the protease plasminogen activator, were studied to follow the developmental sequence of events in these embryoid body-derived cell cultures. CPK activity increased with time in culture, indicating the appearance of new cell types with brain- or muscle-specific enzyme activities. Plasminogen activator was detectable in extracts of embryoid bodies. This protease activity first increased and then decreased to a low level as the embryoid bodies in culture developed into differentiated cell types. These cell cultures also showed a decreased potential for tumor formation in syngeneic mice as a function of time in culture. This decrease in tumorigenic potential was correlated with the appearance of differentiated cells in vitro. Simian virus 40 (SV40) was used to infect and transform cells derived from embryoid bodies in culture. This was done to permit the establishment of cloned teratocarcinoma-derived cell lines. Twenty-nine distinct cloned permanent cell lines (called SVTER) containing the SV40-specific tumor antigen were obtained. None of these cell lines was capable of producing tumors in syngeneic mice. An analysis of the levels of creatine phosphokinase and plasminogen activator in these SVTER cell lines indicated that : (a) some cell lines had high CPK activity and little or no plasminogen activator activity, (b) some cell lines contained high levels of plasminogen activator activity with little or no CPK activity, and (c) some cell lines contained neither of these enzyme activities. No example of a cell line with high levels of both enzyme activities was observed, indicating that these two enzymes may participate in mutually exclusive developmental pathways. The SVTER cell lines may therefore be useful in reconstructing these developmental pathways in vitro.
将来自胚状体的小鼠畸胎瘤细胞进行体外培养，使其分化为多种细胞类型。研究了两种酶活性，即肌酸磷酸激酶（CPK）和蛋白酶纤溶酶原激活剂，以追踪这些胚状体衍生细胞培养物中事件的发育顺序。CPK活性随培养时间增加，表明出现了具有脑或肌肉特异性酶活性的新细胞类型。在胚状体提取物中可检测到纤溶酶原激活剂。随着培养中的胚状体发育成分化细胞类型，这种蛋白酶活性先增加后降至低水平。这些细胞培养物在同基因小鼠中形成肿瘤的潜力也随培养时间而降低。致瘤潜力的这种降低与体外分化细胞的出现相关。猿猴病毒40（SV40）用于感染和转化培养中来自胚状体的细胞。这样做是为了建立克隆的畸胎瘤衍生细胞系。获得了29个不同的含有SV40特异性肿瘤抗原的克隆永久细胞系（称为SVTER）。这些细胞系中没有一个能够在同基因小鼠中产生肿瘤。对这些SVTER细胞系中肌酸磷酸激酶和纤溶酶原激活剂水平的分析表明：（a）一些细胞系具有高CPK活性且纤溶酶原激活剂活性很少或没有，（b）一些细胞系含有高水平的纤溶酶原激活剂活性而CPK活性很少或没有，并且（c）一些细胞系这两种酶活性都没有。未观察到具有两种酶活性都高的细胞系实例，表明这两种酶可能参与相互排斥的发育途径。因此，SVTER细胞系可能有助于在体外重建这些发育途径。
