Katsantonis J, Tosca A, Koukouritaki S B, Theodoropoulos P A, Gravanis A, Stournaras C
Department of Dermatology, School of Medicine, University of Crete, Heraklion, Greece.
Cell Biochem Funct. 1994 Dec;12(4):267-74. doi: 10.1002/cbf.290120407.
The state of polymerization of actin and the organization of actin filaments is widely believed to be related to cellular transformation. Since the intracellular monomer (G) and filamentous (F) actin content reflects the state of microfilament polymerization, we measured the G/total actin ratio in primary cultures of normal and malignant human keratinocytes. In normal keratinocytes the mean value of this ratio was 0.30 +/- 0.03 (mean +/- SE, n = 15), while in basal cell carcinoma (BCC) keratinocytes it was 0.49 +/- 0.03 (n = 8) and in squamous cell carcinoma keratinocytes (SCC) 0.5 +/- 0.07 (n = 4), indicating a 1.7-fold increase of the G/total actin ratio in malignant cells. These results imply that the proportion of polymerized actin is decreased markedly in malignant keratinocytes, suggesting alterations of microfilament structures which probably occur during the transformation process. This was supported by the morphological changes of microfilament structures as assessed by fluorescence microscopy. A different distribution of actin filaments in normal and malignant cells became evident; stress-fibres were converging in patches at several points in SCC cells, when compared to normal keratinocytes. Furthermore, incubation of normal and malignant keratinocytes with cytochalasin B indicated differences in the resistance of their microfilament networks. After 1 h exposure to 10(-6) and 10(-5) M cytochalasin B, microfilaments in normal cells appeared to be less affected than their counterparts in neoplastic cells. Even in a high excess of cytochalasin B (10(-4) M), normal keratinocytes preserved their shape, while both basal cell and SCC were totally disrupted.(ABSTRACT TRUNCATED AT 250 WORDS)
肌动蛋白的聚合状态和肌动蛋白丝的组织被广泛认为与细胞转化有关。由于细胞内单体（G）和丝状（F）肌动蛋白含量反映了微丝聚合状态，我们测量了正常和恶性人角质形成细胞原代培养物中的G/总肌动蛋白比率。在正常角质形成细胞中，该比率的平均值为0.30±0.03（平均值±标准误，n = 15），而在基底细胞癌（BCC）角质形成细胞中为0.49±0.03（n = 8），在鳞状细胞癌角质形成细胞（SCC）中为0.5±0.07（n = 4），表明恶性细胞中G/总肌动蛋白比率增加了1.7倍。这些结果意味着恶性角质形成细胞中聚合肌动蛋白的比例明显降低，提示微丝结构的改变可能发生在转化过程中。荧光显微镜评估的微丝结构形态变化支持了这一点。正常细胞和恶性细胞中肌动蛋白丝的分布明显不同；与正常角质形成细胞相比，SCC细胞中的应力纤维在几个点上聚集形成斑块。此外，用细胞松弛素B孵育正常和恶性角质形成细胞表明它们的微丝网络抗性存在差异。暴露于10^(-6)和10^(-5) M细胞松弛素B 1小时后，正常细胞中的微丝似乎比肿瘤细胞中的微丝受影响更小。即使在高浓度的细胞松弛素B（10^(-4) M）下，正常角质形成细胞仍能保持其形状，而基底细胞和SCC细胞则完全被破坏。（摘要截短于250字）
