Vitale M, Di Matola T, Fenzi G, Illario M, Rossi G
Dipartimento di Biologia e Patologia Cellulare e Molecolare, Università Federico II, Naples, Italy.
J Clin Endocrinol Metab. 1998 Oct;83(10):3673-80. doi: 10.1210/jcem.83.10.5175.
Apoptosis or programmed cell death occurs in a wide variety of cell types when adhesion to extracellular matrix (ECM) is denied. Invasion and metastasis by tumor cells involve the loss of normal cell-ECM contacts and require independence from such control mechanisms. We studied whether the immortalized thyroid cell line TAD-2 is a model suitable to investigate thyroid cell-ECM interaction, and we analyzed the role of integrin-fibronectin (FN) interaction in apoptosis. Adhesion, spreading, and cytoskeleton organization in TAD-2 cultured cells were dependent upon integrin-FN interaction. Cell spreading and cytoskeletal organization were coupled to deposition of insoluble FN induced by serum. Expression of integrin-FN receptors was demonstrated by flow cytofluorometry with specific antibodies, and strong integrin-dependent adhesion was demonstrated by attachment assays to immobilized FN. Apoptosis, occurring in different culture conditions, was determined by cell morphology and DNA electrophoretic analysis and quantitated by flow cytometry in propidium iodide-stained cells. Thyroid cells underwent apoptosis in the presence of serum when adhesion was prevented by specific peptides that inhibit integrin binding to FN (RGD-containing peptides) or by coating the culture plates with agar. In serum-free cultures, apoptosis was prevented by insoluble FN immobilized on the plates, but not by soluble FN. These results suggest that the TAD-2 cell line is a good model to study thyroid cell-ECM interaction, that FN, assembled into insoluble matrix, is required for cytoskeletal organization and to prevent thyroid cell apoptosis, and that integrin-mediated adhesion is involved in this process.
当细胞与细胞外基质（ECM）的黏附被阻断时，细胞凋亡或程序性细胞死亡会在多种细胞类型中发生。肿瘤细胞的侵袭和转移涉及正常细胞与ECM接触的丧失，并且需要摆脱这种控制机制的影响。我们研究了永生化甲状腺细胞系TAD-2是否是一个适合研究甲状腺细胞与ECM相互作用的模型，并且分析了整合素-纤连蛋白（FN）相互作用在细胞凋亡中的作用。TAD-2培养细胞的黏附、铺展和细胞骨架组织依赖于整合素-FN相互作用。细胞铺展和细胞骨架组织与血清诱导的不溶性FN的沉积相关。通过使用特异性抗体的流式细胞荧光术证实了整合素-FN受体的表达，并且通过对固定化FN的附着试验证实了强烈的整合素依赖性黏附。在不同培养条件下发生的细胞凋亡通过细胞形态学和DNA电泳分析来确定，并通过对碘化丙啶染色细胞的流式细胞术进行定量。当通过抑制整合素与FN结合的特异性肽（含RGD的肽）或用琼脂包被培养板来阻止黏附时，甲状腺细胞在有血清存在的情况下会发生凋亡。在无血清培养中，固定在平板上的不溶性FN可防止细胞凋亡，但可溶性FN则不能。这些结果表明，TAD-2细胞系是研究甲状腺细胞与ECM相互作用的良好模型，组装成不溶性基质的FN是细胞骨架组织和防止甲状腺细胞凋亡所必需的，并且整合素介导的黏附参与了这一过程。
