Induction of Apoptosis to Rat Thyroid Follicular Epithelial Cell Line, FRTL-5 Cell

本研究用悬浮培养代替传统的单层培养，成功地诱导了FRTL-5细胞的TSH依赖性凋亡。鉴于悬浮培养中细胞与细胞或细胞与基质的黏附明显减弱，对FRTL-5细胞表达的黏附分子E-钙粘附素、整合素及其配体层粘连蛋白、4型胶原、纤维连接蛋白进行了免疫细胞化学检测。根据以上观察结果，推测TSH诱导FRTL-5细胞凋亡的可能性是由于这些细胞中黏附分子表达下调导致细胞黏附能力降低所致。有待回答的问题如下：1.TSH在单层培养细胞中抵抗凋亡的黏附分子的表达中起什么作用？2.如果有的话，有没有？在不含TSH的单层培养条件下，通过保持细胞黏附稳定而使FRTL-5细胞抵抗凋亡的调节因子？3.TSH是如何影响FRTL-5细胞黏附的，为什么去TSH会导致细胞黏附松动，最终导致细胞凋亡？

In the present study TSH dependnt apoptosis was successfully induced to FRTL-5 cells by replacing conventional monolayr culture with suspension culture.Since cell to cell or cell to matrix adhesion was considered to be significantly weakenend in suspension culture, the adhesion molecules such as E-cadherin, integrins and their ligands such as laminin, type 4 collagen, fibronectin which are expressed in FRTL-5 cells were immunocytochemically examined, and their expression in the cells was suggested to be up-regulated by TSH in suspension culture.The possibility was deduced from above observations that induction of TSH dependent apoptosis in FRTL-5 cells was initiated by the decreased adhesiveness of cells caused by down regulated expression of adhesion molecules in these cells.The questions remained to be answered are as follows : 1. What is the role of TSH in the expression of adhesion molecules in monolayr cultured cells which are resistant against apoptosis? 2. Are there, if any, regulatory factors which make FRTL-5 cells resistant vs apoptosis by keeping cell adhesion stable in the condition of monolayr culture without TSH? 3. How TSH exerts its effects on the cell adhesion in FRTL-5 cells, and why the deprivation of TSH results in the loosening of cell adhesion and finally in apotosis?