Inhibition of CD95-Mediated Apoptosis through β1 Integrin in the HSG Epithelial Cell Line

• Published in: Cell communication & adhesion 2006-01, Vol.13 (4), p.223-232
• Main Authors: Dang, Howard, Dehghan, Parastou Lizeth, Goodwiler, Kai, Chen, Shuo, Zardeneta, Gustavo, Zhang, Bin-Xian, Yeh, Chih-Ko
• Format: Article
• Language: English
• Subjects: apoptosis; Bcl-2; CD95; integrins; salivary gland
• ISSN: 1541-9061; 1543-5180
• DOI: 10.1080/15419060600848532

The HSG cell line serves as a model for salivary gland epithelial progenitor cell differentiation. In order for a progenitor cell to differentiate, the cell must maintain viability within its niche. Studies were designed to elucidate the mechanism for integrin-mediated HSG cell survival. HSG cells, grown on Matrigel®, were resistant to CD95-mediated apoptosis. Western blot analysis showed that Matrigel® induced the expression of bcl-2, bcl-xL, p63, and ΔNp63. This induction occurred by as early as 2 hrs and remained for 24 hrs. CD95-mediated apoptosis resistance was dependent, however, upon the expression of the bcl-2 family. Furthermore, Matrigel® induced bcl-2 family expression was dependent on the transactivation of the EGF receptor pathway since PD98059 and AG1478 inhibited Matrigel® induced bcl-2 family expression and caused HSG cells to be sensitive to CD95-mediated apoptosis. Activation of the EGF receptor pathway, by itself, however, was not sufficient to inhibit apoptosis. Blocking antibody showed that bcl-2 family expression was mediated through β1 integrin. These studies show that salivary progenitor epithelial cell survival is integrin dependent and involves the transactivation of the EGF receptor pathway.