Variants of integrin beta 4 subunit in human endometrial adenocarcinoma cells: mediators of ECM-induced differentiation?

The influence of extracellular matrix (ECM) on expression and function of integrins in carcinogenesis and differentiation is not well understood, but the importance of altered adhesion features for tumor development and progression is obvious. Integrins as versatile molecules are mainly responsible for mediating cell-matrix interactions and transmembrane signal transduction. They are capable of transducing outside-in signals from ECM components or conversely to organize the matrix by inside-out signaling. In the study presented here, we report that the reconstituted basement membrane, Matrigel, which induces morphological and functional differentiation of the endometrial adenocarcinoma cell line HEC 1B(L), also regulates the expression of various forms of the integrin beta 4 subunit. Furthermore, we were able to identify full-length isoforms with and without an altered cytoplasmic domain as well as truncated forms. Our findings suggest a regulatory role of integrin beta 4 isoforms and fragments in the process of in vitro differentiation of HEC 1B(L).