Dynamic analysis of hepatoma spheroid formation: roles of E-cadherin and beta1-integrin.
A spheroid is an in vitro multicellular aggregate that provides a microenvironment resembling that of normal tissue in vivo. Although cell adhesion molecules such as integrins and cadherins have been implicated in participating in the process of spheroid formation, little is known about the timing of their action. In this study, we have employed an image-based quantitative method to investigate the compactness of cell aggregates during hepatoma spheroid formation in a dynamic fashion. By modulating beta1-integrin and E-cadherin activity with specific blocking antibodies, ion chelators, and RGD-sequence-containing peptides, we show that these cell adhesion molecules mediate the formation of spheroids through the establishment of complex cell-cell and cell-extracellular matrix (ECM) interactions. The dynamics of spheroid formation can be separated into three stages. In the first stage, ECM fibers act as a long-chain linker for the attachment of dispersed single-cells to form loose aggregations through the binding of integrins. This is followed by a delay period in which cell aggregates pause in compaction, presumably because of the accumulation of sufficient amounts of E-cadherins. In the third stage, strong homophilic interaction of E-cadherins is a major factor for the morphological transition from loose cell aggregates to compact spheroids. These findings thus provide comprehensive information on the molecular mechanisms and dynamics of hepatoma spheroid formation.
Lin
Ruei-Zeng
RZ
Institute of Molecular Medicine, National Tsing Hua University, 101 Kuang Fu Road, 2nd Sec., Hsin Chu, 300, Taiwan, Republic of China.
Chou
Li-Fang
LF
Chien
Chi-Chen Michael
CC
Chang
Hwan-You
HY
D015820:Cadherins / Q000502:physiology*; D006528:Carcinoma, Hepatocellular; D002448:Cell Adhesion; D002450:Cell Communication; D045744:Cell Line, Tumor; D005109:Extracellular Matrix / Q000502:physiology; D006801:Humans; D019012:Integrin beta1 / Q000502:physiology*; D018874:Spheroids, Cellular / Q000473:pathology*
D015820:Cadherins; D019012:Integrin beta1