iTRAQ-based HepaRG Membrane Proteomics

HepaRG cell, a stabilized bipotent liver progenitor cell line, exhibits hepatocyte functions only after differentiation. However, the mechanism of transition from non-differentiated to differentiated states, accompanied by proliferation and migration, is poorly understood. Little information exists for proteins involved in this process, particularly those residing in the plasma membrane. In this study, the plasma membrane protein expression change of HepaRG cell before and after differentiation were systematically analyzed using an iTRAQ labeled quantitative membrane proteomics approach. A total of 70 membrane proteins were identified to be differentially expressed. Function and disease clustering analysis showed that 11 of these proteins are involved in migration. Two key factors (MMP-14 and OCLN) were validated by qRT-PCR and Western Blot. Blockade of MMP-14, an extracellular matrix metalloprotease, by monoclonal antibody in a wound healing assay further demonstrated the importance of this protein in tumor cell migration. Even further, the MMP-14 expression correlation with HCC is confirmed by HCC cell lines and tissue samples.