Researchers from the University of North Carolina have identified a protein that may inhibit cellular movement, or migration.
The protein, CIB1, or calcium and integrin-binding protein 1, was originally discovered at UNC in 1997 as a blood platelet protein that may play a role in clotting.
Cell migration belongs to the most rudimentary of cellular functions that allow processes such as fetal development, new blood vessel formation and wound healing to occur in humans. Increased tumor cell migration also is one of the hallmarks of highly aggressive, rapidly spreading cancer tumors.
The study appears in the August issue of The Journal of Cell Biology.
The study indicates that CIB1 inhibits cell migration by binding to and activating a protein called PAK1, or p21-activated kinase, in cancer cells. When CIB1 activates PAK1, this kinase then inhibits cell migration by adding a phosphate group to a host of other proteins in the cell.
Thus, the study suggests that CIB1 may be a likely target for new drug development aimed at decreasing tumor metastasis, or spread, throughout the body.
CIB1 plays a prominent role in the activation of PAK1 and potentially may be another important player in the regulation of this kinase. The other activators of PAK1 include relatives of the notorious Ras family of tumor promoters, the GTPases Rac and Cdc42. CIB1 activation of PAK1, however, is different from these GTPases.
In illustrating the role that CIB1 plays in cell migration and PAK1 activation, the authors used a new method known as RNAi or RNA interference to knock down or reduce CIB1 expression in various cell lines. Cells with less CIB1 had less PAK1 activation and migrated faster. The authors also showed that the more CIB1 these cells had, the less likely they were to move.
Medindia on RNAi: Further information
RNAi: RNA interference is a technique of gene silencing that is used to study the effect of absence of a gene, by causing disruption to its expression, on an animal or a plant.