Angiotensin II differentially regulates annexin V and glypican 6 in MC3T3 cells and B16 melanoma cells

Abstract

Mouse MC3T3 cells (non‐cancerous) and B16 melanoma cells were transfected with a synthetic gene that expresses angiotensin II (Ang II) directly under the control of a CMV promoter. Previous studies using MALDI‐TOF/MS identified several candidate proteins for western blot analysis; Annexin V and Glypican 6 were chosen for further study. Annexin V is a member of a family of calcium‐binding proteins and has been implicated as a regulator of several processes including cell adhesion and apoptosis. One of the earliest events in apoptosis is the externalization of phosphatidylserine (PS) which is translocated from the cytoplasmic side of the plasma membrane to the cell surface soon after the induction of apoptosis, and that the Annexin V protein has a strong, specific affinity for PS. B16 Melanoma cells showed a marked decrease in Annexin V expression; whereas, MC3T3 cells showed a substantial increase in expression. Glypican 6 is a glycophosphotidylinositol anchored heparin sulfate proteoglycan involved in cell growth and division. It is a putative cell surface co‐receptor for growth factors, extracellular matrix proteins and proteases. Like Annexin V, Glypican 6 was down‐regulated in B16 cells and up‐regulated in MC3T3 cells. These results suggest that Ang II has specific growth effects which are differentially regulated in cancer and non‐cancer cells.