[Overexpression of STAT3 in COS7 cells causes prominent morphological changes]

Signal transducer and activator of transcription 3 (STAT3) plays a central role in mediating signals related to cell growth, differentiation, survival and movement. In this report, the results of immunocytochemistry and Western blot analysis showed that the active form of Stat3 protein existed in COS7 cells. The endogenous Stat3 protein could also induce the expression of m67-sequence-directed reporter genes. The transient transfection of Stat3 cDNA into COS7 cells increased Stat3 protein level and the expression of the reporter gene. The overexpression of Stat3 protein in COS7 cells caused prominent cell morphological changes. These cells had a much larger cell body, extended long processes with branches, lamellipodia and filopodia. These results suggest that Stat3 protein may play important roles in cell adhesion, migration and cytoskeleton reorganization.