Effects of genistein on insulin pathway-related genes in mouse differentiated myoblast C2C12 cell line: evidence for two independent modes of action.

INTRODUCTION: Genistein (plant isoflavone) is a well-known anti-cancer drug with estrogenic-like properties. Genistein also regulates sugar and lipid metabolism; thus, it has anti-diabetic properties. The aim of the study was to evaluate in vitro effects of genistein on glucose transport, fatty acids oxidation, activation of PKB, and expression of genes related to insulin pathway in differentiated myoblast C2C12 mouse cell line.

MATERIAL AND METHODS: Differentiated myoblast C2C12 mouse cell line was used to assess the effects of different genistein concentrations on glucose transport and fatty acids oxidation measured by radioactivity technique, activation of PKB, and expression of selected genes related to insulin signaling pathway (IR-a, IR-b, IRS-1, PKB, GLUT-4, PP2A, SH-PTP2) at the mRNA and protein levels. Cells were incubated with various concentrations of genistein under standard conditions for 0-48 hours.

RESULTS: Genistein in low concentrations (0.1-1 μM) significantly increased glucose transport and decreased fatty acids oxidation in C2C12 cells after 48 h of incubation. High concentration of genistein (50 μM) had the opposite effect. Genistein stimulated PKB phosphorylation during the first 5-10 minutes of incubation. There was no significant impact on the protein expression of selected genes (IR-a, IR-b, IRS-1, PKB, GLUT-4, PP2A-Ca, ER-a and ER-b) after 48 h treatment. We observed inverse correlation between genistein concentration and the expression of SH-PTP2 protein. Genistein affected the expression pattern of mRNAs for genes related to the insulin pathway, however, not the expression of the encoded proteins.

CONCLUSIONS: The results of this study showed that depending on the concentration and time of incubation genistein significantly affects glucose and lipid metabolism and at low concentration modifies expression pattern of a few genes in C2C12 cells.