Figure 2.

Metformin decreased the growth and viability of rat pituitary tumor cells in vitro, whereas it did not affect the growth of rat myogenic precursors, which are normal, undifferentiated, and rapidly proliferating cells. Rat pituitary tumor cells and rat myogenic precursors differed significantly in some features of their metabolic profile in basal culture conditions: the reductive activity (reduction of the tetrazolium salt MTT within cells) and the ATP content were lower in pituitary tumor cells vs. myogenic precursors. The two cell types also differed significantly in the PDH complex expression levels (PDHE1α protein level), the S6 ribosomal protein levels, and their response to specific metabolic substrates. In this context, short incubations with pyruvate caused an increase of ATP content in myoblasts, without altering the reductive activity. On the other hand, in rat pituitary tumor cells, pyruvate enhanced the sole reductive activity.