Measurement of cell viability (24 to 72 hours) and apoptosis in response to different biguanides alone or in response to the combination of metformin with somatostatin analogs (octreotide or pasireotide) in primary PitNET cell cultures and pituitary cell lines. (A) Effect of MF (10 mM), BF (5 mM), and PF (5 mM) on cell viability in primary ACTHoma cell cultures (MF: n = 10; BF: n = 6; PF: n = 5) and in the corticotropinoma AtT-20 cell line (MF: n = 9; BF: n = 6; PF: n = 7), measured by Alamar blue reduction. (B) Effect of MF alone or in combination with octreotide or pasireotide on cell viability in ACTHomas (n = 3). (C) Effect of MF, BF, and PF in primary GHoma cell cultures (MF: n = 9; BF and PF: n = 4) and in the somatotropinoma GH3 cell line (n = 4). (D) Effect of MF alone or in combination with octreotide or pasireotide on cell viability in GHomas (n = 5). (E) Effect of biguanides in primary NFPA cell cultures (MF: n = 11; BF: n = 7; PF: n = 8). (F) Effect of MF alone or in combination with octreotide or pasireotide on cell viability in NFPAs (n = 2). (G) Effect of biguanides in primary PRLoma cell cultures (n = 3). (H) Effect of MF on apoptosis (24-hour treatment) in primary GHoma cell cultures measured by Caspase-Glo 3/7 assay. Data are expressed as percentage of vehicle-treated controls (set at 100%) within experiments. Values represent the mean ± SEM. Asterisks (*P < 0.05; **P < 0.01; ***P < 0.001) indicate statistically significant differences. In cases where fewer than three experiments were performed, no significance tests were performed.