Squamosamide Derivative FLZ Protects Pancreatic β-Cells from Glucotoxicity by Stimulating Akt-FOXO1 Pathway

Figure 4

FLZ acts via stimulation of Akt. (a) INS-1E cells were treated with 0.1 μM, 1 μM, and 10 μM FLZ for 8 h. Expression of p-Akt and total Akt protein was determined by western blot. Mean ± S.E.M. of three separate experiments. Intensities of p-Akt protein expression were quantified, normalized against the level of total Akt, and expressed as fold of protein abundance in INS-1E cells treated with DMSO. versus control. (b) INS-1E cells were cultured at G11.1 or G30 for 4 days. Cells were treated without or with 10 μM FLZ. Expression of p-Akt and total Akt protein was determined by western blot. Mean ± S.E.M. of seven separate experiments. versus the value at G11.1; versus the value at G30 without FLZ. (c) Cell viability was assessed in INS-1E cells being cultured at G11.1 and G30 for 4 days. Cells were treated without or with 10 μM FLZ or simultaneous addition of 10 μM FLZ and 50 nM MK-2206. Values were expressed as percentage of cell viability at G11.1. Data are means ± S.E.M. of 3-4 independent experiments. versus the value at G5.5; versus the value at G30 without FLZ; versus the value at G30 with FLZ. (d) Insulin content was assayed without or with 10 μM FLZ or simultaneous addition of 10 μM FLZ and 50 nM MK-2206. Values are normalized against total protein. Data are means ± S.E.M. of 4–12 experiments. versus the value at G5.5; versus the value at G30 without FLZ; versus the value at G30 with FLZ. (e) Insulin secretion was assayed in INS-1E cells treated without or with 10 μM FLZ or simultaneous addition of 10 μM FLZ and 50 nM MK-2206. Values were normalized against total protein. Data are mean ± S.E.M. of 5–16 separate experiments. versus the value at G5.5; versus the value at G30 without FLZ; versus the value at G30 with FLZ.

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