Endocrine Abstracts

Introduction: Type 2 diabetes mellitus (T2DM) is characterized by progressive impairment/ loss of pancreatic beta cell function Activation of endoplasmic reticulum (ER) stress by glucose variation has been suggested as an essential step towards beta cell dysfunction. Sodium-glucose co-transporter 2 inhibitors (SGLT2i) are widely used in the treatment of T2DM considering their beneficial cardiometabolic sequalae. In the present study, we aimed to investigate the effect of Empagliflozin on ER stress-induced apoptosis in murine pancreatic islet/beta cell lines.

Material and methods: Hamster HIT-T15 (islet) and mouse BTC-6 (Beta) pancreatic cell lines were maintained in RPMI media, supplemented with 15% FBS.Both cell lines were seeded in 12 well plates and serum starved 16 hrs prior to treatments. After starvation cells were incubated with various concentrations of tunicamycin (5 ug/ml, 10 ug/ml, 20 ug/ml) or Empagliflozin (10⁻⁸, 10⁻⁹ and 10⁻¹⁰ M) alone or co-incubated with both agents simultaneously. The expression levels of SGLT-1, SGLT-2, GRP-94, Bip, PERK, elf-2α and CHOP were measured by quantitative real time PCR while protein levels of GRP-94, Bip, p-PERK, elf-2α, P- elf-2α and CHOP were measured by western blotting. Cell proliferation and apoptosis were measured by XTT and Annexin V FITC assays respectively.

Results: SGLT-1 mRNA was detected only in BTC-6 cells while SGLT-2 mRNA was not detected in either cell line. Incubation of BTC-6 cells, but not HIT-T15, with Empagliflozin (10⁻⁸, 10⁻⁹ M. P<0.05) resulted in significant increase in cell proliferation compared to untreated cells. Both Hit-15 and BTC-6 cells were sensitive to tunicamycin and underwent significant cell death after 48h treatment (P<0.01). Co-incubation of cells with Empagliflozin significantly inhibited tunicamycin (5 ug/ml and 10 ug/ml) -induced cell apoptosis with more robust effect observed in BTC-6 cell line (P<0.01) as compared with HIT-T15 cell line. Particularly, co-incubation of BTC-6 cells with tunacamycin and Empagliflozin reduced (ER) stress-induced apoptosis through down regulation of p-elf-2α (P<0.01) and CHOP (P<0.01) while in HIT-T15 the ER stress was reduced through reduction of Bip (P<0.01), p-PERK (P<0.05) and CHOP (P<0.05) protein expression. These results were in line with mRNA expression results.

Conclusion: Our data indicate that Empagliflozin increases proliferation and reduces cell apoptosis in beta-pancreatic cells, at least in part, via reducing ER stress. The effect of Empagliflozin on beta-cell apoptosis/survival could be mediated through SGLT-1. More studies are needed to verify the efficacy of this class of drugs in maintenance of pancreatic cells survival and function.