Figure 2

MIF inhibits glucose-stimulated insulin secretion and contributes to the insulin inhibitory effect of PC cells. (A) Stable shRNA MIF-knockdown (sh-Capan-2, sh-PANC-1) cells and MIF-over expressing cells (MIF-HPDE6) were generated by using lentiviral vectors. Vector controls showed no regulatory effect on MIF expression. (B1&B2) Degree of inhibitory effect on insulin releasing improved with the increasing concentration of MIF from 0 to 100 nmol/L both in PANC-1 (B1) and Capan-2 (B2) cell lines. A most significant drop of insulin secretion level was observed following exposure to MIF at concentrations of 40 nmol/L, reduced to 52% in islets and 46.7% in HIT-T15 cells, respectively, 0 nmol/L rMIF act as control groups. (P <0.01, n = 6). (C1&C2) MIF mediated the inhibitory effect of PC cells on insulin secretion capacity. C1: after indirectly co-cultured with PANC-1 or Capan-2 cells, islet cells showed impaired glucose-stimulated insulin secretion function, shRNA-lentivirus mediated MIF inhibition ameliorated the insulin secretion capacity; the immortalized epithelial cell line HPDE6 decreased insulin secretion a little, while MIF-transgene expressing HPDE6 cells showed a strong inhibitory effect on insulin secretion. C2: after adding supernatants into the culture medium of islet cells, a same effect of MIF was observed. (D1&D2) The same role of MIF was observed in HIT-T15 cells just as it shown in the islet cells. Glc: glucose; *:p<0.01, Student’s t-test. Sh-PANC-1: shRNA MIF-knockdown PANC-1 cell line; Sh-Capan-2: shRNA MIF-knockdown Capan-2 cell line; MIF-HPDE6: MIF-transgene overexpression HPDE6 cell line; pGIZ-PANC-1, pGIZ-Capan-2, and pLOC-HPDE6 are null vector transfected cell lines as controls to exclude the effect of vector on expression of potential genes coding proteins which might regulate insulin releasing.