[Diabetes mellitus and pancreatic tumor]

Construction of an "artificial beta cell": Modulation of glucose-stimulated insulin secretion from HepG2 cell

AIM: To construct an "artificial beta cell" which exhibit glucose-stimulated insulin secretion from a human hepatoma cell line.

METHODS: HepG2 cells were infected with recombinant retrovirus carrying glucokinase (gk) gene and mutant proinsulin (mpin) gene, then selectively cultured with G418 to obtain the positive clones. gk gene and mpin gene transcription and expression were identified by radio-immunity, SDS-PAGE, Western-blot and RT-PCR techniques. At last, we tested the dose-response effect of glucose on insulin secretion from the "artificial beta cell", and HepG2 cells with mpin gene transferred as control.

RESULTS: HepG2 cells with gk gene and mpin gene transferred were selectively cultured with G418 and the positive clones were obtained in 3 weeks. Four clones with gk gene and mpin gene expression were selected out by radio-immunity, SDS-PAGE, Western-blot from 20 positive clones. We picked up one clone with strong gk gene and mpin gene expression and named it clone "b". It was proved that the clone "b" had gk gene and mpin gene transcription by RT-PCR. In the clone "b", the differences in the insulin secretion at 0.5 mmol/L and 0.75 mmol/L glucose concentration were not significant (P >0.05), and the differences in the insulin secretion at 2.0 mmol/L, 3.0 mmol/L, 4.0 mmol/L, 5.0 mmol/L and 6.0 mmol/L glucose concentration were also not significant (P >0.05), while there were significant differences in the insulin secretion at the other glucose concentration(P <0.05). In HepG2 cells with mpin gene transferred, there were no significant differences in the insulin secretion at any glucose concentration(P >0.05). The "artificial beta cell" obtained a glucose-stimulated insulin secretion with maximal insulin secretion at 1.75-2 mmol/L glucose concentration.

CONCLUSION: An "artificial beta cell" is successfully constructed.