Streptozotocin and Alloxan-based Selection Improves Toxin Resistance of Insulin-Producing RINm Cells

The aim of our study was to develop a method forselection of subpopulations of insulin producingRINm cells with higher resistance to beta cell toxins.Cells, resistant to streptozotocin (RINmS) andalloxan (RINmA), were obtained by repeated exposureof parental RINm cells to these two toxins,while the defense capacity, was estimated by theMTT colorimetric method, and [³H]-thymidine incorporationassay. We found that RINmS andRINmA displayed higher resistance to both streptozotocin(STZ) and alloxan (AL) when compared tothe parental RINm cells. In contrast, no differencesin sensitivity to hydrogen peroxide were foundbetween toxin selected and parental cells. Partialprotection from the toxic effect of STZ and AL wasobtained only in the parental RINm cells afterpreincubation of cells with the unmetabolizable 3-O-methyl-glucose. The possibility that GLUT-2 isinvolved in cell sensitivity to toxins was confirmedby Western blot analysis, which showed higherexpression of GLUT-2 in parental RINm comparedto RINmS and RINmA cells. In addition to thehigher cell defense property evidenced in theselected cells, we also found higher insulin contentand insulin secretion in both RINmS and RINmAcells when compared to the parental RINm cells. Inconclusion, STZ and AL treatment can be used forselection of cell sub-populations with higher cell defense properties and hormone production. Thedifferent GLUT-2 expression in parental and resistant cells suggest involvement of GLUT-2 inmechanisms of cell response to different toxins.