Establishment of two morphologically distinct PC12 cell lines resistant to 25-OH-cholesterol toxicity

Two novel populations of spontaneous PC12 cell mutants resistant to a toxic concentration of 25-OH-cholesterol (5 microg/ml, 12.5 microM) were isolated and designated as R25R and F25R based on cell morphology. R25R consisted of round cells that were morphologically similar to the parent PC12 cells, and responded to nerve growth factor by extending neurites. F25R was a group of process-bearing flat cells that did not assume a neuronal morphology in the presence of nerve growth factor. These two cell lines also acquired some cross-resistance toward other cholesterol oxides. Nerve growth factor induced prominent voltage-dependent calcium currents in parent PC12 cells and in R25R, but not in F25R. Further experiments indicated that the parent PC12 cells, R25R and F25R exhibited different properties when challenged with a variety of toxic insults, including amphotericin B, serum withdrawal and beta-amyloid protein treatment.