Figure 1. 6F2 cells are resistant to palmitate-induced lipotoxicity.

(A) Wild type (WT) and mutant 6F2 CHO cells were untreated (UT) or supplemented with 500 μM palmitate for 48h or with 80 nM staurosporine, 2 μM actinomycin D, or 10 μM camptothecin for 24 h. Cell death was quantified by propidium iodide (PI) staining and flow cytometry on 10⁴ cells/sample. (B) WT and 6F2 cells were incubated with ¹⁴C-palmitate for 1 min. Uptake of labeled palmitate was assessed by scintillation counting. (C) WT and 6F2 cells were incubated with ³H-palmitate for 2 h. ³H₂O production as a measure of fatty acid oxidation was assessed by scintillation counting. (D) WT and 6F2 cells were treated with palmitate for indicated times, or with the ER stress inducers, tunicamycin (Tm, 2.5 μg/ml) or thapsigargin (Tg, 1 μM) for 6 h. grp78 expression was analyzed by quantitative real-time PCR (qRT-PCR) and normalized to β-actin expression. (E) WT and 6F2 cells were treated with palmitate for indicated times or with 500 μM H₂O₂ for 1 h. ROS generation was quantified by CM-H₂DCFDA (DCF) labeling and flow cytometry on 10⁴ cells/sample. (F) WT and 6F2 cells were UT or treated with 2.3 mM H₂O₂ for 20 h. Cell death was quantified by PI staining and flow cytometry on 10⁴ cells/sample. All data expressed as mean ± SE for 3 independent experiments. * p < 0.01 for mutant 6F2 vs. WT; n.s., not significant. (See also supplemental Figure 1.)