Targeted lipidomics between hPheo1 and SDHB KD cells reveal changes in bioactive lipids and PKC with polyamine...

Pheochromocytoma and paraganglioma with a succinate dehydrogenase B subunit (SDHB) pathogenic variant are associated with a significant chance for metastasis. Polyamine pathway inhibitor N1,N11-diethylnorspermine (DENSPM) was previously shown to inhibit cell growth in progenitor cells derived from a human pheochromocytoma (hPheo1). Here, we hypothesized cell death associated with DENSPM treatment due to altered lipid metabolism affects protein kinase C (PKC). From targeted lipidomics analysis, baseline bioactive lipids that are distinct between the hPheo1 WT and SDHB KD cells are PE(P-18:1/16:0), PI(18:1/20:3), LPE(18:0), and LPE(22:4). With DENSPM treatment, the concentrations of multiple plasmanyl phosphatidylethanolamines (PE-O), sphingomyelins (SM), and hexosylceramides (HCER) increased, while the concentrations of several plasmenyl phosphatidylethanolamines (PE-P) were decreased in hPheo1 WT and SDHB KD cells. The differences in PE-Ps, PE-Os, and SMs after DENSPM treatment compared to the vehicle treatment were greater in the SDHB KD cells compared to the hPheo1 WT cells. Basal PKC alpha protein expression was increased in SDHB KD cells compared to hPheo1 WT cells. The protein expression of both PKC alpha and delta was significantly decreased with DENSPM treatment in both cell lines. DENSPM changed pro-caspase-3 and cleaved caspase-3. These data suggest ether phospholipids are biomarkers of DENSPM mediated cell apoptosis through a PKC dependent mechanism.