Oxidized low-density lipoprotein (oxLDL) induces cell death in neuroblastoma and survival autophagy in schwannoma cells

Abstract

Oxidized low-density lipoprotein (oxLDL) induces apoptosis or autophagy in dependence on the cell type. We here investigated the effect of oxLDL on the B104 neuroblastoma and RN22 schwannoma cells being popular in neuroscience research. Cells were cultivated with and without oxLDL. To generate oxLDL, we added 50 μg/ml nLDL and 50 μM CuSO(4) into the culture medium. After a 24-h-long treatment, oxLDL was detectable in media from both cell culture types and its concentration was approximately 16 μg/ml. In the oxLDL-treated B104 neuroblastoma cell cultures 75% cells died after the 24-h exposure. The intact cells showed impaired mitochondria at the ultrastructural level. Western blot analysis revealed the increased expression of AIF 57 kDa (AIF(57)) protein, as a sign of caspase-independent cell death. In RN22 schwannoma cell cultures, oxLDL did not have any effect on cleaved caspase-3 and AIF(57) protein levels indicating absence of cell death. Treated RN22 schwannoma cells underwent survival autophagy by forming conspicuous autophagosomes and by processing LC3-I into LC3-II protein. Collectively, oxLDL induces AIF-dependent cell death in B104 neuroblastoma cells whereas in RN22 schwannoma cells enhanced signs of survival autophagy are noted.