title: Cytotoxicity of alkyl-lysophospholipid derivatives and low-alkyl-cleavage enzyme activities in rat brain tumor cells.
abstract: Alkyl-lysophospholipids (ALP) and related derivatives inhibited the in vitro incorporation of [3H]thymidine into seven different permanent cell lines derived from rat brain tumors. The cytostatic effect of ALP was dependent on dosage and incubation time. Naturally occurring 2-lysophosphatidylcholine did not exhibit cytostatic effects; under these conditions, the incorporation rates of [3H]thymidine were generally more than 100% of the controls. The trypan blue dye exclusion test, which was used to assess severe cell damage, correlated with the extent that [3H]thymidine incorporation was inhibited by ALP. Preincubation of ALP (rac-1-octadecyl-lyso-glycero-3-phosphocholine) for more than 8 min with a tetrahydropteridine-dependent O-alkyl cleavage enzyme preparation from rat liver microsomes destroyed almost all of the cytotoxic properties of ALP when tested at a concentration that previously inhibited tumor growth by more than 50%. [3H]Thymidine incorporation rates were greater than 100% for astrocytoma cells incubated with ALP after exposure to the alkyl cleavage enzyme. Comparison of the microsomal activities of the tetrahydropteridine-dependent alkyl-cleavage enzyme present in astrocytoma 78-FR-G-299 cells and the pleomorphic glioma 78-FR-G-219/S4 cells to that found in normal skin fibroblasts and rat livers revealed a markedly reduced activity in the neoplastic cell lines. Moreover, those tumor cells that were more resistant to ALP cytotoxicity (pleomorphic glioma, 78-FR-G-219/S4) had a 3-fold higher tetrahydropteridine-dependent cleavage activity than a more cytotoxic sensitive line (astrocytoma cells, 78-FR-G-299). Our results indicate that the low-alkyl-cleavage enzyme activities in these neoplastic cells in comparison to normal cells might be a factor in explaining the relatively high cytotoxicity of ALP in tumor cells.
mesh_terms: D000818:Animals; D001254:Astrocytoma / Q000503:physiopathology; D001932:Brain Neoplasms / Q000503:physiopathology*; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D004261:DNA Replication / Q000187:drug effects; D005910:Glioma / Q000503:physiopathology; D007700:Kinetics; D008244:Lysophosphatidylcholines / Q000494:pharmacology*; D008246:Lysophospholipids; D009374:Neoplasms, Experimental / Q000503:physiopathology; D010743:Phospholipids / Q000494:pharmacology*; D051381:Rats; D013329:Structure-Activity Relationship
chemical_list: D008244:Lysophosphatidylcholines; D008246:Lysophospholipids; D010743:Phospholipids