THE EFFECT OF ESTROGEN ABLATION ON THE PHOSPHOLIPID METABOLITE CONTENT OF PRIMARY AND TRANSPLANTED RAT MAMMARY-TUMORS

The concentration of phospholipid metabolites was determined in chemic al extracts from two types of rat mammary tumours and compared with pr oliferation data (S-phase fraction). One of the tumours was an oestrog en-sensitive transplanted tumour. In this tumour the concentration of phosphocholine (PC) and glycerophosphorylcholine (GPC) correlated stro ngly with the S-phase fraction but not with the number of cells active ly synthesizing DNA. Oestrogen ablation resulted in tumour regression. Regressing tumours contained less PC and more GPC than those actively growing. The other tumour was induced in rats by intravenous administ ration of N-methyl N-nitrosourea. Phosphoethanolamine (PE), PC and GPC levels were not associated with the S-phase fraction in this tumour. Oestrogen ablation resulted in tumour regression. There was no signifi cant difference between the regressing and growing tumours in PE, PC o r GPC content.