Free and Acetylated Polyamines in Cyst Fluids of Brain Tumors

Abstract

Increased levels of polyamines in rapidly growing tissues have been demonstrated, and recently rather high concentrations of conjugated polyamines such as N1-acetylspermidine have been found in certain malignant tumors. The purpose of this study is to analyze concentrations of free and conjugated polyamines in cyst fluids of brain tumors. Materials used were cyst fluids obtained in brain tumor surgery: 25 specimens were from cysts of benign brain tumors (acoustic neurinoma, 8 cases; craniopharyngioma, 7 cases; hemangioblastoma, 6 cases; meningioma, 2 cases; pituitary adenoma, 2 cases) and 17 specimens from malignant brain tumors (malignant astrocytoma, 2 cases; glioblastoma, 15 cases). After deproteinization of cyst fluids with 6N perchloric acid, polyamine levels were measured with the use of high-performance liquid chromatography (HPLC) using cation-exchange resin before and after acid hydrolysis. Polyamines separated in various fractions by HPLC were further analyzed before and after acid hydrolysis. The cyst fluids contained putrescine, spermidine, N1-acetylspermidine, and several other minor peaks. The levels of N1-acetylspermidine were much higher in cyst fluids of malignant brain tumors than in benign brain tumors. Higher concentrations of putrescine were also demonstrated in cyst fluids of malignant brain tumors. The increase in spermidine contents after acid hydrolysis was more than that which was derived from N1-acetylspermidine alone. In fact, some fractions other than the N1-acetylspermidine fractions yielded putrescine and/or spermidine upon acid hydrolysis. These data suggest that not only N1-acetylspermidine but also other polyamine conjugates are present in cyst fluids of brain tumors. Presumably N1-acetylspermidine and other conjugated forms are preferentially released into cyst fluids from malignant tumor tissues. The present study shows that not only putrescine but also N1-acetylspermidine in cyst fluids are promising markers of brain tumors.