Choline-phospholipids inter-conversion is altered in elderly patients with prostate cancer.

Abstract

Choline is an important source of phospholipids and methyl groups in mammalian cells. High demands for methyl and phospholipids in malignant cells suggest that choline metabolism may be disturbed in patients with cancer. This case-control study investigated differences in concentrations of choline metabolites between 80 elderly men (age≥65 years) with prostate cancer (PCa) and 51 men with benign prostatic hyperplasia (BPH). Plasma/serum concentrations of free choline, betaine, dimethylglycine, folate, total homocysteine (tHcy), cystathionine, methylmalonic acid, S-adenosyl homocysteine (SAH), S-adenosyl methionine (SAM), and phospholipids were measured. Men with BPH and those with PCa showed no significant differences in the concentrations of free choline (median=9.7 vs. 10.0μmol/L), folate (17.4 vs. 19.8nmol/L), tHcy (16.0 vs. 16.2μmol/L), SAH (18.8 vs. 18.2nmol/L), and phosphatidylcholine (1634 vs. 1610μmol/L). The concentrations of methylmalonic acid were lower in men with PCa (203 vs. 228nmol/L) but the difference was not significant after adjusting for age. Sphingomyelin species (16:0, 18:0, 18:1, 20:0, 22:0, 22; 1, 23:0, 23:1, 24:0, 24:1, and 24:2) were significantly lower in men with PCa than in the controls (6-16% differences). Multiple regression analyses showed that the presence of PCa, statin use, choline, age, cystathionine, and methylmalonic acid were significant negative determinant of sphingomyelins, whereas phosphatidylcholine was a strong positive determinant. The current results support systemic alterations in phospholipids metabolism in PCa. We report on a significant decrease in plasma concentrations of sphingomyelin in elderly patients with PCa and in users of statins. The PCa-associated low sphingomyelin showed a synergy with the effect of statins. The presence of PCa was not associated with significant changes in plasma concentrations of choline or methyl metabolites. However, changes in choline absorption and tissue uptake cannot be ruled out in this study.