VITAMIN-B-6 AND CANCER - SYNTHESIS AND OCCURRENCE OF -N-6-DIETHYLTHIOETHER-N-PYRIDOXIMINE-5'-PHOSPHATE, A CIRCULATING HUMAN TUMOR-MARKER

In the course of studies aimed at deciphering the metabolic transforma tions of [3,4-C-14] and [H-3]C6-pyridoxine hydrochloride by tumor-bear ing rats and tumor cells in culture, biosynthesis of a novel labeled p roduct,vas observed. Its production began with the onset of tumor grow th and increased as cell proliferation increased, Chemical, enzymatic, precursor labeling, and analytical tests on the isolated product indi cated this product as e-N-6-diethylthioether-N-pyridoximine-5'-phospha te (compound 1). In confirmation, the chemical synthesis and character ization of compound 1 are presented in this study, In addition, blood samples from 28 normal subjects, 28 cancer patients with different mal ignancies, and 39 patients with a variety of other than cancer ailment s were screened for compound 1 on a blind basis using reverse phase io n-paired high-performance liquid chromatography. The results show that the level of the vitamin B-6 conjugate in the circulation of control subjects, cancer patients in remission, and patients with other diseas es was only minimal. Canter patients with active disease had 3-4-fold higher levels (P < 0.00001). Our results also confirm previous finding s regarding the structure of compound 1 and show its potential value a s a circulating human tumor marker that could be successfully used for cancer detection.