Vitamin B6 Effects on the Growth of Morris Hepatomas and the Development of Enzymatic Activity

Expression of Hormonally Induced Tyrosine Aminotransferase in Host Liver and Morris Hepatoma No. 7777 During Cofactor Depletion

“…Furtherm ore, a particulate liver fraction com po nent has been described which interconverts T A T multiple forms and whose catalytic action is pH dependent [25,26]. It is possible that horm onal effects on T A T expression could reflect effects on the liver factor [25,26], As suggested previously [23], this could also be the case with T A T derepression seen during cofactor depletion, i. e. TA T derepression may reflect a cofactor influence on the liver factor [25. 26].…”

“…T hat cofactor lack results in TAT derepression was also shown in the liver of animals without hepatom as [5]. M oreover, TA T derepression was further verified by the im m unoprécipitation of the resolved gel proteins with antibody prepared against highly purified (> 3 ,0 0 0 fold) hepatic tyrosine am inotrans ferase [22,23], Since lack of cofactor results in inhibition of tum or growth [3, 7 -1 0 ] and also enzyme derepression [5,20,22,23] it is suggested herewith that the vitamin exercises a type of regulation over enzyme expression which could be essential for norm al tum or growth. It has been reported that the proportion of each T A T form could be varied by varying the pH of the homogenising medium [24].…”

Activation and Protection from 5-Fluorodeoxyuridylate Inactivation of Mammalian Thymidylate Synthetase by Pyridoxal 5'-Phosphate

“…It has been reported that the growth of hepatocellular carcinomas and neoplasms, in general, is significantly impaired in the absence of pyridoxine (1)(2)(3). In addition, it has been reported that the vitamin reverses the effects of 5-fluorouracil administration on the growth of sarcoma 180 (4).…”