Effect of B6 deficiency on hepatoma 7794A growth rate: Activities of tyrosine transaminase and serine dehydratase before and after induction by hydrocortisone

Effect of Pyridoxine on the Growth of Morris Hepatoma No. 7288Ctc and Enzyme Activity

“…A highly statistical significant difference between average hepatoma weights grown in animals fed the pyridoxine free diet ad libitum and hepatomas grown in pair-fed controls receiving the same amount of the same diet supplemented with pyridoxine was found, P. < 0.001 (table I). Results similar to these were also found with four other Morris hepatoma lines [2,3], In addition, regression of lymphosarcoma in mice in the absence of dietary pyridoxine has also been reported [16,17], Whether inhibition of tumor growth is a direct result of the vitamin's absence from the diet or is due to other factors mani fested during the state of deficiency is not known and current tests are directed to this aim. Nevertheless, albeit the operating mechanism(s), the data demonstrate a significant reduction in tumor weight during pyridoxine depletion.…”

“…After 22 days, they were inoculated with tumor cells in the muscle of each hind leg and were sacrificed 16 days later. Livers and tumors were removed, weighed [2,3,5,6] and TAT activity measured by the method of Diamondstone [14], as described [8], Protein was measured by the method of Lowry [15]. Other details have been reported [5][6][7]9],…”

“…Buffalo strain female rats were purchased from Simonsen Laboratories (Gilroy, California) and were handled as reported previously [2], Animals were fed ad libitum a pyridoxine free diet or were pair-fed the same diet with pyridoxine added [2][3][4], Diets were prepared commercially according to French [13] by contract with Teklad Mills, Inc., Madison, Wisconsin. In pair-feeding, animals with the same weight and age were matched in "pairs".…”

“…It is also accepted that pyridoxal phosphate is the coenzyme of many classes of enzymes f 1 ]. Recent studies in this laboratory have shown that absence of pyridoxine from the diet inhibits significantly the growth of Morris hepatomas and alters the specific activity level of certain enzymes [2][3][4][5][6], Further, hormonal enzyme induction in animals with or without tumors is adversely affected by cofactor depletion [7][8][9], Other in vestigators have also reported alterations of enzyme activity levels in the absence of dietary pyridoxine [10][11][12], The ef fects of dietary pyridoxine on the growth of the poorly dif ferentiated Morris hepatoma no. 7288Ctc and the activity of tyrosine aminotransferase (TAT), a pyridoxal phosphaterequiring enzyme, were examined in this study.…”

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

“…The response of the enzyme to hydrocortisone varies in different Morris hepatom a lines from com plete unresponsiveness to significant increases [1,2], The pattern of its horm onal induction is drastically altered in host liver and this hepatom a [3], In animals without tum ors, cofac tor depletion, i. e. pyridoxine depletion, alters the am inotrans ferase horm onal induction pattern and effects further resolu tion of the enzyme on electrophoresis in polyacrylamide gel [4,5,6], Further, lack of dietary pyridoxine significantly inhibits the growth of several M orris hepatom a lines, including that of hepatom a No. 7777 [3,[7][8][9][10], R at liver cytoplasmic tyrosine am inotransferase consists of multiple forms which may be affected by horm onal adm inistration [11][12][13][14][15][16][17][18][19]. W hether cofactor depletion affects the expression of the enzyme in hepatom a-bearing animals has not been investigated.…”