Thiamine pyrophosphate (TPP) content, activities of
thiamine pyrophosphokinase (TPKase),
thiamine pyrophosphatase,
transketolase (TK),
pyruvate (PDG) and oxoglutarate
dehydrogenases (OGDG) were measured in the liver and cells of Ehrlich
ascites carcinoma (EAC) on the 5th, 10th and 15th day after
transplantation of the
tumor to mice fed a
thiamine-deficient diet. The TPP level gradually decreased in the liver of
tumor-bearing mice but remained constant in
tumor cells (1.06 +/- 0.02 microgram/g tissue). Deprivation of dietary
thiamine lowered the liver TPP level even to a greater extent, and subsequent daily 10 micrograms
thiamine/mouse
injections did not restore it. The TPKase activity in the liver of mice with EAC decreased by 24% and in
thiamine deficiency, by 44%. The liver PDG, OGDG and TK activities were reduced but slightly in mice with EAC, whereas
thiamine deprivation resulted in a decrease of the
enzyme activities: PDG by 60%, OGDG by 25% and TK by 45%. TK activity in
tumor cells was 90 mumol S-7-P/g tissue/h, and the TPP effect amounted to 24%.
Thiamine deprivation decreased the TK activity by 45% and raised the TPP effect up to 180%.
Thiamine injections restored the TK activity in
tumor cells and reduced the TPP effect.