[Experimental study of biochemical modulation of 5-fluorouracil with l-leucovorin against human esophageal cancer].
Potentiation of cytotoxic effects of 5-fluorouracil (5-FU) were investigated by simultaneous or sequential combination of l-leucovorin (LV) against human esophageal cancer cell line (TE-1, TE-2) and 23 human clinical cancer samples in vitro. LV enhanced the cytotoxic effects of 5-FU on human esophageal cancer cell line as a dose dependent manner, and increased the cytotoxic effect of 5-FU about 1.5-fold with 10 microM and about 2-fold with 100 microM. The incubation time did not affect the effects. The potentiation with LV was also demonstrated against human clinical cancer samples, and the cytotoxic effects of 5-FU increased 7.6% in esophageal cancer, 20.9% in gastric cancer and 25.5% in colorectal cancer. As a result, the potentiating effects of LV against 5-FU seemed to be limited on human esophageal cancer.