[Effects of exogenerous nucleotides on the apoptosis of intestinal epithelial cells IEC-6].

OBJECTIVE: To investigate the effects of exogenous nucleotides on apoptosis of a normal rat small intestinal epithelial cell line, IEC-6. METHODS: Cultured IEC-6 cells were treated by four kinds of monophosphate nucleotides and their mixture prepared according to their composition in human milk, then the cell apoptosis was determined by flow cytometry measurement, morphologic characterization, and electron-microscope observation. RESULTS: IEC-6 cells treated with AMP or GMP showed a apotosis peak in flow cytometry measurement, but only AMP produce typical apoptosis characteristics in electron-microscope observation. Pyrimidine nucleotides (UMP and CMP)and nucleotides mixture could not induce apoptosis. However, UMP could significantly eliminate the apoptosis-inducing effects of AMP or GMP. CONCLUSION: Purine nucleotides induce apoptosis of IEC-6, inducing effects of purine nucleotides. pyrimidine nucleotides UMP could abolish the apoptosis-inducing effects of purine nucleotides.

[Sensitivity comparison of DNA damage and repair capacity in TK6 and WTK1 cells].

OBJECTIVE: Explore the mechanisms of DNA damage and repair capacity in TK6 and WTK1 cells that are derived from the same parental cell line WI-L2 (tk+/+) human diploid lymphoblastoid cells but are different in their p53 gene status. METHODS: The TK6 and WTK1 cells treated with H2O2 were detected by single cell gel electrophoresis. Then a comparison was made on the comet cell rate, comet cell tail length and p53 protein expression level between TK6 and WTK1. RESULTS: TK6 was more sensitive to DNA damage and its repair capacity was more quick and effective when compared with WTK1. Both TK6 and WTK1 cells showed effective post-damage repair capacity in incubation time of 0.5 h to 1 h. The background level of P53 protein in WTK1 was higher than that in TK6, but the level of P53 protein in H2O2-treated TK6 increased significantly higher than that in H2O2-treated WTK1. CONCLUSION: TK6 and WTK1 cells serve as a good biological experiment system for DNA damage sensitivity and repair capacity researches in the field of toxicology. TK6 is more sensitive to DNA damage, and it increases faster and higher than WTK1 after DNA being damaged. A possible explanation is that TK6 cell is of the p53 gene wild-type and WTK1 cell is of the mutant-type and they make different responses to the same chemical.

Effects of fat-soluble extracts from vegetable powder and beta-carotene on proliferation and apoptosis of lung cancer cell YTMLC-90.

OBJECTIVE: The aim of this investigation was to study the effects of fat-soluble extracts from vegetable powder (FEFVP) and beta-carotene on the proliferation and apoptosis of cultured YTMLC-90 lung cancer cells. METHODS: The lung cancer cells were continuously exposed to a broad range of concentration of FEFVP and beta-carotene. The proliferation was evaluated in MTT test. The induction of apoptosis was evaluated by morphological change, DNA fragmentation analysis, and DNA content analysis combined with flow cytometric analysis. RESULTS: Both FEFVP and beta-carotene were found to inhibit cell proliferation and to induce morphologic changes consistent with apoptosis in YTMLC-90 cancer cells, including cellular shrinkage, chromatin condensation and nuclear fragmentation. DNA agarose gel electrophoresis showed DNA fragmentation 'ladder'. Flow cytometric analysis revealed decreased DNA content and the presence of a sub-G1 apoptotic peak. CONCLUSION: These findings are consistent with the induction of apoptosis. Moreover, the effects of FEFVP are stronger than those of beta-carotene. FEFVP inhibits the growth of YTMLC-90 probably via the induction of apoptosis cancer cells.