[Comparison of TK gene mutation assay in TK6 and TK6-E6 cell induced by vinblastin and colcemid].

OBJECTIVE: To compare TK gene mutation assay in human lymphoblastoid cell lines TK6 and TK6-E6 induced by vinblastin and colcemid. METHODS: Regular TK gene mutation assays were experimented to detect cytotoxicity and mutation frequency at tk locus after TK6 and TK6-E6 human lymphoblastoid cells were treated with vinblastin and colcemid for 24h. RESULTS: Relative survival (RS%) and Relative suspension growth (RSG%) of TK6 and TK6-E6 cells decreased when concentrations of vinblastin and colcemid increased. RS% and RSG% of TK6-E6 cells were higher than that of TK6 cells at the same doses. TK6 and TK6-E6 cells both were induced by vinblastin and colcemid. The TK6-E6's nature mutation frequency, induced mutation frequency and percentage of slow growth mutant (SG%) were lower than TK6' s at the same dose except group CCM 5.0ng/ml in MF and group CCM 0.625ng/ml in SC%. CONCLUSION: Both TK6 and TK6-E6 cell lines can be used in TK gene mutation assay, but TK6-E6 cell line was recommended to be used in the assay for its less quantity and doubling time.

[The tk gene mutation analysis in WTK1 cell line by multiplex PCR].

OBJECTIVE: To explore the tk gene mutation spectrum in spontaneous and induced WTK1 mutants. METHODS: After exposure to methyl methanesulfonate (MMS), mitomycin (MMC) or sodiam azide (NaN3), spontaneously-arising and induced mutants of WTK1 cell line were selected. The spectrum and hotspot of tk gene mutation were analyzed by multiplex PCR. RESULTS: Three chemicals used in this study induced tk mutation frequency (MF) to increase significantly in a dose-dependent manner; most of the analyzed mutants had lost exon 4 and exon 5-7. CONCLUSION: Three chemicals have mutagenic effect on WTK1 cell line, and obvious hotspot exists in tk gene mutation.

[Analysis of loss of heterozygosity induced by vinblastine at tk locus in human lymphoblastoid cell line TK6].

OBJECTIVE: To establish TK gene mutation assay using human lymphoblastoid cell line TK6 and to study the genotoxic mechanism of Vinblastine (VBL). METHODS: TK6 cells were treated with Vinblastine at different concentrations (0.625 ng/mL, 1.250 ng/mL, 2.500 ng/mL and 5.000 ng/mL)for 24 h and TK gene mutation assay were experimented. Relative survival (RS%), relative suspension growth (RSG%), mutation frequency at tk locus and percentages of slow growth mutant (SC%) were detected and loss of heterozygosity (LOH) of mutants were analyzed. RESULTS: A decreased RS% and RSG% and an increased mutation frequency at tk locus were observed in a dose-dependent manner when the TK6 cells were treated with 0.625, 1.250, 2.500 and 5.000 ng/mL of Vinblastine respectively for 24 h. The result demenstrated that about 96.4% of Vinblastine-induced mutants were LOH. Among them, 39.3% were hemi-LOH and 57.1% were homo-LOH respectively. CONCLUSION: TK6 cell line can be used to detect the genotoxicity of Vinblastine and LOH was the major mutation events in Vinblastine-induced mutants.

[TK locus mutation assay: comparison of L5178Y and TK6 cell lines].

OBJECTIVE: To compare the advantages and disadvantages of utilizing L5178Y and TK6 cell lines in the TK locus mutation assay. METHODS: The two cell lines were used for detecting and assessing the mutability of four chemicals (MMS, EMS, MMC and KCl); the microwell method of TK locus mutation assay was adopted. RESULTS: The two cell lines brought about similar results in the study. The tolerance of TK6 to all four chemicals was lower than that of L5178Y, and all the relative mutation indices of TK6 were higher than those of L5178Y. CONCLUSION: Each of the two cell lines has its own strong points; nevertheless, the authors recommend the applications of TK6 cell in the assay system since this cell line comes from human.