Response of human REV3 gene to gastric cancer inducing carcinogen N-methyl-N’-nitro-N-nitrosoguanidine and its role in mutagenesis

Table 1 Detection of the spontaneous and induced mutation frequency at HPRT locus in FL, FL-M and FL-REV3^- cells

Cell line	MNNG (0.3 µM)	Antisense block of REV3	No. of mutants per 106 cells selected	Mutation frequency (10-6)
FL	0	None	2.87	2.87
	0.3		19.25bc	8.66
FL-M	0	None	4.00	4
	0.3		18.75 bc	18.75
FL-REV3-	0	Yes	0a	0
	0.3		7a	0.14

^a: mutants screened from 5 × 10⁷ cells;

^bP < 0.01 compared with spontaneous mutants in FL cell and FL-M cell;

^cP < 0.01 compared with FL-REV3^- cells.

Table 2 Mutation frequency of SupF tRNA gene in intact plasmid pZ189 after replicated in cultured human cells

Cell line	DMSO			MNNG
	Number of transformant	Number of mutant	Mutation frequency(10-4)	Number of transformant	Number of mutant	Mutation frequency(10-4)
293	7954	1	1.26	12205	9	7.37ab
293-M	15358	2	1.3	12040	7	5.81ab
293-REV3-	39236	9	2.29	19758	3	1.52
FL	13495	7	5.2	13854	38	27.4cd
FL-M	13272	7	5.3	10310	28	27.2cd
FL-REV3-	10967	3	2.7	12609	5	4

^{a, c}χ test P < 0.05 and 0.01 respectively as compared with spontaneous mutation frequency; ^{b, d}χ test P < 0.05 and 0.01 as compared with induced mutation frequency in 293-REV3^- and FL-REV3^- cells respectively.