Impaired 8-Hydroxyguanine Repair Activity of MUTYH Variant p.Arg109Trp Found in a Japanese Patient with Early-Onset Colorectal Cancer

Table 4

supF mutations in a supF forward mutation assay using the pMY189 plasmid containing 8-hydroxyguanine (8OHG) at position 159 of supF in H1299 human cell lines inducibly expressing MUTYH protein.

Cell line^a	Plasmid^b	PCR and gel electrophoresis		Sequencing
		Number of mutant clones analyzed	Number of mutant clones showing the same mobility as a WT clone (%)	Number of mutant clones analyzed	Number of mutant clones containing a mutation at position 159 of supF (%)
					Total	G:C to T:A	G:C to A:T	G:C to C:G
Empty	G (WT)	22	3 (13.6)	3	0 (0)	0 (0)	0 (0)	0 (0)
Empty	8OHG	40	38 (95.0)^c	24	24 (100)	22 (91.7)^d	1 (4.2)	1 (4.2)
WT	8OHG	25	13 (52.0)^c	13	8 (61.5)	6 (46.2)^d	1 (7.7)	1 (7.7)
p.R81W	8OHG	40	37 (92.5)^c	24	23 (95.8)	22 (91.7)^d	0 (0)	1 (4.2)
p.D208N	8OHG	40	38 (95.0)^c	24	23 (95.8)	23 (95.8)^d	0 (0)	0 (0)

aEmpty vector-transposed H1299 human cancer cell line and H1299 cells inducibly expressing type 2 MUTYH protein of WT, p.Arg81Trp, or p.Asp208Asn were used.
^bThe shuttle plasmid pMY189, containing 8-hydroxyguanine (8OHG) at nucleotide position 159 of supF, or a wild-type (WT) pMY189 plasmid was used.
^cThe 𝑃 value for the difference in the proportion between cells transfected with an 8OHG-containing pMY189 plasmid was <0.0001 (Fisher exact test).
^dThe 𝑃 value for the difference in the proportion between cells transfected with an 8OHG-containing pMY189 plasmid was <0.001 (Fisher exact test).