CpG island methylator phenotype and Helicobacter pylori infection associated with gastric cancer

Table 1 Primer sets for nested methylation-specific polymerase chain reaction

Gene			Primer sequence (5'→3')
APC	U	F	GTGTTTTATTGTGGAGTGTGGGTT
		R	CCAATCAACAAACTCCCAACAA
	M	F	TATTGCGGAGTGCGGGTC
		R	TCGACGAACTCCCGACGA
WIF-1	U	F	GGGTGTTTTATTGGGTGTATTGT
		R	AAAAAAACTAACACAAACAAAATACAAAC
	M	F	CGTTTTATTGGGCGTATCGT
		R	ACTAACGCGAACGAAATACGA
RUNX-3	U	F	TTATGAGGGGTGGTTGTATGTGGG
		R	AAAACAACCAACACAAACACCTCC
	M	F	TTACGAGGGGCGGTCGTACGCGGG
		R	AAAACGACCGACGCGAACGCCTCC
DLC-1	U	F	AAACCCAACAAAAAAACCCAACTAACA
		R	TTTTTTAAAGATTGAAATGAGGGAGTG
	M	F	CCCAACGAAAAAACCCGACTAACG
		R	TTTAAAGATCGAAACGAGCGAGCG
SFRP-1	U	F	GAGTTAGTGTTGTGTGTTTGTTGTTTTGT
		R	CCCAACATTACCCAACTCCACAACCA
	M	F	GTGTCGCGCGTTCGTCGTTTCGC
		R	AACGTTACCCGACTCCGCGACCG
DKK	U	F	TTAGGGGTGGGTGGTGGGGT
		R	CTACATCTCCACTCTACACCCA
	M	F	GGGGCGGGCGGCGGGGC
		R	ACATCTCCGCTCTACGCCCG
E-cad	U	F	TAATTTTAGGTTAGAGGGTTATTGT
		R	CCACCCCAATACTAAATCACAACA
	M	F	TTAGGTTAGAGGGTTATCGCGT
		R	TAACTAAAAATTCACCTACCGAC

M: Methylated sequence; U: Unmethylated sequence; F: Forward sequence; R: Reverse sequence.

Table 2 Number of samples with methylated genes for gastric cancer, adjacent non-neoplastic tissue, and serum from gastric cancer patients and healthy controls

Gene	Tumor tissue	Serum from GC patients	Non-neoplastic tissues	Serum from healthy controls	χ2
	(n = 75)	(n = 75)	(n = 72)	(n = 40)
APC	36a	23	3	0	36.21
WIF- 1	43a	26	4	0	45.28
DLC-1	38a	22	3	0	39.49
DKK	41a	24	2	0	47.79
SFRP-1	39a	25	4	0	38.29
E-cad-1	36a	20	3	0	36.21
RUNX-3	42a	28	5	0	40.64

^aP < 0.05 vs the number of methylated gene promoters for tumor and non-neoplastic tissue samples with the χ² test. GC: Gastric cancer.

Table 3 CpG island methylator phenotype associated with Helicobacter pylori infection in 75 gastric cancer tissue and serum samples

CIMP	H. pylori infection in tissue samples		H. pylori infection in serum samples
	Negative (-)	Positive (+)	Negative (-)	Positive (+)
Negative (-)	13	15	14	17
Positive (+)	11	36a	10	34a

^aP < 0.05 vs the frequencies of CIMP between H. pylori+ and H. pylori- samples in serum with the χ² test. H. pylori: Helicobacter pylori; CIMP: CpG island methylator phenotype.

Table 4 Prognosis of CpG island methylator phenotype cases associated with Helicobacter pylori infection in gastric cancer

Prognosis	H. pylori+		H. pylori-		χ2
	CIMP+	CIMP-	CIMP+	CIMP-
Metastasis
Yes	9	2	2	1	3.593a
No	22	15	8	13
Recurrence
Yes	10	3	2	2	2.369a
No	21	14	8	12
Survival
Yes	24	15	8	12	1.043
No	7	2	2	2

^aP < 0.05 vs the prognosis between H. pylori+/CIMP+ and H. pylori+/CIMP- in serum with the χ² test. H. pylori: Helicobacter pylori; CIMP: CpG island methylator phenotype.