Global hypomethylation in hepatocellular carcinoma and its relationship to aflatoxin B1 exposure

Table 1 Methylation levels of hepatocellular carcinoma tumor and adjacent non-tumor liver tissue

	Tumor	Adjacent	P value
	mean ± SD	mean ± SD
LINE1 (%)	48.6 (14.8)	71.7 (1.4)	< 0.0001
Sat2 (%)	42.2 (55.1)	117.9 (88.8)	< 0.0001
Methyl acceptance (DPM/ng)	70.0 (54.8)	32.4 (15.6)	0.040

LINE1: Long interspersed nucleotide element-1; Sat2: Satellite 2; DPM: Disintegrations/min.

Table 2 Correlations between methylation levels and aflatoxin B₁- albumin adducts in hepatocellular carcinoma tumor tissues

	AFB1-Alb	P value
	r
LINE1 (%)	-0.36	0.034
Sat2 (%)	-0.30	0.082
Methylacceptance DPM/ng)	0.18	0.286

AFB1: Aflatoxin B₁; LINE1: Long interspersed nucleotide element-1; Sat2: Satellite 2; DPM: Disintegrations/min.

Table 3 Methylation levels in tumor tissues and clinical characteristic and gene-specific methylation in tumor tissues

Variable	n	LINE1 (%)	P value	Sat2 (%)	P value	Methyl acceptance (DPM/ng)	P value
		mean ± SD		mean ± SD		mean ± SD
HBsAg
Negative	5	41.0 (16.6)	0.245	22.1 (19.2)	0.905	67.2 (37.6)	0.607
Positive	26	47.7 (13.6)		31.3 (34.5)		81.3 (58.3)
AntiHCV
Negative	18	49.6 (14.2)	0.449	27.6 (22.6)	0.737	72.1 (49.7)	0.759
Positive	10	45.2 (14.3)		38.0 (47.7)		86.5 (71.3)
HBsAg and AntiHCV
Both negative	1	24.9	0.047	5.7	0.323	64.5	0.877
Either one positive	31	47.2 (13.5)		31.1 (32.2)		78.4 (55.5)
Cirrhosis
No	17	44.8 (15.2)	0.388	28.1 (23.8)	0.791	78.6 (52.4)	0.927
Yes	13	48.9 (13.2)		32.5 (43.1)		82.3 (61.9)
p16Ink4A
Unmethylated	15	50.9 (16.7)	0.569	63.4 (80.8)	0.437	62.0 (61.2)	0.155
Methylated	22	47.1 (13.5)		27.8 (21.1)		75.4 (50.8)
Hint1
Unmethylated	17	50.9 (14.8)	0.405	51.8 (75.8)	0.951	60.2 (48.9)	0.142
Methylated	20	46.7 (14.8)		34.1 (30.3)		78.3 (59.4)

HCV: hepatitis V virus; LINE1: Long interspersed nucleotide element-1; Sat2: Satellite 2; DPM: Disintegrations/min.