Mitochondrial uncoupling protein 2 expression in colon cancer and its clinical significance

Table 1 Clinical and histological features of colon cancer patients

Characteristics	n (%)
Gender
Female	33 (42.3)
Male	45 (57.7)
Age (yr): median 60.7, range 31-78
< 60	36 (46.2)
≥ 60	42 (53.8)
Primary sites
Left colon	44 (56.4)
Right colon	34 (43.6)
Clinical stage
I(T1N0M0)	10
II (T2N0M0)	17
III	37
IV	14
Tumor differentiation
Well	16
Moderately	38
Poorly	24

Table 2 Uncoupling protein 2 mRNA expression in human colon cancer and peritumoral tissue samples detected by quantitative real-time polymerase chain reaction

Patient No.	Tissue	UCP2 mRNA relative abundance	T/P
1	T	8.12	3.45
	P	2.35
2	T	19.68	5.70
	P	3.45
3	T	13.6	2.96
	P	4.6
4	T	21.4	2.32
	P	9.21
5	T	26.2	3.67
	P	12.7
6	T	78.6	2.51
	P	31.2
7	T	86.5	3.59
	P	24.1
8	T	12.31	6.00
	P	20.5
9	T	45.2	8.85
	P	5.1
10	T	36.1	0.84
	P	42.6
11	T	9.12	2.37
	P	3.85
12	T	3.67	1.78
	P	2.05
13	T	10.34	4.40
	P	2.35
14	T	17.63	5.86
	P	3.01
15	T	6.54	4.47
	P	1.46
Average T/P ratio			3.92

UCP2: Uncoupling protein 2; T: Tumour; P: Peritumoral.

Table 3 Uncoupling protein 2 protein expression in human colon cancer and peritumoral tissue samples detected by Western blotting

Patient No.	Tissue	UCP2 protein (total gray)	T/P
1	T	2.10	2.14
	P	0.98
2	T	4.16	5.33
	P	0.78
3	T	2.45	2.82
	P	0.87
4	T	5.14	4.25
	P	1.21
5	T	3.02	3.70
	P	0.82
6	T	6.24	2.70
	P	2.31
7	T	5.55	5.00
	P	1.09
8	T	8.27	3.93
	P	2.1
9	T	9.43	8.65
	P	1.08
10	T	1.96	0.78
	P	2.51
11	T	3.15	3.80
	P	0.83
12	T	7.12	2.13
	P	3.34
13	T	4.51	3.72
	P	1.21
14	T	7.12	5.45
	P	1.31
15	T	2.54	4.17
	P	0.62
Average T/P			3.27

UCP2: Uncoupling protein 2; T: Tumour; P: Peritumoral.

Table 4 Uncoupling protein 2 expression in different diseases detected by immunohistochemistry

Tissue	n	Negative	Mild	Moderate	Strong	Rate of positive (%)
Normal colon	10	10	0	0	0	0
Hyperplastic polyps	10	9	2	0	0	20
adenoma	20	9	3	6	2	55
Colon cancer	78	10	15	30	22	85.9

Positive cells < 15% in negative control and ≥ 15% positive cells were counted as positive. Staining intensity was classified as negative (0), mildly positive (+1), moderately positive (+2), and strongly positive (+3).

Table 5 Relation between uncoupling protein 2 expression and clinical pathological features of colon cancer

Tumor differentiation/clinical stage	Positive staining rate of UCP2 (%)	P
Tumor differentiation
Well differentiation	72.8	0.072
Poor differentiation	91.4
Clinical stage
Stage I + II	65.1	0.0321, 0.02482
Stage III	80.4	0.2483
Stage IV	92.6

¹P = 0.032, uncoupling protein 2 (UCP2) expression in colon tissue from patients with clinical stage III vs that in colon tissue from patients with clinical stage I + II;

²P = 0.0248, UCP2 expression in colon tissue from patients with clinical stage IV vs that in colon tissue from patients with clinical stage I + II;

³P = 0.248, UCP2 expression in patients with clinical stage IV vs that in colon tissue from patients with stage III.

Table 6 Univariate Cox proportional hazards analysis of metastasis variables in colon cancer patients

Variable	Hazard ratio	95% CI	P-value
Age (≥ 60 yr)	0.098	0.081-33.058	0.915
Gender	0.895	0.078-41.221	0.389
Primary site	2.135	0.610-18.281	0.078
Tumor differentiation	1.270	0.031-1.672	0.049
UCP2 high expression	4.321	0.035-0.682	0.046

UCP2: Uncoupling protein 2; CI: Confidence interval.