Relationship between indoleamine 2,3-dioxygenase activity and lymphatic invasion propensity of colorectal carcinoma

Table 1 Serum tryptophan, kynurenine and neopterin, urinary neopterin and biopterin of cancer-free group (Group 1) and colorectal cancer patients (Group 2)

Group	Group 1(n = 43)	Group 2(n = 44)	P value
Age (yr)1	62.06 ± 2.07	60.95 ± 2.11	0.708
Tryptophan (μmol/L)1	21.95 ± 1.03	19.91 ± 1.33	0.254
Kynurenine (μmol/L)2	1.03 ± 0.19	1.20 ± 0.13	0.042a
Kynurenine/tryptophan1	41.31 ± 3.62	89.47 ± 14.32	0.006a
Serum neopterin (nmol/L)2	13.28 ± 1.08	16.93 ± 2.84	0.634
Urinary neopterin (μmol neopterin/mol creatinine	63.54 ± 5.64	80.45 ± 8.09	0.090
Urinary biopterin (μmol biopterin/mol creatinine)1	67.33 ± 6.22	91.41 ± 12.00	0.038a
Urinary neopterin (μmol neopterin/mol creatinine) + urinary biopterin (μmol biopterin/mol creatinine)1	129.83 ± 9.42	172.60 ± 17.17	0.048a

^aP < 0.05, Group 2 vs Group 1 considered statistically significant;

¹Independent sample t-test;

²Mann-Whitney U test. Colorectal cancer patients showed more than two times increase in overall serum kynurenine-tryptophan ratio and a non-significant rise in the activity of pteridine pathway when compared with the cancer-free patients (Group 1).

Table 2 Evaluation of serum pteridine and tryptophan metabolites of lymphatic invasion negative (Group 2/c) and positive (Group 2/d) colorectal cancer patients

Group	Group 2/c(n = 21)	Group 2/d(n = 23)	P value
Tryptophan (μmol/L)1	19.14 ± 1.68	20.62 ± 2.06	0.586
Kynurenine (μmol/L)2	1.45 ± 0.24	0.96 ± 0.11	0.080
Kynurenine/tryptophan	95.85 ± 17.40	83.08 ± 23.13	0.662
Serum neopterin (nmol/L)2	18.43 ± 5.18	15.56 ± 2.78	0.613
Urinary neopterin (μmol neopterin/mol creatinine)1	85.79 ± 11.76	75.68 ± 11.34	0.541
Urinary biopterin (μmol biopterin/mol creatinine)1	76.56 ± 16.44	105.43 ± 17.20	0.234
Urinary neopterin (μmol neopterin/mol creatinine) + urinary biopterin (μmol biopterin/mol creatinine)1	167.42 ± 21.83	177.50 ± 26.82	0.774
IDO (%)	24.04 ± 6.90	44.56 ± 6.11	0.031a

^aP < 0.05, group 2/c vs group 2/d, considered statistically significant;

¹Independent sample t-test;

²Mann-Whitney U test. The comparison displayed that serum indoleamine-2,3-dioxygenase (IDO) activities were strongly predictive for lymphatic invasion.

Table 3 Evaluation of serum pteridine and tryptophan metabolites of lymph node metastasis negative (Group 2/a) and positive (Group 2/b) colorectal cancer patients

Group	Group 2/a(n = 32)	Group 2/b(n = 12)	P value
Tryptophan (μmol/L)1	18.04 ± 1.39	23.98 ± 2.98	0.047a
Kynurenine (μmol/L)1	1.33 ± 0.17	0.87 ± 0.14	0.139
Kynurenine/tryptophan1	103.20 ± 18.13	53.27 ± 17.36	0.121
Serum neopterin (nmol/L)2	17.78 ± 3.68	14.67 ± 3.94	0.368
Urinary neopterin (μmol neopterin/mol creatinine)1	83.07 ± 9.76	71.29 ± 12.96	0.552
Urinary biopterin (μmol biopterin/mol creatinine)1	96.87 ± 13.83	69.56 ± 23.13	0.371
Urinary neopterin (μmol neopterin/mol creatinine) + Urinary biopterin (μmol biopterin/mol creatinine)1	179.95 ± 20.48	143.23 ± 24.95	0.400
IDO (%)1	30.32 ± 5.74	48.75 ± 8.30	0.089

^aP < 0.05; group 2/a vs group 2/b, considered statistically significant;

¹Independent sample t-test;

²Mann-Whitney U test. The comparison displayed that serum indoleamine-2,3-dioxygenase (IDO) activities were not predictive for lymph node dissemination alone.

Table 4 Correlation between lymphatic invasion and lymph node metastasis, total serum indoleamine-2,3-dioxygenase score and serum tryptophan in colorectal cancer patients

	Pearson correlation
Lymphatic invasion	Lymph node metastasis	Tumor total IDO score
	P = 0.001a, r = +0.476	P = 0.014a, r = +0.366
Lymph node metastasis	Serum tryptophan	Tumor total IDO score
	P = 0.047a, r = +0.305	P = 0.043a, r = +0.310

^aP < 0.05 considered statistically significant. IDO: Indoleamine-2,3-dioxygenase.

Table 5 Evaluation of the association between lymphatic invasion, lymph node metastasis and tumor total indoleamine-2,3-dioxygenase score in colorectal cancer patients

Lymphocytic infiltration- lymphatic invasion	P = 0.211
Lymph node metastasis- lymphatic invasion	P = 0.002a
Tumor differentiation- lymphatic invasion	P = 0.358
Tumor total IDO score- lymphatic invasion	P = 0.016a

^aP < 0.05 considered statistically significant. Lymphatic invasion showed linear-by-linear association with lymph node metastasis and tumor total IDO score in colorectal cancer patients. IDO: Indoleamine-2,3-dioxygenase.