Chemoprevention of tea on colorectal cancer induced by dimethylhydrazine in Wistar rats

Table 1 Body weights during the study (x^-± s)

Treatment groups	Week 0	Week 16	Week 32
DMH	70.14 ± 5.92	425.69 ± 44.06	456.25 ± 94.36
Green tea + DMH	69.73 ± 6.25	427.60 ± 44.11	459.19 ± 95.52
Tea pigments + DMH	70.23 ± 5.35	425.39 ± 46.99	463.24 ± 98.50
Negative control	69.62 ± 6.20	430.89 ± 47.36	487.31 ± 99.58

DMH: Dimethylhydrazine; EDTA: Ethylene diamine tetracetate acid.

Table 2 Effect of tea on DMH-induced ACF (x^-± s)

Treatment groups	Total	Small	Medium	Large
DMH	249.88 ± 10.891	61.50 ± 8.07	63.75 ± 1.85	24.62 ± 2.87
Green tea + DMH	148.25 ± 14.05a	91.75 ± 12.63a	44.10 ± 1.80a	12.50 ± 1.58a
Tea pigments + DMH	204.25 ± 11.94a	126.50 ± 10.37a	53.00 ± 2.24a	17.38 ± 3.04a
Negative control	0	0	0	0

ACF: Aberrant crypts foci.

^aP < 0.01, comparison with DMH group by Student’s t test.

Table 3 Effect of tea on DMH-induced colon tumors

Treatment groups	na	nb	Average number of tumors per rat	Mean tumor volume
DMH	20	20	2.55 ± 1.36	294.69 ± 614.43
Green tea + DMH	20	14	1.35 ± 1.27c	66.87 ± 58.20d
Tea pigments + DMH	20	16	1.45 ± 1.16c	94.83 ± 120.89d
Negative control	20	0	0	0

^aNo. of animals; ^bNo. of animals with tumors;

^cP < 0.01, comparison with DMH group by Student’s t test.

^dP < 0.01, comparison with DMH group by Wilcoxon test.

Table 4 Effect of tea on PCNA-LI in colonic mucosa of DMH-treated rats (x^-± s)

Treatment groups	PCNA-LI
	Week 16 (n = 8)	Week 32 (n = 8)
DMH	41.75 ± 6.01	52.53 ± 5.40
Green tea + DMH	22.02 ± 3.63a	36.63 ± 5.41a
Tea pigments + DMH	29.66 ± 2.65a	40.36 ± 5.64a
Negative control	14.34 ± 4.68	15.43 ± 5.08

PCNA: Proliferating cell nuclear antigen.

^aP < 0.01, comparison with DMH group by Student’s t test.

Table 5 Effect of tea on expression levels of ras-p21(x^-± s)

Treatment groups	ras-p21 expression
	Week 16 (n = 8)	Week 32 (n = 8)	Week 32 (n = 8)
	colonic mucosa	colonic mucosa	colon tumors
DMH	2.03 ± 0.35	2.26 ± 0.28	3.16 ± 0.32
Green tea + DMH	1.36 ± 0.14a	1.48 ± 0.12a	2.07 ± 0.15a
Tea pigments + DMH	1.51 ± 0.19a	1.72 ± 0.15a	2.36 ± 0.16a
Negative control	1	1	1

^aP < 0.01, comparison with DMH group by Student’s t test.

Table 6 Effect of tea on Bcl-2 expression

Treatment groups	Week 16 (n = 8)				Week 32 (n = 8)
	I	II	III	IVa	I	II	III	IV
DMH	1	1	3	3	0	1	2	5
Green tea + DMH	2	5	1	0b	2	5	1	0c
Tea pigments + DMH	1	5	1	1b	2	4	2	0c
Negative control	6	2	0	0	5	3	0	0

^aPositive cells were expressed as the percentage of the total number of cells, and classified into 4 categories: I, 0%-25%; II, 25%-50%; III, 50%-75%; and IV, 75%-100%.

^bP < 0.05,

^cP < 0.01, comparison with DMH group by Wilcoxon test.

Table 7 Effect of tea on Bax expression

Treatment groups	Week 16 (n = 8)				Week 32 (n = 8)
	I	II	III	IVa	I	II	III	IV
DMH	2	5	1	0	3	5	0	0
Green tea + DMH	0	1	5	2b	0	1	3	4c
Tea pigments + DMH	0	3	4	1b	0	1	4	3c
Negative control	6	2	0	0	5	3	0	0

^aPositive cells were expressed as the percentage of the total number of cells, and classified into 4 categories: I, 0%-25%; II, 25%-50%; III, 50%-75%; and IV, 75%-100%.

^bP < 0.05,

^cP < 0.01, comparison with DMH group by Wilcoxon test.