AIM:To investigate angiopoietin(Ang) and vascular endothelial growth factor(VEGF) expression in rats with ulcerative colitis(UC) and colorectal cancer(CRC).METHODS:Dysplasia and cancer were investigatedin rats that received three cycles of 3.5% dextran sulfate sodium(DSS) in drinking water for 7 d followed by distilled water for 14 d after intraperitoneal pretreatment with 20 mg/kg 1,2-dimethylhydrazine(DMH)(CRC group).Colitis was investigated in rats that received three cycles of 3.5% DSS in drinking water for 7 d followed by distilled water for 14 d after intraperitoneal pretreatment with saline(UC group).Rats without DSS or DMH treatment served as controls.Expression of the tyrosine kinase with immunoglobulinlike and EGF-like domains(Tie)-2 and its ligands,Ang-1 and Ang-2,as well as VEGF were evaluated in the colorectum by Western blotting.RESULTS:Compared with rats in the control group,rats in the CRC and UC groups developed the symptoms of acute colitis with diarrhea,rectal bleeding,wasting,and loss of body weight(P < 0.05).In addition,the mean length of colorectum of CRC and UC rats was significantly shorter than that of control rats(8.29 ± 0.21 and 8.31 ± 0.86,respectively,vs 12.34 ± 0.12 cm; P < 0.05).Furthermore,rats in the CRC group,but not in the UC or control groups,developed multiple tumors in the colorectal region.Western blot analysis revealed that rats in the CRC and UC groups had markedly increased protein levels of Ang-1,Ang-2,Tie-2,and VEGF in the colorectum compared to rats in the control group.CONCLUSION:Increased expression of Ang-1,Ang-2,Tie-2,and VEGF in ulcerative colitis-derived colorectal cancer might lead to chronic colitis and pathologic angiogenesis in rats. AIM: To investigate angiopoietin (Ang) and vascular endothelial growth factor (VEGF) expression in rats with ulcerative colitis (UC) and colorectal cancer (CRC). METHODS: Dysplasia and cancer were investigated in rats that received three cycles of 3.5% dextran sulfate sodium (DSS) in drinking water for 7 d followed by distilled water for 14 d after intraperitoneal pretreatment with 20 mg / kg 1,2-dimethylhydrazine (DMH) (CRC group). Colitis was investigated in rats that received three cycles of 3.5% DSS in drinking water for 7 d followed by distilled water for 14 days after intraperitoneal pretreatment with saline (UC group). Rats without DSS or DMH treatment served as controls. Expression of the tyrosine kinase with immunoglobulin like and EGF-like domains (Tie) -2 and its ligands, Ang-1 and Ang-2, as well as VEGF were evaluated in the colorectum by Western blotting .RESULTS: Compared with rats in the control group, rats in the CRC and UC groups developed the symptoms of acute colitis with diarrhea , rectal bleedi ng, wasting, and loss of body weight (P <0.05) .In addition, the mean length of colorectum of CRC and UC rats was significantly shorter than that of control rats (8.29 ± 0.21 and 8.31 ± 0.86, respectively, vs 12.34 ± 0.12 cm; P <0.05) .Furthermore, rats in the CRC group, but not in UC or control groups, developed multiple tumors in the colorectal region. Western blot analysis revealed that rats in the CRC and UC groups had markedly increased protein levels Ang-2, Tie-2, and VEGF in the colorectum compared to rats in the control group. CONCLUSION: Increased expression of Ang-1, Ang-2, Tie- 2, and VEGF in ulcerative colitis-derived colorectal cancer might lead to chronic colitis and pathologic angiogenesis in rats.