AIM:To evaluate the effect of reactive oxygen species suchas hydrogen peroxide on the progression of human coloncancer.METHODS:Human colon carcinoma cell lines,LS174T andHCT8,were treated respectively with 10~(-5),10~(-7)or 10~(-9)mol·L~(-1)hydrogen peroxide for 24h,and co-cultured with humanendothelial cell line ECV-304.The migration of ECV-304induced by cancer cells was calculated and the expressionlevel of vascular endothelial growth factor in cancer cellswas determined by RT-PCR analysis and ELISA.Dactinomycin of 1.5mg·L~(-1)which could block transcriptionof cancer cells was applied to observe the effects of H_2O_2 ontranscriptional activity and the relative half-life of VEGFmRNA.Finally,to evaluate the effect H_2O_2 on NF-κB activityin colon cancer cells,NF-κB in cytoplasm and nucleus of thecells were detected with FITC-tagged antibody and itspresence in the nucleus(Fn)vs cytoplasm(Fc)wasmonitored by measuring the green fluorescence integratedover the nucleus by laser scanning cytometry(LSC).RESULTS:Exogenouse hydrogen peroxide of lowconcentration increased the migration of endothelial cellsinduced by colon cancer cells.When cancer cells weretreated with 10~(-5)mol·L~(-1)H_2O_2,the migration number ofendothelial cells induced by LS174T ceils was 203±70,andthe number induced by HCT8 cells was 145±65.The twovalues were significantly higher than those treated with otherconcentrations of H_O_2(P<0.01).The expression ofvascular endothelial growth factor in cancer cells,whichcould be blocked by dactinomycin,were increased to acertain degree,while the relative half-life of VEGF mRNAwas not prolonged after treatment with hydrogen peroxide.The activity of NF-κB in colon cells rose after the cells wereexposed to hydrogen peroxide for 24h.The Fn values inHCT8 cells were 91±13(0 mol·L~(-1)H_2O_2)and 149±40(10~(-5)mol·L~(-1)H_2O_2)(P<0.05),in LS174T cells were 127±35(0mol·L~(-1)H_2O_2)and 192±11(10~(-5)mol·L~(-1)H_2O_2)(P<0.05).It is similar to the case of VEGF expression in cancer cells.CONCLUSION:Hydrogen peroxide increases vascularendothelial growth factor expression in colon cancer cells,and it is likely that reactive oxygen species such ashydrogen peroxide facilitates the development of coloncancer. AIM: To evaluate the effect of reactive oxygen species suchas hydrogen peroxide on the progression of human colon cancer. METHODS: Human colon carcinoma cell lines, LS174T and HCT8, were treated respectively with 10 ~ (-5), 10 ~ (-7) or 10 ~ (-9) mol·L -1 hydrogen peroxide for 24h, and co-cultured with humanendothelial cell line ECV-304. The migration of ECV-304 induced by cancer cells was calculated and the expression level of vascular endothelial growth factor in cancer cells was determined by RT-PCR analysis and ELISA. Actinomycin of 1.5 mg · L -1 which could block transcription of cancer cells was applied to observe the effects of H 2 O 2 on transcription activity and the relative half-life of VEGF mRNA. Finaally, to evaluate the effect of H_2O_2 on NF-κB activity in colon cancer cells, NF-κB in cytoplasm and nucleus of the cells were detected with FITC-tagged antibody and its presence in the nucleus (Fn) vs cytoplasm (Fc) wasmonitored by measuring the green fluorescence integratedover the nucleus by laser scanning cytometry (LSC) .RESULTS: Exogenouse hydrogen peroxide of low concentration increased the migration of endothelial cells induced by colon cancer cells .When cancer cells were treated with 10 ~ (-5) mol·L -1 H_2O_2, the migration number of endothelial cells induced by LS174T ceils was 203 ± 70, and the number induced by HCT8 cells was 145 ± 65.The two values ​​were significantly higher than those treated with otherconcentrations of H_O_2 (P <0.01). The expression ofvascular endothelial growth factor in cancer cells, whichcould be blocked by dactinomycin, were increased to acertain degree, while the relative half-life of VEGF mRNA was not prolonged after treatment with hydrogen peroxide. The activity of NF-κB in colon cells rose after the cells wereexposed to hydrogen peroxide for 24h. The Fn values ​​in HCT8 cells were 91 ± 13 (0 mol·L -1 H 2 O 2) and 149 ± 40 (10 -5 mol·L -1 H 2 O 2) (P <0.05) 35 (0 mol·L -1 H 2 O 2) and 192 ± 11 (10 -5 mol·L -1 H 2 O 2) (P <0.05) .It is similar to the case of V EGF expressionin cancer cells. CONCLUSION: Hydrogen Peroxide increases vascularendothelial growth factor expression in colon cancer cells, and it is likely that reactive oxygen species such as hydrogen peroxide facilitates the development of coloncancer.