| [Background]Colorectal cancer(CRC)is one of the most common malignant tumors in humans.In 2020,the most recent year for which data are available,colorectal cancer(10.0%)ranked third behind breast and lung cancer for both sexes.Cancer was the second leading cause of death(9.4 per cent)after lung cancer.The pathogenesis of colorectal cancer has not been completely clear,the current study shows that its pathogenesis is related to genetic factors,environmental factors,dietary habits,intestinal inflammation.Current studies suggest that the formation of colorectal cancer follows a multi-step and multi-stage evolution process from normal mucosa-colorectal adenoma-carcinoma,and about 80%of colorectal cancer is derived from colorectal adenoma.Studies have confirmed that the bowel gases emitted by healthy people are mainly hydrogen,oxygen,carbon dioxide,hydrogen,methane and a small amount of hydrogen sulfide.Bowel gas is associated with many intestinal diseases,such as non-specific diarrhea after vagal nerve resection and cholecystectomy,Crohn’s disease,ulcerative colitis,colon cancer,liver disease,etc.,but the specific mechanism is still unclear and deserves further confirmation.Gas signaling molecules carbon monoxide(CO)and CO-releasing molecules(CORMs)have the effects of scavenging free radicals,reducing inflammatory cell infiltration,anti-oxidation and anti-apoptosis,etc.Carbon monoxide is have important effect on development of tumor,but its effect and its mechanism is still not very clear,some research showed that carbon monoxide may inhibit restructuring,proliferation,migration of the epithelial cells,and achieve the effect of inhibiting tumor growth,but also has the opposite results.What had been proved was that CO synthetase(HO-1)can promote tumor by a variety of mechanisms.Hydrogen sulfide(H2S),as the third gas signaling molecule,has been found to promote the development of colorectal cancer in the low concentration range and inhibit the development of cancer in the high concentration range.In addition,the content of hydrogen sulfide and the expression of hydrogen sulfide synthase(CBS)in colon cancer tissue are both higher.Studies have also found that the concentration of CH4 and H2 exhaled by patients with high morbidity is higher than that of those with low morbidity.Patients with colorectal cancer also have a good intestinal environment for producing CH4,including anaerobic environment and increased bacteria producing CH4.As a substrate of CH4 synthesis,hydrogen has been proved to inhibit the growth of primary colorectal adenocarcinoma cells.Our study is to test positive rate and concentration difference of bowel gas carbon monoxide(CO),hydrogen sulfide(H2S),combustible gas(CH4 and H2)in colorectal cancer,intestinal polyps and normal control groups,and further testing CO synthetase(HO-1),H2S synthetase(CBS)expression differences between the groups.Preliminarylg exploring the mechanism of CO/HO-1,H2S/CBS in the development of colorectal cancer and evaluating the clinical significance of intestinal gases CO,H2S,combustible gases(CH4,H2),providing a new theoretical basis for the diagnosis and treatment of colorectal cancer.[Methods](1)Bowel gas was collected from 31 colorectal cancer patients,65 intestinal polyp(38 low-risk polyp,27 high-risk adenoma)and 31 normal population,including 70men and 57women,with an average of 57.94±10.30(31～77)years old.(2)To test positive rate and concentration difference of each study object by bowel gas analysis detector.(3)Intestinal tissues of some subjects in each group were randomly collected for immunohistochemical detection of HO-1 and CBS expression;(4)Questionnaires were designed to investigate and evaluate the general clinical data of the subjects.Then to further explore the relationship between bowel gas and colorectal cancer by the expression of intestinal gas synthase HO-1 and CBS.Finally,positive rate and concentration difference of bowel gas CO,H2S,combustible gases among each group was analyzed and evaluating its clinical significance.[Results](1)The overall positive rate of CO was 40.94%(52/127),which was 58.06%of colorectal cancer,22.22%of high-risk adenoma,36.84%of low-risk polyp and 45.16%of normal control group,respectively.There were significant differences in the positive rate between groups(P<0.05),and significant differences in the content of CO among groups(P<0.05).When each two groups were compared eparatedly,there were significant difference between the colorectal cancer group and the high-risk adenoma group(P<0.05),but no significant difference between the other group.(2)The overall positive rate of H2S was 12.60%(16/127),which was 35.48%of colorectal cancer,7.41%of high-risk adenoma,2.63%of low-risk polyp and 6.45%of normal control group,respectively.There were significant differences in the positive rate between groups(P<0.001),and significant differences in the content of H2S between groups(P<0.05).When each two groups were compared eparatedly,there were significant difference between the colorectal cancer group and the low-risk polyp group、normal control group(P<0.05),but no significant difference between the colorectal cancer group and the high-risk adenoma group(P>0.05).(3)The overall positive rate of combustible gases(CH4,H2)was 24.41%(31/127),which were 45.16%of colorectal cancer,11.11%of high-risk adenoma,18.42%of low-risk polyp and 22.58%of normal control group,respectively.There was significant difference in the positive rate between groups(P<0.05),and significant difference in the content between groups(P<0.05).When each two groups were compared eparatedly,there were significant difference between the colorectal cancer group and the high-risk adenoma group(P<0.05),but no significant difference between the other group.(4)Intestinal CO synthase(HO-1)and hydrogen sulfide synthase(CBS)were expressed in all groups,but the area percentage and intensity of expression were different(P<0.05).(5)There were significant differences in positive rate of bowel gas with personality type,education background and tumor marker(CEA and CA724),but no significant differences in positive rate of bowel gas with gender,age,height,weight;(6)The positive rate and content of CO in normal subjects,polyps,adenomas and colorectal cancer groups showed u-shaped changes,and the average content of synthase HO-1 expression in intestinal tract also showed inverted U-shaped changes.The positive rate of H2S in colorectal cancer group was significantly higher than that in the other three groups(P<0.001),but the average content of synthase CBS expression area in colorectal cancer group also showed inverted u-shaped change.[Conclusion](1)The positive rate of intestinal gases CO,H2S,and combustible gases(CH4,H2)in colorectal cancer patients were higher than those in other groups,and the expressions of CO synthase(HO-1)and H2S synthase(CBS)in intestinal tissues were increased gradually with the severity of the disease but decreased in the colorectal cancer group.The bowel gases CO/HO-1 and H2S/CBS were related to the occurrence and development of colorectal cancer,but the specific mechanism needed to be further explorated;(2)There are differences in bowel gas CO and combustible gas(CH4 and H2)between colorectal cancer group and high-risk adenoma group,which is conducive to the differentiation between high-risk adenoma and colorectal cancer.The positive rate and content of bowel hydrogen sulfide in colorectal cancer group are significantly higher than other groups,which is of great value for the early screening of colorectal cancer. |
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