The Relationship Of Leptin With Cell Apoptosis Of Colorectal Adenocarcinoma And Nuclear Factor-kappa B, Phosphoinositide-3 Kinase Signal Conducting Pathways

ObjectivesThrough detecting the expression of Leptin, Nuclear Factor-kappaB(NF-κB)(p65), Phosphoinositide-3Kinase (PI-3K) and Caspase-3 (akind of protein symbolling cell apoptosis) in colorectal adenocarcinoma,adenoma of colon and normal colonic epithelial cells, aimed toapproach the function of Leptin during the carcinogenesis process ofcolorectal carcinoma, its relationship with cell apoptosis and toinvestigate if the function of Leptin interferes with NuclearFactor-kappaB(NF-κB) or Phosphoinositide-3Kinase (PI-3K) signalconducting pathways. This study was aimed to explore the cancero-genesis mechanism of the colorectal adenocarcinoma penetratingly; tolook for new gene therapy ways for the colorectal adenocarcinomaclinical treatment and to provide with related theoretical bases.MethodsImmunohistochemistry streptavidin-peroxidase method wasperformed in detecting the expression of the four proteins above incolorectal carcinoma, adenoma of colon and normal colonic epithelialcells. To analyze their relationship and to compared their positiveexpression rates with clinicopathological parameters.Results1. The expression level of Leptin in colorectal adenocarcinoma washigher than adenoma of colon; which in well-and moderatelydifferentiated colorectal adenocarcinoma was higher than normalcolonic epithelial tissue and both of which were higher than poorlydifferentiated colorectal adenocarcinoma, the differences were allsignificant(p all＜0.01).There was no significance between theexpression level of Leptin in colorectal adenocarcinoma located inleft hemicolon and in right hemicoton(Colon was divided into lefthemicolon and right hemicolon by transverse colon: the former included splenic flexure of colon, descending colon, sigmoid colonand rectum; the latter included blind gut, ascending colon andhepatic flexure of colon), and the expression level of Leptin had nosignificant relationship with the infiltrating depth of carcinoma cellsor lymphoid node metastasis(p all＞0.05).2. The expression level of Nuclear Factor-kappa B(NF-κB) in colorectaladenocarcinoma and in normal colon team were higher than colonadenoma; which in well-and moderately differentiated colorectaladenocarcinoma was higher than normal colon team and both ofwhich were higher than poorly differentiated colorectaladenocarcinoma, the differences were all significant(p all＜0.05). Theexpression level of Nuclear Factor-kappa B(NF-κB) had no signi-ficant relationship with the location of colorectal carcinoma(left orright hemicolon),the infiltrating depth of carcinoma cells orlymphoid node metastasis(p all＞0.05).3. The expression level of Phosphoinositide-3Kinase (PI-3K) in normalcolonic epithelial tissue, adenoma of colon and colorectaladenocarcinoma down regulated by turns, which in well-andmoderately differentiated colorectal adenocarcinoma was higher thanpoorly differentiated colorectal adenocarcinoma (p＜0.01). Thepositive rate of PI-3K correlated with the infiltrating depth ofcarcinoma cells, which infiltrating over serous membrane was higherthan which infiltrating until serous membrane, the difference hadsignificance(p=0.048).While the expression level of PI-3K had nosignificant relationship with the location of colorectal carcinoma(leftor right hemicolon) or lymphoid node metastasis(p all＞0.05).4. The expression level of Caspase-3 in normal colonic epithelial cellswas higher than which in colon adenoma and colorectaladenocarcinoma cells. Which in well-and moderately differentiatedcolorectal adenocarcinoma was higher than poorly differentiated colorectal adenocarcinom, the differences had significance (pall＜0.05). There was no significance between the expression level ofCaspase-3 in adenoma of colon and in colorectal carcinoma,meanwhile the expression positive rate of Caspase-3 had nosignificant relationship with the location of colorectal carcinoma(leftor right hemicolon),the infiltrating depth of carcinoma cells orlymphoid node metastasis(p all＞0.05).5. In all the data, the expression of Leptin and Caspase-3 expressed anopposite trend, but there was no statistical relationship betweenthem(p＞0.05);there was manifest positive correlation between theexpression level of Leptin and Nuclear Factor-kappa B(NF-κB)(r=0.643,p=0.000); while another positive correlation existedbetween the expression level of Leptin and Phosphoinositide-3Kinase(PI-3K) (r=0.443,p=0.000);.While in the colorectal adenocarcinomatissue, none of the expression level of Leptin, Factor-kappa B(NF-κB) or Phosphoinositide-3Kinase (PI-3K) had any statisticalrelationship with the expression level of Caspase-3(p all＞0.05);meanwhile, both of the relationships between Leptin andFactor-kappa B(NF-κB), Leptin and Phosphoinositide-3Kinase(PI-3K) were all positive(p=0.000).Conclusion1. The expression levels of Caspase-3, the cell apoptosis effectingprotein, in adenoma of colon and colorectal adenocarcinoma werelower than in normal colon team. This result implied that theexpression level of Caspase-3 down regulated in the precancerousstage of colorectal carcinoma, its down regulation might be an earlierperiod event during the carcinogenesis process of colorectaladenocarcinoma so we suppose Caspase-3 could be a detecting indexduring this earlier period; which also demonstrated that cellapoptosis happened in adenoma of colon and colorectal adenocarcinoma was less than that in normal colonic epithelial cells.The decrease or inhibition of cell apoptosis promoted the formationof colorectal adenoma and colorectal carcinoma.2. NF-κB(p65) as one of apoptosis inhibitors participated in theformation of colorectal adenocarcinoma(especially well-andmoderately differentiated colorectal adenocarcinoma) and thecanceration process of colorectal adenoma into colorectal carcinoma.3. PI-3K was one of apoptosis inhibitors in colorectal adenocarcinomacells; testing the expression of PI-3K in colorectal adenocarcinomamight have some reference use in predicting patients' prognosis.4. Leptin participated in the carcinogenesis process of colorectaladenocarcinoma(especially well-and moderately differentiatedcolorectal adenocarcinoma) and also reacted in the process ofcolorectal adenoma transforming into colorectal carcinoma, the upregulation of the Leptin's expression level promoted the formation ofcolorectal carcinoma. The expression level of Leptin had nosignificant relationship with the infiltrating depth of carcinoma cellsor lymphoid node metastasis. So it seems that Leptin didn'tparticipate in the progression of colorectal carcinoma.5. Leptin reacted as an apoptosis inhibiting factor in the formation ofcolorectal carcinoma(especially well-and moderately differentiatedcolorectal adenocarcinoma); the apoptosis inhibiting function ofLeptin reacted through NF-κB and PI-3K pathways, and this functionwas more closer with NF-κB signal transducting pathway.6. The expression level of Leptin, NF-κB(p65) and PI-3K in well-andmoderately differentiated colorectal adenocarcinoma was all higherthan that in poorly differentiated colorectal adenocarcinoma, thisresult indicated that all these three proteins might have somerelationship with the biological behavior of colorectaladenocarcinoma. 7.In conclusion, this study manifested that Leptin could be one of theexperimental detecting indexes in colorectal adenocarcinoma clinicaldiagnosis. It also provided with theoretical bases for taking Leptinrivalry as one of adjunctive therapies in clinical treatment ofcolorectal carcinoma.