The Study Of The Expression And Significance Of Insulin-like Growth Factor System In Colorectal Cancer

Background and ObjectiveThe incidence and fatality of colorectal cancer has been increasing rapidly recent 20 or 30 years. Colorectal cancer has been the third commonest cancer in word demonstrated by epidemiology data. Long-term survival of colorectal cancer is related to the stage of disease. If detected early, it may be curable by surgery. But once metastases develop the prognosis becomes poor. Therefore, early diagnosis and therapy is the key to improve the curative effect of colorectal cancer. The research of the contribution and mechanism between IGFs and colorectal cancer have been a hot spots.The IGF system includes ligands IGF-I and-Ⅱ, their receptors, IGF-binding proteins (IGFBPs) and IGF proteases, which regulate the proliferation and apoptosis and mitosis of epithelial cells. A great quantity data suggest that IGFs control the growth and hyperplasia of many carcinomas.The actions of IGF-I and -Ⅱare mediated via the type I. the IGF-Ⅱis slightly acidic with 67 amino acids. IGF-I and IGF-Ⅱact on a variety of mammalian cells in an endocrine, paracrine and autocrine manner to regulate cell proliferation, apoptosis, transformation and differentiation. Both IGF-I and-Ⅱare essential for normal human growth and development. Recently, the study from domestic and abroad have found that the expression of IGF-Ⅱgene increasing in majority cell lines and tissues of colorectal cancer. LOI of the IGF-Ⅱgene is found in colorectal cancer patients 5.1times than in healthy individuals. Imprinting of the IGF-Ⅱgene has been also used as a marker to predict the risk of colorectal cancer . Adults have a higher concentration of serum IGF-Ⅱthan IGF-I. Growth hormone regulates the expression of the IGF-I gene and it thereby mediates most of its actions through IGF-I, but itdoes not control the expression of IGF-Ⅱ. Therefore, the study of significance of IGF-Ⅱand colorectal cancer have important clinical value.The IGFBPs control the distribution of IGFs because of their higher affinity to IGFs, which is 2–50 times higher than that of the IGF-IR. The key function of the IGFBPs is regulation of the circulating bioavailability of the IGFs They inhibit the action of IGFs by high affinity binding, at the same time, some IGFBPs can alsor potentiate cancer cell growth under different circumstances. The IGFBPs are degraded by several proteases produced by colorectal cancer cells, some of which are specific to that binding protein and others are non-specific proteases that control the function and the tissue availability of IGFBPs. These proteases cleave the IGFBPs into fragments with lower affinity for the IGFs. which increase the availability of circulating free IGF. Thus, the IGFBPs have been very important factors in carcinogenesis. IGFBP-4 is unique in that it is the smallest IGFBP and exists in both glycosylated and non-glycosylated forms. It is secreted by almost all colon cancer cell lines and it is regarded as unique inhibitory protein.Much of our current knowledge of IGFs and colorectal cancer, especially the knowledge IGFBP-4and colorectal cance ,is from in vitro studies, and no report is found in domestic. There is, therefore, a need for further in vivo studies to enable us to manipulate these knowledge to prevent and control colorectal cancer. Our research decide to analyze the relations between IGFs and the genesis and infiltration and differentiation and metastasis and prognosis of colorectal cancer, to approach the clinical significance of IGFs, through the detection of the expression of IGFs in tumor and normal and precarcierosis tissues. And further to detect the serum levels of IGF-Ⅱand IGFBP-4, compare with those of CEA,CA19-9, to approach their serum diagnostic value. We want to get more knowledge in vivo from the study , which can give benefit information for the diagnosis and therapy of colorectal cancer.Material and MethodsThe tumor and nomrmal surgical or endoscopic biopsy specimens from 48 colorectal cancer patients and 21 gastric cancer patients and 23 esophageal cancer patients were selected from our hospital. The high frequency electroblation by endoscope specimens from 20 colorectal adenomas patients.The serum specimens were from above-mentioned colorectal cancer and colorectal adenomas patients and 20 healthy persons.The expression of IGFs in tumor and normal tissues were determined by RT-PCR and immunohistochemical method. The serum levels of IGF-Ⅱ, IGFBP-4, CEA and CA19-9 were determined by radioimmunoassay and ELISA and electro-chemiluminometry method.SPSS10.0 software was adopted to analyze the experimental data of the IGFs expression .Results1. The expression of tissues insulin-like growth factorⅡ(IGF-Ⅱ), insulin-like growth factor I (IGF-I) and IGF-I receptor (IGF-IR) in colorectal cancer.1.1 The level of IGF-Ⅱand IGF-IR mRNA in cancer tissues were 0.979±0.436and 0.607±0.327, which were higher than those in controls (0.293±0.261 and 0.333±0.227, P﹤0. 05).The level of IGF-I mRNA was no significant difference found in two groups(.P﹥0.05). The expression percentage of IGF-Ⅱ, IGF-I, IGF-IR mRNA was no significant difference found in colorectal adenomas( P﹥0.05) ,but the lower expression percentage of IGF-ⅡmRNA was found in normal tissues (P﹤0. 01).1.2 The positive immunohistochemical expression of IGF-Ⅱlocated intracytolplasm.The positive rate of immunohistochemical expression of IGF-Ⅱin cancer tissues was 100%, higher than that in adenomas(65.0%, P﹤0. 05 ), and that in normal tissues(22.9%, P﹤0. 01).1.3 The level of IGF-ⅡmRNA increased gradually in normal tissues and adenomas and cancer tissues ( 0.293±0.261 and 0.633±0.484 and 0.979±0.436, P﹤0.01). Follow Dukes A and B and C and D, IGF-ⅡmRNA became higher and higher(P﹤0.01). And IGF-ⅡmRNA in tissues with severe dysplasia or tumor size≥5cm is significantly higher than those with mild /moderate dysplasia or tumor size<5cm ( P﹤0. 01, P﹤0. 05). There was no significant difference found in different anatomical site of cancer(p﹥0.05).2. The expression of tissues insulin-like growth factor binding protein -4 and MMP-7 in colorectal carcinoma.2.1 The amplification productions of IGFBP-4 mRNA were found in 89.6% cancer tissues and 80.0% adenomas tissues and 68.8% normal tissues.The level of IGFBP-4 mRNA in colorectal adenomas and cancer tissues were0.482±0.197 and 0.313±0.216 , higher than those in controls (0.186±0.166,P﹤0. 01 ) . Follow Dukes A and B and C and D, IGFBP-4 mRNA became lower and lower, Dukes D was the lowest. There was no significant difference found between different tumor size or anatomical site (P﹥0.05).But IGFBP-4 mRNA in tissues with Tubulovillous/villous adenomas is significantly lower than those with Tubular adenomas ( P﹤0. 01).The same result was found in severe dysplasia and mild /moderate dysplasia .2.2 The positive immunohistochemical expression of IGFBP-4 located intracytolplasm.The average integrate in normal and cancer and adenomas tissues were 0.896±0.881 and 2.250±0.910 and 3.500±1.011,which in tumor tissues were lower than those in controls (F=91.775,P﹤0. 01), and there were no immunohistochemical expression in 39.6% colorectal cancer .2.3 The amplification productions of MMP-7mRNA were found in all cancer tissues, weren't found in all normal tissues. The significant higher expression of MMP-7mRNA was showed in cancer tissues than normal tissues (P﹤0.01). And showed a relationship with the depth of infiltration and lymph node metastasis. The expression of IGFBP-4 mRNA was negative correlation with that of MMP-7(r =0.579,P﹤0. 01).3. The changes of serum insulin-like growth factorⅡand insulin-like growth factor binding protein-4 in the patients with colorectal cancer.3.1 The serum IGFBP-4 in colorectal cancer and adenomas patients and healthy people were (3.040±1.458) and (3.850±0.693)and (2.600±0.780)ng/ml,there was no significantly difference found during the three groups.3.2 The serum IGF-Ⅱlevels in patients were(0.79±0.24)ng/ml and ( 1.05±0.45 ) ng/ml, were significantly higher than those in controls ( 0.50±0.15) ng/ml (P﹤0.01), more higher in colorectal cancer than adenomas(P﹤0.05). In the patients with colorectal cancer, the serum levels of IGF-Ⅱin Dukes A and B and C were significantly higher than those in controls ( P﹤0. 01 ),Dukes D was no significant difference found ,and it lower than Dukes A and B and C (P﹤0. 01). There was no significant difference found between different tumor size or ananatomical site or degree of dysplasia and the level of IGF-Ⅱ(p﹥0.05).3.3 Additionally,the combined sensitivity of IGF-Ⅱand CA19-9 and CEA were higher than that of single item in patients with colorectal cancer ( P﹤0. 05). This study has shown that serum IGF-Ⅱmay be a tumor marker in individuals with colorectal tumors.4. The expression of insulin-like growth factor binding protein-4 in different gut carcinoma.4.1 The amplification productions of IGFBP-4 mRNA were found in 89.6%(43/48)colorectal cancer and 85.7%(18/21)gastric carcinoma and 86.9%(20/23)esophageal carcinoma, there were no difference in three groups. The expression level of IGFBP-4 mRNA in gastric carcinoma was higher than that of colorectal and esophageal carcinoma(P﹤0.01),and there was no significant difference found in different pathologic type carcinoma tissues(adenocarcinoma,mixed carcinoma,squamous cell carcinoma)(P﹥0.05).4.2 The positive rate of immunohistochemical expression of IGFBP-4 in colorectal cancer and gastric carcinoma and esophageal carcinoma was 60.4% and 71.4% and 60.9%, tumor tissues lower than that in controls ( P﹤0.05), but there was no significant difference found in three carcinoma tissues . 4.3 The expression of IGFBP-4 mRNA was higher in esophageal cancer tissues(0.503±0.245) than normal tissues(0.291±0.240,P﹤0.01). But more lower expression of IGFBP-4 mRNA were found in tumor tissues with senosa infiltration and lymph node metastasis( P﹤0.01). There was no significant difference between different age and sex and tumor size (P﹥0.05).Conclusions1. IGF-Ⅱand IGF-IR and IGFBP-4 may be related closely with the development and advancement of colorectal cancer, there was no clearly relations between IGF-I and colorectal cancer.2. IGF-Ⅱimproved the development and advancement of colorectal cancer. The expression of IGF-Ⅱincreased gradually in normal tissues and adenomas and cancer tissues, the up-regulation expression of IGF-Ⅱmay be related with Dukes stage and differentiation degree of colorectal cancer and tumor size, it was very important to early diagnosis and evaluation of prognosis of Colorectal carcinoma.3. IGFBP-4 may be regarded as a tumor inhibitor, contribute to the development and advancement of colorectal cancer, and related with Dukesstage and differentiation degree of colorectal cancer and pathologic type of colorectal adenomas. the expression of IGFBP-4 mRNA was up-regulation in early cancer and was down- regulation in late cancer. To investigate the expression of IGFBP-4 mRNA may be benefit to prognosis of colorectal carcinoma .4. The marked effects IGFBP-4 produced were chiefly in local tissues, the clinical significance of serum IGFBP-4 is limited. The expression of IGFBP-4 mRNA and protein were different, it may be concerned with the regulation of post-transcription translation and MMP-7 produced by cancer.5. The changes of serum IGF-Ⅱhad a closely relationship with the development and advancement of colorectal cancer. The combined use of serum IGF-Ⅱand CEA and CA19-9 is an useful adjuvant diagnostic measure for colorectal cancer.6. The expression of IGFBP-4 in local tissues were no deference in different anatomical site and pathologic type of gut carcinoma . And its functions in different tumor were similar, the lower expression of IGFBP-4 mRNA was chiefly benefit to the development of gut late cancer.