The Expressions Of Livin And Caspase-3 Gene In Colorectal Cancer Tissues And Their Significance

Background:With the rise in incidence of colorectal cancer, more and more peaple were facing the threaten of colorectal cancer in China. Mechanism of tumor ocurrence is unclear. At present, it is believed that incidence of colorectal cancer has correlation with cell proliferation and apoptosis.The use of combined therapeutic approaches (surgery, chemotherapy, and radiation) for patients with colorectal carcinoma does not evidently improve outcomes. The five-year survival in patients is about 50 percent, respectively. For many years, the use of chemotherapy and radiotherapy as adjuvant treatment after complete resection of cancers was thought to be ineffective for the treatment dosage was not sufficient to avoid prominent toxic effect and other adverse reactions including diarrhea, nausea, vomiting and bone marrow suppression. How can we do early discovery and early diagnosis to colorectal cancer? How can we enhance the sensitivity of human organism to chemo-therapy and radiotherapy and immune-therapy to elevate curative effect of combined therapy of colorectal cancer? These are constantly puzzle that madicine workers try hard to make a breakthrough. How these problem be solved? With the advent of new genetic and molecular-pathologic techniques, It is more and more important that inhibitor of apoptosis protein (IAP) is applied to clinical diagnosis and treatment in many tumors. IAP significant expressions that made decrease apoptosis has intimate correlation with incidence of tumor. Livin, a novel IAP, discovered in 2000, is a protein gotten from homo-sapiens genome cDNA Lib clone. Livin gene is located in Homo sapien twentith chromosome, total length 4.6kb, and includes seven extrons and six introns. It is composed by two splicing allosterism body Livin-αand Livin-β. Livin-β, encodes 280 amino acids, is 54 base pair (BP) fewer than Livin-αin sixth extron. Livin-αencodes 298 amino acids.Integrity Livin structure is a sort of suppressing apoptotic kyto-protein. After Livin combines with (Caspase)-3, 7, 9, it can suppress Caspase activity and block dead signal transduction. Alike other IAP members, Livin depends on BIR structure to resist apoptosis. Livin can suppress TNF-αand CYTC pathway. There are different reports about Livin's location in cell.Livin has very important role to profit diagnose many tumors, such as malignant melanoma, lung cancer, gastric carcinoma and so on. It can also be used the judgement of bladder cancer post-technic recurring. It is paid more and more people attention to value of Livin in curability areas.Research shows that Livin high expression is real cause of leukemic cell drug resistant.Moreover to obstruct the expression of Livin can promote leukemic cellur apoptosis and reinforce chemotherapeutics antitumous effect. It will establish a new pathway in treating leukemia. Immunotherapy of target for Livin gene is uninterrupt being studied. A clinic first stage empirical study discovered that tumor immunotherapy had had clinical curative effect to those patients of melanoma entero-metastatic.Livin gene can take as immunoregulation inducing tumor destructive target. So Livin gene is becoming a hot spot of tumor investigation. However, it is rare reported in internal and overseas whether Livin gene has correlation with mechanism of colorectal carcinoma occurrence, invasion and lymph node metastasis, as well as taking as early diagnosis and therapic target.At present, it is believed that mechanism of tumor ocurrence has correlation with cell proliferation and apoptosis. Cell apoptosis is a gene controlling cellular autonomy death process and is to retain homeostatic significance mechanism. At present, it is common that a series of ordered cascade reaction, had correlation with apotosis developing in cell, is from Caspase protease activation. Caspase-3 is importment performer in cell apoptosis downstream. There were two kinds of classic apoptosis pathway, including in ecto-pathway and kyto-pathway. In ecto-pathway, dead signal depend on the integration of dead ligand and dead receptor. Following, death domain of dead receptor integrate with signal trans-molecule (e.g. FADD). After FADD connect with DED of Caspase-8 proenzyme, its synthesis for death induction signal compounds. At the same time, Caspase-8 is activated. Activated Caspase-8 makes BID split to make chondrosome release CYTC or directly activate Caspase-3 and other downstream Caspase. In kyto-pathway, kyto-dead signal, such as DNA, injury, toxin and ATP exhaust and so on, may induce to make chondrosome release CYTC. CYTC, Apaf-1 and dATP connect with Caspase-9 proenzyme to form apoptosis Complex. Caspase-9 is released to activate. To follow, downstream Caspase-3 is activated to degrade substrate to make cell apoptosis.It is proved that a few cell apoptosis mark signals, such as chromatosome condense and DNA gragmentation, have directly correlation with Caspase-3. After treating cell with human r-hCTGF, IL-4 and CSE, it is showed for Caspase-3 activation and cell apoptosis model change. Moreover, apoptosis can be controlled by Caspase-3 suppressor.Inhibitor of apoptosis proteins (IAPs) are Caspase-3 suppressor. A lot of research had been deeply made about dependablity of some IAP members and Caspase-3. However, relation of Livin and Caspase-3 in colorectal cancer is rare reported.This subject aims at seeking a new road for diagnosis and treatment of colorectal cancer by studying the altered expression of Livin and Caspase-3 gene at the levels of molecule in colorectal cancer tissues and their significance.It is demonstrated that the expression of Livin gene in colorectal cancers was higher than that in their surrounding mucosa by RT-PCR and Western Blot methods in this study. Livin expression had no significant correlation with pathological type and lymphatic metastasis and Dukes stage of colorectal cancer patients. Livin expression has closely correlation with the malignance of colorectal cancer. In experiment second chapter, by immunohistochemistry methods, we detected that Livin proteinum expressed in cytoplasm and was high expression in cancers. In contrast, colonic adenoma and pulypus and normal colonic mucosa did not express Livin. The expression of Livin proteinum had significanc correlation with differentiation level of colorectal cancer. The research illustrated that Livin gene activation has correlation with occurrence and development of colorectal cancer. Imbalance of apoptosis trigger gene Caspase-3 and apoptosis suppressor gene Livin participate nosogenesis of colorectal cancer.By immunohistochemistry methods, we detected that Livin proteinum was seventy percent (42/60) high expression in colorectal cancers. The expression of Livin in cancer was higher than that in normal colonic mucosa. So we may consider that tumor have just up-regulation of anti-apopotosis role through over-expression of Livin in cell karyomitosis to retain tumor cell proliferation activity. So Livin had correlation with human colorectal tumorigenesis. Moreover, we even more discovered that in well and moderately differentiated cancers, Livin expression was significantly lower than that in poor differentiated cancers(P<0.05). However there only are two Caspase-3 positive expression in all colorectal cancer patients. It indicates that implement of Livin anti-apoptosis mechanism is through Caspase path. Expression rate of Caspase-3 in normal colonic mucosa and colorectal cancers reduce by turns. So we may consider that lower expression of Caspase-3 had correlation with human colorectal tumorigenesis and progression. In well and moderately differentiated cancers,Caspase-3 expression rate was significantly higher than that in poor differentiated cancer. It indicates that expression of Caspase-3 had correlation with differentiate degree of colorectal cancer. Positive expression of Caspase-3 in colorectal cancer maybe indicate that cancer cell has well differentiated and light disorder of regulation mechanism and rather thinness cancer cell proliferation.It is manifested by these results that Livin and Caspase-3 may play important roles in human colorectal tumorigenesis through the inhibition of apoptosis and acceleration of proliferation activity. Livin can direct effect on Caspase-3 and suppress it's activity. This make apoptosis course block, thereby promote uninterrupt proliferation of colorectal cancer cell.In a word, Livin, a novel apototsis-suppressing gene, may provide a new pathway with diagnosis and treatment of tumor and become a new index to observe curative effect.The creativity of the research is: we study the expressions of Livin and Caspase-3 gene in colorectal cancer tissues and their significance. In molecular level, it confirms that research on Livin has necessity and significane in colorectal cancer. Livin gene, a novel apotosis suppressor gene, it's activation has correlation with occurrence and development of colorectal cancer. Livin gene will be a promising target of diagnosis and treatment of colorectal cancer.