The Effects Of Combination Of Octreotide And 5-FU On The Proliferation And The Expression Of Mutant P53 Protein In Human Colorectal Cancer Cells In Vitro

Colorectal cancer have a relatively higher incidence rate and abad prognosis and have been ordered to 4 or 5 position in malignanttumor notations in China. The colorectal cancer etiology has provedthat the factors of dietary constitution, the intestinal cavity chronicinfectious disease and the individual genetic character has a closeassociation with the colorectal tumorgenesis. The development ofcolorectal cancer is a multiple and complicatable procession. It may bean important clue of the study in gene mutation in the research in thecolorectal cancer etiology. The p53 tumor suppressor gene plays animportant role in preventing cancer development, by arresting orkilling potential tumor cells. Mutations within the p53 gene, leading tothe loss of the p53 activity, are found in about half of human cancers.This is the most important change in the tumor, suggesting that themutation of this gene would be a main factor of pathogenesis. Mutational P53 gene lost the supervision of the organization cell,Can't make decrepitude cell, excrescent cell press normal proceduredeath or clearances but propagate constantly in the body;On the otherhand, mutant p53 have the function of suppressing apoptosis, it is inconjunction with suppression apoptosis gene (Bcl22) to obstruct theexcrescent cell apoptosis, prolong existence time of cells, increase theunsteady factor, interfere DNA repair process, allow the existence ofthe essential gene of the tumor development, and make the tumor cellfurther differentiation. P53 protein is performance of the p53 genefunction. It mainly situate nucleolus of the cell nucleus. The normalp53 protein is easy to hydrolysis in the cell, half-life is 6-30 minutes,and can't be detected by standard immunohistochemistry, but mutionp53 protein can be detected by standard immunohistochemistrybecause of conformation altered, half-life extended. so p53 proteinthat can be detected by standard immunohistochemistry means genemutation. The P53 gene mutation is in accordance with expression ofP53 protein in the tissue.When the cell lack of wild p53 protein but containing mutationp53 protein contacts with the outside source or inside the DNA injuryfactors, the content of mutation p53 protein goes up, but this kind ofmutation p53 can't induce growth retardation and apoptosis, butpromote the cancer cell growth and deadexis. mutation p53 proteinsuppress activation of wild p53 protein through dominant depressioneffect. the depressant effect is completed through mutation p53 proteincombining with wild p53 protein and forming oligomerizationcompound. On the other hand, when anti-oncogene p53 occursmutation, mutation p53 protein expressed by it make transcriptionmodulin (Daxx) lose the function of apoptosis inhibition. Mutationp53 protein stimulate and promote the growth of the cell. Mutationp53 protein combine with the virus oncoprotein, so is one kind oftumor enhancing factor. In short, mutation p53 have something topromoting tumor growth with numerous factors.The normal gastrointestinal mucosa doesn't express p53 protein,and some experiments showed that well-differentiated adenomas,including familial multiple polyposis that is an autosomal dominantinherited disease and large intestine polypus express p53 at lowerlevel than colorectal cancer. This result supports the p53 genemutation rises the important function in the occurrence of colorectalcancer.It shows that somatostatin (SST) which inhibits proliferation ofgastrointestinal cancer cells, could regulate the proliferation ofgastrointestinal cancer cells. Somatostatin and its analogues inhibitproliferation of cancer cells directly by inducing G1 cell cycle arrestor apoptosis. As a result of the inhibition of secretion of growthpromoting hormones and growth factors,angiogenesis or blood supplyto the tumor, indirect anti-proliferation can also be mediated by SST.In this study, we would provide a few certain proofs for clinic therapywith the effects of combination of Octreotide and 5-FU on theproliferation and the expression of p53 protein in human colorectalcancer Cells in vitro.MethodsThe primary cell of colorectal cancer were cu1tured in vitro andseeded in to culture plates. According to tumor cell counting, theinhibition rate of cells of every experiment groups were: 6.95%(0.1ug/ml), 9.81% (0.5ug/ml), 15.80% (1.0ug/ml), 21.29% (2.0ug/ml),25.39% (5.0ug/ml). Observe inhibition of 0ctreotide on humancolorectal cancer cel1s in vitro were determineted by MTT assay atdifferent concentrations of 0ctreotide and the growth rate werecalculated;Observe the efficacy of 0ctreotide against the cancer cellswhen combined with 5-FU. Indirect immune fluorescent labeling andflow cytometry were employed to investigate expression of mutationP53 protein.ResultsThe results of experiment showed that 0ctreotide can inhibit thegrowth human colorectal cancer Cells. The inhibitory effects wasdos-dependent: the more affective when the conceniiation of0ctreotide was higher. Both 5-Fu and OCT inhibited the growth ofcancer cells, combination of Octreotide and 5-FU enhance the action,inhibition ratio is higher than 5-FU and OCT alone. The inhibition rateof cells of every experiment groups were: 15.80% (OCT1.0ug/ml),35.08% (5-FU10ug/ml), 47.51% (5-FU10ug/ml+OCT1.0ug/ml)Flow cytometric analysis demonstrated a decreased FI, The expressionof mutant p53 protein is decreased.Conclusions:1. Octreotide can inhibite the proliferation of human colorectalcancer cel1s in vitro and the inhibitory efects was dose-dependent.2. Combination of Octreotide and 5-FU enhance the action,inhibition ratio is higher than 5-FU and OCT alone in vitro.3. Both Octreotide and 5-FU can inhibite the expression ofmutant p53 protein in the cancers cell, inhibition efficacy is higherthan 5-FU and OCT alone in vitro,so this may be One of themechanisms that Octreotide can enhance inhibition ratio ofcolorectal cancer Cells of 5-FU.