| ObjectivePTEN, a kind of anti-oncogene, is the first anti-oncogene which functions as aphospholipid phosphatase, it regulate cell proliferation negatively. Ki67, a kind ofnuclear antigen, is related closely to cell proliferation, and is one of the most usefulsymbol of cell proliferation. Both of them are related to tumor behavior closely. Thepurpose of the study is to definitude the relation among PTEN,Ki67 and the grademalignancy of glioma, and to explore the mechanism of action of PTEN further, and tointroduce the directory meaning to clinic.Methods1．Patient selectionTissue samples of gliomas(n=40) and non-tumor brain tissues(n=10) wereobtained from patients who underwent surgery in the department of neurosurgery ofShengjing hospital of China Medical University from December 1,2003 to November30th,2005．All tumors were graded according to World Health Organization criteria.2．ImmunohistochemistryA total of 50 formalin-fixed and paraffin-embedded specimens was available forthis study. Expression of PTEN and Ki67 was immunohistochemically investigated.Paraffin sections were cut at 5um thickness, deparaffinized with xylene and rehydrated.After endogenous peroxidase activity was blocked with 3 %H0 for 10 min at room tempreture, the section were treated with 0．01 mol/liter citrate(PH=6．0) in a 500-Wmicrowave oven for 10 min for antigen retrieval. After blocking nonspecific reactivitywith normal nonimmunone serum for 10 min at room tempreture, the section wereincubated with anti-PTEN and anti-Ki67 monoclonal antibody for 1 hour at roomtempreture and then with biotin-conjugated second antibody for an addition 1 hour at37C. Positive signals were detected by the S-P method with UltraSensitive S-P kit.Sections were also counterstained with hematoxylin.3．Result determinationStrong reactions in the cytoplasm were considered positive for PTEN, Strongreactions in the nuclei were considered positive for Ki67．Under the fluorescope,randomly take five high-powered fields of vision to count the positive cell percentageof PTEN and Ki67．4．Statistical methodsThe analysis was progressed with statistics software SPSS11．5．x-test was usedto compare the expression of PTEN and Ki67 in gliomas and non-tumor brain tissues.Fisher exact probability test was used for some cases(n<40) . Non-parametic Spearmanrank correlation coefficients were used to assess the degree of association betweenPTEN and Ki67．Statistical significance was defined as P<0．05．ResultsAll of the 50 speciments studied were positive for PTEN. For the expression ofPTEN, there is a significant difference not only between non-tumor brain tissue andgliomas, but also between the well differentiated gliomas and the poorly differentiatedones(P<0．05) .There is no expression of Ki67 in the non-tumor brain tissue, the positiveexpression rate in the the well differentiated gliomas is lower than that in the poorlydifferentiated ones significantly.There was a strongly negative correlation between PTEN and Ki67 (r=-1．00 , P<0．05) .DisscussionAccording to the statistic of WHO in 1992, the incidence rate of primary braintumor is 2-19 per 100,000 people, and about 40-50% of those are gliomas. Becausegliomas often grow infiltratively, it is very difficult to cure them.Recent studies of molecular biology believed that the occurrence and developmentof gliomas were related to the abnormality of genes closely, and considered that tumoris a kind of dicease of gene. The distinctive pattern of manifestation of tumor isincoercible cell proliferation. In normal situation, anti-oncogene can supperss thehypernomic growth and transform of cell. So the deficiency of functionalanti-oncogene will result in the failure of normal control manchanism of cellproliferation.PTEN is a kind of anti-oncogene which is located in the 10 chromosome andfound in 1997, it is so far the first anti-oncogene which functions as a phospholipidphosphatase. Researches show that the mutation and deletion of PTEN are related tothe occurrences of gliobastona, high-degree malignant prostatic carcinoma, andoophoroma closely.The detection of tumor proliferation activity is very important to judge themalignant degree, predict the biological behavior, evaluate prognosis, and selectappropriate therapeutic measure. Ki67 is a kind of nuclear antigen which is relatedclosely to cell proliferation, and is one of the most useful symbol of cell proliferation.In recent years, PTEN and Ki67 have been studied by experts in many fields and alot of achievements have been obtained. But it is unusual to combine PTEN and Ki67and to study the expressions of them in gliomas. The purpose of the study is todefinitude the relation among PTEN,Ki67 and the grade malignancy of glioma byresearching the expressions of PTEN and Ki67 in gliomas throughimmunohistochemistry, and to explore the mechanism of action of PTEN further, and tointroduce the directory meaning to clinic. ConclusionThe results show that the expression of PTEN presented downtrend with the riseof tumor degree, while that of Ki67 rose gradually, and there was a strongly negativecorrelation between PTEN and Ki67 (r=-1．00 , P<0．05) , which suggest that PTEN isrelated to cell proliferation closely. The supperss of PTEN to tumor has very importantclinical significance in selection of target gene for treatment of gliomas.
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