| The occurrence and development of tumors is a multi - stage evolution concerning many aspects and factors in which oncogene and tumor - suppressor gene play an important role.P53 gene is a tumor - suppressor gene. Its bio - chemical function is a transcripdon factor and biological function is the check point for DNA damage in G1 period. About 50% of the human tumors involve in the mutadon of P53 gene. PCNA is a 36KD nucleic protein. PCNA labeling index is an objecdve indicator for evaluation of cell proliferation state. It is reported in most literature that PCNA labeling index is closely related with tumors staging, curative effect and prognosis.Astrocytoma is one of the common intracranial tumors in the brain. Its biological behavior has something to do with histological gradation. The present paper makes a qualitative and quantitative study of P53 and PCNA in forty - eight cases of human brain astrocytoma by use of immunohistochemistry technique and explores their expressive meaning in the astrocytoma.Materials and Methods1. Experimental materialsAll the cases came from the wax - encapsulated tissue specimens in file for the hospitalized patients from 1998 to 2001 collected by the neurosurgery department of No. 2 Clinical hospital of China Medical University. These patients had a pathological diagnosis of astrocytoma after surgery. There are forty - eight cases, of which 14 belong to star cell tumors ( Class I - II ) ; 22 cases belong to anaplastic astrocytoma (Class III) ; and 12 cases belong to glioblastom (Class IV). The chief reagents are mouse anti - human monoclonal antibodies and mouse antihuman PCNA monoclonal antibodies. The optimal working dilution concentration is 1:75 with S - P immunological reagent box and DAB chromogenic reagent box.2. Experimental methodsExperimental specimens are prepared into sections with a thickness of 4 fun. Experimental operation should be made in strict accordance with immunohistochemistry method, namely, the streptococcus antibiotic protein - peroxidase (S -P process) method.3. Determination of results(1) P53 determination criterion; under the fluorescope, take ten high - powered fields of vision where cells are concentrated and count 1000 cells. The chromaticity - positive cells are expressed with brown nucleus. Count the percentage of positive cells. If the percentage of positive cells is< 10% , it is ( - ) ; <30% , ( + ) ;<50% , ( ++ ) ; >50% ( +++ ). <10% belongs to low expression while > 10% high expression.(2) PCNA determination criterion; if brown chromatin granule appears in the nucleus, the chromaticity is positive. Under the fluore-scope, randomly take ten high - powered fields of vision to count the positive cell percentage of PCNA in 1000 tumor cells. If the positive cell percentage is <25% ,it is( - ) ; <50% , ( + ) ; <75% ,(++); >75% , ( +++).4. Statistical analysisMake a statistical evaluation of the relationship between the pathological category ( gradation) of the astrocytoma , P53 and PCNA by use of test and correlation analysis.Results1. P53 is chiefly expressed in highly malignant astrocytoma and is closely related with the histological type and pathological gradation of tumors.2. The percentage of PCNA positive cells increases with the upgrading of the pathological gradation of astrocytoma. Besides, the pathological gradation is positively related to the proliferation index remarkably.3. The astrocytoma PCNA - LI with positive expression of P53 is higher than the negatively expressed astrocytoma of P53 . The difference is significant and P53 is positively related to PCNA expression in astrocytoma.DiscussionP53 gene is located at human No. 17 chromosome (17P13.1) and isdivided into wild type ( Wt) and mutational type ( Mt). The wild type P53 gene plays a major role in maintaining normal cell growth and inhibiting malignant proliferation. When the cells which lack wild type P53 function, but contain mutational type P53 are in contact with exogenous or endogenous DNA...
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