Survivin Expression In Ovarian Carcinoma And The Inhibition Effect Of Its Antisense RNA On Tumor In Vivo

Ovarian carcinoma is the most common cause of death among all gynecologic malignancies. The overall 5-year survival rate of patients is only about 25%³0%. It heavily threaten the health of women. Therefore, it is very important to explore new therapy method for Ovarian carcinoma. Nowadays, with the rapid development of molecular biology, it is generally accepted that the tumorigenesis and tumor progression are closely related to the changes of tumor cell biology. However, very little is known about the exact sequence of celluar and molecular events contributing to the development of ovarian malignancy.Survivin has recently been identified as a novel inhibitor of apoptosis (IAP). Unlike other members of the IAP family, survivin is characterized by a unique structure that contains a single baculovirus IAP repeat and no carboxyl-terminal RING finger motif. It is expressed in many common human cancers, but its expression is lost or down-regulated in normal adult tissues. Survivin blocks a common downstream part of two major apoptosis, the mitochondrial pathway and the death receptor pathway, by directly inhibiting terminal effector caspase-3 and caspase-7, and by interfering with caspase-9 activity. It also regulates the G₂/M phase of the cell cycle by associating with mitotic spindle microtubules. Meanwhile, the mean apoptosis index(AI) in survivin-positive tumors significantly lower than the mean AI in survivin-negative tumors. Therefore , many scholars considered that survivin could suppress apoptosisand accelerated cell proliferation. Immunological treatment or gene therapy targeting survivin may be come true due to its differential expression in tumors versus normal tissues. This targeting therapy may selectively increase susceptibility of cancer cells to apoptosis-based treatment, and increase overall survival rate of patients.Along with going deep into the research of survivin gene, survivin will become a new diagnosis and therapeutic target in tumor.We study the expression of survivin protein in ovarian carcinoma and benign ovarian tumor, their relationship with proliferation activity of tumor cell measured by PCNA index and their clinical significance in ovarian carcinoma. Besides, This study was further designed to explore the inhibition effects of antisense survivin(SVVas) RNA on the growth of the human ovarian carcinoma transplanted subcutaneously in nude mice.ObjiectiveTo study the expression of survivin protein in ovarian cancers, their relationship with proliferation activity of tumor cell measured by PCNA index and their clinical significance in ovarian cancers . And further explore the inhibition effect of antisense survivin RNA on the growth of the tumorigenic ability of the transfected SKOV3 cells transplanted subcutaneously in nude mice. We want to interprete the possible molecular mechanisms and supply valued diagnosis and prognosis indicators for clinical workers and a new method for gene therapy.Methods1 The expression of survivin, PCNA protein in 38 cases of ovarian carcinoma, 12 cases of benign ovarian tumors were detected by immunnohistochemistry methods.2 Twenty-four nude mice were subcutaneously implanted with human ovarian epithelial cancer cell lines SK.OV3 on the back of nude mice, then divided into three groups. SKOV3, SKOV3/neo and SKOV3/SVVas cells were transplanted respectively. Since the sixth day, we measured the longest and the shortest diameter by ruler. Thechanges of tumor volume were observed and the tumor growth inhibitory rate was calculated.3 Statistical analysis: The SPSS statistical package program 11.0 was used for all analyses. Associations between the variables were tested by x2 test , Wilcoxon signed rank test, t test and two-way ANOVA. P<0.05 were deemed significant. P<0.0l were deemed highly significant.Results1 According to immunnohistochemistry results in ovarian tissue, the positive rate of survivin protein expression in ovarian carcinoma and benign ovarian tumors were 81.58% and 33.33% respectively, benign and malignant tumor had significantly difference (PO.01).2 Labeling indexs of PCNA was (61.03±22.77)% in ovarian carcinoma, and (23.75±7.63)% in benign ovarian tumors. There was significantly difference between benign and malignant tumor(P<0.001).3 Labeling indexs of PCNA in ovarian carcinoma with negative expression of survivin was (25.71±9.76)%, and that in ovarian carcinoma with positive expression of survivin was (69.00± 16.25)%, there was statistical significance(P<0.001).4 There were closed relationship between the expression of survivin and clinical stage, histological grades, lymph node metastasisand ascites, but no relationship with histological classification.5 The tumorigenic ability of the SVVas transfected SKOV3 ovarian cancer cell lines was decreased. 5 of 8 nude mice were found tumor, and the tumorigenic rate was 62.5%. The growth rate of its tumor became very slow . And the first time that tumor can be detected was raised up to 14 days(P<0.05).Conclusion1. The expression of survivin in ovarian carcinoma were significantly higher than those in benign ovarian tumors. It suggested that survivin is involved in tumorgenesis and tumor progression, and survivin may be a good biomarker in early diagnosis and superviseing the development of ovarian carcinoma.2. The PCNA proliferation index increased with the pathologic aggressiveness of ovarian carcinoma. It showed that the overproliferation of ovarian carcinoma cell was an important event in aggressiveness of ovarian carcinoma.3. There were closed relationship between the expression of survivin and the PCNA proliferation index. It suggested that abnormal expression of survivin may lead to aggressive proliferation of ovarian carcinoma cell.4. There were closed relationship between the expression of survivin and clinical stage, histological grades, lymph node metastasis and ascites. It suggested that survivin may be used as a sign to estimate the curative effect and to appraise the prognosis of ovarian carcinoma.5. Survivin antisense RNA could lead to cell apoptosis by inhibiting the expression of survivin in ovarian carcinoma,which could inhibit cell proliferation in vivo.