Comprehensive Study Of53BP1among The Development Of Ovarian Cancer

Ovarian cancer is a common aggressive disease and is the fifth leading cause of cancer-related death in women. The life-time risk of this highly lethal disease is approximately1.4%. Due to the lack of obvious symptoms, substantial delays in diagnosis are quite common, and the overall survival rate for ovarian cancer has only slightly increased over the last30years in spite of advances in surgery and chemotherapy. Therefore, understanding of the tumor molecular biology is an essential step for the selection of the most effective treatment strategy for ovarian cancer.Tumorigenesis is a result of the accumulation of genetic changes. Genomic instability leads to the transformation of normal cells to cancer cells. This includes aberrant reduction or loss of tumor-suppressor genes and activation of proto oncogenes.P53binding-protein1(53BP1) was one member of DNA damage repair family. The functions of53BP1range from participation in DNA-damage repair to negotiating cell cycle checkpoints. However, the knowledge of the role of53BP1in ovarian cancer is still rudimentary. Here, we presented a preliminary analysis of53BP1in the prevention of ovarian cancer development, which includes the following three parts:1.53BP1Suppresses Tumor Growth and Promotes Susceptibility to apoptosis of Ovarian Cancer Cells through Modulation of Akt Pathway2.53BP1Inhibits the Invasion and Regulates the Chemotherapy Resistance of Ovarian Cancer Cells3. High Level of53BP1Decreases the Tumorigenic Ability of Ovarian Cancer Cells BACKGROUND:53BP1have been extensively studied as a key component of DNA damage response, but little is known regarding the role of53BP1in preventing tumor development. OBJECTIVE:The present study was designed to assess the impact of the modification of53BP1gene expression on the biological behavior of ovarian cancer cell lines and to elucidate the cellular pathway(s) triggered by53BP1in cancer cells. MATERIALS and METHODS:DNA liposome transfection technology was employed to increase and to knock down the expression of53BP1in SKOV3cells. Viability, clonigenicity and cell cycle profiles were evaluated. Cell apoptosis was analyzed using flow cytometric assay. The expression of proteins related to apoptosis and cell signal transduction were assessed using western blot. RESULTS:Increased expression of53BP1decreased the viability and the clonigenicity(34±9clonies/500cells vs.152±22clonies/500cells), and induced G2/M arrest (26.68±2.11%vs.13.02±1.30%) and apoptosis of the treated cells (23.48±3.20%vs.9.34±2.12%)(P<0.05). The protein expression of Bax and P21wafl/cip1was upregulated, while the levels of Bcl-2and p-Akt were reduced at a statistically significant level. In contrast, deregulation of53BP1significantly increased proliferative ability. CONCLUSION:Collectively, our data suggest that53BP1is involved in several important steps in controlling cell proliferation and growth and preventing tumor development. BACKGROUND:A major problem with ovarian cancer is metastasis and the development of intrinsic or acquired drug resistance. OBJECTIVE:The aim of the present study was to elucidate whether53BP1could be a regulator for invasion and chemotherapy resistance of SKOV3cells, and to identify proteins associated with the molecular mechanisms underlying this coordinate regulation. Stable transfection was obtained by a53BP1expressing vector to overexpress53BP1in SKOV3cells, and a53BP1interfering vector to knockdown the expression of53BP1. The invasive ability of the transfected cells was observed by transwell test, and the expressions of MMP-2and MMP-9were assayed by Gelatin enzyme test. In addition, the effects of53BP1on chemosensitivity of the SKOV3cells to cisplatin were investigated by MTT assay and western blot. RESULTS:Compared to the control group, the average number of invading cells in SKOV3/pLPC-53BP1were decreased from230±58to45±12(P<0.05), and the protein expression of MMP-9was significantly inhibited. However, the chemosensitivity of SKOV3/pLPC-53BP1cells to cisplatin decreased significantly (IC50:7.58±0.51μg/ml vs. IC50:2.98±0.27μg/ml P<0.01). The decreased chemosensitivity to cisplatin might be associated with the induced expression of p-Akt and Bcl-2, and with the concomitantly decreased expression of Bax and P21waf1/cip1. In contrast, deregulation of tumor-intrinsic53BP1significantly resulted in enhanced invasion and up-regulated chemosensitivity to cisplatin of SKOV3. CONCLUSION:Our data demonstrates that the anti-invasive ability and up-regulated chemoresistance to cisplatin of53BP1in SKOV3cells. BACKGROUND:Animal models with transplantable tumor could mimic the initiation, progression and metastasis of human cancers, and provide unique tool to under the occurrence and development of carcinoma. Whether tumor transplants success or not depends on the viability and growth ability of tumor cells. OBJECTIVE:The present study was conducted to explore the potential inhibitory ovarian tumorigenesis of53BP1in nude mice. MATERIALS and METHODS:We have established and validated stable epithelial ovarian cancer cells (SKOV3/pLPC-53BP1, SKOV3/pSUPER-53BP1, SKOV3/pLPC-vector and SKOV3/pSUPER-vector). The above cells were inoculated subcutaneously into nude mice. The tumorigenic ability of above ovarian cancer cell was compared by nude mouse xenograft models (n=8mice per group). The time of development tumor of each group was detected. Furthermore, the survival of each mouse bearing tumor was assessed with Kaplan-Meier method and evaluated with log-rank test. RESULTS:All nude mice were successfully transplanted ovarian cancer cells. We found that the time and the size of development tumor was relevant with the expression of53BP1in SKOV3cells (SKOV3/pLPC-53BP1group vs. SKOV3/pLPC-vector,28.50±2.07days vs.22.88±2.90days,0.53±0.12cm vs.1.12±0.23cm P<0.05. SKOV3/pSUPER-53BP1vs. SKOV3/pSUPER-vector,14.88±1.46days vs.20.75±5.34days,2.52±0.72cm vs.0.94±0.11cm P<0.05). The Kaplan-Meier curves demonstrated that high levels of53BP1were significantly extended overall survival of the mice bearing ovarian cancer (SKOV3/pLPC-53BP1group vs. SKOV3/pLPC-vector,110±5.15days vs.100±2.97days, P<0.01. SKOV3/pSUPER-53BP1vs. SKOV3/pSUPER-vector,87±5.22days vs.96±7.92days, P<0.05). CONCLUSION:Tumorigenic assays in mice show that overexpression of53BP1substantially impairs tumor growth, and improves the overall survival of mice.