Mechanism Of Proliferation And Metastasis Effect Caused By LRP16 Genein Breast Cancer

The mobidity of breast cancer, a kind of malignant tumor which threatens the health of the women greatly are increasing, although great development has been achieved in its diagnosis and treatment. The investigations of the genes related to the malignant progress of breast cancer are hope to help increase the cure rate and decrease the motility. Previous studies showed that estrogen can upregulate the expression of LRP16, a human gene cloned from the PBL of the healthy adult, and overexpression of this gene can stimulate the proliferation of MCF-7 breast cancer cell, but the concrete molecular biological mechanism was still unknown. This study investigated this problem and proved that LRP16 can be used as an molecular marker to analysis the prognosis of breast cancer. The study can be divided into two parts:一, Molecular Biological Mechanism of Proliferation and Metasta-sis Effect Caused by LRP16 Gene in Breast CancerObjective: To investigate the molecular biological mechanism of proliferation and metastasis effect caused by LRP16 gene in ERα positive MCF-7 breast cancer cell. Methods:(1) ERα mode-promotor or LRP16 promotor S10 controlled luciferase expression vector 3 ×ERE-Luc or pGL-3-S10 was cotransfected with ERα cDNA and LRP16 cDNA [or LRP16 specific siRNAs ( LRP16-siRNA374, LRP16-siRNA668 ) and control siRNA ( Control- siRNA) ] into ERα positive MCF-7 cell, then the relative luciferase activity was measured with Dual-luciferase Reaport Assay 1000 Systems.(2) Northern blot was used to determine the expression levels of ERα terget genes E2F1, RARa, c-fos, MTA₃, cathepsin D, Snail, Slug in response to estrogen exposure when LRP16 was depressed; The expression of cyclin D1 and E-cadherin in response to estrogen exposure when LRP16 was depressed was determined with Western blot. Results:(1) The reportor activitives of 3×ERE-Luc and pGL-3-S10 was enhanced by LRP16 and depressed by LRP16 specific siRNAs in adose-dependent manner,This effect was abolished when estrogen was deprived.(2)The up-regulated responsiveness of estrogen- induced genes by estrogen, included E2F1, RARa,,c-fos and MTA₃, but not cathepsin D , Snail, Slug were attenuated. (3)The induction of cyclin D1 by estrogen was repressed in LRP16-inhibitory MCF-7 cells, but E-cadherin was increased. Conclusions:(1) LRP16, a terget gene of estrogen can feedbackly enhance the transcriptional activition induced by ERa, and it is a co-reactivator of ERa; LRP16 promotes MCF-7 cell proliferation and metastasis by modulating the expression level of cyclin Dl and E-cadherin.二, Dependability Between Expression of LRP16 gene and the size orthe metastasis of the cancer in clinical breast cancer samplesObjective: To investigate the Dependability between expression of LRP16 gene and the size or the metastasis of the cancer in clinical breast cancer samples. Methods:collect the clinical tissue samples and the dates of the preliminary diagnosied breast cancer , then immunohistochemical methord was used to detect the expression of LRP16, ER, PR and E-cadherin. Results:The positive rate of LRP16 was higher in the tumours with the size bigger than 2.0cm, the tumours with metastasis of axillary nodes and the tumours with high classification of TNM, but E-cadherin was on the contrary . The positive rate of LRP16 was decreased with the increase of the positive rate of E-cadherin. All the differences had notable statistical significance(P<0.05). Conclusion:The expression of LRP16 in the clinical breast cancer was positively related to the size of the tumor,the metastasis of axillary nodes and the cilincal classification of the tumour, LRP16 can be used as a molecular marker to analysis the prognosis of the breast cancer.Conclusions:1. LRP16 which was a terget gene of estrogen can feedbackly enhance the transcriptional activition induced by ERa, and it is a co-reactivator of ERa.2. LRP16 promotes MCF-7 cell proliferation metastasis by modulating the expression level of cyclin Dl and E-cadherin.3. The expression of LRP16 in the clinical breast cancer was positively related to thesize of the tumor,the metastasis of axillary nodes and the cilincal classification of the tumour, LRP16 can be used as a molecular marker to analysis the prognosis of the breast cancer.