The Clinical Significance Of Rictor In Breast Cancer And The Functional Study In Regulating Angiogenesis

Objective The recurrence and metastasis after treatment is the main reason of death caused by breast cancer,during which angiogenesis plays an important role.Rapamycin insensitive protein complexes(mammalian target of rapamycin complex 2,m TORC2)is a kinase complex formed by m TOR,m LST8,m Sin1,Protor and Rictor(rapamycin insensitive companion of m TOR),involving in the regulation of body cells’ metabolism,growth,proliferation,apoptosis and angiogenesis in cancer tissues,influencing on the proliferation and metastasis of breast cancer cells effectively.Rictor is a skeleton protein of m TORC2,which is essential to the stability of m TORC2,and it is the necessary material for m TORC2 to play the biological function.Rictor protein is highly expressed in many kinds of cancer tissues,including breast cancer,the high expression of Rictor often followed by poor prognosis,and so far,there are few studies focused on the mechanism of influencing prognosis of breast cancer patients.The purpose of this study was to analyze the expression of Rictor in breast cancer tissues,and explore the relationship between Rictor and the clinicopathological parameters as well as prognosis;and to investigate the possible molecular mechanism of Rictor in regulating angiogenesis,in order to provide ideas and new theoretical basis for the treatment of breast cancer.Methods We selected 70 patients with breast invasive ductal carcinoma(invasive ductal carcinoma,IDC)from November 2008 to April 2009 in Tianjin Tumour Hospital randomly.The expression of Rictor,VEGF and vascular marker CD34 in each tissue was detected by immunohistochemical staining method;statistical methods was used to analyze the association between Rictor level with clinicopathological parameters and patients’ prognosis,P < 0.05 was statistically significant.We use RNA interference technology to establish a stable Rictor knockdown breast cell line,the expression level of Rictor,VEGF and CD31 was detected by Western Blotting,and the content of VEGF and MMP-9 in the cell culture medium was detected by Elisa,then we analyzed its possible molecular mechanism.Results 1.The expression of Rictor in invasive ductal carcinoma of breast Immunohistochemical staining results of Rictor revealed that the positive expression of Rictor in 70 IDC of breast tissues was 78.6%.And the negative(-),low expression(+),moderate expression(++)and high expression(+++)rates were 21.4%,10%,28.6% and 40% respectively.2.The relationship between the expression of Rictor in invasive ductal carcinoma of breast and the clinicopathological features Statistical analysis shows that,the expression level of Rictor has a relationship with tumor size(P = 3.7×10-4),axillary lymph node metastasis(P = 0.022),clinical stages(P = 0.005),VEGF(P = 2×10-6)and CD31(P = 6.1×10-7),among with the correlation coefficients of Rictor with VEGF and CD31 were 0.535 and 0.510,respectively.3.The relationship between the expression level of Rictor in IDC of breast and the prognosis The Log-rank test showed that,the tumor size,the number of metastased axillary lymph node,Rictor,VEGF and endocrine therapy may affect patients DFS and OS.However,the Cox Multi-factor analysis showed that the expression of Rictor and the prognosis of patients has no statistical significance.4.Compared with the control groups,the expression of VEGF and CD31 protein were significantly decreased in the stable Rictor-knockdown breast cancer cell line;the secretion of VEGF and MMP-9 was decreased significantly under the same culture condition.Conclusion 1.Rictor positive patients will be with a high rate of axillary lymph node metastasis,and the axillary lymph node positive patients will have a high positive rate of Rictor in cells,it prompted that Rictor may be related to the transfer process in human body of breast cancer patients.2.Rictor protein can influence the DFS and OS of patients effectively,it prompted that Rictor may be an adverse prognostic factors of breast cancer.However,The Cox Multi-factor analysis showed that the expression of Rictor was not related to the prognosis.Therefore,whether Rictor can be used as a prognostic indicator of breast cancer,more clinical data is needed to make it clear.3.Compared with the control group,the expression of VEGF and CD31 was decreased in the stable Rictor-knockdown breast cancer cell line,and the secretion of VEGF and MMP-9 also decreased.It indicated that Rictor can regulate the synthesis and secretion of VEGF 、CD31 and MMP-9 by some corresponding molecular mechanisms,affecte the formation of blood vessels and metastasis of cancer cells.