Expressions Of CBX7 And EZH2 In Breast Cancer And Their Clinical Significance

Breast cancer, the most frequently occurring cancer in women of China,According to 2012 GLOBOCAN statistics,nearly 1.7 million women were diagnosed with breast cancer with 522,000 related deaths. Breast cancer is highly heterogeneous in terms of its etiology and pathological characteristics, timely diagnosis and effective treatment is closely related to the prognosis of patients. In addition to the traditional treatment, surgery, chemotherapy, radiotherapy and endocrine therapy treatments,such as molecular targeted therapy has been a research focus in the treatment of breast cancer. Clearly defining the effective molecular biology markers in breast cancer patient can help to develop the corresponding individualized treatment plan.1. Polycomb repressive complexes(PRCs) formed by Polycomb group(Pc G)family members around the chromatin leads to the silence of the target genes from the perspective of epigenetic modifications, and this plays an importent role in the inactivation of X chromosome, the cell cycle control, development and differentiation of cell, proliferation and senescence of cell and the development process of tumor.Chromobox homolog 7(CBX7) gene and Enhancer of zeste homolog(EZH2) both belong to Polycomb group,Participating in the formation of polycomb group complex1 and polycomb group complex 2 to perform their biological functions. It is reported that the abnormal expression level of CBX7 and EZH2 is related to the malignant transformation, development and prognosis of a variety of tumors. At present, related research on CBX7 and EZH2 in breast cancer are rarely reported.ObjectiveTo study the expression level of the CBX7 and EZH2 in breast cancer tissue,benign breast tumor tissue and normal breast tisssue at m RNA and protein level, their correlations and the relations between their expressions with clinical and pathological significance are analyzed,so as to provide reference for clinical diagnosis and treatment of breast cancer.Methods1.Object and grouping: This study set up three groups containing 80 cases,which include human breast cancer tissue(40 cases), benign breast tumor tissue(20cases) and normal breast tissue(20 cases).2.The m RNA expression level of CBX7 and EZH2 in the three groups are detected by RT-PCR method;3.The protein expression level of CBX7 and EZH2 in the three groups are detected by immunohistochemical staining SP method.4. Analyse the correlationship between the two groups in breast cancer from the expression level of gene and protein, and explore the relationships between their expression level and clinical pathological factors, such as the age, menopausal status,tumor size, lymph node metastasis, clinical stage, histological grade and so on.5. Statistical analysis:The SPSS 17.0 was applied to analyze the date.The date was checked respectively by using t-test, analysis of variance(ANOVA)and rank test and Fisher’s exact probabilities, Pearson correlation analysis, With a =0.05 for the test of significance level.Results1.In normal mammary tissue, benign breast tumor tissue and human breast cancer tissue, both CBX7 m RNA expression level and protein expression rate were decreasd in an increasing order, the difference was statistically significant,(P<0.01).2.In normal mammary tissue, benign breast tumor tissue and human breast cancer tissue, both EZH2 m RNA expression level and protein expression rate were increasd in an increasing order, and all the differences reached statistical significance(P<0.01).3. both the m RNA and the protein expression level between CBX7 and EZH2 in breast cancer tissue exhibited a significant negative correlation( r=-0.414,P=0.008;r=-0.794,P=0.015).4.Both m RNA and protein expression level of CBX7 and EZH2 were significantly related to lymph node metastasis and clinical stage(all P<0.05), but not associated with the age, menstrual status, tumor size and histologic classification of the patient(all P>0.05).Conclusions1. The low-expression of CBX7 and the overexpression of EZH2 in human breast cancer tissue may be involved in the progress of malignant transformation of human breast cancer;2. The jiont detection of the 2 indictors of CBX7 and EZH2 in human breast cancer tissue may contribute to cancer diagnosis and treatment, they also could provide a reference to judge the prognosis of breast cancer patients.