The Expression And Significance Of SBP 1 In Breast Cancer

Backgrounds and Objective: Breast cancer is one of the most common malignant neoplasms and the main cause of death in women. There are about 1.2 million new cases of breast cancer each year in the world, and about 250,000 women die of breast cancer annually. The incidence of breast cancer is lower in China. With the westernization of lifestyle in the recent years, however, the incidence of breast cancer in China has shown an obvious upward trend, and the annual rate of increase of breast cancer in China is about 1-2% higher than that in Europe and the United States. During the two decades from 1982 to 2001, the incidence of breast cancer in Beijing increased by 91%. An average annual growth rate reached 4.6%, higher than the global average annual increasing rate of 2%. Breast cancer in urban women has become the most common malignant tumour after lung cancer, and its mortality rate is also rising. Selenium binding protein1 (SBP1) is one of selenium-binding proteins. SBP1 gene is located at chromosome 1q21-22. Studies have shown that supplementation of dietary selenium results in an increase of SBP1 expression which helps enhance the anti-cancer capability of the body. Decreased SBP1 expression has been observed in many malignant tumours, suggesting that SBP1 level may be able to predict the prognosis in patients with malignant tumours. Our study was designed to examine the following three aspects: 1) the expressions of SBP1 in benign breast lesions (breast proliferation) and breast cancers by immunohistochemistry and western blot, 2) the expression of caspase-3 in breast cancers by immunohistochemistry, and 3) the significance of SBP 1 in breast cancer and correlation between SBP1 and caspase-3 in breast cancer.Method: The expression of SBP1 in benign breast lesion (20 cases) and breast cancer (79 cases), and the expression of caspase-3 in breast cancer (79 cases) were detected by immunohistochemistry method. The expression of SBP1 in benign breast lesion (8 cases) and breast cancer (12 cases) was detected by western blot. We assessed the relationship between SBP1 and clinicopathological characteristics in breast cancer, and assessed the correlation between SBP1 and caspase-3 in breast cancer.Results:1 By immunohistochemistry. SBP1 was detected in both the nucleus and cytoplasm of tumor cells. Higher expression of SBP1 was seen in benign breast lesions (100%) than in breast cancer (83.5%) (P<0.05). By Western blot, the levels of SBP1 in benign breast lesions were higher than that in breast cancers (P<0.05). 2 In breast cancers, the expression of SBP1 was not related to the patient age or the histological grade of the tumor (P>0.05); however, the expression of SBP1 was related to the size of tumour, the lymph nodes status, and the TNM clinical staging (P<0.05).3 Univariate survival analysis of 79 breast cancer cases demonstrated that survival was related to the lymph nodes status, TNM clinical staging, histological grade and the expressions of SBP1. The difference was significant (P<0.05). By multivariate survival analysis, TNM clinical staging (RR:1.891) and the expression of SBP1(RR:0.183)were associated with prognosis of breast cancer (P<0.05).4 The expression of SBP1 in breast cancer was positively correlated with expression of caspase-3 (r = 0.476, p<0.001).Conclusion:1 The difference between the expression of SBP1 in benign breast lesions and that in breast cancer was statistically significant. The expression of SBP1 in breast cancers was not related to the age of the patients or the histological grade of the tumor, but it was associated with the size of the tumour, the lymph node status, and the TNM clinical stage.2 The expression of SBP1 was positively correlated with the expression of caspase-3 in breast cancers.3 Multivariate survival analysis by Cox's proportional hazards regression model showed that TNM clinical staging and the expression of SBP1 were significant prognostic factors in breast cancers. Higher expression of SBP1 correlated with better prognosis in patients with breast cancers.4 SBP1 could be recommended to be used as one of the markers for clinical diagnosis and prognosis assessment in breast cancers.