The Roles Of MMP-9、ALDH1and BRMS1in Invasion And Metasatasis Of Breast Cancer Cells

Background and Objective:Breast cancer is one of the most common form of cancer diagnosed in women. According to statistics, the proportion of the incidence of breast cancer is7%-10%among systemic all kinds of malignant tumors, threating seriously to the physical mental health of women. Currently, a number of studies have demonstrated thattumor is a stem cell disease. Stem cell possessing characteristics of both self-renewal and hierarchical differentiation is original from normal tissue, while cancer stem cell having the similarity properties is derived from cancers. Tumor origin for stem cell with the capacity of tumorigenicity is abnormal tissue. Metastasis remains the most direct cause of mortality in breast cancer patients.As an important member of matrix metalloproteinases protein family, MMP-9(matrix metalloproteinase9) capable of degradation of most extracellular matrix components to result in the tendency of cancer cell invasion and metasatasis,are expressed in many tumors. ALDH1(aldehye dehydrogenase1) expressed in the early stage of stem cell, with the main function of catalyzing acetaldehyde into acetic acid,and cells with positive ALDH1expression possess tumor stem-like characteristicmay differentiate into glandular epithelium and myoepithelium of breast tissue andhave potential of self-renewal and differentiation. Now, ALDH1has been a putativemaker of breast cancer stem cell and high expression in breast cancer demonstrates unfavourable prognosis of breast cancer via some studies. BRMS1(breast cancermetastasis supressor1) can prominently inhibite the matesatic capacity of breast cancer cells and been involved in the regulation of invasion and metasatasis in manykinds of malignant tumors. Howere, it play an important role in tumor cell proliferation.This study via the investigating of the expression and relationship of MMP-9, ALDH1and BRMS1, analyses the discrepancy in metastatic potential between breast cancer stem cell population and non-stem cell population.Methods:Using serum-free culture medium with cytokine to culture breast cancer MCF-7cells line. Sorting CD44+/CD24cells by immuno magnetic beads. Detecting thecapacity of migration and invasion in both breast cancer stem cell population andnon-stem cell population by Transwell invasion assay. Investigating the expression levels of MMP-9, ALDH1and BRMS1via western blot. The expression of MMP-9,ALDH1and BRMS1examined by immunohistochemical technique in40cases of breast cancer, and20cases of them have been lymph node metastasis.Results:1. Mammosphere culture of breast cancer MCF-7cells line can enrich for breast cancer stem cells.2. The expression of ALDH1in cancer stem cell population is higher than non-stem cell population, found by the identification of immunofluorescence, after immunomagnetic beads sorting.3. Tumor cell migration and invasion experiment shows that the stronger capacities of migration and invasion in cancer stem cell population in comparison withnon-stem cell population.4. By the analysis of western blot, the consequence of the increased expression of MMP-9, ALDH1and decreased expression of BRMS1is significant(P<0.05)in contrast with non-stem cell population.5. Via immunohistochemistry, the expression of MMP-9and ALDH1in lymph node metastasis group are significantly higher than that in no lymph node metastasis group(P<0.05),and the expression of BRMS1in lymph node metastasis groupis lower than that in no lymph node metastasis group(P<0.05).Conclusion:1. Immunomagnetic beads sorting is a simple and viable technique. breast cancer MCF-7cells line is defined by CD44+/CD24-.2. Selective CD44+/CD24-population and non-stem cell population show a distinct metastatic abilities, that CD44+/CD24-population is obviously higher than non-stem cell population after sorting.3. The increased expression of MMP-9, ALDH1and decreased expression ofBRMS1in CD44+/CD24-population provide evidence that the metastatic ablity of CD44+/CD24-population is obviously higher than non-stem cell population.4. The expression of ALDH1is in positive correlation with MMP-9, and in negative correlation with BRMS1. In addition, the expression of MMP-9is negatively correlated with BRMS1. These datas demonstrate that breast cancer stem cells are involved in the metastatic process.