Microarray-Based Gene Expression Files Related To Breast Cancer

BackgroundBreast cancer has became one of the major malignant diseases which threaten women'health seriously in the worldwild. Since 1980s, the incidence of breast cancer has showed an upward trend with annual increasing rate of 2%～3% in the world. This phenomenon is worse especially in the developing countries than the developed countries. Data has shown that the number of new cases of breast cancer in China has increased by 38.5% while the death number of breast cancer has increased by 37.1% from 2000 to 2005. Currently, the oncogenesis of breast cancer is not very clear, so there are still a lot of confusion in the early detection and treatment of breast cancer. Any oncogenesis is a very complicated biological process. For an individual, the cells of almost the whole body have the same genetic material DNA, why they (including the tumor cells) have different phenotypes? Data show that the selective expression of genome decides the phenotype of different cells. This indicates that the abnormal change of genetic expression is the foundation by which process the normal cell change into tumor cell. All tumors originate from normal tissues. Tumor cells are the cells which lose the ability of aggregation and constituting the normal tissues. RNA is the connection of DNA and protein. By analyzing the difference of RNA levels between different tissues, we can find some theoretic clue for the further study of gene/protein involved in the ontogenesis of some diseases. This is also a good way to find some related genes or protein in some diseases. So comparing breast cancer and normal breast tissue by microarray to find diffenently expressed genes and to do further study will do some help in clearing and definiting the oncogenesis of breast cancer. This study is aimed to explore the differently expressed genes between breast cancer and normal breast tissue, can provide the evidence of the related genes/proteins to breast cancer'development.ObjectiveExplore the differently expressed genes between breast cancer and normal breast tissue, explore the differently expressed genes between breast cancer and benign breast disease tissue, to provide some guideline for the study of oncogenesis of breast cancer development.MethodsIn this study,21 breast tissues (7 are breast cancer tissues,7 are their corresponding normal breast tissues,7 are benign breast disease tissues) were detected by microarray. Then we used real-time PCR to verify the results of microarray. We used GeneOntology (GO) system to classify the differently expressed genes.Results1. Differently expressed genesThere are 344 differently expressed genes between breast cancer tissue and corresponding normal breast tissues, including 273up-regulated and 71 down-regulated genes. There are 27 genes related to cell proliferation, while 21 up-regulated and 6 down-regulated. Fifteen genes are related to cell adhesion, while 5 up-regulated and 10 down-regulated. Twnety three genes are related to cell apoptosis, while 20 up-regulated and 3 down-regulated.There are 235 differently expressed genes between breast cancer tissue and corresponding normal breast tissues, including 140 up-regulated and 95 down-regulated genes. There are 10 genes related to cell proliferation, while 8 up-regulated and 2 down-regulated. Twelve genes are related to cell adhesion, while 7 up-regulated and 5 down-regulated. Elevne genes are related to cell apoptosis, while 10 up-regulated and 1 down-regulated.2. Cluster analysis of the two kinds of samplesUsing cluster 3.0 to analyze the data of microarray experiment, the 3 kinds of samples can not be divided to 3 groups directly. To analyze the data of microarray experiment of breast cancer and correspongding normal breast tissue, the result is the same.ConclusionThere are obviously difference in the level of mRNA between breast cancer and normal breast tissue. The differented expressed genes in this study refered to some important biological process in the development of cancer, such as cell proliferation, cell adhesion and cell apoptosis. These genes may have some relationship with breast cancer. We still need more study to verify the function of these genes in ontogenesis of breast cancer. By this study, we can limit the related genes for breast cancer from mass of gene information. We can study the related function between these genes, find some candidate genes to study their change in gene or protein in the development of breast cancer.