乳腺癌是一种高度异质性的肿瘤，基因异质性在乳腺癌转移及化疗抵抗中发挥重要作用。申请人前期参与研究的高分辨率定量多色荧光原位杂交技术（QM-FISH），能精确区分不同肿瘤细胞克隆，检测同一肿瘤细胞内30种以上基因的拷贝数变异(CNVs)。我们前期通过对新辅助化疗标本的研究，发现异质性肿瘤细胞克隆在化疗反应方面存在明显差异。初步研究结果提示我们有必要对肿瘤克隆性基因差异表达进行更加细致、深入的研究，开发一种前瞻性分子诊断程序，用于复杂类型乳腺癌患者的精细化分子病理诊断。本项目将从病理形态、蛋白受体表达及基因CNVs异质性的不同层面入手，比较乳腺癌原发灶和转移灶肿瘤细胞的异质性变化，利用计算机软件辅助分析，从复杂多变的分子事件中获取与转移相关的关键基因变化；追踪基因异质性肿瘤克隆在化疗过程中的分子变化，以及对化疗药物的反应性差异，探寻与化疗抵抗相关的基因变化，为临床化疗方案的制定提供理论指导。

Breast cancer is known to be a heterogeneous disease. Genetic heterogeneity plays an important role in tumor metastasis and resistance to chemotherapy. In our previous work, we detected 30 genes copy number variations (CNVs) in the breast cancers with different differentiation using QM-FISH (Qantitative Multicolour Fluorescent In Situ Hybridization) which allows the quantitative determination of genes in each individual cell nucleus, and thus enables the analysis of genetic changes in relation to intro-tumor heterogeneity. By the comparison of the biomarkers status changes prior to and after neoadjuvant chemotherapy (NAC), we found different chemo-response in tumors with clonal variations. Our previous work suggests that it is of great value to explore a prospective procedure for genetically heterogeneous breast cancer patients. In the current project, we will focus on detailed analysis of genetic variation within multiple samples from the same patient, including specimens from primary loci and metastatic loci, NAC samples prior to and after chemotherapy. Using QM-FISH technical approaches, we will search for features predicting metastasis and to identify specific genetic signatures relating to chemotherapy response. Completion of this project will help to predict the risk of metastasis and provide reasonable strategies for breast cancer patients with intro-tumor heterogeneity.