Biology of Breast Cancers Arising in Older Women

描述（由申请人提供）：最近对近4，000例以多种预后和预测生物标志物为特征的原发性乳腺肿瘤的分析支持乳腺癌生物学具有年龄依赖性的基本前提。虽然反映遗传不稳定性和肿瘤生长以及生长因子和性类固醇受体的乳腺癌生物标志物随患者年龄而显着变化，但反映肿瘤血管生成，侵袭性和蛋白水解潜力的其他生物标志物显示无年龄相关性，这对当前的癌症衰老假说提出了质疑。在已知的年龄依赖性乳腺癌生物标志物中，一些（例如p53阳性、凋亡指数）在50岁之后表现出它们的大部分变化，其他（肿瘤细胞增殖指数）在60岁之前表现出它们的大部分变化，而其他（ErbB 2、EGFR、ER）随着年龄的增加几乎连续变化。值得注意的是，肿瘤雌激素受体（ER）过表达的显著年龄依赖性升高并不伴随着ER诱导基因表达的可比变化。（例如PR、pS2、Bcl 2）并与增强的氧化应激激活信号传导（P-Erk 5）和转录因子功能障碍相关（Sp1 DNA结合的丧失），支持我们基本乳腺癌和衰老前提的两个推论：i）年龄影响乳腺癌生物学，甚至在组织学上相似的ER阳性、淋巴结阴性乳腺癌中也是如此，以及ii）与氧化应激和衰老相关的蛋白质结构和功能改变似乎在临床上和生物学上区分ER阳性乳腺癌的子集。为了从机制上区分与衰老相关的ER阳性乳腺癌亚群，我们将评估来自老年（大于70岁）与年轻（小于40岁）患者中多达264例冷冻库ER阳性淋巴结阴性导管癌的核酸（DNA，RNA）和蛋白质提取物，这些年龄分组的病例与已知的风险因素和与乳腺癌发病率和生物学相关的生物标志物平衡。由于老年和年轻ER阳性肿瘤预期使用不同的p53依赖性和p53非依赖性机制来进行生长失调，因此将使用CGH微阵列、基于PCR的微测序和甲基化状态测定来记录染色体获得/丢失、p53突变、p21 WAF 1和p14 ARF/p161 NK 4基因座的表观遗传沉默缺陷与较高的肿瘤增殖率相关，并区分老年与年轻病例。由于ER阳性肿瘤的亚组随年龄增加而不同，并且与不同的临床结果相关，因此RNA表达微阵列将用于鉴定在年龄定义的肿瘤组内和之间具有较高肿瘤增殖率的特定转录谱聚类。最后，将使用来自这些相同肿瘤组以及来自氧化应激诱导的乳腺癌细胞系模型的蛋白质提取物来确认定义老年患者中产生的ER阳性乳腺癌生物学的关键差异包括肿瘤促进和氧化应激相关细胞信号传导的增强作用（P-Erk 5，p66 Shc），细胞内蛋白质损伤（碳含量），以及Sp1 DNA结合和ER/Sp1驱动的基因表达的丧失。这些DNA、RNA和蛋白质研究有望确定新的乳腺癌生物标志物，可用于定制年龄特异性疗法，并提高我们对受衰老、氧化应激和恶性转化影响的关键亚细胞机制的理解。

DESCRIPTION (provided by applicant): Recent analyses of nearly 4,000 primary breast tumors characterized by multiple prognostic and predictive biomarkers support the basic premise that breast cancer biology is age-dependent. While breast cancer biomarkers reflecting genetic instability and tumor growth as well as receptors for growth factors and sex steroids vary significantly with patient age, others reflecting tumor angiogenic, invasive and proteolytic potential show no age association, calling into question current cancer-aging hypotheses. Among known age-dependent breast cancer biomarkers some (e.g. p53- positivity, apoptotic index) exhibit most of their variation after age 50, others (tumor cell proliferative indices) show most of their variation before age 60, while others (ErbB2, EGFR, ER) change almost continuously with increasing age. Notably, the marked age-dependent rise in tumor estrogen receptor (ER) overexpression is unaccompanied by comparable changes in ER-inducible gene expression (e.g. PR, pS2, Bcl2) and associated with enhanced oxidant stress-activated signaling (P-Erk5) and transcription factor dysfunction (loss of Sp1 DNA-binding), supporting two corollaries to our fundamental breast cancer and aging premise: i) age affects breast cancer biology even among histologically similar ER-positive, node-negative breast cancers, and ii) altered protein structure and function linked to oxidative stress and aging appear to clinically and biologically distinguish subsets of ER-positive breast cancers. To mechanistically distinguish ER-positive breast cancer subsets associated with aging, we will evaluate nucleic acid (DNA, RNA) and protein extracts from up to 264 cryobanked ER-positive node-negative ductal cancers arising in old (greater than age 70) vs. young (less than age 40) patients, with these age-grouped cases balanced for known risk factors and biomarkers linked to breast cancer incidence and biology. Since old and young ER-positive tumors are expected to use different p53-dependent and p53-independent mechanisms for growth dysregulation, CGH microarrays, PCR-based microsequencing and methylation status determinations will be used to document the extent and type of chromosomal gains/losses, p53 mutations, and epigenetic silencing defects in p21WAF1 and p14ARF/p161NK4 loci associated with higher tumor proliferative rates and distinguishing old vs. young cases. Since subgroups of ER-positive tumors increase differently with age and are associated with different clinical outcomes, RNA expression microarrays will be used to identify specific transcript profiles clustering with higher tumor proliferative rates within and between the age-defined tumor groups. Lastly, protein extracts from these same tumor groups, as well as from oxidant stress-induced breast cancer cell line models, will be used to confirm that critical differences defining the biology of ER-positive breast cancers arising in older patients include the enhanced role of tumor-promoting and oxidant stress-associated cell signaling (P-Erk5, p66Shc), intracellular protein damage (carbony content), and loss of Sp1 DNA-binding and ER/Sp1-driven gene expression. These DNA, RNA and protein studies are expected to identify new breast cancer biomarkers that may be used to tailor age-specific therapeutics and improve our understanding of critical subcellular mechanisms affected by aging, oxidative stress and malignant transformation.