Biology of Breast Cancers Arising in Older Women

描述(申请人提供)：最近对近4,000个具有多个预后和预测性生物标志物特征的原发乳腺肿瘤的分析支持乳腺癌生物学与年龄相关的基本前提。虽然反映遗传不稳定和肿瘤生长的乳腺癌生物标志物以及生长因子和性类固醇的受体随患者年龄的变化而显著变化，但其他反映肿瘤血管生成、侵袭和蛋白分解潜力的生物标志物与年龄无关，这对当前的癌症衰老假说提出了质疑。在已知的与年龄相关的乳腺癌生物标志物中，有些(如P53阳性、凋亡指数)在50岁后变化最大，另一些(肿瘤细胞增殖指数)在60岁之前变化最大，而另一些(ErbB2、EGFR、ER)随着年龄的增长几乎是连续变化的。值得注意的是，肿瘤雌激素受体(ER)过度表达随年龄的显著增加并未伴随ER诱导基因表达的类似变化(例如PR、PS2、BCl2)，而与氧化应激激活信号增强(P-ERK5)和转录因子功能障碍(Sp1 DNA结合缺失)相关，这支持了我们基础乳腺癌和衰老的两个推论：i)年龄影响乳腺癌生物学，甚至在组织学上相似的ER阳性和结节阴性乳腺癌中也是如此；ii)与氧化应激和衰老相关的蛋白质结构和功能改变似乎是ER阳性乳腺癌的临床和生物学区别亚类。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264例冷冻保存的ER阳性结节阴性导管癌患者的核酸(DNA、RNA)和蛋白质提取物，这些患者发生在老年(大于70岁)和年轻(低于40岁)患者中，这些年龄分组的病例平衡了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记物。由于老年和年轻ER阳性肿瘤预计会使用不同的P53依赖和P53非依赖机制来实现生长失调，因此将使用CGH微阵列、基于PCR的微测序和甲基化状态检测来记录与较高的肿瘤增殖率相关的p21WAF1和p14ARF/p161NK4基因座的染色体获得/丢失、P53突变和表观遗传沉默缺陷的程度和类型，并区分老年和年轻患者。由于ER阳性肿瘤的亚组随着年龄的增加而不同，并与不同的临床结果相关，RNA表达微阵列将用于识别特定的转录谱，这些转录组聚集在年龄定义的肿瘤组内和之间，具有较高的肿瘤增殖率。最后，从这些肿瘤组以及氧化应激诱导的乳腺癌细胞系模型中提取的蛋白质将被用来证实，定义老年患者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(P-ERK5，p66Shc)的增强作用，细胞内蛋白质损伤(碳质含量)，以及Sp1DNA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记物，这些标记物可用于定制针对年龄的治疗方法，并提高我们对衰老、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.