Compositional and Functional Analysis of Breast Density in Human Tissue

乳腺摄影乳腺密度是乳腺癌风险的一个强有力的预测因素。有放射性致密区的女性 乳腺癌的风险增加3至5倍， 很少或没有放射密度区的女性。据估计，近1/3的乳腺癌发病率是 这是由于调节乳腺密度的生物学变量（遗传和环境）。鉴于这种 乳腺密度和乳腺癌风险之间存在很强的相关性，令人惊讶的是， 关于致密乳腺组织的特征或起源。 我们假设基质和上皮之间的分子相互作用代表了 乳腺组织内发生的第一个变化允许恶性转化， 作为早期乳腺癌的预测指标。我们认为，基质增加的特征 在乳腺X线摄影致密组织中的细胞外基质（ECM）和分子标记物中观察到重塑， 乳房是“激活的”基质的指示。活化的基质（AS）类似于 正常的非病理过程，如形态发生和伤口愈合，也可以在 病理状态如结缔组织增生。虽然正常的基质-上皮相互作用积极抑制 在肿瘤前表型中，活化的基质可以成为癌症进展的积极参与者。我们 假设高乳腺密度和乳腺癌增加之间的机械联系 风险在于导致乳腺密度增加的信号转导途径， 同时促进邻近上皮中起始细胞的恶性进展。这 该提案将研究表型，分子和功能差异的几个方面， 从具有高或低乳房摄影密度的个体分离的乳腺成纤维细胞和上皮细胞 患或未患乳腺癌的人。这些组织的组织学和分子学评价将 提供了新的标志物，确定乳腺密度增加和癌症风险增加。在项目2中，我们 1)确定高和低浓度乳腺癌患者乳腺组织的细胞和组织学组成， 乳房摄影密度腺体的三维重建（3D），连接到BioSig 数据库，将整合这种形态学数据与分子数据。(2)使用cDNA微阵列，我们将 将来自具有高和低乳腺摄影密度的组织的表达谱相互比较（a） 和（B）来自已在远处发生癌症的个体的匹配组织。这些标记 可用于项目3，通过免疫染色评估石蜡保存的良性乳腺活检组织， 乳腺癌的发病风险。具体目标3体内和体外重组实验将 提供了深入了解细胞组合，产生增加乳腺密度和分子标记 与乳腺癌风险增加有关。(3)最后，我们将确定的功能表型 从具有高和低乳腺摄影密度的人乳腺组织获得的成纤维细胞。我们有 发现来自高乳腺摄影密度组织的成纤维细胞保留了 生物学相关的途径，如IGF轴。这些成纤维细胞已被证明 当置于鼠重组模型中时促进肿瘤进展。拟议的研究将 确定成纤维细胞增强肿瘤发生表型的分子基础。

Mammographic breast density is a strong predictor of breast cancer risk. Women with radiodense areas covering greater than 50% of the tissue area have a 3 to 5 fold increase in risk for breast cancer compared with women with little or no radiodense area. It is estimated that almost 1/3 of breast cancer incidence is due to biological variables (both genetic and environmental) that modulate breast density. Given this strong correlation between breast density and risk for breast cancer, it is surprising that so little is known about the character or origin of dense breast tissue. We hypothesize that the molecular interactions between stroma and epithelium represent some of the very first changes that occur within breast tissue allowing malignant transformation and may therefore serve as a predictor of breast cancer in its earliest stages. We propose that features of increased stromal remodeling noted in the extracellular matrix (ECM) and molecular markers in mammographically dense breasts are indicative of an 'activated' stroma. Activated stroma (AS) is similar to stroma formed during normal, non-pathological processes such as morphogenesis and wound healing, and can also be found in pathological states such as desmoplasia. While normal stromal-epithelial interactions actively suppress preneoplastic phenotypes, activated stroma can become an active participant in cancer progression. We hypothesize that the mechanistic links between high breast density and increased breast cancer risk lie in the signal transduction pathways that lead to increased breast density and concomitantly promote malignant progression in initiated cells in the adjacent epithelium. This proposal will examine several aspects of the phenotypic, molecular and functional differences of mammary fibroblasts and epithelial cells isolated from individuals with high or low mammographic density that have or have not developed breast cancer. Histologic and molecular evaluation of these tissues will provide novel markers that define increased breast density and increased cancer risk. In Project 2, we will 1) Determine the cellular and histological composition of human breast tissues with high and low mammographic density. A three-dimensional reconstruction (3D) of the gland, linked to the BioSig database, will integrate this morphologic data with molecular data. (2) Using cDNA microarrays, we will compare expression profiles from tissues with high and low mammographic densities (a) to each other and (b) to matched tissues from individuals that have developed cancer at a distant site. These markers can be used in Project 3 to evaluate paraffin-preserved benign breast biopsy tissue by immunostains for association of risk for breast cancer. In Specific Aim 3 In vivo and in vitro recombinant experiments will provide insights into the cell combinations that generate increased breast density and molecular markers associated with increased breast cancer risk. (3) Finally we will determine the functional phenotype of fibroblast cells obtained from human breast tissues with high and low mammographic density. We have found that fibroblasts from tissue with high mammographic density retain differential expression of biologically relevant pathways such as the IGF-axis. These fibroblasts have been demonstrated to facilitate tumor progression when placed in a murine recombinant model. The proposed studies will determine the molecular basis for fibroblast enhancement of tumorigenic phenotypes.