MOLECULAR VARIANTS & OVEREXPRESSION OF ESTROGEN RECEPTORS IN BREAST CANCER

乳房是雌激素反应组织，大多数乳房肿瘤 看起来至少在一开始是雌激素依赖的。此外， 雌激素受体(ER)不仅在乳腺肿瘤中高表达，而且 即使在早期癌前病变与正常相比 乳腺上皮细胞，因此它可能与进展相关 癌症。我们最近还在几个早期病变中发现了一种独特的 对雌激素过敏的ER突变体。在许多乳腺肿瘤中 我们发现ER剪接变异体的表达增强，特别是 外显子5缺失变异体，即使在没有雌激素和 使他莫昔芬产生抗药性。因此看起来很可能是精神错乱 在ER的表达水平或结构中可能在 乳腺癌的发生和激素的失效 治疗过程中的反应性。 我们现在建议调查ER过度表达是如何在 乳房病变的早期进展，如何出现某些 变异体可能与原乳房的生物学行为有关 肿瘤，特别是他莫昔芬的耐药性，以及是否会进一步ER 改变可能与转移的发生有关。 我们的目标是：91)确定ER升高的分子基础 乳腺增生性病变与乳腺肿瘤的表达比较 通过对启动子的分析，将其与邻近的正常乳腺上皮进行比较 内质网区域和细胞特异性ER反式激活的分析 存在导致不适当激活的因素 ER在这些皮损中的表达。(2)发现表情是否 5号外显子ER缺失突变在原发性乳腺癌中的作用 与临床三苯氧胺耐药有关的三苯氧胺治疗 圣安东尼奥肿瘤库和大型随机分组的患者 瑞典佐剂试验。(3)研究转移瘤的内质网变化 乳腺癌可能与肿瘤进展有关，通过 DNA直接测序和单链构象多态性分析 转移性肿瘤标本。已确定的ER更改将是 使用我们的一系列独特的雌激素诱导的ERE 记者。细胞的迁移、侵袭和转移行为也会 确定在稳定的乳腺癌细胞系中转染人 这些特征与特定内质网改变的表达相关。我们 还将关联从以下来源分离的单个ER变体的水平 转移性乳腺病变的临床转归。 我们已经有了关于发生的重要发现 雌激素受体的变异型及其调控 在临床乳腺癌方面。拟议的工作现在应该清楚地表明 ER在早期乳腺病变中的作用。它还应该表明是否 外显子5截短缺失ER的高水平出现 乳腺癌中的剪接变异与临床上不祥的 他莫昔芬耐药性的发展，并提示哪些ER变种或 突变预示着转移。

The breast is an estrogen responsive tissue, and most breast tumors appear to be, at least initially, estrogen dependent. Furthermore, the estrogen receptor (ER) is overexpressed not only in breast tumors but even in early premalignant breast lesions as compared with normal breast epithelium, so that it may be associated with progression toward cancer. We have also recently found in several early lesions a unique ER mutant which is hypersensitive to estrogen. In many breast tumors we have found enhanced expression of ER splice variants, particularly an exon 5 deletion variant which is active even without estrogen and confers tamoxifen resistance. Thus it seems likely that derangements in the expression level or structure of ER may well play roles both in the development of breast cancer and in the failure of hormone responsiveness during treatment. We now propose to investigate how ER overexpression arises during early progression of breast lesions, how the appearance of certain variants may contribute to the biological behavior of primary breast tumors, particularly tamoxifen resistance, and whether further ER alterations may be associated with the development of metastases. Our Aims are: 91) To determine the molecular basis for elevated ER expression in hyperplastic breast lesion and breast tumors as compared to adjacent normal breast epithelium, by analysis of the promoter region of the ER and by analysis of the cell-specific ER transactivating factors present which are responsible for the inappropriate activation of ER expression in these lesions. (2) To discover whether expression of the truncated exon 5 ER deletion variant in primary breast cancer is associated with clinical tamoxifen resistance, using tamoxifen-treated patients in the San Antonio Tumor Bank and in a large randomized Swedish adjuvant trial. (3) To study ER alterations in metastatic breast cancers which might be associated with tumor progression, by both direct DNA sequencing and SSCP analyses of paired primary and metastatic tumor specimens. Identified ER alterations will be characterized using our series of unique estrogen-inducible ERE reporters. Cell migration, invasion, and metastatic behavior will also be determined in stable breast cancer cell line transfectants to correlate these features with expression of specific ER alterations. We will also correlate levels of individual ER variants isolated from metastatic breast lesions with clinical outcome. We have already made important discoveries on the occurrence of variant forms of the estrogen receptor and regulation of the receptor in clinical breast cancer. The proposed work should now shed light on the role of Er in early breast lesions. It should also indicate whether the appearance of higher levels of the truncated exon 5 deletion ER splice variant in breast cancer is related to the clinically ominous development of tamoxifen resistance, and suggest which ER variants or mutations presage metastasis.