MOLECULAR VARIANTS & OVEREXPRESSION OF ESTROGEN RECEPTORS IN BREAST CANCER

分子变体

• 批准号: 6334930
• 负责人: Suzanne AW Fuqua
• 金额: $ 18.15万
• 依托单位: BAYLOR COLLEGE OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-08-01 至 2001-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6334930
• 关键词: breast neoplasms; cell line; cell migration; clinical research; drug resistance; estrogen receptors; female; gene expression; genetic promoter element; health services research tag; hormone related neoplasm /cancer; human subject; human tissue; immunocytochemistry; mutant; neoplastic process; nucleic acid sequence; paclitaxel; single strand conformation polymorphism; transcription factor; transfection

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.

乳腺是一个雌激素敏感组织，大多数乳腺肿瘤 似乎至少在最初是雌激素依赖性的。 而且 雌激素受体（ER）不仅在乳腺肿瘤中过表达， 即使在早期癌前乳腺病变与正常相比， 乳腺上皮细胞，因此它可能与向 癌 我们最近还在几个早期病变中发现了一种独特的 ER突变体，对雌激素过敏。 在许多乳腺肿瘤中 我们发现ER剪接变异体的表达增强， 外显子5缺失变体，其即使在没有雌激素的情况下也是有活性的， 赋予他莫昔芬抗性。 由此看来， 在ER的表达水平或结构上， 乳腺癌的发展和激素的失败 治疗期间的反应。 我们现在建议研究ER过度表达是如何在 乳腺病变的早期进展，如何出现某些 变异可能有助于原发性乳腺癌的生物学行为， 肿瘤，特别是他莫昔芬耐药性，以及是否进一步ER 这些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 在乳腺增生性病变和乳腺肿瘤中的表达， 通过分析启动子， 区域的ER和通过分析细胞特异性ER反式激活 存在导致不适当激活的因素 ER在这些病变中的表达。 (2)为了发现表达是否 原发性乳腺癌中截短的第5号外显子ER缺失变体的 与临床他莫昔芬耐药相关，使用他莫昔芬治疗 圣安东尼奥肿瘤库和一个大型随机 瑞典辅助试验。 (3)为了研究转移性乳腺癌中ER的改变， 可能与肿瘤进展相关的乳腺癌， 直接DNA测序和SSCP分析配对的主要和 转移性肿瘤标本。 确定的ER改变将 使用我们的一系列独特的雌激素诱导的雌激素受体 记者说 细胞迁移、侵袭和转移行为也将 在稳定的乳腺癌细胞系转染子中测定， 将这些特征与特定ER改变的表达相关联。 我们 也将与分离的个体ER变体的水平相关， 转移性乳腺病变的临床结局。 我们已经有了重要的发现， 雌激素受体的变异形式和受体的调节 乳腺癌的临床表现。 拟议的工作现在应该阐明 ER在早期乳腺病变中的作用。 还应说明是否 出现较高水平的截短外显子5缺失ER 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，并提出哪些ER变体或 突变预示着转移。