CONTROL OF RECEPTOR NEGATIVE BREAST CANCER GROWTH

雌激素通过调节一部分乳腺癌的生长， 雌激素受体（ER）介导的机制。 失去了急诊室， 与雌激素（E2）调节的丧失和对 抗雌激素治疗 由于没有有效的治疗干预， 可用于治疗ER阴性患者的新举措至关重要 开发新的治疗策略 一种方法是， 重新激活ER基因或开发有针对性的“基因疗法”， 重新引入ER的组成性产生。 我们的战略目标是 确定ER是否可以重新控制 受体阴性乳腺癌细胞。 我们是第一个 用正义和反义核酸转染乳腺癌细胞株MDA-MB-231 突变体（在AA 400处缬氨酸取代甘氨酸）和野生型的cDNA 儿 8种不同的克隆细胞系，组成性产生ER， 通过多顺反子产生氨基糖苷类 磷酸转移酶，其在含有G418的培养基中赋予抗性。 ER是功能性的，可以激活维生素ERETK-CAT，然而野生型 转染子的敏感性大约是突变体的20倍 转染子 通过全细胞摄取（3 HE-2）测定ER水平 在MCF-7乳腺癌细胞的范围内（300-520 fmole/mg蛋白质 (500 fmole/mg蛋白质）。 有趣的是，E2抑制了所有 以浓度相关的方式转染。 述抑制是 被纯抗雌激素ICI 164384阻断 相反， 三苯乙烯4羟基他莫昔芬（40 HT）是一种 激动剂/拮抗剂，但雌激素激动剂 在突变的转染子中。 该提案的目的是 表征我们目前的细胞周期动力学和细胞生物学， 并确定增加转染子的作用。 其他乳腺癌细胞系中的受体数量。 结肠癌细胞 HT-29细胞将被ER转染，以扩大我们对其他细胞的发现。 以前不受雌激素调节的靶器官。 此外，我们还有 我一直对突变体40 HT的药理学改变很感兴趣， 受体，我们将建立抗雌激素药物耐药模型 基于配体受体和激素反应的改变 元素 有证据表明E2对ER的抑制作用 转染的受体阴性细胞是普遍的，因此这些研究将 为寻求新的治疗方法提供了第一个可靠的机制证据， 乳腺癌的治疗方法 在未来，药理学家不仅可以 改变配体要求，但也能够靶向或反应性 静止受体作为癌症的新的一般治疗策略。

Estrogen regulates the growth of a proportion of breast cancers through an estrogen receptor (ER) mediated mechanism. Loss of the ER is associated with a loss of estrogen (E2) regulation and a resistance to antiestrogen therapy. Since no effective therapeutic intervention is available to treat the ER negative patient new initiatives are essential to develop a new treatment strategy. One approach would be either to reactivate the ER gene or to develop a targeted "gene therapy" to re-introduce constitutive production of ER. Our strategic goal is to determine whether the ER could reassert control over the growth of receptor negative breast cancer cells. We are the first group to transfect a breast cancer cell line (MDA-MB-231) with sense and antisense cDNA for both mutant (valine replacing glycine at AA400) and wild type ER. The 8 different cloned cell lines, that constitutively produce ER, were selected by polycistronic production of mRNA for aminoglycoside phosphotransferase which confers resistance in media containing G418. The ER is functional and can activate vit ERETK-CAT however the wild type transfectant is approximately 20 times more sensitive that the mutant transfectant. The ER levels, determined by whole cell uptake of (3 HE-2) are in the range (300-520 fmole/mg protein) of MCF-7 breast cancer cells (500 fmole/mg protein). Interestingly enough E2 inhibits growth of all the transfectants in a concentration related manner. The inhibition is blocked by the pure antiestrogen ICI 164,384. In contrast an analog of the triphenylethylene 4 hydroxytamoxifen (40HT) is a partial agonist/antagonist in the wild type transfectants but an estrogen agonist in the mutant transfectants. The aims of the proposal are to characterize the cell cycle kinetics and cell biology of our current and additional transfectants and to determine the effect of increasing the receptor number in other breast cancer cell lines. Colon cancer cell line HT-29 will be transfected with ER to broaden our finding to other target organs not previously regulated by estrogen. Additionally we have been intrigued by the alteration in pharmacology of 40HT with the mutant receptor; we will establish a model for antiestrogen drug resistance based on alterations in the ligand, receptor and hormone response element. There is evidence that the inhibitory effect of E2 on ER transfected receptor negative cells is universal so these studies will provide the first solid mechanistic evidence to pursue a new therapeutic approach to breast cancer. In the future the pharmacologist may not only alter the ligand requirements but also be able to target or reactive quiescent receptors as a new general therapeutic strategy for cancer.