YEAST CELL-BASED SCREEN FOR BREAST CANCER THERAPEUTICS

大多数人类乳腺癌表达雌激素受体α(ER+表型)。虽然在这些患者中，大约60%的患者使用他莫昔芬辅助治疗可以减少肿瘤复发并提高存活率，但长期使用总是会导致耐药性。对于40%的激素非依赖性ER+乳腺癌，以及ER+他莫昔芬耐药的转移癌，目前缺乏有效的治疗方法。最近，一种新的激活雌激素受体α(ER)的机制被阐明。研究表明，细胞周期蛋白D1能刺激内质网激活的报告基因的体内转录。Cyclin D1的这种刺激独立于CDK4发生，ER不被磷酸化，更重要的是，报告基因的激活是在没有雌激素的情况下发生的。以往的研究表明，细胞周期蛋白D1在大约50%的乳腺癌中过度表达。因此，细胞周期蛋白D1/ER介导的生长反应基因的表达可能参与了激素非依赖性、ER+乳腺癌和三苯氧胺耐药转移瘤的增殖。因此，抑制细胞周期蛋白D1/ER转录激活基因的化合物可能会阻止这些乳腺癌细胞的增殖。在第一阶段的研究中，将开发报告基因被人细胞周期蛋白D1/ER激活的酿酒酵母菌株。这项技术将在第二阶段的高通量筛查计划中使用。在这种筛查中发现的化合物可能会被开发成治疗激素非依赖性乳腺癌的有效药物。建议的商业应用：乳腺癌是美国女性癌症死亡的第二大原因，也是30-70岁女性癌症死亡的主要原因。在第一阶段研究中开发的技术将在第二阶段用于发现化合物，这些化合物可能对40%以上对目前的内分泌治疗无效的ER+乳腺癌有效。

The majority of human breast cancers express estrogen receptor alpha (ER+ phenotype). Although adjuvant treatment with tamoxifen reduces tumor recurrence and increases survival in approximately 60% of these patients, prolonged use invariably leads to resistance. For the 40% of hormone independent ER+ breast cancers, as well as the ER+ tamoxifen resistant metastases, effective therapeutics are currently lacking. Recently, a novel mechanism of activating estrogen receptor alpha (ER) was elucidated. Cyclin D1 was shown to stimulate the in vivo transcription of reporter genes activated by the ER. This stimulation by cyclin D1 occurred independently of CDK4, the ER was not phosphorylated and, importantly, reporter gene activation occurred in the absence of estrogen. It had previously been well documented that cyclin D1 is overexpressed in approximately 50% of all breast cancers. Therefore, expression of growth response genes mediated by cyclin D1/ER may be involved in the proliferation of hormone independent, ER+ breast cancers and tamoxifen resistant metastases. Compounds which inhibit transcriptional activation of genes by cyclin D1/ER may therefore prevent proliferation of these breast cancer cells. During Phase I research, Saccharomyces cerevisiae yeast strains in which reporter genes are activated by human cyclin D1/ER will be developed. This technology will be utilized in high-throughput screening programs during Phase II. Compounds discovered in such screens may be developed into effective therapeutics for hormone independent breast cancers. PROPOSED COMMERCIAL APPLICATIONS: Breast cancer is the second leading cause of cancer deaths in women in the United States, and the leading cause of cancer deaths in women aged 30 to 70 years. The technology developed during Phase I research will be used in Phase II for discovery of compounds which may be effective therapeutics for the more than 40% of ER+ breast cancers which do not respond to current endocrine therapies.