KCNK9 Imprinting in Breast Cancer Progression and Metastasis

描述（由申请人提供）：三阴性乳腺癌[ER/PR-/-，HER 2/neu wt，EGFR+]常发生于年轻女性，预后不良。虽然并非所有三阴性乳腺癌都是致命的，但在绝经前非洲裔美国妇女中，三阴性乳腺癌的5年死亡率为86%。由于许多三阴性乳腺癌在诊断时对化疗具有耐药性，因此非常需要早期检测。在这里，我们的目标是研究一种新的信号通路，有望早期检测三阴性乳腺癌。TASK 3是一种pH敏感性钾通道蛋白，可调节线粒体膜电位m）。TASK 3的过表达增加m，从而促进抗凋亡和耐缺氧。在初步数据中，我们表明TASK 3在1）化疗耐药转移性三阴性乳腺癌和2）高危非洲裔美国妇女的癌前乳腺疾病中过表达。 KCNK 9（TASK 3基因）受印记调控：印记缺失预测三阴性乳腺癌的化疗耐药性和随后的转移：编码TASK 3蛋白的基因KCNK 9受甲基化印记调控。印迹是一种正常的调控过程，其中基因的一个拷贝被失活，导致单等位基因表达。正常印记的丧失导致功能性二倍体状态和靶基因的过表达。 KCNK 9基因的一个拷贝通常是印记的，使KCNK 9单倍体的正常功能状态（一个基因拷贝表达，一个拷贝不表达）。在初步数据中，我们在KCNK 9启动子中发现了一个差异甲基化区域（DMR），该区域在正常乳腺上皮细胞中被印记，但在原发性化疗耐药三阴性乳腺癌中没有印记。DMR印迹的缺失预测了TASK 3过表达、化疗耐药性和随后的转移。 假设：KCNK 9 DMR甲基化印迹的缺失和缺氧协同促进三阴性乳腺癌中TASK 3的过表达和转移目的1将测试缺氧是否在缺乏KCNK 9 DMR印记的三阴性乳腺癌中转录激活TASK 3。我们将在常氧和低氧条件下对KCNK 9 HRE活性、TASK 3表达、肿瘤生长和转移以及血红蛋白饱和度进行体内多参数分析。目的2将测试正常KCNK 9 DMR印迹的丧失是否促进三阴性乳腺癌的起始、进展和转移。 重要性：成功完成本提案的目标将提高我们识别生物侵袭性转移性三阴性乳腺癌的能力。三阴性乳腺癌在绝经前非洲裔美国妇女中具有高死亡率。我们建立的高风险队列将允许我们快速测试KCNK 9 DMR印记的丢失是否促进化疗抗性转移性三阴性乳腺癌。

DESCRIPTION (provided by applicant): Triple-negative breast cancers [ER/PR-/-, HER2/neu wt, EGFR+] frequently occur in young women and carry a poor prognosis. While not all triple-negative breast cancers are lethal, triple-negative breast cancers have 86% 5-year mortality in pre-menopausal African American women. Since many triple-negative breast cancers are chemotherapy-resistant at diagnosis, there is a great need for early detection. Here we aim to investigate a novel signaling pathway that holds promise for early detection of triple-negative breast cancer.TASK3 is a pH sensitive potassium channel protein that regulates mitochondrial membrane potential m). Overexpression of TASK3 increases m, and thereby promotes apoptosis resistance and tolerance of hypoxia. In Preliminary Data, we show that TASK3 is overexpressed in 1) chemotherapy-resistant metastatic triple-negative breast cancers and 2) premalignant breast disease in high-risk African American women. KCNK9 (TASK3 gene) is regulated by imprinting: loss of imprinting predicts chemotherapy resistance and subsequent metastasis of triple-negative breast cancer: The gene coding for the TASK3 protein, KCNK9, is regulated by methylation imprinting. Imprinting is a normal regulatory process where one copy of the gene is inactivated resulting in mono-allelic gene expression. Loss of normal imprinting results in a functional diploid state and overexpression of the target gene. One copy of the KCNK9 gene is normally imprinted, making the normal functional state of KCNK9 haploid (one gene copy expressed, one copy not expressed). In Preliminary Data, we identified a differentially methylated region (DMR) in the KCNK9 promoter that was imprinted in normal mammary epithelial cells but not in primary chemotherapy-resistant triple-negative breast cancers. Loss of DMR imprinting predicted TASK3 overexpression, chemotherapy-resistance, and subsequent metastasis. Hypothesis: Loss of methylation imprinting of KCNK9 DMR and hypoxia synergistically promote TASK3 overexpression and metastasis in triple-negative breast cancer. Aim 1 will test whether hypoxia transcriptionally activates TASK3 in triple-negative breast cancers that lack imprinting of the KCNK9 DMR. We will perform in vivo multi-parametric analysis of KCNK9 HRE activity, TASK3 expression, tumor growth and metastasis, and hemoglobin saturation in normoxic and hypoxic conditions. Aim 2 will test whether loss of normal KCNK9 DMR imprinting promote initiation, progression, and metastasis of triple-negative breast cancer. Significance: Successful completion of the aims of this proposal will improve our ability to identify biologically aggressive metastatic triple-negative breast cancer. Triple-negative breast cancers have a high mortality in premenopausal African American women. Our established high-risk cohort will allow us to rapidly test whether loss of KCNK9 DMR imprinting promotes chemotherapy-resistant metastatic triple- negative breast cancers.