Vitamin K: Body Pools and Function in Breast Cancer

项目摘要/摘要 这项建议侧重于维生素K的两种主要饮食形式对乳腺癌的不同影响。K 维生素是伽马-谷氨酰羧基酶的辅助因子，它在翻译后引入γ- 将羧基谷氨酸残基转化为蛋白质。尽管已知的17个γ-羧化蛋白中的大多数在 凝血和骨稳态，GGCX在大多数组织(包括乳腺)中的存在表明 维生素K的更广泛的生理作用。我们已经证明，三阴性乳腺癌 (TNBC)细胞株表达GGCX并产生γ-羧化蛋白，以响应维生素K1(叶醌)， 主要的饮食形式。在TNBC细胞中，K1处理丰富了干细胞标志物乙醛脱氢酶 1(ALDH1)，并促进乳房层的形成。这些数据表明，K1维持GGXC介导的γ- 羧化作用驱动侵袭性乳腺癌表型。通过对基因组癌症数据集的分析，我们 发现约25%的乳腺肿瘤表达GGCX和其所需的维生素K氧化还原酶(VKOR)基因 活动。与那些肿瘤不表达这些基因的患者相比，患有这种肿瘤的患者的存活率更低。 很高的水平。患有这一亚型肿瘤的患者可能会接受限制K1可获得性和/或 抑制GGCX。令人惊讶的是，我们发现另一种自然存在的形式--维生素K2(菜籽酮-4) 在饮食中，不会刺激γ-羧化或TnBC细胞的干细胞表型，而是强烈抑制 细胞生长、迁移和能量代谢。这些具有挑衅性的数据表明，K1和K2对 对乳腺癌细胞的影响，K1促进和K2抑制侵袭性表型。我们还发现 维生素K2生物合成酶UbiA丙基转移酶结构域1(UBIAD1)的表达 在TNBC中检测不到，这表明维生素K的细胞处理方式发生了变化。在目标1中，我们将剖析其影响 在体外，评估UBIAD1的作用并进行喂养研究以测量K1的积累 和K2在TNBC移植瘤和宿主乳腺中与肿瘤生长的关系。在目标2中，我们将确定 肿瘤细胞GGCX基因缺失是否影响γ-羧化蛋白合成和侵袭性 体外和体内的表型。AIM 3将确定相关的γ-羧化GGCX底物蛋白 K1的影响。我们预计GGCX活性高而UBIAD1低的肿瘤将被刺激生长 由高K1和高K2抑制。这些发现将确定GGCX是一种癌基因 维生素K途径作为晚期乳腺癌患者亚群的治疗靶点。

PROJECT SUMMARY/ABSTRACT This proposal focuses on the divergent effects of the two major dietary forms of vitamin K on breast cancer. K vitamins act as cofactors for gamma-glutamyl carboxylase (GGCX), which post-translationally introduces γ- carboxyglutamate residues into proteins. Although most of the 17 known γ-carboxylated proteins function in coagulation and bone homeostasis, the presence of GGCX in most tissues (including mammary gland) suggests more extensive physiological roles for vitamin K. We have demonstrated that triple negative breast cancer (TNBC) cell lines express GGCX and produce γ-carboxylated proteins in response to vitamin K1 (phylloquinone), the major dietary form. In TNBC cells, K1 treatment enriches for the stem cell marker aldehyde dehydrogenase 1 (ALDH1) and promotes mammosphere formation. These data suggest that K1 sustains GGXC mediated γ- carboxylation to drive aggressive breast cancer phenotypes. Through analysis of genomic cancer datasets, we find that ~25% of breast tumors express GGCX and the vitamin K oxidoreductase (VKOR) genes required for its activity. Patients with such tumors have poorer survival than those whose tumors do not express these genes at high levels. Patients with this subtype of tumor would be candidates for therapies that limit K1 availability and/or inhibit GGCX. Surprisingly, we found that vitamin K2 (menaquinone-4), another naturally occurring form present in diet, does not stimulate γ-carboxylation or stem cell phenotypes in TNBC cells, but instead strongly suppresses cell growth, migration and energy metabolism. These provocative data indicate that K1 and K2 exert distinct effects on breast cancer cells, with K1 promoting and K2 suppressing aggressive phenotypes. We also found that expression of the vitamin K2 biosynthesis enzyme UbiA Prenyltransferase Domain Containing 1 (UBIAD1) is undetectable in TNBC, suggesting altered cellular handling of vitamin K. In Aim 1 we will dissect the effects of K1 and K2 in vitro, evaluate the role of UBIAD1 and conduct feeding studies to measure accumulation of K1 and K2 in TNBC xenografts and host mammary gland in relation to tumor growth. In Aim 2 we will determine whether deletion of GGCX from TNBC cells impacts γ-carboxylated protein synthesis and aggressive phenotypes in vitro and in vivo. Aim 3 will identify relevant γ-carboxylated GGCX substrate proteins that mediate the effects of K1. We anticipate that growth of tumors with high GGCX activity and low UBIAD1 will be stimulated by high dietary K1 and inhibited by high dietary K2. These findings would identify GGCX as an oncogene and the vitamin K pathway as a therapeutic target in a subset of patients with advanced breast cancer.