Vitamin K: Body Pools and Function in Breast Cancer

项目总结/摘要 这项建议的重点是两种主要饮食形式的维生素K对乳腺癌的不同影响。K 维生素作为γ-谷氨酰羧化酶（GGCX）的辅因子，其在转录后引入γ-谷氨酰羧化酶。 羧基谷氨酸残基转化为蛋白质。尽管17种已知的γ-羧基化蛋白质中的大多数在 凝血和骨稳态，GGCX在大多数组织（包括乳腺）中的存在表明 更广泛的生理作用。我们已经证明三阴性乳腺癌 （TNBC）细胞系表达GGCX并响应于维生素K1（叶绿醌）产生γ-羧化蛋白， 主要的饮食形式。在TNBC细胞中，K1处理富集干细胞标志物醛脱氢酶 1（ALDH 1），并促进乳腺球形成。这些数据表明，K1维持GGXC介导的γ- 羧基化驱动侵袭性乳腺癌表型。通过分析基因组癌症数据集，我们 发现约25%的乳腺肿瘤表达GGCX和维生素K氧化还原酶（VKOR）基因， 活动患有这种肿瘤的患者比那些肿瘤不表达这些基因的患者的生存率更低， 高水平。患有这种肿瘤亚型的患者将是限制K1可用性和/或 抑制GGCX。令人惊讶的是，我们发现维生素K2（甲基萘醌-4），另一种天然存在的形式， 在饮食中，不刺激TNBC细胞中的γ-羧化或干细胞表型，而是强烈抑制 细胞生长、迁移和能量代谢。这些令人激动的数据表明，K1和K2发挥了不同的作用， 对乳腺癌细胞的作用，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异戊烯基转移酶结构域1（UBIAD 1） 在TNBC中检测不到，表明维生素K的细胞处理改变。在目标1中，我们将剖析 K1和K2在体外，评估UBIAD 1的作用，并进行喂养研究，以测量K1的积累 和K2在TNBC异种移植物和宿主乳腺中与肿瘤生长的关系。在目标2中，我们将确定 从TNBC细胞中缺失GGCX是否影响γ-羧化蛋白质合成和侵袭性 表型在体外和体内。目的3将鉴定相关的γ-羧基化GGCX底物蛋白， K1的影响。我们预期具有高GGCX活性和低UBIAD 1的肿瘤的生长将被刺激， 高K1饮食和抑制高K2饮食。这些发现将确定GGCX为致癌基因， 维生素K通路作为晚期乳腺癌患者亚组的治疗靶点。

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.