Subtype-specific accumulation of intracellular zinc pools is associated with the malignant phenotype in breast cancer.
Subtype-specific accumulation of intracellular zinc pools is associated with the malignant phenotype in breast cancer.
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DOI：
10.1186/s12943-015-0486-y
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发表时间：
2016-01-05
期刊：
影响因子：
37.3
通讯作者：
Kelleher SL
中科院分区：
文献类型：
--
作者：
Chandler P;Kochupurakkal BS;Alam S;Richardson AL;Soybel DI;Kelleher SL
与正常乳腺上皮相比，锌（Zn）在乳腺肿瘤和恶性细胞系中过度积累。锌积累的机制和锌失调的后果知之甚少。采用基因芯片技术研究了人类乳腺肿瘤和乳腺癌细胞系中锌转运蛋白和金属硫蛋白（MT）的表达差异。采用实时PCR和免疫印迹法分析代表性管腔（T47 D）、基底（MDA-MB-231）和非恶性（MCF 10A）细胞系中锌转运蛋白的表达。锌在人类肿瘤中的分布进行了评估，通过X射线荧光成像。使用FluoZin-3成像、定量和原子吸收光谱法测量细胞系中的Zn分布和含量。ZnT 2在MDA-MB-231细胞中过表达的功能后果包括侵袭、增殖和细胞周期分别使用Boyden小室、MTT测定和流式细胞术测量。人类乳腺肿瘤和乳腺癌细胞系的基因表达谱鉴定了锌转运网络中的亚型特异性失调。乳腺肿瘤组织的X射线荧光成像显示，在管腔型乳腺肿瘤的边缘处锌过度积聚，而在基底部肿瘤内锌分布更均匀。虽然T47 D和MDA-MB-231细胞相对于MCF 10A细胞过度积累Zn，但T47 D细胞积累的Zn是MDA-MB-231细胞的2.5倍。FluoZin-3成像表明，Zn被隔离到T47 D细胞中的许多大囊泡中，但保留在细胞质中，并在MDA-MB-231细胞中发现更少和更大的无定形亚细胞区室中。锌定位的差异反映了锌转运蛋白ZnT 2的相对丰度; T47 D细胞过度表达ZnT 2，而MDA-MB-231细胞由于蛋白酶体降解而不表达ZnT 2蛋白。为了确定MDA-MB-231细胞中缺乏ZnT 2的功能相关性，转染细胞以表达ZnT 2。ZnT 2过表达导致锌囊泡化，细胞周期的转变，增强凋亡，并减少增殖和侵袭。这种对恶性乳腺肿瘤和细胞系中锌转运网络的全面分析表明，锌管理的不同亚型特异性失调可能是乳腺癌表型特征的基础，如等级、侵袭性、转移潜力和对治疗的反应。本文的在线版本（doi：10.1186/s12943-015-0486-y）包含补充材料，可供授权用户使用。
Zinc (Zn) hyper-accumulates in breast tumors and malignant cell lines compared to normal mammary epithelium. The mechanisms responsible for Zn accumulation and the consequence of Zn dysregulation are poorly understood. Microarrays were performed to assess differences in the expression of Zn transporters and metallothioneins (MTs) in human breast tumors and breast cancer cell lines. Real-time PCR and immunoblotting were employed to profile Zn transporter expression in representative luminal (T47D), basal (MDA-MB-231), and non-malignant (MCF10A) cell lines. Zn distribution in human tumors was assessed by X-ray fluorescence imaging. Zn distribution and content in cell lines was measured using FluoZin-3 imaging, and quantification and atomic absorption spectroscopy. Functional consequences of ZnT2 over-expression in MDA-MB-231 cells including invasion, proliferation, and cell cycle were measured using Boyden chambers, MTT assays, and flow cytometry, respectively. Gene expression profiling of human breast tumors and breast cancer cell lines identified subtype-specific dysregulation in the Zn transporting network. X-ray fluorescence imaging of breast tumor tissues revealed Zn hyper-accumulation at the margins of Luminal breast tumors while Zn was more evenly distributed within Basal tumors. While both T47D and MDA-MB-231 cells hyper-accumulated Zn relative to MCF10A cells, T47D cells accumulated 2.5-fold more Zn compared to MDA-MB-231 cells. FluoZin-3 imaging indicated that Zn was sequestered into numerous large vesicles in T47D cells, but was retained in the cytoplasm and found in fewer and larger, amorphous sub-cellular compartments in MDA-MB-231 cells. The differences in Zn localization mirrored the relative abundance of the Zn transporter ZnT2; T47D cells over-expressed ZnT2, whereas MDA-MB-231 cells did not express ZnT2 protein due to proteasomal degradation. To determine the functional relevance of the lack of ZnT2 in MDA-MB-231cells, cells were transfected to express ZnT2. ZnT2 over-expression led to Zn vesicularization, shifts in cell cycle, enhanced apoptosis, and reduced proliferation and invasion. This comprehensive analysis of the Zn transporting network in malignant breast tumors and cell lines illustrates that distinct subtype-specific dysregulation of Zn management may underlie phenotypic characteristics of breast cancers such as grade, invasiveness, metastatic potential, and response to therapy. The online version of this article (doi:10.1186/s12943-015-0486-y) contains supplementary material, which is available to authorized users.