Regulation of intracellular calcium in human breast cancer cells
Regulation of intracellular calcium in human breast cancer cells
复制标题
DOI：
10.1385/endo:9:3:321
复制
发表时间：
1998-12-01
期刊：
影响因子：
3.7
通讯作者：
Rhoten, WB
中科院分区：
文献类型：
--
作者：
Sergeev, IN;Rhoten, WB
乳腺癌细胞内 Ca2+ 的调节可能对于调节细胞增殖、分化、凋亡和细胞毒性以及抗癌药物的作用机制很重要。其中一种药物，类固醇激素 1,25-二羟基维生素 D-3 [1,25(OH)(2)D-3]，与维持细胞 Ca2+ 稳态密切相关。本研究的目的是研究乳腺癌细胞中的 Ca2+ 调节途径，并确定 1,25(OH)(2)D-3 在调节这些途径中的作用。我们检查了雌激素受体阴性人乳腺癌细胞系 BT-20 中 Ca2+ 从细胞外空间进入和 Ca2+ 从细胞内储存的动员途径，采用荧光数字视频成像和 Ca2+ 指示剂 fura-2 来测量细胞内游离 Ca2+ ([Ca2+](i)) 的浓度和单细胞水平的 Ca2+ 反应。我们发现 BT-20 乳腺癌细胞表达非选择性、电压不敏感的 Ca2+ 通道 (VICC)，如它们对 Mn2+ 的通透性、对细胞外 Ca2+ 升高的反应以及 [Ca2+](i) 的增加所表明的那样。 La3+ 和 Ni2+ 的阻断，以及对 K+ 去极化的反应，[Ca2+](i) 和 Ca2+ 流入略有减少。没有证据表明 BT-20 细胞中存在电压依赖性 Ca2+ 通道。内质网 Ca2+ 储存包含主要的细胞内 Ca2+ 池，这在将名义上不含 Ca2+ 的缓冲液中的 Ca2+ 离子载体离子霉素应用于具有耗尽毒胡萝卜素的 Ca2+ 储存的细胞后显而易见。毒胡萝卜素消耗 Ca2+ 储备并没有增加细胞外 Ca2+ 的流入，这意味着电容性 Ca2+ 进入没有显着激活。 1,25(OH)(2)D-3 不会引起 [Ca2+](i) 快速升高，但通过 VICC 的 Ca2+ 流入增加。用 1,25(OH)(2)D-3 处理 4-72 小时显着增加了基础 [Ca2+](i) 显着升高的细胞百分比。这些细胞对毒胡萝卜素的 Ca2+ 反应减弱。总之，我们的研究结果表明，VICC 和毒胡萝卜素敏感的内质网 Ca2+ 储存是本研究中使用的乳腺癌细胞系中 Ca2+ 进入和 Ca2+ 动员的主要途径。 1,25(OH)(2)D-3 迅速增加通过 VICC 的 Ca2+ 流入，并且在长期治疗后，耗尽内质网 Ca2+ 储存。靶向 VICC 和内质网 Ca2+ 储存介导的 Ca2+ 信号传导可能代表一种治疗和化学预防乳腺癌的新方法。
Regulation of intracellular Ca2+ in breast cancer may be important in modulating cell proliferation, differentiation, apoptosis, and cytotoxicity, as well as contributing to mechanisms of action of anticancer agents. One of these agents, the steroid hormone 1,25-dihydroxy-vitamin D-3 [1,25(OH)(2)D-3], is intimately involved in maintaining cellular Ca2+ homeostasis, The purpose of this study was to investigate Ca2+ regulatory pathways in breast cancer cells and to determine the role of 1,25(OH)(2)D-3 in modulating these pathways. We examined pathways for Ca2+ entry from the extracellular space and Ca2+ mobilization from intracellular stores in the estrogen-receptor negative human breast cancer cell line BT-20, Fluorescence digital video imaging and Ca2+ indicator fura-2 were employed to measure the concentration of intracellular free Ca2+ ([Ca2+](i)) and Ca2+ responses at the single-cell level. We found that BT-20 breast cancer cells expressed nonselective, voltage-insensitive Ca2+ channels (VICC), as indicated by their permeability to Mn2+, response to elevated extracellular Ca2+ with an increase in [Ca2+](i). blockage by La3+ and Ni2+, and response to K+ depolarization with a slight decrease in [Ca2+](i) and Ca2+ influx. There was no evidence for voltage-dependent Ca2+ channels in BT-20 cells. Endoplasmic reticulum Ca2+ stores comprised a major intracellular Ca2+ pool, as was evident after application of a Ca2+ ionophore ionomycin in nominally Ca2+-free buffer to the cells with thapsigargin-depleted Ca2+ stores. Thapsigargin depletion of Ca2+ stores did not increase influx of extracellular Ca2+, implying no significant activation of the capacitative Ca2+ entry. 1,25(OH)(2)D-3 did not induce a rapid rise in [Ca2+](i), yet Ca2+ influx th rough VICC was increased. Treatment with 1,25(OH)(2)D-3 for 4-72 h significantly increased the percentage of cells with a markedly elevated basal [Ca2+](i). Ca2+ response of those cells to thapsigargin was attenuated, Taken together, our findings show that VICC and the thapsigargin-sensitive endoplasmic reticulum Ca2+ stores are the principal pathways For Ca2+ entry and Ca2+ mobilization in the breast cancer cell line used in this study. 1,25(OH)(2)D-3 rapidly increases Ca2+ influx through VICC and after a chronic treatment, depletes endoplasmic reticulum Ca2+ stores. Targeting of Ca2+ signaling mediated by VICC and endoplasmic reticulum Ca2+ stores may represent a novel approach to the treatment and chemoprevention of breast cancer.