Over the recent decade, the calcium-based assays have gained much popularity in order to discover new drugs. Since breast cancer is the second cause of death in the female population, rapid and effective methods are needed to screen drug compounds with fewer side effects. Human epidermal growth factor receptor 2 (HER2) increases intracellular free Ca²⁺ on its signaling pathways. In the present study, BT474 cell line, which overexpresses HER2 receptor, was selected and using fura-2-AM, intracellular Ca²⁺ release was investigated. The changes in the concentration of intracellular Ca²⁺ were evaluated by variation in the amount of fluorescence intensity. In the presence of epidermal growth factor (EGF), an increase in fluorescence intensity was observed so that after 20 min it raised to the maximum level. After treatment of BT474 cells by lapatinib, as a tyrosine kinase inhibitor (TKI), the signaling pathway of EGFR/HER2 heterodimer was significantly inhibited, which resulted in a decrease in Ca²⁺ entry into the cytoplasm and fluorescence emission decreased. The IC₅₀ value for the effect of lapatinib on BT474 cells was 113.2 nmol/L. Our results suggest this method is a simple, efficient and specific approach and can potentially be useful for screening new drug candidates against EGFR/HER2 heterodimer signaling pathways.

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在最近的十年中，基于钙的测定法已经广受欢迎，以发现新药。由于乳腺癌是女性人群中第二大死亡原因，因此需要快速有效的方法来筛选副作用较小的药物化合物。人表皮生长因子受体2（HER2）增加其信号通路上的细胞内游离Ca ²⁺。在本研究中，选择了过表达HER2受体的BT474细胞系，并使用fura-2-AM研究了细胞内Ca ^2+的释放。细胞内Ca ²⁺浓度的变化通过改变荧光强度的量来评价。在存在表皮生长因子（EGF）的情况下，观察到荧光强度增加，因此20分钟后荧光强度增加到最大水平。用拉帕替尼作为​​酪氨酸激酶抑制剂（TKI）处理BT474细胞后，EGFR / HER2异二聚体的信号通路被显着抑制，导致Ca ²⁺进入细胞质的减少，荧光发射减少。拉帕替尼对BT474细胞的作用的IC ₅₀值为113.2 nmol / L。我们的结果表明，该方法是一种简单，有效且特定的方法，可能潜在地用于筛选针对EGFR / HER2异二聚体信号通路的候选新药物。

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