Department of Obstetrics and Gynecology, Alpert Medical School, Brown University, Providence, RI 02905, USA.
Gynecol Oncol. 2011 Nov;123(2):370-8. doi: 10.1016/j.ygyno.2011.07.002. Epub 2011 Jul 30.
In human trials calcitriol and its analogs displayed unacceptable systemic toxicities including hypercalcemia. This study was designed to evaluate a novel non-hypercalcemic vitamin-D derivative (MT19c) and its anticancer effects in cultured ovarian cancer cell model.
We modified the Ergocalciferol structure to generate MT19c, a heterocyclic vitamin-D derivative. Hypercalcemic liabilities of MT19c were assessed by estimating the blood calcium levels in drug treated animals. VDR agonistic or antagonistic properties of MT19c were determined via a VDR-coactivator binding assay. The anticancer effects of MT19c were evaluated by (i) cytotoxicity studies in cancer cell lines and the National Cancer Institute (NCI(60)) cell lines, (ii) identification of apoptosis markers by microscopy and western blots, (iii) cell cycle analysis, and (iv) by studying the insulin receptor substrate-1/2 (IRS1/2) signaling in ovarian cancer cells (SKOV-3) by western blotting.
MT19c treatment did not cause hypercalcemia in mice and showed minor VDR antagonistic activity. In a NCI(60) screen MT19c revealed cell-type specific growth inhibition. MT19c displayed superior cytotoxicity to cisplatin, calcitriol, EB1089 and Iressa in SKOV-3 cell-lines and was comparable to Taxol in our in vitro assays. In SKOV-3 cells MT19c showed caspase dependent apoptosis, DNA fragmentation and cell cycle arrest. MT19c did not alter VDR but downregulated the IGFR/IRS-1/2-MEK-ras-ERK1/2-pathway via activated TNFα-receptor/SAPK/JNK component.
Our results demonstrate how structural optimization of the vitamin-D scaffold leads to identification of a non-hypercalcemic compound MT19c which exerts cytotoxicity in vitro based on a VDR-independent signaling pathway and displays potent anti-cancer activity in ovarian cancer cell models.
在人体试验中，钙三醇及其类似物表现出不可接受的全身毒性，包括高钙血症。本研究旨在评估一种新型非高钙血症维生素 D 衍生物（MT19c）及其在培养的卵巢癌细胞模型中的抗癌作用。
我们修改了麦角钙化醇的结构，生成了 MT19c，一种杂环维生素 D 衍生物。通过估计药物处理动物的血钙水平来评估 MT19c 的高钙血症风险。通过 VDR-共激活剂结合测定来确定 MT19c 的 VDR 激动或拮抗性质。通过（i）在癌细胞系和国家癌症研究所（NCI（60））细胞系中的细胞毒性研究，（ii）通过显微镜和蛋白质印迹鉴定凋亡标志物，（iii）细胞周期分析，以及（iv）通过蛋白质印迹研究卵巢癌细胞（SKOV-3）中的胰岛素受体底物-1/2（IRS1/2）信号转导来评估 MT19c 的抗癌作用。
MT19c 治疗不会引起小鼠高钙血症，并且显示出轻微的 VDR 拮抗活性。在 NCI（60）筛选中，MT19c 显示出细胞类型特异性的生长抑制。MT19c 在 SKOV-3 细胞系中的细胞毒性优于顺铂、钙三醇、EB1089 和 Iressa，并且在我们的体外测定中与紫杉醇相当。在 SKOV-3 细胞中，MT19c 显示出 caspase 依赖性凋亡、DNA 片段化和细胞周期停滞。MT19c 不会改变 VDR，但通过激活 TNFα 受体/SAPK/JNK 成分下调 IGF1R/IRS-1/2-MEK-ras-ERK1/2 通路。
我们的结果表明，维生素 D 支架的结构优化如何导致识别出一种非高钙血症化合物 MT19c，该化合物通过一种非 VDR 依赖的信号通路在体外发挥细胞毒性，并在卵巢癌细胞模型中显示出强大的抗癌活性。
