Departamento de Biología, Bioquímica & Farmacia, Universidad Nacional del Sur-CONICET, 8000 Bahía Blanca, Argentina.
Departamento de Biología, Bioquímica & Farmacia, Universidad Nacional del Sur-CONICET, 8000 Bahía Blanca, Argentina.
J Steroid Biochem Mol Biol. 2014 Oct;144 Pt A:197-200. doi: 10.1016/j.jsbmb.2013.11.014. Epub 2013 Dec 5.
We have previously shown that 1α,25(OH)2-Vitamin D3 [1α,25(OH)2D3] and its less calcemic analog TX 527 inhibit the proliferation of endothelial cells transformed by the viral G protein-coupled receptor associated to Kaposi sarcoma (vGPCR) and this could be partially explained by the inhibition of the NF-κB pathway. In this work, we further explored the mechanism of action of both vitamin D compounds in Kaposi sarcoma. We investigated whether the cell cycle arrest and subsequent apoptosis of endothelial cells (SVEC) and SVEC transformed by vGPCR (SVEC-vGPCR) elicited by 1α,25(OH)2D3 and TX 527 were mediated by the vitamin D receptor (VDR). Cell cycle analysis of SVEC and SVEC-vGPCR treated with 1α,25(OH)2D3 (10nM, 48h) revealed that 1α,25(OH)2D3 increased the percentage of cells in the G0/G1 phase and diminished the percentage of cells in the S phase of the cell cycle. Moreover, the number of cells in the S phase was higher in SVEC-vGPCR than in SVEC due to vGPCR expression. TX 527 exerted similar effects on growth arrest in SVEC-vGPCR cells. The cell cycle changes were suppressed when the expression of the VDR was blocked by a stable transfection of shRNA against VDR. Annexin V-PI staining demonstrated apoptosis in both SVEC and SVEC-vGPCR after 1α,25(OH)2D3 and TX 527 treatment (10nM, 24h). Cleavage of caspase-3 detected by Western blot analysis was increased to a greater extent in SVEC than in SVEC-vGPCR cells, and this effect was also blocked in VDR knockdown cells. Altogether, these results suggest that 1α,25(OH)2D3 and TX 527 inhibit the proliferation of SVEC and SVEC-vGPCR and induce apoptosis by a mechanism that involves the VDR.
我们之前已经表明，1α，25（OH）2-维生素 D3[1α，25（OH）2D3]及其较少钙调素的类似物 TX 527 可抑制由病毒 G 蛋白偶联受体相关的卡波西肉瘤（vGPCR）转化的内皮细胞的增殖，这部分可以通过抑制 NF-κB 途径来解释。在这项工作中，我们进一步探讨了这两种维生素 D 化合物在卡波西肉瘤中的作用机制。我们研究了 1α，25（OH）2D3 和 TX 527 是否通过维生素 D 受体（VDR）介导内皮细胞（SVEC）和由 vGPCR 转化的 SVEC（SVEC-vGPCR）的细胞周期停滞和随后的细胞凋亡。用 1α，25（OH）2D3（10nM，48h）处理的 SVEC 和 SVEC-vGPCR 的细胞周期分析表明，1α，25（OH）2D3 增加了 G0/G1 期细胞的百分比，并减少了 S 期细胞的百分比细胞周期。此外，由于 vGPCR 的表达，SVEC-vGPCR 中的 S 期细胞数量高于 SVEC。TX 527 对 SVEC-vGPCR 细胞的生长抑制也产生了类似的作用。当 VDR 的表达被针对 VDR 的稳定转染 shRNA 阻断时，细胞周期变化受到抑制。用 1α，25（OH）2D3 和 TX 527（10nM，24h）处理后，SVEC 和 SVEC-vGPCR 均通过 Annexin V-PI 染色证实发生了细胞凋亡。通过 Western blot 分析检测到的 caspase-3 切割在 SVEC 中的增加程度大于 SVEC-vGPCR 细胞，并且这种作用在 VDR 敲低细胞中也被阻断。总的来说，这些结果表明，1α，25（OH）2D3 和 TX 527 通过涉及 VDR 的机制抑制 SVEC 和 SVEC-vGPCR 的增殖并诱导细胞凋亡。
