Kim Su-Hyeong, Kaschula Catherine H, Priedigkeit Nolan, Lee Adrian V, Singh Shivendra V
From the Department of Pharmacology and Chemical Biology and University of Pittsburgh Cancer Institute, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213 and.
the Department of Chemistry, University of Cape Town, Rondebosch, Cape Town 7701, South Africa.
J Biol Chem. 2016 Jun 24;291(26):13495-508. doi: 10.1074/jbc.M116.715219. Epub 2016 Apr 29.
Diallyl trisulfide (DATS), a metabolic byproduct of garlic, is known to inhibit the growth of breast cancer cells in vitro and in vivo This study demonstrates that DATS targets breast cancer stem cells (bCSC). Exposure of MCF-7 and SUM159 human breast cancer cells to pharmacological concentrations of DATS (2.5 and 5 μm) resulted in dose-dependent inhibition of bCSC, as evidenced by a mammosphere assay and flow cytometric analysis of aldehyde dehydrogenase 1 (ALDH1) activity and the CD44(high)/CD24(low)/epithelial specific antigen-positive fraction. DATS-mediated inhibition of bCSC was associated with a decrease in the protein level of FoxQ1. Overexpression of FoxQ1 in MCF-7 and SUM159 cells increased ALDH1 activity and the CD49f(+)/CD24(-) fraction. Inhibition of ALDH1 activity and/or mammosphere formation upon DATS treatment was significantly attenuated by overexpression of FoxQ1. In agreement with these results, stable knockdown of FoxQ1 using small hairpin RNA augmented bCSC inhibition by DATS. Expression profiling for cancer stem cell-related genes suggested that FoxQ1 may negatively regulate the expression of Dachshund homolog 1 (DACH1), whose expression is lost in invasive breast cancer. Chromatin immunoprecipitation confirmed recruitment of FoxQ1 at the DACH1 promoter. Moreover, inducible expression of DACH1 augmented DATS-mediated inhibition of bCSC. Expression of FoxQ1 protein was significantly higher in triple-negative breast cancer cases compared with normal mammary tissues. Moreover, an inverse association was observed between FoxQ1 and DACH1 gene expression in breast cancer cell lines and tumors. DATS administration inhibited ALDH1 activity in vivo in SUM159 xenografts. These results indicate that FoxQ1 is a novel target of bCSC inhibition by DATS.
二烯丙基三硫化物（DATS）是大蒜的一种代谢副产物，已知其在体外和体内均可抑制乳腺癌细胞的生长。本研究表明，DATS靶向乳腺癌干细胞（bCSC）。将MCF-7和SUM159人乳腺癌细胞暴露于药理学浓度的DATS（2.5和5μm）导致bCSC受到剂量依赖性抑制，这通过乳腺球形成试验以及醛脱氢酶1（ALDH1）活性和CD44（高）/CD24（低）/上皮特异性抗原阳性部分的流式细胞术分析得以证实。DATS介导的bCSC抑制与FoxQ1蛋白水平的降低有关。在MCF-7和SUM159细胞中过表达FoxQ1可增加ALDH1活性和CD49f（+）/CD24（-）部分。FoxQl过表达可显著减弱DATS处理后对ALDH1活性和/或乳腺球形成的抑制作用。与这些结果一致，使用小发夹RNA稳定敲低FoxQ1可增强DATS对bCSC的抑制作用。癌症干细胞相关基因的表达谱分析表明，FoxQ1可能负向调节腊肠犬同源物1（DACH1）的表达，而DACH1在浸润性乳腺癌中表达缺失。染色质免疫沉淀证实FoxQ1在DACH1启动子处的募集。此外，DACH1的诱导表达增强了DATS介导的对bCSC的抑制作用。与正常乳腺组织相比，三阴性乳腺癌病例中FoxQ1蛋白的表达明显更高。此外，在乳腺癌细胞系和肿瘤中观察到FoxQ1与DACH1基因表达呈负相关。给予DATS可在体内抑制SUM159异种移植瘤中的ALDH1活性。这些结果表明，FoxQ1是DATS抑制bCSC的一个新靶点。
