Bayer AG, Drug Discovery, 13353, Berlin, Germany.
Institute for Biotechnology, Bioanalytics, Technical University Berlin, 13355, Berlin, Germany.
Cell Death Dis. 2018 Feb 7;9(2):192. doi: 10.1038/s41419-017-0202-5.
Cancer stem cells (CSCs) are involved in metastasis and resistance development, thus affecting anticancer therapy efficacy. The underlying pathways required for CSC maintenance and survival are not fully understood and only a limited number of treatment strategies to specifically target CSCs have been identified. To identify novel CSC targeting compounds, we here set-up an aldehyde dehydrogenase (ALDH)-based phenotypic screening system that allows for an automated and standardized identification of CSCs. By staining cancer cells for ALDH activity and applying high-content-based single-cell population analysis, the proportion of a potential CSC subpopulation with significantly higher ALDH activity (ALDH) can be quantified in a heterogeneous cell population. We confirmed high ALDH activity as surrogate marker for the CSC subpopulation in vitro and validated Wnt signaling as an essential factor for the maintenance of CSCs in SUM149 breast cancer cells. In a small molecule screen, we identified phosphodiesterase type 5 (PDE5) inhibition as potential strategy to target CSC maintenance and survival in multiple cancer cell lines. CSC elimination by PDE5 inhibition was not dependent on PKG signaling, and we suggest a novel mechanism in which PDE5 inhibition leads to elevated cGMP levels that stimulate cAMP/PKA signaling to eliminate CSCs.
癌症干细胞 (CSCs) 参与转移和耐药性的发展，从而影响抗癌治疗的疗效。CSC 维持和存活所需的潜在途径尚未完全了解，并且仅确定了有限数量的专门针对 CSC 的治疗策略。为了鉴定新型 CSC 靶向化合物，我们在此建立了基于醛脱氢酶 (ALDH) 的表型筛选系统，该系统允许自动且标准化地鉴定 CSCs。通过对癌细胞进行 ALDH 活性染色，并应用基于高内涵的单细胞群体分析，可以在异质细胞群体中定量鉴定具有显著更高 ALDH 活性 (ALDH) 的潜在 CSC 亚群的比例。我们在体外证实了高 ALDH 活性作为 CSC 亚群的替代标志物，并验证了 Wnt 信号作为 SUM149 乳腺癌细胞中 CSC 维持的必需因素。在小分子筛选中，我们确定磷酸二酯酶 5 (PDE5) 抑制是靶向多种癌细胞系中 CSC 维持和存活的潜在策略。PDE5 抑制对 CSC 的消除不依赖于 PKG 信号，我们提出了一种新的机制，其中 PDE5 抑制导致 cGMP 水平升高，从而刺激 cAMP/PKA 信号消除 CSCs。
