Abstract
The molecular link between stress and carcinogenesis and the positive outcomes of stress intervention in cancer therapy have recently been well documented. Cancer stem cells (CSCs) facilitate cancer malignancy, drug resistance, and relapse and, hence, have emerged as a new therapeutic target. Here, we aimed to investigate the effect of three previously described antistress compounds (triethylene glycol, TEG; Withanone, Wi-N, and Withaferin A, Wi-A) on the stemness and differentiation characteristics of cancer cells. Breast carcinoma, glioblastoma, and neuroblastoma cells were treated with a non-toxic concentration of TEG (0.1%), Wi-N (5 µM), and Wi-A (0.1 µM) in 2D and 3D cultures. The results demonstrated that TEG, Wi-N, and Wi-A suppressed the stemness properties, which was linked with their inhibition of epithelial-mesenchymal transition (EMT) signaling. In particular, Wi-N and TEG caused a stronger reduction in the self-renewal capability of CSCs than Wi-A, as evidenced by a tumor spheroid formation assay and analyses of stemness-related genes (ALDH1, CD44, NANOG, CD133, SOX2). Furthermore, TEG and Wi-N caused the differentiation of cancer cells. Each of these was supported by (i) the upregulation of KRT18, KRT19, E-cadherin, and downregulation of vimentin in breast carcinoma; (ii) increased levels of GFAP, MAP2, and PSD-95 in astrocytoma; and (iii) increased NeuN, GAP-43, and NF200 levels in neuroblastoma. Furthermore, a reduction in cancer progression-related proteins (PI3K, N-myc) was recorded in treated cells. Our results suggest that TEG and Wi-N may be recruited to target cancer cell stemness and differentiation therapy.