In the present study, we performed drug screening to identify effective drugs against CSCs using miPS-CSCs, the miPS-derived models of CSCs. miPS-CSCs could serve as an advanced model for the development of anti-CSC drugs. Thus, we concluded that the generated miPS-CSCs established their niche in vitro by autonomously sustaining self-renewal and differentiation, consistent with the endothelial/perivascular niche of CSCs. Additionally, we reported that culturing miPS-LLCcm cells without the differentiated population influenced the endothelial differentiation capacity of CSCs, thereby suggesting that the signal(s) from the endothelial cells contribute to endothelial differentiation of CSCs. Notch signaling in self-renewing CSCs of miPS-LLCcm is likely to be activated by factor(s) secreted from the endothelial-like cells that were differentiated from CSCs of miPS-LLCcm. The miPS-LLCcm cell line (miPSC-CSC differentiated with Lewis lung carcinoma conditioned medium) has been demonstrated to exhibit self-renewal ability by treatment with factors secreted not only autocrinally from the CSCs, but also paracrinally from the differentiated progeny of miPS-LLCcm cells. These miPSCs-derived CSCs (miPS-CSCs) could be maintained in vitro under conditions that allow spontaneous differentiation. Recently, we have established mouse induced pluripotent stem cells (miPSCs) that possess self-renewal and differentiation capacities, as well as malignant tumorigenicity, which is in strong agreement with the definition of CSC.

However, the maintenance and amplification of CSCs and the reconstruction of their niche in vitro are challenging when conducting large-scale drug screening. Given that CSC properties are regulated by the CSC niche, drug screening should be carried out in the presence of CSC niches. Thus, further understanding not only the nature of CSC itself but also the relationship between CSCs and their microenvironment is required for the development of treatment strategies that can effectively eliminate CSCs from tumors. Recent studies have revealed that the tumor microenvironment also plays important roles in the development of resistance to therapy. The mechanisms underlying CSC-mediated resistance have been explained from various points of view, such as the expression of multi drug antiporters and slower cell cycle progression of CSC (quiescent/dormant states) in tumors. Multiple studies have consistently reported that the higher resistance capacity of CSCs against chemo- and/or radio-therapies compared to those of non-stem cancer cells significantly contributes to CSC survival after treatment. The current findings provided the basis for further studies on CSC-targeted drugs for the development of cancer treatment strategies.Д¬ancer stem cells (CSCs) are considered to be responsible for various pathological phenomena in cancer, such as tumor initiation, growth, tumor vascularization, recurrence, and metastasis. Moreover, no obvious ICAD reduction/degradation was detected.Д¬onclusion: Daunorubicin effectively eliminated CSCs, which are dependent on the p53/caspase signaling cascade.

This was also suppressed by treatment with a Ca 2+-specific chelator, which suggested that CAD endonuclease does not contribute. Treatment with the caspase inhibitor abolished daunorubicin-induced DNA fragmentation and was therefore considered to act downstream of caspase activation. Daunorubicin-induced apoptosis was found to be associated with p53 accumulation, activation of the caspase cascade, and oligonucleosomal DNA fragmentation. Results: Drug screening studies showed that daunorubicin, a topoisomerase II inhibitor, is specifically cytotoxic to miPS-CSCs. Apoptosis was analyzed by flow cytometry and western blotting. Drug screening was performed on these cells or after transplantation into mice. Methods: CSCs were obtained from mouse induced pluripotent stem cells (miPSCs) using cancer cell-conditioned media. Aim: To identify a drug that can effectively eliminate these cancer stem cells (CSCs) and determine its mode of action.

Icad antibody