Upregulated CCL20 and CCR6 in Cancer Stem Cells Converted from Mouse iPS Cells

Background: Cancer stem cells (CSCs) as a class of malignant cancer cells play an important role in tumor progression. Previous studies by our group have demonstrated the establishment of the model of CSCs converting mouse iPS cells (miPSCs) into CSCs by treating the miPSCs with a conditioned medium (CM) of Lewis Lung Carcinoma (LLC) cells with or without the nonmutagenic chemical compounds. CSCs converted from miPSCs developed highly malignant adenocarcinoma when subcutaneously transplanted into the nude mice. Methods: The miPSCs were treated with each compound for 1 week in the presence of a CM of LLC cells. We evaluated the gene expression in the resultant CSCs comparing that in miPSCs by microarray analysis. And the expression of chemokine (C-C motif) ligand 20 (CCL20) and C-C chemokine receptor type 6 (CCR6) in converted cells were evaluated by rt-qPCR. The CCR6 expression in converted cells and primary cells were determined by flow cytometry. Results: As the result, the expression of CCL20 was found upregulated in the presence of CM supplemented with PD0325901. Then we assessed the expression of CCR6, which was considered to be stimulated by CCL20. Then the expression of CCR6 was also found up-regulated. Interestingly, IL17A expression was also observed only in the CSCs from the primary tumor implying the effect of tumor microenvironment. Moreover, significantly high level of CCR6 was showed in flow cytometric analysis. Conclusion: These results suggest that a model of CSCs with CCL20-CCR6 autocrine loop was obtained as the result of the conversion of iPSCs. This CSC should be a good model to study targeting CCR6 as a G protein-coupled receptor (GPCR)

Signaling Inhibitors Accelerate the Conversion of mouse iPS Cells into Cancer Stem Cells in the Tumor Microenvironment

Cancer stem cells (CSCs) are a class of cancer cells characterized by self-renewal, differentiation and tumorigenic potential. We previously established a model of CSCs by culturing mouse induced pluripotent stem cells (miPSCs) for four weeks in the presence of a conditioned medium (CM) of cancer cell lines, which functioned as the tumor microenvironment. Based on this methodology of developing CSCs from miPSCs, we assessed the risk of 110 non-mutagenic chemical compounds, most of which are known as inhibitors of cytoplasmic signaling pathways, as potential carcinogens. We treated miPSCs with each compound for one week in the presence of a CM of Lewis lung carcinoma (LLC) cells. However, one-week period was too short for the CM to convert miPSCs into CSCs. Consequently, PDO325901 (MEK inhibitor), CHIR99021 (GSK-3 beta inhibitor) and Dasatinib (Abl, Src and c-Kit inhibitor) were found to confer miPSCs with the CSC phenotype in one week. The tumor cells that survived exhibited stemness markers, spheroid formation and tumorigenesis in Balb/c nude mice. Hence, we concluded that the three signal inhibitors accelerated the conversion of miPSCs into CSCs. Similarly to our previous study, we found that the PI3K-Akt signaling pathway was upregulated in the CSCs. Herein, we focused on the expression of relative genes after the treatment with these three inhibitors. Our results demonstrated an increased expression of pik3ca, pik3cb, pik3r5 and pik3r1 genes indicating class IA PI3K as the responsible signaling pathway. Hence, AKT phosphorylation was found to be up-regulated in the obtained CSCs. Inhibition of Erk1/2, tyrosine kinase, and/or GSK-3 beta was implied to be involved in the enhancement of the PI3K-AKT signaling pathway in the undifferentiated cells, resulting in the sustained stemness, and subsequent conversion of miPSCs into CSCs in the tumor microenvironment

Daunorubicin can eliminate iPS-derived cancer stem cells via ICAD/CAD-independent DNA fragmentation

Aim: To identify a drug that can effectively eliminate these cancer stem cells (CSCs) and determine its mode of action.Methods: CSCs were obtained from mouse induced pluripotent stem cells (miPSCs) using cancer cell-conditioned media. Drug screening was performed on these cells or after transplantation into mice. Apoptosis was analyzed by flow cytometry and western blotting.Results: Drug screening studies showed that daunorubicin, a topoisomerase II inhibitor, is specifically cytotoxic to miPS-CSCs. Daunorubicin-induced apoptosis was found to be associated with p53 accumulation, activation of the caspase cascade, and oligonucleosomal DNA fragmentation. Treatment with the caspase inhibitor abolished daunorubicin-induced DNA fragmentation and was therefore considered to act downstream of caspase activation. This was also suppressed by treatment with a Ca2+-specific chelator, which suggested that CAD endonuclease does not contribute. Moreover, no obvious ICAD reduction/degradation was detected.Conclusion: Daunorubicin effectively eliminated CSCs, which are dependent on the p53/caspase signaling cascade. The current findings provided the basis for further studies on CSC-targeted drugs for the development of cancer treatment strategies

Upregulated CCL20 and CCR6 in Cancer Stem Cells Converted from Mouse iPS Cells

Background: Cancer stem cells (CSCs) as a class of malignant cancer cells play an important role in tumor progression. Previous studies by our group have demonstrated the establishment of the model of CSCs converting mouse iPS cells (miPSCs) into CSCs by treating the miPSCs with a conditioned medium (CM) of Lewis Lung Carcinoma (LLC) cells with or without the nonmutagenic chemical compounds. CSCs converted from miPSCs developed highly malignant adenocarcinoma when subcutaneously transplanted into the nude mice. Methods: The miPSCs were treated with each compound for 1 week in the presence of a CM of LLC cells. We evaluated the gene expression in the resultant CSCs comparing that in miPSCs by microarray analysis. And the expression of chemokine (C-C motif) ligand 20 (CCL20) and C-C chemokine receptor type 6 (CCR6) in converted cells were evaluated by rt-qPCR. The CCR6 expression in converted cells and primary cells were determined by flow cytometry. Results: As the result, the expression of CCL20 was found upregulated in the presence of CM supplemented with PD0325901. Then we assessed the expression of CCR6, which was considered to be stimulated by CCL20. Then the expression of CCR6 was also found up-regulated. Interestingly, IL17A expression was also observed only in the CSCs from the primary tumor implying the effect of tumor microenvironment. Moreover, significantly high level of CCR6 was showed in flow cytometric analysis. Conclusion: These results suggest that a model of CSCs with CCL20-CCR6 autocrine loop was obtained as the result of the conversion of iPSCs. This CSC should be a good model to study targeting CCR6 as a G protein-coupled receptor (GPCR)

β-Thujaplicin Enhances TRAIL-Induced Apoptosis via the Dual Effects of XIAP Inhibition and Degradation in NCI-H460 Human Lung Cancer Cells

Background: β-thujaplicin, a natural tropolone derivative, has anticancer effects on various cancer cells via apoptosis. However, the apoptosis regulatory proteins involved in this process have yet to be revealed. Methods: Trypan blue staining, a WST-8 assay, and a caspase-3/7 activity assay were used to investigate whether β-thujaplicin sensitizes cancer cells to TNF-related apoptosis-inducing ligand (TRAIL)-mediated apoptosis. Additionally, western blotting was performed to clarify the effects of β-thujaplicin on X-linked inhibitor of apoptosis protein (XIAP) in NCI-H460 cells and a fluorescence polarization binding assay was used to evaluate the binding-inhibitory activity of β-thujaplicin against XIAP-BIR3. Results: β- and γ-thujaplicins decreased the viability of NCI-H460 cells in a dose-dependent manner; they also sensitized the cells to TRAIL-induced cell growth inhibition and apoptosis. β-thujaplicin significantly potentiated the apoptosis induction effect of TRAIL on NCI-H460 cells, which was accompanied by enhanced caspase-3/7 activity. Interestingly, β-thujaplicin treatment in NCI-H460 cells decreased XIAP levels. Furthermore, β-thujaplicin was able to bind XIAP-BIR3 at the Smac binding site. Conclusions: These findings indicate that β-thujaplicin could enhance TRAIL-induced apoptosis in NCI-H460 cells via XIAP inhibition and degradation. Thus, the tropolone scaffold may be useful for designing novel nonpeptidic small-molecule inhibitors of XIAP and developing new types of anticancer drugs