ABSTRACT
Purpose: Stem cells can exhibit restorative effects with the commitment to functional cells.Cell-imprinted topographies provide adaptable templates and certain dimensions for thedifferentiation and bioactivity of stem cells. Cell sheet technology using the thermo-responsivepolymers detaches the "cell sheets" easier with less destructive effects on the extracellularmatrix (ECM). Here, we aim to dictate keratinocyte-like differentiation of mesenchymal stemcells (MSCs) by using combined cell imprinting and sheet technology. Methods: We developed the poly dimethyl siloxane (PDMS) substrate having keratinocytecell-imprinted topography grafted with the PNIPAAm polymer. Adipose tissue-derived MSCs(AT-MSCs) were cultured on PDMS substrate for 14 days and keratinocyte-like differentiationmonitored via the expression of involucrin, P63, and cytokeratin 14. Results: Data showed the efficiency of the current protocol in the fabrication of PDMSmolds. The culture of AT-MSCs induced typical keratinocyte morphology and up-regulatedthe expression of cytokeratin-14, Involucrin, and P63 compared to AT-MSCs cultured on theplastic surface (P < 0.05). Besides, KLC sheets were generated once slight changes occur in theenvironment temperature. Conclusion: These data showed the hypothesis that keratinocyte cell imprinted substrate canorient AT-MSCs toward KLCs by providing a specific niche and topography.
ABSTRACT
BACKGROUND: The Notch signaling pathway has a key role in angiogenesis and Delta - Like Ligand 4 (DLL4) is one of the main ligands of Notch involved in cell proliferation in sprouting vessels. OBJECTIVE: In this study, we aimed to evaluate the expression of DLL4 in primary breast tumors and to examine the effect of melatonin on DLL4 expression in vitro. METHODS: Eighty-five breast tumor and paired adjacent non-tumor tissue samples were collected. Apoptosis assay was performed on breast cancer cells to evaluate melatonin effects. Western blot and quantitative RT-PCR were used to measure DLL4 expression. Then, we investigated the effect of melatonin on the expression of DLL4 in four breast cancer cell lines at RNA and protein levels. We also performed a probabilistic neural network analysis to study genes closely associated with DLL4 expression. RESULTS: Our results showed a significantly higher expression of DLL4 in tumor tissues compared to non-tumor tissues (P = 0.027). Melatonin treatment substantially attenuated DLL4 expression in BT474 and MCF-7 cells, but not in SK-BR-3 and MDA-MB-231 cells. Also, melatonin induced apoptosis in all four cell lines. Network analysis revealed a set of 15 genes that had close association and interaction with DLL4. DLL4 was overexpressed in breast cancer tissues as compared to the non-tumor tissues. CONCLUSION: It can be concluded that melatonin treatment attenuated DLL4 expression only in estrogen- responsive breast cancer cells and is able to induce apoptosis in breast cancer cells.
