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In healthy individuals, skin integrity is maintained by epidermal stem cells which self-renew and generate daughter cells that undergo terminal differentiation. Epidermal stem cells represent a promising source of stem cells, and their culture has great potential in scientific research and clinical application. However, no single method has been universally adopted for identifying and isolating epidermal stem cells. Here, we reported the isolation and characterization of putative epidermal stem cells from newborn mouse skin. The keratinocytes were separated enzymatically. Putative epidermal stem cells were selected by rapid adherence on a composite matrix made of type I collagen and fibronectin. Unattached cells were discarded after 10 min, and the attached cells were cultured in a defined culture medium. The isolated cells showed the typical epidermal stem cell morphology. Immunofluorescence indicated that the cells were strongly stained for β1 integrin family of extracellular matrix receptors. In conclusion, mouse putative epidermal stem cells were successfully isolated from newborn mouse epidermis on the basis of high rapid adhesion to extracellular matrix proteins and cultured in vitro.

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Oxidative stress refers to elevated levels of intracellular reactive oxygen species (ROS). ROS homeostasis functions as a signaling pathway for normal cell survival and appropriate cell signaling. Chronic inflammation induced by imbalanced levels of ROS contributes to many diseases and different types of cancer. ROS can alter the expression of oncogenes and tumor suppressor genes through epigenetic modifications, transcription factors, and non‐coding RNAs. MicroRNAs (miRNAs) are small non‐coding RNAs that play a key role in most biological pathways. Each miRNA regulates hundreds of target genes by inhibiting protein translation and/or promoting messenger RNA degradation. In normal conditions, miRNAs play a physiological role in cell proliferation, differentiation, and apoptosis. However, different factors that can dysregulate cell signaling and cellular homeostasis can also affect miRNA expression. The alteration of miRNA expression can work against disturbing factors or mediate their effects. Oxidative stress is one of these factors. Considering the complex interplay between ROS level and miRNA regulation and both of these with cancer development, we review the role of miRNAs in cancer, focusing on their function in oxidative stress.

Cytotoxic activities of acetylshikonin and acetoxyisovalerylshikonin alone and in combination with chemotherapeutic agents against parental and drug resistant cell lines were determined using the MTT assay. Effects of Shikonin derivatives on BCRP, MDR1 and MRP transcript and protein levels were relatively measured. Finally, accumulation and efflux kinetics were conducted. The results revealed cell- and concentration-dependency of the cell cytotoxicity. Acetylshikonin and acetoxyisovalerylshikonin transiently made the mRNA ocean turbulent, but FACS analyses using fluorescent-labeled antibodies showed no significant change in the MDR-protein levels. Functional kinetics revealed significant block of MDR1, BCRP and MRP transporter in the presence of shikonin derivatives. Maximum accumulation fold changes was quantified to be 4.4 and consequently, acetoxyisovalerylshikonin pretreated EPG85.257RDB cells was chemosensitized to daunorubicin tension 3.1-fold. Although, the MDR blockage was reported to follow time- and cell-dependent patterns, MDR1, BCRP and MRP2 responses to the shikonins are concentration-independent. These data suggest uncompetitive transporter blockage behavior of these agents. The results indicated that shikonin derivatives stimulate uptake and reduce efflux of chemotherapeutic agents in the malignant cancer cells, suggesting that chemotherapy in combination with shikonin compounds may be beneficial to cancer cells that overexpress multidrug resistance transporters.

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