In‑Sook An

Identification of ultraviolet B radiation-induced microRNAs in normal human dermal papilla cells

Ultraviolet (UV) radiation impairs intracellular functions by directly damaging DNA and by indirectly generating reactive oxygen species (ROS), which induce cell cycle arrest and apoptosis. UV radiation can also alter gene expression profiles, including those of mRNA and microRNA (miRNA). The effects of UV radiation on cellular functions and gene expression have been widely documented in human skin cells such as keratinocytes, melanocytes and dermal fibroblasts, but the effect it has on other types of skin cell such as dermal papilla cells, which are crucial in the induction of hair follicle growth, remains unknown. In the current study, the effect of UV radiation on physiological changes and miRNA-based expression profiles in normal human dermal papilla cells (nHDPs) was investigated. UVB radiation of ≥50 mJ/cm2 displayed high cytotoxicity and apoptosis in a dose-dependent manner. In addition, ROS generation was exhibited in UVB-irradiated nHDPs. Furthermore, using miRNA microarray analysis, it was demonstrated that the expression profiles of 42 miRNAs in UVB-irradiated nHDPs were significantly altered compared with those in the controls (35 upregulated and 7 downregulated). The biological functions of the differentially expressed miRNAs were studied with gene ontology analysis to identify their putative target mRNAs, and were demonstrated to be involved in cell survival- and death-related functions. Overall, the results of the present study provide evidence that miRNA-based cellular mechanisms may be involved in the UVB-induced cellular response in nHDPs.

Asiaticoside, a component of Centella asiatica, inhibits melanogenesis in B16F10 mouse melanoma.

Melanogenesis is the process of generating pigmentation via melanin synthesis and delivery. Three key enzymes, tyrosinase, tyrosinase-related protein 1 (TRP1) and TRP2, metabolize melanin from L-tyrosine. Melanin synthesizing enzymes are regulated by microphthalmia-associated transcription factor (MITF). The titrated extract of Centella asiatica (TECA) contains the major components asiatic acid, asiaticoside and madecassic acid. The present study revealed that TECA reduces the melanin content in melanocytes. Moreover, the asiaticoside contained in TECA modulated melanogenesis by inhibiting tyrosinase mRNA expression. The decrease in tyrosinase mRNA levels was mediated through MITF. Uniquely, asiaticoside inhibited MITF by decreasing its DNA binding affinity. In conclusion, the results of the present study indicate that asiaticoside treatment may have beneficial effects in hyperpigmentation diseases or for skin whitening.

Benzo(a)pyrene represses melanogenesis in B16F10 mouse melanoma cells

Benzo(a)pyrene (BaP) is a chemically based polycyclic aromatic hydrocarbon (PAH) that is readily absorbed by the skin. BaP is metabolized to BaP-diol-epoxide by cytochromes P-450 1A1/2 (CYP1A1/2) and cytochromes P-450 1B1 (CYP1B1) in the cytosol. BaP and its metabolites induce genotoxicity and cancer. Although BaP easily accumulates in melanin-containing tissues as well as other tissue types, the effects of BaP on melanocytes are not fully understood. Here, we show that 40-100 µM BaP represses melanin synthesis in B16F10 cells. The decrease of melanin contents is induced by tyrosinase activity in BaP-exposed B16F10. However, this repression of melanin synthesis is not induced by direct inhibition of tyrosinase in in vitro assay. Therefore, we show whether BaP regulated melanin synthesis-related enzyme. BaP regulates melanin synthesis by Tyr and Tyrpl expression. In addition, these genes expression is down-regulated by Mitf repressed by BaP. Importantly, the repression was provoked in the absence and presence of α-melanocyte stimulating hormone (α-MSH). Therefore, we hypothesize BaP interrupts the UV protection mechanism by repressing melanin synthesis in the skin. Taken together our results have revealed new side effects that exposure of BaP abolished melanin synthesis in melanocytes.

Implication of microRNA regulation in para-phenylenediamine-induced cell death and senescence in normal human hair dermal papilla cells

Para-phenylenediamine (PPD) is a major component of hair coloring and black henna products. Although it has been largely demonstrated that PPD induces allergic reactions and increases the risk of tumors in the kidney, liver, thyroid gland and urinary bladder, the effect on dermal papilla cells remains to be elucidated. Therefore, the current study evaluated the effects of PPD on growth, cell death and senescence using cell-based assays and microRNA (miRNA) microarray in normal human hair dermal papilla cells (nHHDPCs). Cell viability and cell cycle analyses demonstrated that PPD exhibited a significant cytotoxic effect on nHHDPCs through inducing cell death and G2 phase cell cycle arrest in a dose-dependent manner. It was additionally observed that treatment of nHHDPCs with PPD induced cellular senescence by promoting cellular oxidative stress. In addition, the results of the current study indicated that these PPD-mediated effects were involved in the alteration of miRNA expression profiles. Treatment of nHHDPCs with PPD altered the expression levels of 74 miRNAs by ≥2-fold (16 upregulated and 58 downregulated miRNAs). Further bioinformatics analysis determined that these identified miRNA target genes were likely to be involved in cell growth, cell cycle arrest, cell death, senescence and the induction of oxidative stress. In conclusion, the observations of the current study suggested that PPD was able to induce several cytotoxic effects through alteration of miRNA expression levels in nHHDPCs.

Lenalidomide induces apoptosis and alters gene expression in non-small cell lung cancer cells.

Non-small cell lung cancer (NSCLC) is the most deadly type of cancer worldwide. Although a number of therapies are used in NSCLC treatment, their therapeutic efficacy remains low. Lenalidomide was originally approved for use in patients with myelodysplastic syndromes, which are associated with 5q deletions, and multiple myeloma. Recently, lenalidomide was investigated as a new NSCLC treatment, and it exerted anticancer effects. However, the primary cellular mechanism of its effects in NSCLC is largely unknown. Therefore, we attempted to elucidate a molecular portrait of lenalidomide-mediated cellular events in NSCLC. Lenalidomide reduced the viability of several NSCLC cell lines in a concentration-dependent manner. In addition, array-based gene expression analysis revealed that lenalidomide regulated the expression of several genes associated with cell survival, apoptosis and development, including BH3-interacting domain death agonist (BID), v-fos FBJ murine osteosarcoma viral oncogene homolog (FOS) and NK2 homeobox1 (NKX2-1). BID and FOS, which are known apoptosis activators, were upregulated by lenalidomide treatment, whereas NKX2-1, which is used as an immunohistochemistry marker for NSCLC, was downregulated. These results provide evidence that lenalidomide directly induces antiproliferative effects by altering the expression of genes associated with cell proliferation and apoptosis.

Sophora japonica extracts accelerates keratinocyte differentiation through miR-181a

BackgroundThe Sophora japonica extracts contain flavonol triglycoside, isoflavonol, coumarone chromone, saponin, triterpene glucoside, phospholipids, alkaloids, amino acids, polysaccharides, and fatty acids. These components have physiological effects such as anti-infertility and anti-cancer activities. This study investigated the regulation of keratinocyte differentiation upon treatment with the S. japonica extracts in keratinocyte and the molecular cell biological mechanism involved.MethodsTo determine whether the S. japonica extracts or troxerutin, which is its main component, regulates keratinocyte differentiation, quantitative real-time polymerase chain reaction (qRT-PCR) was performed on keratinocyte differentiation markers such as keratin 1 (K1), keratin 10 (K10), involucrin, and filaggrin after treatment with the S. japonica extracts. miR-181a knockdown confirmed that keratinocyte differentiation was regulated by increased miR-181a expression upon treatment with the S. japonica extracts or troxerutin.ResultsThe expression of keratinocyte differentiation markers such as K1, K10, involucrin, and filaggrin increased upon treatment with the S. japonica extracts and troxerutin. Furthermore, miR-181a expression, which is known to increase during keratinocyte differentiation, increased upon treatment with the S. japonica extracts and troxerutin. When miR-181a was knocked down, the increased expression of keratinocyte differentiation markers upon treatment with the S. japonica extracts and troxerutin decreased again. Finally, it was confirmed that miR-181a directly regulated and reduced the expression of Notch2, which reduces keratinocyte differentiation, and that the decrease in Notch2 expression by miR-181a regulated keratinocyte differentiation.ConclusionsThese results suggest that the S. japonica extracts or troxerutin accelerates keratinocyte differentiation through miR-181a. This accelerated keratinocyte differentiation was confirmed to have resulted from the regulation of Notch2 expression by miR-181a. The results of this study provide an opportunity to confirm the molecular cell biological mechanism of S. japonica extracts or troxerutin on skin keratinization, and we expected that this study contribute to develop a moisturizing cosmetic material that can strengthen the skin barrier through regulating keratinocyte differentiation.