SOX2 and cancer: current research and its implications in the clinic

SOX2 is a gene that encodes for a transcription factor belonging to the SOX gene family and contains a high-mobility group (HMG) domain, which permits highly specific DNA binding. Consequently, SOX2 functions as an activator or suppressor of gene transcription. SOX2 has been described as an essential embryonic stem cell gene and moreover, a necessary factor for induced cellular reprogramming. SOX2 research has only recently switched focus from embryogenesis and development to SOX2’s function in disease. Particularly, the role of SOX2 in cancer pathogenesis has become of interest in the field. To date, studies have shown SOX2 to be amplified in various cancer types and affect cancer cell physiology via involvement in complicated cell signaling and protein-protein interactions. Recent reviews in this field have highlighted SOX2 in mammalian physiology, development and pathology. In this review, we comprehensively compile what is known to date about SOX2’s involvement in cancer biology, focusing on the most recent findings in the fields of cellular signaling and cancer stem cells. Lastly, we underscore the role of SOX2 in the clinic and highlight new findings, which may provide novel clinical applications for SOX2 as a prognostic marker, indicator of metastasis, biomarker or potential therapeutic target in some cancer types

Functional analysis of SOX2 in melanocyte development and melanoma pathogenesis

Malignant melanoma remains the most deadly form of skin cancer due to its quick metastatic spread and the development of resistance to available treatment. The cause of melanoma is still under investigation but environmental factors, such as ultraviolet radiation, have been associated with the initiation of melanoma. Moreover, studies have revealed that the melanocytic lineage is predisposed to malignant transformation due to its developmental program. Melanocytes are derived from the embryonic neural crest, which utilizes processes such as the epithelial-to-mesenchymal transition (EMT) during their normal development to spatially migrate and complete terminal differentiation. Therefore, recent work in the field of melanoma has focused on investigating embryonic and neural crest-related genes since they may be reactivated during melanomagenesis and metastatic spread. To date, limited studies have suggested an important role of the embryonic stem cell marker, sex determining region Y-box 2 (SOX2), in melanoma; however a lack of detailed analyses and understanding of its function remains. In this study, SOX2 was found to be highly expressed in primary melanomas compared to melanocytic nevi. Additionally, using fluorescence in situ hybridization analysis, genomic SOX2 was found to be significantly amplified in both primary melanomas and metastatic melanomas compared to melanocytic nevi. Gain-of-function studies revealed that melanoma cells lost differentiation marker expression upon SOX2 overexpression in vitro. The dedifferentiated phenotype displayed can be in part explained by SOX2 binding to the promoter region of the microphthalmia-associated transcription factor-M (MITF-M), thereby repressing its transcription. Additionally, SOX2 was shown to be required for melanoma cell migration and invasion in vitro. Invasion-related EMT markers were upmodulated upon SOX2 overexpression and immunohistochemical analysis revealed high SOX2 expression in deep regions of primary melanomas and in stroma-infiltrating melanoma cells. In vitro enhanced SOX2 expression could be induced by TGF-β, indicating TGF-β signaling as an upstream regulator of SOX2 expression in melanoma. This study proposes that TGF-β1 induces SOX2 expression, which may lead to melanoma progression by: i) SOX2 binding and repressing the MITF-M promoter, which may influence the dedifferentiation of human melanoma cells, and ii) SOX2 inducing high expression of ZEB1 and TWIST1, which promotes a mesenchymal phenotype. In line with the described phenotypic alterations, this work revealed that SOX2 enhances melanoma cell migration and invasion and depletion of this transcription factor results in loss of cellular motility. Therefore, I identified SOX2 as a key player in the complex molecular network that governs invasion-related processes and I revealed a role for SOX2 as an invasion-related marker with potential clinical application

A dominant negative zebrafish Ahr2 partially protects developing zebrafish from dioxin toxicity.

The toxicity by 2,3,7,8 tetrachlorodibenzo-p-dioxin (TCDD) is thought to be caused by activation of the aryl hydrocarbon receptor (AHR). However, our understanding of how AHR activation by TCDD leads to toxic effects is poor. Ideally we would like to manipulate AHR activity in specific tissues and at specific times. One route to this is expressing dominant negative AHRs (dnAHRs). This work describes the construction and characterization of dominant negative forms of the zebrafish Ahr2 in which the C-terminal transactivation domain was either removed, or replaced with the inhibitory domain from the Drosophila engrailed repressor protein. One of these dnAhr2s was selected for expression from the ubiquitously active e2fα promoter in transgenic zebrafish. We found that these transgenic zebrafish expressing dnAhr2 had reduced TCDD induction of the Ahr2 target gene cyp1a, as measured by 7-ethoxyresorufin-O-deethylase activity. Furthermore, the cardiotoxicity produced by TCDD, pericardial edema, heart malformation, and reduced blood flow, were all mitigated in the zebrafish expressing the dnAhr2. These results provide in vivo proof-of-principle results demonstrating the effectiveness of dnAHRs in manipulating AHR activity in vivo, and demonstrating that this approach can be a means for blocking TCDD toxicity

Green extraction of phenolics and flavonoids from black mulberry fruit using natural deep eutectic solvents: optimization and surface morphology

Abstract This study deployed ultrasonic-assisted extraction (UAE), combined with natural deep eutectic solvents (NADES), to extract phenolics and flavonoids from the black mulberry fruit, and the antioxidant activity was examined. The extraction yields of NADES-based UAE were assessed based on the yields of phenolics and flavonoids extracted from the black mulberry fruit. This study selected the molar ratios of hydrogen bond acceptors (HBA) and hydrogen bond donors HBD at 1:2 from previous studies. Choline chloride-lactic acid showed the highest solubility with phenolics and flavonoids among NADES systems. One-factor experiments evaluated the effect of UAE conditions (liquid-to-solid ratio (LSR), water content in NADES, temperature, and time) on TPC, TFC, and antioxidant activity. The suitable NADES-based UAE conditions for extracting phenolics and flavonoids from the black mulberry fruit were 60 ml/g of LSR, 40% water content, 70 °C, and 15 min. Response surface methodology with the Box-Behnken design model optimized the NADES-based UAE process based on response (TPC, TFC, ABTS, OH, and DPPH). The optimal conditions for the NADES-based UAE process were 70 ml/g of LSR, 38.9% water content in NADES, 67.9 °C, and 24.2 min of extraction time. The predicted values of the Box-Behnken design were compatible with the experimental results. Moreover, scanning electron microscopy (SEM) was used to survey the surface of black mulberry fruit with and without sonication. SEM can assist in demonstrating the destructive effect of NADES and ultrasonic waves on material surfaces. SEM findings indicated the high surface destruction capacity of NADES, which partially contributed to a superior extraction yield of NADES than conventional organic solvents. The study proposes an efficient and green method for extracting bioactive compounds from black mulberry fruits. The black mulberry fruit extracts can be applied to meat preservation and beverages with high antioxidants

NF1 loss induces senescence during human melanocyte differentiation in an iPSC-based model

Neurofibromatosis type 1 (NF1) is a frequent genetic disease leading to the development of Schwann cell-derived neurofibromas or melanocytic lesions called cafe-au-lait macules (CALMs). The molecular mechanisms involved in CALMs formation remain largely unknown. In this report, we show for the first time pathophysiological mechanisms of abnormal melanocyte differentiation in a human NF1(+/-)-induced pluripotent stem cell (iPSC)-based model. We demonstrate that NF1 patient-derived fibroblasts can be successfully reprogrammed in NF1(+/-) iPSCs with active RAS signaling and that NF1 loss induces senescence during melanocyte differentiation as well as in patient's-derived CALMs, revealing a new role for NF1 in the melanocyte lineage