Interplay of SOX transcription factors and microRNAs in the brain under physiological and pathological conditions

Precise tuning of gene expression,accomplished by regulato ry networks of transcription factors,epigenetic modifiers,and microRNAs,is crucial for the proper neural development and function of the brain cells.The SOX transcription factors are involved in regulating diverse cellular processes during embryonic and adult neurogenesis,such as maintaining the cell stemness,cell prolife ration,cell fate decisions,and terminal diffe rentiation into neurons and glial cells.MicroRNAs represent a class of small non-coding RNAs that play important roles in the regulation of gene expression.Together with other gene regulatory factors,microRNAs regulate different processes during neurogenesis and orchestrate the spatial and temporal expression important for neurodevelopment.The emerging data point to a complex regulatory network between SOX transcription factors and microRNAs that govern distinct cellular activities in the developing and adult brain.Deregulated SOX/mic roRNA interplay in signaling pathways that influence the homeostasis and plasticity in the brain has been revealed in various brain pathologies,including neurodegenerative disorders,traumatic brain injury,and cancer.Therapeutic strategies that target SOX/microRNA interplay have emerged in recent years as a promising tool to target neural tissue regeneration and enhance neuro restoration.N umerous studies have confirmed complex intera ctions between microRNAs and SOX-specific mRNAs regulating key features of glioblastoma.Keeping in mind the crucial roles of SOX genes and microRNAs in neural development,we focus this review on SOX/microRNAs interplay in the brain during development and adulthood in physiological and pathological conditions.Special focus was made on their interplay in brain pathologies to summarize current knowledge and highlight potential future development of molecular therapies.

Retinoic acid affects basic cellular processes and SOX2 and SOX18 expression in breast carcinoma cells

Genetic and molecular heterogeneity,together with intrinsic and acquired resistance to therapy,represent the major obstacles to the successful treatment of different types of breast carcinoma.Increasing evidence demonstrates that SOX transcription factors in breast carcinomas could act both as oncogenes and tumor suppressors and have been associated with tumor stage and grade,poor prognosis,and therapy resistance.Both SOX2 and SOX18 overexpression has been correlated with poor prognosis in breast carcinomas,and these genes are recognized as potential antitumor targets.Our aim was to evaluate the effect of retinoic acid(RA),a well-known cyto-differentiating agent,on breast carcinoma cells in vitro and to investigate the potential of RA treatment to modify the expression of SOX2 and SOX18 genes.By applying various experimental approaches,we evaluated the effect of RA on basic cellular processes in SK-BR-3 and MCF7 breast carcinoma cell lines.We have shown that RA inhibits cell growth,reduces the number of Ki-67 positive cells,and causes cell-cycle arrest.RA effect was more prominent in SK-BR-3 cell line that lacks SOX2 expression,including a higher decrease in cell viability,reduction in colony formation,and significant remodeling of cellular structure.We have shown that RA treatment led to the downregulation of SOX2 expression in MCF7 cells and to the reduction of SOX18 expression in both cell lines.By functional analysis,we showed that the anti-proliferative effect of RA in both cell lines was not based on the activity of stemness marker SOX2,pointing to a SOX2-independent mechanism of action.The ability of RA to reduce SOX2/SOX18 expression raises the possibility that these genes can be used as biomarkers to distinguish RA-responders from non-responders.Together,our study shows that the response of breast carcinoma cell lines to RA treatment may vary,highlighting that the development of RA-based therapy should consider differences in breast carcinoma subtypes.