Towards an in vitro fibrogenesis model of human vocal fold scarring.

BACKGROUND: Vocal fold (VF) scarring remains a therapeutic dilemma and challenge in modern laryngology. To facilitate corresponding research, we aimed to establish an in vitro fibrogenesis model employing human VF fibroblasts (hVFF) and the principles of macromolecular crowding (MMC). METHODS: Fibrogenesis was promoted by addition of transforming growth factor-ß1 to standard medium and medium containing inert macromolecules (MMC). Hepatocyte growth factor (HGF) and Botox type A were tested for their antifibrotic properties in various doses. Experiments were analyzed with respect to the biosynthesis of collagen, fibronectin, and α-smooth muscle actin using immunofluorescence, silver stain and western blot. RESULTS: MMC led to favourable enhanced deposition of collagen and other extracellular matrix components, reflecting fibrotic conditions. Low doses of HGF were able to dampen profibrotic effects. This could not be observed for higher HGF concentrations. Botox type A did not show any effects. CONCLUSION: Based on the principles of MMC we could successfully establish a laryngeal fibrogenesis model employing hVFF. Our finding of dose-dependent HGF effects is important before going into clinical trials in humans and has never been shown before. Our model provides a novel option to screen various potential antifibrotic compounds under standardized conditions in a short time.

Mesoderm-specific transcript (MEST) is a negative regulator of human adipocyte differentiation.

BACKGROUND: A growing body of evidence suggests that many downstream pathologies of obesity are amplified or even initiated by molecular changes within the white adipose tissue (WAT). Such changes are the result of an excessive expansion of individual white adipocytes and could potentially be ameliorated via an increase in de novo adipocyte recruitment (adipogenesis). Mesoderm-specific transcript (MEST) is a protein with a putative yet unidentified enzymatic function and has previously been shown to correlate with adiposity and adipocyte size in mouse. OBJECTIVES: This study analysed WAT samples and employed a cell model of adipogenesis to characterise MEST expression and function in human. METHODS AND RESULTS: MEST mRNA and protein levels increased during adipocyte differentiation of human multipotent adipose-derived stem cells. Further, obese individuals displayed significantly higher MEST levels in WAT compared with normal-weight subjects, and MEST was significantly correlated with adipocyte volume. In striking contrast to previous mouse studies, knockdown of MEST enhanced human adipocyte differentiation, most likely via a significant promotion of peroxisome proliferator-activated receptor signalling, glycolysis and fatty acid biosynthesis pathways at early stages. Correspondingly, overexpression of MEST impaired adipogenesis. We further found that silencing of MEST fully substitutes for the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX) as an inducer of adipogenesis. Accordingly, phosphorylation of the pro-adipogenic transcription factors cyclic AMP responsive element binding protein (CREB) and activating transcription factor 1 (ATF1) were highly increased on MEST knockdown. CONCLUSIONS: Although we found a similar association between MEST and adiposity as previously described for mouse, our functional analyses suggest that MEST acts as an inhibitor of human adipogenesis, contrary to previous murine studies. We have further established a novel link between MEST and CREB/ATF1 that could be of general relevance in regulation of metabolism, in particular obesity-associated diseases.

MiR-200a regulates epithelial to mesenchymal transition-related gene expression and determines prognosis in colorectal cancer patients.

BACKGROUND: MicroRNAs (miRNAs) regulate the biological properties of colorectal cancer (CRC) cells and might serve as potential prognostic factors and therapeutic targets. In this study, we therefore globally profiled miRNAs associated with E-cadherin expression in CRC cells in an attempt to identify miRNAs that are associated with aggressive clinical course in CRC patients. METHODS: Two CRC cell lines (Caco-2 and HRT-18) with different E-cadherin expression pattern were profiled for differences in abundance for more than 1000 human miRNAs using microarray technology. One of the most differentially expressed miRNAs, miR-200a was evaluated for its prognostic role in a cohort of 111 patients and independently validated in 217 patients of the Cancer Genome Atlas data set. To further characterise the biological role of miR-200a expression in CRC, in vitro miR-200a inhibition and overexpression were performed and the effects on cellular growth, apoptosis and epithelial-mesenchymal transition (EMT)-related gene expression were explored. RESULTS: In situ hybridisation specifically localised miR-200a in CRC cells. In both cohorts, a low miR-200a expression was associated with poor survival (P<0.05). Multivariate Cox regression analysis identified low levels of miR-200a expression as an independent prognostic factor with respect to cancer-specific survival (HR=2.04, CI=1.28-3.25, P<0.002). Gain and loss of function assays for miR-200a in vitro led to a significantly differential and converse expression of EMT-related genes (P<0.001.) A low expression of miR-200a was also observed in cancer stem cell-enriched spheroid growth conditions (P<0.05). CONCLUSIONS: In conclusion, our data suggest that low miR-200a expression is associated with poor prognosis in CRC patients. MiR-200a has a regulatory effect on EMT and is associated with cancer stem cell properties in CRC.