Comparison of Transparency and Shrinkage During Clearing of Insect Brains Using Media With Tunable Refractive Index.

Improvement of imaging quality has the potential to visualize previously unseen building blocks of the brain and is therefore one of the great challenges in neuroscience. Rapid development of new tissue clearing techniques in recent years have attempted to solve imaging compromises in thick brain samples, particularly for high resolution optical microscopy, where the clearing medium needs to match the high refractive index of the objective immersion medium. These problems are exacerbated in insect tissue, where numerous (initially air-filled) tracheal tubes branching throughout the brain increase the scattering of light. To date, surprisingly few studies have systematically quantified the benefits of such clearing methods using objective transparency and tissue shrinkage measurements. In this study we compare a traditional and widely used insect clearing medium, methyl salicylate combined with permanent mounting in Permount ("MS/P") with several more recently applied clearing media that offer tunable refractive index (n): 2,2'-thiodiethanol (TDE), "SeeDB2" (in variants SeeDB2S and SeeDB2G matched to oil and glycerol immersion, n = 1.52 and 1.47, respectively) and Rapiclear (also with n = 1.52 and 1.47). We measured transparency and tissue shrinkage by comparing freshly dissected brains with cleared brains from dipteran flies, with or without addition of vacuum or ethanol pre-treatments (dehydration and rehydration) to evacuate air from the tracheal system. The results show that ethanol pre-treatment is very effective for improving transparency, regardless of the subsequent clearing medium, while vacuum treatment offers little measurable benefit. Ethanol pre-treated SeeDB2G and Rapiclear brains show much less shrinkage than using the traditional MS/P method. Furthermore, at lower refractive index, closer to that of glycerol immersion, these recently developed media offer outstanding transparency compared to TDE and MS/P. Rapiclear protocols were less laborious compared to SeeDB2, but both offer sufficient transparency and refractive index tunability to permit super-resolution imaging of local volumes in whole mount brains from large insects, and even light-sheet microscopy. Although long-term permanency of Rapiclear stored samples remains to be established, our samples still showed good preservation of fluorescence after storage for more than a year at room temperature.

Gas6-Axl signaling in presence of Sunitinib is enhanced, diversified and sustained in renal tumor cells, resulting in tumor-progressive advantages.

Clear Cell Renal Cell Carcinoma (CCRCC) is a lethal cancer with bad prognosis due to development of chemoresistance and recurrence of more aggressive tumors. Investigation of Gas6-mediated Axl signaling in CCRCC and endothelial cells reveals a Sunitinib resistant Gas6-Axl signaling that is sustained and enhanced and specifically triggers downstream AKT and PRAS40 activation in an intensified manner. Gas6-induced Axl signaling in presence of Sunitinib is also diversified displaying onset of Axl-dependent EGFR and METR activation and activation of classical MAPK pathways. Gas6+Sunitinib-adapted CCRCC cells present increased viability and decreased apoptosis and enhanced production of the multi-tumorigenic Osteopontin (OPN) and of one of its activator matrix metalloproteinase-7. Axl activity is necessary for CCRCC cell sphere formation and the ability of the cells to attach after non-adhesive growth. In addition, Gas6+Sunitinib-adapted CCRCC cells displayed enhanced migration and sphere formation, both mechanisms being Axl and OPN dependent. Altogether, this suggests that Sunitinib while targeting endothelial cells and tumor angiogenesis, simultaneously provides protumorigenic effects due to a constitutively, intensified and divergent Gas6-Axl system. IMPLICATIONS: Gas6-mediated Axl signaling, which is enhanced and diversified in the presence of Sunitinib possibly contributes to acquired chemoresistance, recurrence of aggressive disease and metastasis of CCRCC tumors. Therefore, combinatorial Axl-targeted therapy might be beneficial for CCRCC patients intended for Sunitinib treatment.

The miR(21/10b) ratio as a prognostic marker in clear cell renal cell carcinoma.

PURPOSE: Clear cell renal cell carcinoma (ccRCC) is the most common type of cancer in the adult kidney, and the prognosis of metastatic ccRCC remains poor with high mortality. In ccRCC, microRNAs (miRs) differentially expressed in tumour tissue have been identified and have been proposed to predict prognosis. The purpose of this study was to evaluate candidate miR markers identified from analysis of The Cancer Genome Atlas (TCGA) datasets in a large RCC cohort and to elucidate whether a ratio of miRs provided additional prognostic information. EXPERIMENTAL DESIGN: Deep sequencing data from TCGA datasets were analysed using biostatistical methods to identify candidate miRs that correlate with factors such as survival and stage of disease. Candidate miRs were analysed by reverse transcription and quantitative polymerase chain reaction (RT-qPCR) in a cohort of 198 RCC tumours (ccRCC, n=152) and 50 normal kidney samples. RESULTS: Four candidate miRs (miR-10b, miR-21, miR-101 and miR-223) were selected from the TCGA analysis and analysed in our cohort. Of these, miR-21 and miR-10b were differentially expressed in RCC subtypes and in ccRCC nuclear grades. Individually, the two miRs demonstrated a non-significant trend to correlate with survival. Importantly, the ratio of miR-21/miR10b (miR(21/10b)) correlated significantly with disease severity and survival, a high miR(21/10b) being associated with poor prognosis (P=0.0095). In particular, the miR(21/10b) was found to be an independent prognostic factor in metastasis-free patients (P=0.016; confidence interval (CI) 1.201-5.736). CONCLUSIONS: We have shown that the miR(21/10b) ratio is an independent prognostic factor for M0 ccRCC patients, which could be useful to identify high-risk M0 patients who could benefit from increased surveillance.