The VTI1A-TCF4 colon cancer fusion protein is a dominant negative regulator of Wnt signaling and is transcriptionally regulated by intestinal homeodomain factor CDX2

<div><p>Sequencing of primary colorectal tumors has identified a gene fusion in approximately 3% of colorectal cancer patients of the <i>VTI1A</i> and <i>TCF7L2</i> genes, encoding a VTI1A-TCF4 fusion protein containing a truncated TCF4. As dysregulation of the Wnt signaling pathway is associated with colorectal cancer development and progression, the functional properties and transcriptional regulation of the VTI1A-TCF4 fusion protein may also play a role in these processes. Functional characteristics of the VTI1A-TCF4 fusion protein in Wnt signaling were analyzed in NCI-H508 and LS174T colon cancer cell lines. The NCI-H508 cell line, containing the <i>VTI1A</i>-<i>TCF7L2</i> fusion gene, showed no active Wnt signaling, and overexpression of the VTI1A-TCF4 fusion protein in LS174T cells along with a Wnt signaling luciferase reporter plasmid showed inhibition of activity. The transcriptional regulation of the <i>VTI1A-TCF4</i> fusion gene was investigated in LS174T cells where the activity of the <i>VTI1A</i> promoter was compared to that of the <i>TCF7L2</i> promoter, and the transcription factor CDX2 was analyzed for gene regulatory activity of the <i>VTI1A</i> promoter through luciferase reporter gene assay using colon cancer cell lines as a model. Transfection of LS174T cells showed that the <i>VTI1A</i> promoter is highly active compared to the <i>TCF7L2</i> promoter, and that CDX2 activates transcription of <i>VTI1A</i>. These results suggest that the VTI1A-TCF4 fusion protein is a dominant negative regulator of the Wnt signaling pathway, and that transcription of <i>VTI1A</i> is activated by CDX2.</p></div

A systematic review of mechanisms of change in mindfulness-based cognitive therapy in the treatment of recurrent major depressive disorder

AbstractBackgroundThe investigation of treatment mechanisms in randomized controlled trials has considerable clinical and theoretical relevance. Despite the empirical support for the effect of mindfulness-based cognitive therapy (MBCT) in the treatment of recurrent major depressive disorder (MDD), the specific mechanisms by which MBCT leads to therapeutic change remain unclear.ObjectiveBy means of a systematic review we evaluate how the field is progressing in its empirical investigation of mechanisms of change in MBCT for recurrent MDD.MethodTo identify relevant studies, a systematic search was conducted. Studies were coded and ranked for quality.ResultsThe search produced 476 articles, of which 23 were included. In line with the theoretical premise, 12 studies found that alterations in mindfulness, rumination, worry, compassion, or meta-awareness were associated with, predicted or mediated MBCT's effect on treatment outcome. In addition, preliminary studies indicated that alterations in attention, memory specificity, self-discrepancy, emotional reactivity and momentary positive and negative affect might play a role in how MBCT exerts its clinical effects.ConclusionThe results suggest that MBCT could work through some of the MBCT model's theoretically predicted mechanisms. However, there is a need for more rigorous designs that can assess greater levels of causal specificity

Colorectal cancer-associated SNP rs17042479 is involved in the regulation of NAF1 promoter activity

A novel risk locus at 4q32.2, located between the Nuclear Assembly Factor 1 (NAF1) and Follistatin Like 5 (FSTL5) genes, was associated with increased risk of developing colorectal cancer (CRC), with SNP rs17042479 being the most associated. However, the link between CRC development and the risk locus at 4q32.2 is unknown. We investigated the promoter activity of NAF1 and FSTL5 and analyzed the risk locus at 4q32.2 as gene regulatory region. Our results showed that the activity of the FSTL5 promoter was low compared to the NAF1 promoter. Analyses of the NAF1 promoter in conjunction with the region containing the risk locus at 4q32.2 showed that the region functions as gene regulatory region with repressor activity on NAF1 promoter activity. The SNP rs17042479(G) increased the repressor effect of the region. CRC patients’ biopsies were genotyped for SNP rs17042479(A/G), and NAF1 expression profiles were examined. We found an association between SNP rs17042479(G), cancer stage and tumor location. Additionally, patients with SNP rs17042479(G) showed lower NAF1 expression in comparison to patients with SNP rs17042479(A) in tumor tissue and the NAF1 expression in tumor tissue was lower compared to healthy tissue. The results in the study imply that reduced NAF1 expression in the tumor contribute to a more aggressive phenotype. Furthermore, this study suggests that the SNP rs17042479(G) change the expression of NAF1 and thereby increases the risk of developing CRC

Analytical variables influencing the performance of a miRNA based laboratory assay for prediction of relapse in stage I non-small cell lung cancer (NSCLC)

<p>Abstract</p> <p>Background</p> <p>Laboratory assays are needed for early stage non-small lung cancer (NSCLC) that can link molecular and clinical heterogeneity to predict relapse after surgical resection. We technically validated two miRNA assays for prediction of relapse in NSCLC. Total RNA from seventy-five formalin-fixed and paraffin-embedded (FFPE) specimens was extracted, labeled and hybridized to Affymetrix miRNA arrays using different RNA input amounts, ATP-mix dilutions, array lots and RNA extraction- and labeling methods in a total of 166 hybridizations. Two combinations of RNA extraction- and labeling methods (assays I and II) were applied to a cohort of 68 early stage NSCLC patients.</p> <p>Results</p> <p>RNA input amount and RNA extraction- and labeling methods affected signal intensity and the number of detected probes and probe sets, and caused large variation, whereas different ATP-mix dilutions and array lots did not. Leave-one-out accuracies for prediction of relapse were 63% and 73% for the two assays. Prognosticator calls ("no recurrence" or "recurrence") were consistent, independent on RNA amount, ATP-mix dilution, array lots and RNA extraction method. The calls were not robust to changes in labeling method.</p> <p>Conclusions</p> <p>In this study, we demonstrate that some analytical conditions such as RNA extraction- and labeling methods are important for the variation in assay performance whereas others are not. Thus, careful optimization that address all analytical steps and variables can improve the accuracy of prediction and facilitate the introduction of microRNA arrays in the clinic for prediction of relapse in stage I non-small cell lung cancer (NSCLC).</p

Validity of Thermal Ramping Assays Used to Assess Thermal Tolerance in Arthropods

Proper assessment of environmental resistance of animals is critical for the ability of researchers to understand how variation in environmental conditions influence population and species abundance. This is also the case for studies of upper thermal limits in insects, where researchers studying animals under laboratory conditions must select appropriate methodology on which conclusions can be drawn. Ideally these methods should precisely estimate the trait of interest and also be biological meaningful. In an attempt to develop such tests it has been proposed that thermal ramping assays are useful assays for small insects because they incorporate an ecologically relevant gradual temperature change. However, recent model-based papers have suggested that estimates of thermal resistance may be strongly confounded by simultaneous starvation and dehydration stress. In the present study we empirically test these model predictions using two sets of independent experiments. We clearly demonstrate that results from ramping assays of small insects (Drosophila melanogaster) are not compromised by starvation- or dehydration-stress. Firstly we show that the mild disturbance of water and energy balance of D. melanogaster experienced during the ramping tests does not confound heat tolerance estimates. Secondly we show that flies pre-exposed to starvation and dehydration have “normal” heat tolerance and that resistance to heat stress is independent of the energetic and water status of the flies. On the basis of our results we discuss the assumptions used in recent model papers and present arguments as to why the ramping assay is both a valid and ecologically relevant way to measure thermal resistance in insects