The failing heart stimulates tumor growth by circulating factors

Background—Heart failure (HF) survival has improved and nowadays many patients with HF die from non-cardiac causes, including cancer. Our aim was to investigate whether a causal relationship exists between HF and the development of cancer. Methods—HF was induced by inflicting large anterior myocardial infarction (MI) in APCmin mice, which are prone to develop precancerous intestinal tumors, and tumor growth was measured. In addition, to rule out hemodynamic impairment, a heterotopic heart transplantation model was employed, where an infarcted or sham-operated heart was transplanted into a recipient mouse, while the native heart was left in situ. After 6 weeks, tumor number, volume, and proliferation were quantified. Candidate secreted proteins were selected because they were previously associated both with (colon) tumor growth and with myocardial production in post-MI proteomic studies. Myocardial gene expression levels of these selected candidates were analyzed, as well as their proliferative effects on HT-29 (colon cancer) cells. We validated these candidates by measuring them in plasma of healthy subjects and HF patients. Finally, we associated the relation between cardiac specific and inflammatory biomarkers and new-onset cancer in a large prospective general population cohort. Results—The presence of failing hearts, both native and heterotopically transplanted, resulted in significantly increased intestinal tumor load of 2.4fold in APCmin mice (all P<0.0001). The severity of left ventricular (LV) dysfunction and fibrotic scar strongly correlated with tumor growth (P=0.002 and P=0.016, respectively). We identified several proteins (including serpinA3 and A1, fibronectin, ceruloplasmin, and PON1) that were elevated in human patients with chronic HF (N=101) compared to healthy subjects (N=180, P<0.001). Functionally, serpinA3 resulted in marked proliferation effects in human colon cancer (HT-29) cells, associated with Akt-S6 phosphorylation. Finally, elevated cardiac and inflammation biomarkers in apparently healthy humans (N=8319), were predictive for new-onset cancer (N=1124), independent from risk factors for cancer (age, smoking status and body mass index). Conclusions—We demonstrate that the presence of HF is associated with enhanced tumor growth and this is independent from hemodynamic impairment and could be due cardiac excreted factors. A diagnosis of HF may therefore be considered a risk factor for incident cancer

Fluorescent fusion protein knockout mediated by anti-GFP nanobody

The use of genetic mutations to study protein functions in vivo is a central paradigm of modern biology. Recent advances in reverse genetics such as RNA interference and morpholinos are widely used to further apply this paradigm. Nevertheless, such systems act upstream of the proteic level, and protein depletion depends on the turnover rate of the existing target proteins. Here we present deGradFP, a genetically encoded method for direct and fast depletion of target green fluorescent protein (GFP) fusions in any eukaryotic genetic system. This method is universal because it relies on an evolutionarily highly conserved eukaryotic function, the ubiquitin pathway. It is traceable, because the GFP tag can be used to monitor the protein knockout. In many cases, it is a ready-to-use solution, as GFP protein-trap stock collections are being generated in Drosophila melanogaster and in Danio rerio