Anti-SRSF1 (aa 165-194) polyclonal antibody

Tumor growth relies on oxygen and blood supply depending on neo-vascularization. This process is mediated by the Vascular Endothelial Growth Factor (VEGF) in many tumors. This paradigm has led to the development of specific therapeutic approaches targeting VEGF or its receptors. Despite their promising effects, these strategies have not improved overall survival of patients suffering from different cancers compared to standard therapies. We hypothesized that the existence of anti-angiogenic forms of VEGF VEGFxxxb which are still present in many tumors limit the therapeutic effects of the anti-VEGF antibodies bevacizumab/Avastin (BVZ). To test this hypothesis, we generated renal cell carcinoma cells (RCC) expressing VEGF165b. The incidence of tumors xenografts generated in nude mice and their growth were inferior to those obtained with control cells. Whereas BVZ had no effect on control tumors, it slowed-down the growth of tumor generated with VEGF165b expressing cells. A prophylactic immunization against the domain discriminating VEGF from VEGFxxxb isoforms inhibited the growth of tumor generated with two different syngenic tumor cell lines (melanoma (B16 cells) and RCC (RENCA cells)). Purified immunoglobulins from immunized mice also slowed-down tumor growth of human RCC xenografts in nude mice, producing a potent effect compared to BVZ in this model. Furthermore, down-regulating the serine-arginine-rich splicing factor 1 (SRSF1) or masking SRSF1 binding sites by 2'O-Methyl RNA resulted in the increase of the VEGFxxxb/VEGF ratio. Therefore, a vaccine approach, specific antibodies against pro-angiogenic forms of VEGF, or increasing the VEGFxxxb/VEGF ratio may represent new prophylactic or pro-active anti-cancer strategies.

Characterization of RNA-binding protein interactions with RNA became inevitable to properly understand the cellular mechanisms involved in gene expression regulation. Structural investigations bring information at the atomic level on these interactions and complementary methods such as Isothermal Titration Calorimetry (ITC) and Surface Plasmon Resonance (SPR) are commonly used to quantify the affinity of these RNA-protein complexes and evaluate the effect of mutations affecting these interactions. The switchSENSE technology has recently been developed and already successfully used to investigate protein interactions with different types of binding partners (DNA, protein/peptide or even small molecules). In this study, we show that this method is also well suited to study RNA binding proteins (RBPs). We could successfully investigate the binding to RNA of three different RBPs (Fox-1, SRSF1 and Tra2-beta 1) and obtained K-D values very close to the ones determined previously by SPR or ITC for these complexes. These results show that the switchSENSE technology can be used as an alternative method to study protein-RNA interactions with KD values in the low micromolar (10(-6)) to nanomolar (10(-7)-10(-9)) and probably picomolar (10(-19)-10(-12)) range. The absence of labelling requirement for the analyte molecules and the use of very low amounts of protein and RNA molecules make the switchSENSE approach very attractive compared to other methods. Finally, we discuss about the potential of this approach in obtaining more sophisticated information such as structural conformational changes upon RBP binding to RNA. (C) 2017 Elsevier Inc. All rights reserved.