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Reprogramming of mRNA translation has a key role in cancer development and drug resistance.sup.1. However, the molecular mechanisms that are involved in this process remain poorly understood. Wobble tRNA modifications are required for specific codon decoding during translation.sup.2,3. Here we show, in humans, that the enzymes that catalyse modifications of wobble uridine 34 (U.sub.34) tRNA (U.sub.34 enzymes) are key players of the protein synthesis rewiring that is induced by the transformation driven by the BRAF.sup.V600E oncogene and by resistance to targeted therapy in melanoma. We show that BRAF.sup.V600E-expressing melanoma cells are dependent on U.sub.34 enzymes for survival, and that concurrent inhibition of MAPK signalling and ELP3 or CTU1 and/or CTU2 synergizes to kill melanoma cells. Activation of the PI3K signalling pathway, one of the most common mechanisms of acquired resistance to MAPK therapeutic agents, markedly increases the expression of U.sub.34 enzymes. Mechanistically, U.sub.34 enzymes promote glycolysis in melanoma cells through the direct, codon-dependent, regulation of the translation of HIF1A mRNA and the maintenance of high levels of HIF1[alpha] protein. Therefore, the acquired resistance to anti-BRAF therapy is associated with high levels of U.sub.34 enzymes and HIF1[alpha]. Together, these results demonstrate that U.sub.34 enzymes promote the survival and resistance to therapy of melanoma cells by regulating specific mRNA translation. Enzymes that catalyse modifications of wobble uridine 34 tRNA are essential for the survival of melanoma cells that rely on HIF1[alpha]-dependent metabolism through codon-dependent regulation of the translation of HIF1A mRNA., Author(s): Francesca Rapino [sup.1] [sup.2] , Sylvain Delaunay [sup.1] [sup.2] , Florian Rambow [sup.3] [sup.4] , Zhaoli Zhou [sup.1] [sup.2] , Lars Tharun [sup.5] , Pascal De Tullio [sup.6] , [...]

Author(s): Francesca Rapino [sup.1] [sup.2] , Sylvain Delaunay [sup.1] [sup.2] , Florian Rambow [sup.3] [sup.4] , Zhaoli Zhou [sup.1] [sup.2] , Lars Tharun [sup.5] , Pascal De Tullio [sup.6] , [...]

Highlights • A novel recombinant soluble peptide fragment (rhFzd7) was generated to antagonize Fzd7/β-catenin pathway. • rhFzd7 demonstrated specificity and affinity to Wnt3a. • rhFzd7 exhibited remarkably anti-tumor and anti-angiogenesis activity against TNBC. • When used in combination with standard chemotherapeutic agents, rhFzd7 sensitized TNBC to the drugs significantly. • The design of recombinant Fzd7 protein provides a safe and effective candidate for clinical treatment of TNBC. Abstract Triple negative breast cancer (TNBC) is one of the most difficult malignancy to treat due to a lack of targeted therapy. Studies have demonstrated that the activation of Wnt/β-catenin signaling was preferentially found in TNBC. Frizzled-7 (Fzd7), one of the Wnt receptors, was significantly up-regulated in TNBC and modulated TNBC tumorigenesis through the Wnt signaling pathway, indicating Fzd7 is a biomarker and a potential therapeutic target for TNBC. Here, we designed a recombinant soluble peptide fragment (rhFzd7) to antagonize Fzd7 by competitively binding with Wnt ligands. We demonstrated the ability of rhFzd7 to bind to its ligand, Wnt3a, and monitored the kinetic process using a Biacore X100 system. In addition, the anti-tumor and anti-angiogenic activity of rhFzd7 were studied in vitro and in vivo. Results showed that the purified rhFzd7 pulled down Wnt3a from MDA-MB-231 cells and exhibited high affinity with Wnt3a (KD: 3.41 × 10−8 M). The data in vitro revealed that rhFzd7 inhibited proliferation and invasion of TNBC cells, and induced apoptosis of TNBC cells effectively. The anti-angiogenic assay indicated that rhFzd7 repressed TNBC angiogenesis in vitro and in vivo. Furthermore, the study in vivo showed that rhFzd7 could sensitize TNBC cells to the anti-tumor effect of Docetaxel. In conclusion, the generation of rhFzd7 lays foundation for the screening of anti-Fzd7 antibody, and this novel design provides an effective candidate for the clinical treatment of TNBC. [ABSTRACT FROM AUTHOR]

Bevacizumab, a monoclonal antibody targeting vascular endothelial growth factor A (VEGF-A), was used in combination with traditional chemotherapy as the first line treatment for metastatic colorectal cancer (mCRC), non-small cell lung cancer (NSCLC) and advanced ovarian cancer. However, it shows limited efficacy for human triple-negative breast cancer (TNBC). Bevacizumab shows potent anti-angiogenesis activity, meanwhile, it also increases invasive and metastatic properties of TNBC cells by activiting Wnt/β-Catenin pathway. To overcome this problem, and fully utilize its potency against cancer, further synergistic strategy is recommended to be developed, especially the concurrent use with those Wnt-targeting agents. Here, by screening a small library of traditional Chinese medicine, we identified a Chinese herb derived Oxymatrine, which could target Wnt/β-Catenin signaling and compromise the oncogenic effects of Bevacizumab. Bevacizumab was validated to induce epithelial-mesenchymal cell transformation (EMT) and cancer stem-like properties of TNBC cells in hypoxia/nutritional stress environment. On the contrary, Oxymatrine reversed the EMT phenotype and depleted the subpopulation of TNBC stem cells induced by Bevacizumab. Oxymatrine enhanced the anti-tumor effects of Bevacizumab in vivo , and holded the potential of reducing the risk of relapse and metastasis by impairing the self-renewal ability of TNBC stem cells. The underlying mechanism was elucidated: Bevacizumab stimulated Wnt/β-Catenin signaling pathway, and Oxymatrine could compromise this effect. On this foundation, factoring into the satisfactory anti-angiogenic activity and low toxicity, Oxymatrine is a good candidate for the synergistic therapy together with Bevacizumab for the treatment of TNBC., Competing Interests: None.