Aberrant activation of anaplastic lymphoma kinase (ALK) has been described in a range of human cancers, including non-small cell lung cancer and neuroblastoma (Hallberg and Palmer, 2013). Vertebrate ALK has been considered to be an orphan receptor and the identity of the ALK ligand(s) is a critical issue. Here we show that FAM150A and FAM150B are potent ligands for human ALK that bind to the extracellular domain of ALK and in addition to activation of wild-type ALK are able to drive 'superactivation' of activated ALK mutants from neuroblastoma. In conclusion, our data show that ALK is robustly activated by the FAM150A/B ligands and provide an opportunity to develop ALK-targeted therapies in situations where ALK is overexpressed/activated or mutated in the context of the full length receptor.DOI: http://dx.doi.org/10.7554/eLife.09811.001

An in vitro selection procedure was used to select RNase P ribozyme variants that efficiently cleaved the sequence of the mRNA encoding thymidine kinase of herpes simplex virus 1. Of the 45 selected variants sequenced, 25 ribozymes carried a common mutation at nucleotides 224 and 225 of RNase P catalytic RNA from Escherichia coli (G 224 G 225 3 AA). These selected ribozymes exhibited at least 10 times higher cleavage efficiency (k cat /K m ) than that derived from the wild type ribozyme. Our results suggest that the mutated A 224 A 225 are in close proximity to the substrate and enhance substrate binding of the ribozyme. When these ribozyme variants were expressed in herpes simplex virus 1-infected cells, the levels of thymidine kinase mRNA and protein were reduced by 95-99%. Our study provides the first direct evidence that RNase P ribozyme variants isolated by the selection procedure can be used for the construction of gene-targeting ribozymes that are highly effective in tissue culture. These results demonstrate the potential for using RNase P ribozymes as gene-targeting agents against any mRNA sequences, and using the selection procedure as a general approach for the engineering of RNase P ribozymes.RNA enzymes are being developed as promising gene-targeting reagents to specifically cleave RNA sequences of choice (1-3). For example, both hammerhead and hairpin ribozymes have been shown to cleave viral mRNA sequences and inhibit viral replication in cells infected with human viruses, while a ribozyme derived from a group I intron has been used to repair mutant mRNAs in cells (4 -9). Thus, ribozymes can be used as a tool in both basic and clinical research, such as in studies of tumorigenesis and antiviral gene therapy.RNase P is a ribonucleoprotein complex responsible for the 5Ј maturation of tRNAs (10, 11). It catalyzes a hydrolysis reaction to remove a 5Ј leader sequence from tRNA precursors (ptRNA) 1 and several other small RNAs . In Escherichia coli, RNase P consists of a catalytic RNA subunit (M1 RNA) and a protein subunit (C5 protein) (10, 11). In the presence of a high concentration of salt, such as 100 mM Mg 2ϩ , M1 RNA acts as a catalyst and cleaves ptRNAs in vitro in the absence of C5 protein (12). Extensive studies with both phylogenetic and biochemical analyses have established models for the secondary and threedimensional structures of RNase P catalytic RNAs (13-16). These models provide a framework to identify the putative active site and substrate binding site, and to study the mechanism of RNase P catalytic RNAs.Studies on substrate recognition by RNase P have revealed that a small model substrate can be cleaved efficiently by M1 ribozyme (Fig. 1A). This model substrate contains a structure equivalent to the acceptor stem, the T-stem, the 3Ј CCA sequence, and the 5Ј leader sequence of a ptRNA molecule. Accordingly, M1 catalytic RNA can cleave a mRNA sequence if the mRNA substrate forms a hybrid complex with its complementary sequence (external guide sequence) (Fig. 1A) (17). Moreover, a sequen...

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The fibroblast growth factor (FGF) pathway promotes tumor growth and angiogenesis in many solid tumors. Although there has long been interest in FGF pathway inhibitors, development has been complicated: An effective FGF inhibitor must block the activity of multiple mitogenic FGF ligands but must spare the metabolic hormone FGFs (FGF-19, FGF-21, and FGF-23) to avoid unacceptable toxicity. To achieve these design requirements, we engineered a soluble FGF receptor 1 Fc fusion protein, FP-1039. FP-1039 binds tightly to all of the mitogenic FGF ligands, inhibits FGF-stimulated cell proliferation in vitro, blocks FGF- and vascular endothelial growth factor (VEGF)-induced angiogenesis in vivo, and inhibits in vivo growth of a broad range of tumor types. FP-1039 antitumor response is positively correlated with RNA levels of FGF2, FGF18, FGFR1c, FGFR3c, and ETV4; models with genetic aberrations in the FGF pathway, including FGFR1-amplified lung cancer and FGFR2-mutated endometrial cancer, are particularly sensitive to FP-1039-mediated tumor inhibition. FP-1039 does not appreciably bind the hormonal FGFs, because these ligands require a cell surface co-receptor, klotho or β-klotho, for high-affinity binding and signaling. Serum calcium and phosphate levels, which are regulated by FGF-23, are not altered by administration of FP-1039. By selectively blocking nonhormonal FGFs, FP-1039 treatment confers antitumor efficacy without the toxicities associated with other FGF pathway inhibitors.

With increasing timeline pressures to get therapeutic and vaccine candidates into the clinic, resource intensive approaches such as the use of shake flasks and bench-top bioreactors may limit the design space for experimentation to yield highly productive processes. The need to conduct large numbers of experiments has resulted in the use of miniaturized high-throughput (HT) technology for process development. One such high-throughput system is the SimCell platform, a robotically driven, cell culture bioreactor system developed by BioProcessors Corp. This study describes the use of the SimCell micro-bioreactor technology for fed-batch cultivation of a GS-CHO transfectant expressing a model IgG4 monoclonal antibody. Cultivations were conducted in gas-permeable chambers based on a micro-fluidic design, with six micro-bioreactors (MBs) per micro-bioreactor array (MBA). Online, non-invasive measurement of total cell density, pH and dissolved oxygen (DO) was performed. One hundred fourteen parallel MBs (19 MBAs) were employed to examine process reproducibility and scalability at shake flask, 3- and 100-L bioreactor scales. The results of the study demonstrate that the SimCell platform operated under fed-batch conditions could support viable cell concentrations up to least 12 x 10(6) cells/mL. In addition, both intra-MB (MB to MB) as well as intra-MBA (MBA to MBA) culture performance was found to be highly reproducible. The intra-MB and -MBA variability was calculated for each measurement as the coefficient of variation defined as CV (%) = (standard deviation/mean) x 100. The % CV values for most intra-MB and intra-MBA measurements were generally under 10% and the intra-MBA values were slightly lower than those for intra-MB. Cell growth, process parameters, metabolic and protein titer profiles were also compared to those from shake flask, bench-top, and pilot scale bioreactor cultivations and found to be within +/-20% of the historical averages.