Zebrafish Models of Rare Hereditary Pediatric Diseases.

Recent advances in sequencing technologies have made it significantly easier to find the genetic roots of rare hereditary pediatric diseases. These novel methods are not panaceas, however, and they often give ambiguous results, highlighting multiple possible causative mutations in affected patients. Furthermore, even when the mapping results are unambiguous, the affected gene might be of unknown function. In these cases, understanding how a particular genotype can result in a phenotype also needs carefully designed experimental work. Model organism genetics can offer a straightforward experimental setup for hypothesis testing. Containing orthologs for over 80% of the genes involved in human diseases, zebrafish (Danio rerio) has emerged as one of the top disease models over the past decade. A plethora of genetic tools makes it easy to create mutations in almost any gene of the zebrafish genome and these mutant strains can be used in high-throughput preclinical screens for active molecules. As this small vertebrate species offers several other advantages as well, its popularity in biomedical research is bound to increase, with "aquarium to bedside" drug development pipelines taking a more prevalent role in the near future.

Erythropoietin receptor expression is a potential prognostic factor in human lung adenocarcinoma.

Recombinant human erythropoietins (rHuEPOs) are used to treat cancer-related anemia. Recent preclinical studies and clinical trials, however, have raised concerns about the potential tumor-promoting effects of these drugs. Because the clinical significance of erythropoietin receptor (EPOR) signaling in human non-small cell lung cancer (NSCLC) also remains controversial, our aim was to study whether EPO treatment modifies tumor growth and if EPOR expression has an impact on the clinical behavior of this malignancy. A total of 43 patients with stage III-IV adenocarcinoma (ADC) and complete clinicopathological data were included. EPOR expression in human ADC samples and cell lines was measured by quantitative real-time polymerase chain reaction. Effects of exogenous rHuEPOα were studied on human lung ADC cell lines in vitro. In vivo growth of human ADC xenografts treated with rHuEPOα with or without chemotherapy was also assessed. In vivo tumor and endothelial cell (EC) proliferation was determined by 5-bromo-2'-deoxy-uridine (BrdU) incorporation and immunofluorescent labeling. Although EPOR mRNA was expressed in all of the three investigated ADC cell lines, rHuEPOα treatment (either alone or in combination with gemcitabine) did not alter ADC cell proliferation in vitro. However, rHuEPOα significantly decreased tumor cell proliferation and growth of human H1975 lung ADC xenografts. At the same time, rHuEPOα treatment of H1975 tumors resulted in accelerated tumor endothelial cell proliferation. Moreover, in patients with advanced stage lung ADC, high intratumoral EPOR mRNA levels were associated with significantly increased overall survival. This study reveals high EPOR level as a potential novel positive prognostic marker in human lung ADC.

Inhibition of c-Met with the specific small molecule tyrosine kinase inhibitor SU11274 decreases growth and metastasis formation of experimental human melanoma.

The hepatocyte growth factor/scatter factor (HGF/SF) tyrosine kinase (TK) receptor c-Met plays a crucial role in the development of the invasive phenotype of tumors and thus represents an attractive candidate for targeted therapies in a variety of malignancies, including human malignant melanoma (MM). In contrast to what has been shown previously, we were not able to detect any genetic alterations, either in the juxtamembrane- or in the TK-domain of c-Met, in the studied MM cell lines. Nevertheless, c-Met was constitutively active in these cell lines without exogenous HGF/SF stimulation. The active receptor was localized to the adhesion sites of the cells. Addition of the c-Met TK inhibitor SU11274 specifically decreased the phosphotyrosine signal at the focal adhesions sites, which was accompanied by a decrease in cell proliferation as well as an increase in apoptotic cells. In addition, non-apoptotic concentrations of SU11274 significantly reduced the in vitro migratory capacity of MM cells in the modified Boyden-chamber assay. Administration of SU11274 significantly decreased primary tumor growth as well as the capacity for liver colony formation of MM cells in SCID mice. Our study provides the first evidence for an in vivo antitumor activity of SU11274 in a human melanoma xenograft model, and suggests c-Met as a valid target for the therapy of MM. Consequently, SU11274 treatment might represent a useful strategy for controlling melanoma progression and metastasis in patients with MM.