Elucidating the transcriptional program of feline injection-site sarcoma using a cross-species mRNA-sequencing approach.

BACKGROUND: Feline injection-site sarcoma (FISS), an aggressive iatrogenic subcutaneous malignancy, is challenging to manage clinically and little is known about the molecular basis of its pathogenesis. Tumor transcriptome profiling has proved valuable for gaining insights into the molecular basis of cancers and for identifying new therapeutic targets. Here, we report the first study of the FISS transcriptome and the first cross-species comparison of the FISS transcriptome with those of anatomically similar soft-tissue sarcomas in dogs and humans. METHODS: Using high-throughput short-read paired-end sequencing, we comparatively profiled FISS tumors vs. normal tissue samples as well as cultured FISS-derived cell lines vs. skin-derived fibroblasts. We analyzed the mRNA-seq data to compare cancer/normal gene expression level, identify biological processes and molecular pathways that are associated with the pathogenesis of FISS, and identify multimegabase genomic regions of potential somatic copy number alteration (SCNA) in FISS. We additionally conducted cross-species analyses to compare the transcriptome of FISS to those of soft-tissue sarcomas in dogs and humans, at the level of cancer/normal gene expression ratios. RESULTS: We found: (1) substantial differential expression biases in feline orthologs of human oncogenes and tumor suppressor genes suggesting conserved functions in FISS; (2) a genomic region with recurrent SCNA in human sarcomas that is syntenic to a feline genomic region of probable SCNA in FISS; and (3) significant overlap of the pattern of transcriptional alterations in FISS with the patterns of transcriptional alterations in soft-tissue sarcomas in humans and in dogs. We demonstrated that a protein, BarH-like homeobox 1 (BARX1), has increased expression in FISS cells at the protein level. We identified 11 drugs and four target proteins as potential new therapies for FISS, and validated that one of them (GSK-1059615) inhibits growth of FISS-derived cells in vitro. CONCLUSIONS: (1) Window-based analysis of mRNA-seq data can uncover SCNAs. (2) The transcriptome of FISS-derived cells is highly consistent with that of FISS tumors. (3) FISS is highly similar to soft-tissue sarcomas in dogs and humans, at the level of gene expression. This work underscores the potential utility of comparative oncology in improving understanding and treatment of FISS.

Persistence of Gamma-H2AX Foci in Bronchial Cells Correlates with Susceptibility to Radiation Associated Lung Cancer in Mice.

The risk of developing radiation-induced lung cancer differs between different strains of mice, but the underlying cause of the strain differences is unknown. Strains of mice also differ in how quickly they repair radiation-induced DNA double-strand breaks (DSBs). We assayed mouse strains from the CcS/Dem recombinant congenic strain set for their efficacy in repairing DNA DSBs during protracted irradiation. We measured unrepaired γ-H2AX radiation-induced foci (RIF), which persisted after chronic 24-h gamma irradiation, as a surrogate marker for repair efficiency in bronchial epithelial cells for 17 of the CcS/Dem strains and the BALB/c founder strain. We observed a very strong correlation (R2 = 79.18%, P < 0.001) between the level of unrepaired RIF and radiogenic lung cancer incidence measured in the same strains. Interestingly, spontaneous levels of foci in nonirradiated mice also showed good correlation with lung cancer incidence when incidence data from male and female mice were combined. These results suggest that genetic differences in DNA repair capacity largely account for differing susceptibilities to radiation-induced lung cancer among CcS/Dem mouse strains, and that high levels of spontaneous DNA damage are also a relatively good marker of cancer predisposition. In a smaller pilot study, we found that the repair capacity measured in peripheral blood leucocytes also correlated well with radiogenic lung cancer susceptibility, raising the possibility that the assay could be used to detect radiogenic lung cancer susceptibility in humans.

Classical ligands bind tubulin of trypanosomes and inhibit their growth in vitro.

Tubulin ligands known to be toxic to certain organisms or cells were tested for their ability to inhibit proliferation of trypanosomes in culture. Tubulin was purified from Trypanosoma brucei brucei or rat brain by poly-L-lysine affinity chromatography and used in binding studies in order to compare the binding of [3H]mebendazole to trypanosome and mammalian tubulin. All the compounds tested in culture inhibited trypanosome proliferation in a concentration-dependent manner. The concentration required to inhibit trypanosome proliferation by 50 or 90% (IC50 or IC90) in 24 hr was determined for each compound. There were no significant differences (P > 0.05) among the benzimidazoles (BZs), but colchicine and vinblastine caused significantly greater inhibitions than the BZs (P < 0.02 and P < 0.005, respectively). Increasing the incubation time to 72 hr caused a 2- to 4-fold lowering of the IC50 and IC90 values for all the drugs. In the binding assays, there was higher total binding of [3H]mebendazole to trypanosome than rat brain tubulin. The results suggest that the inhibition of trypanosome growth was caused by the specific interaction of these ligands with trypanosome tubulin. Trypanosome tubulin is, therefore, a reasonable target against which novel drugs can be developed to control trypanosomiasis.