Monitoring antivascular therapy in head and neck cancer xenografts using contrast-enhanced MR and US imaging.

BACKGROUND: The overall goal of this study was to non-invasively monitor changes in blood flow of squamous cell carcinoma of the head and neck (SCCHN) xenografts using contrast-enhanced magnetic resonance (MR) and ultrasound (US) imaging. METHODS: Experimental studies were performed on mice bearing FaDu tumors and SCCHN xenografts derived from human surgical tissue. MR examinations were performed using gadofosveset trisodium at 4.7T. Change in T1-relaxation rate of tumors (ΔR1) and tumor enhancement parameters (amplitude, area under the curve-AUC) were measured at baseline and 24 h after treatment with a tumor-vascular disrupting agent (tumor-VDA), 5,6-dimethylxanthenone-4-acetic acid (DMXAA; ASA404) and correlated with tumor necrosis and treatment outcome. CE-US was performed using microbubbles (Vevo MicroMarker®) to assess the change in relative tumor blood volume following VDA treatment. RESULTS: A marked decrease (up to 68% of baseline) in T1-enhancement of FaDu tumors was observed 1 day after VDA therapy indicative of a reduction in blood flow. Early (24 h) vascular response of individual tumors to VDA therapy detected by MRI correlated with tumor necrosis and volume estimates at 10 days post treatment. VDA treatment also resulted in a significant reduction in AUC and amplitude of patient tumor-derived SCCHN xenografts. Consistent with MRI observations, CE-US revealed a significant reduction in tumor blood volume of patient tumor-derived SCCHN xenografts after VDA therapy. Treatment with VDA resulted in a significant tumor growth inhibition of patient tumor derived SCCHN xenografts. CONCLUSIONS: These findings demonstrate that both CE-MRI and CE-US allow monitoring of early changes in vascular function following VDA therapy. The results also demonstrate, for the first time, potent vascular disruptive and antitumor activity of DMXAA against patient tumor-derived head and neck carcinoma xenografts.

A comparative genomic analysis of ESTs from Ustilago maydis.

A large-scale comparative genomic analysis of unisequence sets obtained from an Ustilago maydis EST collection was performed against publicly available EST and genomic sequence datasets from 21 species. We annotated 70% of the collection based on similarity to known sequences and recognized protein signatures. Distinct grouping of the ESTs, defined by the presence or absence of similar sequences in the species examined, allowed the identification of U. maydis sequences present only (1) in fungal species, (2) in plants but not animals, (3) in animals but not plants, or (4) in all three eukaryotic lineages assessed. We also identified 215 U. maydis genes that are found in the ascomycete but not in the basidiomycete genome sequences searched. Candidate genes were identified for further functional characterization. These include 167 basidiomycete-specific sequences, 58 fungal pathogen-specific sequences (including 37 basidiomycete pathogen-specific sequences), and 18 plant pathogen-specific sequences, as well as two sequences present only in other plant pathogen and plant species.

Gene expression and EST analyses of Ustilago maydis germinating teliospores.

Ustilago maydis grows in its host Zea mays eliciting the formation of obvious tumors that are full of black teliospores. Teliospores are thick-walled, dormant, diploid cells that have evolved for dispersal and survival of the pathogen. Their germination leads to new rounds of infection and is temporally linked to meiosis. We are investigating gene expression during teliospore germination to gain insight into the control of this process. Here we identify genes expressed through creation of an expressed sequence tag (EST) library. We generated 2871 ESTs that are assembled into 1293 contiguous sequences. Based upon a blast search similarity cutoff of E < or =10(-5) 38% of all contigs were orphans while 62% showed similarity to sequences in the protein database. Analyses of blast searches were used to functionally classify genes. Northern hybridizations using specific cDNA clones reveal a relative level of expression consistent with the number of sequences per contig. Identified genes and expression information provide a base for genome annotation of U. maydis and further investigation of teliospore germination and pathogenesis.