Stem cell-like brain tumor initiating cells (BTICs) cause recurrence of glioblastomas, with BTIC ‘stemness’ affected by epigenetic mechanisms. The ING family of epigenetic regulators (ING1-5) function by targeting histone acetyltransferase (HAT) or histone deacetylase complexes to the H3K4me3 mark to alter histone acetylation and subsequently, gene expression. Here we find that ectopic expression of ING5, the targeting subunit of HBO1, MOZ and MORF HAT complexes increases expression of the Oct4, Olig2 and Nestin stem cell markers, promotes self-renewal, prevents lineage differentiation and increases stem cell pools in BTIC populations. This activity requires the plant homeodomain region of ING5 that interacts specifically with the H3K4me3 mark. ING5 also enhances PI3K/AKT and MEK/ERK activity to sustain self-renewal of BTICs over serial passage of stem cell-like spheres. ING5 exerts these effects by activating transcription of calcium channel and follicle stimulating hormone pathway genes. In silico analyses of The Cancer Genome Atlas data suggest that ING5 is a positive regulator of BTIC stemness, whose expression negatively correlates with patient prognosis, especially in the Proneural and Classical subtypes, and in tumors with low SOX2 expression. These data suggest that altering histone acetylation status and signaling pathways induced by ING5 may provide useful clinical strategies to target tumor resistance and recurrence in glioblastoma.

Intramural haematoma of the oesophagus is an uncommon and under-recognized condition. It may mimic other causes of chest pain, haematemesis, or dysphagia, and hence pose a diagnostic challenge. We report a case of an unusual presentation of intramural haematoma of the oesophagus occurring as a presumed complication of endotracheal intubation. It was disguised as acute onset post-operative chest pain, and resolved with conservative management. Awareness of this uncommon complication is important to allow rapid and timely diagnosis and management. We review the literature, causes and imaging features of this condition.

#6003 Multifunctional nanoparticles with the ability to target tumors, provide molecular imaging and to deliver therapeutic agents hold great promise for improving the survival of cancer patients. We have developed multifunctional nanoparticles targeted to cellular receptors that are highly expressed in breast cancer and tumor stromal cells. Fluorescent quantum dot (QD) or magnetic iron oxide (IO) nanoparticles are conjugated to either the amino-terminal fragment (ATF) of urokinase plasminogen activator (uPA) or to a single chain antibody against the epidermal growth factor receptor (ScFvEGFR), resulting in uPAR or EGFR targeted nanoparticles. Since the binding of ATF peptides or ScFvEGFR to their receptors results in blocking receptor function and internalization of the receptor-ligand complex, these targeted imaging probes can also inhibit tumor growth and deliver drugs. Using near infrared fluorescence (NIR) dye-labeled targeting peptides, we demonstrate specificity of these targeting ligands in an orthotopic human breast cancer model in nude mice. We found that tail vein injection of a mixture of Cy5.5 dye-ATF and IRDye 800-ScFvEGFR peptides leads to the selective accumulation of both probes in human breast cancer xenografts and NIR optical imaging of the tumors in the mammary fat pad of nude mice (Fig. A).
 
 We show that uPAR- and EGFR-targeted nanoprobes display different patterns of intratumoral distribution with EGFR probes in the central area and uPAR probes in the peripheral and central regions of the tumor, which may be the results of expressing uPAR in the invasive edge of tumor cells and tumor stromal cells and EGFR only in tumor cells. In vivo optical imaging using ATF-nanoparticles is also demonstrated in human breast cancer xenograft (Fig. B) and in mouse mammary tumor lung metastatic models. Furthermore, magnetic Cy5.5-ATF IO nanoparticles are multimodality imaging probes for both optical and MR tumor imaging. Since magnetic IO nanoparticles are biodegradable and relatively safe for human use, we have developed a therapeutic imaging nanoparticle by encapsulating doxorubicin into the polymer coating of the nanoparticles and have shown selective delivery of the drug and cytotoxic effect in breast cancer cells in vitro. Results of our study show that multifunctional and multiplexed nanoparticles have great potential for the development of novel tumor imaging and therapeutic approaches. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 6003.

Mass spectrometry-based metaproteomics technologies enable the direct observation of proteins within complex multi-organism environments. A major hurdle in mapping metaproteomic fragmentation spectra to their corresponding peptides is the need for large peptide databases encompassing all anticipated species contained within a biological sample. As we cannot predict the taxonomic composition of microbiomes a priori, we developed the ComPIL database which contains a comprehensive collection of 4.8 billion unique peptides from public sequencing repositories to enable our proteomics analyses. We analyzed fecal samples from ulcerative colitis (UC) patients using a tandem mass spectrometry (LC-MS/MS) workflow coupled to ComPIL in search of aberrant UC-associated proteins. We found 176 host and microbial protein groups differentially enriched between the healthy (control) or UC volunteer groups. Notably, gene ontology (GO) enrichment analysis revealed that serine-type endopeptidases are overrepresented in UC compared to healthy volunteers. Additionally, we demonstrate the feasibility of serine hydrolase chemical enrichment from fecal samples using a biotinylated fluorophosphate (FP) probe. Our findings illustrate that probe-susceptible hydrolases from hosts and microbes are likely active in the distal gut. Finally, we applied de novo peptide sequencing methods to our metaproteomics data to estimate the size of the “dark peptidome,” the complement of peptides unidentified using ComPIL. We posit that our metaproteomics methods are generally applicable to future microbiota analyses and that our list of FP probe-enriched hydrolases may represent an important functionality to understanding the etiology of UC.

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