Identification of Potential Prognostic Biomarkers in Patients with Untreated, Advanced Pancreatic Cancer from a Phase III Trial (CALGB 80303)

Patients with advanced stage adenocarcinoma of the pancreas have a poor prognosis. The identification of prognostic and/or predictive biomarkers may help stratify patients so that therapy can be individualized

Upregulation of complement proteins in lung cancer cells mediates tumor progression

IntroductionIn vivo, cancer cells respond to signals from the tumor microenvironment resulting in changes in expression of proteins that promote tumor progression and suppress anti-tumor immunity. This study employed an orthotopic immunocompetent model of lung cancer to define pathways that are altered in cancer cells recovered from tumors compared to cells grown in culture.MethodsStudies used four murine cell lines implanted into the lungs of syngeneic mice. Cancer cells were recovered using FACS, and transcriptional changes compared to cells grown in culture were determined by RNA-seq.ResultsChanges in interferon response, antigen presentation and cytokine signaling were observed in all tumors. In addition, we observed induction of the complement pathway. We previously demonstrated that activation of complement is critical for tumor progression in this model. Complement can play both a pro-tumorigenic role through production of anaphylatoxins, and an anti-tumorigenic role by promoting complement-mediated cell killing of cancer cells. While complement proteins are produced by the liver, expression of complement proteins by cancer cells has been described. Silencing cancer cell-specific C3 inhibited tumor growth In vivo. We hypothesized that induction of complement regulatory proteins was critical for blocking the anti-tumor effects of complement activation. Silencing complement regulatory proteins also inhibited tumor growth, with different regulatory proteins acting in a cell-specific manner.DiscussionBased on these data we propose that localized induction of complement in cancer cells is a common feature of lung tumors that promotes tumor progression, with induction of complement regulatory proteins protecting cells from complement mediated-cell killing

Intracellular Expression of Peptide Fusions for Demonstration of Protein Essentiality in Bacteria

We describe a “protein knockout” technique that can be used to identify essential proteins in bacteria. This technique uses phage display to select peptides that bind specifically to purified target proteins. The peptides are expressed intracellularly and cause inhibition of growth when the protein is essential. In this study, peptides that each specifically bind to one of seven essential proteins were identified by phage display and then expressed as fusions to glutathione S-transferase in Escherichia coli. Expression of peptide fusions directed against E. coli DnaN, LpxA, RpoD, ProRS, SecA, GyrA, and Era each dramatically inhibited cell growth. Under the same conditions, a fusion with a randomized peptide sequence did not inhibit cell growth. In growth-inhibited cells, inhibition could be relieved by concurrent overexpression of the relevant target protein but not by coexpression of an irrelevant protein, indicating that growth inhibition was due to a specific interaction of the expressed peptide with its target. The protein knockout technique can be used to assess the essentiality of genes of unknown function emerging from the sequencing of microbial genomes. This technique can also be used to validate proteins as drug targets, and their corresponding peptides as screening tools, for discovery of new antimicrobial agents

A comparative analysis of EGFR-targeting antibodies for gold nanoparticle CT imaging of lung cancer.

Computed tomography (CT) is the standard imaging test used for the screening and assessment of suspected lung cancer, but distinguishing malignant from benign nodules by CT is an ongoing challenge. Consequently, a large number of avoidable invasive procedures are performed on patients with benign nodules in order to exclude malignancy. Improving cancer discrimination by non-invasive imaging could reduce the need for invasive diagnostics. In this work we focus on developing a gold nanoparticle contrast agent that targets the epidermal growth factor receptor (EGFR), which is expressed on the cell surface of most lung adenocarcinomas. Three different contrast agents were compared for their tumor targeting effectiveness: non-targeted nanoparticles, nanoparticles conjugated with full-sized anti-EGFR antibodies (cetuximab), and nanoparticles conjugated with a single-domain llama-derived anti-EGFR antibody, which is smaller than the cetuximab, but has a lower binding affinity. Nanoparticle targeting effectiveness was evaluated in vitro by EGFR-binding assays and in cell culture with A431 cells, which highly express EGFR. In vivo CT imaging performance was evaluated in both C57BL/6 mice and in nude mice with A431 subcutaneous tumors. The cetuximab nanoparticles had a significantly shorter blood residence time than either the non-targeted or the single-domain antibody nanoparticles. All of the nanoparticle contrast agents demonstrated tumor accumulation; however, the cetuximab-targeted group had significantly higher tumor gold accumulation than the other two groups, which were statistically indistinguishable from one another. In this study we found that the relative binding affinity of the targeting ligands had more of an effect on tumor accumulation than the circulation half life of the nanoparticles. This study provides useful insight into targeted nanoparticle design and demonstrates that nanoparticle contrast agents can be used to detect tumor receptor overexpression. Combining receptor status data with traditional imaging characteristics has the potential for better differentiation of malignant lung tumors from benign lesions

Enhanced CDC of B cell chronic lymphocytic leukemia cells mediated by rituximab combined with a novel anti-complement factor H antibody

<div><p>Rituximab therapy for B cell chronic lymphocytic leukemia (B-CLL) has met with mixed success. Among several factors to which resistance can be attributed is failure to activate complement dependent cytotoxicity (CDC) due to protective complement regulatory proteins, including the soluble regulator complement factor H (CFH). We hypothesized that rituximab killing of non-responsive B-CLL cells could be augmented by a novel human monoclonal antibody against CFH. The B cells from 11 patients with B-CLL were tested <i>ex vivo</i> in CDC assays with combinations of CFH monoclonal antibody, rituximab, and a negative control antibody. CDC of rituximab non-responsive malignant B cells from CLL patients could in some cases be augmented by the CFH monoclonal antibody. Antibody-mediated cytotoxicity of cells was dependent upon functional complement. In one case where B-CLL cells were refractory to CDC by the combination of rituximab plus CFH monoclonal antibody, additionally neutralizing the membrane complement regulatory protein CD59 allowed CDC to occur. Inhibiting CDC regulatory proteins such as CFH holds promise for overcoming resistance to rituximab therapy in B-CLL.</p></div

The effect of anti-CD59 antibody on CDC of RTX/CFH MAb nonresponder B-CLL cells with high mean CD59 expression levels (Patient #6).

<p>CDC reactions were carried out with NHS as a complement source. For each condition, the mean percent CDC was divided by the mean percent CDC of the αCon antibody to obtain "fold cytotoxicity". The CDC assay for the α-CFH + RTX condition was performed on a different day from the other conditions.</p