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T cells can be engineered to target tumor cells by transduction of tumor-specific chimeric receptors, consisting of an extracellular antigen-binding domain and an intracellular signaling domain. However, the peripheral blood of cancer patients frequently contains an increased number of T regulatory cells, which appear to inhibit immune reactivity. We have investigated the effects of T regulatory cells on chimeric T cells specific for the B-cell antigen CD19, as B-cell malignancies are attractive targets for chimeric T-cell therapy. When a CD19 single-chain Fv antibody was coupled to the CD3 zeta (ζ) chain, there was sharply reduced activity on exposure to T regulatory cells, measured by CD19+ target-induced proliferation and cytotoxicity. By contrast, expression in T cells of a chimeric receptor consisting of the intracellular portion of the CD28 molecule fused to the ζ-chain and CD19 single-chain Fv not only produced a higher proliferative response and an increased nuclear factor κB activation but also sustained these activities in the presence of T regulatory cells. These effects are seen whether the chimeric T cells are derived from normal donors or from patients with B-cell chronic lymphocytic leukemia, indicating the potential for clinical application in B cell malignancies.Leukemia (2006) 20, 1819–1828. doi:10.1038/sj.leu.2404366; published online 17 August 2006 [ABSTRACT FROM AUTHOR]

Oncolytic viruses are emerging as anticancer agents, and they have also shown great promise for use against neuroendocrine tumors. Many viruses have a natural tropism for replication in tumor cells. Others can be genetically engineered to selectively kill tumor cells. Viruses have some advantages as therapeutic agents over current cytotoxic drugs and small molecules. They replicate in tumor cells and thereby increase in number over time leading to increased dosage. They are immunogenic and can alter the immunosuppressive tumor microenvironment and activate immune effector cells. They have also been shown to be able to kill drug-resistant cancer stem cells. This article reviews the recent literature on oncolytic viruses used so far for neuroendocrine tumors and indicates important issues to focus on in the future. [ABSTRACT FROM AUTHOR]

Cytomegalovirus (CMV) disease remains a severe complication in patients who have undergone transplantation. Viremia can be prevented and treated by the adoptive transfer of donor-derived CMV-directed T cells. To ensure long-term protection against CMV disease, it is important to transfer CMV antigen-specific T cells that represent both the CD8+ and the CD4+ subsets. In the present study, we used as stimulators dendritic cells (DCs) that were electroporated with in vitro-transcribed 5'-capped polyadenylated messenger RNA (mRNA) that encoded the CMV pp65 protein (i.e., pp65 mRNA). These DCs could efficiently activate CMV-directed CD8+ T cells, as assayed by tetramer staining, interferon- gamma production, and cytolytic activity. We also used DCs that were pulsed with a recombinant pp65 protein to activate CMV-directed CD4+ T cells. When DCs were comodified with pp65 mRNA and pp65 protein, large numbers of CMV-directed CD8+ and CD4+ T cells were generated simultaneously. The approach outlined in the present study can be adapted for a clinical protocol that circumvents potential virus-related biohazards and is available to all patients independently of their human leukocyte antigen haplotype. Copyright © 2005 Infectious Diseases Society of America [ABSTRACT FROM AUTHOR]

We have previously described the oncolytic adenovirus, Ad(CgA-E1A-miR122), herein denoted Ad5(CgA-E1A-miR122) that selectively replicates in and kills neuroendocrine cells, including freshly isolated midgut carcinoid cells from liver metastases. Ad5(CgA-E1A-miR122) is based on human adenovirus serotype 5 (Ad5) and infects target cells by binding to the coxsackie-adenovirus receptor (CAR) and integrins on the cell surface. Some neuroendocrine tumor (NET) and neuroblastoma cells express low levels of CAR and are therefore poorly transduced by Ad5. However, they often express high levels of somatostatin receptors (SSTRs). Therefore, we introduced cyclic peptides, which contain four amino acids (FWKT) and mimic the binding site for SSTRs in the virus fiber knob. We show that FWKT-modified Ad5 binds to SSTR2 on NET cells and transduces midgut carcinoid cells from liver metastases about 3-4 times better than non-modified Ad5. Moreover, FWKT-modified Ad5 overcomes neutralization in an ex vivo human blood loop model to greater extent than Ad5, indicating that fiber knob modification may prolong the systemic circulation time. We conclude that modification of adenovirus with the FWKT motif may be beneficial for NET therapy. [ABSTRACT FROM AUTHOR]

Introduction: Small intestinal neuroendocrine tumors (SI-NETs) arise from enterochromaffin cells, which belong to the endocrine system. MicroRNAs (miRs) are post-transcriptional regulators. They control multiple biological processes often functioning either as tumor suppressor genes or oncogenes. Aim(s): To identify an exclusive SI-NETs miR profile, which may have a critical role in progression of these rare tumors. Materials and methods: Fifteen SI-NET frozen specimens (five primary tumors, five mesentery metastases and five liver metastases) and five human NET cell lines were included in the study. Total RNA was used for genome-wide Affymetrix miR arrays. QRT-PCR and northern blot verified differentially expressed miRs. Furthermore, microdissected SI-NET cells were used to identify miR expression. In addition, TargetScan was used to predicate potential miR target genes. Results: Affymetrix miR arrays detected nine miRs, which are significantly altered between primary tumors and metastases. Five (miR-96, -182, -183, -196a and -200a) are upregulated, whereas four (miR-31, -129-5p, -133a and -215) are down-regulated during tumor progression. The selected 9 miRs are specifically expressed on microdissected SI-NET cells. Conclusion: The genome-wide SI-NET miR profile provides potential pivotal miRs. They may be critical either in the progression mechanisms or developed as novel therapeutic targets. [ABSTRACT FROM AUTHOR]

Introduction: Octreotide is a somatostatin analogue, which improves the management of neuroendocrine tumor (NET) patients. Octreotide acts through somatostatin receptors (SSTRs). However, the molecular mechanisms leading to successful therapy or curative effects are largely unknown, particularly when SSTRs levels are low or absent. Aim(s): To provide novel insights into regulative octreotide pathways on human NET cells using CNDT2.5 as a novel in vitro model. Materials and methods: CNDT2.5 cells were treated from one day up to 16 months with Octreotide and then were profiled using Affymetrix microarray analysis. QRTPCR, western blot and immunohistochemistry analyses validated CNDT2.5 cells in silico data. In addition, small-intestine-NET tissue blocks at different stages of disease and laser-microdissected tumor cells analyses confirmed the findings. Results: One of the major novel findings is that Octreotide upregulates six genes, ANXA1, ARHGAP18, EMP1, GDF15, TGFBR2 and TNFSF15, which have not previously correlated to Octreotide effects. Furthermore, the genes were transcriptional and translational regulated in tumor tissues. Conclusion: Octreotide may use a potential novel framework to convey its action on neuroendocrine cells and exert its regulative effects. Indeed, the six addressed genes may regulate cell growth and differentiation in normal and tumor neuroendocrine cells. [ABSTRACT FROM AUTHOR]

Introduction: Small intestine neuroendocrine tumors (SI-NETs) get late diagnosis. We discovered the olfactory receptor 51El (OR51E1) as a potential target to develop as a novel biomarker. Aim(s): To develop OR51E1 as a SI-NET novel tissue biomarker for diagnostics and prognostics. Materials and methods: OR51El coding sequence was cloned from SI-NET patient specimens and NET cell lines. OR51E1 expression was analyzed by quantitative-real-time-PCR (QRT-PCR) on human normal and NET cell lines; normal liver tissue and normal hepatic cells; microdissected SI-NET cells and stroma cells. OR51El protein expression was analyzed by immunohistochemistry (IHC) on SI-NET slides and tissue microarray analysis (TMA). Furthermore, a new polyclonal antibody was developed. Results: OR51E1 coding sequence is identical in NETs and normal tissue. NET cell lines express OR51E1 at different levels. QRT-PCR analysis shows higher OR51E1 expression in microdissected SI-NET cells than do stroma cells. IHC and TMA show OR51E1 expression in SI-NETs and other cancer tissues. We detected OR51E1 protein in normal liver tissue. However, QRTPCR did not detect OR51E 1 expression in total RNA from different normal hepatic cells and normal liver tissue. Conclusion: OR51E1 is a potential biomarker for the diagnosis and progression of SI-NETs. However, further analysis and production of specific antibodies are ongoing to develop OR51EI as a new SI-NET biomarker. [ABSTRACT FROM AUTHOR]