vasoactive-intestinal-peptide and Leukemia

Ghrelin is a 28 amino acid peptide hormone that is mainly produced by the stomach, but also by several tissues and tumors. Ghrelin is octanoylated on the Ser(3), but is also detected as a des-acylated form. Only the acylated ghrelin activates the GH secretagogue receptor (GHS-R) type 1a to stimulate GH release, and regulate food intake and energy metabolism. For the first time, we report that ghrelin and des-acyl ghrelin are present in human promyelocytic HL-60, monocytic THP-1 and lymphoblastic SupT1 cell lines. The human leukemic cell lines did not express the functional GHS-R 1a, whereas they expressed GHS-R 1b, a truncated variant of the receptor. Leukemic cell proliferation was not modified by the addition of octanoylated or des-acyl ghrelins. However, THP-1 and HL-60 cell proliferations were inhibited by SB801, an antibody directed against the N-terminal octanoylated portion of ghrelin, suggesting that octanoylated ghrelin stimulates cell proliferation via an autocrine pathway involving an as yet unidentified ghrelin receptor. Both octanoylated and des-acyl ghrelins did not alter the basal adenylate cyclase activity. Treatments of THP-1 and SupT1 cells by both octanoylated and des-acyl ghrelins did not modify the adenylate cyclase activity in response to vasoactive intestinal peptide, suggesting that ghrelin is unlikely to modulate the anti-inflammatory and differentiating properties of vasoactive intestinal peptide.

Topics: Adenylyl Cyclases; Autocrine Communication; Carboxylesterase; Cell Line, Tumor; Cell Proliferation; Ghrelin; HL-60 Cells; Humans; Leukemia; Leukemia, Lymphoid; Leukemia, Monocytic, Acute; Leukemia, Promyelocytic, Acute; Peptide Hormones; Receptors, G-Protein-Coupled; Receptors, Ghrelin; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Vasoactive Intestinal Peptide

Acute graft-versus-host disease (GVHD) is a major cause of morbidity and mortality in patients undergoing allogeneic bone marrow transplantation (BMT) for the treatment of leukemia and other immunogenetic disorders. The use of tolerogenic dendritic cells (DCs) with potent immunoregulatory properties by inducing the generation/activation of regulatory T cells (Tr) for the treatment of acute GVHD following allogeneic BMT has been recently established. Here we report the use of the known immunosuppressive neuropeptide, vasoactive intestinal polypeptide (VIP), as a new approach to inducing tolerogenic DCs with the capacity to prevent acute GVHD. DCs differentiated with VIP impair allogeneic haplotype-specific responses of donor CD4+ T cells in transplanted mice by inducing the generation of Tr in the graft. Importantly, VIP-induced tolerogenic DCs did not abrogate the graft versus leukemia response, probably because they do not abrogate cytotoxicity of transplanted T cells against the leukemic cells. Therefore, the inclusion of VIP-induced tolerogenic DC in future therapeutic regimens may facilitate the successful transplantation from mismatched donors, reducing the deleterious consequences of acute GVHD, extending the applicability of BMT.

Topics: Acute Disease; Animals; Bone Marrow Transplantation; Cell Differentiation; Dendritic Cells; Graft vs Host Disease; Leukemia; Mice; Survival Rate; Vasoactive Intestinal Peptide

The neuropeptides Vasoactive-intestinal peptide (VIP) and Pituitary adenylate-cyclase activating protein (PACAP) increased cAMP levels in three out of five human myeloid leukemic cell lines tested while an increased in calcium intracytoplasmic levels was seen only in one cell line (HEL). This increase was phospholipase C, Pertussis toxin dependent and associated with an increase in c-fos and c-jun protein expression together with the formation of functional AP-1 transcriptional factor complex. Cell exposure to VIP or PACAP resulted in a decrease in HEL cell proliferation associated with a down-regulation of the erythroid marker, Glycophorin A. Both peptides were found to increase intra-cytoplasmic calcium levels in blasts isolated from patients with myeloid leukemia. Thus VIP and PACAP are involved in the physiology and pathophysiology of human myeloid cells.

Topics: Adenosine Triphosphate; Bromodeoxyuridine; Calcium; Cell Line, Tumor; Cyclic AMP; Cytarabine; Cytosol; DNA Fragmentation; Dose-Response Relationship, Drug; Drug Interactions; Electrophoretic Mobility Shift Assay; Enzyme Inhibitors; Enzyme-Linked Immunosorbent Assay; Estrenes; Flow Cytometry; Glycophorins; Humans; Immunosuppressive Agents; Inositol Phosphates; Intercellular Adhesion Molecule-1; Leukemia; Myeloid Cells; Neuropeptides; Pituitary Adenylate Cyclase-Activating Polypeptide; Protein Binding; Proto-Oncogene Proteins; Pyrrolidinones; Receptors, Vasoactive Intestinal Peptide; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Signal Transduction; Tetradecanoylphorbol Acetate; Thrombin; Time Factors; Transcription Factor AP-1; Vasoactive Intestinal Peptide

The activation of the cAMP signaling pathway by vasoactive intestinal peptide (VIP), pituitary adenylate cyclase-activating peptide (PACAP) and related peptides was studied (i) in normal peripheral human monocytes and THP-1 leukemic human monocytes, (ii) in their derived macrophage counterparts respectively obtained after spontaneous differentiation or retinoic acid (RA) treatment, and (iii) in human bronchoalveolar macrophages. In THP-1 monocytes, PACAP increased basal adenylate cyclase activity 5.3-fold, with an affinity 50-times greater than that of VIP or helodermin (Ka = 3.2 x 10(-11) M VIP), whereas in normal peripheral monocytes, PACAP and VIP exhibited similar affinities and only increased cAMP generation 2-fold (EC50 = 10(-9) M). Spontaneous and RA-induced differentiation into normal and leukemic macrophages induced a progressive loss of cAMP production and regulation of superoxide anion production by VIP and related peptides. The neoplastic transformation in THP-1 monocytes and the deficiencies in the cAMP cascade observed during the terminal differentiation of normal and leukemic human macrophages may relate to a differential genetic expression of the VIP/PACAP receptor subtypes, and alterations in the functional activity of the stimulatory and inhibitory Gs/Gi subunits of adenylate cyclase.

Topics: Adenylyl Cyclases; Cell Differentiation; Cell Transformation, Neoplastic; Colforsin; Cyclic AMP; Enzyme Activation; Humans; Hydrogen Peroxide; Isoproterenol; Leukemia; Macrophages; Monocytes; Neuropeptides; Pituitary Adenylate Cyclase-Activating Polypeptide; Pulmonary Alveoli; Signal Transduction; Superoxides; Tretinoin; Tumor Cells, Cultured; Vasoactive Intestinal Peptide

Vasoactive intestinal peptide (VIP) is a neuroendocrine mediator found in the central and peripheral nervous system. Distinct subsets of neural, respiratory, gastrointestinal, and immune cells bear specific high-affinity receptors for VIP, which are associated with a guanine nucleotide-binding (G) protein capable of activating adenylate cyclase. A cDNA clone (GPRN1) encoding the human VIP receptor was identified in libraries prepared from the Nalm 6 line of leukemic pre-B lymphoblasts and the HT-29 line of colon carcinoma cells. The deduced 362-amino acid polypeptide sequence encoded by GPRN1 shares a seven-transmembrane-segment hydropathicity profile with other G protein-coupled receptors. Northern blot analyses identified a 2.7-kilobase transcript of the VIP receptor in Nalm 6 and HT-29 cells as well as in tissues from rat brain, colon, heart, lung, kidney, spleen, and small intestine. COS-6 cells transfected with GPRN1 bound 125I-labeled VIP specifically with a dissociation constant (Kd) of 2.5 nM. VIP--and less effectively secretin, peptide histidine isoleucine (PHI), and glucagon competitively displaced bound 125I-VIP from transfected COS-6 cells, with potencies in the order VIP greater than secretin = PHI much greater than glucagon. VIP stimulated adenylate cyclase activity in stably transfected Chinese hamster ovary K1 cells, inducing a 3-fold increase in the intracellular level of cAMP. When the antisense orientation of the VIP receptor clone was introduced into HT-29 cells, there was a 50% suppression of the specific binding of 125I-VIP and of the VIP-induced increase in cAMP level, relative to untransfected cells. The VIP receptor cloned exhibits less than or equal to 24% homology with other receptors in the same superfamily and thus represents a subset of G protein-coupled receptors for peptide ligands.

Topics: Amino Acid Sequence; Animals; Blotting, Northern; Cell Line; Cloning, Molecular; Colonic Neoplasms; Gene Library; Humans; Kinetics; Leukemia; Molecular Sequence Data; Poly A; Protein Conformation; Rats; Receptors, Gastrointestinal Hormone; Receptors, Vasoactive Intestinal Peptide; Recombinant Proteins; RNA, Messenger; Sequence Homology, Nucleic Acid; Transcription, Genetic; Transfection; Vasoactive Intestinal Peptide

Peptide mediators of sensory nerves that are released in tissues by noxious chemical and physical insults and by diverse biologic challenges rapidly elicit local and systemic responses similar to those of immediate hypersensitivity. The sensory neuropeptides have direct effects on the functions of smooth muscles, blood vessels, leukocytes, and epithelial glands and indirect effects through the actions of mediators released from mast cells stimulated by the peptides. Sensory neuropeptides exhibit cellular specificity, as exemplified by the greater potency of substance P in activating mucosal mast cells than connective tissue mast cells. The capacity of somatostatin to inhibit release of mediators from basophils challenged by IgE-dependent mechanisms, but not by basic peptides or ionophores, illustrates the biochemical specificity of the neuropeptides. The selective release of distinct sensory neuropeptides from different subsets of nerve endings, the specificity of neuropeptide recognition by mast cells, basophils, and other target cells, and the diversity of direct and indirect activities of the neuropeptides suggest that sensory nerves may initiate and modulate immediate hypersensitivity by unique mechanisms.

Topics: Basophils; Endorphins; Humans; Hypersensitivity, Immediate; Leukemia; Mast Cells; Nerve Tissue Proteins; Neurotensin; Neurotransmitter Agents; Somatostatin; Substance P; Vasoactive Intestinal Peptide

Topics: Gastrointestinal Hormones; Glucagon; Humans; Leukemia; Monocytes; Neutrophils; Radioimmunoassay; Vasoactive Intestinal Peptide