G-CSF receptor-binding cyclic peptides designed with artificial amino-acid linkers

G-CSF modulates innate and adaptive immunity via the ligand-receptor pathway of binding GCSFR in flounder (Paralichthys olivaceus)

Granulocyte colony stimulating factor (G-CSF) has been shown in mammalia to activate a series of signal transduction systems and exert various biological effects, such as controlling the differentiation, proliferation, and survival of granulocytes, promoting the movement of hematopoietic stem cells from the bone marrow to the bloodstream, and triggering the development of T cells, dendritic cells, and immune tolerance in transplants. In this study, the mRNA of flounder G-CSF (PoG-CSF) and its receptor (PoGCSFR) were detected and widely expressed in all examined tissues with the highest expression in peritoneal cells. G-CSF+ and GCSFR+ cells were observed to be abundantly distributed in the leukocytes from the peritoneal cavity, followed by head kidney. PoG-CSF was detected in IgM+, CD4+, MHCII+ and CD83+ cells which indicated that flounder lymphocytes, dendritic cells and other MHCII positive cells may produce G-CSF protein. PoGCSFR was expressed in the MPO+ cells, suggesting that PoGCSFR is mainly expressed in flounder granulocytes. In addition, rPoG-CSF demonstrated a capacity to enhance the phagocytosis of peritoneal cells and HK leukocytes in vitro. In vivo, the percentage of IgM+, CD4+, MHCII+, CD83+ and GCSFR+ cells in the peritoneal cavity increased after rPoG-CSF i.p. stimulation. It seemed that rPoG-CSF promoted the migration of innate cells from the head kidney into the peritoneal cavity. Meanwhile, administration of rPoG-CSF increased the expression levels of the inflammatory cytokines. Finally, drawing of the interfaces of G-CSF and GCSFR showed the principal hydrogen-bonding linkages. This study suggests that G-CSF as a pleiotropic growth factor binding to GCSFR may be involved in the regulation of innate and adaptive responses.

A review of granulocyte colony-stimulating factor receptor signaling and regulation with implications for cancer

Granulocyte colony-stimulating factor receptor (GCSFR) is a critical regulator of granulopoiesis. Studies have shown significant upregulation of GCSFR in a variety of cancers and cell types and have recognized GCSFR as a cytokine receptor capable of influencing both myeloid and non-myeloid immune cells, supporting pro-tumoral actions. This systematic review aims to summarize the available literature examining the mechanisms that control GCSFR signaling, regulation, and surface expression with emphasis on how these mechanisms may be dysregulated in cancer. Experiments with different cancer cell lines from breast cancer, bladder cancer, glioma, and neuroblastoma are used to review the biological function and underlying mechanisms of increased GCSFR expression with emphasis on actions related to tumor proliferation, migration, and metastasis, primarily acting through the JAK/STAT pathway. Evidence is also presented that demonstrates a differential physiological response to aberrant GCSFR signal transduction in different organs. The lifecycle of the receptor is also reviewed to support future work defining how this signaling axis becomes dysregulated in malignancies.

Analysis of the relationship between end-to-end distance and activity of single-chain antibody against colorectal carcinoma

We investigated the relationship of End-to-end distance between VH and VL with different peptide linkers and the activity of single-chain antibodies by computer-aided simulation. First, we developed (G4S)n (where n = 1-9) as the linker to connect VH and VL, and estimated the 3D structure of single-chain Fv antibody (scFv) by homologous modeling. After molecular models were evaluated and optimized, the coordinate system of every protein was built and unified into one coordinate system, and End-to-end distances calculated using 3D space coordinates. After expression and purification of scFv-n with (G4S)n as n = 1, 3, 5, 7 or 9, the immunoreactivity of purified ND-1 scFv-n was determined by ELISA. A multi-factorial relationship model was employed to analyze the structural factors affecting scFv: rn=ABn-ABO2+CDn-CDO2+BCn-BCst2. The relationship between immunoreactivity and r-values revealed that fusion protein structure approached the desired state when the r-value = 3. The immunoreactivity declined as the r-value increased, but when the r-value exceeded a certain threshold, it stabilized. We used a linear relationship to analyze structural factors affecting scFv immunoreactivity.

Bioinformatics-led design of single-chain antibody molecules targeting DNA sequences for retinoblastoma

AIM

To analyze the relationship between the structure and function of single-chain Fv antibody (scFv) with bioinformatics methods, so as to provide theoretical basis for retinoblastoma targeted therapy.

METHODS

Single-chain antibodies are reconstructed for cancer-targeted therapy to provide good penetration into tumor tissue and to improve their pharmacokinetics in vivo, offering a clinically valuable application. The relationship needs to be analyzed that there may be some variations between the structure and function of the fusion proteins, and the relationship between the structure and function of protein molecules was obtained through analyzing relevant literature at home and abroad as well as modeling analysis.

RESULTS

Through our analysis of the interaction region between the antibody and the antigen, and of the binding sites for molecular conformation, it is clear that existing antibodies need to be modified at the DNA sequence level, enhancing the biological activity of the antibodies. Based on the view that bio-molecular computer models are closely integrated with biological experiments, a bio-molecular structure-activity relationship model can be established in terms of molecular conformation, physical and chemical properties and the biological activity of single-chain antibodies. Two enlightenments are obtained from our analysis. On the one hand, the structure-activity relationship is clear for new immune molecules at the gene expression level. On the other hand, a single-chain antibody molecule can be designed and optimized for the cancer-oriented treatment.

CONCLUSION

In this article, we provide the theoretical and experimental basis for the development of single-chain antibodies appropriate for retinoblastoma therapy.

Neutrophil biology and the next generation of myeloid growth factors

Neutrophils are the body's critical phagocytic cells for defense against bacterial and fungal infections; bone marrow must produce approximately 10 x 10(9) neutrophils/kg/d to maintain normal blood neutrophil counts. Production of neutrophils depends on myeloid growth factors, particularly granulocyte colony-stimulating factor (G-CSF). After the original phase of development, researchers modified these growth factors to increase their size and delay renal clearance, increase their biologic potency, and create unique molecules for business purposes. Pegylated G-CSF is a successful product of these efforts. Researchers have also tried to identify small molecules to serve as oral agents that mimic the parent molecules, but these programs have been less successful. In 2006, the European Medicines Agency established guidelines for the introduction of new biologic medicinal products claimed to be similar to reference products that had previously been granted marketing authorization in the European community, called bio-similars. Globally, new and copied versions of G-CSF and other myeloid growth factors are now appearing. Some properties of the myeloid growth factors are similar to other agents, offering opportunities for the development of alternative drugs and treatments. For example, recent research shows that hematopoietic progenitor cells can be mobilized with a chemokine receptor antagonist, chemotherapy, G-CSF, and granulocyte macrophage colony-stimulating factor. Advances in neutrophil biology coupled with better understanding and development of myeloid growth factors offer great promise for improving the care of patients with cancer and many other disorders.