Human GM-CSF in vivo: identification of the target cells and of their kinetics of response

Autocrine growth regulation by granulocyte colony-stimulating factor and granulocyte macrophage colony-stimulating factor in human gliomas with tumor progression

Granulocyte colony-stimulating factor (G-CSF) and granulocyte macrophage colony-stimulating factor (GM-CSF) and/or their receptors are increasingly detected in solid human tumors, although little is known about their function in tumor growth and invasion. We analyzed RNA and protein expression of both factors and their receptors in 22 human gliomas (WHO grade II, III, and IV) and derived cell cultures. G-CSF, GM-CSF, and/or their receptors were expressed in all tumors and derived cell cultures, but coexpression of both factors and receptors was almost exclusively found in grade IV glioblastomas and thus correlated with advanced tumor stage. The functional significance of G-CSF and GM-CSF as regulators for glioma cells was demonstrated by 1) stimulation of proliferation and migration in tumor cells expressing one or both receptors by the corresponding factor; 2) inhibition of growth and migration of glioma cells expressing G-CSF, GM-CSF, and their receptors by neutralizing antibodies to both factors. These results indicate a significant role for both factors in the autocrine regulation of growth and migration in late-stage malignant gliomas and suggest a shift from paracrine to autocrine regulation with tumor progression. The implication of G-CSF and GM-CSF in glioblastoma growth regulation could make these factors further prognostic indicators and raises questions concerning their use in cancer therapy.

Hematopoietic growth factors in autologous transplantation

Hematopoietic growth factors (HGFs) sustain the survival, proliferation and differentiation of hematopoietic stem cells and some functions of mature blood cells. In man several HGFs have been characterised and cloned so far, and this has allowed investigators to confer the rationale for the clinical application of these molecules in hematology and oncology. In particular G-CSF and GM-CSF are currently utilised to abrogate the hematological toxicity of chemotherapy for standard and dose-intensified therapy, neutropenia following bone marrow and peripheral blood stem cell transplantation. Moreover there has recently been great interest in the ex vivo expansion of hematopoietic stem and progenitor cells for a variety of applications, such as in vitro tumor cell purging or for reducing the volume of blood processed by the leukapheresis. Several combinations of HGFs have been described to sustain the ex vivo survival and proliferation of these cells disclosing new opportunities in the field of stem cells transplants.