Stem cell factor and Interleukin-6, alone or in combination with granulocyte colony-stimulating factor, do not affect the growth of solid tumour cells lines

Hematopoietic growth factors (HGFs) are glycoproteins that control hemopoiesis. They have potential usefulness in a range of clinical conditions including the treatment of patients with myelosuppression induced by chemotherapy. Among HGFs, Stem Cell Factor (SCF) and Interleukin 6 (IL-6) are attracting interest for their capacity to stimulate early hematopoietic progenitors. Furthermore, their use in combination with late-acting growth factors with a more lineage-restricted potential (such as granulocyte colony-stimulating factor, G-CSF) might be expected to offer optimal marrow stimulation and usefulness in clinical oncology. Since non-hematopoietic malignant cells may express receptors for HGFs and respond to these peptides in vitro, we investigated clonal growth 3H-thymidine incorporation and cell cycle analysis by flow cytometry of 5 human solid tumor cell lines under the influence of SCF and IL-6 with or without G-CSF. Our experiments show that these cytokines have no effects on the proliferative capacity of the cell lines tested. Based on our and previously reported data, the use of these HGFs can be considered safe in cancer patients

Effects of granulocyte-macrophage colony-stimulating factor on small cell lung cancer cells

Nonhematopoietic malignant cells may express receptors for hematopoietic growth factors and respond to these peptides. The aim of the present study was to investigate whether small cell lung cancer (SCLC) cells may be stimulated to proliferate by hematopoietic growth factors such as granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-3 (IL-3), which are currently used in clinical trials in combination with cytotoxic chemotherapy. We studied two SCLC cell lines, H69 and N417. The effects of GM-CSF and IL-3 were evaluated by studying clonal growth, 3H-thymidine incorporation, BUDR/DNA bivariate flow cytometry, c-myc and N-myc oncogene expression, and myeloid surface markers. Our experiments show that both GM-CSF and IL-3 can increase 3H-thymidine incorporation and cloning efficiency and reduce DNA synthesis time of H69 and, to a lesser extent, N417 cells, supporting the hypothesis that hematopoietic growth factors can stimulate the growth of some malignant nonhematopoietic cells in vitro. Further in vitro and in vivo studies are needed to determine whether clinical trials applying these factors for bone marrow recovery after chemotherapy of solid tumors may be hazardous by potentially stimulating growth of remaining tumor tissue