Growth inhibition and induction of apoptosis in acute myeloid leukemia cells by new indolinone derivatives targeting fibroblast growth factor, platelet-derived growth factor, and vascular endothelial growth factor receptors.

In acute myeloid leukemia (AML), receptor tyrosine kinase ligands promote growth and survival and contribute to AML-associated marrow neoangiogenesis. We have tested simultaneous inhibition of vascular endothelial growth factor, fibroblast growth factor, and platelet-derived growth factor receptor signaling by novel indolinone derivatives using 14 myeloid, including 11 human leukemic, cell lines. Compounds inhibited colony formation of all cell lines in a dose-dependent fashion. Inhibitory concentrations for 50% of the colony formation/survival (IC50) for BIBF1000 were <100 nmol/L for 3 of 11,

Receptor for platelet-activating factor (PAF) is not detectable by flow cytometry on the surface of myeloid leukemic cells.

Flow cytometry was applied to test for platelet-activating-factor receptor (PAF-R) presence on the membranes of acute myeloid leukemia (AML) cells. We have used six human AML cell lines and freshly taken density gradient separated blasts from the bone marrow of ten AML patients covering the majority of French-American-British (FAB) subtypes. Additionally, we have used one histiocytic lymphoma cell line and mature human granulocytes/monocytes as controls. Our results indicate lack of membrane PAF-R on AML of all FAB subtypes tested. This was particularly true for the more mature and differentiated subtypes M4 and M5, including monocytic cell elements, and the promyelocytic M3 AML. In contrast, membrane PAF-R could be easily detected in a histiocytic lymphoma cell line and mature granulocytes/monocytes from peripheral blood used as positive controls. In conclusion, this observation precludes the use of membrane PAF-R as an immunophenotypic marker for AML classification or detection of minimal residual disease.

Influence of keratinocyte growth factor on clonal growth of epithelial tumor cells, lymphoma and leukemia cells and on sensitivity of tumor cells towards 5-fluorouracil in vitro.

RhKGF is developed for prevention and treatment of chemotherapy- and radiation-induced epithelial damage in cancer patients. Little information exists on growth modulation of malignant cells by KGF. We have tested the anchorage-independent clonal growth of 35 human tumor and 22 lymphoma and leukemia cell lines in semisolid media with or without rhKGF. Growth of the majority of cell lines was not significantly influenced by rhKGF. Growth of 5 cell lines (2 lung, 1 stomach, 1 colorectal, 1 breast) was significantly stimulated by rhKGF. The effect was dose-dependent with significant stimulation at concentrations >1-10 ng/ml. Growth modulation was amplified by serum reduction and abolished by anti-hKGF antibodies. Responding cell lines expressed KGF receptor RNA and showed specific KGF-binding. To determine whether KGF-induced higher colony numbers represented cell divisions with resulting differentiation and growth arrest or self-renewal we performed experiments on serial plating efficacy of colony-derived tumor cells with or without continued presence of rhKGF. Results revealed KGF stimulation of colony formation as representing increase of cellular self-renewal. To test possible interaction of rhKGF with activity of cytotoxic drugs in clinical protocols, we have used combination protocols with 5-fluorouracil (5-FU). Results showed that rhKGF incubation before, after (or both) addition of 5-FU did not diminish the sensitivity of tumor cells to 5-FU cytotoxicity under serum concentrations relevant for the clinical situation. In conclusion, some epithelial tumor cells have receptors for KGF signaling for clonal growth. When considered in the planning of treatment protocols, this effect is unlikely to compromise chemotherapy sensitivity.