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.

Tissue inhibitor of metalloproteinases 1 is an autocrine and paracrine survival factor, with additional immune-regulatory functions, expressed by Hodgkin/Reed-Sternberg cells.

Tissue inhibitor of metalloproteinases (TIMP)-1 and TIMP-2 are proteins with proteinase-inhibiting and cytokine properties. TIMP-1 is active primarily in B cells and B-cell lymphomas, whereas TIMP-2 expression is restricted to T cells. The expression of TIMP-1 and TIMP-2 in lymph nodes from patients with Hodgkin disease (HD) and in Hodgkin-derived cell lines was investigated. In situ hybridization showed TIMP-1 RNA expression in 3% to 80% of Hodgkin/Reed-Sternberg (H/R-S) cells from 14 of 15 patients, with results in one patient being at the lowest detection limit; no expression of TIMP-2 in H/R-S cells; and only weak expression of TIMP-2 in reactive lymphoid tissue. Production of TIMP-1 protein by H/R-S cells was accordingly found on immunohistochemical analysis of lymph nodes from patients with HD. There was only low expression of matrix metalloproteinase (MMP)-2, which is mainly inhibited by TIMP-2; no expression of MMP-1 and MMP-3 in reactive lymphoid tissue; and no expression of these MMPs in H/R-S cells. Thus, TIMP-1 expression in lymph nodes was not correlated with metalloproteinase expression. Five of 7 Hodgkin-derived cell lines expressed TIMP-1 at the protein level. Only one of these cell lines expressed TIMP-2, at the lowest detection limit. TIMP-1 levels in plasma from patients with HD were within the same range as those in plasma from healthy controls. Recombinant human TIMP-1 inhibited induced cell death in Hodgkin-derived cell lines in vitro. TIMP-1 and TIMP-2 inhibited T-cell cytotoxicity against autologous cells presenting tumor-associated antigens and in allogeneic mixed lymphocyte cultures. Thus, TIMP-1, aside from its role in proteinase equilibrium, is an autocrine and paracrine survival factor for H/R-S cells and an immunosuppressive protein expressed in Hodgkin lymphomas.