D-factor: modulation of expression in fibroblasts

Regulatory elements of the leukaemia inhibitory factor (LIF) promoter in murine bone marrow stromal cells

Leukaemia inhibitory factor (LIF) plays an important role as a haematopoietically active cytokine. As described earlier in a murine model, interleukin 1 (IL-1) induced LIF mRNA and protein expression. We utilized the murine cell line +/+-1.LDA11 to further define regulatory mechanisms of LIF expression in bone marrow stromal cells. The production of LIF mRNA is stimulated by IL-1beta, TNF-alpha, and the cAMP analogue 8-bromoadenosine 3':5'-monophosphate (8BrcAMP). LIF mRNA expression is controlled at the transcriptional level. Different fragments from -542 to -45 bp 5' upstream of the transcriptional start site of the murine LIF gene were fused to the luciferase gene. All LIF-promoter luciferase constructs exhibited constitutive luciferase activity under serum free conditions. The level of luciferase activity decreased with LIF-promoter constructs of less than 249 bp (pLIF249) in size. When tested with the 314 bp LIF-promoter construct, incubation of stromal cells with IL-1beta (500 U/ml) resulted in a 1.57-fold stimulation, with TNF-alpha (500 U/ml) in 2.06-fold stimulation, and with 8BrcAMP (0.5 mM) in a 3. 42-fold stimulation of luciferase activity. By testing different deletion mutants we could narrow the IL-1 and TNF-alpha responsive promoter areas to the region -249 to -145 bp and the 8BrcAMP responsive area from -145 to -82 bp. Mobility shift experiments revealed that nuclear proteins from stromal cells form a DNA-protein complex by binding to the region from -249 to -145 bp of the LIF promoter.

Inactivation of the DCC tumor suppressor gene in a B-cell lymphoma cell line with the alteration of chromosome 18

A B-cell lymphoma cell line, designated KML-1, was established from pleural effusion of a patient with non-Hodgkin's lymphoma of large-cell type. The lymphoma arose in the pelvis and ran an aggressive clinical course. Chromosome analysis of the cell line exhibited a complex karyotype including the loss of chromosome 18. To evaluate the molecular events in the cell line that may be associated with the development of the lymphoma, we investigated the expression and/or alterations of several classes of human genes, including oncogenes, tumor suppressor genes, and cytokine genes. The expression of the DCC (deleted in colorectal cancer) gene, located on the chromosome 18q21, was extremely reduced in KML-1 cell line, as compared with that in a normal spleen tissue and other 4 lymphoma cell lines by the reverse transcription-polymerase-chain-reaction (RT-PCR) method. This finding suggests that inactivation of the DCC gene might play a role in the pathogenesis of the case of lymphoma.

Leukaemia inhibitory factor and interleukin 6 are expressed at very low levels in the normal adult mouse and are induced by inflammation

We have assessed the limitations of the polymerase chain reaction (PCR) as a semiquantitative technique for assessing very low level gene expression. Using PCR, the in vivo expression patterns of the cytokines Leukaemia Inhibitory Factor (LIF) and Interleukin 6 (IL-6) in the normal adult mouse, have been examined. We show that both LIF and IL-6 mRNA are constitutively expressed, albeit at extremely low levels, in most tissues. While it is unclear whether this low level of expression is of biological significance, it is possible that it reflects a local mode of action of these potent polyfunctional molecules. Lipopolysaccharide, the bacterial cell wall product responsible for endotoxic shock, when administered in vivo, was capable of inducing the expression of both LIF and IL-6 in all of the tissues examined. In addition, LIF and IL-6 expression was induced in lung tissue by in vitro culturing in serum-free media. This induction of LIF and IL-6, by LPS and culturing, may reflect the role of these molecules as mediators of the acute phase response to tissue damage.