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- Hallbeck, Anna-Lotta, et al.
(författare)
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Interleukin-6 enhances transforming growth factor-alpha mRNA expression in macrophage-like human monocytoid (U-937-1) cells
- 2001
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Ingår i: Bioscience Reports. - 0144-8463 .- 1573-4935. ; 21:3, s. 325-339
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Tidskriftsartikel (refereegranskat)abstract
- We have previously reported that the human monocytoid cell line U-937-1 constitutively expresses transforming growth factor-alpha (TGF-α) and that the steady-state levels of TGF-α mRNA as well as TGF-α protein release increase when U-937-1 cells are differentiated towards monocytes/macrophages. Interleukin-6 (IL-6), which has been shown to have growth-stimulatory effects on a number of cell types, has recently been shown to enhance TGF-α expression in keratinocytes. In the present study we investigated whether TGF-α expression in macrophage-like cells could be regulated by IL-6 using U-937-1 cells as a model system of monocyte/macrophage differentiation. U-937-1 cells were differentiated with retinoic acid (RA), vitamin D3 (Vit-D3) or phorbol-12-myristate-13-acetate (PMA) for 4 days and were then treated with human recombinant IL-6 (1000 IU/ml) for up to 24 hr. Northern blot analysis revealed that cells differentiated with PMA, inducing the phenotype of a secretory macrophage, markedly increased their TGF-α mRNA levels (2.7-fold) when treated with IL-6; the response was maximal at 6 hr and remained high at 12 hr. The expression of the TGF-α gene was accompanied by release of TGF-α protein into the cell culture medium, irrespective of differentiating agent, as demonstrated by enzyme-linked immunosorbent assay (ELISA), as well as by surface expression of pro-TGF-α as determined by indirect immunofluorescent cytometry. However, the superinduction of the TGF-α gene by IL-6 in cells differentiated with PMA was not accompanied by any increase in TGF-α protein release or pro-TGF-α surface expression. We conclude that since IL-6 causes increased steady-state levels of TGF-α mRNA in macrophage-like cells, it may prime these cells for production of this growth factor. Furthermore, we have shown that the IL-6 receptor complex is functional in U-937-1 cells induced to differentiate towards a secretory macrophage by treatment with PMA.
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- Wolfraim, Lawrence A, et al.
(författare)
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Loss of Smad3 in acute T-cell lymphoblastic leukemia
- 2004
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Ingår i: New England Journal of Medicine. - 0028-4793 .- 1533-4406. ; 351:6, s. 552-559
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The receptors for transforming growth factor β (TGF-β) and their signaling intermediates make up an important tumor-suppressor pathway. The role of one of these intermediates - Smad3 - in the pathogenesis of lymphoid neoplasia is unknown. METHODS: We measured Smad3 messenger RNA (mRNA) and protein in leukemia cells obtained at diagnosis from 19 children with acute leukemia, including 10 with T-cell acute lymphoblastic leukemia (ALL), 7 with pre-B-cell ALL, and 2 with acute nonlymphoblastic leukemia (ANLL). All nine exons of the SMAD3 gene (MADH3) were sequenced. Mice in which one or both alleles of Smad3 were inactivated were used to evaluate the role of Smad3 in the response of normal T cells to TGF-β and in the susceptibility to spontaneous leukemogenesis in mice in which both alleles of the tumor suppressor p27Kip1 were deleted. RESULTS: Smad3 protein was absent in T-cell ALL but present in pre-B-cell ALL and ANLL. No mutations were found in the MADH3 gene in T-cell ALL, and Smad3 mRNA was present in T-cell ALL and normal T cells at similar levels. In mice, the loss of one allele for Smad3 impairs the inhibitory effect of TGF-β on the proliferation of normal T cells and works in tandem with the homozygous inactivation of p27Kip1 to promote T-cell leukemogenesis. CONCLUSIONS: Loss of Smad3 protein is a specific feature of pediatric T-cell ALL. A reduction in Smad3 expression and the loss of p27Kip1 work synergistically to promote T-cell leukemogenesis in mice.
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