Survival of the myeloid progenitor cell line FDC-P1 is prolonged by interferon-gamma or interleukin-4

The effect of environmental chemicals on the tumor microenvironment

Potentially carcinogenic compounds may cause cancer through direct DNA damage or through indirect cellular or physiological effects. To study possible carcinogens, the fields of endocrinology, genetics, epigenetics, medicine, environmental health, toxicology, pharmacology and oncology must be considered. Disruptive chemicals may also contribute to multiple stages of tumor development through effects on the tumor microenvironment. In turn, the tumor microenvironment consists of a complex interaction among blood vessels that feed the tumor, the extracellular matrix that provides structural and biochemical support, signaling molecules that send messages and soluble factors such as cytokines. The tumor microenvironment also consists of many host cellular effectors including multipotent stromal cells/mesenchymal stem cells, fibroblasts, endothelial cell precursors, antigen-presenting cells, lymphocytes and innate immune cells. Carcinogens can influence the tumor microenvironment through effects on epithelial cells, the most common origin of cancer, as well as on stromal cells, extracellular matrix components and immune cells. Here, we review how environmental exposures can perturb the tumor microenvironment. We suggest a role for disrupting chemicals such as nickel chloride, Bisphenol A, butyltins, methylmercury and paraquat as well as more traditional carcinogens, such as radiation, and pharmaceuticals, such as diabetes medications, in the disruption of the tumor microenvironment. Further studies interrogating the role of chemicals and their mixtures in dose-dependent effects on the tumor microenvironment could have important general mechanistic implications for the etiology and prevention of tumorigenesis.

Distinct methylation of the interferon gamma (IFN-gamma) and interleukin 3 (IL-3) genes in newly activated primary CD8+ T lymphocytes: regional IFN-gamma promoter demethylation and mRNA expression are heritable in CD44(high)CD8+ T cells

Differential genomic DNA methylation has the potential to influence the development of T cell cytokine production profiles. Therefore, we have conducted a clonal analysis of interferon (IFN)-gamma and interleukin (IL)-3 gene methylation and messenger (m)RNA expression in primary CD8+ T cells during the early stages of activation, growth, and cytokine expression. Despite similar distributions and densities of CpG methylation sites, the IFN-gamma and IL-3 promoters exhibited differential demethylation in the same T cell clone, and heterogeneity between clones. Methylation patterns and mRNA levels were correlated for both genes, but demethylation of the IFN-gamma promoter was widespread across >300 basepairs in clones expressing high levels of IFN-gamma mRNA, whereas demethylation of the IL-3 promoter was confined to specific CpG sites in the same clones. Conversely, the majority of clones expressing low or undetectable levels of IFN-gamma mRNA exhibited symmetrical methylation of four to six of the IFN-gamma promoter CpG sites. Genomic DNA methylation also has the potential to influence the maintenance or stability of T cell cytokine production profiles. Therefore, we also tested the heritability of IFN-gamma gene methylation and mRNA expression in families of clones derived from resting CD44(low)CD8+ T cells or from previously activated CD44(high)CD8+ T cells. The patterns of IFN-gamma gene demethylation and mRNA expression were faithfully inherited in all clones derived from CD44(high) cells, but variable in clones derived from CD44(low) cells. Overall, these findings suggest that differential genomic DNA methylation, including differences among cytokine genes, among individual T cells, and among T cells with different activation histories, is an important feature of cytokine gene expression in primary T cells.

Synergy among erythropoietin, interleukin 3, stem cell factor (c-kit ligand) and interferon-gamma on early human hematopoiesis

The stimulatory effect of interferon-gamma (IFN-gamma) on human early hematopoiesis was investigated using CD34+ cells that were purified from peripheral blood as a target. In the presence of human interleukin 3 (IL-3) and stem cell factor (SCF), the growth of colony forming units for granulocyte/macrophage (CFU-GM) in serum-free methylcellulose culture was enhanced up to 5.5-fold over baseline colony formation (n = 10, mean +/- SE, 3.18 +/- 1.00) by coculture with 2.5 x 10(3) U/ml IFN-gamma, whereas burst forming units-erythroid (BFU-E) growth induced by additional erythropoietin (Epo) was reduced dose-dependently. Liquid-suspension culture of the target cells for 24 h with IFN-gamma before secondary plating in serum-free methylcellulose resulted in a marked increase in the colony numbers; 3.62 +/- 1.04-fold for CFU-GM and 5.72 +/- 2.32-fold for BFU-E (n = 5). The effect was most striking in the growth of erythroid lineage supported by Epo alone in serum-free culture. Delayed addition of IFN-gamma between days 4 and 7 of methylcellulose culture suppressed CFU-GM growth, but not that of BFU-E. These results suggest that IFN-gamma is an essential cytokine that affects human hematopoiesis and exerts a bimodal effect on stem cell maturation; potentiating or replacing the effect of early-acting cytokines such as SCF or IL-3, and suppressing the growth of matured progenitor cells.