Role of hepatic non-parenchymal cells in the response of rat hepatocytes to the peroxisome proliferator nafenopin in vitro.

Induction of liver cancer by peroxisome proliferators such as nafenopin is frequently associated with increased liver growth, increased DNA synthesis and suppression of apoptosis. The cytokine, tumour necrosis factor alpha (TNF alpha), and non-parenchymal liver cells have been implicated in mediating the hepatic response to peroxisome proliferators. Here, we have investigated the dependency of the hepatocyte response to peroxisome proliferators on non-parenchymal cells, a major source of hepatic cytokines. Addition of non-parenchymal cells, or conditioned medium from non-parenchymal cell cultures, increased DNA synthesis (220% and 270% of control, respectively) and suppressed transforming growth factor beta(1)-induced hepatocyte apoptosis (32% and 54% of control, respectively). Removal of non-parenchymal cells from normal hepatocyte cultures prevented both the nafenopin- and TNF alpha-induced increase in DNA synthesis and suppression of hepatocyte apoptosis; this response was restored by returning non-parenchymal cells to the purified hepatocytes. TNF alpha was detected in the medium of non-parenchymal cell (3-15 pg/ml) and normal hepatocyte cultures (25-100 pg/ml) by bioassay using L929 cells. However, the contribution of TNF alpha released from non-parenchymal cells was small compared with that released spontaneously by hepatocytes. Nafenopin significantly increased the release of TNF alpha from non-parenchymal cells to 56 +/- 18 pg/ml, but had little effect on TNF alpha release by hepatocytes. However, the concentration of exogenous TNF alpha required to elicit a response in hepatocytes was 100 pg/ml and above. These data provide evidence that hepatic non-parenchymal cells are permissive for the growth response of hepatocytes in vitro to peroxisome proliferators and this may be mediated, at least in part by TNF alpha. However, the levels of TNF alpha released spontaneously or in response to peroxisome proliferators are insufficient per se to induce a growth response.

[1]  J. Peschon,et al.  Initiation of liver growth by tumor necrosis factor: deficient liver regeneration in mice lacking type I tumor necrosis factor receptor. , 1997, Proceedings of the National Academy of Sciences of the United States of America.

[2]  D. Friend,et al.  HIGH-YIELD PREPARATION OF ISOLATED RAT LIVER PARENCHYMAL CELLS , 1969, The Journal of cell biology.

[3]  T. V. van Berkel,et al.  In vivo and in vitro uptake and degradation of acetylated low density lipoprotein by rat liver endothelial, Kupffer, and parenchymal cells. , 1983, The Journal of biological chemistry.

[4]  B. Lake,et al.  Peroxisome proliferation and nongenotoxic carcinogenesis: commentary on a symposium. , 1991, Fundamental and applied toxicology : official journal of the Society of Toxicology.

[5]  S Kettle,et al.  Mechanistically-based Human Hazard Assessment of Peroxisome Proliferator-induced Hepatocarcinogenesis , 1994, Human & experimental toxicology.

[6]  R. Roberts,et al.  Species differences in response to peroxisome proliferators correlate in vitro with induction of DNA synthesis rather than suppression of apoptosis. , 1996, Carcinogenesis.

[7]  M. Pibiri,et al.  Liver cell proliferation induced by nafenopin and cyproterone acetate is not associated with increases in activation of transcription factors NF‐κB and AP‐1 or with expression of tumor necrosis factor α , 1997 .

[8]  G. Williams,et al.  Mechanism‐based Risk Assessment of Peroxisome Proliferating Rodent Hepatocarcinogens , 1996, Annals of the New York Academy of Sciences.

[9]  N. Macdonald,et al.  Induction of DNA replication by peroxisome proliferators is independent of both tumour necrosis factor (alpha) priming and EGF-receptor tyrosine kinase activity. , 1999, Journal of cell science.

[10]  J. Peters,et al.  Role of PPAR alpha in the mechanism of action of the nongenotoxic carcinogen and peroxisome proliferator Wy-14,643. , 1997, Carcinogenesis.

[11]  I. Kimber,et al.  Dermal tumour necrosis factor-alpha induces dendritic cell migration to draining lymph nodes, and possibly provides one stimulus for Langerhans' cell migration. , 1992, Immunology.

[12]  I. Rusyn,et al.  WY-14 643 rapidly activates nuclear factor kappaB in Kupffer cells before hepatocytes. , 1998, Carcinogenesis.

[13]  D. Germolec,et al.  Kupffer cells are causally responsible for the mitogenic effect of peroxisome proliferators. , 1997, Carcinogenesis.

[14]  J. Peters,et al.  Suppression of mouse hepatocyte apoptosis by peroxisome proliferators : role of PPARα and TNFα , 2000 .

[15]  J A Swenberg,et al.  Kupffer cell oxidant production is central to the mechanism of peroxisome proliferators. , 1999, Carcinogenesis.

[16]  I. Rusyn,et al.  Role of Kupffer cells in peroxisome proliferator-induced hepatocyte proliferation. , 1999, Drug metabolism reviews.

[17]  I. Rusyn,et al.  Peroxisome proliferator-activated receptor alpha is restricted to hepatic parenchymal cells, not Kupffer cells: implications for the mechanism of action of peroxisome proliferators in hepatocarcinogenesis. , 2000, Carcinogenesis.

[18]  L. Old,et al.  Tumor necrosis factor (TNF). , 1985, Science.

[19]  N. Macdonald,et al.  Suppression of apoptosis and induction of DNA synthesis in vitro by the phthalate plasticizers monoethylhexylphthalate (MEHP) and diisononylphthalate (DINP): a comparison of rat and human hepatocytes in vitro , 1999, Archives of Toxicology.

[20]  J. Peters,et al.  Tumour necrosis factor alpha (TNFalpha): role in suppression of apoptosis by the peroxisome proliferator nafenopin. , 2000, Cellular and molecular biology.

[21]  R. Roberts,et al.  Cytokines in non-genotoxic hepatocarcinogenesis. , 1999, Carcinogenesis.

[22]  G. Ciliberto,et al.  In vivo hepatocyte proliferation is inducible through a TNF and IL-6-independent pathway , 1998, Oncogene.

[23]  A. Gonzales,et al.  Regulation of apoptosis in mouse hepatocytes and alteration of apoptosis by nongenotoxic carcinogens. , 1998, Cell growth & differentiation : the molecular biology journal of the American Association for Cancer Research.

[24]  F. Gonzalez.  Recent update on the PPARα-null mouse , 1997 .