The role of oxygen-derived free radicals and nitric oxide in cytokine-induced antiproliferation of pancreatic cancer cells.
BACKGROUND
Pancreatic cancer cells are susceptible to antiproliferative effects of cytokines such as tumor necrosis factor-alpha (TNF-alpha). However, little is known about the mechanisms involved.


OBJECTIVE
To determine the mechanisms of the antiproliferative effects of TNF-alpha on pancreatic cancer cells.


RESULTS
In the current study, four of five pancreatic cancer cell lines tested were responsive to the antiproliferative effects of TNF-alpha. In two cell lines, the effects of TNF-alpha were completely abolished by superoxide dismutase, suggesting that superoxide anion mediates the effects. Further, inhibition of nitric oxide (NO) synthase by L-NAME potentiated the TNF-alpha response, suggesting a protective role for endogenously produced NO in these two cell lines. MiaPaCa-2 cells, which were unresponsive to the antiproliferative effects of TNF-alpha, produced five times more nitrite than the other cell lines. Treatment of MiaPaCa-2 cells with interferon-gamma (IFN-gamma) increased inducible nitric oxide synthase mRNA as shown by reverse transcription-polymerase chain reaction. This induction was potentiated by TNF-alpha and further enhanced by a combination of three cytokines (INF-gamma, TNF-alpha, and interleukin 1-beta (IL-1beta). This combination of cytokines increased nitrite accumulation fourfold and inhibited the proliferation of this resistant cell line. These effects were prevented by L-NAME.


CONCLUSIONS
These studies suggest that TNF-alpha inhibits proliferation of pancreatic cancer cells by increasing the production of superoxide anion and that endogenously produced NO protects against this effect. In addition, there is a direct correlation between the amount of NO produced and resistance to TNF-alpha in the only resistant cell line. In contrast, treatment with a combination of IFN-gamma, TNF-alpha and IL-1beta upregulates inducible nitric oxide synthase, and the resulting markedly enhanced NO production inhibits pancreatic cancer cell growth. This pathway may provide a valuable target for therapy of this devastating disease.
Thomas
William J
WJ
Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, Nebraska, U.S.A.
Thomas
Deborah L
DL
Knezetic
Joseph A
JA
Adrian
Thomas E
TE
D000230:Adenocarcinoma; D000970:Antineoplastic Agents / Q000494:pharmacology; D021441:Carcinoma, Pancreatic Ductal; D002455:Cell Division / Q000187:drug effects; D016207:Cytokines / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016166:Free Radical Scavengers / Q000494:pharmacology; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology; D007375:Interleukin-1 / Q000494:pharmacology; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000235:genetics / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III; D009573:Nitrites / Q000378:metabolism; D010190:Pancreatic Neoplasms; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D012333:RNA, Messenger / Q000032:analysis; D017382:Reactive Oxygen Species / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014407:Tumor Cells, Cultured / Q000166:cytology / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D000970:Antineoplastic Agents; D016207:Cytokines; D004791:Enzyme Inhibitors; D016166:Free Radical Scavengers; D007375:Interleukin-1; D009573:Nitrites; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D014409:Tumor Necrosis Factor-alpha; D009569:Nitric Oxide; D007371:Interferon-gamma; C496314:NOS3 protein, human; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; D011493:Protein Kinase C; D019331:NG-Nitroarginine Methyl Ester