Nitric oxide from rat liver sinusoidal endothelial cells induces apoptosis in IFN gamma-sensitized CC531s colon carcinoma cells.
OBJECTIVE
Investigation of apoptosis is pivotal in searching for mechanisms that eliminate colon cancer cells getting trapped in liver sinusoids at the time of surgical removal of the primary tumor. This study focuses on nitric oxide (NO), Fas/FasL and the involvement of interferon-gamma (IFNgamma) in liver sinusoidal endothelial cells (LSECs) and in the colon carcinoma cell line CC531s.


METHODS
Apoptosis was quantified and visualized in vitro by specific DNA fragmentation, specific staining and electron microscopy. In vivo experiments were also conducted.


RESULTS
In co-cultures of LSECs with CC531s, apoptosis of CC531s was observed only when they were pre-treated with IFNgamma, and was unaffected by blocking the Fas/FasL pathway. However, LSECs continuously produced NO, and apoptosis was inhibited by NO-inhibitors (NMMA and dexamethasone). When IFNgamma-sensitized CC531s were injected into rats, liver weight was lower, in contrast to control conditions where liver weight was higher.


CONCLUSIONS
(i) LSECs induce apoptosis in IFNgamma-sensitized CC531s in vitro; (ii) LSECs express FasL; (iii) Fas on CC531s becomes active after IFNgamma-treatment; however, (iv) blocking the Fas/FasL pathway had no effect; (v) apoptosis was inhibited by NO-inhibitors; (vi) the immune system uses this IFNgamma-activated pathway to support LSECs in killing tumor cells.
Vekemans
Katrien
K
Laboratory for Cell Biology and Histology, Free University Brussels, Laarbeeklaan 103, B-1090 Brussels-Jette, Belgium. kvekeman@cyto.vub.ac.be
Braet
Filip
F
Muyllaert
David
D
Wisse
Eddie
E
D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D002450:Cell Communication; D018920:Coculture Techniques; D003110:Colonic Neoplasms / Q000473:pathology*; D003907:Dexamethasone / Q000494:pharmacology; D042783:Endothelial Cells / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D053222:Fas Ligand Protein; D005938:Glucocorticoids / Q000494:pharmacology; D007371:Interferon-gamma / Q000494:pharmacology*; D008099:Liver / Q000473:pathology; D008113:Liver Neoplasms / Q000188:drug therapy / Q000556:secondary*; D008562:Membrane Glycoproteins / Q000235:genetics; D009569:Nitric Oxide / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017208:Rats, Wistar; D014407:Tumor Cells, Cultured; D019014:fas Receptor / Q000235:genetics; D019323:omega-N-Methylarginine / Q000494:pharmacology
D000970:Antineoplastic Agents; D004791:Enzyme Inhibitors; D053222:Fas Ligand Protein; C505662:Faslg protein, rat; D005938:Glucocorticoids; D008562:Membrane Glycoproteins; D012333:RNA, Messenger; D019014:fas Receptor; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D003907:Dexamethasone; D007371:Interferon-gamma