IMR Press / FBL / Volume 9 / Issue 1 / DOI: 10.2741/1252

Frontiers in Bioscience-Landmark (FBL) is published by IMR Press from Volume 26 Issue 5 (2021). Previous articles were published by another publisher on a subscription basis, and they are hosted by IMR Press on imrpress.com as a courtesy and upon agreement with Frontiers in Bioscience.

Article
Expression of Fas ligand is not a main mechanism used by tumors to counteract antitumor immunity
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1 Division of Gastroenterology, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109, USA
Front. Biosci. (Landmark Ed) 2004, 9(1), 448–456; https://doi.org/10.2741/1252
Published: 1 January 2004
Abstract

The role of Fas ligand (FasL) in tumor immune privilege is controversial. In this study, 22 human tumor cell lines reported to be FasL+ were reevaluated by Western blot analysis, ELISA, and a functional assay. None of the cells lines expressed FasL. To assess whether human tumors express FasL in vivo, susceptibility to FasL-mediated killing was evaluated. About 75% of the 22 tumors tested were sensitive to FasL-mediated apoptosis, suggesting, therefore, that only about 25% could possibly express FasL. To investigate whether "FasL+" human tumor cells could suppress the proinflammatory effects of FasL in vivo, FasL transfectants were generated from two prototype "FasL+" tumor cell lines. The transfectants expressing FasL were rejected by SCID mice. In contrast, all the mice inoculated with parental tumor cells developed large tumors. These results suggested that human tumor cells that express FasL and resist both FasL-mediated apoptosis and inflammation are rare or nonexistant. We concluded that FasL expression is not a main mechanism that tumors use to counteract antitumor immunity.

Keywords
CD95
Ligand
Tumor
Apoptosis
Inflammation
Antitumor Immunity
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