title: Interleukin-2 enhances susceptibility of colon cancer cells to FasR mediated apoptosis by up-regulating Fas receptor level and down-regulating FAP-1 expression.
abstract: Colon cancer cells are resistant to FasR-mediated apoptosis, which contributes to their evasion from immune attack by CTLs and NK cells. FasR refractoriness of the malignancies was reported to result from loss of Fas receptors and overepression of Fas-associated phosphatase-1 (FAP-1). Therefore, we investigated the effects of recombinant IL-2 on FasR and FAP-1 expression of colon cancer cells, and its influence on the sensitivity of colon cancer cells to FasR-mediated apoptosis. Colon cancer cell lines SW480, HT-29 and CaCo2 were incubated with IL-2 for different periods of time. Sensitivity of the cells to FasR-mediated apoptosis was assessed by measuring their apoptosis after treated with agonistic anti-FasR MAb CH-11. Additionally, Fas receptor levels were examined by immunofluorescence and mRNA expression of FasR and FAP-1 was investigated by RT-PCR: IL-2 incubation increased CH11-induced apoptosis in all colon cancer cell lines in a time-dependent manner. In parallel, IL-2 up-regulated Fas receptor expression on HT29 and CaCo2 cells at both protein and mRNA levels, which were low before treatment, while it served to maintain high expression of FasR on SW480 cells. Additionally, IL-2 down-regulated FAP-1 mRNA expression on SW480 and CaCo2 cells, which was high before treatment. However, low expression of FAP1 on HT-29 cells remained stable after IL-2 treatment. Thus, IL-2 enhances susceptibility of colon cancer cells to FasR-mediated apoptosis by up-regulating Fas receptor levels and by down-regulating FAP-1 expression, which accounts for its therapeutic effects on abolishing immune evasion in colon cancer cells.
authors.affiliation: Dept Medicine, University Hospital Essen, Germany.
authors.forename: E
authors.initials: E
authors.lastname: Song
authors.forename: J
authors.initials: J
authors.lastname: Chen
authors.forename: B
authors.initials: B
authors.lastname: Antus
authors.forename: M
authors.initials: M
authors.lastname: Wang
authors.forename: Y
authors.initials: Y
authors.lastname: Xie
authors.forename: H
authors.initials: H
authors.lastname: Yao
authors.forename: M S
authors.initials: MS
authors.lastname: Exton