Modulation of interferon receptor expression during combination beta ser-interferon and gamma-interferon treatment of human colon carcinoma cells.
Combination treatment of SKCO1 human colon carcinoma cells with beta ser-interferon (IFN-beta ser) and gamma-interferon (IFN-gamma) results in a synergistic antiproliferative effect. The role of IFN-beta ser and IFN-gamma receptor modulation was investigated as a possible mechanism for this response. IFN-gamma (0.05-50 ng/ml) pretreatment of SKCO1 cells for 24 h decreased specific binding of 125I-IFN-beta ser by 35-60%. Scatchard analysis of binding data obtained following 24-h treatment with 5 ng/ml IFN-gamma showed that this reduction in binding was due to a decreased receptor affinity (control cells, Kd = 46 +/- 1.6 pM; IFN-gamma-treated cells, Kd = 106 +/- 6 pM, n = 2) rather than a significant change in receptor number (receptor number/control cell = 1214 +/- 471, receptor number/IFN-gamma treated cell = 1118 +/- 153, n = 2). In contrast, pretreatment of SKCO1 cells with IFN-beta ser (5 ng/ml) resulted in slight (10-35%) increases in 125I-IFN-gamma-specific binding. Scatchard analysis of binding data obtained following 24-h treatment with 5 ng/ml IFN-beta ser showed a decrease in binding affinity (control cells, Kd = 28 +/- 7 pM; IFN-beta ser-treated cells, Kd = 38 +/- 7 pM, n = 2) and a 32% increase in IFN-gamma receptor sites (receptor number/control cell = 4257 +/- 464, receptor number/IFN-beta ser-treated cell = 5570 +/- 730; n = 2). 125I-IFN-gamma internalization studies performed at 37 degrees C confirmed the cell surface binding assays; IFN-beta ser-treated cells internalized 30-50% more labeled IFN-gamma than untreated cells. However, it is unlikely that differences in binding and internalization of this magnitude play a primary role in the synergistic antiproliferative effect of IFN-gamma with IFN-beta ser in SKCO1 cells. Biochemical modulation at sites distal to the ligand receptor interaction should be investigated.
Schiller
J H
JH
University of Wisconsin Clinical Cancer Center, Madison 53792.
Bushmeyer
S M
SM
Ruzicka
F J
FJ
Princler
G L
GL
Faltynek
C R
CR
Borden
E C
EC
D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D003110:Colonic Neoplasms; D015536:Down-Regulation / Q000187:drug effects; D006801:Humans; D007370:Interferon Type I / Q000378:metabolism / Q000494:pharmacology*; D000068556:Interferon beta-1a; D000068576:Interferon beta-1b; D016899:Interferon-beta; D007371:Interferon-gamma / Q000378:metabolism / Q000494:pharmacology*; D007700:Kinetics; D011971:Receptors, Immunologic / Q000096:biosynthesis* / Q000187:drug effects / Q000378:metabolism; D017471:Receptors, Interferon; D011994:Recombinant Proteins / Q000378:metabolism / Q000494:pharmacology*; D014407:Tumor Cells, Cultured / Q000166:cytology / Q000187:drug effects / Q000276:immunology*
D007370:Interferon Type I; D011971:Receptors, Immunologic; D017471:Receptors, Interferon; D011994:Recombinant Proteins; D000068576:Interferon beta-1b; D016899:Interferon-beta; D007371:Interferon-gamma; D000068556:Interferon beta-1a