Effects of type-I and -II interferons on 90K antigen expression in ovarian carcinoma cells

Antigen 90K is produced by several tumor-cell lines and by patients with cancer. Its function has not yet been clarified, although recent reports suggest that it plays a role in the tumor-host relationship--for example by stimulation of natural killer and lymphokine-activated killer-cell activity. Previous studies have indicated that 90K expression may be under the influence of interferon-alpha. Here, we provide evidence that both interferon-alpha and -gamma can enhance the secretion of 90K and augment the level of specific mRNA expression in 3 ovarian carcinoma cell lines (OVCAR-3, HTB-77 and SKOV-6). However, interferon-gamma leads to depletion of cellular 90K whereas interferon-alpha increases both secreted and cellular 90K levels. In equimolar concentrations, Interferon-alpha was always superior to interferon-gamma in augmenting 90K protein or mRNA levels. Combinations of TNF with interferon-gamma were highly synergistic both in reducing cell proliferation and in increasing 90K secretion and mRNA expression. This synergism was seen to a lesser extent with interferon-alpha.