ANTITUMOR ACTIONS OF INTERFERON-GAMMA AND INTERLEUKIN-1-BETA ON HUMANPAPILLARY THYROID-CARCINOMA CELL-LINES

To test the hypothesis that interferon-gamma (IFN gamma) and interleuk in-1 beta (IL-1 beta) possess antitumor activity on human papillary th yroid carcinoma cells, we studied the in vitro effects of IFN gamma an d IL-1 beta on the proliferation and invasiveness of two human PTC cel l lines, TPC-1 (TP) and NPA (NP) cells. TP and NP cells were treated w ith various concentrations ofIFN gamma and IL-1 beta alone and in comb ination. Cell proliferation was assessed by [H-3]thymidine incorporati on and cell number measurement. Tumor cell invasion was assessed by th e ability of cells to penetrate through a Matrigel membrane. Both IFN gamma and IL-1 beta inhibited [H-3]thymidine incorporation into TP cel ls in a dose-dependent manner and decreased TP cell number. In NP cell s, treatment with IFN gamma and IL-1 beta also decreased [H-3]thymidin e incorporation and cell number. The inhibitory effects of IFN gamma a nd IL-1 beta on tumor cell proliferation were additive in both cell li nes. In the invasion experiments, IFN gamma and IL-1 beta reduced the invasiveness of TP and NP cells. Again, the inhibitory effects of IFN gamma and IL-1 beta on tumor cell invasion were additive in both cell lines. In summary, the results showed that both IFN gamma and IL-1 bet a are potent inhibitors of the proliferation and invasiveness of TP an d NP cells. The additive effects of IFN gamma and IL-1 beta are eviden ce that they act through different pathways. Our findings suggest that IFN gamma and IL-1 beta are two of the anticancer factors that act to suppress the proliferation and reduce the invasive potential of human papillary thyroid carcinoma cells.