Inhibition of mitogen stimulated growth of human colon cancer cells by interferon.

Aw Hamburger,K O'Donnell,Me Condon

doi:10.1038/bjc.1988.182

Abstract

Recombinant human interferon alpha inhibits growth of a human colon cancer cell line, Colo 205. To explore the mechanisms of IFN induced growth inhibition, quiescent Colo 205 cells were stimulated to proliferate in serum-free media by defined growth factors. Addition of insulin, transferrin and selenium (ITS) stimulated DNA synthesis, as measured by 3H-thymidine incorporation, in a dose-dependent manner. IFN-alpha (at concentrations greater than 100 U ml-1) inhibited ITS stimulated DNA synthesis by 63%. Inhibition of cell cycle traverse was confirmed by flow cytometric analysis. Although IFN inhibited growth of ITS-treated cells, steady state levels of c-myc mRNA remained above levels observed in unstimulated cells. IFN inhibited DNA synthesis only when added prior to mitogen stimulation. IFN, added 6 h after exposure of quiescent cells to ITS, failed to inhibit cell growth. Addition of increasing concentrations of ITS failed to overcome the IFN-induced growth inhibition. These results suggest IFN may inhibit cell growth in part by antagonizing the action of growth factors.

Highlights

The present study demonstrates that the growth of Colo 205 cells is dependent on insulin and transferrin
We report that recombinant IFN;c2 inhibits proliferation of Colo205 colon carcinoma cells and abolishes the mitogenic effect of insulin and transferrin
A 50% decrease in cell growth was observed at 125 U ml-1 of IFN (Figure 2)

Summary

Methods

ReagentsHuman recombinant IFNa-2 (1.7 x 108 units mg-1 protein) was a gift of Schering Corp. (Kenilworth, NJ). Human recombinant IFNa-2 (1.7 x 108 units mg-1 protein) was a gift of Schering Corp. Transferrin and selenium were obtained from either Sigma (St Louis, MO) or Collaborative Research (Sudbury, MA). Colo 205 cells (CCL 222) were obtained from the American Type Culture Collection (Rockville, MD). The cells were cultured in RPMI 1640 medium containing 10% (v/v) foetal bovine serum (FBS). The cells were used within 20 passages of the original frozen stock.

Results

Discussion

Conclusion