CONTROL OF CELL-PROLIFERATION BY EMBRYONAL-ORIGIN FACTORS

Embryogenesis can be paralleled and contrasted with cancerous cell pro liferation; both embryogenesis and cancer are associated with extremel y rapid cell proliferation. However, unlike cancer, embryogenesis is c haracterized by a delicate balance of proliferative and anti-prolifera tive processes. We have found two chromatographically separated fracti ons derived from human embryonal neural tissue extracts that significa ntly suppress the proliferation of human breast cancer cells. The redu ction in cell number was time dependent, with maximal inhibition (70%) observed after 4 days of incubation while maintaining cell viability. The anti-proliferative effect was also evidenced by decreased [H-3]-t hymidine incorporation. Significant inhibition of proliferation of ost eosarcoma, fibrosarcoma, and Balb/c 3T3 cell lines was also obtained w ith a low concentration of the active fractions. Embryonal factors inh ibited mouse and rat cell lines, indicating cross-species effectivenes s. The SDS-PAGE of the biologically active similar to 10.7 kDa region revealed several protein bands, while the biologically active similar to 4.5 kDa fraction contained only weakly stainable bands. Thus, the e mbryo contains factors that control the proliferation of malignant cel ls. These potent and possibly novel compounds should be investigated f or their potential therapeutic role in cancer and other proliferative disorders.