STIMULATION OF TUMOR-CELL GROWTH BY ALPHA-FETOPROTEIN

It has been recognized that alpha-fetoprotein (AFP), as an oncofetal a ntigen, is re-expressed in large amounts in adult tumor cells and serv es clinically useful purposes in tumor-marker assays. However, its bio logical activities are still undefined. In the present study, the abil ity of AFP to stimulate tumor-cell growth was observed by an in vitro experimental system. Mouse ascites cancer cells derived from hepatoma- 22(H-22) or Ehrlich ascites carcinoma(EAC) were extracted intraperiton eally and cultured in RPMI 1640 medium containing 10% newborn calf ser um for 48 hr. Cell growth was quantitated by a colorimetric assay usin g a MTT microculture tetrazolium dye. The results demonstrated that AF P significantly increased H-22-cell proliferation, with stimulation pe rcents of 122 to 156%. A similar growth-promoting effect of AFP was ob served using EAC cells, with stimulation percents of 86 to 210%. Moreo ver, the growth-stimulatory activity of AFP could be abrogated with an ti-AFP antibodies. In addition, 5-fluorouracil could obviously inhibit AFP-induced proliferation of H-22 or EAC cells in vitro. These result s suggest that AFP is associated with tumor-cell growth and may serve as an important target of tumor therapy. (C) 1998 Wiley-Liss, Inc.