ISOLATION OF TUMOR-CELL GROWTH-INHIBITING FACTORS FROM A HUMAN RHABDOMYOSARCOMA CELL-LINE

  • 1 January 1985
    • journal article
    • research article
    • Vol. 45  (6) , 2689-2694
Abstract
Two types of growth-modulating factors were derived from the serum-free conditioned media of a human rhabdomyosarcoma cell line, A673. One type MW 18,000-22,000, competes for binding to epidermal growth factor receptors and enhances the growth of normal and tumor cells in soft agar. It has all of the biological properties ascribed to transforming growth factor type .alpha. (TGF.alpha.). A673 cells also produce factors which inhibit the growth of human tumor cells in soft agar and in monolayer cultures. These tumor cell growth-inhibiting factors (TIF) are acid- and heat-stable peptides. The major TIF activities have MW in the ranges of > 28,000, 18,000-22,000, 10,000-16,000 and 5000-10,000 and do not possess the antiviral activity associated with interferon. Partially purified preparations of TIF-1 (MW 10,000-16,000) inhibit the growth of all human tumor cell lines tested and stimulate the growth of normal human fibroblasts and epithelial cells in monolayer cultures. The growth of human lung carcinoma A549 cells in soft agar, which was enhanced by treatment with TGF.alpha. from A673-conditioned media, was inhibited by treatment with TIF-1 derived from the same media. The ratio of the 2 types of tumor cell-derived, growth-modulating factors (TIF and TGF.alpha.), which are antagonistic in their biological effects, may determine the capacity of tumor cells for anchorage-independent growth.

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