Isolation of a proliferation inhibitor factor from uterine myomatosis fibroblasts

In this work, we report the isolation of a factor from the culture supernatant of confluent fibroblasts from human cervix with the diagnosis of uterine myomatosis. This factor possesses the capacity to inhibit the proliferation of normal fibroblasts. The proliferation inhibitor factor (PIF) was purified from the culture supernatant by precipitation with 80% ammonium sulfate, and by molecular sieve chromatography. Our results indicate that PIF is a protein of 23 kDa, which is highly sensitive to trypsin treatment, and is thermolabile, since temperatures equal to, or above, 60 degrees C eliminate the protein activity in 15 to 20 min. Western blot analyses identified no cross reactions of the purified PIF with TGF-alpha, TNFalpha, IFNgamma, or IL-1beta, suggesting that PIF is a new protein belonging to the group of factors secreted by fibroblasts able to inhibit cellular proliferation.