Studies on the action of apoptosis inducing factor derived from bovine colostrum

我们用离子交换层析从牛初乳中分离出部分纯化的部分组分，发现了一种细胞生长抑制因子。该因子可诱导小鼠肺成纤维细胞发生凋亡。众所周知，牛初乳中含有IGF-I，所以我们测量了该部分的IGF-I浓度。该组分含有约500 ng/mg的IGF-I蛋白。然后，用LM、L6和Balb/c 3T3三种细胞系检测了IGF-I对细胞增殖的影响。令人惊讶的是，IGF-I诱导了LM细胞的死亡，同时在低FCS条件下刺激了L6和Balb/c 3T3细胞的增殖。酪氨酸激酶抑制剂Herbimycin A可抑制IGF-I诱导的LM细胞死亡，提示IGF-I可诱导LM细胞死亡，其作用机制可能与激活酪氨酸激酶有关。

We found a cell-growth inhibiting factor in partially purified fraction from bovine colostrum using an ion-exchange chromatography. The factor induced apoptosis in mouse LM fibroblasts. It is well known that bovine colostrum contains IGF-I,so we measured IGF-I concentrations of the fraction. The fraction contained about 500ng/mg protein of IGF-I.Then, effects of IGF-I on cell proliferation were determined using three cell lines, LM,L6, and Balb/c 3T3 cells. To our surprise, IGF-I induced cell death of LM cells, while it stimulated proliferation of L6 and Balb/c 3T3 cells in low FCS condition. Herbimycin A,a tyrosine kinase inhibitor, inhibited cell death induced by IGF-I in LM cells.These data suggests that IGF-I induces cell death of LM cells and the action involves activation of tyrosine kinase.