Proliferation mechanism of protein-free culture

我们假设肿瘤细胞的自主增殖是先天性的，自分泌生长假说可能不适用于体外肿瘤细胞的自主性。根据这一假设，我们证明了无蛋白细胞分泌到培养基中的内源性蛋白在它们的增殖中通常起着负面作用。加入蛋白激酶C抑制剂的无蛋白培养细胞的增殖增强，虽然血清依赖性的增殖在相同的浓度被抑制。根据这些结果，刺激细胞增殖的外部信号在无蛋白质培养中不起作用，尽管信号包括自分泌生长因子和血清。另一方面，钙调素抑制剂抑制无蛋白细胞的增殖特异性。钙调素的免疫印迹显示，无蛋白质的细胞中的钙调素的核含量远高于血清依赖性克隆。最后，我们的自主增殖假说得到了证实。

We hypothesized that autonomic proliferation of tumor cells is internally programmed a priori, autocrine growth hypothesis may not be suitable to the autonomy of tumor cells in vitro. According to this hypothesis, we demonstrated that endogenous proteins secreted into the medium by protein-free cells play a negative role in the proliferation of them in general. Addition of protein kinase C inhibitor to the protein-free culture enhanced proliferation of cells, although serum-dependent proliferation were inhibited at the same concentration. From these results, external signals which stimulate cell proliferation do not play a role in the protein-free culture, although the signals included autocrine growth factors and serum. On the other hand, inhibitors against calmodulin suppressed the proliferation of protein-free cells specifically. Immunoblotting for calmodulin revealed that nuclear content of calmodulin in protein-free cells were much higher than that of serum-dependent clones. Finally, our autonomic hypothesis of proliferation has been proved.