Fiddes R J, Janes P W, Sanderson G M, Sivertsen S P, Sutherland R L, Daly R J
Co-operative Research Centre for Biopharmaceutical Research, Garvan Institute of Medical Research, St. Vincent's Hospital, Sydney, New South Wales, Australia.
Cell Growth Differ. 1995 Dec;6(12):1567-77.
The heregulins (HRGs) are a family of growth factors that bind direction to erbB3 and erbB4 and induce tyrosine phosphorylation of erbB2 via receptor heterodimerization. Since erbB2, erbB3, and erbB4 (erbB2-4) are often overexpressed in human breast cancer cells, we produced recombinant HRGs and a HRG-based ligand toxin to investigate the signaling events triggered by HRGs and the ability of these ligands to specifically target such cells. Recombinant HRG beta 2 stimulated the tyrosine phosphorylation of erbB2-4 in ZR-75-1 human breast cancer cells. This was accompanied by the tyrosine phosphorylation of Shc and the formation of complexes between Shc and the adapter protein Grb2. Complexes were also detected between Shc and erbB2-4. However, GRb2 was detected in erbB2 and erbB4 but not erbB3 immunoprecipitates. Thus, these receptors exhibit mechanistic differences in their coupling to Ras signaling, and HRG beta 2 administration triggers multiple inputs into the Ras signaling pathway, involving receptor-Grb2, receptor-Shc, and Shc-Grb2 complexes. HRG beta 2 addition also stimulated the association of erbB3 with phosphatidylinositol-3-kinase. In accordance with the activation of key mitogenic signaling pathways, HRG beta 2 stimulated the proliferation of MCF-7 and T-47D human breast cancer cells. Moreover, when tested for the ability to stimulate cell cycle re-entry of T-47D cells arrested under serum-free conditions, HRG beta 2 was more effective than insulin, previously the most potent mitogen identified using this system. Finally, a HRG beta 2 PE40 ligand toxin was constructed and found to exhibit cytotoxic activity against human breast cancer cells overexpressing erbB3 alone or in combination with erbB4 and/or erbB2.
这里生长因子（HRGs）是一类生长因子，可直接与erbB3和erbB4结合，并通过受体异源二聚化诱导erbB2的酪氨酸磷酸化。由于erbB2、erbB3和erbB4（erbB2 - 4）在人乳腺癌细胞中常常过表达，我们制备了重组HRGs和一种基于HRG的配体毒素，以研究HRGs触发的信号事件以及这些配体特异性靶向此类细胞的能力。重组HRGβ2刺激了ZR - 75 - 1人乳腺癌细胞中erbB2 - 4的酪氨酸磷酸化。这伴随着Shc的酪氨酸磷酸化以及Shc与衔接蛋白Grb2之间复合物的形成。在Shc与erbB2 - 4之间也检测到了复合物。然而，在erbB2和erbB4的免疫沉淀产物中检测到了Grb2，但在erbB3的免疫沉淀产物中未检测到。因此，这些受体在与Ras信号传导的偶联中表现出机制差异，并且给予HRGβ2会触发多个信号输入到Ras信号通路中，涉及受体 - Grb2、受体 - Shc和Shc - Grb2复合物。添加HRGβ2还刺激了erbB3与磷脂酰肌醇 - 3 - 激酶的结合。与关键促有丝分裂信号通路的激活一致，HRGβ2刺激了MCF - 7和T - 47D人乳腺癌细胞的增殖。此外，在测试刺激无血清条件下停滞的T - 47D细胞重新进入细胞周期的能力时，HRGβ2比胰岛素更有效，胰岛素是此前使用该系统鉴定出的最有效的促有丝分裂原。最后，构建了一种HRGβ2 - PE40配体毒素，发现其对单独过表达erbB3或与erbB4和/或erbB2联合过表达的人乳腺癌细胞具有细胞毒性活性。
