Bacus S S, Yarden Y, Oren M, Chin D M, Lyass L, Zelnick C R, Kazarov A, Toyofuku W, Gray-Bablin J, Beerli R R, Hynes N E, Nikiforov M, Haffner R, Gudkov A, Keyomarsi K
Advanced Cellular Diagnostics, Inc., Elmhurst, IL 60126, USA.
Oncogene. 1996 Jun 20;12(12):2535-47.
Previously we reported that neu differentiation factor (NDF)/heregulin (HRG) elevates tyrosine phosphorylation of its receptors erbB-3, erbB-4, and erbB-2 (through heterodimer formation). We also showed that both NDF/HRG and antibodies to erbB-2 can arrest growth and induce differentiation in breast cancer cells. In this study, we report on the mechanism of NDF/HRG-induced cellular effects. We show that NDF/HRG and antibodies to erbB-2 receptors up-regulate expression of p53 by stabilizing the protein. This is accompanied by up-regulation of the p53 inducible gene, p21CIP1/WAF1, in a variety of cell lines: MCF7 and their derivatives (MCF7/HER2, MN1 and MCF-7-puro), ZR75T and LnCap cells. The induction of p21 is further enhanced when cells are treated with both NDF/HRG and DNA-damaging chemotherapeutic agents (i.e. doxorubicin). The NDF/HRG mediated induction of p21 is dependent on wildtype p53, as it fails to occur in cells expressing dominant negative p53 (MDD2). Furthermore, p21 induction is capable of inactivating cdk2 complexes as measured by Histone H1 phosphorylation assays. Finally, we show that in primary cultures of breast and other cancers, p21 is significantly induced in response to NDF/HRG treatment. Collectively, these observations suggest that the mechanism of breast cancer cell growth inhibition and differentiation via erbB receptors activation is through a p53-mediated pathway.
此前我们报道过，神经分化因子（NDF）/ 这里调节素（HRG）可提高其受体erbB - 3、erbB - 4和erbB - 2的酪氨酸磷酸化水平（通过异二聚体形成）。我们还表明，NDF/HRG和erbB - 2抗体均可抑制乳腺癌细胞生长并诱导其分化。在本研究中，我们报告了NDF/HRG诱导细胞效应的机制。我们发现NDF/HRG和erbB - 2受体抗体通过稳定p53蛋白上调其表达。这伴随着多种细胞系中p53诱导基因p21CIP1/WAF1的上调，这些细胞系包括MCF7及其衍生物（MCF7/HER2、MN1和MCF - 7 - puro）、ZR75T和LnCap细胞。当细胞同时用NDF/HRG和DNA损伤性化疗药物（如阿霉素）处理时，p21的诱导进一步增强。NDF/HRG介导的p21诱导依赖于野生型p53，因为在表达显性负性p53（MDD2）的细胞中未发生这种诱导。此外，通过组蛋白H1磷酸化测定可知，p21诱导能够使cdk2复合物失活。最后，我们表明在乳腺癌和其他癌症的原代培养物中，NDF/HRG处理可显著诱导p21。总的来说，这些观察结果表明，通过erbB受体激活抑制乳腺癌细胞生长和诱导分化的机制是通过p53介导的途径。
