Tags

Type your tag names separated by a space and hit enter

Heregulin-beta is especially potent in activating phosphatidylinositol 3-kinase in nontransformed human mammary epithelial cells.
J Cell Physiol. 2000 Jun; 183(3):301-13.JC

Abstract

The neu differentiation factors/heregulins (HRGs) comprise a family of polypeptide growth factors that activate p185(erbB-2) through direct binding to either erbB-3 or erbB-4 receptor tyrosine kinases. We have previously shown that HRG-beta is mitogenic for various human mammary epithelial cell lines that coexpress c-erbB-2 and c-erbB-3. Phosphatidylinositol 3-kinase (PI3K) is activated by p185(erbB-2) /erbB-3 heterodimers in cells stimulated by HRG, and PI3K is constitutively activated by p185(erbB-2) /erbB-3 in breast carcinoma cells that overexpress c-erbB-2. To better understand the relative abilities of HRGs, epidermal growth factor (EGF), or insulin to activate PI3K under normal physiological conditions, we compared the levels of recruitment of the 85-kDa regulatory subunit of PI3K when activated by the type I (erbB) or type II [insulin-like growth factor (IGF)] receptor tyrosine kinases in two different nontransformed human mammary epithelial cell lines. The nontransformed H16N-2 cells isolated from normal tissue express EGFR, p185(erbB-2), and erbB-3, and are highly responsive to the mitogenic effects of HRG-beta as well as to the combination of EGF and insulin in serum-free culture. We measured the stoichiometry of p85 recruited by tyrosine-phosphorylated proteins induced in H16N-2 cells by either the alpha or the beta isoform of HRG. HRG-beta was greater than 10-fold more potent in inducing p85 recruitment than was the less biologically active HRG-alpha isoform. HRG-beta was also a more potent inducer of p85 recruited by tyrosine-phosphorylated proteins than was either EGF, insulin, or EGF and insulin combined. Furthermore, erbB-3 principally mediated the direct recruitment of p85 in cells stimulated by HRG or EGF, indicating that, in addition to the high-level activation of PI3K by p185(erbB-2) / erbB-3, EGFR/erbB-3 heterodimer interaction is essential for the weak but significant level of PI3K activated by EGF in cells that express normal EGFR levels. Studies using the PI3K inhibitor wortmannin also indicated that PI3K activation was required for the proliferation of H16N-2 cells induced by either HRG-beta or EGF and insulin in serum-free culture. Finally, HRG-beta was also an especially potent inducer of PI3K in the nontransformed MCF-10A cells, which were derived spontaneously from normal reduction mammoplasty tissue. These data show, for the first time, a side-by-side quantitative comparison of the relative degree of PI3K activated by different growth factors in nontransformed growth factor-dependent cells under precisely defined conditions in culture.

Authors+Show Affiliations

School of Biological Sciences, Washington State University, Pullman, Washington 99164-4236, USA. tram@mail.wsu.eduNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, U.S. Gov't, Non-P.H.S.
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

10797304

Citation

Ram, T G., et al. "Heregulin-beta Is Especially Potent in Activating Phosphatidylinositol 3-kinase in Nontransformed Human Mammary Epithelial Cells." Journal of Cellular Physiology, vol. 183, no. 3, 2000, pp. 301-13.
Ram TG, Hosick HL, Ethier SP. Heregulin-beta is especially potent in activating phosphatidylinositol 3-kinase in nontransformed human mammary epithelial cells. J Cell Physiol. 2000;183(3):301-13.
Ram, T. G., Hosick, H. L., & Ethier, S. P. (2000). Heregulin-beta is especially potent in activating phosphatidylinositol 3-kinase in nontransformed human mammary epithelial cells. Journal of Cellular Physiology, 183(3), 301-13.
Ram TG, Hosick HL, Ethier SP. Heregulin-beta Is Especially Potent in Activating Phosphatidylinositol 3-kinase in Nontransformed Human Mammary Epithelial Cells. J Cell Physiol. 2000;183(3):301-13. PubMed PMID: 10797304.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Heregulin-beta is especially potent in activating phosphatidylinositol 3-kinase in nontransformed human mammary epithelial cells. AU - Ram,T G, AU - Hosick,H L, AU - Ethier,S P, PY - 2000/5/8/pubmed PY - 2000/6/8/medline PY - 2000/5/8/entrez SP - 301 EP - 13 JF - Journal of cellular physiology JO - J. Cell. Physiol. VL - 183 IS - 3 N2 - The neu differentiation factors/heregulins (HRGs) comprise a family of polypeptide growth factors that activate p185(erbB-2) through direct binding to either erbB-3 or erbB-4 receptor tyrosine kinases. We have previously shown that HRG-beta is mitogenic for various human mammary epithelial cell lines that coexpress c-erbB-2 and c-erbB-3. Phosphatidylinositol 3-kinase (PI3K) is activated by p185(erbB-2) /erbB-3 heterodimers in cells stimulated by HRG, and PI3K is constitutively activated by p185(erbB-2) /erbB-3 in breast carcinoma cells that overexpress c-erbB-2. To better understand the relative abilities of HRGs, epidermal growth factor (EGF), or insulin to activate PI3K under normal physiological conditions, we compared the levels of recruitment of the 85-kDa regulatory subunit of PI3K when activated by the type I (erbB) or type II [insulin-like growth factor (IGF)] receptor tyrosine kinases in two different nontransformed human mammary epithelial cell lines. The nontransformed H16N-2 cells isolated from normal tissue express EGFR, p185(erbB-2), and erbB-3, and are highly responsive to the mitogenic effects of HRG-beta as well as to the combination of EGF and insulin in serum-free culture. We measured the stoichiometry of p85 recruited by tyrosine-phosphorylated proteins induced in H16N-2 cells by either the alpha or the beta isoform of HRG. HRG-beta was greater than 10-fold more potent in inducing p85 recruitment than was the less biologically active HRG-alpha isoform. HRG-beta was also a more potent inducer of p85 recruited by tyrosine-phosphorylated proteins than was either EGF, insulin, or EGF and insulin combined. Furthermore, erbB-3 principally mediated the direct recruitment of p85 in cells stimulated by HRG or EGF, indicating that, in addition to the high-level activation of PI3K by p185(erbB-2) / erbB-3, EGFR/erbB-3 heterodimer interaction is essential for the weak but significant level of PI3K activated by EGF in cells that express normal EGFR levels. Studies using the PI3K inhibitor wortmannin also indicated that PI3K activation was required for the proliferation of H16N-2 cells induced by either HRG-beta or EGF and insulin in serum-free culture. Finally, HRG-beta was also an especially potent inducer of PI3K in the nontransformed MCF-10A cells, which were derived spontaneously from normal reduction mammoplasty tissue. These data show, for the first time, a side-by-side quantitative comparison of the relative degree of PI3K activated by different growth factors in nontransformed growth factor-dependent cells under precisely defined conditions in culture. SN - 0021-9541 UR - https://www.unboundmedicine.com/medline/citation/10797304/Heregulin_beta_is_especially_potent_in_activating_phosphatidylinositol_3_kinase_in_nontransformed_human_mammary_epithelial_cells_ L2 - https://doi.org/10.1002/(SICI)1097-4652(200006)183:3<301::AID-JCP2>3.0.CO;2-W DB - PRIME DP - Unbound Medicine ER -