The Relationship between Human Epidermal Growth-like Factor Receptor Expression and Cellular Transformation in NIH3T3 Cells*
- From the Molecular Immunology Department, Bristol-Myers Squibb, Pharmaceutical Research Institute, Seattle Washington 98121 and
- § Amgen Inc., Thousand Oaks, California 91320
- ‡ To whom correspondence should be addressed. Tel.: 206-727-3559; Fax: 206-727-3603.
Abstract
A collection of cell lines expressing each human epidermal growth factor receptor (HER) family member alone or in all pairwise combinations in a clone of NIH3T3 cells (3T3-7d) devoid of detectable epidermal growth factor receptor family members has been generated. Transformation, as measured by growth in soft agar, occurred only in the presence of appropriate ligand and only in cells expressing two different HER family members. Transfection of oncogenic neu (Tneu), conferred ligand-independent transformation only in cells which co-expressed HER1, HER3, or HER4, but not when expressed alone or with HER2. Cell lines were also tested for their ability to form tumors in animals. None of the cell lines expressing single HER family members was able to form tumors in animals with the exception of HER1, which was weakly tumorigenic. Although unable to form tumors when expressed alone, HER2 was tumorigenic when expressed with HER1 or HER3, but not HER4. Of all complexes analyzed, cells expressing HER1 + HER2 were the most aggressive. The relationship between HER1 activation, intracellular calcium fluxes, and phospholipase Cγ1 activation is well established. We found that activation of HER1 was required for the induction of a calcium flux and the phosphorylation of phospholipase Cγ1. These activities were independent of, and unaffected by, the co-expression of any other family member. Further, heregulin stimulation of all cell lines including those containing HER1 did not demonstrate any effect on intracellular calcium levels or phospholipase Cγ1 phosphorylation. This demonstrates that heregulin induced cellular transformation by activating HER3- and HER4-containing complexes does not require the activation of either phospholipase Cγ1 or the mobilization of intracellular calcium.
Footnotes
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↵* The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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↵1 The abbreviations used are:
- EGF
-
epidermal growth factor
- EGFR
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epidermal growth factor receptor
- HER
-
human epidermal growth factor-like receptor
- HRG
-
heregulin
- DMEM
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Dulbecco's modified Eagle's medium
- FBS
-
fetal bovine serum
- PLC
-
phospholipase C
- PDGF
-
platelet-derived growth factor.
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↵2 B. D. Cohen, P. A. Kiener, J. M. Green, L. Foy, H. P. Fell, and K. Zhang, manuscript in preparation.
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- Received May 25, 1996.
- Revision received September 12, 1996.
- © 1996 by The American Society for Biochemistry and Molecular Biology, Inc.
