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Neu differentiation factor activation of ErbB-3 and ErbB-4 is cell specific and displays a differential requirement
R R Beerli1, D Graus-Porta, K Woods-Cook
1Friedrich Miescher-Institut, Basel, Switzerland.
Abstract:
Neu differentiation factor (NDF)-induced signaling involves the activation of members of the ErbB family of receptor tyrosine kinases. Although ectopic expression of recombinant ErbB receptors has yielded valuable insight into their signaling properties, the biological function and in vivo interplay of these receptors are still poorly understood. We addressed this issue by studying NDF signaling in various human cell lines expressing moderate levels of all known ErbB receptors. NDF-induced phosphorylation of ErbB-2 and ErbB-3 was found in the breast epithelial cell line MCF10A, the breast tumor cell lines T47D and MCF7, and the ovarian tumor cell line OVCAR3. Despite similar expression levels, NDF-induced phosphorylation of ErbB-4 was cell specific and only detected in T47D and OVCAR3 cells. Blocking cell surface expression of ErbB-2 by intracellular expression of a single-chain antibody revealed that in these two cell lines, ErbB-2 significantly enhanced phosphorylation of ErbB-4. Efficient NDF-induced phosphorylation of ErbB-3 was strictly ErbB-2 dependent in the breast tumor cell lines T47D and MCF7, while it was largely ErbB-2 independent in MCF10A and OVCAR3 cells. Consequently, NDF-stimulated intracellular signaling and induction of a biological response displayed a cell-specific requirement for ErbB-2. Thus, while ErbB-2 cooperates with NDF receptors in the breast tumor cell lines, ErbB-2 independent mechanisms seem to prevail in other cellular contexts.
Insights
Neu differentiation factor (NDF) signaling involves ErbB receptors. NDF triggers ErbB-2 and ErbB-3 phosphorylation, but ErbB-4 activation is cell-specific and often ErbB-2 dependent, impacting downstream signaling.
Area of Science:
- Cellular signaling pathways
- Receptor tyrosine kinases
- Cancer biology
Background:
- Neu differentiation factor (NDF) activates ErbB receptor tyrosine kinases.
- The in vivo interplay and biological functions of ErbB receptors are not fully understood.
- Previous studies often used ectopic expression, limiting insight into endogenous receptor interactions.
Purpose of the Study:
- To investigate NDF signaling in human cell lines with endogenous ErbB receptor expression.
- To elucidate the role of ErbB-2 in NDF-induced signaling and ErbB receptor interplay.
- To determine cell-specific differences in NDF signaling pathways.
Main Methods:
- Studied NDF signaling in human cell lines (MCF10A, T47D, MCF7, OVCAR3) expressing ErbB receptors.
- Analyzed NDF-induced phosphorylation of ErbB-2, ErbB-3, and ErbB-4.
- Utilized intracellular single-chain antibodies to block ErbB-2 function and assess its impact on ErbB-4 phosphorylation.
- Assessed cell-specific NDF-stimulated intracellular signaling and biological responses.
Main Results:
- NDF induced ErbB-2 and ErbB-3 phosphorylation in all tested cell lines.
- NDF-induced ErbB-4 phosphorylation was cell-specific (T47D, OVCAR3) and enhanced by ErbB-2.
- ErbB-3 phosphorylation was ErbB-2 dependent in breast tumor cells (T47D, MCF7) but independent in others (MCF10A, OVCAR3).
- ErbB-2's requirement for NDF-stimulated signaling and biological response varied by cell type.
Conclusions:
- ErbB-2 plays a cooperative role with NDF receptors in breast tumor cell lines.
- ErbB-2 independent mechanisms are significant in NDF signaling in other cellular contexts.
- Cell-specific interactions of ErbB receptors dictate NDF-induced signaling outcomes.