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EGF-R dependent regulation of keratinocyte survival
Abstract:
Tissue organization and maintenance within multicellular organisms is in part dependent on the ability of cells to undergo programmed cell death or apoptosis. Conversely, disruption of cell death pathways often is associated with tumor development. At present, the molecular control of apoptosis in epithelial cells is poorly understood. Here we describe evidence linking epidermal growth factor-receptor (EGF-R) activation to survival of normal human keratinocytes in culture. Inhibition of EGF-R activation by an anti-EGF-R antagonistic monoclonal antibody (mAb 425), followed by detachment of keratinocytes from the substratum, induced extensive death with several features of apoptosis in keratinocyte cultures. Other, non-epithelial normal human cells including melanocytes and fibroblasts, did not show this effect. Similar to EGF-R blockade by mAb 425, inhibition of the EGF-R tyrosine kinase activity using tyrphostin AG1478 resulted in lack of attachment and extensive cell death upon passaging. Attachment to keratinocyte-derived ECM partially resuced mAb 425-treated keratinocytes from cell death, indicating that adhesion-dependent and EGF-R-dependent signal transduction pathways serve partially overlapping but not redundant roles in supporting keratinocyte survival.
Insights
Epidermal growth factor-receptor (EGF-R) activation promotes survival in human keratinocytes. Blocking EGF-R signaling or cell attachment triggers apoptosis, highlighting their roles in skin cell maintenance.
Area of Science:
- Cell Biology
- Dermatology
- Molecular Biology
Background:
- Tissue organization relies on programmed cell death (apoptosis).
- Dysregulation of apoptosis is linked to tumor development.
- Molecular mechanisms governing apoptosis in epithelial cells, like keratinocytes, are not fully understood.
Purpose of the Study:
- To investigate the role of epidermal growth factor-receptor (EGF-R) in the survival of normal human keratinocytes.
- To elucidate the molecular control of apoptosis in epithelial cells.
Main Methods:
- Inhibition of EGF-R activation using an anti-EGF-R antagonistic monoclonal antibody (mAb 425).
- Inhibition of EGF-R tyrosine kinase activity using tyrphostin AG1478.
- Assessment of keratinocyte detachment, cell death, and apoptosis features.
- Evaluation of the effect of attachment to keratinocyte-derived extracellular matrix (ECM).
Main Results:
- Inhibition of EGF-R activation by mAb 425 induced keratinocyte detachment and apoptosis.
- Tyrphostin AG1478 also led to detachment and cell death.
- Non-epithelial cells (melanocytes, fibroblasts) did not exhibit similar responses.
- Attachment to keratinocyte-derived ECM partially protected cells from mAb 425-induced death.
Conclusions:
- EGF-R activation is crucial for the survival of normal human keratinocytes.
- Adhesion-dependent and EGF-R-dependent signaling pathways play overlapping, non-redundant roles in keratinocyte survival.
- Understanding these pathways is vital for comprehending epithelial cell homeostasis and potentially treating related disorders.