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Growth factor rescue of cytokine mediated trophoblast apoptosis
S Smith1, R Francis, L Guilbert
1Department of Obstetrics, Gynaecology and Midwifery, School of Human Development, City Hospital, University of Nottingham, Nottingham, UK.
Introduction:
Apoptosis can be induced in cytotrophoblasts and syncytiotrophoblast in culture by a combination of TNF-alpha and IFN-gamma (Yui et al., 1994a; Garcia-Lloret et al., 1996). This apoptotic action of TNF-alpha and IFN-gamma can be inhibited/'rescued' by EGF (Garcia-Lloret et al., 1996). Additional 'survival' factors have been sought which might protect cells against apoptosis induced by TNF-alpha/IFN-gamma. The survival factors investigated were bFGF, IGF-1, PDGF-AA, VEGF and PLGF. These cytokines were chosen specifically because in common with EGF, the receptors for these molecules are all direct protein tyrosine kinases.
Materials And Methods:
All the experiments were carried out using a standard cell culture protocol (Yui et al., 1994a, b; Garcia-Lloret et al., 1996). Apoptosis was induced using TNF-alpha/IFN-gamma, and rescue was attempted using the various cytokines. Apoptosis was identified using the TUNEL technique and quantified by counting 3000 cells in each experimental well.
Results:
As in previous studies EGF produced a complete inhibition of the apoptotic action of TNF-alpha/IFN-gamma. bFGF, IGF-1, and PDGF-AA produced a partial but significant inhibition of the apoptotic action of TNF-alpha/IFN-gamma. VEGF and PLGF in these experiments had no protective effects against TNF-alpha/IFN-gamma induced apoptosis.
Discussion:
Previous studies relating to EGF have been confirmed. bFGF, IGF-1, and PDGF have all been shown to provide partial protection against TNF-alpha/IFN-gamma induced apoptosis. VEGF and PLGF did not protect against apoptosis, and the mechanisms of action remain unclear.