AbstractMigration Stimulating Factor (MSF) is an oncofoetal protein which is constitutively produced by both epithelial and stromal cells during foetal development, not expressed by the majority of their normal adult counterparts, but re-expressed during pathological processes such as cancer and wound healing. Scotland has the highest occurrence of oral cancers in the UK; the incidence is still increasing, but patient survival remains very poor. The expression of MSF in oral tumours has not been previously reported.
The aims of this study were:
• To determine the effects of MSF on the migration of oral tumour cell lines and normal stromal cells in culture (chapter 3),
• To ascertain the possible presence, diagnostic and prognostic value of MSF in oral squamous cell carcinoma (OSCC; chapter 4), and salivary gland tumours (SGT; chapter 5).
• To identify the putative MSF receptors in oral tumour cell lines (chapter 6).
For tissue culture studies, the effects of rhMSF (wild type and mutant proteins) were examined on human cell lines TYS, HSG, Endo 742 and FSF44. These cells were derived from OSCC, SGT, microvascular endothelial cells and skin fibroblasts, respectively. For ex-vivo studies, paraffin embedded archival specimens of OSCC and SGT were stained with specific MSF antibodies and the level of staining was assessed by consensus of 2-4 independent observers. The association between MSF expression and patient survival was determined by Kaplan-Meier and log-rank tests.
Results presented in this thesis indicate that TYS and HSG cells secrete bioactive MSF in culture. rhMSF stimulated the migration of these tumour cells. The use of mutant proteins demonstrated marked differences among the cells examined: Five bioactive motifs (4x IGD and 1x HEEGH) were required for MSF bioactivity on TYS and HSG cells, whereas only one of these motifs was required for Endo 742 and two for FSF44. MSF+aa and MSF-aa showed the same migration-stimulating activity, but differ in their interaction with the MSF-inhibitor Neutrophil Gelatinase-Asscciated Lipocalin (NGAL). NGAL was shown to bind to and inhibit MSF+aa, but not MSF-aa. The bioactivity of MSF+aa and MSF-aa was inhibited by Insulin-like Growth Factor Binding Protein-7 (IGFBP7), MSF-function-neutralising antibody and antibody to the integrin avß3. This integrin was identified in the cell membrane material bound to MSF, suggesting that avß3 is a receptor for MSF.
Analyses of MSF staining in tissue sections indicated that MSF is expressed by most OSCC and malignant SGT, being heterogeneously present in both carcinoma and stromal cells. In SGT, significantly higher levels of total MSF and MSF-aa were detected in malignant than in benign tumours. In OSCC, high MSF expression in the invasive tumour front (ITF) was significantly associated with poor patient survival. MSF-aa was more informative than total MSF.
This study suggests that MSF stimulates tumour cell migration in an autocrine and paracrine manner, modulated by the type of MSF isoform expressed and by the presence of NGAL and other possible inhibitors. This provides a rational platform for subsequent more extensive investigations of the possible diagnostic and prognostic significance of MSF expression in oral tumours.
|Date of Award||2012|
|Supervisor||Ana Schor (Supervisor), Ian Ellis (Supervisor) & Sarah Jones (Supervisor)|
- MSF (Migration Stimulating Factor)
- Salivary gland tumours