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Trefoil proteins, TFF1, TFF2 and TFF3 are small molecular mass proteins that are secreted by mucus secreting epithelia. They share a three-looped structure, trefoil domain which contains six conserved cysteine residues that form three intramolecular disulphide bonds. TFF1 and TFF3 contain a seventh conserved uncoupled cysteine residue. In gastrointestinal mucosa, trefoil proteins are involved in stabilisation of the mucus layer, restitution of damaged mucosa and stimulation of epithelial cell motility. Increased expression of trefoil proteins has been reported in several human epithelial tumours and it has been proposed that trefoil proteins predispose to tumour cell migration, invasion and metastasis. Expression of trefoil genes is regulated by oestrogen in human breast cancer cell lines and strong association between expression of oestrogen receptor and expression of TFF1 and TFF3 mRNAs has been demonstrated in breast tumours. The role of trefoil proteins in breast cancer has not been fully understood. The purpose of this study is to investigate the molecular forms of TFF1 and TFF3 in breast cancer cells and to evaluate the expression of TFF1 and TFF3 in primary and metastatic breast tumours. The molecular forms of TFF1 and TFF3 proteins were examined in protein lysates and conditioned medium prepared from MCF-7, EFM-19 and EFF-3 breast cancer cell lines by western transfer analysis under non-reducing conditions and the different molecular forms were immunoprecipitated with anti-TFF1 and anti-TFF3 antibodies. Two distinct molecular forms of TFF1 and TFF3 were detected in breast cancer cell lines. They have approximate molecular masses of 66 kDa and 14.5 kDa for TFF1 and 66 kDa and 20 kDa for TFF3. The 66 kDa forms represent heterdimers that constitute one molecule of TFF1 or one molecule v of TFF3 bound to another protein of approximately 60 kDa through an intermolecular disulphide bond. The expression of TFF1 and TFF3 proteins was measured in 296 primary breast tumours and 76 metastatic deposits of breast tumours from patients who presented in the Newcastle Upon Tyne hospitals between 2002 and 2003 by immunohistochemistry. The association of TFF1 and TFF3 expression with various clinico-pathological features and with expression of oestrogen receptor, progesterone receptor, CD31, CD34, E-cadherin, Bcl-2 and Bax proteins was tested statistically with SPSS software (p |
