Ionising radiation is a potent human carcinogen. Epidemiological studies have shown that adolescent and young women are at increased risk of developing breast cancer following exposure to ionising radiation compared with older women, and that risk is dose-dependent. Although it is well understood which individuals are at risk of radiation-induced breast carcinogenesis, the molecular genetic mechanisms that underlie cell transformation are less clear. To identify genetic alterations potentially responsible for driving radiogenic breast transformation, we exposed the human breast epithelial cell line MCF-10A to fractionated doses of X-rays and examined the copy number and cytogenetic alterations. We identified numerous alterations of c-MYC that included high-level focal amplification associated with increased protein expression. c-MYC amplification was also observed in primary human mammary epithelial cells following exposure to radiation. We also demonstrate that the frequency and magnitude of c-MYC amplification and c-MYC protein expression is significantly higher in breast cancer with antecedent radiation exposure compared with breast cancer without a radiation aetiology. Our data also demonstrate extensive intratumor heterogeneity with respect to c-MYC copy number in radiogenic breast cancer, suggesting continuous evolution at this locus during disease development and progression. Taken together, these data identify c-MYC as a radiosensitive locus, implicating this oncogenic transcription factor in the aetiology of radiogenic breast cancer.

We have demonstrated that the peptides JB-1 and JB-23 do not inhibit the binding of IGF-1 to the type I IGF receptor and IGFBP. The peptides do, however, inhibit IGF-1 induced phosphorylation of the type I IGF receptor. Clearly this is not due to an inhibitory effect on the binding of IGF-1 to the receptor and the mechanism underlying the antagonist effect of the peptides on receptor phosphorylation remains unclear.

The present review will include the mammalian trefoil factors, TFF1, TFF2 and TFF3. It will summarise the amino acid sequences from different species, their posttranslational modifications and their structures determined by X-ray analysis and nuclear magnetic resonance studies. Trefoil factors all have a well-defined, structurally conserved trefoil domain. The trefoil domain consists of 42 or 43 amino acid residues and contains 6 cysteine residues that form disulphide bonds in a 1-5, 2-4 and 3-6 configuration. By the establishment of an additional intra-molecular disulphide bond at the C-terminal end, TFF1 and TFF3 form homodimers or heterodimers. This dimer formation of TFF1 and TFF3 will be discussed, and the possible implications for biological activity will be reviewed. The physicochemical characteristics including protease stability of trefoil factors will be summarised. The biological implications of different molecular forms of trefoil factors and their interaction with mucins will be discussed together with other functional insights.

Novel therapies for the treatment of colitis are required. We therefore examined the potential value of the trefoil factor family 1 (TFF1) peptide and epidermal growth factor (EGF) alone and in combination. Effects of TFF1- Cys58 +/- EGF on an in vitro HT29 cell wounding model of restitution showed synergistic activity when used in combination. In addition, animals had colitis induced by adding 4% dextran sulphate sodium (DSS) to the drinking water for 7 days and they also received twice daily subcutaneous injections of test peptides. Treatment with TFF1-Cys58 alone (100 microg/kg) reduced histological colitis score by 22%, but the TFF1-Ser58 variant was ineffective. In a second study, TFF1-Cys58 reduced histological colitis score by 15%, EGF (600 microg/kg) by 26%, and an additive response (42% reduction) was demonstrated when used together (P < 0.01 versus either peptide given alone). Similar results were found using tissue myeloperoxidase (MPO) activity as a marker of inflammation. Where clinical risk/benefit seems justified, these initial studies suggest that combination therapy of systemic EGF and TFF peptides may prove useful for treatment of colitis in patients with disease extending beyond the reach of topical (enema) therapy.

Aspirin has a role in the prevention of cardiovascular and cerebrovascular disease, Alzheimer's dementia and several cancers. Encouraging all 50 year olds to take low-dose aspirin doubles their chances of living a healthy life into their nineties. The widespread use of aspirin, however, is limited as many older subjects are currently unable to take aspirin because of gastrointestinal side-effects. This review explores why gastrointestinal events occur with aspirin use and how a net benefit from prophylactic aspirin might be achieved in older subjects. It is suggested that, by understanding the age-related changes in upper gastrointestinal physiology and the mechanisms by which aspirin leads to the risk reductions associated with its use, it may be possible to direct interventions to improve tolerability in older subjects. This would allow greater numbers of older subjects to gain the benefits associated with aspirin use.

The trefoil protein TFF1 is expressed principally in the superficial cells of the gastric mucosa. It is asmall protein and forms homo- and hetero-dimers via a disulphide bond through Cys58 which is located three aminoacids from the C terminus. TFF1 is co-expressed with the secreted mucin MUC5AC in superficial cells of the gastricmucosa suggesting that it could be involved in the packaging or function of gastric mucus. We have previouslyshown that TFF1 co-sediments with mucin glycoproteins on caesium chloride gradients. To extend this observationwe have now used gel filtration under physiological conditions, immunoprecipitation and Western transfer analysisto characterise the interaction of TFF1 with gastric mucin glycoproteins. We show that TFF1 co-elutes with MUC5ACbut not MUC6 on gel filtration and that immunoprecipitation and Western transfer analysis confirms that TFF1interacts with MUC5AC. We also demonstrate that the TFF1 dimer is the predominant molecular form bound to MUC5AC.Salt and chelators of divalent cations such as EDTA and EGTA disrupted the TFF1- MUC5AC interaction and increasedthe degradation of MUC5AC, whereas calcium increased the amount of TFF1 bound to MUC5AC. These data support thecontention that TFF1 is pivotal in the packaging and function of human gastric mucusa.

Trefoil proteins contain a conserved domain of distinctive structure. Three human trefoil proteins have been described to date of which the human spasmolytic polypeptide (hSP) and pNR-2/pS2 proteins have a similar pattern of expression in normal tissues. The genes encoding these two proteins were isolated from a human DNA library. Preliminary experiments suggested that some recombinants contained both genes. Southern hybridisation showed that all the recombinants were derived from a single stretch of DNA spanning 45 kb and suggested that the hSP gene was located downstream of the pNR-2/pS2 gene. Further experiments demonstrated that the two genes are transcribed in the same direction and that the distance between the 3′ end of the pNR-2/pS2 gene and the 5′ end of the hSP gene is 12.5 kb. The close linkage of these two genes is evidence that they have evolved by gene duplication and that their similar pattern of expression in normal tissues could result from the retention of common regulatory elements.