No abstract

Trefoil factor (TFF)1 is synthesized and secreted by the normal stomach mucosa and by the gastrointestinal cells of injured tissues. The link between mouse TFF1 inactivation and the fully penetrant antropyloric tumor phenotype prompted the classification of TFF1 as a gastric tumor suppressor gene. Accordingly, altered expression, deletion, and/or mutations of the TFF1 gene are frequently observed in human gastric carcinomas. The present study was undertaken to address the nature of the cellular and molecular mechanisms targeted by TFF1 signalling. TFF1 effects were investigated in IEC18, HCT116, and AGS gastrointestinal cells treated with recombinant human TFF1, and in stably transfected HCT116 cells synthesizing constitutive or doxycycline-induced human TFF1. We observed that TFF1 triggers two types of cellular responses. On one hand, TFF1 lowers cell proliferation by delaying G1-S cell phase transition. This results from a TFF1-mediated increase in the levels of cyclin-dependent kinase inhibitors of both the INK4 and CIP subfamilies, leading to lower E2F transcriptional activity. On the other hand, TFF1 protects cells from chemical-, anchorage-free–, or Bad-induced apoptosis. In this process, TFF1 signalling targets the active form of caspase-9. Together, these results provide the first evidence of a dual antiproliferative and antiapoptotic role for TFF1. Similar paradoxical functions have been reported for tumor suppressor genes involved in cell differentiation, a function consistent with TFF1.

Several phosphinic pseudo-tripeptides of general formula R-XaaPsi(PO(2)-CH(2))Xaa'-Yaa'-NH(2) were synthesized and evaluated for their in vitro activities to inhibit stromelysin-3, gelatinases A and B, membrane type-1 matrix metalloproteinase, collagenases 1 and 2, and matrilysin. With the exception of collagenase-1 and matrilysin, phosphinic pseudo-tripeptides behave as highly potent inhibitors of matrix metalloproteinases, provided they contain in P(1)' position an unusual long aryl-alkyl substituent. Study of structure-activity relationships regarding the influence of the R and Xaa' substituents in this series may contribute to the design of inhibitors able to block only a few members of the matrix metalloproteinase family.