Molecular mechanisms involved in TFF3 peptide-mediated modulation of the E-cadherin/catenin cell adhesion complex.

TFF3 is a member of the TFF-domain peptide family which is constitutively expressed in mucous epithelial tissues where it acts as a motogenic factor and plays an important role during epithelial restitution after wounding and during inflammation. In contrast to these beneficial functions, TFFs were also reported to be involved in cell scattering and tumor invasion. These changes in epithelial cell morphology and motility are associated with a modulation of cell contacts. In this respect, we here investigated the E-cadherin/catenin cell adhesion complex in FLAG-hTFF3-transfected HT29/B6 and MDCK cells. In hTFF3-transfected cells the amount of E-cadherin is reduced with a concomitant reduction of alpha- and beta-catenin levels. On one hand, E-cadherin expression is lowered at the transcriptional level as shown by multiplex RT-PCR analysis. This decrease does not depend on differences in the promoter methylation status as shown by methylation-specific PCR. On the other hand, pulse-chase experiments showed a reduction in the E-cadherin half-life in hTFF3-transfected cells reflecting increased E-cadherin degradation. In summary, hTFF3 induces transcriptional and posttranslational processes resulting in a modulation of E-cadherin-mediated cell-cell contacts that may play an important role in the paradoxical benefical and pathogenic function of TFF peptides.

Generation of monoclonal antibodies against human regulatory T cells.

Natural CD4(+)CD25(+)Foxp3(+) regulatory T cells (Tregs) control the activation of the immune system and therefore have become a major area of research in immunology. The generation of monoclonal antibodies against human Tregs offers the possibility to discover novel Treg-specific or Treg-associated surface markers and to identify targets for a therapeutic modulation of Tregs. Here we present a methodology optimized to efficiently induce and select mAb against human Tregs by repeated immunization of mice with Tregs from a single donor and a differential two-step flow cytometry-based hybridoma screening procedure.

Her-2/neu and EGFR tyrosine kinase activation predict the efficacy of trastuzumab-based therapy in patients with metastatic breast cancer.

Her-2/neu overexpression in human breast cancer leads to an aggressive biological behavior and poor prognosis. Although the anti-Her-2/neu antibody trastuzumab (Herceptin(R)) has become a valuable therapeutic option for patients with Her-2/neu-overexpressing breast cancer, many patients do not benefit from this therapy. To evaluate the effect of receptor activation on tumor response, we have investigated the phosphorylation status of Her-2/neu and EGFR in 46 Her-2/neu-overexpressing tumor samples from trastuzumab-treated metastatic breast cancer patients by immunohistochemistry. Activated (p)tyr-1248 Her-2/neu was detected in 9 of 46 breast cancers (20%), and activated (p)tyr-845 and (p)tyr-1173 EGFR were both present in 6 tumors (13%) while EGFR was present in 16 cases (35%). ptyr-1248 Her-2/neu showed a trend to correlate with increased response to trastuzumab (p = 0.063), while ptyr-845, ptyr-1173 EGFR and EGFR did not. The presence of ptyr-1248 Her-2/neu and ptyr-845 or ptyr-1173 EGFR, however, was a strong predictor of both response to trastuzumab-based treatment (OR = 8.0, p = 0.021 and OR = 8.0, p = 0.021) and clinical benefit (OR = 5.47, p = 0.041 and OR = 6.22, p = 0.028 multivariate logistic regression analysis). Furthermore, ptyr-845 EGFR and ptyr-1248 Her-2/neu were both independent predictors of progression-free survival (RR = 0.21, p = 0.01 and RR = 0.45, p = 0.026, multivariate analysis). Patients with ptyr-845 EGFR positive tumors also tended toward increased overall survival (RR = 0.17, p = 0.082). Taken together, we have demonstrated that the determination of activated EGFR improves the utility of ptyr-1248 Her-2/neu staining in predicting the clinical outcome of patients undergoing trastuzumab treatment. We hypothesize that the activation state of both Her-2/neu and EGFR are key determinants for trastuzumab efficacy.