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Aims: The present study attempts to shed light on the role and the relative position of the Na+/H+ exchanger isoform 1 (NHE1) and the extracellular signal-regulated kinase (ERK) in HEp-2 cell signaling pathways concerning a diverse range of cellular functions such as regulation of intracellular pH (pHi), DNA synthesis, production of reactive oxygen species (ROS) and apoptosis. Methods: Pharmacological inhibition with cariporide (highly specific inhibitor of NHE1) and PD98059 (specific inhibitor of the upstream activator of ERK) was implemented. Fluorescence spectrometry, atomic absorption spectrometry and ELISA methods were used in order to obtain the results. Results: NHE1 and ERK take part in all of the aforementioned cellular functions, as their inhibition had an effect on all of them. Additionally, inhibition of NHE1 resulted in ERK inhibition as well. Moreover, continuous inhibition of NHE1 or ERK for up to 24h led HEp-2 cells to apoptosis, as assessed through caspase-3 activation, DNA fragmentation and annexin-V binding levels. Conclusion: Our data shows a time course of events in relation to NHE1 and ERK and suggests the existence of a positive feedback loop between NHE1 and ERK which could pose a barrier against apoptosis. Copyright © 2006 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Background: It has been reported that the laminin derivative synthetic peptide YIGSR can bind to a metastasis-associated laminin receptor and inhibit experimental metastasis. Several antiidiotypic antibody (anti-Id) vaccines have been used in clinical trials with promising results. We used an anti-Id vaccine based on peptide YIGSR for the inhibition of spontaneous metastasis in Lewis Lung carcinoma-bearing mice., Materials and Methods: High titer anti-YIGSR serum from immunized rabbits was used to immunize sixteen Lewis Lung Carcinoma (LLC)-bearing mice. Another group of sixteen mice (controls) inoculated with LLC was immunized with control rabbit serum. After 24 days of tumor growth, the volume of the tumor was estimated, a blood sample was collected and the lungs were examined macroscopically and microscopically for metastasis. The presence of anti-Id antibodies was detected by Western blotting, ELISA and inhibition of cell attachment assays., Results: Tumor growth was limited and metastasis was inhibited in the mice that received the anti-Id YIGSR vaccine as compared to controls. Both groups of mice developed anti-rabbit antibodies as indicated by Western blotting. However only the serum of mice immunized with high titer anti-YIGSR rabbit serum (anti-Id YIGSR vaccine) could inhibit the binding of the anti-YIGSR rabbit serum to the peptide YIGSR in ELISA assays. In addition the serum of mice that received the anti-Id YIGSR vaccine but not the controls inhibited cell attachment to the peptide on solid face assays., Conclusion: An anti-Id antimetastatic vaccine may be developed based on YIGSR.