Quantitative real-time PCR analysis and microarray-based RNA expression of HER2 in relation to outcome.

BACKGROUND: Our aim was to use quantitative real-time PCR (Q-PCR) and RNA expression profiles (RNA-EPs) to investigate HER2 status in relation to outcome. PATIENTS AND METHODS: Cut-off levels for Q-PCR and RNA-EP were established in relation to immunohistochemistry (IHC) validated by FISH in a test set of frozen tissue samples from 40 primary breast cancers. The HER2 status was subsequently studied in another validation set of 306 tumors, where Q-PCR and RNA-EP results were compared with previously carried out IHC that we had validated by chromogenic in situ hybridization (CISH). RESULTS: Q-PCR and RNA-EP offered similar sensitivity (90% versus 77%), specificity (93% versus 95%), and negative (99% versus 98%) and positive (63% versus 61%) predictive values for HER2 determinations. Analyses of relapse-free survival (RFS) and overall survival on the basis of 5 and 10 years of follow-up indicated equivalent hazard ratios for all three techniques. In contrast to IHC/CISH, both Q-PCR and RNA-EP analyses of HER2 also gave statistically significant results regarding RFS and breast cancer-corrected survival after 10 years of follow-up. CONCLUSION: The use of RNA-EP and Q-PCR to analyze HER2 in frozen and formalin-fixed breast cancer samples may be an alternate approach to IHC in combination with FISH/CISH.

Pro-inflammatory mediator leukotriene D4 induces transcriptional activity of potentially oncogenic genes.

The inflammatory mediator LTD4 (leukotriene D4) is present at high levels in many inflammatory conditions, and areas of chronic inflammation have an increased risk for subsequent cancer development. We demonstrate here that following LTD4 stimulation, beta-catenin is translocated to the nucleus, triggering the transcriptional activity of the TCF (T-cell factor)/LEF (lymphoid enhancer factor) family of transcription factors. These events are dependent on phosphoinositide-3 kinase activation and glycogen synthase kinase inhibition. Our data suggest that, similar to Wnt signalling, LTD4 increases free beta-catenin and targets it to the nucleus.

Leukotrienes induce cell-survival signaling in intestinal epithelial cells.

BACKGROUND & AIMS: Inflammatory bowel conditions, particularly ulcerative colitis, are associated with an increased incidence of neoplastic transformation. High levels of proinflammatory leukotrienes (LTs) and up-regulated expression of cyclooxygenase (COX)-2 are characteristic of inflammation. Moreover, COX-2 has been implicated in cell survival and early colon carcinogenesis. Other aspects of interest for intestinal cell viability are the levels of beta-catenin and the antiapoptotic protein Bcl-2. We investigated the possibility that LTs participate in the regulation of these survival factors. METHODS: We used the human intestinal epithelial cell line Int 407 and the rat intestinal epithelial cell line IEC-6. Immunoblotting was applied to ascertain protein expression and distribution, and enzyme immunoassay methodology was used to measure prostaglandin E(2) (PGE(2)) production. Apoptotic ability was assessed by trypan blue exclusion, Hoechst staining, DNA fragmentation, and a caspase-3 activity assay. RESULTS: LTD(4) and LTB(4), but not LTC(4), caused a time- and dose-dependent increase in expression and/or membrane accumulation of COX-2, beta-catenin, and Bcl-2, as well as PGE(2) production. Apoptosis assays showed that the effects of LTs on these transformation-associated proteins correlated well with the ability of these LTs to reduce programmed cell death. CONCLUSIONS: The results suggest that inflammatory conditions are associated with the expression and distribution of proteins that are characteristic of transformed cells; such conditions may involve a signaling mechanism comprising an altered rate of apoptosis.

Leukotriene D4-induced signalling events in human epithelial cells: G alpha i3 activation and translocation.

Our model of LTD4-induced signal transduction in epithelial cells is summarised in Figure 2. Extending what is already known about LTD4 signalling in epithelial cells, we identified the Gi3-protein as the crucial PTX sensitive G-protein and found that it is translocated to what might be a cytoskeletal fraction. This finding suggests a subtle response to LTD4, mediated via the bifurcation at the alpha/beta gamma junction. Although little is known about the role of epithelial cells in inflammation, it has been shown that such cells produce the potent chemoattractant LTB4 and the proinflammatory 5-HETE in response to intracellular accumulation of Ca2+ 24. The target protein(s) and the effect(s) of the translocation of the activated G alpha i3-proteins, as well as the possible role of the beta/gamma-subunits of Gi3, remain to be elucidated.

Leukotriene D4-induced activation and translocation of the G-protein alpha i3-subunit in human epithelial cells.

The present results show that stimulation of Intestine 407 epithelial cells with LTD4 (Leukotriene D4) triggers a rapid activation of the pertussis-toxin-sensitive Gi3-protein and a simultaneous translocation of its alpha-subunits to a crude cytoskeletal fraction. The activation of G alpha i3, which was measured as the GTP/ GDP exchange ratio, peaked about 15 s after the addition of LTD4. Western blot analyses of subcellular fractions showed that G alpha i3-subunits accumulated in the cytoskeletal fraction and decreased in the membrane fraction, and the decrease was most marked 15 s after the exposure to LTD4. None of the other pertussis-toxin-sensitive G-proteins (Gi3-Z and G alpha 0) were activated or translocated upon stimulation with LTD4. This agonist was also found to reduce the GTP/GDP exchange ratio of Gi-proteins without affecting the subcellular distribution of its alpha-subunits. These findings imply that the Gi3-protein is the pertussis-toxin-sensitive G-protein previously found to mediate several downstream LTD4-stimulated signalling events. Furthermore, the translocation of G alpha i3-subunits to the cytoskeleton and the simultaneous inhibition of G3-proteins indicate that the cytoskeleton might participate in the signalling process of human epithelial cells.