Copyright Marchini et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Signal transduction-related profile of A17.
A17 cells exhibit a clearly different pattern of expression and activation (phosphorylation) of key signal transduction molecules compared to syngeneic epithelial cell lines (BB1 and sB7) (a). ERK1/2 or Akt proved to be constitutively expressed but not phosphorylated in A17 cells. In contrast, P-ERK1/2 and P-Akt were found in both BB1 and sB7 cells, where they are presumably recruited downstream of the HER-2/neu signaling pathway. Furthermore, whereas both epithelial and A17 cells proved to express Focal Adhesion Kinase (FAK), we found an increased phosphorylation of paxillin and p130 Cas in A17 cells, which is in line with the constitutively motile phenotype of these mesenchymal cells. p-38 was expressed and activated in both epithelial and A17 cells. Microarray analysis restricted to 96 signal transduction-related genes show the A17 cell profile to be more related to that of MSCs than that of syngenic epithelial cells (BB1). However, the A17 tumor profile was shown to be more correlated to that of epithelial tumors than that of epithelial or mesenchymal cells (b). The differential expression of COX-2 in A17 compared to epithelial cells was confirmed at the transcriptional level through quantitative real-time PCR (Figure 1c). Western Blot analysis confirmed the differential expression of COX-2, but not of COX-1, in A17 cells and tumors comapared to BB1 cells and tumors (figure 1d). Differential expression of COX-2 protein between A17 and BB1 was also confirmed by immunocytochemistry on cell cultures (Figure 1d, right-up panles) and immunohistochemistry on tumor slices (figure 1e).