From the mechanistic perspective, it is interest ing to indicate that the TNF induced activation process of WT Ras took hours to complete, suggest ing www.selleckchem.com/products/Bortezomib.html that TNF induces the release of RTK ligands by the cells, which then activate the RTK Ras pathway and lead to increased transcription and protein expression of CXCL8. The involvement of RTK activation in this process is supported by published stud ies showing that TNF induces the transactivation of ErbB2 in other cell systems. Thus, in our sys tem, it is possible that ErbB2 stimulation may be in volved in the activation of WT Ras by TNF induced signals. EGF may be one of the ligands that activate the ErbB2 pathway, as suggested by our finding that EGF induced CXCL8 expression in ErbB2 expressing cells.

It is possible that the release of EGF and many other RTK ligands is induced as a consequence of TNF activation, leading to RTK activation and then to cooperation in the release of CXCL8 by the tumor cells. Obviously, a comprehen sive search based on protein arrays and neutralization assays would be required in order to identify the pro teins that mediate the TNF Inhibitors,Modulators,Libraries induced WT Ras activation observed in our system and such work would constitute an additional, full scale research project. Nevertheless, the actual evidence for such TNF activity significantly contributes to our understanding of the interactions be tween oncogenic events and microenvironmental pro cesses in breast cancer. Furthermore, in the malignant cells the hyper activated RasG12V can act alone to promote the Inhibitors,Modulators,Libraries release of the an giogenic chemokines CXCL8 and CCL2.

In contrast, in non transformed cells, the induction of CXCL8 and CCL2 requires synergism between at least two onco Inhibitors,Modulators,Libraries genic modifications, RasG12V and the down regulation of p53. The latter pattern, evident in the non transformed cells, is congruent with the regulatory patterns ob served for other tumor promoting characteristics in non transformed Inhibitors,Modulators,Libraries cells. In contrast, the transformed tumor cells already carried inherent alterations in Inhibitors,Modulators,Libraries their genetic signaling setup. Thus, the silencing of p53 may have been replaced by modified activities of other protein s in the tumor cells that exhibited a fully established malignancy phenotype. To identify candidate protein s whose alter ation may cooperate with RasG12V in depth analyses of the genetic signaling setup of the tumor cells would need to be carried out.

That work would be appropriate for future studies, but is beyond the scope of the present investigation. Our studies analyzing chemokine control by RasG12V p53 down regulation have revealed similarities but also dif ferences in the regulatory mechanisms determining the expression of CXCL8 and CCL2. As indicated above, RasG12V http://www.selleckchem.com/products/Gemcitabine-Hydrochloride(Gemzar).html alone induced the release of CXCL8 and of CCL2.