Of the 10 C terminal SH2 docking sites of human EGFR, most of inhibitor Dovitinib them with over lapping substrate specifity, Inhibitors,Modulators,Libraries 7 are conserved in Xmrk, sug gesting at least partial functional similarity. The melanoma cell line A375 reportedly expresses human EGFR and responds Inhibitors,Modulators,Libraries Inhibitors,Modulators,Libraries to addition of EGF. When induction of FOSL1, EGR1, OPN, IGFBP3, DUSP4 and TAAL6 was monitored after EGF stimulation between 15 minutes and 24 h, only the fast responding FOSL1 and EGR1 genes were found to be induced. Compared to HERmrk expressing melano cytes, FOSL1 upregulation was weaker in A375, while EGR1 induction was even stronger. As A375 cells express oncogenic BRAFV600E and already underwent the process of transformation, it is possible that ongoing endogenous aberrant signaling concealed EGFR stimulation in this cell line.

For this rea son, and to gain a better comparison to the untrans formed melan a Inhibitors,Modulators,Libraries HERmrk cells, we used melan a cells stably transfected with human EGFR and performed an experiment similar to the one per formed with A375 cells. Here, all investigated genes except Igfbp3 were upregulated in response to EGF. Apart from the downregulated Opn and Taal6 values at 24 h, the extent and time course of stimulation were com parable between HERmrk and HER stimulation. Among the genes identified, the protein encoded by FOSL1 constitutes an interesting candidate with a poten tial effect on melanoma biology. It is part of the AP 1 complex, which is a functional downstream target of the MAP kinase pathway that is commonly activated in mela noma.

Furthermore, c JUN, Inhibitors,Modulators,Libraries which might be a poten tial binding partner for FOSL1 in the AP 1 complex, is highly expressed in most melanoma and is required for tumor transformation. The human protein atlas database constitutes a platform which offers an extensive amount of protein expression data gained from a large variety of normal human tissues, cancer tissues and cell lines. Here, FOSL1 expression is low or non detectable in most tissues, and moderate in epidermal skin cells. Among melanoma tissues, two thirds express moderate or high levels of the protein, and both mela noma cell lines investigated also show high expression These data confirm our own observations, namely the increase of FOSL1 expression in transformed or activated pigment cells.

In our study, FOSL1 protein levels were not only upregulated in mouse melanocytes expressing HERmrk, but were also elevated in human melanoma cell lines compared to the human melanocyte cell line Hermes3a selleck chem and NHEM cells. Inhibition of MEK strongly reduced FOSL1 protein in HERmrk transgenic cells as well as in the human cell lines A375 and Mel Juso. This suggests that MAPK pathway activation by BRAFV600E and by NRASQ61K is important in maintaining FOSL1 expression. To investigate the effect of FOSL1 on melanoma growth, we downregulated FOSL1 in the mel anoma cell lines A375 and Mel Juso using siRNA.