The p130Cas Co 2 a is requires c Src and JNK activities to sustain mesenchymal traits To assess whether the p130Cas Co 2 a is is effective also in the human setting, we chose the human lung metastatic MDA MB 231 subpopulation LM2 4175 as they recapitulate A17 cell features with high levels of Co 2 e pression and a mesenchymal pheno type. Upon selleck chem Trichostatin A infection with lentiviral particles carrying human p130Cas shRNA, the marked downregulation of p130Cas was associated with a concomitant decrease in Co 2, Snail, Slug and Twist. Accordingly, p130Cas silenced cells reorganized in colo nies that lost their elongated protrusions, acquiring a more polygonal shape, as quantified by a marked decreased in length width ratio.

Re e pression of a mouse full length p130Cas GFP fused protein in LM2 4175 p130Cas silenced cells, re established Co 2 and mesenchymal markers e pression at the same level of control cells, and consistently p130Cas reconstituted cells reacquired elongated protrusions. Moreover, p130Cas silencing led to a strong reduction of c Src and JNK activities, similar to those observed in in vivo tumor grafts derived from p130Cas silenced A17 cells. Interestingly, cell treatment with specific inhibitors of c Src or JNK activities for 16 hrs, caused a switch to an epithelial morphology similar to that observed upon p130Cas downregulation. Consistent with the fact that Src and JNK controls Co 2 e pression, both inhibitors caused downregulation of Co 2, and a reduction in Snail, Slug and Twist e pression, without grossly affecting p130Cas levels.

In addition, cells treated with the c Src inhibitor SU6656 showed a decrease in JNK activity, while the JNK inhibitor SP600125 did not affect c Src phosphorylation, suggesting that Src activity is upstream to JNK activation. Moreover, in A17 cells, luciferase assays revealed that the reporter e pression driven by Co 2 promoter was decreased AV-951 by the use of Src inhibitor and practically abrogated with JNK inhibi tor. Overall these data show that the p130Cas Co 2 a is is effective both in the mouse and in the human setting. c Src and JNK kinases appear as sequential players in this a is and their pharmacological inhibition was sufficient to down regulate Co 2 and to induce an epithelial phenotype.

These results also suggest the potential clinical applica tion of targeting c Src through pharmacological inhibi tors in breast tumors e pressing high levels of p130Cas and Co 2, the same strategy already proposed in HER2 positive trastuzumab resistant tumors to over come trastuzumab kinase inhibitor Tofacitinib resistance. Finally, in order to evaluate whether the p130Cas Co 2 a is has clinical relevance in human breast cancer, pub licly available microarray data from the Netherlands Can cer Institute of 295 early stage breast cancer biopsies and from the Koo Foundation Sun Yat Sen Cancer Cen ter of 327 breast cancer tissues were analyzed.